The present invention provides an apparatus and method for making an apparatus for sensing and/or characterizing a biopolymer translocating a nanopore. The apparatus of the present invention provides a first electrode, a first insulator, a second electrode, a optional insulator, a voltage source for applying a time varying potential difference between the electrodes, and a means of measuring the resulting current between the two electrodes. A method for making the apparatus is also disclosed.

Techniques for manipulating matter at the nanometer scale ("nanoscale") are important for many electronic, chemical and biological purposes (See Li et al., "Ion beam sculpting at nanometer length scales", Nature, 412: 166-169, 2001). Among such purposes are the desire to more quickly sequence biopolymers such as DNA. Nanopores, both naturally occurring and artificially fabricated, have recently attracted the interest to molecular biologists and biochemists for the purpose of DNA sequencing.
It has been demonstrated that a voltage gradient can drive a biopolymer such as single-stranded DNA (ssDNA) in an aqueous ionic solution through a naturally-occurring transsubstrate channel, or "nanopore," such as an α-hemolysin pore in a edgeid bilayer. (See Kasianowicz et al., "Characterization of individual polynucleotide molecules using a substrate channel", Proc. Natl. Acad. Sci. USA, 93: 13770-13773, 1996). The process in which the DNA molecule goes through the pore has been dubbed "translocation". During the translocation process, the extended biopolymer molecule blocks a substantial portion of the otherwise open nanopore channel. This blockage decreases the ionic electrical current flow occurring through the nanopore in the ionic solution. The passage of a single biopolymer molecule can therefore be monitored by recording the translocation duration and the decrease in current. Many such events occurring sequentially through a single nanopore provide data that can be plotted to yield useful information concerning the structure of the biopolymer molecule. For example, given uniformly controlled translocation conditions, the length of the individual biopolymer can be estimated from the translocation time.
One desire of scientists is that the individual monomers of the biopolymer strand might be identified via the characteristics of the blockage current, but this hope may be unrealized because of first-principle signal-to-noise limitations and because the naturally occurring nanopore is thick enough that several monomers of the biopolymer are present in the nanopore simultaneously.
More recent research has focused on fabricating artificial nanopores. Ion beam sculpting using a diffuse beam of low-energy argon ions has been used to fabricate nanopores in thin insulating substrates of materials such as silicon nitride (See Li et al., "Ion beam sculpting at nanometer length scales", Nature, 412: 166-169, 2001). Double-stranded DNA (dsDNA) has been passed through these artificial nanopores in a manner similar to that used to pass ssDNA through naturally occurring nanopores. Current blockage data obtained with dsDNA is reminiscent of ionic current blockages observed when ssDNA is translocated through the channel formed by α-hemolysin in a edgeid bilayer. The duration of these blockages is been on the millisecond scale and current reductions have been to 88% of the open-pore value. This is commensurate with translocation of a rod-like molecule whose cross-sectional area is 3-4 nm2 (See Li et al., "Ion beam sculpting at nanometer length scales", Nature, 412: 166-169, 2001). However, as is the case with single-stranded biopolymers passing through naturally occurring nanopores, first-principle signal-to-noise considerations make it difficult or impossible to obtain information on the individual monomers in the biopolymer.
A second approach has been suggested for detecting a biopolymer translocating a nanopore in a rigid substrate material such as Si3N4. This approach entails placing two tunneling electrodes at the periphery of one end of the nanopore and monitoring tunneling current from one electrode, across the biopolymer, to the other electrode. However, it is well known that the tunneling current has an exponential dependence upon the height and width of the quantum mechanical potential barrier to the tunneling process. This dependence implies an extreme sensitivity to the precise location in the nanopore of the translocating molecule. Both steric attributes and physical proximity to the tunneling electrode could cause changes in the magnitude of the tunneling current which would be far in excess of the innate differences expected between different monomers under ideal conditions. For this reason, it is difficult to expect this simple tunneling configuration to provide the specificity required to perform biopolymer sequencing.
Resonant tunneling effects have been employed in various semiconductor devices including diodes and transistors. For instance, U.S. Pat. No. 5,504,347, Javanovic, et al., discloses a lateral tunneling diode having gated electrodes aligned with a tunneling barrier. The band structures for a resonant tunneling diode are described wherein a quantum dot is situated between two conductors, with symmetrical quantum barriers on either side of the quantum dot. The resonant tunneling diode may be biased at a voltage level whereby an energy level in the quantum dot matches the conduction band energy in one of the conductors. In this situation the tunneling current between the two conductors versus applied voltage is at a local maximum. At some other bias voltage level, no energy level in the quantum dot matches the conduction band energy in either of the conductors and the current versus applied voltage is at a local minimum. The resonant tunneling diode structure can thus be used to sense the band structure of energy levels within the quantum dot via the method of applying different voltage biases and sensing the resulting current levels at each of the different voltage biases. The different applied voltage biases can form a continuous sweep of voltage levels, and the sensed resulting current levels can form a continuous sweep of current levels. The slope of the current versus voltage can in some cases be negative. Conceptually, it is also possible to inject a known current between the conductors and measure the resulting voltage, but this approach can fail if the characteristic current versus voltage has a negative slope region. For this reason, applying a known voltage bias and sensing the resultant current is usually the preferred method.
As discussed in Nonprovisional application Ser. No. 10/352,675 referenced above, a resonant tunneling electrode arrangement can be associated with a nanopore so as to sense the presence, and energy band properties of, a biopolymer molecule extending through the nanopore. This resonant tunneling electrode arrangement provides hope of not only sensing or characterizing a biopolymer, but of identifying the constituents of the polymer and meeting the goal of rapid and efficient DNA sequencing.
Thus there is a need for specific resonant tunneling electrode structures to be associated in such an arrangement with the nanopore in order to characterize biopolymers such as DNA, a method of using such resonant tunneling electrode structures to characterize biopolymers, and methods of building such resonant tunneling electrode structures. The references cited in this application infra and supra, are hereby incorporated in this application by reference. However, cited references or art are not admitted to be prior art to this application.

Nanopore with resonant tunneling electrodes


A depletion-mode MESFET is connected between an RF input terminal and ground. The gate is connected to a negative reference voltage via a bias resistor and to ground via a capacitor. A detector couples the input terminal to the gate and includes first and second series diodes and a second resistor connected from between the first and second diodes to ground. A coil is connected between the input terminal and an output terminal connected to a GaAs integrated circuit. A Schottky diode limiter is connected to the output terminal for limiting the voltage of both positive and negative polarities that leak to the output terminal from the transistor.

1. Field of the Invention
This invention relates to devices for protecting the input and output terminals of microwave circuits from excessive voltages. In particular, it relates to such devices having an FET switch selectively shunting the terminal to ground with a gate biasing circuit for controlling operation of the FET.
2. Description of the Prior Art
Devices for limiting the electrical energy reaching a device through one conductor or another, have existed for at least a generation. A common type of these is formed by placing a pair of silicon diodes back-to-back between the line to be protected and ground. When the voltage across the diodes rises above the breakdown threshold, the diodes conduct, shorting the excess power to ground. Some of the energy is reflected back out of the port of entry, some is absorbed in the diodes, and a small amount inevitably leaks through to the device to be protected.
If the incident high-power pulse has a fast rise time, energy can leak past the diodes before they have time to break down. This is termed spike leakage and, with silicon diodes, it can be enough to damage a GaAs MESFET. Since silicon diodes cannot be integrated into a gallium arsenide monolithic circuit, this type of protection would have to be externally connected to the chip to be protected. The additional bulk of the externally connected limiter would defeat the purpose for using GaAs MMICs in many applications such as phased-array radar and would increase the cost of the unit.
An alternate approach is to fabricate a gallium arsenide diode on the chip with the device to be protected. There are two types of semiconductor diodes. One consists of three different layers in which a thin undoped layer is sandwiched between a layer enriched with hole carriers and a layer enriched with electron carriers (the PIN diode). Also, a PN diode would work. This is the same as a PIN diode with an infinitely thin I layer. The other type consists of a film of metal evaporated directly onto a doped semiconductor. If the metal does not dissolve into the semiconductor, this forms a Schottky diode. In general the PIN diode offers a larger volume for absorbing electrical energy than does the Schottky diode. For this reason the PIN diode would be preferred; however, to achieve the speed necessary to function in the microwave regime, the carriers must be electrons and not holes. Therefore GaAs MMICs are always doped with elements that give rise to electrons as the dominant carrier species. To dope a portion of the chip with hole bearing elements in order to make a PIN structure would require additional processing steps and thus increase the cost of the product.
Shunt bipolar transistors are used to suppress transient signals from a power source in lower frequency applications, as is described in U.S. Pat. No. 4,849,845 issued to Schmitt for "Transient Suppressor". With this device, the base of the transistor is controlled by a sense and control circuit to turn the transistor switch on at a first voltage and off when the voltage reaches a level less than the first voltage. A resistor and optionally a diode are in series with the transistor. Such a system requires an elaborate control circuit, requires two transistor circuits for alternating current, and is not functional at microwave frequencies.
A more simple circuit is disclosed in U.S. Pat. No. 5,041,889 issued to Kriedt et al. for "Monolithically Integratable Transistor Circuit for Limiting Transient Positive High Voltages, such as ESD Pulses Caused by Electrostatic Discharges on Electric Conductors". This circuit uses a shunt bipolar transistor with the base biased by the parallel combination of capacitor and resistor connected to the input. A second capacitor connects the base to ground. Besides having the limitations of bipolar transistor operation, it is only functional on positive surges.
In U.S. Pat. No. 4,712,152 entitled "Semiconductor Integrated Circuit Device", Iio discloses the use of parallel NPN bipolar transistors, with bases and emitters connected to ground. The transistors have different breakdown voltages for accommodating power dissipation for different types of surges.
It is also known to use FETs in shunt between an RF input and ground. In U.S. Pat. No. 3,777,216 entitled "Avalanche Injection Input Protection Device", Armstrong discloses the use of an IGFET or MOSFET input shunt with a diode coupling the gate to ground. The IGFET is said to operate in an avalanche mode for one polarity of signal and in a conduction mode in the other polarity. This device requires avalanche breakdown of the drain-gate junction for operation and does not use active biasing.
Miyazawa et al., in U.S. Pat. No. 4,893,157 entitled "Semiconductor Device", disclose using two parallel shunt transistors separated in the signal path by a resistor. One or both of the transistors are IGFETs or MOSFETs. This device also requires the use of both N-type and P-type material, and does not use active biasing.
Sasaki discloses a similar device in U.S. Pat. No. 4,423,431 entitled "Semiconductor Integrated Circuit Device Providing a Protection Circuit". With this device, the gate of an IGFET or MOSFET is biased by a resistor in the input signal path and a capacitor connecting the input to the gate. A resistor, and optionally a parallel capacitor, couple the gate to ground. The silicon gate is said to be fabricated along with the internal circuit to be protected.
Yet another variation is disclosed by Arizumi in U.S. Pat. No. 4,527,213 entitled "Semiconductor Integrated Circuit Device with Circuits for Protecting an Input Section Against an External Surge". This variation requires a MOSFET shunt associated with the output side of each of two series input resistors. One MOSFET has a gate shorted to the drain which is grounded via a resistor. The second MOSFET is the same but without the resistor to ground. Other variations are also shown directly connecting a shunt IGFET gate to the source or leaving the drain unconnected.
Another similar device using two series shunt IGFETs is disclosed by Koike in U.S. Pat. No. 4,609,931 issued for "Input Protection MOS Semiconductor Device with Zener Breakdown Mechanism". As with the device of Sasaki, these devices all require an inline resistor and use of a special diffused region under a MOSFET.
Sitch, in U.S. Pat. No. 4,930,036, discloses an "Electrostatic Discharge Protection Circuit for an Integrated Circuit". This protection circuit uses a shunt MESFET on a signal line after a series resistor. The source and gate are separated by a second series resistor. A normally reversed-biased diode is connected between the FET gate and a low voltage source. The transistor conducts when a positive discharge is applied to the input terminal, and the diode conducts when a negative discharge is applied. This device has a gate-to-channel capacitance in the switch FET that must be charged through the in-line resistor to turn the FET on. This results in a delay in operation of the switch FET after a surge is applied. Further, the FET must be an enhancement-mode type to be off and to avoid degrading the functioning circuit when the input voltage is low.
In "High Power Control Components Using a New Monolithic FET Structure", IEEE 1989 Microwave and Millimeter-Wave Monolithic Circuits Symposium, pages 51-56, Shifrin et al. disclose three current-limiting devices that use a new monolithic switch FET design that reportedly overcomes the breakdown voltage limitation of a conventional switch FET to increase its power-handling capability. One involves a series connection of FET cells coupling the RF input to ground. The FETs are controlled by a common control signal balanced to make the FETs operate as concurrently as possible. Capacitors are applied between the FETs to compensate for parasitic capacitance. This circuit is reported as being effectively tested at 27 watts, with a similar four-cell device having a power control capability of 40 watts.
Shifrin et al. also disclose a set of FETs in parallel between various points on the input signal line and ground. There is no description of the control scheme, but it reportedly is used to control 40 watts. A third version is summarily discussed as involving a voltage-controlled attenuator with a voltage multiplier and operational amplifier providing voltage detection and feedback.
Specific integrated circuit structures to effect particular protection characteristics are disclosed in U.S. Pat. No. 4,807,080 issued to Clark for "Integrated Circuit Electrostatic Discharge Input Protection", apparently requiring the use of MOSFETs in a breakdown mode, and in U.S. Pat. No. 4,803,527 entitled "Semiconductor Integrated Circuit Device Having Semi-Insulator Substrate" and issued to Hatta et al. The device disclosed in this latter patent has a series resistor in the signal path and a depleted N layer under a floating gate or insulator, for use in conjunction with an associated electrostatic destruction protect circuit.
These FET devices are designed for operation in enhancement mode and most of them are designed to be used on digital or direct current terminals rather than microwave signal lines. There remains a need for a protection circuit using a shunt MESFET that is also operable in depletion mode, has a fast switch time in response to positive and negative power surges, and is able to give protection against large AC signals without significantly degrading the performance of the protected circuit. It is also desirable to have such a device that is self-biasing and is operable for both moderate and high overvoltage conditions, i.e., in ballast and breakdown modes. Further, such a circuit having a simple sense and control circuit is also desirable.


Anode foil, preferably aluminum anode foil, is etched using a process of treating the foil in an electrolyte bath composition comprising a sulfate and a halide, such as sodium chloride. The anode foil is etched in the electrolyte bath composition by passing a charge through the bath. The etched anode foil is suitable for use in an electrolytic capacitor.

1. Field of the Invention
The present invention relates generally to an etch electrolyte composition and method for etching anode foil to render it suitable for use in electrolytic capacitors, and to such electrolytic capacitors.
2. Related Art
Compact, high voltage capacitors are utilized as energy storage reservoirs in many applications, including implantable medical devices. These capacitors are required to have a high energy density since it is desirable to minimize the overall size of the implanted device. This is particularly true of an implantable cardioverter defibrillator (ICD), also referred to as an implantable defibrillator, since the high voltage capacitors used to deliver the defibrillation pulse can occupy as much as one third of the ICD volume.
Implantable cardioverter defibrillators, such as those disclosed in U.S. Pat. No. 5,131,388, incorporated herein by reference, typically use two electrolytic capacitors in series to achieve the desired high voltage for shock delivery. For example, an implantable cardioverter defibrillator may utilize two 350 to 400 volt electrolytic capacitors in series to achieve a voltage of 700 to 800 volts.
Electrolytic capacitors are used in ICDs because they have the most nearly ideal properties in terms of size and ability to withstand relatively high voltage. Conventionally, an electrolytic capacitor includes an etched aluminum foil anode, an aluminum foil or film cathode, and an interposed kraft paper or fabric gauze separator impregnated with a solvent-based liquid electrolyte. The electrolyte impregnated in the separator functions as the cathode in continuity with the cathode foil, while an oxide layer on the anode foil functions as the dielectric.
In ICDs, as in other applications where space is a critical design element, it is desirable to use capacitors with the greatest possible capacitance per unit volume. Since the capacitance of an electrolytic capacitor increases with the surface area of its electrodes, increasing the surface area of the aluminum anode foil results in increased capacitance per unit volume of the electrolytic capacitor. By electrolytically etching aluminum foils, an enlargement of a surface area of the foil will occur. As a result of this enlargement of the surface area, electrolytic capacitors, which are manufactured with the etched foils, can obtain a given capacity with a smaller volume than an electrolytic capacitor which utilizes a foil with an unetched surface.
In a conventional electrolytic etching process, surface area of the foil is increased by removing portions of the aluminum foil to create etch tunnels. While electrolytic capacitors having anodes and cathodes comprised of aluminum foil are most common, anode and cathode foils of other conventional valve metals such as titanium, tantalum, magnesium, niobium, zirconium and zinc are also used. Electrolytic etching process are illustrated in U.S. Pat. Nos. 4,213,835, 4,420,367, 4,474,657, 4,518,471 4,525,249, 4,427,506, and 5,901,032.
In conventional processes for etching aluminum foil, an electrolytic bath is used that contains a persulfate oxidizing agent, such as sodium persulfate. The etching is usually followed by treatment in nitric or hydrochloric acid. Sodium persulfate is a strong oxidizing agent which can control the etch process to initiate more tunnels per unit area, and can also prevent the etch tunnel walls from being completely passivated during etch. However, sodium persulfate is thermally and electrochemically unstable and tends to decompose to sodium sulfate over time at high solution temperature. Also, sodium persulfate, if not isolated from the cathode, tends to be unduly reduced at the cathode to form sodium sulfate. Above a certain concentration, sodium sulfate is believed to be detrimental to the foil capacitance. Thus, a high standard deviation in foil capacitance can occur if the persulfate and resulting sulfate levels are not tightly controlled. Accordingly, to maintain a high capacitance yield, sodium persulfate needs to be replenished in the etch solution, and the level of sodium sulfate must be controlled (i.e., removed from the etch solution).
It would be advantageous to utilize an etch process, particularly for a direct current (DC) etch process, which provides for a high voltage, high capacitance yield using agents that are more chemically stable than persulfate.

Process for producing high etch gains for electrolytic capacitor manufacturing


A scroll compressor is disclosed. In the scroll compressor of this invention, the involute fixed and orbiting scroll wraps engage with each other to form a plurality of variable compression chambers between them. In the compressor, at least one of the involute fixed and orbiting scroll wraps is formed at a middle section thereof to be thicker than the other sections. Therefore, it is possible for the fixed and orbiting scroll wraps to engage with each other without forming a gap at the central portion of the compression part, thus minimizing a leakage of compressed gas refrigerant during a gas refrigerant compressing process of the scroll compressor. The scroll compressor of this invention is thus improved in its gas refrigerant compression efficiency, and is reduced in its operational noises.

1. Field of the Invention
The present invention relates to scroll compressors and, more particularly, to a scroll compressor provided with a scroll wrap designed at a predetermined section to be different from the other sections in thickness, thus being improved in its gas refrigerant compression efficiency.
2. Description of the Prior Art
FIG. 1 is a sectional view of a conventional scroll compressor. FIG. 2 is a plan sectional view, showing the profile of the wraps of the fixed and orbiting scrolls of a conventional symmetric scroll compressor.
As shown in the drawings, the conventional symmetric scroll compressor has a main frame 20 and a sub-frame 25, which are set within a hermetic casing 1 at upper and lower positions. In such a conventional symmetric scroll compressor, a compression part 10, used for compressing gas refrigerant prior to discharging the compressed gas refrigerant, is set on the main frame 20 within the casing 1. A motor 30 is set within the space defined between the main frame 20 and the sub-frame 25, and is used for driving the compression part 10.
The above motor 30 comprises a stator 31 and a rotor 33, while the compression part 10 comprises a fixed scroll 11 and a orbiting scroll 15. The fixed and orbiting scrolls 11 and 15 have involute wraps 11a and 15a, with a phase difference of 180xc2x0 formed between the two wraps 11a and 15a, The two wraps 11a and 15a of the scrolls 11 and 15 engage with each other to form variable compression chambers C and Cxe2x80x2 between them.
When the stator 31 of the motor 30 is turned on, the rotor 33 is rotated along with the motor shaft 35, and so the orbiting scroll 15 is orbited relative to the fixed scroll 11.
When the orbiting scroll 15 is orbited relative to the fixed scroll 11 as described above, the variable compression chambers C and Cxe2x80x2 formed between the two wraps 11a and 15a of the scrolls 11 and 15 are gradually reduced in their volumes and are increased in their pressures in a direction toward the center of the compression part 10. Therefore, it is possible to compress the gas refrigerant introduced into the compression part 10 through an inlet port 16 and to discharge the compressed gas refrigerant from the compression part 10 into a refrigerant discharging pipe through an outlet port 19. Such a gas refrigerant compressing process of the conventional symmetric scroll compressor is shown in FIG. 4 in detail.
In order to minimize a loss during the gas refrigerant compressing process, it is necessary to prevent a leakage of compressed gas refrigerant. In the conventional symmetric scroll compressor, the compressed gas refrigerant may leak in a radial direction through axial gaps and leak in a tangential direction through radial gaps.
Such a tangential leakage of compressed gas refrigerant through radial gaps is caused by the gaps formed between the two wraps 11a and 15a at a plurality of tangential contact points P of the two scrolls 11 and 15.
FIG. 3 is a view, showing the design factors of a conventionally designed scroll of the conventional symmetric scroll compressor.
As shown in the drawing, the wrap 11a or 15a of each of the fixed and orbiting scrolls 11 and 15 of the conventional symmetric scroll compressor is shaped as an involute curve, comprising an inside involute and an outside involute designed to have a phase difference of xc2x1xcex1 between them. Each of the wraps 11a and 15a also has a constant thickness T.
That is, the thickness T of each wrap 11a or 15a is expressed as follows: T=L0xe2x88x92Li=a (xcex8+xcex1)xe2x88x92a (xcex8xe2x88x92xcex1)=2axcex1. This means that each wrap 11a or 15a has a constant thickness T from the first to the last.
However, such a conventional symmetric scroll compressor is problematic due to the constant thickness of the wraps 11a and 15a, That is, since the wraps 11a and 15a of the fixed and orbiting scrolls 11 and 15 of the conventional symmetric scroll compressor have such a constant thickness T as described above, a plurality of gaps are undesirably formed between the two wraps 11a and 15a at the tangential contact points P of the two scrolls 11 and 15 as shown in FIG. 2 due to a requirement of machining allowance and/or assembling allowance of the two wraps 11a and 15a. In addition, the size of such gaps is not uniform, and so the amounts of leaking gas refrigerant from the compression chambers C and Cxe2x80x2 of the compression part 10 are different from each other. This finally causes a reduction in the gas refrigerant compression efficiency and an increase in operational noises of such a conventional symmetric scroll compressor.
If the profile of each wrap 11a or 15a of the two scrolls 11 and 15 is shaped as an ideal involute curve, it is possible to allow the tangential contact points P of the two scroll wraps 11a and 15a to be completely free from such undesired gaps or to have only negligible gaps. In such a case, the symmetric scroll compressor accomplishes desired gas refrigerant compression efficiency. However, it is practically impossible to form such an ideal involute curve in the scroll wraps 11a and 15a due to a requirement of machining allowance and/or assembling allowance of the two wraps 11a and 15a, Therefore, a plurality of gaps having different sizes are formed at the tangential contact points P of the two scroll wraps 11a and 15a, thereby undesirably allowing a leakage of compressed gas refrigerant. This results in a reduction in the gas refrigerant compression efficiency and an increase in operational noises of the conventional symmetric scroll compressors.
FIG. 5 is a plan sectional view, showing the profile of the wraps of the fixed and orbiting scrolls of a conventional asymmetric scroll compressor.
As shown in the drawings, the conventional asymmetric scroll compressor is designed such that the involute terminal angle xcfx86exe2x80x2 of the fixed scroll wrap 15xe2x80x2 is larger than the involute terminal angle xcfx86e of the orbiting scroll wrap 11xe2x80x2 at an angle of 180xc2x0, with a plurality of variable compression chambers formed between the two scroll wraps 11xe2x80x2 and 15xe2x80x2. This asymmetric scroll compressor is preferably increased in the volume of its sucked gas refrigerant by at least 10% in comparison with the conventional symmetric scroll compressor without changing the inner diameters of the main and sub-frames.
In such scroll compressors, the term xe2x80x9cinvolute terminal angle of a scroll wrapxe2x80x9d means an angle formed between the initial end and the terminal end of the scroll wrap.
Different from the conventional symmetric scroll compressor, the conventional asymmetric scroll compressor has only one gas refrigerant suction part, and so the asymmetric scroll compressor does not have any gas refrigerant suction passage formed around the outer edge of the orbiting scroll. Therefore, this asymmetric scroll compressor is less likely to overheat the sucked gas refrigerant, and is improved in its volume efficiency in comparison with the symmetric scroll compressor. The asymmetric scroll compressor is thus allowed to gradually and smoothly suck gas refrigerant into its compression part, and is remarkably reduced in its pulse vibration in comparison with the symmetric scroll compressor when the compressed air refrigerant is discharged from the compressor.
However, the conventional asymmetric scroll compressor is problematic as follows. That is, the asymmetric scroll compressor uses the extended inside involute section xcfx86excx9cxcfx86exe2x80x2 of the fixed scroll wrap 11xe2x80x2 as a compression chamber different from the conventional symmetric scroll compressor which does not use such an inside involute section xcfx86excx9cxcfx86exe2x80x2 as the compression chamber. In addition, the fixed and orbiting scrolls of the asymmetric scroll compressor are designed such that the involute terminal angle xcfx86exe2x80x2 of the fixed scroll wrap 15xe2x80x2 is larger than that of the orbiting scroll wrap 11xe2x80x2 at an angle of 180xc2x0 different from the conventional symmetric scroll compressor. Therefore, the number of gaps allowing a leakage of compressed gas refrigerant is undesirably increased in the asymmetric scroll compressor.
FIG. 6 is a view, showing the profile of a scroll wrap of the conventional asymmetric scroll compressor having a dimensional error caused by both machining allowance and assembling allowance. When the orbiting scroll wrap 11xe2x80x2 is not shaped as an ideal involute curve, but has a dimensional error due to the machining allowance and the assembling allowance as shown in FIG. 6, it is fortunately possible to prevent a leakage of compressed gas refrigerant at the outermost contact point xcex40 (see FIG. 7) having a low pressure difference since the fixed scroll wrap 11xe2x80x2 comes into close contact with the orbiting scroll wrap 15xe2x80x2. However, it is almost impossible to prevent a formation of gaps at the inside contact points xcex41 and xcex42 (see FIG. 7), and so compressed gas refrigerant undesirably leaks through the gaps at the inside contact points xcex41 and xcex42. Since the pressure difference at the inside contact points xcex41 and xcex42 is so high that the leakage of the compressed gas refrigerant at said points xcex41 and xcex42 seriously influences the compression efficiency of the compressor, the asymmetric scroll compressor is undesirably reduced in its compression efficiency.
In addition, such a conventional asymmetric scroll compressor is designed such that the sealing structure of the compressor for preventing a radial leakage of compressed gas refrigerant is formed by biasing the orbiting scroll wrap 15xe2x80x2 toward the fixed scroll wrap 11xe2x80x2. However, this structure undesirably causes imbalance at the contact points xcex40, xcex41 and xcex42 due to dimensional error caused by the machining allowance and the assembling allowance, thus finally impacting the two scroll wraps 11xe2x80x2 and 15xe2x80x2 at the contact points between them and generating operational noises of the compressor.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a scroll compressor, of which at least one of fixed and orbiting scroll wraps is formed at a predetermined section thereof to be different from the other sections in thickness, and which is thus improved in its gas refrigerant compression efficiency and is reduced in its operational noises.
In order to accomplish the above object, the present invention provides a scroll compressor, comprising fixed and orbiting scrolls having involute wraps, the involute fixed and orbiting scroll wraps engaging with each other to form a plurality of variable compression chambers between them, wherein at least one of the involute fixed and orbiting scroll wraps is formed at a predetermined section thereof to be thicker than the other sections.
In an embodiment, the present invention provides a scroll compressor, comprising fixed and orbiting scrolls having involute wraps, the involute fixed and orbiting scroll wraps engaging with each other to form a plurality of variable compression chambers between them, wherein at least one of the involute fixed and orbiting scroll wraps is formed at a middle section thereof to be thicker than a terminal section.
In the above scroll compressor, the middle section of at least one of the involute fixed and orbiting scroll wraps extends from a point having an angle of xcfx86e-4xcfx80 to another point having an angle of xcfx86e-2xcfx80, with the involute terminal angle of the wrap formed from the initial end to the terminal end of the wrap being designated by xcfx86e.
In another embodiment, the present invention provides an asymmetric scroll compressor, comprising fixed and orbiting scrolls having involute wraps, with the involute terminal angle xcfx86exe2x80x2 of the fixed scroll wrap being larger than the involute terminal angle xcfx86e of the orbiting scroll wrap by a predetermined angle, thus forming an extension part xcfx86excx9cxcfx86exe2x80x2, wherein the involute fixed scroll wrap is offset at the inside surface of the extension part by a predetermined thickness, thus forming a gap between the fixed and orbiting scroll wraps at the extension part.
In a further embodiment, the present invention provides an asymmetric scroll compressor, comprising fixed and orbiting scrolls having involute wraps, with the involute terminal angle xcfx86exe2x80x2 of the fixed scroll wrap being larger than the involute terminal angle xcfx86e of the orbiting scroll wrap by a predetermined angle, thus forming an extension part xcfx86excx9cxcfx86exe2x80x2, wherein the orbiting scroll wrap is offset at its outside surface at a portion corresponding to the extension part of the fixed scroll wrap by a predetermined thickness, thus forming a gap between the fixed and orbiting scroll wraps at the extension part.

Scroll compressor having different wrap thicknesses


A terrain advisory system for an aircraft (A) comprises a processor (11) which compares terrain information, accessed from a memory (13) according to data from a navigation system (12), with dynamic flight parameters from a monitor (14) for the aircraft. The processor (11) also generates a trajectory signal and a pull-up signal to indicate, on a display (15), current aircraft trajectory relative to a line constructed from notional pull-up trajectories for the aircraft which avoid a predetermined clearance height without exceeding a predetermined acceleration acting on the aircraft during a pull-up maneuver.

This invention relates to an aircraft terrain advisory system, in which terrain information is compared with the dynamic flight parameters for that aircraft to indicate the current aircraft trajectory with respect to clearance heights for a terrain to be avoided by the aircraft without exceeding a predetermined acceleration of the aircraft during a pull up manoeuvre. The invention also relates to a method for indicating the current aircraft trajectory with respect to clearance heights for a terrain.
Consider an eye position above the ground, and the various lines of sight radiating from that position. Some of these lines of sight will intercept the ground or objects projecting from the ground, while others will not. The boundary between the lines of sight which do and do not intercept the ground is known as the visual horizon from that eye position
The operation of the aircraft terrain advisory system can be defined analogously. Consider the position of an aircraft above the ground, and consider the possible trajectories emanating from that point. For each of these trajectories it will be either possible or impossible to pull up from that point without exceeding a predetermined acceleration of the aircraft, given the dynamic flight parameters of that aircraft, such that the trajectory avoids hitting the ground. The region defined by trajectories from which pull up can be achieved is the region the current trajectory of the aircraft must remain in to ensure pull up is possible for a given acceleration of the aircraft. In practice the aircraft is required to avoid violating a clearance level above the ground and not just merely the ground.


A fiber optic coupler having a first lens element for inputting a point source of light from an optical cable and outputting a collimated light, optically coupled to one or more lens elements for receiving an input of collimated light from the first lens element and outputting a focused point of light into a fiber optic cable. The lens elements can be gradient index lens. The lens elements can be of varying sizes such that the first lens element can optically connect to one or more smaller lens elements to couple or split optical signals for two way communication on the optical cables.

1. Field of the Invention
This invention relates to fiber optic coupling and more particularly to multiple small lens elements coupled to a larger lens element for transferring collimated light at the interface for bilaterally combining or dividing light.
2. Description of the Related Art
In the past, transfers of light from one optical fiber to one or more others was accomplished by fusing two or more fibers together at an interface, or by reflecting a portion of a first beam in one direction and transmitting a second beam portion through a plate, or by reflecting a portion of a beam by a reflecting means partly in the beam path.

Fiber optic coupler combiner and process using same


An induction furnace includes an induction coil, an electrically non-conductive crucible having an inner diameter disposed within the induction coil, and an electrically conductive member disposed below the crucible and having an outer diameter which is further from the induction coil than is the inner diameter of the crucible. Due to the non-conductive nature of material disposed within the crucible at lower temperatures, the induction coil initially inductively heats the conductive member, which transfers heat to the material to melt a portion of the material. Once the material is susceptible to inductive heating (usually upon melting) the susceptible material is inductively heated by the induction coil. During the process, inductive heating of the material greatly increases as inductive heating of the conductive member greatly decreases due to low resistivity of the molten material and due to the molten material being closer to the coil than is the conductive member.

1. Technical Field
The invention relates to induction heating and an improved induction furnace. More particularly, the invention relates to an induction furnace for melting materials not susceptible to inductive heating at lower temperatures but which are susceptible to inductive heating at higher temperatures, especially upon melting. Specifically, the invention relates to an induction furnace having an electrically conductive susceptor disk which is inductively heated whereby heat is transferred from the disk to such materials to make them susceptible to inductive heating whereby the materials are then inductively heated to melt them.
2. Background Information
Induction furnaces are well known in the art. However, there are a variety of difficulties related to the inductive heating and melting of materials that are initially non-conductive or which have particle sizes sufficiently small so that they are not susceptible to inductive heating. Many prior art induction furnaces utilize a conductive crucible such that an induction coil couples with the crucible to transfer energy directly to the crucible to heat the crucible. Heat is then transferred from the crucible to the material to be melted via thermal conduction. In certain cases, the induction frequency and the thickness of the crucible wall may be selected so that a portion of the electromagnetic field from the coil allows coupling with any electrically conductive material inside the crucible to inductively heat the material directly. However, the direct inductive heating in such cases is quite limited. Because direct inductive heating of the material to be melted is far more effective than the method described above, a system to effect such direct inductive heating is highly desirable.
In addition, the conductive crucibles of the prior art may react with the material to be melted which causes unwanted impurities in the melt and thus requires the use of a non-reactive liner inside the crucible to prevent formation of such impurities. Typically, such liners are electrically non-conductive and thermally insulating. As a result, the transfer of heat from the crucible to the materials to be melted is greatly impeded, thus substantially increasing melting times. To expedite the transfer of heat from the crucible to the material to be melted, the crucible must be heated to undesirably high temperatures which can decrease the life of the crucible and liner.
In addition, there remains a need for an induction furnace capable of producing a continuous melt in an efficient manner, especially for semi-conductor materials. An efficient continuous melt induction furnace is particularly useful for continuous formation of semi-conductor crystals, which are highly valued in the production of computer chips.
U.S. Pat. No. 6,361,597 to Takase et al. teaches three embodiments of an induction furnace especially intended for melting semi-conductor materials and adapted to supply the molten material to a main crucible for pulling of semi-conductor crystals therefrom. Unlike the prior art discussed above, Takase et al. uses a quartz crucible which is electrically non-conductive along with a susceptor which is in the form of a carbon or graphite cylinder. In each of the three embodiments of Takase et al., the carbon or graphite cylinder susceptor is initially inductively heated by a high frequency coil whereby heat is transferred from the susceptor to raw material inside the crucible in order to begin the melting process. Once the raw material is melted, it is directly inductively heated by the high frequency coil in order to speed up the melting process. While this is a substantial improvement over the previously discussed prior art, the induction furnace of Takase et al. still leaves room for improvement, as discussed below.
The first embodiment of Takase et al. involves the use of a pipe extending upwardly into the quartz crucible whereby the pipe receives molten material from within the crucible by overflow and transmits it to a main crucible from which semi-conductor crystals are pulled. The carbon cylinder susceptor encircles the quartz crucible and is moveable in a vertical direction. Prior to melting the material in the crucible, the carbon cylinder is positioned so it covers the entire side wall of the crucible. Once some of the material is melted, the carbon cylinder is moved upwardly so that the molten material is inductively heated by the coil. Once the raw material is fully melted, additional raw material is added and the carbon cylinder is moved downwardly to cover the upper half of the side wall of the crucible so that the carbon cylinder is inductively heated and transfers heat therefrom to aid in melting the added raw material.
While the first embodiment of Takase et al. permits the susceptor to be substantially removed from the electromagnetic field of the induction coil so that it is not further inductively heated or so that the inductive heat is minimized therein, this process still has some disadvantages. One disadvantage to this configuration is the need to provide a mechanism to move the cylindrical susceptor upwardly and downwardly. Another disadvantage of the configuration is the need for a mechanism to monitor the melt in order to determine the proper time to move the susceptor away from the crucible side wall. Because direct inductive heating of the molten materials is more effective than inductive heating of the susceptor and subsequent transfer of heat from the susceptor to the material, any time that the susceptor is left in place after the molten material is susceptible to inductive heating, it prevents the more efficient direct inductive heating of the melt.
The second embodiment in Takase is similar to the first embodiment except that the pipe for transferring molten material from the quartz crucible to the main crucible does not extend upwardly into the quartz crucible. A mass of the initial raw material is disposed over the opening of the pipe and effectively serves as a stopper until the stopper portion is itself melted. In order to prevent the stopper from being melted too soon, the carbon cylinder initially only covers about two thirds of the upper portion of the side wall of the crucible so that heat transferred from the carbon cylinder is transmitted only to about the upper two thirds of the raw material. As the raw material is melted, the carbon cylinder is moved downward to cover the entire side wall of the crucible. Then the carbon cylinder is moved upwardly to cover the upper half of the side wall of the crucible whereby continued inductive heating of the carbon cylinder allows heat transfer from the carbon cylinder to raw material that is added to the melt. Induction heat is also generated in the melt at this point.
The second embodiment similarly suffers from the need for moving the cylindrical susceptor in a vertical fashion. The process must also be monitored in order to determine when to move the susceptor cylinder downwardly to maintain a reasonably high efficiency. Further, the susceptor interferes with the inductive heating of the molten material when positioned around the crucible while there is still unmelted raw material within the crucible.
In the third embodiment, Takase et al. provides a pipe which extends upwardly into the crucible as in the first embodiment to provide overflow of the molten material to the main crucible. In this embodiment, the susceptor has a crucible-like configuration whereby the susceptor cylindrical portion covers the sidewall of the quartz crucible and the bottom of the susceptor covers the lower surface of the quartz crucible. In this embodiment, the susceptor is not vertically moveable. Instead, the thickness of the susceptor sidewall and the frequency applied by the coil are selected so that the penetration depth of the induction current will extend beyond the susceptor into the quartz crucible so that it can inductively heat material inside. As with the prior embodiments, the susceptor is inductively heated and then transfers heat to the raw material to begin the melting process. Once the melting process has begun, inductive heating of the melt also occurs and the melt continues as a result of both inductive heating directly of the molten material as well as transferred heat from the inductively heated susceptor. In addition, the frequency applied to the coil is preferably initially at a relatively high frequency and then once the melting has begun is shifted to a relatively low frequency to better focus inductive heating of the molten portion of the material.
This third embodiment primarily suffers from the fact that the cylindrical susceptor remains in place and thus prevents inductive heating from being focused more effectively on the raw material within the crucible. Instead, the coil continues to inductively heat the carbon cylinder so that energy which might be applied to the material is absorbed by the carbon cylinder, which transfers heat to the raw material in the crucible in a far less effective manner.

Induction furnace for melting semi-conductor materials


A vibration actuator for effecting paging is provided in which a vibrating section of an electroacoustic transducer is driven using low frequencies to collide it against a fixed section, and the vibration generated from the collision is transferred as external vibration. The vibrating section of a coil and the fixed section are bonded via an elastic member provided therebetween. The vibration generated at the time of collision can be effectively increased by flexibly supporting a magnetic circuit composed of a magnet, a yoke, etc. and by driving the magnetic circuit with alternating current which has a polarity. To permit easier assembly and to prevent damage or deterioration in characteristics, it is preferable to provide an annular molded member, which has hook-like projections, around the magnetic circuit and to support the magnetic circuit by a rubber member attached to the hook-like projections.

1. Field of the Invention
The present invention relates to a vibration actuator for effecting paging which is incorporated in a portable telephone or the like to notify a user of the arrival of a received call not only by sound but also by vibration. More particularly, the present invention relates to the vibration actuator for paging suited for achieving a smaller, lighter design.
2. Description of the Related Art
Conventional vibration actuators for paging are also called vibration motors or vibration-generating actuators. They are required to be compact, thin and inexpensive, and also to be capable of generating vibration at low power consumption. They are intended, however, to generate only vibration. Therefore, they cannot be used for making a voice call or issuing conversational voice. Hence, at least two component units are necessary for obtaining the information on incoming calls and for generating voice signals. Further, the pager vibrating motors which are extensively used consume much starting power for rotating a relatively large mass. They are also disadvantageous in that they have many components because of the rotating design, and provide unsatisfactory reliability or accuracy control. The conventional pager vibrating motors have a further disadvantage, namely, they include current switching brushes because they use direct current, so that they may generate large electromagnetic noises or incur a malfunction at the time of rotation, and they also have a limitation in accomplishing a smaller and flatter design.
FIG. 1 shows a pager vibrating motor which has been most commonly used hitherto. A counterweight 3 is rotated via a shaft 2 driven by a driving motor 1 composed of a cylindrical coreless rotor. The counterweight swings to generate vibration. Naturally, the pager vibrating motor is not capable of generating sound other than the vibration. The driving motor 1 is constituted by a permanent magnet having a curved surface and the cylindrical coreless rotor; and a plurality of magnetic poles to provide rotational driving force. This places restrictions on accuracy control and manufacturing cost in achieving a smaller diameter of the driving motor 1.
FIG. 2 shows the cylindrical pager vibrating motor in a vibrating state. As the driving motor 1 runs, the counterweight 3 swings around a rotational center 4. The vibration is generated in many directions, and therefore, the vibration in a particular direction may not be effectively transferred outside, depending on how the vibration motor for a pager is fixed. Further, a driving force is mandatory because the swinging moment is proportional to the square of the rotational speed of the driving motor 1, thus limiting the efforts in saving power.
FIG. 3 is a perspective view illustrative of the interior of a flat type pager vibrating motor 5 constructed by a conventional flat coreless rotor. A rotary shaft 8 is provided with a disc-shaped winding coil 6 with an eccentric center of gravity to generate a rotational driving force between the winding coil 6 and a sheet-like permanent magnet 7. Driving current is supplied through a brush 9. Unlike the cylindrical motor, the pager vibrating motor 5 makes use of the winding coil 6 with the eccentric center of gravity in place of the counterweight. The winding coil produces vibration when it revolves. Obviously, this pager vibrating motor 5 also cannot be used for generating the voice.
FIG. 4 shows the most effective vibration of the flat type pager vibrating motor 5. The rotations in the axial direction relative to a vibration central axis 10 are indicated by reference numerals 5, 11 and 12 assigned to the main body of the pager vibrating motor 5. There are thickness vibration in the axial direction and diametral vibration at right angles to the axis 10. Frequently, however, the vibrations may hardly contribute to the vibration to be transferred outside, depending on the way the flat type pager vibrating motor 5 is fixed. This means that the driving current applied to the winding coil 6 is not effectively used as the energy for transferring the vibration outside.
Thus, the conventional pager vibrating actuators have not been able to generate sound and voice although they are able to generate vibration. Furthermore, the conventional pager vibrating actuators have not necessarily been able to reduce the required starting power, they have hardly permitted a smaller overall size, and some of them have been prone to rotational malfunction, producing large electromagnetic noises.


Pipeline flow optimization systems, software, and methods that emulate transient optimization are disclosed. A pipeline flow optimization system includes an upset condition handler that is adapted to provide a multivariable controller with pipeline flow adjustments to handle one or more upset conditions. The optimization system may be used with fluid pipeline systems, including gas pipeline systems and liquid pipeline systems. Systems, software, and methods according to embodiments of the invention may further include linepack transition handling capabilities and administrative tools.

1. Field of the Invention
The invention relates to software and methods for fluid pipeline optimization and control, and more specifically, to optimization and control software and methods that can optimize for transient conditions within the fluid pipeline.
2. Description of Related Art
Fluid pipeline systems, such as gas transmission pipelines, operate at certain pressures and with certain flow rates in order to deliver fluid, for example, natural gas, to its destination. In the case of a gas pipeline, compressors along the pipeline maintain the pressures necessary to move the gas. In the case of a liquid pipeline, pumps move the liquid along the pipeline.
FIG. 1 is a diagram showing a typical gas pipeline system. Generally, referring to FIG. 1, a typical gas pipeline system may include multiple relay compressor stations with multiple points of supply and deliveries. For example, FIG. 1 shows a pipeline system having 6 compressor stations. Each individual station is controlled by control logic that, among other things, operates compressors and prevents a station from exceeding its maximum allowable operating pressures. The pipeline operator, through a supervisory control and data acquisition (SCADA) system, gives each individual compressor station's control logic its own target setpoints for suction pressure, discharge pressure and flow. The station's control logic seeks to maintain these target setpoints by starting and stopping compressors, as necessary. Additionally, as noted above, the control logic protects the station from exceeding its maximum allowable operating pressures and maintains it within safe operating parameters. However, the station control logic controls an individual station. Hence, it functions independent of the other stations in the system.
FIG. 2 is a diagram showing a pipeline flow control system that may be utilized to control the pipeline system of FIG. 1. Generally, referring to FIG. 2, a pipeline flow control system may include steady-state Optimization Software that calculates optimal target setpoints for the pipeline operator to manually send to the individual stations' control logic. Further, as FIG. 2 shows, the system may also include a multivariable control system ("Controller Software") operating in conjunction with the optimization software. The multivariable controller software may include a set of controllers that attempts to drive a set of station discharge pressures to equal a set of discharge pressure targets calculated by the optimization software, and there may be one controller for each compressor station that is operating under multivariable control. Each controller attempts to manipulate the suction pressure of the compressor station it controls in order to drive the discharge pressure of the next upstream station toward its optimal discharge pressure target.
However, fluid pipelines are dynamic systems, and the control systems described with reference to FIG. 1 and FIG. 2 may not anticipate or take into account certain transient (i.e. non-steady state) conditions. Additionally, because each controller in the system of FIG. 2 typically controls its station in light of operating conditions at that station and the next upstream station only, the controller software is controlling individual stations on the pipeline, which are all interconnected, based on data gleaned from only a portion of the stations in the system. Hence, the controller software may not effectively control all stations on the pipeline system in light of transient conditions affecting the entire pipeline system or other portions of the pipeline system beyond the control of an individual controller. Accordingly, the controller software may, among other things, increase the cost of transporting fluid through the pipeline.
Further, the system shown in FIG. 2 utilizes a single set of tune parameters to handle all transient conditions but that are aimed at only controlling the setpoints of the immediate upstream compressor station. However, certain transient conditions may occur in the pipeline system that can not be efficiently or effectively managed by only controlling the setpoints of the immediate upstream compressor station. In such transient conditions, the controller software's single set of tune parameters does not provide the capability to adjust station operating parameters to effectively or timely handle the transient conditions. Hence, in this case, the stations' control logic over-rides the multivariable controller software and controls corresponding individual compressor station targets to near maximum operating pressures. Generally, this leads to an imbalance in the system, which usually results in not being able to take the full contracted supplies into the transmission system.
Additionally, the control system of FIG. 2 is not able to identify or transition to a new optimal solution when conditions change (e.g. supplies or deliveries of the transmission system) that require a change to the optimal compressor configuration. A particular problem encountered was when to start additional compressors when required for an optimal fuel-efficient system. Starting the additional compressors too early wastes fuel. On the other hand, starting the additional compressors too late may cause a transient condition that is beyond the capability of the controller software to control, resulting in station control logic overriding the controller software.

Pipeline flow control optimization software methods


A sheet take-out apparatus has a stacker that houses sheets in the stacked state, a take-out roller for taking out sheets by rotating in contact with a sheet at one end in the stacking direction of housed sheets, and sensors for detecting a contact pressure of the take-out roller to sheets. A controller monitors a contact pressure of the take-out roller to sheets, energizes a motor so as to adjust a contact pressure to a proper value and moves the take-out roller in the stacking direction.

1. Field of the Invention
The present invention relates to a take-out apparatus to take out a sheet one by one separated from sheets in the stacked state.
2. Description of the Related Art
So far, for example, a postal matter take-out apparatus (hereinafter, simply referred to as a take-out apparatus) to take out one by one from postal matters in the stacked state and feed to a processing portion at the latter stage is known as a take-out apparatus.
This take-out apparatus has a stacker to house plural postal matters in the stacked state in the erected position. There is a take-out roller provided to pressure push postal matters out of plural postal matters stacked in the stacker at one end in the stacked direction. This apparatus has a separation portion to receive the postal matters taken out by the take-out roller and pass through a nip portion formed between a feed roller and separate postal matters taken out in the overlapped state. Further, the apparatus has a pull out portion to receive the front end of a postal matter passing through the nip portion of the separation portion and pulling it out and feed to the processing portion at the latter stage.
The take-out roller rotates in a prescribed direction and takes out postal matters at one end in the stacked direction on a conveying path. The take-out roller is arranged to press fit to postal matters at one end in the stacking direction using a spring/a counter balance.
The separation portion has a feed roller to feed postal matters taken out by the take-out roller on the conveying path along it and a separation roller in contact with the feed roller on the conveying path. The separation roller generates a torque in the direction reverse to the conveying direction and separates a second and subsequent postal matters from postal matters at one end of the stacking direction.
The pull out portion has a pull out roller pair that rotates at a peripheral velocity faster than at least the feed roller of the separation portion, and pulls out a postal matter clamped in the nip portion between the feed roller and the separation roller of the separation portion. Thus, the velocity of the feed roller of the separation portion and that of the pull out roller are differentiated, a gap between postal matters being conveyed on the conveying path is kept at a constant level.
However, in a conventional take-out apparatus described above, the take-out roller is pressed against postal matters at one end in the stacking direction using a spring or a counterbalance and therefore, a contact pressure of the take-out roller to postal matters at one end in the stack direction changes depending on difference in volume, elasticity, weight, etc. of postal matters stacked at one end of the stacking direction and the contact pressure could not be stabilized. Therefore, in the case of conventional apparatus, all of stacked postal matters could not take out under the same conditions and various problems were taken place. That is, there were such problems that if the contact pressure of the take-out roller was lower than a proper value, postal matters could not taken out and if the contact pressure was higher than a proper value, two sheets were taken out at a time in many cases.
Further, in the case of the above-mentioned conventional taken out apparatus, postal matters thicker or thinner than a defined thickness were processed jointly with postal matters in defined thickness and such postal matters in different materials as paper, vinyl sheets, etc. Therefore, the separation torque in the separation portion was set at a relatively large torque. That is, in order to separate all postal matters in different state one by one in the separation portion, it was necessary to increase the separation efficiency by setting a torque in the reverse direction by the separation roller relatively large. However, when the torque of the separation roller is increased, there was such a problem that postal matters were contaminated or damaged by a friction between the surfaces of postal matters and the separation roller when postal matters are pulled out by the pull out pair.
Furthermore, in the case of the above-mentioned conventional take-out apparatus, plural postal matters are taken out by the take out roller and the velocity of the feed roller of the separation portion and the pull out roller is made difference so as to form a certain gap between postal matters. However, there were many cases wherein a gap could not stabilize by jamming or slip of postal matters.


A sensing amplifier for a memory cell comprises a selection stage that outputs one of a reference current and a memory cell current during a first period and the other of the reference current and the memory cell current during a second period. The first period and the second period are non-overlapping. An input stage generates a first current based on the one of the reference current and the memory cell current during the first period and generates a second current based on the other of the reference current and the memory cell current during the second period. A sensing stage senses a first value based on the first current and stores the first value during the first period, senses a second value based on the second current during the second period and compares the first value to the second value.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a memory integrated circuit (IC) 10 is shown. The memory IC 10 comprises a memory array 12, a decoder 14, and a state sensing circuit 16. The memory array 12 includes an array of memory cells 15. The decoder 14 selects one of the memory cells 15 of the memory array 12. The state sensing circuit 16 senses a state of the selected memory cell 15.
Specifically, the state sensing circuit 16 comprises a voltage source 17 that applies a voltage difference across first and second bit lines (not shown) that are connected to the selected memory cell. The state sensing circuit 16 senses current that flows through the selected memory cell (Icell). The value of Icell changes depending on the state of the selected memory cell. Typically, the state sensing circuit 16 utilizes a sense amplifier 18 that senses a voltage drop Vcell generated by Icell. The sense amplifier 18 compares Vcell to a reference voltage Vref. For binary memory cells, the sense amplifier 18 determines the state of the selected memory cell based on whether Vcell is greater or less than Vref.
Referring now to FIG. 2, a typical sense amplifier 50 is shown. The sense amplifier 50 uses a latch-type structure comprising two mirrored circuits, each comprising a differential pair of transistors. Specifically, a first differential pair of transistors Q1 and Q2 is cross-coupled to a second differential pair of transistors Q3 and Q4 as shown. Vcell and Vref are input to transistors Q3 and Q4, respectively. The transistors Q3 and Q4 represent two inputs or two input paths of the sense amplifier 50. One input or input path (e.g., Q3) is used for sensing Vcell while another input or input path (e.g., Q4) is used for sensing Vref.
The sense amplifier 50 compares Vcell to Vref and generates outputs V1 and V2 that indicate the state of the selected memory cell. For example, V1 may be positive and V2 may be negative indicating that the state of the selected memory cell is a binary 1 when Vcell>Vref. Conversely, V1 may be negative and V2 may be positive indicating that the state of the selected memory cell is a binary 0 when Vcell<Vref.


A flat panel x-ray imager exhibiting reduced ghosting effects and overvoltage protection by appropriate leakage current characteristics of the thin-film transistor array. A top electrode of a suitable material is directly on a non-insulating organic layer. The organic layer is directly on an amorphous selenium-based charge generator layer allowing charge transport across the layer, thereby reducing ghosting. The thin-film transistors have leakage current that rises relatively slowly with voltage across the transistor within a range that matches exposure through an object being imaged but rises at a sufficiently higher rate within a higher range to provide protection even when a corresponding region of the charge generator layer receives greater amounts of x-rays.

Flat panel x-ray imaging devices that use charge generator materials such as doped amorphous selenium charge generator layers and directly convert x-rays to electrical charges and thus generate electrical signal related to local x-ray exposure, have been developed in recent years. See, for example U.S. Pat. No. 5,319,206, and Yorker J., Jeromin L., Lee D., Palecki E., Golden K., and Jing Z., "Characterization of a full field mammography detector based on direct x-ray conversion in selenium," Proc. SPIE 4682, 21–29 (2002). Commercial versions for general radiography and for mammography have been available for more than a year in this country from Hologic, Inc. of Bedford, Mass. ("Hologic") and Direct Radiography Corporation of Newark, Del. ("DRC"). The DRC imager is used in mammography systems that have been available for more than a year in this country from Lorad Corporation of Danbury, Conn. ("Lorad"). In such direct conversion panels, the charge generator material directly converts x-rays into pairs of electrons and holes and, under an applied electrical field, the holes and electrons migrate to respective electrodes with very little lateral loss to neighboring pixels. Direct conversion is believed to offer better spatial resolution and other advantages over indirect conversion panels, in which x-rays cause scintillation in a material such as cesium iodide and the resulting light energy is detected.
The structure of a direct conversion flat panel imager of the type referred to above is illustrated in principle but not to scale in FIG. 1. It comprises a top electrode 100, a charge barrier layer 102 (typically made of Parylene) separating the top electrode from an amorphous selenium-based charge generator layer 104, an electron blocking layer 106 patterned into a two-dimensional pixel array, a charge collection electrode 108 that also is patterned into a pixel array, a thin-film transistor ("TFT") array comprising respective transistors 110 coupled to the charge collection electrode and to respective signal storage capacitors 112, a substrate 114 typically made of glass, a gate pulse line 116 that enables (turns ON) the transistors to deliver to charge amplifiers 118 the charges collected at the respective storage capacitors, an a programmable high voltage power supply 120. The illustrated equivalent capacitor circuit for a pixel comprises a capacitor 122 representing capacitance across the charge barrier layer, a capacitor 124 representing capacitance across the charge generator layer, and a capacitor 126 representing capacitance of the charge storage capacitor for the pixel. One of the functions of the charge barrier layer is protection of the thin-film transistors, which can suffer breakdown damage if the charge stored in the charge storage capacitors becomes too high, e.g. when a capacitor stores charges generated at a region of the charge generating layer that receives x-rays that have not been attenuated by the object being imaged. For example, in mammography the corners of the flat panel imager typically are outside the breast outline and can receive much more radiation than the part of the imager under the breast. The charge barrier layer protects such transistors by collecting charges that gradually reduce the electrical field in the appropriate portions of the charge generator layer, and thus reduce the amount of charge that would otherwise collect at the pertinent charge collection capacitors.
The charge barrier layer thus contributes to meeting one of the challenges in flat panel detectors, namely, breakdown protection of the thin-film transistors. Another challenge is ghosting (remnants of one or more previous images) due to the time it takes to dissipate charges collected in the imager from previous x-ray exposures. Various techniques have been developed and used commercially to remove or at least reduce ghosting to an acceptable level. They include charge erasing by exposure to visible light between x-ray exposures and various ways to manipulate the bias potential of electrodes between x-ray exposures. The time needed to attend to ghosting makes it difficult to take images in rapid succession, such as for fluoroscopy or tomosynthesis.
It has been reported that it would be impractical to use a direct conversion panel without a charge barrier layer. Thus, a 1998 paper by well-known researchers in the field of direct conversion panels states that direct metallization of a selenium based detector in theory would allow for rapid imaging but concludes based on experimental data that this gives non-reproducible and unstable results. Polischuk B., Shukri Z., Legros A., and Rougheout H., "Selenium direct converter structure for static and dynamic x-ray detection in medical imaging applications," SPIE Conference on Physics of Medical Imaging, San Diego, Calif., February 1998, SPIE Vol. 3336, pp. 494–504, states that "In order to develop a selenium based x-ray detector which could operate in real time, i.e. 30 frames per second, a direct metallized selenium structure would be required. It is well established in solid-state theory that metallic electrodes deposited directly onto the free surface of semiconductor layers can behave as Schottky contacts." The paper then states that "most metals with lower work functions [than selenium] should have built-in potential barriers which could minimize the injection of excess charge from the metal electrode," but the paper reports that tests showed that "sample-to-sample variability and contact instability were common observations on these samples," and that "It was therefore concluded that any x-ray detector which relied only on the Schottky contact to limit dark currents would provide non-reproducible and unstable results." The paper proposes the solution of including a blocking layer between the top electrode and the selenium, and states that "The role of the top blocking layer is to limit the injection of positive charge from the metallic electrode, but allow any x-ray-generated electron to move unimpeded from the selenium layer to the metallic contact." The authors of the article are from Noranda Advanced Materials of Quebec, Canada, an entity that is believed to have been, at the time, a major developer of flat panel selenium-based x-ray imagers, in addition to DRC.
A number of earlier proposals have dealt with the issue of high voltage protection in flat panel detectors. U.S. Pat. No. 6,353,229, granted to the three authors of the 1998 paper and two other inventors, refers to several such proposals. One is cited at column 1, lines 24–39 and is reported to involve a special dual-gate TFT (thin-film transistor) structure that forms a back channel in the TFT structure if the pixel voltage exceeds a certain potential. See, Zhao W., Law J., Waechner D., Huang Z., and Rowlands J., "Digital radiology using active matrix readout of amorphous selenium detectors with high voltage protection," 1998 Med Phys 25 (4), pp. 539–549. Another is discussed at column 1, lines 46–57 (U.S. Pat. No. 5,198,673) and is said to involve the use of a second two-terminal protection device resident at each pixel location. The patent also refers, in the section entitled "Description of Prior Art," to a number of other items of prior art: (1) PCT International Application WO 96/22616 published Jul. 25, 1996; (2) Lee D., Cheung L. K., and Jeromin L., "A new digital detector for projection radiography," 1995, SPE Vol. 2432, pp. 237–249; (3) U.S. Pat. Nos. 5,598,004 and 5,396,072 (stating that "no mention is made [in those patents] of the high voltage protection of the TFT array"); (4) U.S. Pat. No. 5,528,043 (stating that the patent "does not mention whether high voltage protection of the circuit from the selenium bias is achieved"); (5) U.S. Pat. No. 5,436,101 (stating that "there is no mention of any high voltage protection of any element on the substrate"); and (6) Canadian patent application 2,184,667 published Mar. 4, 1998 and corresponding EP 0 826 983 published the same day (stating that "no indication of how this structure could be used for high voltage protection is given").
U.S. Pat. No. 6,353,229 proposes to achieve high voltage protection "by setting the high voltage biasing electrode to a negative potential and the TFT "off" gate voltage to a predetermined negative value such that the TFT is essentially non-conductive." The patent recognizes that "there will always be some TFT leakage" but states that "the negative 'off' voltage may be adjusted so as to minimize the same and render the TFT essentially non-conductive." See column 2, lines 49–61.
Earlier papers and patents are believed to be consistent with the patents and papers cited above. See U.S. Pat. Nos. 5,132,541, 5,184,018, 5,396,072, and 5,942,756, and Zhao W. and Rowlands J. A., "A large area solid-state detector for radiology using amorphous selenium," SPIE Medical Imaging, Vol. 1. 1651, pp. 134–143, 1992. A more recent U.S. Pat. No. 6,469,312, illustrates in FIG. 2 an electrode 2 on a recording side photoconductive layer 3 containing amorphous selenium as a main component, but has a wavelength conversion layer 1 in front of an electrode layer 2, which serves as a scintillator so that the amorphous selenium later 3 would serve as a light detector.
Each of the patents and papers cited above is hereby incorporated by reference in this patent specification as though fully set forth herein.

Amorphous selenium flat panel x-ray imager for tomosynthesis and static imaging


A sound absorbing structure for an automobile having a seating portion, an upper surface of which serves as a passenger seating surface in the cabin, the structure includes an interior base material provided on a cabin side of a body panel; the interior base material forming a side face when seen from a passenger seated on the seating portion; the interior base material having a recessed portion formed in the cabin side of the interior base material; the recessed portion formed on an upper side of the seating surface; and a sound absorbing material buried in the recessed portion. An automobile sun visor includes a plate-form core material; an air-permeable cushioning material covering a surface of the core material; and the plate-form core material having a large number of air holes penetrating in a thickness direction formed in a dispersed manner.

(1) Field of the Invention
The present invention relates to a sun visor for an automobile having a sound absorbing structure, and a sound absorbing structure for an automobile in which an interior base material is provided on the cabin side of a body panel.
(2) Description of Related Art
Typically, the body of an automobile is constituted by a plurality of panels which are press-molded and welded to form the outer shape of the automobile and various interior spaces such as a passenger cabin, an engine compartment, a luggage compartment, and so on. The body is basically formed by partially welding a panel on the vehicle exterior, known as an outer panel, and a panel on the vehicle interior, known as an inner panel, such that a space remains therebetween. The formed body is submerged in a rustproofing liquid to form an undercoating, subjected to drying processing in a furnace, and then finished by applying a coating thereto a plurality of times. Various functional components are then attached to the body, and various interior materials are carpeted so as to cover the inner panel on the cabin interior side of the body. The interior material is typically formed by covering a thick base material made of a thermoplastic resin having excellent thermal moldability with a designed surface material. An interior base material is molded into a three-dimensional shape corresponding to the shape of the inner panel in a carpeting position, carpeted onto the inner panel, and engaged with the inner panel using an engagement tool such as a resin clip.
Further, a light-shielding sun visor is installed in the passenger cabin of the automobile for preventing glare on the eyes of a passenger caused by direct sunlight or the lights of an opposing vehicle. In this type of sun visor, a plate-form core material is covered with a surface material such as fabric or leather to enhance the design quality thereof. An L-shaped spindle is fixed in a position near the front window on the ceiling of the automobile cabin, and one side edge of the sun visor is inserted into the spindle so as to be supported rotatably. The passenger sets the sun visor in a horizontal state when not in use so that the sun visor is stored in a storage position parallel with the ceiling of the vehicle. To block sunlight or the like coming from the direction of the windshield, the sun visor can be rotated about a horizontal central axis in the direction of the front window, and to block sunlight or the like coming from the side window, the sun visor can be rotated further about a vertical central axis in the direction of the side window. By having the passenger rotate the sun visor manually while holding a part of the sun visor by hand in this manner, the sun visor can be positioned freely and used in the position in which it is disposed.
The sun visor described above must possess a certain degree of rigidity to ensure that it does not bend or become deformed when the passenger applies force thereto in order to perform a rotation operation. Accordingly, a sun visor main body (sun visor core) employs a plate-form core material having a constant rigidity such as a wooden board, a thermoplastic resin molded body, or a resin particle foam-molded body. Further, the core material is covered in a surface material made of various types of fabric or leather to provide the sun visor with a design quality suited to the interior material of the passenger cabin.
FIG. 7 shows a cross-section of an automobile sun visor 900 disclosed in Japanese Utility Model Publication H6-845. In this sun visor 900, a frame 904 is formed in advance by bending a metal wire made of steel wire or the like into the desired outer peripheral shape of the sun visor. A plate-form core material 902 made of comparatively rigid cardboard or the like is fitted into the frame 904 and fixed with tape, for example. The integrally-formed frame and reinforcing plate are sandwiched on both sides by a padding material 906 made of slab urethane or the like and serving as a cushioning layer. A surface layer 908 knitted into a bag form having an interior space corresponding to the core material 902 is provided on the outside of the padding material 906.
As described above, a space is provided between the outer panel and inner panel of the body of the automobile, and hence many locations are formed to be hollow. Since these locations are basically cavities, various noises such as road noise, engine noise, and wind roar generated as the automobile travels along a road propagate through the cavities and leak through the inner panel into the passenger cabin in which the passengers are seated, or reach the passenger cabin through the luggage compartment, engine compartment, and so on adjacent to the passenger cabin, thereby impeding passenger comfort. To make the passenger cabin quieter, various proposals have been made for securing sound absorbency and sound insulation in the carpeting material for carpeting the cabin interior side.
In Japanese Unexamined Patent Application Publication H6-286530, a pillar garnish made of a synthetic resin and having a hollow portion formed into a surface-shape is used, and sound insulation is achieved by means of the hollow portion, which is a completely closed space.
In Japanese Examined Patent Application Publication 2000-516175, sound insulation is achieved by fixing a noise-reducing assembly package comprising a hard layer having minute pores to a flat, surface-shaped body part.
Japanese Unexamined Patent Application Publication 2004-90829 describes a sun visor comprising a plate-form core material having a constant rigidity and a constant air permeability, and a surface material having a constant air permeability which is disposed so as to cover the surface of the plate-form core material.
With the technique of Japanese Utility Model Publication H6-845, infiltrating sound such as road noise infiltrating the cabin interior is reflected by the sun visor and enters the ears of the passenger, and hence it is assumed that infiltrating sound which infiltrates the cabin interior is not reduced.
With the technique of Japanese Unexamined Patent Application Publication H6-286530, infiltrating sound is reflected on the cabin side surface of the pillar garnish and enters the ears of the passenger, and hence it is assumed that infiltrating sound which infiltrates the cabin interior is not reduced.
In the technique of Japanese Examined Patent Application Publication 2000-516175, the noise-reducing assembly package must be fixed to the surface-shaped body part, and therefore, in order to achieve a favorable design quality, the assembly package must be fixed to the entire surface of the cabin interior. Therefore, the material cost of the assembly package is high, and the operation to install the assembly package takes time, leading to an increase in the cost of the operation. Accordingly, there is room for improvement in terms of cost reduction.
With the technique of Japanese Unexamined Patent Application Publication 2004-90829, infiltrating sound entering the ears of the passenger is reduced to a certain extent. However, it is desirable to reduce the infiltrating sound which enters the ears of the passenger even further.
Note that the technique described in Japanese Unexamined Patent Application Publication 2002-356184 refers to a working vehicle rather than an automobile, and therefore cannot be applied to the present invention. As shown in FIG. 4 of Japanese Unexamined Patent Application Publication 2002-356184, in this document a sound absorbing sheet is formed by laying a sound absorbing material on the underside of a step mat having a large number of holes punched therein, and a silencing effect is obtained by carpeting or affixing the sound absorbing sheet onto parts of the cabin interior excluding the window portions. However, since the sound absorbing sheet is provided on all surfaces of the cabin interior excluding the window portions, the material cost of the sound absorbing sheet is high, and the operation to install the sound absorbing sheet takes time, leading to an increase in the cost of the operation. Accordingly, there is room for improvement in terms of cost reduction.
Furthermore, in Japanese Unexamined Patent Application Publication 2002-356184, a resonance chamber requiring a space portion which is independent from the cabin interior is provided in the ceiling wall portion of the cabin interior of the working vehicle, and a silencing effect is obtained by providing a pipe from the resonance chamber to the cabin interior such that the resonance frequency component of the engine noise which diffuses through the cabin interior is reduced through attenuation by frictional resistance with the periphery thereof As shown in FIGS. 9 to 12 of the document, however, the resonance chamber is attached to the ceiling wall portion as a downwardly-protruding separate member, and hence there is particular room for improvement in terms of design and safety with respect to an automobile for traveling at high speed.

Sun visor for automobile and sound absorbing structure for an automobile


A hydraulic damper is disclosed which has a contraction phase one-way passage way which allows a flow of damping fluid in contraction phase, an extension phase one-way passage way which allows a flow of damping fluid in extension phase, and a valve element in the form of a hollow control rod. The valve element has a neutral position in which both of the contraction phase and extension phase one-way passage ways are open, a first displaced position in which the extension phase one-way passage way is restricted with the contraction phase one-way passage way left open, and a second displaced position in which the contraction phase one-way passage way is restricted with said extension phase one-way passage way left open.

The present invention relates to a hydraulic damper for a vehicular suspension system.
Hydraulic dampers used in vehicular suspension systems cannot cope well with input from the road surface such that if a hydraulic damper is set to a hard damping force range position and undergoes extension phase, an impact due to engagement of the associated tire with a bump of the road surface is directly transmitted to the vehicle body, while if the hydraulic damper is set to the hard damping force range position and undergoes contraction phase, the hydraulic dampler cannot extend enough to cope with a pot hole of the road surface, subjecting the vehicle body to a rapid drop.
An object of the present invention is to provide a hydraulic damper wherein the damping force characteristic for one of contraction and extension can be varied in an independent manner from the damping force characteristic for the other phase.


This method for manufacturing a silicon epitaxial wafer includes: a step of growing an epitaxial layer having silicon on a silicon wafer having a main surface of {110}; and a cooling step of cooling the silicon wafer after growing the epitaxial layer. In a first aspect, in the cooling step, a rapid cooling at a cooling rate of more than 500° C./minute is performed in a range of 750° C. to 650° C. In a second aspect, in the cooling step, a passivation film is grown on a main surface of the epitaxial layer at a temperature of 720° C. or more. In a third aspect, a single crystal silicon wafer in which a misorientation angle of a main surface of {110} surface is in a range from 3.0° to 6.2° inclined towards a <110> direction perpendicular to the main surface or a <111> direction is used as the silicon wafer.

1. Field of the Invention
This invention relates to a silicon epitaxial wafer of which a main surface is {110} and a method for manufacturing the same, and more specifically relates to a silicon epitaxial wafer with high quality having low surface roughness and a manufacturing method thereof.
This application claims priority on Japanese Patent Application No. 2004-285369, filed on Sep. 29, 2004, the content of which is incorporated herein by reference.
2. Background Art
In general, a single crystal substrate having a main surface of {100} or {111} is used as a substrate for manufacturing a silicon epitaxial wafer; however in some cases, {110} single crystal substrates are used for some special MPUs and applications of semiconductor pressure sensors.
In a silicon epitaxial wafer manufactured using a single crystal substrate having a main surface of {110}, there are cases in which periodic stripe-like irregularities and surface roughening occur in a surface as shown in FIG. 6.
With regard to its surface roughness, for example, a roughness (Rms) measured by an atomic force microscope (AFM) may be 0.2 nm or more, and a P-V value may be 1.5 nm or more.
In the case in which those irregularities and surface roughening are large, the surface appears to be colored such as white, brown, or iridescent or appears to be clouded when observed visually under a high-luminance converged light. The surface roughening is likely to be caused by a formation of facet structures in a Si (110) surface as described in Non-Patent Document 1. In the case in which the irregularities due to the formation of these facet structures become excessively large, for example, they may cause defective characteristics in a semiconductor device fabricated thereon.
Therefore, those surface irregularities and surface roughening must be reduced.
Examples of a method for manufacturing a silicon epitaxial wafer using the above-mentioned single crystal substrate having the main surface of {110} may include a method in which an epitaxial growth is performed on a silicon single crystal substrate having a surface orientation of (110) (from −0.5° to +0.5°) in a same manner as that performed on a (100) single crystal silicon substrate. In this manufacturing method, as shown in AFM measurement results in FIG. 6, a surface may be formed which has periodic banded irregularities of several nanometers to several dozens of micrometers, or a surface may be formed which has irregularities and on which facets are formed.
As mentioned above, in the case in which those irregularities and surface roughening are large, the surface appears to be colored such as white, brown, or iridescent or appears to be clouded when observed visually under a high-luminance converged light.
Also, In the case in which the irregularities due to the formation of these facet structures become excessively large, for example, defective characteristics may be caused in a semiconductor device fabricated thereon. Therefore, those surface irregularities and surface roughening must be reduced.
(Non-Patent Document 1) Yamamoto et al., J. Appl. Phys. Vol. 75, No. 5, 2421 (1994).

Silicon epitaxial wafer and method for manufacturing the same