A control system to optimize response time of a plurality of engines of a machine is provided. The control system includes a controller configured to determine a first engine group and a second engine group based on data regarding response time characteristics of the plurality of engines, control the first engine group to increase output power of the machine when the output power of the machine is below a predetermined power output threshold, and control the second engine group to increase output power of the machine responsive to the output power of the machine reaching the predetermined power output threshold. A response time of the first engine group is faster than a response time of the second engine group when the output power of the machine is below the predetermined power output threshold.

Generally, in machines, such as marine vessels and land drilling power generating machines, power resource systems that include a plurality of power resources are employed. The plurality of power resources may be engines working together to provide power for the machine.
Power distribution strategies for such multi-power resources may be based on a predefined ratio divided between the power resources. In such power distribution strategies, when operating the machine preference may be given to a power resource with relatively higher power output over a power resource with a lower power output. However, a larger power resource may take relatively more time to adapt in response to a change in required power of the machine. As a result, response time of the machine to such change in required power may be relatively slow. Therefore, haphazard utilization of power resources, particularly a plurality of engines of a multi-power resource system, may lead to undesirably long response times.
U.S. Pat. No. 8,606,424, hereinafter referred to as the '424 patent, relates to a particle swarm optimization (PSO) method for microgrids that formulates a control problem as an optimization problem, and PSO is used to search the solution space for optimal parameter settings in each mode. According to the '424 patent, the procedure models optimal design of an LC filter, controller parameters and damping resistance in grid-connected mode, and optimizes the controller parameters and power sharing coefficients in an autonomous mode. Nonlinear time-domain-based and eigenvalue-based objective functions are used to minimize the error in the measured power, and also to enhance the damping characteristics, respectively. However, the system disclosed in the '424 patent may not adequately perform power distribution control strategies between different engine groups to optimize engine output power response time in response to a change in required engine output power.

Systems, apparatuses, and methods to control output power of groups of engines


A semiconductor device includes a 3-input NAND decoder having six MOS transistors arranged in a line. The MOS transistors of the decoder are formed in a planar silicon layer disposed on a substrate and each have a structure in which a drain, a gate, and a source are arranged vertically and the gate surrounds a silicon pillar. The planar silicon layer includes a first active region having a first conductivity type and a second active region having a second conductivity type. The first and second active regions are connected to each other via a silicon layer on a surface of the planar silicon layer.

1. Field of the Invention
The present invention relates to a semiconductor device.
2. Description of the Related Art
With the recent increase in the integration of semiconductor integrated circuits, semiconductor chips having as large a number of transistors as 1,000,000,000 (1 Giga (G)), have been developed for state-of-the-art micro-processing units (MPUs). As disclosed by Hirokazu YOSHIZAWA in "Shi mosu opi anpu kairo jitsumu sekkei no kiso (Fundamentals on CMOS OP amp circuit design for practical use)", CQ Publishing Co., Ltd., Aug. 1, 2007, p. 23, traditional transistors formed in a planar manner, called planar transistors, require complete isolation of an n-well region that forms a p-channel metal-oxide semiconductor (PMOS) and a p-type silicon substrate (or p-well region) that forms an n-channel metal-oxide semiconductor (NMOS) from each other. In addition, the n-well region and the p-type silicon substrate require body terminals for applying potentials thereto, which will contribute to a further increase in the area of the transistors.
To address the issues described above, a surrounding gate transistor (SGT) having a structure in which a source, a gate, and a drain are arranged in a direction perpendicular to a substrate and in which the gate surrounds an island-shaped semiconductor layer has been proposed, and a method for manufacturing an SGT and a complementary metal-oxide semiconductor (CMOS) inverter, a NAND circuit, or a static random access memory (SRAM) cell which employs SGTs are disclosed (see, for example, Japanese Patent No. 5130596, Japanese Patent No. 5031809, Japanese Patent No. 4756221, and International Publication No. WO2009/096465).
FIGS. 21, 22, and 23 illustrate a circuit diagram and layout diagrams of an inverter that employs SGTs.
FIG. 21 is a circuit diagram of the inverter. The symbol Qp denotes a p-channel MOS transistor (hereinafter referred to as a "PMOS transistor"), the symbol Qn denotes an n-channel MOS transistor (hereinafter referred to as an "NMOS transistor"), the symbol IN denotes an input signal, the symbol OUT denotes an output signal, the symbol Vcc denotes a power supply, and the symbol Vss denotes a reference power supply.
FIG. 22 illustrates a plan view of the layout of the inverter illustrated in FIG. 21, which is formed by SGTs. FIG. 23 illustrates a cross-sectional view taken along the cut-line A-A′ in the plan view of FIG. 22.
In FIGS. 22 and 23, planar silicon layers 2p and 2n are formed on top of an insulating film such as a buried oxide (BOX) film layer 1 disposed on a substrate. The planar silicon layers 2p and 2n are formed as a p+ diffusion layer and an n+ diffusion layer, respectively, through impurity implantation or the like. Reference numeral 3 denotes a silicide layer disposed on surfaces of the planar silicon layers (2p and 2n). The silicide layer 3 connects the planar silicon layers 2p and 2n to each other. Reference numeral 4n denotes an n-type silicon pillar, and reference numeral 4p denotes a p-type silicon pillar. Reference numeral 5 denotes a gate insulating film that surrounds the silicon pillars 4n and 4p. Reference numeral 6 denotes a gate electrode, and reference numeral 6a denotes a gate line. A p+ diffusion layer 7p and an n+ diffusion layer 7n are formed in top portions of the silicon pillars 4n and 4p, respectively, through impurity implantation or the like. Reference numeral 8 denotes a silicon nitride film for protecting the gate insulating film 5 and the like, and reference numerals 9p and 9n denote silicide layers for connection to the p+ diffusion layer 7p and the n+ diffusion layer 7n, respectively. Reference numerals 10p and 10n denote contacts that respectively connect the silicide layers 9p and 9n to metal lines 13a and 13b. Reference numeral 11 denotes a contact that connects the gate line 6a to a metal line 13c.
The silicon pillar 4n, the diffusion layer 2p, the diffusion layer 7p, the gate insulating film 5, and the gate electrode 6 constitute the PMOS transistor Qp. The silicon pillar 4p, the diffusion layer 2n, the diffusion layer 7n, the gate insulating film 5, and the gate electrode 6 constitute the NMOS transistor Qn. The diffusion layers 7p and 7n serve as sources, and the diffusion layers 2p and 2n serve as drains. The power supply Vcc is supplied to the metal line 13a, and the reference power supply Vss is supplied to the metal line 13b. The input signal IN is connected to the metal line 13c. The output signal OUT is output from the silicide layer 3, which connects the drain of the PMOS transistor Qp, or the diffusion layer 2p, to the drain of the NMOS transistor Qn, or the diffusion layer 2n.
In the inverter illustrated in FIGS. 21, 22, and 23, which employs SGTs, the PMOS transistor and the NMOS transistor are structurally isolated completely from each other. This configuration eliminates the need for isolation of wells, unlike planar transistors. In addition, the silicon pillars act as floating bodies. This configuration eliminates the need for any body terminals for supplying potentials to the wells unlike planar transistors. The layout (arrangement) of the inverter is thus compact.

This patent is subject to a terminal disclaimer.

UNISANTIS ELECTRONICS SINGAPORE PTE. LTD.


An automatic shutoff valve for shutting off the main water supply to a building in the case of detected water leak. A ball valve is provided with a mounting kit for rendering the valve automatic. The apparatus includes a housing adapted to fit over the valve body and secured directly to the pipes with adjustable clamps. The kit includes a two-section lever member pivotally mounted to the valve. The one-quarter turn movement of the lever member determines the opening and the closing of the valve. A spring-loaded cable and a system of pulleys control the lever member. A retaining member is pivotally mounted to the floor of the housing and a pair of arms extends outwardly therefrom with one arm of the retaining member engaging a slot in the upper end of the internal section of the lever member to retain the valve in the opened position. The retaining member has a second arm extending in the direction opposite to the first arm and is connected to a solenoid device which can be actuated to pivot the retaining member to disengage the slot of the lever from the latch of the retaining member allowing the extension spring to close the valve. A manual closing device is also provided to disengage the slot of the lever without the action of the solenoid device. Once the internal section of the lever is at the closed position, an indicator-switch monitors a signal confirming the closing of the valve.

1. Field of the Invention
The present invention relates to an automatic flood control valve apparatus and more particularly to an improved mechanism for closing a normally open ball valve in a water supply system.
2. Description of the Prior Art
There are many systems for automatically controlling a valve to interrupt the flow of different fluids and particularly the water supply in the event that flooding occurs due a leak somewhere in a water system. For instance, U.S. Pat. Nos. 5,966,076, Cantrell, Oct. 12, 1999; U.S. Pat. No. 5,694,970, Staranchuck, Dec. 9, 1997; U.S. Pat. No. 5,298,088, Gray, Jr. Mar. 29, 1994; U.S. Pat. No. 5,240,022, Franklin, Aug. 31, 1993; U.S. Pat. No. 5,193,780, Franklin, Mar. 16, 1993; U.S. Pat. No. 4,889,313 Sanchez, Dec. 26, 1989; U.S. Pat. No. 4,659,063 Veillette, Apr. 21, 1987; U.S. Pat. No. 4,324,268, Jacobson, Apr. 13, 1982. all show a normally opened valve provided in a fluid system as water, gas or air system. Sensors for detecting a leak are linked to an electrical circuit for operating a solenoid for moving a plunger which operates the valve to close it. The valve must be manually reset in order to reopen the valve.


An intracerebral current simulation method including a first step of providing head image data; a second step of forming a three-dimensional brain model including micro-polyhedron units; a third step of providing first information which includes conditions under which a coil is placed on a patient's head, an electric current is applied to the coil, and the patient's reaction to the magnetic stimulation is observed, the conditions including a position and orientation of the coil, an electric current applied to the coil, and a structure relating to a generated magnetic field of the coil; and a fourth step of calculating an eddy current or electric field induced inside each of the micro-polyhedron units on the basis of the first information provided in the third step and second information which includes conductivity assigned to each micro-polyhedron unit. Also disclosed is a transcranial magnetic stimulation device and system.

A transcranial magnetic stimulation is a technique of stimulating neurons by inducing an eddy current or an electric field in the brain through electromagnetic induction. In this technique, as shown in FIGS. 1 and 2, a current (e.g., alternating current) is applied to a stimulation coil placed on the skin of the head to form a variable magnetic field and to induce an eddy current or an electric field in the direction opposite to the coil current in the brain under the effect of the variable magnetic field, and an action potential is generated by stimulating the neurons with the eddy current or the electric field.
FIG. 3 shows an example of a stimulation coil drive circuit. In a principle of generating a momentary current in a coil, first, an electric charge is stored from a power source (including an alternating-current power source, a power circuit, and a booster circuit) into a capacitor. Subsequently, a thyristor is turned on to apply a current to a stimulation coil. The current is applied to a resonance circuit of the stimulation coil and the capacitor through a diode, and the thyristor is then turned off. As a result, a current corresponding to one cycle of a sine wave shown in FIG. 4 is applied to the stimulation coil.
The transcranial magnetic stimulation is used in clinical examinations and neuroscience including measurement of nerve conduction velocity.
In recent years, magnetic stimulation is gathering attention as therapeutic application to neuropathic pain, Parkinson's disease, depression, etc. A drug therapy may not effective to these diseases in some cases and methods of treatment in such a case include applying an electrical stimulation to the brain by implanting an electrode into the brain. However, this method requires a craniotomy and is therefore often not desired by patients. Thus, a repetitive transcranial magnetic stimulation performed by repeatedly applying a non-invasive magnetic stimulation not requiring a surgical operation is being studied as a method of treatment. For example, it is reported that a pain-relieving effect to intractable neuropathic pain is produced for about one day after magnetic stimulation to the primary motor cortex.
However, a conventional magnetic stimulation device weighs about 70 Kg and is available only in well-equipped medical institutions because electrical work is required for installation. Additionally, since a stimulation position is determined while referring to patient's MRI data during actual treatment, the treatment must be performed by a skilled health-care professional. In the treatment of intractable neuropathic pain, a coil is positioned on the target primary motor cortex with accuracy of 1 mm. However, to continuously acquire the pain-relieving effect, a patient must go to a medical institution every day. Therefore, a new magnetic stimulation device for home treatment shown in FIG. 5 has been developed that only requires an operation by a non-healthcare professional for utilization.

Intracerebral current simulation method and device thereof, and transcranial magnetic stimulation system including intracerebral current simulation device


A method for preparing crystalline cobalt nitrate. The method includes: 1) calcining a spent Co/SiO2 catalyst, cooling the calcined material to room temperature, and grinding it to yield a powder; 2) heating the powder in a fluidized bed reactor; 3) adding the heated powder into excess dilute nitric acid solution and filtering to obtain a cobalt nitrate solution; 4) adjusting the pH value of the cobalt nitrate solution to 1.5, adding a preheated oxalic acid solution, adjusting a pH value of the resulting solution to 1.5, immediately filtering the resulting solution to yield a precipitate of cobalt oxalate, washing the precipitate of cobalt oxalate to yield a neutral filtrate; 5) drying the precipitate and calcining to yield cobalt oxide; 6) dissolving the cobalt oxide in nitric acid to yield a second cobalt nitrate solution; and 7) evaporating the second cobalt nitrate solution to obtain crystalline cobalt nitrate.

1. Field of the Invention
The invention relates to a method for preparation of high purity, crystalline cobalt nitrate from spent Co/SiO2 catalyst.
2. Description of the Related Art
Cobalt is a rare metal. Silica supported cobalt-based Co/SiO2 catalyst is highly active in catalytic hydrogenation. Recycling cobalt from a cobalt-based spent catalyst decreases environmental pollution and improves the utilization of the cobalt resources.
A typical method for recycling cobalt includes precipitating cobalt ions to yield Co(OH)2, and dissolving Co(OH)2 in nitric acid to obtain Co(NO3)2.6H2O. However, the purity of Co(NO3)2.6H2O obtained by this method is less than 98%. In addition, the fine granules of intermediate CoS produced during the recycling process are difficult to filter, which causes cobalt loss during filtration and leads to a low recovery rate of cobalt.

Method for preparation of high purity, crystalline cobalt nitrate from spent cobalt/silica catalyst

Wuhan Kaidi Engineering Technology Research Institute Co., Ltd.


A toaster accessory is provided in the form of a pair of hinged foraminous panels forming a holder adapted to hold one or several slices of bread therebetween. In its preferred use, a sandwich is placed between the two panels and the holder, when closed, is dimensioned to fit into a conventional toaster so that a pre-made sandwich may be conveniently toasted therein. The hinge connection between the two panels is self-adjusting and a locking device at the opposite end is able to lock at different thicknesses. Decorative inserts may be added to the panels for making designs on the surface of the toasted bread.

1. Field of the Invention
This invention relates generally to toaster accessories and is especially directed towards an adjustable holder for sandwich, placed in the holder and toasted in a conventional toaster.
2. Description of the Prior Art
Various devices have been proposed heretofore for use in holding pieces of bread, muffins, hamburgers and the like for the purpose of toasting the same in a conventional electrical toaster. While such devices have worked satisfactorily for food products of specific sizes and shapes, they have been unsatisfactory in accommodating foods of different thicknesses which are to be toasted.
It is an object of the present invention to provide a new and improved holder for one or several pieces of bread which may be in the form of a sandwich for toasting the same in a conventional toaster.
Another object of this invention is to provide a sandwich holder adapted to self-adjust to a variety of different thicknesses of sandwiches placed therein for holding the same firmly together while toasting in a conventional toaster.


There is provided a system and method for statistical timing analysis and optimization of an electrical circuit having two or more digital elements. The system includes at least one parameter input and a statistical static timing analyzer and electrical circuit optimizer. The at least one parameter input is for receiving parameters of the electrical circuit. At least one of the parameters has at least one of a non-Gaussian probability distribution and a non-linear delay effect. The statistical static timing analyzer and electrical circuit optimizer is for calculating at least one of a signal arrival time and a signal required time for the electrical circuit using the at least one parameter and for modifying a component size of the electrical circuit to alter gate timing characteristics of the electrical circuit based upon the at least one of the signal arrival time and the signal required time.

It is commonly recognized that electrical characteristics of transistors and interconnects are not the same for different chips and even for the same chip at different time moments or chip locations. Variation of electrical characteristics can be due to variation of process parameters, changing of environmental conditions and even chips aging (Hot Carriers Injections, Negative Bias Temperature Instability, electromigration, and so forth). Variation of electrical characteristics results in variations of gate timing characteristics. The traditional conservative way to handle these variations is to consider so-called process corners at which the gates have the worst combinations of delays. Then chips are designed so that they can properly function at all process corners assuming that as a result they will function at any other combination of gate delays.
Unfortunately, with decreasing transistor size and interconnect width, the variation of electrical characteristics is getting proportionally larger. Therefore, the approach to design for process corners, which used to work well, now results in too conservative and non-optimal designs because most design efforts and chip resources are spent to make chips function at very low-probability combinations of electrical characteristics.
An alternative approach to designing chips as described above is to consider actual statistical characteristics of process parameter variations and use them to compute statistical characteristics of a designed circuit. For digital circuits, this approach is known as statistical timing analysis. There are several varieties of statistical timing analysis.
One of the most useful for circuit analysis and optimization is parameterized statistical static timing analysis (STA). According to this technique, gate delays and signal arrival times are represented as functions of process parameters.A=f(X1,X2, . . . )  (1)
All the parameters are assumed independent. This assumption significantly simplifies the analysis but does not limit its applicability because independence can be obtained by a principal component analysis technique. Using this representation, the parameterized STA computes a statistical approximation of the circuit timing characteristics (arrival and required arrival times, delay, timing slack) as functions of the same parameters.
The process parameters can be considered as either globally correlated or fully random. Both types of parameters exhibit variation due to the manufacturing process. The correlated parameters have the same values for all gates and wires of the analyzed circuit while the fully random parameters vary for each gate independently. Usually, it is convenient to combine all the fully random parameters into one term.
The parameterized statistical STA can be either path-based or block-based. Path-based statistical STA analyzes each signal propagation path separately and computes the probability distribution for circuit delay as the probabilistic maximum of all paths delays. Usually this requires enumeration of all signal propagation paths and integration in the space of parameters variations, which is an inefficient computational procedure.
A more efficient technique of parameterized STA is so-called block-based statistical STA. This technique is very similar to traditional deterministic STA. It computes signal arrival times (or signal required arrival times) as functions of process parameters for each circuit node in their topological order similarly to propagating arrival times by a deterministic STA. It is convenient for both implementation and application. That kind of statistical timing analyzer can be easily implemented on the base of existing deterministic timing analyzer. This type of timing analysis lends itself to incremental operation, whereby after a change of the circuit is made, timing can be queried efficiently.
For computational efficiency, parameterized statistical block-based STA assumes that all parameters variations have normal Gaussian distributions and that gate and wire delays depend on parameters linearly. Without loss of generality, Gaussian distributions with 0 mean and unit standard deviation are assumed. This assumption allows representation of gate delays in first-order canonical form, as described by C. Visweswariah in U.S. patent application Ser. No. 10/666,353, entitled "System and Method for Statistical Timing Analysis of Digital Circuits", filed on Sep. 19, 2003, incorporated herein by reference in its entirety (hereinafter referred to as the "System and Method for Statistical Timing Analysis of Digital Circuits patent"):
                    A        =                              a            0                    +                                    ∑                              i                =                1                            n                                                                                a                  i                                ·                Δ                                                                                X                i                                              +                                    a                              n                +                1                                                  Δ                                                                                R              a                                                          (        2        )            where: ao is a mean value; ΔXi is a variation of parameter Xi,
ΔXi=Xi−xo where x0 is the mean value of Xi; ai is the sensitivity of the gate delay to parameter variation ΔXi; ΔRa is a random variable responsible for uncorrelated variation of the gate delay; and an+1 is a sensitivity of the gate delay to uncorrelated variation ΔRn. The following United States patent applications, commonly assigned to the assignee herein, are incorporated by reference herein in their entireties: U.S. patent application Ser. No. 10/665,092, entitled "System and Method for Incremental Statistical Timing Analysis of Digital Circuits", filed on Sep. 18, 2003; U.S. patent application Ser. No. 10/666,353, entitled "System and Method for Statistical Timing Analysis of Digital Circuits", filed on Sep. 19, 2003; and U.S. patent application Ser. No. 10/666,470, entitled "System and Method for Probabilistic Criticality Prediction of Digital Circuits", filed on Sep. 19, 2003.
Sensitivity coefficients express dependency of a gate delay on a process parameter. The last coefficient expresses a fully random part of delay variation. Using unit Gaussian but not arbitrary Gaussian distributions simplifies the analysis but is not restrictive because parameter distributions can always be normalized, e.g., by accumulating their non-zero means into delay means and properly adjusting sensitivity coefficients.
Block-based STA computes arrival times at each circuit node using two basic operations: incrementing arrival time by a gate delay and computing worst-case arrival time. The incrementing of the arrival time by a gate delay corresponds to propagating signals from a gate input to its output. This operation is performed by summation of the arrival time at the gate input and gate delay. The computing of the worst-case arrival time selects the worst-case signal from the signals arriving at a gate's inputs. The worst signal can be the latest or the earliest one depending on the type of timing analysis. The computing of the worst-case arrival time is performed by computing the maximum or the minimum of several arrival times. Herein, only the case of computing the latest arrival time is discussed. However, it is to be appreciated that the proposed approach can be easily extended to computation of the earliest arrival time using obvious symmetry between minimum and maximum functions, while maintaining the spirit of the present invention.
In deterministic timing analysis, these basic operations are trivial. In the statistical case, the situation is more complex because expressions, and not simply numbers, are operated upon.
Using the first-order canonical form of gate delays and applying some approximation, it is possible to compute signal arrival times at circuit nodes and circuit delay in the same linear canonical form. Incrementing an arrival time by a gate delay given in the first-order canonical form Equation 2 is known. Incrementing the arrival time is performed by summing the corresponding sensitivity coefficients, as described in the System and Method for Statistical Timing Analysis of Digital Circuits patent and, thus, it is not considered herein.
The computation of the maximum of the two arrival times represented in the first-order form Equation 2 is significantly more difficult because the maximum is a non-linear function. Therefore, parameterized statistical STA computes an approximate first-order representation of the maximum of the two arrival times.
Linear and Gaussian assumptions are very convenient for statistical parameterized STA because it is possible to use approximate analytical formulae for computing canonical forms of arrival times. Analytical formulae make statistical timing analysis fast and computationally efficient, which is important for implementing a statistical approach in circuit synthesis and optimization. Unfortunately, process parameters may have probability distributions, which are significantly different from Gaussian. It is impossible to approximate certain asymmetric distributions by Gaussian ones with a reasonable error. For example, via resistance distributions are asymmetric. Another problem arises from the fact that some parameters can affect delay in a non-linear way. Usually a linear approximation is justified by assuming that process parameter variation and the corresponding delay variation is sufficiently small. However, with the reduction of transistor sizes, process variation is getting higher. Therefore, a linear approximation of delay dependence on variation is not always sufficiently accurate. For example, delay of a gate depends on transistor channel length non-linearly.
Accordingly, it would be desirable and highly advantageous to have a system and method for accommodating non-Gaussian and nonlinear sources of variation in statistical static timing analysis.

System and method for accommodating non-gaussian and non-linear sources of variation in statistical static timing analysis

International Business Machines Corporation


A heat-shrinkable article suitable for use as an insulating or coating material comprises a crosslinked composition of a polypropylene homopolymer or copolymer and an ethylene-propylene elastomer. The article is formed by a process comprising: i) creating a blend of the polypropylene homopolymer or copolymer and the ethylene-propylene elastomer by melt mixing; ii) melt processing the blend produced in i) to produce a melt processed material; iii) crosslinking the melt processed material produced in ii) by exposing it to radiation to produce a crosslinked material; iv) stretching the crosslinked material at a first temperature close to or above its softening or melting point and subsequently cooling it to a second temperature below its softening or melting point, to thereby freeze the crosslinked material in its stretched form. Subsequent heating of the article close to or above its softening point or crystalline melting point results in recovery of the pre-stretched dimensions of the article. Due to its relatively high content of polypropylene, the heat-shrinkable article thus produced has greater toughness and rigidity than polyethylene-based systems, making it suitable for use as insulation for wires and cables a heat-shrinkable corrosion resistant sleeves for high-temperature transmission pipeline joints, and for heat-shrinkable tubing or shapes for electrical insulation and mechanical protection.

The present invention relates to polymeric compositions and their uses, and more particularly to crosslinked compositions of polypropylene with ethylene-propylene elastomers, and their uses as coating and insulating materials, particularly those that are heat-shrinkable, but not necessarily restricted thereto.
Polypropylenes are ideally suited to the preparation of coatings and insulations designed for use at operating temperatures in excess of those that can be withstood by other polyolefins such as, for example, polyethylene, which exhibit lower softening and melting temperatures. Other attractive features are their high rigidity and toughness, low cost and relatively low density. Applications for these coatings and insulations would include polymeric insulation for electrical wires and cables, heat-shrinkable, corrosion protection sleeves for high-temperature transmission pipeline joints, heat-shrinkable tubing or shapes for electrical insulation and mechanical protection, or in applications requiring greater toughness and rigidity than is afforded by polyethylene-based systems. For example, heat-shrinkable sleeves used for the corrosion protection of high temperature pipeline joints are required to maintain dimensional stability and integrity at the operating temperature of the pipeline. Hence it is necessary to use a material, such as polypropylene, with a softening temperature or melting point high enough to prevent creeping or sagging of the sleeve from the pipe at the continuous operating temperature of the pipeline.
Also, in order to maximise thermal stability and physical properties, it is necessary to impart some thermoset characteristic to the material. This is done by crosslinking the polymer to some required degree. Crosslinking is also necessary for the production of heat-shrinkable articles in order to impart controlled shrinkage characteristics. The aim of this invention is to provide a means of preparing crosslinked, predominantly polypropylene-based, heat-shrinkable compositions, which can be used in the applications described, but not necessarily restricted thereto.
Polymers in which the predominant chain units comprise an alpha olefin, such as polypropylenes, are known to preferentially depolymerise or degrade when exposed to free radicals required to effect crosslinking. Hence, unlike similar materials, namely polyolefins such as polyethylenes and copolymers of polyethylene, it is not possible to crosslink polypropylene-based materials to satisfactory levels, as is required, for example, in the production of heat-shrinkable articles such as tubing, sheet, and moulded shapes, by using standard free-radical methods of crosslinking, such as electron beam irradiation, gamma irradiation, or peroxide-initiated crosslinking.
Work described in U.S. Pat. Nos. 3,717,559 and 4,424,293, for example, show that certain polypropylenes with the addition of acrylate crosslinking promoters can be crosslinked by irradiation to satisfactory levels for the production of polypropylene foam. However, the elastic strength and elongation of these materials at temperatures above the melting point have been found to be wholly insufficient to impart the high temperature resistance and controlled recovery characteristics required for the satisfactory production and performance of the heat-shrinkable products described above, and to confer the resistance to deformation and mechanical failure at elevated temperatures of electrical insulation, and similar, products. Hence it is necessary to resort to alternative methods to provide the necessary crosslinking of polypropylenes.
The present invention overcomes the above discussed problems of the prior art by providing a means whereby a predominantly polypropylene-based composition can be crosslinked by irradiation to the required level for the production of heat-shrinkable articles and functional high temperature insulation products by blending the polypropylene with a polymer that is highly sensitive to crosslinking by irradiation.
Hence, on crosslinking such a polymer blend, the radiation-sensitive component will preferably crosslink before the polypropylene can depolymerise to any great extent, and thereby form what may be termed as an interpenetrating crosslinked network with the predominantly uncrosslinked component. The crosslinking also acts to stabilise the blend through compatibilisation of the two relatively immiscible components by inducing a chemical interaction at the interface of the two components. As a result, the blend exhibits the properties of a crosslinked system whilst retaining the high temperature performance, stability and toughness of a predominantly polypropylene-based, semi-crystalline material. The crosslinked network allows the material to be heated close to or above the softening point without melting, such that it may be stretched a predetermined amount without rupture, and then frozen in the stretched state. Subsequent heating of the crosslinked, stretched material near or above the softening point will cause it to recover to approximately its original, unstretched dimensions.
In this invention, an ethylene-propylene elastomer, namely an ethylene-propylene copolymer (EPM) or, more preferably, an ethylene-propylene-diene terpolymer (EPDM), and, most preferably, an ethylene-propylene-diene terpolymer polymerised using metallocene catalysts (herein designated mEPDM), for example, the Nordel IP EPDM materials developed by DuPont Dow Elastomers L.L.C. using their INSITE(copyright) constrained-geometry catalyst technology, or a blend thereof, provides the necessary crosslinking sensitivity for blends with polypropylene.
The preferred mEPDM terpolymers, are prepared by copolymerising propylene with additional comonomers, specifically ethylene and a diene monomer usually chosen from 5-ethylidene-2-norbornene, dicyclopentadiene, or 1,4-hexadiene, using a highly stereospecific, single-site, constrained geometry, or so-called metallocene, catalyst. They differ substantially from existing EPDM materials produced using standard Ziegler Natta coordination catalysts in that it is possible to more accurately control the quantity and position of the comonomers within the polymer structure to provide a more precise molecular weight distribution and a more regular molecular architecture, resulting in higher crystallinity, for example, and superior material properties. More importantly with respect to the current invention, it is possible to adjust the comonomer levels for optimum sensitivity of the mEPDM to crosslinking by electron beam irradiation.
Suitable polypropylenes in this invention would include those materials commonly known in industry as polypropylene homopolymers, or polypropylene copolymers, the latter typically being copolymers of propylene and ethylene. Additionally, said polypropylene homopolymers include polypropylenes modified with reactive functional groups, such as acrylic acids, methacrylic acids, acrylates, methacrylates and anhydrides.
Alternatively, one or more additional materials may be incorporated to act as compatibilising or modifying agents for the ethylene-propylene elastomer and the polypropylene. Such materials would include the polypropylenes, EPM, EPDM and mEPDM materials described above; other ethylene-propylene elastomers; polyethylenes and copolymers of polyethylene, including those known in the industry as low density polyethylene, high density polyethylene, linear low density polyethylene, and those based on ethylene-butene, ethylene-hexene, ethylene-octene, ethylene-vinyl-acetate, ethylene-methyl-acrylate, ethylene-ethyl-acrylate, ethylene-butyl-acrylate, and similar materials, and particularly those prepared using metallocene catalysts; polyolefins modified with reactive functional groups, such as acrylic acids, methacrylic acids, acrylates, methacrylates and anhydrides; and block copolymers, such as styrene-butadiene, styrene-butadiene-styrene, styrene-ethylene/propylene and styrene-ethylene/butylene-styrene.
Blending of the polymeric, and any additional, constituents may be accomplished either in-situ with forming of the material during melt processing, or prior to forming, by melt mixing using a machine designed for that purpose, such as a continuous single or twin-screw compounder, kneader, or internal batch mixer.
The blended composition is formed into the desired article by melt processing techniques such as extrusion and moulding, including multi-layer processing, for example co-extrusion of the blend with another material to form discrete but intimately bonded layers. The article thus formed is then crosslinked by irradiation, for example with electron beam, gamma or ultra-violet radiation. The crosslinked article may be subsequently stretched at an elevated temperature and then frozen in the stretched state to create an article which can be recovered to its original unstretched dimensions on the application of sufficient heat. Examples of the aforementioned articles would include extruded tubing, sheet, and electrical insulation, and injection, compression or blow moulded insulating shapes, such as end caps and break-out boots, including heat-shrinkable versions of said examples.
Accordingly, in one aspect of the invention, a heat-shrinkable sheet is prepared by the process of: (a) melt blending a mixture of polypropylene copolymer with a metallocene-catalysed, ethylene-propylene diene terpolymer (mEPDM) and additional ingredients, such as radiation sensitizers, also known as crosslinking promoters, and antioxidant stabilisers, in a continuous compounder; (b) forming the pre-compounded material produced in (a) into a sheet by melt extrusion; (c) crosslinking the extruded sheet by subjecting it to radiation from an electron beam irradiator; (d) mechanically stretching the sheet at an elevated temperature; and (e) rapidly cooling the sheet whilst still in its stretched state.
In another aspect, the present invention provides a heat-shrinkable article comprising a crosslinked composition, said crosslinked composition comprising a polypropylene homopolymer or copolymer and an ethylene-propylene elastomer, said article being formed by a process comprising: i) creating a blend of the polypropylene homopolymer or copolymer and the ethylene-propylene elastomer by melt mixing; ii) melt processing the blend produced in i) to produce a melt processed material; iii) crosslinking the melt processed material produced in ii) by exposing it to radiation to produce a crosslinked material; iv) stretching the crosslinked material at a first temperature close to or above its softening or melting point and subsequently cooling it to a second temperature below its softening or melting point, to thereby freeze the crosslinked material in its stretched form.
The crosslinking of polyolefins, in particular polyethylene and copolymers of polyethylene, by means of radiation, and in particular by electron beam and gamma radiation, is a well-known and established process for confering high temperature resistance and for the production of heat-shrinkable articles. However, the use of this technology to the crosslinking of polypropylene is stymied by the preference of the polypropylene to depolymerise or degrade through the process of molecular chain scission when subjected to the levels of radiation required to confer the aforementioned properties for practical applications other than minor chain extensions required for the stabilisation of foamed products. This problem has been overcome in the present invention by blending the predominantly radiation-uncrosslinkable polypropylene with a predominantly radiation-crosslinkable ethylene-propylene elastomer, preferably an ethylene-propylene diene terpolymer.
The polypropylene used in the present invention may be selected from any of the classes known as polypropylene homopolymers or copolymers, being preferentially isotactic in nature, with a melt viscosity preferably similar to the ethylene-propylene elastomer with which it is melt blended.
The polypropylene is preferably added to the blend in the amount from about 10 to 90 percent, more preferably from about 20 to 80 percent, and most preferably from about 40 to 60 percent by weight of the blend.
The ethylene-propylene elastomer used in the present invention may be chosen from the class of materials known as ethylene propylene copolymers or elastomers (EPM), more preferably from those known as ethylene-propylene diene terpolymers or elastomers (EPDM), and most preferably from those ethylene-propylene diene terpolymers or elastomers polymerised using single-site or metallocene catalysts (mEPDM), or blends thereof. The ethylene-propylene elastomer is preferably selected to have a similar melt viscosity as the polypropylene at the same temperature and under the same shear conditions required for processing the blend.
Preferably, the ethylene propylene elastomers comprise about 40 to 95% ethylene, more preferably about 70 to 95% ethylene, and most preferably about 85 to 95% ethylene. The ethylene-propylene-diene terpolymers additionally comprise about 0.5 to 10% diene monomer usually chosen from 5-ethylidene-2-norbornene, dicyclopentadiene, or 1,4-hexadiene, and preferably 5-ethylidene-2-norbornene.
The ethylene propylene elastomer is preferably added to the blend in the amount from about 10 to 90 percent, more preferably from about 20 to 80 percent, and most preferably from about 40 to 60 percent by weight of the blend.
The polypropylene is melt blended with the ethylene-propylene elastomer, and, optionally, with one or more of a number of ingredients such as radiation sensitizers or crosslinking promoters, compatibilisers, pigmenting agents, antioxidants, heat stabilisers, uv stabilisers, mineral fillers, process aids and the like, to form a composition according to the invention.
The compatibiliser may be selected from one or more of the polypropylenes, EPM, EPDM and mEPDM materials described above; other ethylene-propylene elastomers; polyethylenes and copolymers of polyethylene, including those known in the industry as low density polyethylene, high density polyethylene, linear low density polyethylene, and those based on ethylene-butene, ethylene-hexene, ethylene-octene, ethylene-vinyl-acetate, ethylene-methyl-acrylate, ethylene-ethyl-acrylate, ethylene-butyl-acrylate, and similar materials, and particularly those prepared using metallocene catalysts; polyolefins modified with reactive functional groups, such as acrylic acids, methacrylic acids, acrylates, methacrylates, and anhydrides; and block copolymers, such as styrene-butadiene, styrene-butadiene-styrene, styrene-ethylene/propylene and styrene-ethylene/butylene-styrene.
The function of the compatibiliser is to promote the miscibility of the polypropylene and ethylene-propylene elastomer when they are blended together. The compatibiliser is preferably added in the amount from about 1 to 50% and most preferably from about 5 to 10% by weight of the blend. Addition of a compatibiliser will not be necessary where the polypropylene and ethylene-propylene elastomer exhibit satisfactory natural miscibility.
The radiation sensitizer or crosslinking promoter, if required, may be preferably selected from the family of multifunctional acrylate or methacrylate monomers typically used as crosslink promoters for polyolefin-based polymers. Preferred monomers would include trimethylol propane triacrylate, trimethylol propane trimethacrylate and tetramethylol tetraacrylate. The radiation sensitizer would be added in the amount from about 0.25 to 2.5%, and preferably 0.5 to 1.5% by weight of the blend. The function of the radiation sensitizer is to render the polymer composition more susceptible to crosslinking by electron beam (beta), or gamma radiation, hence allowing a given level of crosslinking to be achieved with less radiation dosage and energy than if a sensitizer were not used. Addition of the crosslinking promoter will not be necessary if the polymer blend by itself is sufficiently sensitive to irradiation to achieve the required degree of crosslinking.
The antioxidant stabiliser may be chosen from any suitable antioxidant or blend of antioxidants designed to prevent degradation of the polypropylene-based blend during melt processing and subsequent heat aging of the final product. Examples of suitable antioxidant and process stabilisers would include those classes of chemicals known as hindered phenol antioxidants and phosphite stabilisers. These would typically be added in an amount from about 0.1 to 5% by weight of the blend depending upon the aging properties required and the type and quantity of additional destabilising ingredients in the composition, for example halogenated flame retardants or mineral fillers. It should also be noted that these antioxidants, if added in sufficient amounts, will act as xe2x80x9cradiation scavengers,xe2x80x9d reducing the effectiveness of the radiation to induce the desired crosslinking reaction and tending to reduce degree of crosslinking obtainable for a given radiation dosage.
The above constituents of the blend may be melt blended either in-situ with forming of the final product during melt processing, or prior to forming by melt mixing using a machine designed specifically for that purpose, such as a continuous twin-screw compounder, kneader, or internal batch mixer.
A particularly preferred process for preparing a radiation-crosslinkable polypropylene based article is described below:
A polypropylene copolymer and a mEPDM elastomer along with a radiation sensitizer, antioxidant stabiliser and pigmenting agent, are melt blended in a Buss reciprocating-screw kneader, continuous compounder, at a temperature above the melting point of the composition, to form a fully dispersed compound which is then pelletized and stored for subsequent processing.
The pelletized compound is then melt processed, for example extruded, co-extruded, or moulded, to the desired article. The article so produced is then crosslinked by subjecting it to electron beam radiation of approximate dosage between 1 and 15 megarads in an electron beam accelerator, for example a xe2x80x9cDynamitronxe2x80x9d manufactured by Radiation Dynamics Inc. The dosage used is dependent upon the final properties of the article required. Too low a dosage will result in the article having a low degree of crosslinking, poor mechanical toughness and a tendency to prematurely soften or melt at elevated temperatures. Too high a dosage may result in degradation of the polypropylene component with a resultant unacceptable deterioration in mechanical properties. A preferred dosage has been found to be around 5 megarads for the manufacture of heat-shrinkable articles.
The article thus produced exhibits the property of softening but not melting when re-heated above its softening point or crystalline melting point. This is desirable for the manufacture of heat-shrinkable articles, since the polymer may be stretched beyond the original extruded or moulded dimensions without rupture using relatively low forces, and can then be frozen in the stretched state by cooling it rapidly to below the softening or melting point. Stretching can be accomplished by mechanical, pneumatic or hydraulic means. At this point the stretched crosslinks are held in a stable state by the re-formed, solid crystalline regions of the polymeric components. Subsequent re-heating of the stretched article above the melting point will cause the crystalline regions to re-melt and the structure to revert to its original extruded or moulded dimensions. The crosslinking also prevents the article from becoming liquid during this shrinking process.
The invention is further illustrated by the following examples:

Crosslinked, heat shrinkable polypropylene compositions


A method and apparatus are provided for establishing a split-terminated client-server communication connection through a stateful firewall, with network transparency. In an environment in which a pair of network intermediaries is employed to optimize client-server communications, a first intermediary intercepts a client request for a new connection. The first intermediary probes the network for a counterpart near the server, and opens an optimized communication session with a second intermediary that responds affirmatively. Some or all client-server communications that transit the intermediaries' session are accelerated or otherwise optimized. The first intermediary's probe uses the client's source address, but a different port number, while the optimized intermediary session is opened using the client's source address and source port. Therefore, a network monitoring tool can monitor the end-to-end connection, and the stateful firewall will not reject the optimized session.

End-to-end communication connections such as those conducted between a client and a server can often be optimized for more efficient and/or rapid transit across a WAN (wide-area network) or other long-haul communication link, such as the Internet. Such optimization is typically performed by a pair of transaction accelerators installed within the path of communication, wherein the accelerators manipulate communications as appropriate to reduce the amount of data that must be conveyed.
For example, a transaction accelerator such as that described in U.S. Pat. No. 7,120,666 (McCanne) can offer performance improvement for 25 operations across a WAN when the data being communicated is either intelligible (i.e., the transaction accelerator can interpret at least parts of the protocol) or repeating (i.e., identical data crosses the network in identical format).
Illustratively, a client-server connection (or other end-to-end communication connection) may be split-terminated at the accelerators, with one of the accelerators receiving messages from the client, manipulating them and forwarding them to a cooperating accelerator. That accelerator processes the communications (e.g., to recover the original messages), then forwards them to the server. Communications passing in the reverse direction are processed similarly. Thus, the overall client-server connection is split into multiple separate sessions.
However, the manner in which transaction accelerators configure their optimized communications may impact other aspects of an organization's networking environment. For example, a transaction accelerator may use its own network address when communicating with another accelerator, but an address of the server or the client when communicating with the client or the server.
More specifically, an accelerator that receives messages from a client may proxy for the server to receive messages directed to the server and to deliver to the client messages originated by the server. Likewise, the other accelerator may proxy for the client to exchange messages from the server. Between themselves, however, the accelerators may exchange optimized communications using their own network addresses.
This scheme usually frustrates an organization's desire for network transparency, which would allow the organization to track communications throughout its network and attribute them to the appropriate endpoints (e.g., client and server). If the organization cannot track communications from one end to another, they may be unable to effectively monitor their network traffic, determine the effectiveness of the transaction accelerators, promote desired Qos (Quality of Service), ensure effective load-balancing, and so on.
However, enabling network transparency is not as simple as using the network addresses of the client and server throughout the split-terminated sessions established by the transaction accelerators. For example, each time an accelerator receives a request from a client for a connection with a server, it must determine whether there is a cooperative accelerator available in the vicinity of the server. If not, the connection cannot be optimized and the client and the server should be allowed to communicate as they would without transaction accelerators.
However, if there is an available server-side accelerator, then the accelerators can perform their optimization. But, they must configure their communications to avoid any possibility of corrupting other data passing between the endpoints. For example, if the server-side accelerator were to fail, communications directed to it from the other accelerator would then be received directly at the server. If the accelerators' communication session could not be differentiated from other connections, the endpoint may accept their data within a different connection and suffer from data corruption.
Further, if a stateful firewall is interposed between the transaction accelerators, their ability to open multiple communication sessions using the same network addresses may be limited. For example, if the accelerators use addresses of the client and the server in order to promote network transparency, a firewall may deny any attempt to open a second connection between the same pair of addresses while a first connection is still open.

Establishing a split-terminated communication connection through a stateful firewall, with network transparency


A new disk system is connected to a switch that has been already connected to a host and old disk system. At that time, the new disk system is assigned in advance a port ID of the same value as the port ID that has been assigned to the F—Port of the switch, so that the new disk system will not be recognized from host 101. The new disk system read the configuration information of the old disk system. Then, in the switch, physical port ID 602 of old disk system 103 and physical port ID 602 of new disk system 104 are exchanged. The new disk system constructs volumes corresponding to the logical volume numbers and sizes of those volumes in the old disk system, and stores data of the old disk system in the corresponding volumes.

1. Field of the Invention
The present invention relates to a method of additionally attaching a new disk system (migration destination disk system) to a storage area network (hereafter referred to as SAN) and migrating data from an old disk system (migration source disk system), which is already connected to the SAN, to that new disk system and a device thereof.
2. Description of Related Art
Conventional computer systems are configured with a plurality of servers connected by a network such as a LAN and disk units are directly connected to each computer. The data inside each disk unit was managed by the directly connected server. In other words, data was managed in a distributed condition.
However, the SAN which adopts a configuration in which a plurality of servers, a plurality of disk units, backup units, etc. are connected by a switch or hub has recently become a hot topic. Fiber channels are used to physically connect these units to a switch or hub. The advantages of configuring a system using a SAN are superior scalability and the realization of reduced management cost since unified management can be performed by integrating data distributed over a plurality of disk units. Consequently, a SAN is well suited to a large-scale system. Because many resources are interconnected with a SAN, the management of these resources is an important topic. The management of a logical volume (such as backup), as the management of a disk unit, is one example of that. At present, these management methods are being studied by the SNIA (Storage Networking Industry Association) and NSIC (National Storage Industry Consortium).
On the other hand, U.S. Pat. No. 5,680,640 discloses a system and method of migrating data from a first data storage system to a second data storage system. A summary of that is as follows. A first data storage system already connected to a host, network or other data processing system is detached from the aforementioned host and connected to a second data storage system. The aforementioned second data storage system is connected to the aforementioned host or aforementioned data processing system. The aforementioned second data storage system contains a data map or data table that indicates which data element is stored in the aforementioned second storage system and which data in the aforementioned first data storage system has been copied to the aforementioned second storage system. When the aforementioned host, aforementioned network or aforementioned data processing system issues a request for data to the aforementioned second storage system, the aforementioned second data storage system judges whether that data has been stored in the aforementioned second data storage system or in the aforementioned first storage system. If the data has been stored in the aforementioned second data storage system, that data can be used by the host, etc. If the data is not stored in the aforementioned second data storage system, the aforementioned second data storage system issues a request to the aforementioned first data storage system, and that data can be used by the aforementioned host, etc. Then, the aforementioned second data storage system writes that data to its own system and updates the aforementioned data map or aforementioned data table. When the aforementioned second data storage system is not busy, it scans the aforementioned data map or aforementioned data table, determines which data of the aforementioned first data storage system has not yet been copied into its own system, and executes the copying of that data and updating of the aforementioned data map or aforementioned data table.
According to the data migration system and method disclosed in U.S. Pat. No. 5,680,640, independent from the aforementioned host, it is possible to execute data migration from the aforementioned first data storage system to the aforementioned second data storage system.
However, in the aforementioned data migration system and method, when the aforementioned second data storage system is utilized, the procedure of detaching the aforementioned first data storage system from the aforementioned host, connecting it to the aforementioned second data storage system, and connecting the aforementioned second data storage system to the aforementioned host is necessary. Consequently, at least during the interval beginning when the aforementioned first data storage system is detached from the aforementioned host until the aforementioned second data storage system is connected to the aforementioned host and the aforementioned first storage system, the aforementioned host cannot issue I/O (Input/Output) requests. In addition, during that interval it is necessary to temporarily suspend applications or other programs on the aforementioned host that use the aforementioned first data storage system. To further suppress costs associated with data migration, it is necessary to further reduce the time when I/O requests cannot be issued and the time when applications are suspended.
In addition, in the aforementioned data migration system and method, to connect the aforementioned first data storage system to the aforementioned second data storage system, a channel must be newly provided to each data storage system.
Further, in U.S. Pat. No. 5,680,640, a data migration system and method in a SAN environment are not disclosed.

Data migration method using storage area network


An electrostatic thermal bonding method for bonding a pair of glass substrates, is capable of solving the problems such as a contamination of a device and incomplete vacuum packaging due to gas generated during the bonding of glass substrates utilizing a conventional epoxy or frit. The electrostatic thermal bonding method uses a silicon-glass bonding mechanism. First, a silicon thin film is deposited on a metal thin film formed on a side of one glass substrate, and the two glass substrates are brought face to face with each other by bringing the silicon thin film into contact with the surface of the other glass substrate. A predetermined direct current voltage is applied between the metal thin film and the other glass substrate under a predetermined temperature, thereby the bonding between glass substrates is performed. In the glass-glass bonding method utilizing the silicon thin film, the direct current voltage in the range of 0 to 1000V is applied under a bonding temperature between 100 to 500.degree. C. and the elements are combined between a surface of the glass and a surface of the silicon thin film. Therefore, such a bonding results in an improved bonding strength and an improved vacuum packaging.

1. Field of the Invention
The present invention is directed to an electrostatic thermal bonding of glass substrates, and in particular to an improved electrostatic thermal bonding method capable of easily and solidly bonding a pair of glass substrates without using an adhesive or a high-temperature process.
2. Description of the Background Art
An electrostatic thermal bonding method was introduced in 1969, and then a silicon-glass bonding and a silicon-silicon bonding utilizing a glass thin film have been used in packaging of miniature devices. The thermal expansion coefficient of a glass used for the electrostatic thermal bonding is almost identical with that of a silicon, and materials containing metallic elements therein having a remarkable ionization tendency such as natrium and lithium are used for the glass to be bonded. For the silicon-glass bonding, when the silicon substrate and glass substrates are brought face to face with each other and heated to a predetermined temperature, and then the metal elements inside the glass substrates are ionized into the ionic condition having constant electric charges. Here, in the case that an external direct current voltage of a cathode is applied to the glass substrates, the ionized metal ions are moved into the cathode due to the electric field generated at both end portions of the silicon-glass interface and a space charge section is formed at the interface of the silicon-glass. A strong electrostatic force is generated due to the space charges. The silicon and the glass substrates are forced to be pulled toward each other by the electrostatic force, and thus a bonding of the silicon and the glass substrates is performed.
However, in the case of a flat-plate display device, the bonding of the two glass substrates is conventionally performed utilizing a method for bonding a pair of glass substrates by putting glass frit on a surface of one glass substrate, facing the pair of substrates to one another, and heating the glass substrates to a temperature of about 450 to 600.degree. C. for melting the glass frit, whereby the pair of glass substrates are bonded
As mentioned above, the conventional electrostatic thermal bonding methods have been limited to a silicon-glass bonding and silicon-silicon bonding utilizing a glass thin film. That is, the conventional electrostatic thermal bonding methods have not been adopted for a glass--glass bonding related to a display device.
In the studies recently performed with regard to the packaging of flat-plate display devices, a glass--glass bonding using a glass frit is utilizing for bonding glass substrates. However, such a packaging, i.e., the conventional glass--glass bonding method has disadvantages in that the longevity of the device is reduced due to the high temperature bonding and the device is contaminated by gas generated during the melting of the glass frit, which results in inferior effect on the condition that a vacuum packaging should be performed.

Method for electrostatic thermal bonding of a pair of glass substrates by utilizing a silicon thin film


A method for monitoring consumable performance in a processing tool comprises storing a performance model of the processing tool; receiving a consumable item characteristic of a consumable item in the processing tool; determining a predicted processing rate for the processing tool based on the consumable item characteristic and the performance model; determining an actual processing rate of the processing tool; and determining a replacement interval for the consumable item based on at least the actual processing rate. A processing system includes a processing tool and an automatic process controller. The processing tool is adapted to process wafers and includes a consumable item.

1. Field of the Invention
This invention relates generally to semiconductor device manufacturing, and, more particularly, to a method and apparatus for monitoring consumable performance in a processing tool.
2. Description of the Related Art
The manufacture of most devices, such as semiconductor devices, requires a number of discrete processing steps to create the device. With respect to semiconductor devices, a number of discrete steps are needed to produce a packaged semiconductor circuit device from raw semiconductor material. The starting substrate is usually a slice of single crystal silicon referred to as a wafer. Circuits of a particular type are fabricated together in batches of wafers called xe2x80x9clotsxe2x80x9d or xe2x80x9crunsxe2x80x9d. The fabrication process creates regular arrays of a circuit on the wafers of a lot. During processing, the individual wafers in a lot may go through individual processing steps one at a time or as a batch. At the completion of wafer processing, the wafers are tested to determine circuit functionality. Later, the wafers are cut to separated the individual integrated circuit devices, the functioning devices are packaged, and further testing is performed prior to use by the customer.
Various processing tools used in the production of the semiconductor devices employ consumable items that are gradually depleted over their service lives. This depletion affects the performance of the tool in which they are employed. Often, periodic adjustments to the operating recipes of the tools are required to compensate for the degraded performance of the tool. Generally, these adjustments increase the time required to process the wafers in the tool.
One particular tool employing consumable items is a chemical mechanical polishing (CMP) tool. In a CMP process, the upper surface of a layer previously formed on a wafer is planarized to ease formation of subsequent process layers. Chemical mechanical polishing typically uses an abrasive slurry disbursed in an alkaline or acidic solution to planarize the surface of the wafer through a combination of mechanical and chemical action. Generally, a CMP tool includes a polishing device positioned above a rotatable circular platen or table on which a polishing pad is mounted. The polishing device may include one or more rotating carrier heads to which wafers may be secured, typically through the use of vacuum pressure. In use, the platen may be rotated and an abrasive slurry may be disbursed onto the polishing pad. Once the slurry has been applied to the polishing pad, a downward force may be applied to each rotating carrier head to press the attached wafer against the polishing pad. As the wafer is pressed against the polishing pad, the surface of the wafer is mechanically and chemically polished. Both the polishing pad and the carrier heads are subject to gradual deterioration. This degradation gradually decreases the polishing rate of the CMP tool over the life of the pad and carriers. Eventually, a polishing pad may fail catastrophically and cease to polish entirely. To respond to this degradation, certain process parameters may be modified. For example, the polishing time parameter in the operating recipe of the CMP tool must be periodically increased over time. Additionally, the down force applied by the carrier heads may be varied. After a predetermined number of wafers have been polished or after a specified time interval, the polishing pad and/or carrier heads are replaced.
Another exemplary tool employing consumable resources is a sputtering deposition tool. A sputtering tool uses a metal source, commonly referred to as a target, and bombards the source with energized ions, causing particles of the metal to be displaced and deposited on the surface. Over time, characteristics of the target, such as surface porosity, change due to the repeated physical bombardment. As a result the deposition rate decreases over time, and the operating recipe of the sputtering tool is periodically updated to increase the deposition time over the life of the target. Generally, sputtering targets are replaced on fixed intervals, such as after processing a predetermined number of wafers. The actual degradation rate experienced by individual targets may vary. Replacement intervals are generally selected to account for nearly the worst case degradation rate. As a result, certain targets are replaced before their useful life has been exhausted. Certain sputtering targets, such as gold, are costly. Premature retiring of such expensive targets is inefficient. On the other hand, as the deposition time is increased to account for the degradation in the target, there may come a point where the deposition time in the sputtering tool affects the overall critical path of wafers in the processing line. At such a point, the costs saved by keeping the target in service may be negated by the costs incurred as a result of delays in the processing line. Additionally, with very long replacement intervals, the entire target can be depleted in places and require immediate replacement to maintain the quality and composition of the deposited metal. The use of a fixed replacement interval attempts to find a compromise balancing these concerns.
In both exemplary cases described above, and in others not mentioned, the performance of the consumable items affect the operation of the individual processing tool as well as the efficiency of the processing line in which they participate. The use of fixed replacement intervals for consumable items is not always an effective solution for optimizing tool and line efficiency.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
One aspect of the present invention is seen in a method for monitoring consumable performance in a processing tool. The method comprises storing a performance model of the processing tool; receiving a consumable item characteristic of a consumable item in the processing tool; determining a predicted processing rate for the processing tool based on the consumable item characteristic and the performance model; determining an actual processing rate of the processing tool; and determining a replacement interval for the consumable item based on at least the actual processing rate.
Another aspect of the present invention is seen in a processing system including a processing tool and an automatic process controller. The processing tool is adapted to process wafers and includes a consumable item. The automatic process controller is adapted to store a performance model of the processing tool, receive a consumable item characteristic of the consumable item in the processing tool, determine a predicted processing rate for the processing tool based on the consumable item characteristic and the performance model, determine an actual processing rate of the processing tool, and determine a replacement interval for the consumable item based on at least the actual processing rate.

Method and apparatus for monitoring consumable performance


Provided is an aqueous polyurethane emulsion composition having a urethane-urea bond, which is obtained by reacting a polyisocyanate, a polyester polyol and an ionic compound to prepare a polyurethane prepolymer, neutralizing it with an alkali or trialkylamine, dispersing it in water and reacting it with an amine, which is a chain extender. Polyurethane gloves manufactured with the aqueous polyurethane emulsion composition of the present invention have superior antistatic property, which is maintained even after washing, and wearing comfort similar to that of gloves made of natural latex and do not cause allergic reactions.

Antistatic property is very important in clean rooms. Static electricity causes contamination by dusts and failure and deterioration of electronic devices due to ESD (electrostatic dissipative) discharge. When charged dusts floating in the air approach a charged object, they are attracted by the object due to electrostatic induction and contaminate it. When static electricity charged in the human body or an object is discharged to an electronic device, discharge current passes through the low-resistance region of the device (see Table 1). Heat energy resulting from the current causes such problems as thermal failure of microchips. Particularly, although an operator does not sense the discharge voltage when it is 3.5 kV or below, an electronic device may suffer a severe damage.
As semiconductor products are becoming faster and less power-consuming, wirings and metal electrodes are becoming ever smaller and oxide insulator films are becoming thinner, for the purpose of circuit integration. Resultantly, even heat produced by a small electrostatic discharge current can lead to electrostatic failure of circuits. When a semiconductor product has been completely failed, it may be detected before it is shipped. But, a product slightly deteriorated by relatively small static electricity is hardly detected during shipment inspection.
In order to prevent these severe problems caused by static electricity, a variety of measures are taken, including earthing machines, apparatuses and equipments susceptible to static electricity, using antistatic-treated materials, using conductive materials, humidifying and installing static eliminator.
Especially, an operator wears an antistatic suite, antistatic shoes, antistatic gloves, etc. in order to minimize static electricity caused by the operator. Antistatic gloves are particularly important because they directly contact devices. Wearing antistatic gloves helps prevent contamination of devices and reduce electrostatic failure. Natural rubbers, synthetic rubbers (NBR), polyvinyl chlorides (PVC), etc. are currently used as materials for antistatic gloves. Natural rubber gloves have very poor antistatic property and tend to cause allergic reactions. Synthetic rubbers (NBR) also have insufficient antistatic property and are not completely free from allergic reactions. Polyvinyl gloves may cause contamination of devices because of migration of plasticizers and is disadvantageous in overall properties, including poor antistatic property, mechanical property and wearing comfort. Thus, gloves capable of offering superior antistatic property, wearing comfort, prevention of allergic reactions, mechanical property, etc., compared with the existing gloves, are needed.
TABLE 1Electrostatic sensitivity of electronic devicesESD voltage range causing failureDevice typeVoltage (V)Energy (μJ)VMOS 30-1800MOSFET100-200 0.5-2.0 EPROM1000.5JFET140-17000.98-2.45 OP-AMP190-25001.62-312.5 CMOS250-30003.13-450  Schottky diode300-25004.5-312.5Film register300-30004.5-450  Bipolar transistor100-70004.5-2.45 Schottky TTL1000-2500  50-312.5
Table 2 shows electric property based on surface resistance values according to ASTM D257. If the surface resistance is 1012 Ω/sq or larger, static electricity tends to form easily because charging is difficult. If the surface resistance is too small, spark may occur. When the surface resistance is 1010 Ω/sq or smaller, static electricity built up in a body decays almost instantly. When it is about 1012 Ω/sq, it takes a few seconds for the static electricity to decay, and several minutes at 1014 Ω/sq. Consequently, the best surface resistance range is from 105 Ω/sq to 1010 Ω/sq.
TABLE 2Electric property and surface resistanceClassificationSurface resistance (in ohms/square)Conducting<1 × 103 Chargeable<1 × 1012Insulating>1 × 1012
The present inventors succeeded in manufacturing antistatic gloves using a polyurethane showing physical properties comparable to those of a natural rubber and offering superior antistatic property. Manufacture of polyurethane gloves was disclosed in WO 00/61651 and WO 01/55237. In these patents, polyurethane was synthesized from a polyether polyol by forced emulsification using an external emulsifier, without introducing an ionic group inside the polyurethane. The resultant polyether type urethane gloves have poor hydrophilicity compared with the polyester type. Because an ionic group, which offers hydrophilicity, was not introduced, it has high surface resistance and poor antistatic property, as well as weak hydrophilicity. Although an external emulsifier was introduced to improve hydrophilicity, it is easily washed away by water, differently from the ionic group introduced inside the molecule. Resultantly, antistatic property of the film surface is significantly reduced after washing.
WO 01/88024 disclosed an aqueous polyurethane emulsion prepared by introducing a salt ion, a conductivity inducing material, into a polyether polyol by forced emulsification, in order to improve antistatic property. However, a film prepared using the same does not offer sufficient antistatic property.

Aqueous polyurethane emulsion composition and polyurethane film using the same


A treadmill with an endless belt forming a movable surface to walk or run on. The novel supports for the endless belt suspend it from the periphery of its uppermost surface. Two large rollers within the endless belt suspend it and allow it to be moved longitudinally. Two banks of small rollers mounted along the top edges of the frame form the lateral supports. These rollers engage the edges of the endless belt to suspend it laterally within the exercise area.

1. Field of the Invention
The present invention relates to treadmills. More specifically, the present invention relates to a treadmill with an endless belt that is suspended longitudinally and laterally, so that it can deflect downwards to absorb the impacts of a person walking or running on it.
2. Prior Art
Conventional treadmills provide a moving surface in the form of an endless belt traveling over a low friction surface between two rollers, so that a person can walk or run in a confined space. The low friction surface of the conventional treadmill is supported by a rigid unyielding frame. Sustained exercise of a type whereby the feet strike rigid, unyielding surfaces is popularly known as "high impact." High impact exercises have been proven to cause stress fractures, and other disabling injuries for some participants and many people cannot engage in any high impact activities because they could aggravate pre-existing conditions and/or hinder the rehabilitation of injuries.
Treadmills have been devised with yielding support structures under the endless belt such as the Treadmill Exercising Device with Yieldable Belt Support of Hagen U.S. Pat. No. 3,689,066 and the Exercise Treadmill Shock-Absorbing Improvement of Hanford U.S. Pat. No. 4,350,336. However, superior shock absorption capabilities are demonstrated by Lee et al with the Treadmill with Trampoline-Like Surface U.S. Pat. No. 4,548,405. This treadmill suspends the endless belt longitudinally between two rollers and laterally by a moveable spring suspension system over an essentially open frame. This complex suspension system supports the endless belt laterally by a plurality of springs attached along its edges. These springs are allowed to move with the endless belt by brackets containing rollers with anti-friction bearings that follow continuous tubular rails attached rigidly to the frame of the treadmill.
In the use of the Treadmill with Trampoline-Like Surface, it has been found that for best performance, the spring-carrying rollers must be made of a hard, low friction plastic such as acetal with Teflon.RTM., and that the continuous rails be fabricated from a polished, seamless, corrosion resistant material such as high-grade stainless steel tubing. If inferior materials are used, the overall friction of the system becomes too great for a person to walk or run without the aid of a powerful electric motor. Additionally, a film of light oil must be maintained on these continuous railings to produce an acceptable level of mechanical efficiency.
The painstaking fabrication of these continuous railings, and the complexity of the spring-carrying roller brackets, results in a much higher cost of manufacture than conventional treadmills. Also, the continuous rails force the spring-carrying roller brackets to make 180 degree turns as they follow the endless belt at speeds up to 10 MPH. The rapid and constant nature of these directional changes gives the Treadmill with Trampoline-Like Surface a much higher operating noise level than any conventional treadmill, which is objectional in many health-care facilities.


An aircraft includes a fuselage and a wing extending from each lateral side of the fuselage. A nacelle is pivotably se cured to each wing. The nacelle has a rotor located thereat, with the rotor having a rotor tip path plane defined by rotation of the rotor about a rotor axis of rotation. When the rotor tip path plane is changed relative to the wing, the nacelle pivots relative to the wing about a nacelle hinge axis to reduce flapping required by the rotor. A method of operating an aircraft includes changing a rotor tip path plane orientation relative to a wing of the aircraft. The rotor disposed at a nacelle, with the nacelle pivotably secured to the wing. The nacelle is pivoted relative to the wing to reduce an overall tip path plane change requirement of the rotor.

The subject matter disclosed herein relates to vertical takeoff or landing (VTOL) aircraft, such as tilt wing aircraft or Rotor Blown Wing (RBW) aircraft. More specifically, the present disclosure relates to VTOL aircraft having cyclic rotor control.
VTOL aircraft are rotor-driven aircraft capable of transitioning between conventional wing-borne flight, also referred to as airplane mode, and rotor borne flight, also referred to as helicopter mode. In some configurations, the VTOL aircraft is a tilt wing aircraft, in which the wings and rotors mounted at the wings are rotatable relative to the fuselage. In other configurations, the VTOL aircraft is a tail-sitter aircraft, in which the fuselage, wings and rotors all rotate together to transition between airplane mode and helicopter mode. Such aircraft have increased flexibility over many other aircraft in that they are capable of vertical takeoff and/or landing and have increased maneuverability due to their ability to operate in both airplane mode and helicopter mode.


The present invention encompasses a cancer vaccine therapy targeting Aspartyl-[Asparaginyl]-,8-hydroxylase (HAAH). The present invention contemplate bacteriophage expressing HAAH peptide fragments and methods for using said bacteriophage in methods of treating cancer.

Cancer is one of the most devastating diseases both in terms of human life opportunity loss and health care cost. It also presents unmet clinical needs. Currently available chemotherapies have limited efficacy and limited target patient population. Even the successful immunotherapies have shortcomings similar to chemotherapies. Moreover, essentially all cancer therapeutics have significant adverse side effects.
Aspartyl-(Asparaginyl)-β-hydroxylase (HAAH) is over expressed in various malignant neoplasms, including hepatocellular and lung carcinomas. HAAH is a tumor specific antigen, which is specifically expressed on the surface of certain malignant cells. HAAH is a hydroxylation enzyme that modifies factors such as Notch that contribute to cancer etiology by causing cell proliferation, motility, and invasiveness. Neutralizing the enzyme or reducing its expression leads to normal phenotype(s) in cancer cells. Anti-HAAH antibodies (as well as siRNA) have been shown to be cytostatic. An all-human sequence anti-HAAH (PAN-622) has shown to inhibit tumor growth by more than 90% in animal studies by passive immunotherapy. However, HAAH is well conserved and is also over expressed in placenta hence it is not sufficiently immunogenic in animals and it is certainly a self antigen in humans.
A vaccine therapy targeted to a pan-cancer-specific antigen such as HAAH that has proven relevance to cancer etiology is very desirable. Its economic impact will be enormous both in terms of job creation and increased productivity as well as in savings in health care and extending productive lives. The vaccine therapy of the present invention is novel both in terms of its target and the vaccine entity.

Therapeutic cancer vaccine targeted to HAAH (aspartyl-[asparaginyl]-beta-hydroxylase


An apparatus for effecting a control action in respect of a function within a virtual or mixed reality system, the control action corresponding to a predefined bodily movement of an authorized user of said function, wherein an authorized user is defined by a predetermined criterion in respect of a selected body part and/or a passive device carried thereon. The apparatus comprises a detection module for detecting a predefined bodily movement; a multi-spectral imaging system for capturing spectral reflectance and/or emission data at a plurality of wavelengths in respect of said selected body part and/or the passive device carried thereon; and an analysis module for comparing at least a portion of the spectral data with data corresponding to an authorized user of said function to determine if said criterion is met, and outputting a signal to effect said control action only if said criterion is met.

Virtual reality systems are known, comprising a headset which, when placed over a user's eyes, creates and displays a three dimensional virtual environment in which a user feels immersed and with which the user can interact in a manner dependent on the application. For example, the virtual environment created may comprise a game zone, within which a user can play a game.
More recently, virtual reality systems have been developed which enable "screens" of information, derived from multiple data sources, to be displayed within a three-dimensional virtual room, such that when a user places the headset over their eyes, they feel immersed within a virtual room having multiple data sources displayed simultaneously in three dimensions.
More recently, augmented and mixed reality systems have been developed, an image of a real world object can be captured, rendered and placed within a 3D virtual reality environment, such that it can be viewed and manipulated within that environment in the same way as virtual objects therein. Once again, it is envisaged, that data from one or more external data sources can be visually represented and placed within the virtual environment such that multiple data sources are displayed simultaneously in three dimensions.
In general, commands and control actions can be effected within the 3D virtual reality environment, in respect of the multiple data sources, by means of a number of different methods. One such method is by way of hand gestures, or other bodily movements, made by the user in respect of a selected function. However, problems may arise in the case where there are a number of different users of the system, some or all of which have different authorisations and permissions to access and/or manipulate the functions provided. When there are multiple people working in a close, collaborative environment, different people will be authorised for, and require, access to different functions and different security levels. Current methods of hand gesture detection are not able to distinguish between users and, therefore, cannot determine whether or not a user performing a particular hand gesture in respect of a selected function is permitted to access and/or manipulate that function. It would, therefore, be desirable to provide a method and apparatus for allowing an operator to access information and functions they need, whilst preventing the same operator from accessing functions or information for which they are not authorised, but for which another operator working in the same space is authorised and to which they require access.

Apparatus and method for effecting a control action in respect of system functions


The velocity of a photoreceptor belt is measured by sensing the passing of illuminated slits in the belt, as the belt moves in a process direction. Two linear position sensors are positioned so as to view the passing of the illuminated slits. The sensors are aligned in a staggered configuration so that there is an overlap region. The slits are positioned so that as one slit is moving off of a downstream sensor, a second slit is moving over the upstream sensor. The output from an illuminated sensor is alternately switched to the second sensor. The sensor outputs are differentiated to provide an output signal representing a belt velocity. The velocity is compared to said velocity in the belt drive system and error signals generated to compensate for detected changes in the belt velocity.

The present invention relates to a motion sensor for sensing the velocity of a moving web or belt and, more particular, to a motion sensor which uses a pair of linear position sensors to detect the passage of holes formed in the circumference of a photoreceptor belt to measure the velocity of the belt.
Highlight color and full color printers may use one or more imagers, such as Raster Output Scanners (ROS) or LED print bars, to expose the surface of a photoreceptor belt to form a plurality of superimposed color images. For the highlight color case, two exposures are made on the same exposure frame, or pitch, of the belt. Each exposure is developed with a characteristic color plus black. For a full color image, a single imager, in a multi-pass mode, or a plurality of imagers, in a single pass mode, form successive color images on successive exposure frames with a composite color image being developed and transferred to a copy sheet. Each color image must be registered with previously exposed and developed images with a high degree of accuracy. One source of registration error is velocity variations in the rotational velocity of the photoreceptor belt. A number of factors can contribute to changes in the photoreceptor velocity from a velocity at start of operation such as: variations in the speed of the belt drive motor; runout errors of the drive and tension idler roller; cleaning blade to photoreceptor surface interaction and belt thickness variations. These belt velocity variations cause the spacing between scan lines being formed by the imager on the photoreceptor surface to vary resulting in a visible "banding" effect in the output copies. Also, for a single pass color system, where three or four images are successively formed in a single revolution or pass of the photoreceptor, the leading edge of each exposure frame may vary from the precise registration requirements, It is therefore evident that there exists a need for some mechanism for monitoring the velocity of the belt in the process direction and for correcting for noted changes in the measured velocity.
There are several prior art references which disclose belt sensing and registration correction techniques. The most generally used mechanism is to mount an encoder in contact with a portion of the belt. The encoder provides a series of pulses per revolution, each pulse representative of an incremental distance of belt movement. The encoder outputs are sent to a drive servo control via a feedback loop; the servo control detects changes in the velocity of the belt and adjusts the motor drive of the belt. See, for example, U.S. Pat. No. 4,485,982 for an encoder used in a belt tracking system.
Encoders and related circuitry are expensive components; other less expensive techniques have been developed to produce signals representing the velocity of the belt or web. U.S. Pat. No. 4,837,636 discloses a system in which a belt is formed with a series of holes along one edge. The holes are illuminated and cause a CCD sensor array beneath the belt to be continually illuminated by the light source. Output signals from the sensor array are converted into clock signals which are used for controlling the belt drive motor velocity. U.S. Pat. No. 5,204,620 discloses a plurality of rectangular slits formed along the edge of the belt. The slits are illuminated and flux is incident on a segmented CCD position sensor on the other side of the belt. The sensor light output is sampled and the output during the sampling period is operated upon by a centroid processor to accurately determine the center of movement for each sampled intensity distribution. These prior art devices utilize CCD sensor arrays which, while less expensive than the encoder arrangements, are still a relatively expensive component.
The present invention is directed towards a mechanism for measuring velocity by using relatively inexpensive linear position sensors. In the embodiment which is used to disclose the sensor arrangement, narrow belt slits are formed in a belt in a cross-process direction and a light source is provided which illuminates the full width of the slits as well as the combined lengths of a pair of linear position sensors joined in a staggered arrangement. The light passing through the slits as they advance over the staggered sensor arrays provide output signals over time which represent the photoreceptor velocity. More particularly, the present invention relates to a printer having a photoreceptor belt moving in a process direction, said belt having a series of slits spaced from each other and extending in a row about the circumference of the belt with the length of said slits aligned in a direction generally perpendicular to said process direction, the combination of:
a sensor system for measuring the velocity of said belt, said sensor system including a pair of linear position sensors adjacent one surface of the belt, said sensors constructed in a staggered configuration to provide a continuous length longer than the length of either sensor while shorter than the slit spacing, said sensors aligned so that their lengths are generally parallel to the process direction, and an illumination source positioned on the other side of the belt and adapted to provide a band of illumination which illuminates the length of said slits and the combined length of said sensors, PA1 drive means for rotating said belt so as to move said slits across the combined length of said sensors to allow a continuous band of illumination from said light source to fall on said sensors, PA1 switching means for switching the operational state of said sensors as a function of the position of said slit and the output voltage of said sensors so that output signals are alternately generated by each sensor, and PA1 circuit means for differentiating said sensor output signals to produce a signal representing the velocity of the belt.

Photoreceptor belt motion sensor using linear position sensors