A process of preparing a moisture-resistant fluorine containing SiO.sub.x film includes steps of supplying reactant gases containing silicon, oxygen and fluorine into a process chamber and generating plasma in the process chamber, supporting a substrate on a substrate support in the process chamber, depositing a fluorine-containing SiO.sub.x film on the substrate by contacting the substrate with the plasma while maintaining temperature of the film above 300.degree. C., and nitriding an exposed surface of the film with a high density plasma. The silicon and fluorine reactants can be supplied by separate gases such as SiH.sub.4 and SiF.sub.4 or as a single SiF.sub.4 gas and the oxygen reactant can be supplied by a pure oxygen gas. The SiH.sub.4 and SiF.sub.4 can be supplied in a ratio of SiH.sub.4 /(SiH.sub.4 +SiF.sub.4) of no greater than 0.5. The process can provide a film with a fluorine content of 2 to 12 atomic percent and argon can be included in the plasma to assist in gap filling. The plasma can be a high density plasma produced in an ECR, TCP.TM. or ICP reactor and the substrate can be a silicon wafer including one or more metal layers over which the fluorine-containing SiO.sub.x film is deposited. The substrate support can include a gas passage which supplies a temperature control gas into a space between opposed surfaces of the substrate and the substrate support for maintaining the substrate at a desired temperature. The nitriding step can be carried out in less than 1 minute without applying an rf bias to the substrate. The nitriding gas can be N.sub.2, N.sub.2 O and/or NH.sub.3, the nitrogen ion energy can be 20 to 50 eV, the nitrogen flux can be at least 1 mA/cm.sup.2 and the nitrogen gas flow rate can be at least 50 sccm.

CVD apparatus is conventionally used to form various thin films in a semiconductor integrated circuit. Such CVD apparatus can form thin films such as SiO.sub.2, Si.sub.3 N.sub.4, Si or the like with high purity and high quality. In the reaction process of forming a thin film, a reaction vessel in which semiconductor substrates are arranged can be heated to a high temperature condition of 500.degree. to 1000.degree. C. Raw material to be deposited can be supplied through the vessel in the form of gaseous constituents so that gaseous molecules are thermally disassociated and combined in the gas and on a surface of the substrates so as to form a thin film.
A plasma-enhanced CVD apparatus utilizes a plasma reaction to create a reaction similar to that of the above-described CVD apparatus, but at a relatively low temperature in order to form a thin film. The plasma CVD apparatus includes a process chamber consisting of a plasma generating chamber which may be separate from or part of a reaction chamber, a gas introduction system, and an exhaust system. For example, such a plasma-enhanced CVD apparatus is disclosed in U.S. Pat. No. 4,401,504 and commonly-owned U.S. Pat. No. 5,200,232. Plasma is generated in such an apparatus by a high density microwave discharge through electron-cyclotron resonance (ECR). A substrate table is provided in the reaction chamber, and plasma generated in the plasma formation chamber passes through a plasma extracting orifice so as to form a plasma stream in the reaction chamber. The substrate table may include a radiofrequency (rf) biasing component to apply an rf bias to the substrate and a cooling mechanism in order to prevent a rise in temperature of the substrate due to the plasma action.
A plasma apparatus using high density ECR for various processes such as deposition, etching and sputtering to manufacture semiconductor components is disclosed in U.S. Pat. No. 4,902,934. Such a plasma apparatus includes an electrostatic chuck (ESC) for holding a substrate (such as a silicon wafer) in good thermal contact and in a vertical orientation. The chuck can also be provided with cooling and heating capabilities. In general, such reaction chambers can be operated under vacuum conditions, and the plasma generation chamber can be enclosed by walls which are water-cooled. Other types of reactors in which deposition can be carried out include parallel plate reactors and high density transformer coupled plasma (TCP.TM.), also called inductively coupled plasma (ICP), reactors of the type disclosed in commonly owned U.S. Pat. Nos. 4,340,462 and 4,948,458.
Electrostatic chucking devices are disclosed in U.S. Pat. Nos. 3,993,509; 4,184,188; and 4,384,918. With such systems, a wafer substrate is typically located on a dielectric layer, and the wafer supporting surface of such electrostatic chucking arrangements can be larger or smaller than the wafer substrate supported thereon. The electrostatic voltage and rf bias are applied to an electrode buried within a dielectric layer and proximate to the wafer/substrate contact surface.
In semiconductor processing, devices are being built with smaller wiring pitches and larger interconnect resistances. In order to reduce delays in critical speed paths, it has been proposed to embed low dielectric constant material between adjacent metal lines or lower the dielectric constant of the intermetal dielectric material by adding fluorine thereto. A paper presented at the Feb. 21-22, 1995 DUMIC Conference by L. Qian et al., entitled "High Density Plasma Deposition and Deep Submicron Gap Fill with Low Dielectric Constant SiOF Films" describes deposition of up to 10 atomic % fluorine-containing moisture resistant SiOF films on a silicon sample at room temperature using high density plasma. This paper states that fluorine in the film can be reduced by adding hydrogen to the SiF.sub.4 +O.sub.2 +Ar deposition gas chemistry, the film had a dielectric constant of 3.7, and the refractive index was lowest for deposition conditions where the SiF.sub.4 :SiF.sub.4 +O.sub.2 ratio was 0.29.
Another paper presented at the DUMIC Conference is by D. Schuchmann et al., entitled "Comparison of PECVD F-TEOS Films and High Density Plasma SiOF Films." This paper mentions that fluorinated TEOS films have been used for gap filling and compares such films to films deposited by high density plasma (HDP) inductively coupled plasma using SiF.sub.4 +O.sub.2 +Ar. The HDP films were found to have better moisture and thermal stability than the F-TEOS films.
Other papers presented at the DUMIC Conference include "Preparation of SiOF Films with Low Dielectric Constant by ECR Plasma CVD" by T. Fukada et al., "An Evaluation of Fluorine Doped PETEOS on Gap Fill Ability and Film Characterization" by K. Hewes et al., "Dual Frequency Plasma CVD Fluorosilicate Glass Water Absorption and Stability" by M. Shapiro et al., and "Water-absorption mechanisms of F-doped PECVD SiO.sub.2 with Low-Dielectric Constant" by H. Miyajima et al. Of these, Fukada discloses that SiOF films deposited by rf biased ECR plasma are superior to SOG and TEOS-O.sub.3 films, the SiOF films providing excellent planarization and sub half micron gap filling without voids. Moreover, according to Fukada, the dielectric constant of SiOF films can be reduced from 4.0 to 3.2 by increasing the SiF.sub.4 /(SiF.sub.4 +SiH.sub.4) gas flow ratio in an rf-biased ECR plasma CVD process using SiF.sub.4, SiH.sub.4 and O.sub.2 gas reactants (O.sub.2 /(SiF.sub.4 +SiH.sub.4)=1.6) and a substrate held on a water cooled electrostatic chuck. Hewes discloses CVD of fluorosilicate glass films from TEOS, O.sub.2 and C.sub.2 F.sub.6 introduced into a reaction chamber by a showerhead gas mixer. Shapiro discloses that ULSI device speed can be increased by reducing capacitance of the interlevel insulator such as by adding fluorine to SiO.sub.x films but water incorporation into the films raises the dielectric constant and water evolution can produce voids or corrosion in surrounding metal. Miyajima discloses that water absorption of F-doped SiO.sub.2 films containing more than 4% F is a serious problem because it causes degradation of device reliability and film adhesion properties and that the resistance to water absorption is lower for films deposited by parallel plate plasma CVD compared to high density helicon-wave plasma using TEOS, O.sub.2 and CF.sub.4 as deposition gases.
The effects of thermal annealing on the densification of SiO.sub.2 prepared by liquid-phase deposition at 15.degree. C. is described by C. Yeh et al., in "Controlling Fluorine Concentration and Thermal Annealing Effect on Liquid-Phase Deposited SiO.sub.2-x F.sub.x Films", J. Electrochem, Vol. 142, No. 10, October 1995. Yeh discloses that restructuring occurs during annealing because H atoms between F and O atoms are very electronegative and annealing at 300.degree. to 500.degree. C. can break SiO--H bonds forming SiO.sup.- whereas annealing higher than 700.degree. C. also breaks SiF bonds forming Si.sup.+.
As integrated circuits become smaller and faster, there is a need to reduce the dielectric constant of the intermetal dielectric to prevent degradation of the pulse propagation and to reduce the device power consumption. One technique for achieving dielectric constant as low as 3.4 is by the addition of fluorine to SiO.sub.2. Fluorine doped SiO.sub.2 is commonly referred to as "FSG." FSG can be obtained in several ways such as by the addition of C.sub.2 F.sub.6 to a TEOS (tetraethoxysilane)/O.sub.2 deposition process or by plasma deposition using a mixture of SiF.sub.4 /O.sub.2 or a mixture of SiF.sub.4, SiH.sub.4 and O.sub.2.
The preferred method of FSG deposition utilizes a high density plasma source because of its demonstrated superiority in the gap filling of narrow, high aspect gaps between adjacent metal lines. One negative feature common to FSG processes is that the resulting dielectric material is hydrophilic, i.e. it absorbs moisture from the atmosphere via SiOH bonding which can result in a time dependent increase in the dielectric constant referred to as "drift." This dielectric constant drift is referred to as film instability.
As disclosed in copending application Ser. No. 08/604,018, film stability can be improved by carrying out the deposition at a process temperature greater than 300.degree. C. with SiF.sub.4 constituting more than 50% of the silicon bearing deposition gas. Although the film stability can be greatly improved, the dielectric constant can increase as much as 0.1 after one week exposure to atmospheric moisture starting from a dielectric constant of 3.5 or less. Such atmospheric exposure could occur as a result of storage time in a semiconductor fab while the wafers wait for the next processing step. For purposes of this discussion, "instability" is defined as the change in dielectric constant, .DELTA.k, when the film is left in air at ambient temperature (e.g. typically 50.+-.10% relative humidity in a fab) for 7 days. The dielectric constant is measured at least five times during the 7 day period and a least squares linear or quadratic fit to the data is used to calculate the drift at 5 days. For stability, this number is preferably less than 0.05.
Takeishi et al. investigated the film stability effects of annealing an oxide film in N.sub.2 O, N.sub.2 and O.sub.2 (J. Electrochem. Soc., 143,381 (1996). According to Takeishi et al., the film was heated to 400.degree. C. in a N.sub.2 O plasma, an N.sub.2 plasma, an O.sub.2 plasma and O.sub.2 without plasma. The film, deposited from plasma enhanced CVD TEOS/O.sub.2 using C.sub.2 F.sub.6 as the fluorine source, showed some improvement in stability for the nitrogen and N.sub.2 O treated films. A major drawback of the Takeishi et al. treatment is that a 30 min. plasma treatment is necessary to achieve stability improvement. Such a lengthy treatment presents serious problems in implementation as a production process using single wafer processing technology.
Hattangady et al. investigated a process for nitriding the surface of a gate oxide by exposing the oxide to a remotely generated He--N.sub.2 plasma. According to Hattangady et al., a surface nitridation of an SiO.sub.2 film increases with increasing temperature and saturates with a sufficiently long exposure time on the order of about 50 minutes.

Method for preparing nitrogen surface treated fluorine doped silicon dioxide films


The present invention is directed to an LED light fixture. The LED light fixture comprises an interface for connecting the fixture to a source of electrical power, a power control section for supplying and controlling power to an LED array producing a light of a suitable intensity and color for the task for which the fixture is to be used and a light diffuser for diffusing the light from the LED array. The present invention is also directed to a novel power control for supplying and controlling power to an LED array comprising a non switching linear design based on a monolithic approach of power control whereby the load (the LED array) becomes part of the power control system.

A common lighting source used in residential and commercial lighting is incandescent light bulbs that produce light using a wire filament which is heated up by the electrical current running through the filament contained within a vacuum which may also contain a mercury vapor or halogen atmosphere. Many problems exist with these light bulbs in that such bulbs fail frequently, produce large amounts of heat and use significant amounts of electricity to produce light. These disadvantages result in high maintenance costs, rises in room temperature and unnecessary energy consumption.
There have been attempts to improve the efficiency of such light bulbs such as, for example, the use of lower power fluorescent light bulbs which can be utilized in a standard incandescent light bulb screw base fixture. While such bulbs do use less power, the problem of the mercury vapor atmosphere within the bulb is still present which can create environmental problems on disposal.
In many industrial and commercial areas, another common lighting source is fluorescent light bulbs which produce light by passing electrical current through a mercury vapor atmosphere within the bulb. Such fluorescent light bulbs have the advantage that they use less power than incandescent light bulbs that produce light by heating up a wire filament as well as not producing the same amount of heat as that produced by an incandescent bulb.
However, such bulbs still have problems in that they fail frequently resulting in high maintenance costs and the mercury vapor atmosphere within the bulb can cause environmental problems on disposal.
There have also been attempts in the past to replace various types of incandescent light bulbs with LED light bulbs such as shown in U.S. Pat. No. 6,609,804. However, such LED light bulbs do not easily replace incandescent light sources, nor are they significantly more energy efficient for the same light output. In addition, there does not appear top have been attempts made to replace fluorescent light fixtures with LED light sources.
Thus, there still remains a need for a light fixture which can easily replace standard residential and commercial light fixtures but use less power, run cooler and have a longer life span.

LED control utilizing dynamic resistance of LEDs


The invention relates to fuel composition formed by a fuel mixture, whose one component is formed by partially dewatered stillage from the bioethanol production and the other one are milled materials, where the ratio of total of sodium weight and potassium weight in the ashes to the weight of the other non-combustible components of a value less than 1:5.85 and/or it set up to achieve the resulting ash melting temperature of the mixture higher than 760° C.

In agricultural production, a number of residues is originated in the elaboration of agricultural products, which are occasionally further treated, e.g. wood chips to produce cellulose, corn straw as litter or corn stalks for silage. In case the supply of the above materials exceeds their demand, it is possible to use some of them, e.g. wood chips, for the generation of energy by their combustion, nevertheless, other materials, e.g. corn straw, cannot be simply burnt down and if grate boilers of special design are not used, e.g. boilers with water-cooled grates in which combustion gases are cooled down in the combustion chamber, it is necessary to apply the inefficient deposition.5
Most materials considered as fuels have a high ash-melting temperature, usually of more than 1,300° C. Other materials containing carbon and thus potentially combustible materials, such as corn straw, pressed work from the production of methyl ester, or residues from the production of sunflower-seed oil, have a lower ash-melting temperature, which is usually in the range of 850-1,050° C. Specifically, the ash-melting temperature of corn straw is about 850° C., of corn and meals from corn 620 to 750° C. and even less, of residues from sunflower-seed production 1,010° C., pressed work from rape-seed methyl esters about 1,210° C. The low ash-melting temperature causes build-up of slag in the combustion chamber, in the boiler combustion space and even on the heat transfer surfaces and thus it challenges the operation of the boiler and sometimes even makes its operation impossible. In fluidized bed boilers, these materials are not burnt due to the low temperature of ash matter.
At present, due to the efforts to get rid of the dependence on in the import of fossil fuels, in particular crude oil, the interest in the use of hitherto unused organic matter, especially waste organic matter, for the production of energy, has been growing. The interest is especially focused on the production bioethanol, which could be produced in every country from its local agricultural crops and thus crude oil could be replaced for the greater part with it. For the production bioethanol, sugary and starch crops can be used, in particular sugar beet and cereals. Produced bioethanol can be used directly in the combustion engines as fuel, nevertheless, at present it is usually used as an admixture, which is added in the amounts of 5% to 10% to the conventional mineral fuels. Using ethanol, the octane number is increased and the amount of CO2 emissions decreased.
The sugarcane ethanol has found its wide application especially in Brazil, where it is used as automotive fuel. In the 80-ies of the last century, approximately two-thirds of cars in Brazil had their engines specially adapted for the combustion of pure bioethanol. At present, the new cars are not adapted in this way any more, nevertheless, all motor-vehicle petrol in Brazil contains 26% of sugarcane bioethanol. Current combustion engines can run on this mixture.
The bioethanol produced from maize is also used as a fuel additive to most automotive petrols in the USA, usually as a 10% admixture.
The waste in the production of bioethanol from maize, cereals or sugarcane, sugar beet is stillage. The stillage could also be potentially used as fuel, nevertheless, due to its low ash-melting temperature, it is not used as fuel. At present, the stillage is usually centrifuged on a centrifuge, the solid fraction, called cake, is dried in a steam drier or a drum drier, where the drier heating medium is fossil fuel. The liquid fraction, called centrate, is condensed in multi-stage evaporators to obtain syrup, which is added to the solid fraction, the cake, and it is dried together with it in a steam drier or a drum drier. Thus a by-product is produced, which is used as a forage mixture in the form of dried granules. The unused part is also dumped into the sea in the countries having appropriate conditions for it.
The major part of stillage, especially due to the ever growing production of bio-ethanol, is thus not used any more, it goes beyond its use as forage, and thus it is indispensable to look for other possibilities of its application. Its direct combustion is thus impossible, as stillage without drying has low caloric power and it usually contains approx. 90% of water. If stillage is dried to 40-30-10% of moisture content, its caloric power would increase to approx. 9-13-17 MJ/kg. From the aspect of energy, such dried stillage is thermally self-supporting, which lays down one of the prerequisites for its combustion in current boilers. Nevertheless, it has been found that dried stilled can not be combusted in current boilers, at least nobody has been successful in it so far due to its low-temperature melting ashes. When combusting this sort of stillage, the low melting temperature of ashes both in grate boilers and the fluidized bed boilers and dry bottom boilers results in the fact that melted ash agglomerates the fluidized bed, it forms slag in the furnace and on the heat exchange surfaces of the boiler, resulting in a breakdown of the boiler, which is put out of service in a matter of a few minutes.
The experts have been hitherto of the opinion that the problem of exploiting biowaste with low ash-melting temperature could be solved by adapting the boiler. Nevertheless, up to now nobody has succeeded in it.
Another possible method of exploiting stillage is the system in which the liquid stillage as a whole is conveyed to the biogas station to produce biogas from it. The disadvantage of this method is the fact that biogas is produced only from the liquid fraction of the stillage and thus the solid fraction is practically wasted. Prolongation of the decomposition time would increase the biogas yield, nevertheless, it would be at the price of higher investment and operation costs. In addition to it, the solid residue after the utilization of stillage in the biogas station would be higher by 50%, even in case of a very long fermentation period. This system thus does not find any solution to the problem of the stillage solid fraction.

Fuel for obtaining thermal energy from biomass with low-ash melting temperature, in particular from stillage from bioethanol processing


A retractable ventilation system for a household appliance includes a lifting motor for moving the ventilation system in two opposing directions, and a switch controlling movement of the lifting motor. A first actuation of the switch moves the ventilation system in a first (or preferred) of the two directions, and a second actuation of the switch moves the ventilation system in a second direction opposing the first direction. Furthermore, a household appliance includes an extractor hood, a cooking appliance or a combination thereof, and at least one of the proposed retractable ventilation systems. A method for operating the retractable ventilation system is also described.

The invention relates to a retractable ventilation system for a household appliance as well as a household appliance having at least one such ventilation system. The invention also relates to a method for operating the ventilation system.
Retractable tabletop ventilation systems are known which work like extractor hoods but can be recessed into a surface (e.g. a kitchen worktop or a table). Typically retractable tabletop ventilation systems are disposed in the immediate vicinity of a cooktop, from the operator's perspective generally behind the cooktop. Such retractable tabletop ventilation systems are frequently also referred to as downdraft extractors. Thus it is possible that e.g. during cooking the retractable tabletop ventilation system is extended and then retracted again as soon as it is no longer required. The retractable tabletop ventilation system can for example comprise a suction housing or an air intake, either of which can be extended for suction.
It is known for the retractable tabletop ventilation system to be operated with a single button, which when operated once extends the system and when operated afresh retracts it again. Certain safety criteria have to be satisfied here, so that the possibility of trapping e.g. a hand or a finger in the retractable tabletop ventilation system when it is being retracted is effectively prevented.
In this respect it is known for operation to be implemented by means of the single button incorporating safety circuits using microcontrollers or integrated semiconductor components. However, the disadvantage of this is that the safety circuits are configured separately from the actual actuation of the lifting motor. A further disadvantage is that this solution is relatively expensive, because firstly a microcontroller with corresponding programming is required and secondly the safety circuits with associated actuation must be provided.


A method, system, and program product for remotely attesting to a state of computing system is provided. Specifically, the present invention allows a remote system to establish trust in the properties of the computer system. The properties to be trusted are expanded from the usual system software layers and related configuration files to novel types of data such as static data specific to the computer system, dynamic data determined at system startup, or dynamic data created as the computer system runs applications.

1. Field of the Invention
This invention relates to remotely establishing the specific or dynamic properties of a computer system. More specifically, it relates to remotely establishing trust in properties of a computer system.
2. Related Art
Current Trusted Computing Group (TCG) use cases provide the means for remote parties to attest to the software state of a computer system/platform. The software state includes measurements of the software chain, and might include configuration files used to initialize or customize a software module. The attestation method, as described in TCG documents, begins with a Core Root of Trust for Measurement (CRTM) that measures the software and possibly configuration files of the next layer of software to run. Each layer in turn measures the next layer before calling it. Digests of these measurements are extended through a one-way hash function into Platform Configuration Registers (PCRs) contained in a Trusted Platform Module (TPM). The measurement names and values are also appended to a measurement list.
During the remote attestation process, a set of PCRs is quoted—digested, and digitally signed with a trusted Attestation Identity Key (AIK). The remote party/system validates the AIK certificate issued by a trusted privacy certificate authority, the digital signature of the quote, and the integrity of the measurement list by comparing it to the PCR state included in the quote. Once the measurement list is trusted, the remote system uses it to determine whether the attesting system is running trusted software.
Current uses measure known, expected, constant, system-independent data. A typical measurement is a software stack, from bootstrap loader, through Operating System load, and finally application load. Remote systems doing an attestation are expected to have known good values. Even when other data such as configuration files are measured, the literature envisions a limited number of variations among systems, a relatively homogeneous environment.
By measuring data common to many systems, and by storing only static data, not data generated at run time, the remote system needs to store only a small list of trusted measurements (software modules or configuration files), and can use that list to attest a large number of systems across an enterprise. While this attestation is valuable for trusted computing, it does not address establishing trust in data that may be specific to a system or even data that may be generated or changed as the system runs.
For example, there are currently mechanisms to establish secure communication tunnels, usually based on public key certificates (e.g., SSL, IPSEC, and Web Services Security). There are also techniques to establish properties of remote systems using the TPM or other core root of trust elements. Unfortunately, these two separate mechanisms do not ensure that the system for which properties are established during remote attestation is the same system at which the protected tunnel ends. This is essential for establishing security guarantees in distributed environments. One known solution is to create trusted third parties that "vouch" that certificates used during remote attestation and certificates used to establish secure tunnels belong to the same system. Drawbacks of known solutions include (among others): (1) third parties are difficult to establish; (2) third parties are currently unable to solve key revocation in a scalable and cost-efficient way; and (3) it is extremely difficult to find commonly trusted parties in heterogeneous distributed environments.
In view of the foregoing, there exists a need for a solution that solves at least one of the deficiencies in the related art.

This patent is subject to a terminal disclaimer.

Method, system, and program product for remotely attesting to a state of a computer system

International Business Machines Corporation


An apparatus positions a transducer, carried by a slider, over a track on a magnetic disk. An arm has a first end for attachment to an actuator for rotating the arm and a second end for attachment to the slider. The arm also has an arm portion extending between the first and second ends. A shape memory alloy is coupled to the arm portion. Thermal energy is selectively applied to the shape memory alloy to cause corresponding deformation of the shape memory alloy causing the arm portion to deflect and move the second end along an arcuate path in a plane substantially transverse to the track.

The present invention relates to positioning an arm over tracks on a disk. More particularly, the present invention relates to centering a transducer over information-carrying tracks on a magnetic disk.
In disk drive systems, there is typically a stack of disks where the disks are spaced apart and mounted on a spindle. Data heads, which carry transducers that read and write information on the disks, are attached to arms which extend between the disks so that the data heads fly over the disks. The arms are attached to an actuator which is moved to position the data heads over data tracks on the disks. If the data heads are to reliably read and write information on the disk, the transducers must be centered over the data tracks. Therefore, a closed loop feedback system is desirable for positioning the data heads over the tracks.
One method of positioning the data heads in the disk drive system over the tracks on the disk which uses a closed loop feedback circuit is called the dedicated servo method. In the dedicated servo method, one data head and one disk in the disk drive system are dedicated to the task of acquiring position information. The dedicated data head is referred to as to the servo head and the dedicated disk is referred to as the servo disk. The servo head is connected to a designated servo arm which is coupled to the same actuator as the other arms. The servo head is held over the center of a desired track on the servo disk by a closed loop servo system which utilizes feedback from specially written data on the servo disk to properly position the actuator. Since the other arms are rigidly attached to the actuator, they follow the servo arm and are positioned over the desired tracks on their respective disks.
Although the servo head is in the closed loop feedback system with the servo disk, the other data heads and other disks in the disk drive do not have the benefit of a separate closed loop feedback system to assure that they are properly positioned. Thus, in order to function properly, the other disks and heads must maintain their original position with respect to the servo head and the servo disk over extended periods of time. Maintaining this position is often difficult because of shifts in the relative head position due to temperature extremes and mechanical wear. If all the data heads, arms and disks do not maintain their positions relative to the servo head and the servo disk, off-track errors will result. Off-track errors reduce read margins and may cause data errors.

Shape memory alloy for centering a transducer carried by a slider in a support arm over a track on a magnetic disk


A hybrid cellular and non-cellular multi-hop communication device, including a hand-held wireless device having one or more antennas, a cellular wireless interface connected to at least some of the one or more antennas, and a non-cellular wireless interface connected to at least some of the one or more antennas. The non-cellular wireless interface may include a rate allocator configured to select a physical-layer rate of transmission of data from the non-cellular wireless interface based on a queue length of data to be transmitted from the hand-held cellular device and a transmitter configured to wirelessly transmit data from the queue and adjust physical-layer transmission parameters based on a physical-layer rate selected by the rate allocator.

Some conventional wireless networks adopt a central authority to manage communications between the nodes of the network and allocate rates for the communications. For example, in a conventional state of the art cellular network, the nodes of the network may include cellular telephones, and other mobile devices configured for enhanced multimedia applications. The communications between such nodes may include both voice and non-voice data traffic, with requirements or preferences for a variety of data rates based on the application.
FIG. 1 depicts an exemplary conventional cellular network 100. A central authority 110, such as a base station is commonly employed to manage the traffic and allocate data rates in cellular network 100. The devices at any two nodes of the cellular network 100, such as 104 and 106 may communicate with each other by routing all communications via the central authority 110. The communication link between a node and central authority 110 is commonly referred to as a "single hop." Links 120, 130, 140 and 150 represent single hops between nodes 102, 104, 106 and 108 respectively and central authority 110.
Some current technology is limited to single hops. Consequently, in some instances, this current technology does not permit efficient communication between the two nodes 104 and 106 without the involvement of central authority 110. The involvement of the central authority 110 leads to well known problems, such as, for example in cellular phone networks: dropped calls, low reception, increased drain on battery life, etc., because the devices at individual nodes may not always be located at sufficient proximity to the base station, or the base station may be limited in the amount of traffic it can handle.
Accordingly, multi-nodal network implementations that do not always depend on a central authority for certain functions have been explored. Such implementations are commonly known as "distributed" or "ad-hoc" networks, wherein each node is configured to manage its own data transmission without always requiring relatively heavy involvement of a central authority. A common problem encountered in distributed network implementations is that of interference among several communicating nodes located in close proximity to one another. Another problem is the issue of efficient resource allocation of the wireless medium. Data intensive applications are commonly supported by mobile devices, and without a central authority to handle resource allocation, some nodes may consume the available communication channel while starving other nodes.
Therefore, certain existing implementations of distributed networks have been limited by requiring knowledge at each node of other nodes in the system in order to allocate system resources among the nodes. However, over a large number of nodes, and with high data traffic, some implementations known in prior art are often rendered very inefficient, leading to high overheads and low throughputs. Accordingly, there is a need in the art for distributed rate allocation among the several nodes in a throughput-optimal or throughput-cognizant manner, wherein interference is minimized or reduced and knowledge at each node of every other node is not required.
Further, certain wireless networks, including single hop and multi-hop, centralized and decentralized wireless networks, do not adequately select the rate at which constituent wireless devices, or nodes, attempt to transmit data. Selecting an appropriate rate may be particularly challenging when wireless devices use shared resources of a wireless medium, e.g., shared frequencies, shared times, shared codes, and in systems with beam forming, shared directions, or other orthogonalizations, and combinations thereof, for example. For instance, in some wireless networks, wireless devices attempt to maximize the rate of transmission of that wireless device without adequately accounting for the effect of that transmission on the ability of other wireless devices to share the same shared resources of the wireless medium, potentially resulting in a lower collective date rate for the network as a whole. Additionally, in some wireless networks, wireless devices do not share the same resources of the wireless medium, in part, because it is difficult to determine whether the transmissions of one wireless device are colliding with the transmissions of another wireless device and preventing resolution of signals from the other wireless device.

Distributed rate allocation and collision detection in wireless networks

Board of Regents, The University of Texas System


The encoder/decoder system uses encoder hardware to encode data symbols and form a data code word. To decode, the system uses the same encoder hardware to determine a residue r(x), i.e. ##EQU1## where C.sub.r (x) is the retrieved code word and g(x) is the generator polynomial. If the residue is all zeros, the ECC code word is error-free and the system need not calculate the error syndrome. If the residue is non-zero, the encoder hardware is used, with various switches in different settings, to include certain multipliers in and exclude other multipliers from the further decoding operations of encoding the residue symbols to produce partial error syndromes that are the coefficients of the error syndrome polynomial.

The importance of error correction coding of data in digital computer systems has increased greatly as the density of the data recorded on mass storage media, more particularly disks, has increased. With higher recording densities, a tiny imperfection in the recording surface of a disk can corrupt a large amount of data. In order to avoid losing that data, error correction codes ("ECC's") are employed to, as the name implies, correct the erroneous data.
Before a string of data symbols is written to a disk, it is mathematically encoded to form ECC symbols. The ECC symbols are then appended to the data string to form data code words--data symbols plus ECC symbols--and the data code words are written to or stored on the disks. When data is to be read from the disks, the data code words containing the data symbols to be read are retrieved from the disks and mathematically decoded. During decoding any errors in the data are detected and, if possible, corrected through manipulation of the ECC symbols For a detailed description of decoding see Peterson and Weldon, Error Correction Codes, 2d Edition, MIT Press, 1972!.
Stored digital data can contain multiple errors. One of the most effective types of ECC used for the correction of multiple errors is a Reed-Solomon code For a detailed description of Reed-Solomon codes, see Peterson and Weldon, Error Correction Codes!. To correct multiple errors in strings of data symbols, Reed-Solomon codes efficiently and effectively utilize the various mathematical properties of sets of symbols known as Galois Fields, represented "GF(P.sup.q)", where "P" is a prime number and "q" can be thought of as the number of digits, base P, in each element or symbol in the field. "P" usually has the value 2 in digital computer applications and, therefore, "q" is the number of bits in each symbol.
To correct errors in the data code words, the error syndrome polynomial is produced. The error syndrome polynomial is used, in turn, to produce error locator and error evaluator polynomials, which are used, respectively, to determine the locations and values of the code word errors.
In many prior known systems separate encoders and decoders are used to encode and decode the data code words. Thus, there is hardware that is not in use for one of the encoding or decoding operations.
In certain other prior known systems the decoders are modified, to also perform the encoding operation. These systems generally use a hardware configuration that is described in a 1992 article by Fettweis and Hassner entitled "A combined Reed-Solomon Encoder and Syndrome Generator with Small Hardware Complexity," IEEE Int. Symp. on Circuits and Systems pp. 1871-1874. This hardware saves on gate count over the separate encoder and decoder, but has latency problems, as discussed in the article.
We have invented an encoder/decoder that has a reduced gate count over separate encoders and decoders, and does not have the latency problems of the Fettweis and Hassner configuration. A modified version of this encoder/decoder can also be used to encode and decode with the modified Reed Solomon codes described in a co-pending U.S. patent application Ser. No. 08/749,235 entitled MODIFIED REED SOLOMON CODE SELECTION AND ENCODING SYSTEM, which is assigned to a common assignee and included herein by reference. The modified Reed Solomon codes encode w-bit data symbols over GF(2.sup.w+i) to produce (w+i)-bit ECC redundancy symbols. The encoding operations involve further manipulating the (w+i)-bit ECC redundancy symbols and a number of "pseudo redundancy symbols," to form a data code word with symbols in GF(2.sup.w). The decoding operations decode the data code word, including the ECC symbols and the pseudo redundancy symbols, to reproduce error-free w-bit data symbols.


A full support mainshaft and fifth gear design that solves the problem of fifth gear failure on NV4500 transmissions. The first embodiment comprises a sleeve that is installed over the smooth support surface of a factory mainshaft. The second embodiment is a mainshaft comprising a support shoulder, splined area, and threaded area. The sleeve of the first embodiment and support shoulder of the second embodiment are slightly greater in diameter than the splined area on the mainshaft. The inside of the gear of the present invention has both a smooth bore area and a splined area. The gear is press fit onto the mainshaft, and in the first embodiment, a spring washer, flat nut and clamp-style nut are installed on the mainshaft after the gear. In the second embodiment, a spring washer, first flat nut, tanged washer, second flat nut and lipped nut are used.

1. Field of the Invention
The present invention relates to the field of automotive transmissions, and more particularly, to a full support mainshaft and fifth gear design for the New Venture/MTM NV4500 transmissions.
2. Description of the Related Art
"Losing" fifth gear is a common complaint with the NV4500 transmissions, particularly when they are coupled to a diesel engine. Although the nut is often blamed, it is actually the mainshaft that fails. The problem is caused by inadequate support of the gear on the mainshaft.
The factory gear is fully splined on its inner surface. On the outside of the gear, approximately half the gear is covered with gear teeth. In the area below the gear teeth, only the tips of the inner gear splines are in contact with the smooth support area of the mainshaft. Thus, the gear is not adequately supported by the mainshaft, and the tips of the splines actually wear into the smooth support area of the mainshaft until the gear is no longer a press fit to the shaft. Once the gear is loose, it either works the mainshaft nut loose until it spins off, which allows the gear to move backward and out of alignment with the mating countershaft gear, or the gear spins on the shaft even though the nut stays on. In either case, the ability to use fifth gear is lost. Installing a new fifth gear and/or nut on a worn mainshaft is only a short-term repair, and the imbalance caused by the wobbling gear often results in transfer case damage. Welding the gear onto a worn mainshaft does not work, nor does LOCTITE®, a high-performance adhesive manufactured by Henkel Technologies. Fifth gear is no longer available until the transmission is repaired.
Both the original equipment manufacturer and the aftermarket have introduced various nut designs in an effort to remedy this problem and keep the gear on the shaft. Aftermarket manufacturers have also tried to correct this problem with two variations of mainshafts that have full-length splines for the fifth gear. The first variation of the aftermarket mainshaft was designed for a fairly light press fit between the gear and shaft. It also uses a spring washer and flat nut to hold the gear onto the shaft. The second variation of the aftermarket mainshaft uses a slip fit between the gear and shaft plus a three-piece thrust washer (consisting of a split washer and a retaining ring) between the mainshaft lock washer (a spring washer) and fifth gear. None of these "fixes" has been successful in preventing fifth gear failures.
FIGS. 1–14 illustrate the prior art. FIG. 1 is a perspective view of a new factory mainshaft 1 without the gear. This figure shows the splines 2, smooth support area 3, and threaded area 4 of the mainshaft. The gear fits over the splines 2 and the smooth support area 3.
FIG. 2 is a partial perspective view of a factory mainshaft 1 with the factory gear 5, spring washer 6 and flat nut 7. The washer 6 and nut 7 fit over the threaded area 4 of the shaft. In an early attempt to solve the problem of the gear working itself off of the shaft, the spring washer 6 was added between the gear 5 and the nut 7. The addition of the washer, however, did not solve the problem.
FIG. 3 is an exploded perspective view of the factory gear 5, spring washer 6 and flat nut 7 of FIG. 2. The nut 7 comprises notches 7a that allow the nut to be turned with a wrench. In the prior art, the nut typically has a beveled edge (not shown) facing the spring washer. The beveled edge has no functional purpose.
FIG. 4 is a perspective view of the factory gear 5 showing the full inner splines 8. As shown in this figure, the splines are triangular in shape with blunt (as opposed to pointed) tips.
FIG. 5 is a partial perspective view of a used factory mainshaft 1 showing the area where the gear 5 (not shown) wears into the shaft. As shown in this figure, the smooth support area 3 is no longer smooth but actually has subtle indentations that have been worn into it by the gear splines 8 (see FIG. 4). These indentations cause the gear to work loose. Once the gear is loose, it works the nut and washer loose, which leads to fifth gear failure. Note that the diameter of the support surface 3 on the factory mainshaft 1 is smaller in diameter than the splined area 2. That difference in diameter is a key factor in the problem addressed by the present invention.
FIG. 6 is a perspective view of the first aftermarket mainshaft variation without the gear. This variation is a press fit aftermarket shaft 9. As shown in this figure, there is no smooth support surface 3 (see FIGS. 1 and 5). Instead, the splined area 10 has been extended so that the entire area below the gear is splined. The shaft still contains a threaded area 4, which further comprises a keyslot 11. The purpose of the keyslot 11 is illustrated in FIGS. 7 and 8.
FIG. 7 is a partial perspective view of the aftermarket mainshaft 9 shown in FIG. 6 with the factory gear 5, spring washer 6 and lipped nut 12. The washer 6 and nut 12 fit over the threaded area 4 of the shaft. The lipped nut 12 represents another attempt to solve the problem of the gear working loose. With this type of nut, part of the lip 12a is bent and pressed down into the keyslot 11. The thought was that the lip 12a in the keyslot 11 would prevent the nut 12 from coming loose, even if the gear 5 came loose. This nut design did not work either. FIG. 8 is an exploded perspective view of the factory gear 5, spring washer 6, and lipped nut 12.
FIG. 9 is a perspective view of the second aftermarket mainshaft variation without the gear. This variation is a slip fit aftermarket mainshaft 13 showing a groove 14 for a split washer (shown in FIG. 10). The groove is located between the splined area 10 and the threaded area 4. As with the press fit aftermarket shaft, the splined area 10 is extended so that the entire area below the gear is splined, and the threaded area 4 includes a keyslot 11.
FIG. 10 is a partial perspective view of the slip fit aftermarket mainshaft 13 shown in FIG. 9 with the gear 5, split washer (not shown) and retaining ring 15, spring washer 6, and lipped nut 12. the split washer and retaining ring fit within the groove 14 shown in FIG. 9. The spring washer 6 and nut 12 fit over the threaded area 4 of the shaft. As in FIG. 7, the lip 12a of the nut is pressed down into the keyslot. Because the configuration shown in FIG. 7 was not effective in keeping the gear on the shaft, the split washer (not shown) and retaining ring 15 were added. FIG. 11 is an exploded perspective view of the gear 5, split washer 16 and retaining ring 15, spring washer 6, and lipped nut 12.
None of the designs described above was successful in preventing fifth gear failure, and alternate nut designs were developed with the hope that they would serve to keep the gear on the shaft. FIG. 12 is a perspective view of a clamp-style nut 17. This nut has horizontal screws or clamps 18 that were intended to hold the nut more tightly on the threaded area 4 of the mainshaft. FIG. 13 is a perspective view of a nut with set screws 13. This nut comprises vertical screws 20 that are screwed down against the threads of the threaded area 4 on the mainshaft. Like the other designs described above, neither of these nut designs was effective in solving the problem.
With both the factory shaft and the aftermarket shaft, the gear is not fully supported by the area underneath it on the shaft. With the factory shaft, the smooth support area is smaller in diameter than the splined area so that only the tips of the inner gear splines are in contact with the smooth support area. With the aftermarket shaft, although the area beneath the gear is fully splined, the inner splines of the gear are not fully congruent with the splines on the shaft. This point is illustrated in FIG. 14, which is a partial section view of the gear 5 on an aftermarket mainshaft. The splined area of the mainshaft 10 is shown in relation to the inner gear splines 8. As shown in this figure, there are gaps between the inner gear splines 8 and the splines 10 on the mainshaft. These gaps lead to instability of the gear on the shaft and, ultimately, the loosening of the gear on the shaft.
It is an object of the present invention to solve the problem described above by providing a mainshaft and fifth gear design that affords more adequate support for the gear on the shaft and that does not result in fifth gear failure. It is a further object of the present invention to provide an embodiment that constitutes a retrofit of an existing factory mainshaft and an embodiment that is an entirely new mainshaft design.

Full support mainshaft and fifth gear design


A six-row ball bearing linear guideway is provided with six rows of balls disposed between the slider and the rail. The six rows of balls are symmetrically disposed at two sides of the rail, the balls in the middle and upper rail rolling grooves bear and increase the load capacity in the downward direction. The balls in the lower rail rolling grooves bear a load in the upward direction, and the profile factor of the lower rail rolling grooves is smaller than that of the upper rail rolling grooves, thus the rated static load capacity in the upward direction is improved. The balls in the upper, middle and lower rail rolling grooves all serve to bear the load capacity in the lateral direction, thus the rated static load capacity in the lateral direction is improved. Hence, the rated static load capacity is improved in upward, downward and lateral directions.

1. Field of the Invention
The present invention relates to a six-row ball bearing linear guideway, and more particularly to a ball bearing linear guideway with improved rated static load capacity in the upward, downward and lateral directions.
2. Description of the Prior Art
Ball bearing linear guideway is an important linear transmission device, and has been widely used on different transportation devices because of its advantages of high efficiency and accuracy. Rated static load capacity is an important consideration when choosing ball bearing linear guideways, including the rated static load capacity in the downward, upward and lateral directions. The rated static load capacity of a ball bearing linear guideway is usually in direct proportion to the number of rows of balls and the diameter of the balls. Therefore, increasing the ball diameter or the number of row of the balls is a measure usually taken to increase the rated static load capacity. However, with the continuously increased machines' requirement for rated static load capacity, the rated static load capacity of the existing ball bearing linear guideway is still insufficient and needs to be improved.
FIG. 1 shows a ball bearing linear guideway disclosed in Japan Patent No. 07-035136, which comprises a slider 11 slidably mounted on a rail 12, and four rows of balls 13 disposed between the slider 11 and the rail 12 and symmetrically arranged at both sides of the rail 12. The number of the rows of balls of the ball bearing linear guideway 10 is increased from 2 to 4 as compared with other ball bearing linear guideways, so as to increase the rated static load capacity of the ball bearing linear guideway 10. However, by looking at the arrangements of the four rows of balls 13, we can see that the four rows of balls 13 all come into contact with the rolling grooves in an arc-shaped 45°-45°, namely, a contact angle of the respective balls with respect to the rolling grooves is 45 degrees. Such arrangements at this angle can equally provide load capacities in downward, upward and lateral directions. Furthermore, the ball bearing linear guideway 10 is designed with the same profile factor, so that the structure of the ball bearing linear guideway 10 can equally provide load capacities in downward, upward and lateral directions. However, this design is still unable to provide a rated static load capacity which is great enough to satisfy the machines which require higher load capacities in downward, upward and lateral directions.
FIG. 2 shows a ball bearing linear guideway 20 disclosed in U.S. Pat. No. 6,132,093, which is a conventional technology for increasing the rated static load capacity in the downward and upward directions. The ball bearing linear guideway 10 generally comprises: a slider 21 slidably mounted on a rail 22, and four rows of balls 23 disposed between the slider 21 and the rail 22. Two rows of balls 23 are disposed at the top of the rail 22 to increase the rated static load capacity in the downward direction, and another two rows of balls 23 are disposed at two sides of the rail 22 to increase the rated static load capacity in the upward direction by contact points. However, by looking at the arrangements of the four rows of balls 23, we can see that the two rows of balls 23 at the top of the rail 22 are only capable of bearing the load in the downward direction, but totally unable to bear any load in the upward and lateral directions, while the two rows of balls 23 at two sides of the rail are able to bear the load only in the lateral direction, but totally unable to bear the load in the downward direction. In general, the load capacity cannot be considerably improved in all of the downward, upward and lateral directions. The load capacity might be improved in the downward direction but not in the upward and lateral direction, as a result, the load capacity in general is still not sufficient to enable the ball bearing linear guideway to be applicable to most machines. Furthermore, due to the fact that both the top surface and lateral surfaces of the rail 22 are provided with rolling grooves for reception of the balls 23, the rail 22 must be subjected to a top grinding process and a lateral grinding process, which substantially increases manufacturing cost and reduces manufacturing efficiency. Besides, the two grinding processes have different grinding datum, which may result in position error between the rolling grooves of the top surface and the lateral surfaces, and reduces the accuracy of the ball bearing guideway.
However, increasing the size of the ball bearing linear guideway may increase the load capacity in all of the downward, upward and lateral directions, but the increased size makes the ball bearing linear guideway inapplicable to most machines.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.


A Multi-chip semiconductor package having the thinnest structure. The package includes a chip set including a first bare chip and a second bare chip which are connected to each other by solder interposed therebetween and a plurality of TAB tapes each having an inner lead and an outer lead, the first bare chip and the second bare chip being provided with a plurality of solder bumps at opposite sides of surfaces thereof facing to each other, each of the inner leads being bonded between each corresponding the solder bump of the first bare chip and each corresponding the solder bump of the second bare chip, and a lead frame bonded to the outer leads of the TAB tapes. The chip set of the multi-chip semiconductor package may be connected to other chip set so that the package has four bare chips. Therefore, the thinnest multi-chip semiconductor package can be achieved and an integration of the package is improved. Also, a chip set is formed by fixing lead frames between two bare chips, to render the chip sets stably and firmly stacked and the pads of each bare chip disposed at desired position.

1. Field of the Invention
The present invention relates to a multi-chip semiconductor package which has an improved integration by superposing several semiconductor chips, and more particularly to a multi-chip semiconductor package which is capable of having the thinnest structure by using a TAB technology (Tape Automated Bonding Technology) and a C-4 bonding technology.
2. Description of the Prior Art
Recently, a semiconductor package tends to be miniaturized, that is, be light and thin, while a bare chip gradually becomes larger in size so that an area or a volume ratio of the bare chip to an overall semiconductor package increases. Accordingly, a technology for manufacturing a semiconductor package is gradually converted from the conventional plastic packaging technology in which a chip is placed on a paddle to LOC (Lead-On-Chip) technology in which leads are placed on a chip. Also, a semiconductor package is usually equipped with one bare chip, but it is well known that a multi-chip semiconductor package is manufactured by superposing several chips in order to form a piggy-bag type package or by superposing several chips inside a semiconductor package (disclosed in the Nikkei Micro Devices, April, 1991).
Referring to FIG. 1, there is shown a perspective view representing a typical embodiment of a conventional multi-chip semiconductor package which has the piggy-big type. As shown in FIG. 1, a plurality of semiconductor packages 2 are superposed on the lowermost semiconductor package 1 and outer leads 2a attached to upper semiconductor packages 2 are bonded to outer leads 1a attached to the lowermost semiconductor package 1 in a conventional manner so that the outer leads 1a and 2a are electrically connected to the another. The outer leads 1a of the lowermost semiconductor package 1 are outwardly formed into a SOP (Small Outline Package) type and fitted in a memory module or a board level. Therefore, the conventional piggy-bag type of semiconductor package has an improved integration 3 dimensionally.
However, since the conventional semiconductor package is constructed such that the semiconductor packages 1 and 2 each of which was made separately are superposed, the conventional semiconductor package has disadvantage in that each semiconductor package increases in a thickness by an increased wire loop height owing to a wire bonding and a mold thickness of encapsulation epoxy resin, thereby causing the thickness of the whole semiconductor packages to inevitably increase.
On the other hand, referring to FIG. 2, there is shown a cross sectional view representing a construction of a conventional multi-chip semiconductor package in which upper and lower bare chips are laterally arranged in parallel to each other in a single semiconductor package.
With reference to FIG. 2, the manufacturing process of the multi-chip semiconductor package is described as follows. First, two bare chips 3 and 4 are connected to each other. Inner leads to TAB tapes 5 and 6 are bonded to bumps 8 provided at pad portions of the bare chips 3 and 4 by the TAB technology. Outer leads of the TAB tapes 5 and 6 are bonded to lead frames 9 and 9', respectively. Finally, a mold portion 10 enveloping the resulting chip assembly is formed by applying an epoxy resin. Accordingly, a single semiconductor package has two bare chips 3 and 4 therein, thereby improving the integration of the elements and miniaturizing the package, that is, allowing the package to be light and to be thin.
In addition, referring to FIG. 3, there is shown a cross sectional view representing another embodiment of conventional multi-chip semiconductor packages in which four bare chips 11, 12, 11a and 12a are embedded therein.
In a similar manner to that described in FIG. 2, the multi-chip semiconductor package shown in FIG. 3, is manufactured as follows. In the upper half part of the multi-chip semiconductor package, the upper and lower bare chips 11 and 12 are connected to each other. Inner leads of TAB tapes 15 and 16 are bonded to bumps 13 and 14 of the chips 11 and 12, respectively. The bumps 13 and 14 are provided at opposite ends of upper and lower surfaces of the chips 11 and 12, respectively. Outer leads of the TAB tapes 15 and 16 are bonded to lead frames 17 and 17', respectively. At the same time, in the lower half part of the multi-chip semiconductor package, an upper bare chip 11a and a lower bare chip 12a are connected to each other. Inner leads of TAB tapes 20 and 21 are bonded to bumps 18 and 19 provided at opposite ends of upper and lower surfaces of the upper and lower bare chips 11a and 12a. Outer leads of the TAB tapes 20 and 21 are bonded to the lead frames 17 and 17' , respectively. Finally, a mold portion 22 enveloping the resulting chip assembly is formed as applying the encapsulation epoxy resin. Accordingly, a single semiconductor package has four bare chips 11, 12, 11a and 12a therein, thereby more improving its integration and more miniaturizing the package than that shown in FIG. 2.
However, in the above-mentioned multi-chip semiconductor packages shown in FIG. 2 and FIG. 3, since the inner leads of the TAB tapes 6 and 15, 16, 20, 21 are bonded to the bumps 7, 8 and 13, 14, 18, 19 provided at upper and lower surfaces of the bare chips 3, 4 and 11, 12, 11a, 12a, the heights H and H', the one between the upper TAB tape 5 and the lower TAB tape 6 and the other between the upper TAB tape 15 and the lower TAB tape 21, increase, thereby causing a thickness of the whole semiconductor packages to increase.
Also, since the numbers of the TAB tapes 5, 6 and 15, 16, 20, 21 increase, a manufacturing cost of the multi-chip semiconductor package increases and a complex process is obliged to be required for manufacturing the package.
In addition, since each inner lead bond (ILB) between the bare chips 3, 4, 11, 12, 11a, and 12a and the TAB tapes 5, 6, 15, 16, 20, and 21 is formed at an outer surface of the bare chips 3, 4, 11, 12, 11a, 12a, the multi-chip semiconductor packages are not proper for the LOC technology. Due to relatively short lengths of the TAB tapes 5, 6, 15 and 16, a bonding process of the inner lead bonds is complex and a handling thereof is not easy.


A receiver and a composite component for preventing noise produced by sneaking of a local oscillation signal. An FM receiver comprises a high-frequency amplifier circuit 11, a mixing circuit 12, a local oscillator 13, intermediate-frequency filters 14 and 16, an intermediate-frequency amplifier circuit 15, a limit circuit 17, an FM detection circuit 18, and a stereo demodulation circuit 19. The mixing circuit 12 and the local oscillator 13 constitute a one-chip composite component 30 integrally formed on a semiconductor substrate. The frequency of the local oscillation signal is set so that the difference of frequency between the local oscillation signal and a modulated wave signal may be smaller than the occupied bandwidth of the modulated wave signal.

A general receiver adopting a super-heterodyne method converts a frequency by using a mixing circuit after amplifying a modulated wave signal received via an antenna at a high frequency, and demodulates it after converting it into an intermediate-frequency signal having a predetermined frequency. For instance, an FM receiver in Japan is using a local oscillation signal deviated from a carrier frequency of the modulated wave signal by 10.7 MHz, where FM detection and stereo demodulation processes are performed to the intermediate-frequency signal of 10.7 MHz.
In particular, in some data communication fields, a technique called a direct conversion method using the local oscillation signal almost equal to the modulated wave signal, and such a receiver demodulates the intermediate-frequency signal of a low frequency.
Incidentally, the above-mentioned receiver in the past has a problem that, if a signal leaked via printed wiring of a local oscillator for generating the local oscillation signal sneaks on an input side of the modulated wave signal, it becomes noise and appears in the intermediate-frequency signal. In particular, in the case of the receiver adopting the direct conversion method, the frequencies of the modulated wave signal and local oscillation signal are close, and so the same frequency component as the local oscillation signal is superimposed as noise on the modulated wave signal. Furthermore, in the case where this noise component is included in a frequency bandwidth of the modulated wave signal, the noise component cannot be eliminated from the intermediate-frequency signal so that quality of a receiver signal deteriorates.

Receiver and composite component having local oscillator components and mixing circuit integrally formed on semiconductor substrate


A rocket engine chamber has a back structure and a heat exchanger structure located radially inwardly of the back structure. The heat exchanger structure has a plurality of integrally formed cooling passageways with adjacent ones of the passageways having a common sidewall structure. Each passageway has a top section which forms the wall that contacts the hot gases. The top section is formed by a wall structure having an inner and outer surface formed by an arc of a circle and a substantially constant wall thickness.

The present invention relates to liquid rocket engines and specifically re-usable rocket engines which are operated many times.
Most liquid rocket engines have been expendable. That is, when the engine design reaches operational maturity, each production engine is operated probably only twice—once in a ground test to verify that the engine works and a second time when it is flown and expended. The only re-usable liquid rocket engine in operation today is the Space Shuttle Main Engine.
Several U.S. liquid rocket engine combustion chambers are made using tubes. The tubes are bent into the shape of the rocket chamber/nozzle, which is similar to a slice through the familiar "bell" shape. Then the tubes are fixtured in an axisymmetric array and joined together to form the complete chamber/nozzle. To complete the chamber/nozzle, external structure must be added to strengthen the joined tubes, and manifolds must be added at each end of the array of tubes for coolant inlet and discharge. The advantage of a tube is that it is an excellent pressure vessel. The disadvantages however are numerous. Each individual tube must be formed to size and shape to conform to design specifications. Also, it takes a large number to make a complete chamber, in many cases 200 or more. This makes the tubes, essentially the chamber/nozzle raw material, a large cost item. Next the tubes and manifolds must be joined in place without leaks. This is very difficult to do without fault, and re-work is often required, further increasing chamber/nozzle cost.
Some liquid rocket engines build the chamber/nozzle in a different way. This method is known as "milled channel with close-out". First, a "bell" is made beginning with flat sheet and rolling/welding or some similar process. Then coolant channels are machined into the bell shaped structure. A second bell which fits over the first one is then made. The second bell is then joined to the first to create the channel close-outs. In similarity with the tubular construction described above, structural stiffeners and inlet/discharge manifolds are then joined in place to complete the chamber. Advantages are that this method can be made to work with fewer parts than with tubes. Disadvantages include the operations used to join different parts. Also, the resulting channel structure is rectangular, with one of the flat walls facing the combustion chamber. The rectangular passage, and especially the flat side of the passage facing the combustion chamber, undergoes plastic deformation while operating. This results in actual thinning of the wall which does not recover original thickness on shutdown. Thinning increases with subsequent use. This phenomena has been termed "ratcheting" by the structures analysts. Overall result is a life-limited structure, with life nominally less than 100 cycles. Tubular chamber construction undergoes similar operational structural deformation, however, not to the same degree as with the milled channel construction, primarily due to the tube acting as an efficient pressure vessel.
An advanced method has been developed to make liquid rocket chambers and nozzles. Specifically, the method is known as vacuum plasma spray and is exemplified by U.S. Pat. No. 5,249,357. This method is equivalent to the milled channel method described above with two primary differences: (1) the "bell" is sprayed on a bell-shaped mandrel beginning with powder raw material and using a high-temperature inert gas stream; and (2) the channel close-outs are similarly sprayed. At this point in time, the method has been used to make only flat wall chambers. These have rectangular cooling channels with one of the flat walls facing the combustion chamber. Fabrication costs are significantly lower than either tubular construction or milled channel with joined close-out, due primarily to using the spray process to create a near net shape, integral (one-piece) chamber/nozzle. The disadvantage of this method is the flat wall facing the combustion chamber and its life-limiting characteristics of deflection and thinning at operation pressure and temperature.


A DQPSK receiver extracts first and second phase modulation components from an input optical signal, and respectively converts the extracted components into the first and second data signals. The DQPSK receiver extracts a clock signal from one of the data signals, and produces an inverted clock signal by inverting the extracted clock signal. Then, the DQPSK receiver latches the first data signal by using the extracted clock signal or the inverted clock signal, and latches the second data signal by using the extracted clock signal.

1. Field of the Invention
The present invention relates to an optical receiver device for receiving optical signals modulated using Differential Quadrature Phase Shift Keying (DQPSK) in an optical transmission system.
2. Description of the Related Art
In recent years, an optical transmission system which employs the DQPSK modulation is proposed as one of solutions for expanding bandwidth in an optical communication network (for example, see Patent Document 1 below). In this modulation method, two bits of information are transmitted in one symbol, thereby, a bit rate of 40 Gb/s at a modulation rate of 20 Gbaud/s is realized. In this optical transmission system, an optical. transmitter device modulates optical carrier waves using the DQPSK and transmits them as the optical signals, and an optical receiver device demodulates the received optical signals and extracts the data.
Patent Document 1
Publication in Japan of translation of PCT International Patent Application: No. 2004-516743
FIG. 1A shows a configuration of a DQPSK receiver used in a conventional optical receiver device. This DQPSK receiver comprises an optical splitter 11, delay interferometers 12-1 and 12-2, photodiodes 13-1, 13-2, 13-3 and 13-4, transimpedance amplifiers (TIA) 14-1 and 14-2, limiting amplifiers (LIA) 15-1 and 15-2, a clock recovery circuit (CR) 16, decision circuits (DEC) 17-1 and 17-2 and a 2-to-1 multiplexer (MUX) 18.
Two optical signals split by the optical splitter 11 are respectively input into the delay interferometers 12-1 and 12-2. In these optical signals, as relative phase values with respect to the previous signal by one symbol, four phases of π/4, 3π/4, −π/4 and −3π/4 are used.
The delay interferometer 12-1 splits the input optical signal into two signals, delays one optical signal by one symbol using a delay generator 21-1, gives a phase shift of π/4 to the other optical signal using a phase shifter 22. Then, the delay interferometer 12-1 extracts phase modulation components by causing the two optical signals from the delay generator 21-1 and the phase shifter 22 to interfere with each other, and outputs the extracted phase modulation components to the photodiodes 13-1 and 13-2.
The delay interferometer 12-2 splits the input optical signal into two signals, delays one optical signal by one symbol using a delay generator 21-2, gives a phase shift of −π/4 to the other optical signal using a phase shifter 23. Then, the delay interferometer 12-2 extracts phase modulation components by causing the two optical signals from the delay generator 21-2 and the phase shifter 23 to interfere with each other, and outputs the extracted phase modulation components to the photodiodes 13-3 and 13-4.
In the above manner, the two phase modulation components which are orthogonal to each other are extracted from the received optical signal by the delay interferometers 12-1 and 12-2, and the extracted phase modulation components are converted into variation of light intensity to be output.
The photodiodes 13-1 and 13-2 forms balanced photodiodes to convert the optical signals output from the delay interferometer 12-1 into an electric current by the photoelectric conversion and to output the electric current. The transimpedance amplifier 14-1 conducts a current-voltage conversion. The amplifier 15-1 amplifies the converted electric signal and outputs the amplified signal to the decision circuit 17-1 as the first data signal.
Similarly, the photodiodes 13-3 and 13-4 convert the optical signals output from the delay interferometer 12-2 into an electric current. The transimpedance amplifier 14-2 conducts a current-voltage conversion. The amplifier 15-2 amplifies the electric signal and outputs the amplified signal to the decision circuit 17-2 as the second data signal. In this manner, the received optical signal is detected and the data is extracted from the input signal.
The clock recovery circuit 16 extracts a clock signal from the first data signal input to the decision circuit 17-1, and distributes the signal to the decision circuits 17-1 and 17-2. The decision circuits 17-1 and 17-2 are configured by using for example D flip-flop circuits, respectively latches the first data signal and the second data signal in accordance with the extracted clock signals, and outputs the signals to the multiplexer 18. The multiplexer 18 multiplexes the two data signals from the decision circuits 17-1 and 17-2, and transfers the multiplexed signal to a deserializer (not shown) at a later stage.
For example, when quadrature signal Q and in-phase signal I as shown in FIG. 1B are respectively obtained as the first data signal and the second data signal, the multiplexer 18 multiplexes these signals in order to produce the original data string "ABCDEF . . . ".
When the in-phase signal I and the quadrature signal Q as shown in FIG. 1C are respectively obtained as the first data signal and the second data signal, the multiplexer 18 multiplexes these signals and produces a data string "BADCFE . . . ". However, the produced data string is different from the original data string "ABCDEF . . . ", accordingly, a bit swap function have to be provided in the multiplexer 18 or in a circuit (framer or the like) at a later stage for swapping adjacent data. In this case, the invention described in Japan Patent Application No. 2005-206467 can be utilized, which is a prior application.
FIG. 1D is a timing chart showing an example of input and output signals of the decision circuits 17-1 and 17-2. In this example, the signals input to the decision circuits 17-1 and 17-2 are latched by the rising edges of the clock signal and the output data signals are produced.
However, the above described conventional DQPSK receiver has problems as below.
As shown in FIG. 1A, the conventional DQPSK receiver employs a configuration in which two decision circuits 17-1 and 17-2 operates in accordance with the clock signal extracted by the single clock recovery circuit 16. The timing chart shown in FIG. 1D shows no differential delay between the data signals input to the decision circuits 17-1 and 17-2, however, a differential delay of ΔT actually occurs between the two input data signals as shown in FIG. 1E.
As shown in FIG. 1F, this differential delay of ΔT is equivalent to a difference of |Ta−Tb| between the delay time Ta from the input terminal of the optical splitter 11 to the input terminal of the decision circuit 17-1 and the delay time Tb from the input terminal of the optical splitter 11 to the input terminal of the decision circuit 17-2. In the DQPSK receiver, the differential delay of ΔT is required to be sufficiently smaller than the input phase margin of the multiplexer 18.
The electric circuit and the delay interferometers 12-1 and 12-2 made of PLCs (Planar Lightwave Circuits) in the DQPSK receiver can be manufactured such that a physical length difference is equal to or smaller than 1 mm to 2 mm (about 10 ps). Accordingly, the differential delay there is equal to or smaller than the input phase margin (25 ps to 35 ps) of the multiplexer 18 in the case of employing the time slot of 20 Gb/s (50 ps).
However, in the case where there is a fiber interface between the optical splitter 11 and the delay interferometers 12-1/12-2 such as the case where the optical splitter 11 is provided as an external device, it is difficult to fabricate fibers exactly in the equal length if fusion splice is taken into consideration, which results in the difference of about 1 cm. The difference of 1 cm is equivalent to the differential delay of about 50 ps, and to the shift by one bit at the transmission rate of 20 Gb/s, which results in a serious problem and requires an initial adjustment.
In this case, almost the entirety of the differential delay ΔT consists of the difference between the delay time Ta1 from the input terminal of the optical splitter 11 to the input terminal of the delay interferometer 12-1 and the delay time Tb1 from the input terminal of the optical splitter 11 to the input terminal of the delay interferometer 12-2, i.e., |Ta1−Tb1|.
Further, the differential delay between the data signals output from the decision circuits 17-1 and 17-2 which are to be input to the multiplexer 18 has to be suppressed to a sufficiently small value such as about 10 ps to 15 ps compared to the phase margin.
In the invention described in Japan Patent Application No. 2005-245071 employs the configuration in which a delay amount of the data signals is adjusted using a variable delay circuit. However, manufacture of the conventional variable delay circuit which is commonly used supposes the use of CMOS (Complementary Metal Oxide Semiconductor), and the operation at 20 Gb/s cannot be realized by the current circuit technology. It is also thought that manufacture of the circuit having the same function with Silicon-Germanium is not practical in view of scale of the circuit and the electric power consumption.


A block is produced by juxtaposition and joining of at least one plate made of tool steel and of at least one plate made from mild steel. The block is hot rolled and then it is cooled to a temperature below 200.degree. C. The rolled block is tempered at a temperature above 450.degree. C. after cooling. The clad sheet obtained includes a layer made of tool steel having a tempered martensitic structure and containing primary carbides and a fine dispersion of secondary carbides.

In mining, quarrying, civil engineering or other sectors of industry, it is known to use clad sheets having an abrasion-resistant layer, made of tool steel, and an easily weldable layer made of mild steel, in order to produce equipment such as hopper casings, dozer blades or other devices subjected to abrasion.
These clad sheets are generally obtained by rolling and are used in the as-rolled cooled state. These clad sheets have the maximum hardness that it is possible to obtain and therefore a high abrasion resistance. But it is desirable to improve this abrasion resistance further. Moreover, during the cooling, after rolling, the clad sheets form a bimetal and distort. It is necessary to planish them. On account of the great hardness of the layer made of tool steel, this operation is difficult and generates large residual stresses in the clad sheets, stresses which are annoying during implementation and in use.

Process for manufacturing a clad sheet which includes an abrasion-resistant layer made of tool steel, and clad sheet obtained


A system and method for recovering application authentication with an application server by using an exponential back-off procedure via push notifications is discussed herein. The system allows for authentication of a user account after network outages or service disruptions without traffic overload during recovery. A user equipment (UE) receives a failed registration notification after a failed registration attempt of the user account with an application server associated with the application. A push notification includes an instruction that causes the application to switch from an inactive state to a temporary active state. The push notification is sent from a push notification service in response to a push request from a notification server based on a recovery request from the UE due to the failed registration notification. While the application is in the temporary active state, the instruction further causes the application to request registration with the application server.

Some mobile applications enable persistent login for a user account. Therefore, an application user does not need to re-authenticate the user account to use a service provided by the application. When application servers become inaccessible, such as due to a network outage or service disruption, the application has to recover access to the application server. The user account then needs to be re-authenticated.
Recovering authentication of the user account requires user interaction or user-initiated access requests. The application has to be activated by being brought to the foreground by the user. Once in the foreground, the application can send a registration request to the application server via a user equipment (UE) on which the application is installed. The registration request can be initiated by the application or by the user once the application becomes active. Before attempting re-registration, the user account can remain logged in or can logout and then login again. The re-authentication and re-registration processes are both time-consuming and frustrating to a user and decrease the quality of users' experience with the application and with their telecommunications network.
Furthermore, as more user accounts, applications, or both send registration requests, the network can become overloaded due an increase in volume of traffic. The increased volume of traffic can degrade network performance leading to slower network speeds, dropped services, or the like.
The state of the art would benefit from a system that more efficiently requests application server registration.

Mobile client recovery using push notifications to execute exponential back-off procedure


Disclosed is an embodiment of a dual seal arrangement for the high-speed shaft of a supercharger with a centrifugal compressor and a mechanical speed step-down transmission to the shaft. A ring located about the shaft splits the rotational speed of the shaft between two seals, so that each seal spins at a speed of roughly half the speed of the shaft. The arrangement can also be used to split the shaft speed between two bearings in the same manner. The high-speed shaft may also have a turbine attached, to form a driven turbocharger.

Superchargers are commonly used on engines to provide pressurized intake air to increase power and torque of the engine. One class of supercharger has a high-speed centrifugal compressor that is mechanically driven by a speed step-down transmission. This type of supercharger can have the compressor, and can also include a turbine on a common shaft with the compressor to form a driven turbocharger.


A continuously variable ratio transmission including a planetary gear set having a sun gear, a ring gear, and a planet carrier having at least two planet gears carried thereon, a control element including a servogenerator capable of generating electric power, and at least one auxillary field coil adapted to be operatively connected to an output means to influence a power output level and AC power frequency of the output means, the at least one auxillary field coil being powered by the servogenerator and constituting a load to the servogenerator, the speed of the servogenerator being capable of being controlled by the load; and a means for controlling an electrical current to the at least one auxiliary field coil form the servogenerator; where the servogenerator is capable of being driven to produce electrical power by a rotation of one of the sun gear, the ring gear, and the planet carrier.

1. Field of the Invention
The present invention relates to continuously variable ratio transmissions (CVT) employing planetary gear sets, and a system in which the CVT is integrated with the input driver and output driven systems through a regenerative/control subsystem. The present also relates to varying forms of the planetary gear set used in the CVT.
2. Description of Related Art
Planetary gear sets are well known in the art as a form of a mechanical transmission device. The planetary gear set operates with three rotary elements rotating around at least three different axles. The three rotary elements are a sun gear, a ring gear, and a planet gear/gears carried on a planet carrier. The three elements are meshed together via gear teeth, for example.
FIG. 1, shows, schematically, an exploded view of a basic planetary gear set 10. The ring gear 12 has a cavity 14 into which the planet gears 16 and sun gear 18 are positioned. Planet gears 16, carried on planet carrier 20, mesh with an inner surface of the ring gear 12. Sun gear 18 meshes with the planet gears 16 at an inner extent. Sun gear 18 has an axle 22 extending through planet carrier 20, and a control gear 24 of planet carrier 20 may be driven at varying rates or locked in place, to provide the variation in the transmission ratio between the sun gear axle 22 and the ring gear axle 26.
FIGS. 2 A–C illustrate variants on the basic planetary gear set shown in FIG. 1, all of which can be suitable for use in a CVT. FIG. 2A illustrates a planetary gear set having multiple meshed planet gears. FIG. 2B illustrates planetary gear set employing compound planet gears, meaning that the planet gears at either end of the planet carrier are each actually made up of two gears of different diameters, the gears of one diameter engaging the ring gear, and the gears of the other diameter engaging the sun gear. FIG. 2C is a simple differential having at least three rotary elements that are accessible from coupling with axles outside the transmission system. One of the rotary elements can be subjected to external control to vary the transmission ratio of the other two rotary elements axles.
In most current industrial applications, one element or axle, for example, the ring gear/axle, work as the input axle. A second element or axle, for example, the sun gear/axle, works as the output axle. The third element and axle, e.g., the planet carrier with its planet gears, in this example, has a rotation control device such as a brake or clutch, to cause the other two elements to rotate at a fixed ratio of rotary speeds. The roles of the three gear/axle elements may be interchanged, and the foregoing is simply one example. Planetary gear systems have inherently high efficiency when used in transmission applications of this type.
U.S. Pat. No. 4,973,295, issued on Nov. 27, 1990, to the present inventor, discloses a stepless (continuously) variable ratio transmission (CVT) in which all three rotary elements are capable of rotating, and the rotation of the axle that is not the input or output axle is variably controlled to vary the transmission ratio between the other two elements. The disclosure in this patent is hereby expressly incorporated by reference.
In one of the embodiments disclosed in the '295 patent, the planet carrier is operated to control the transmission ratio between the sun gear/axle and ring gear/axle, by coupling the planet carrier to a worm gear which is driven at a desired speed (or held stationary, at one extreme) by the worm which in turn is driven by a motor such as a stepping motor or servomotor. The motor is controlled by a computer which monitors the speed of the input and output axles, to control the motor to drive the worm gear at a speed which will yield the desired rotary relationship (ratio) between the input and output axles.
Planetary gear systems and variations thereon are three (or more) terminal mechanical systems in which a larger flow of energy between the input and output is controlled by the lower energy control terminal. The ratio between the larger energy flow under control and the energy needed to provide such control is called control gain. For example, if a 1 hp servomotor is needed to control a CVT connecting between a motor and a water pump both with nominal power of 100 hp, then the control gain of the system is roughly around 100.
The range of CVT transmission ratios is the ratio between the highest and lowest transmission ratios at which a CVT is designed to work. For example, if a CVT works between 3:1 (ratio=input RPM:output RPM, therefore higher reduction has higher ratio value) and 1:1, then the ratio range is 3. If, on the other hand, a CVT works between 3:1 and 1:3 will have a ratio range of 9. The latter is defined to have a wider range (9) than the former (3).
The overall efficiency is important for evaluating a mechanical transmission system. A transmission needs energy to overcome friction, for energy conversion, and for accessories that are necessary for the functioning of the transmission system. The ratio between the energy available for output and the total energy input is the overall efficiency of the system.
In the CVT disclosed in the '295 patent, the progression angle of the worm—worm gear pair was chosen at the "critical angle" so the worm—worm gear is in between the self-locking and non-self-locking condition. In other words, the power needed to drive and control the rotation speed of the step-/servo-motor is minimized. Also, part of the energy needed to overcome the friction involved in the worm—worm gear is from the main energy source of the input axle.
When a CVT system, such as the one disclosed in the '295 patent, works within a ratio range, e.g., for reduction, the minimum reduction ratio is achieved by mechanical geometry design of the gear set while assuming the control axle is in standstill condition. The control axle has to spin faster when higher reduction ratio is required. Despite the mechanical gear system's inherent high efficiency, the overall efficiency will be the highest when the control axle is not moving, because the system does not need to overcome the friction involved in the worm system, nor is any energy needed to rotate the servomotor to drive the worm. When the control axle is moving faster at the upper range of the variable ratios, the overall efficiency will be lowered.
Thus, while a CVT of such design works in a wide range of transmission ratios, at the higher transmission ratio side of the range, the overall efficiency will be at the lowest.
In addition to efficiency concerns when operating at the higher end of transmission ratios, certain applications for which a CVT might be considered have requirement for low noise and the like, for which gear sets operating with meshed gear teeth may not be suitable.
Further, applications may exist in which the efficiency and control gain desired from a CVT can not be adequately met by a single planetary gear set.
It is therefore a principal object of the present invention to provide CVT system that improves upon the overall efficiency of the system in operation, particularly at the upper end of transmission ratios.
It is a further principal object of the present invention to provide low-noise CVT designs for use in applications requiring low noise operating conditions.
It is yet a further principal object of the present invention to provide a CVT systems having improved control gain and efficiency characteristics.

Continuously variable ratio transmission


In a multi-blade centrifugal fan including an impeller (7) rotatably disposed in a casing and composed of a disc-shaped hub (8), a plurality of blades (9), and an annular shroud (10), the blades (9) are curved in a concave shape on a pressure side in a cross-section perpendicular to a rotating shaft of the impeller (7) and have a curved shape that is backward-swept near a leading edge (9C) thereof and that is forward-swept near a trailing edge (9D) thereof, the inner diameter of the cascade of blades (9) increases gradually from the hub (8) toward the shroud (10), and the diameter of a maximum-curvature position (9B) where the curvature of the curved shape is maximized increases gradually from the hub (8) toward the shroud (10).

Multi-blade centrifugal fans, called sirocco fans, include an impeller composed of a disc-shaped hub whose center is convex on the intake side, a plurality of blades (also called blades, vanes, or the like) arranged radially on the periphery of the hub, and an annular shroud disposed at the opposite ends of the blades from the hub, and a scroll-shaped fan casing in which the impeller is rotatably supported. For a typical multi-blade centrifugal fan, the shape of the blades in a cross-section perpendicular to the rotating shaft of the impeller is substantially uniform in the axial direction, that is, two-dimensional. This is so that the impeller can be formed by plastic molding at relatively low cost.
The multi-blade centrifugal fan deflects a flow taken in in the direction along the rotating shaft to a centrifugal direction perpendicular to the rotating shaft through the impeller and blows it from the periphery of the impeller into the casing. This causes a problem in that it is difficult to fully utilize the entirety of the blades because the flow is insufficiently deflected on the shroud side, which is closer to an intake port, and also less easily reaches the vicinity of the hub, with the result that the flow concentrates at a position slightly closer to the hub than the center of the blades in the spanwise direction. In addition, because the blades have a uniform cross-sectional shape despite the flow state varying in the direction along the rotating shaft, the blade shape does not match the flow, which results in decreased efficiency and airflow disturbance, thus leading to increased fan input power and noise.
Various proposals have thus been made for improved fan efficiency and reduced noise. PTL 1 discloses a multi-blade centrifugal fan including blades curved in a concave shape on the pressure side and satisfying β2<β3, where β2 is a middle angle between a tangent to a circle whose radius is a line segment joining the middle point in the middle portion between the inner and outer ends of each blade and the center of the fan and the surface of the blade at the middle point, and β3 is an exit angle between a tangent to a circle whose radius is a line segment joining the exit point of the outer end of each blade and the center of the fan and the blade surface at the exit point, which is intended to relatively increase the static pressure component for reduced noise and increased fan efficiency.
In addition, PTL 2 discloses a multi-blade centrifugal fan including blades having a tapered portion formed at least at one end of an inner edge (leading edge) thereof in the axial direction such that the inner diameter thereof increases from the other end to the one end in the axial direction, the tapered portion being located forward in the rotational direction and having an entrance angle of 55° to 76° for increased work of the impeller, improved efficiency, and reduced noise. In addition, PTL 3 discloses a multi-blade centrifugal fan including blades curved in a concave shape on the pressure side such that they are backward-swept near the leading edge thereof and are forward-swept near the trailing edge thereof, wherein the sum of an entrance angle β1 and an angle β′2 is set to less than 80° to reduce the noise level without a decrease in the volume of air, where β1 is the entrance angle of the blades, β2 is the exit angle of the blades, and β′2 is the difference obtained by subtracting the exit angle β2 from an angle of 180°.

Multi-blade centrifugal fan and air conditioner using the same