A frictional engagement element (32) that disconnects power between an engine (1) and a drive wheel (7) in a vehicle, and a control unit (11, 12) that controls a transmission ratio of a continuously variable transmission (4) and the frictional engagement element (32), are provided. When the transmission ratio is not a maximum transmission ratio at a vehicle stop when a vehicle speed is 0, the control unit (11, 12) operates the transmission ratio to the maximum transmission ratio while controlling the frictional engagement element (32) into a slip state. Further, at this time, when a road is an upward slope, the control unit (11, 12) sets an engagement pressure of the frictional engagement element (32) and an engine torque according to the road slope, prevents slide-down of the vehicle.

In a vehicle having a continuously variable transmission, during deceleration before vehicle stop, by operating a transmission ratio up to a maximum transmission ratio by the time that the vehicle stops, starting performance at a subsequent re-start of the vehicle is ensured. However, in a case of the deceleration by hard braking during vehicle travelling, since a time required for the vehicle stop is short, it is not possible to operate the transmission ratio up to the maximum transmission ratio by the time that the vehicle stops. Further, if a wheel locks during the deceleration, even the operation to change the transmission ratio is not possible. Also after the vehicle stop, it is not possible to operate the transmission ratio as a matter of course.
Patent Document 1 discloses that in a vehicle provided with an auxiliary transmission having as a power transmission cut-off unit a clutch or a brake between the continuously variable transmission and a drive wheel, when the hard braking of the vehicle is detected, by disengaging the clutch or the brake of the auxiliary transmission and bringing power transmission between the auxiliary transmission and the drive wheel into a power transmission cut-off state, the changing operation of the transmission ratio becomes possible, then the transmission ratio is operated up to the maximum transmission ratio by the time that the vehicle re-starts afterwards. A technique of ensuring the starting performance, devised in this manner, is disclosed in the Patent Document 1.
Here, in the case of the technique of the Patent Document 1, when starting a control of the changing-operation of the transmission ratio to the maximum transmission ratio side with the power transmission brought in the cut-off state, as long as a throttle valve opening degree is 0 (zero) (a throttle valve is in a fully closed state), this control is performed until the transmission ratio reaches the maximum transmission ratio. Thus, during the carrying out of the transmission ratio control in this power transmission cut-off state, the power is not transmitted to the drive wheel. Therefore, if this control is performed when the vehicle stops on an upward slope (an uphill road), there is a risk that slide-down (or slip-down) of the vehicle will occur.
Further, in the case of the technique of the Patent Document 1, the power transmission cut-off is performed by pressure exhaust by exhausting working fluid from a working fluid supply oil passage that leads to the clutch and the brake. Thus, even when the transmission ratio control is completed and the power transmission is changed from the power transmission cut-off state to a power transmission allowable state, a time lag required for an engagement of the clutch or the brake occurs. For this reason, depending on a timing of the re-start, there is a possibility that a power transmission lag will occur. In order to reduce this power transmission lag, setting a line pressure to be high is effective. In this case, however, engagement shock of the clutch or the brake occurs, which is undesirable.
The present invention was made in view of the above technical problem. An object of the present invention is to provide a control device for the continuously variable transmission, which is capable of changing-operation of the transmission ratio of the continuously variable transmission up to the maximum transmission ratio (i.e. to a Lowest state) at the hard braking etc. of the vehicle even when the vehicle stops on the upward slope without the occurrence of the slide-down of the vehicle, and capable of suppressing the occurrence of the power transmission lag at the re-start without setting the line pressure to be high.

Control device for continuously variable transmission


A detachable cover for a motorcycle cowling that can be easily switched with a service part is described. The cover includes a cover front edge section that is formed so as to form a generally continuous surface with at least a portion of an outer periphery edge section of a head light, and a cover rear section that is removably attachable to the cowling and that extends to the rear from the cover front edge section when attached to the cowling. A motorcycle that easily allows external appearance to be changed to satisfy a user's requirements is also described.

Motorcycles are known that, in order to improve external appearance and bearing in mind the need to improve wind shielding effect when running, the front side of a steering handle is covered by a cowling. This type of cowling generally includes a front wall that covers an outer periphery section of a head light, and left and right side walls that extend continuously to the rear from the front wall (for an example, refer to JP-A-2005-35526).
However, in the case of the above-described known cowling for a motorcycle, a design that is thought optimal for each type of motorcycle is used. Thus, it is generally the case that the structure of the cowling cannot be easily switched. Recently, there has been demand in the commercial market for use of structures that allow switching to a cowling that has a design that matches the preferences of the user. However, cowlings are a component that are comparatively large and expensive. Thus, if the cowling is switched as is, considerable expense and a troublesome switching operation are required. As a result, switching of the cowling is not practical, and it has not been possible to satisfy a broad range of users' requirements.


The present invention relates to a display comprising at least one substrate and at least one electronically modulated imaging layer and at least one electrically conductive layer, wherein the electronically modulated imaging layer comprises a self-assembled, close-packed, ordered monolayer of domains of electrically modulated material in a water insoluble, hydrophobic polymer matrix and the at least one electrically conductive layer comprises electronically conductive polymer and a conductivity enhancing agent.

There is significant interest in low cost flexible electronic displays. Typically, such displays comprise a light modulating component embedded in a binder (most commonly polymer) matrix that is coated over a conductive plastic support. Broadly speaking, a light modulating component is a material that changes its optical properties such as its ability to reflect or transmit light in response to an electric field. The light modulating component may be a liquid crystalline material such as a nematic liquid crystal, a chiral nematic or cholesteric liquid crystal or a ferroelectric liquid crystal. The light modulating material may also be a water insoluble liquid containing particles that undergo electrophoresis or motion such as rotation or translation in response to an electric field. Displays comprising a liquid crystalline material in a polymer matrix are referred to as polymer dispersed liquid crystal (PDLC) displays.
There are two main methods for fabricating polymer dispersed liquid crystal devices: emulsion methods and phase separation methods. Emulsion methods have been described in U.S. Pat. Nos. 4,435,047 and 5,363,482. The liquid crystal is mixed with an aqueous solution containing polymer. The liquid crystal is insoluble in the continuous phase and an oil-in-water emulsion is formed when the composition is passed through a suitable shearing device, such as a homogenizer. The emulsion is coated on a conductive surface and the water allowed to evaporate. A second conductive surface may then be placed on top of the emulsion or imaging layer by lamination, vacuum deposition, or screen printing to form a device. While the emulsion methods are straightforward to implement, droplet size distributions tend to be broad resulting in a loss in performance. For cholesteric liquid crystal devices, also referred to herein as CLC devices, this typically means reduced contrast and brightness. Phase separation methods were introduced in an effort to overcome this difficulty.
Phase separation methods have been outlined in U.S. Pat. No. 4,688,900 and in Drzaic, P. S. in Liquid Crystal Dispersions, pgs. 30-51, published by World Scientific, Singapore (1995). The liquid crystal and polymer, or precursor to the polymer, are dissolved in a common organic solvent. The composition is then coated on a conductive surface and induced to phase separate by application of ultraviolet (UV) radiation or by the application of heat or by evaporation of the solvent, resulting in droplets of liquid crystal in a solid polymer matrix. A device may then be constructed utilizing this composition. Although phase separation methods produce dispersed droplets having more uniform size distributions, there are numerous problems with this approach. For example, the long term photostability of photopolymerized systems is a concern due to the presence of photoinitiators that produce reactive free radicals. Photoinitiators not consumed by the polymerization process can continue to produce free radicals that can degrade the polymer and liquid crystals over time. Furthermore, it is also known that ultraviolet radiation is harmful to liquid crystals. Specifically, exposure to ultraviolet radiation can lead to decomposition of the chiral dopant in a cholesteric liquid crystal mixture, resulting in a change in the reflected color. The use of organic solvents may also be objectionable in certain manufacturing environments.
U.S. Pat. Nos. 6,423,368 and 6,704,073 propose to overcome the problems associated with the prior art methods through the use of droplets of the liquid crystal material prepared using a limited coalescence process. In this process, the droplet-water interface is stabilized by particulate species, such as colloidal silica. Surface stabilization by particulate species such as colloidal silica is particularly preferred as it can give narrow size distribution and the size of the droplets can be controlled by the concentration of the particulate species employed. The materials prepared via this process are also referred to as Pickering Emulsions and are described more fully by Whitesides and Ross (J. Colloid Interface Sci. 169, 48 (1995)). The uniform droplets may be combined with a suitable binder and coated on a conductive surface to prepare a device. The process provides improvement in brightness and contrast over prior art processes. It also overcomes some of the problems associated with photoinitators and ultraviolet radiation. However, there is still much room for improvement, particularly in terms of the switching voltage or the voltage needed to change the orientation of the liquid crystal from one state to another. The latter has a significant effect on the overall cost of the display. A low switching voltage is extremely desirable for low cost displays.
The device described by U.S. Pat. Nos. 6,423,368 and 6,704,073 suffers from drawbacks because of the structure of the coated layer. Undesirably, there may be more than a monolayer of droplets between the two electrodes. Furthermore, the process of coating a heated emulsion of the liquid crystal in a gelatin binder onto a substrate with a conductive layer and subsequently lowering the temperature of the coating to change the state of the coated layer from a free flowing liquid to a gel state (referred to as a sol-gel transition) prior to drying the coating results in an extremely uneven distribution of droplets of liquid crystal. At the microscopic scale there are regions of the coating containing overlapping droplets and other regions with no droplets at all between the electrodes. The uneven distribution of droplets results in a decrease in contrast and an increase in switching voltage.
U.S. Pat. Nos. 6,271,898 and 5,835,174 also describe compositions suitable for flexible display applications that employ very uniform sized droplets of liquid crystal in a polymer binder. However, no attempt is made to control the thickness or the distribution of droplets in the coated layer resulting in less than optimum performance.
U.S. patent application Ser. No. 10/718,900 shows that the maximum contrast in a bistable chiral nematic liquid crystal display prepared by the limited coalescence method is obtained when the uniform liquid crystal domains or droplets are coated as substantially a monolayer on the conductive support. The bistable states in these chiral nematic liquid crystal displays are the planar reflecting state and the weakly scattering focal conic state. Back-scattering of light from the weakly scattering focal conic state increases drastically when there is more than a monolayer of droplets between the conductive surfaces. While the method provides displays with an improvement in brightness and contrast, it still falls short of optimum performance because the gelatin binder is made to undergo a sol-gel transition prior to drying of the coating resulting in an uneven structure.
Rudhardt et al. (Applied Physics Letters vol. 82, page 2610, 2003) describe a method of fabricating a light modulating device wherein a composition containing very uniform droplets of liquid crystal in an aqueous solution of polymer binder is spread on an indium tin oxide (ITO) coated glass surface and the water allowed to evaporate. The droplets of liquid crystal spontaneously self-assemble into a hexagonal close-packed (HCP) monolayer. A second indium tin oxide coated glass surface is placed over the coated layer of droplets as the top electrode to complete construction of the device. A uniform monolayer thickness is achieved for the coated layer and the close-packed distribution of droplets is also extremely well defined. Both features result in a low switching voltage. However, there are numerous problems with this approach. Firstly, the uniform droplets of liquid crystal are prepared by extrusion through a thin capillary into a flowing fluid. When a droplet at the tip of the capillary grows to reach critical size, viscous drag exceeds surface tension and breakoff occurs, producing highly monodisperse emulsions. Clearly, this method of creating one droplet at a time is not suitable for large scale manufacture. Secondly, the method by which the second (top) electrode is applied may be suitable for construction of small scale displays on rigid substrates such as glass but is not viable for large area low cost displays on flexible substrates. A single substrate approach wherein the second electrode is simply coated or screen printed is preferable to a two substrate approach wherein the second electrode is prepared separately and then contacted by lamination.
U.S. Pat. Publication Nos. 2003/0137717A1 and U.S. Pat. Publication Nos. 2004/0217929A 1 indicate that a close-packed monolayer of droplets of the light modulating component may be desirable for obtaining high brightness and contrast in a polymer dispersed electrophoretic display. However the method of making droplets described in these applications is a standard emulsification process that does not result in emulsions having a narrow size distribution that is desirable for obtaining close-packed monolayers by spontaneous self-assembly. The preferred method of preparing droplets in U.S. Pat. Publication Nos. 2003/0137717A1 and U.S. Pat. Publication Nos. 2004/0217929A1 also involves encapsulation resulting in droplets or capsules in the size range of 20 to 200 microns with wall thickness of 0.2 to 10 microns. The relatively large droplet size and wall thickness result in high switching voltages. The latter is particularly a problem for bistable cholesteric liquid crystal devices. Encapsulation is clearly not desirable but these applications do not teach how a second conducting layer is to be applied on top of the coated layer of droplets in the absence of encapsulation. In the absence of encapsulation, droplets of the light modulating component may directly come in contact with the organic solvent in the screen printed conducting ink leading to contamination or poisoning of the light modulating component. This is particularly a concern if the light modulating component is a liquid crystal material.
To overcome the difficulties of U.S. Pat. Publication Nos. 2003/0137717A1 and U.S. Pat. Publication Nos. 2004/0217929A1, U.S. Pat. Publication Nos. 2004/0226820A1 teaches that a close-packed monolayer of droplets may be obtained by using electro-deposition followed by washing after the droplets have been spread on a suitable surface using a coating knife or coating head such as a slot die coating head. However, the additional steps of electro-deposition and washing are cumbersome and not suitable for manufacturing on a large scale. Even with these additional steps, a close-packed monolayer of uniform thickness is not achieved. The root mean square (RMS) surface roughness is about 6 microns because of non-uniform droplets or capsules. This is a very high value of surface roughness that would result in irregular or incomplete curing if a ultraviolet curable screen-printed conducive ink is used as the second electrode. The irregular curing will result in increased switching voltages. Furthermore, a surface roughness of this magnitude will also result in significant non-uniformity of switching voltage across the area of the display since the switching voltage is directly related to the thickness of the coated layer.
U.S. patent application Ser. No. 11/017181 describes a novel method for polymer dispersed liquid crystal that overcomes the problems of the prior art. A uniform dispersion of liquid crystal droplets is prepared by the limited coalescence process. The droplets are mixed with a suitable binder and coated and dried on a flexible conductive support at a temperature above the sol-gel transition of the binder. The uniform droplets of liquid crystal spontaneously self-assemble to create a close-packed monolayer. The desired close-packed structure is then fixed or preserved by cross-linking the binder. Subsequently, a second aqueous layer containing gelatin is coated above the liquid crystal layer and allowed to dry at a temperature that is below the sol-gel transition of the binder. This second layer protects the liquid crystal material from the solvent in the conductive ink. A conductive ink is screen printed over this layer to complete construction of the device. The device may be manufactured using a low-cost process. Furthermore, it exhibits low switching voltage as well as good contrast and brightness. However, there is still room for improvement. In particular, it would be preferable to eliminate the need for cross-linking the binder after the liquid crystal layer has been applied in an effort to reduce process time. Furthermore, since switching voltage is directly proportional to thickness between the electrodes, elimination of the protective layer between the liquid crystal layer and the second electrode is also desirable.
U.S. Pat. No. 4,806,922 describes a method for polymer dispersed liquid crystals that uses polymer latex as the binder material in the layer containing the liquid crystal. But, once again, the method of making the droplets of liquid crystal is a standard emulsification process that does not result in emulsions having the narrow size distribution necessary for obtaining a close-packed monolayer by spontaneous self-assembly.
U.S. patent application Ser. No. 11/017181 also describes a method for polymer dispersed liquid crystals that uses polymer latex as binder material. In this case a limited coalescence process is used to prepare very uniform droplets of liquid crystal. However, in spite of this, the display exhibits high switching voltage that is undesirable.
In summary, the prior art describes a water soluble liquid crystal layer. The close-packed architecture of this layer is destroyed if an aqueous layer is coated above it in the absence of fixing or cross-linking. Also, solvent borne conductive layers cannot be directly coated on top of the liquid crystal layer as contact between liquid crystal and solvent may cause irreversible damage to the liquid crystal. A proposed solution to this problem lies in coating a protective barrier between the water soluble liquid crystal layer and the solvent-borne conductive layer. Unfortunately, this additional layer results in the need for increased voltage. Clearly, there is a need for a low-cost display based on water insoluble, hydrophobic binder material that exhibits low switching voltage as well as good contrast and brightness. There is also a need for a low-cost display having reduced thickness between the electrodes.

Display comprising liquid crystal droplets in a hydrophobic binder

Industrial Technology Research Institute


A clamp for gripping an edge of a plate that is mounted on the surface of a rotatable drum. The clamp includes a hinge, attached to the drum and including a pivot axis, and a gripper, formed to have a tip, operative to press the edge of the plate against the drum. The gripper is attached to the hinge so that the center of mass of the gripper is in a direction from the pivot axis that is generally opposite the direction of the tip from the pivot axis.

The present invention relates to clamps for attaching a plate to a rotatable drum and, more particularly, to clamps for attaching plates of various sizes to the drum of a so-called external-drum platesetter that can operate at very high rotation speeds.
Imagesetters, namely marking engines for plotting images on plates or sheets of film, of the so-called external-drum type, are known in the art, Typically, a sheet is attached to the outer surface of a rotating drum and held in contact with the surface by a vacuum system, which has orifices distributed over the surface. Often, such an imagesetter is required to handle sheets of various sizes. U.S. Pat. No. 5,383,001 to Bosy, addresses such a need, by providing a suitable design of the vacuum system.
External-drum platesetters are a particular category of external-drum imagesetters, wherin the image is plotted on a light-sensitive printing plate. Printing plates are generally made of metal and therefore they are stiffer than films and their mass per unit area is much higher. Thus, when a plate is attached to the drum, it requires a greater force to keep it in contact with the drum's surface at any given rotational speed, to counteract the centrifugal force, than is required by a film. Consequently, a vacuum system to hold plates on the rotating drum must be more efficient and more powerful than that used for holding films. However, even with a powerful vacuum system, there is a danger of failure, due to a bend or a bulge at the edge of the plate. Moreover, since in a vacuum system the forces holding the plate are exerted by atmospheric pressure, they have an upper limit. Above a certain rotational speed the centrifugal force per unit area exceeds atmospheric pressure and any plate attachment system solely based on vacuum would then totally fail. Such failures may cause the entire plate to fly off the drum by centrifugal action--which would be disastrous for the entire machine. Therefore platesetters require mechanical attachment means--either to assist the vacuum system and guard against drastic failure, or as the main holding means, possibly still aided by vacuum. One common and useful such means is clamps mounted on the drum and operative to hold down the edges of the plate.
Clamps and grippers for holding a plate onto a rotatable drum have been known in the art. For example, clamps (also called grippers) are generally used in offset printing presses to hold the printing plate onto a cylinder. During operation, centrifugal forces act to cause a pulling force on each edge of the plate, such that tends to pull the edge from the clamp. Therefore in printing presses, clamps are designed to exert enough gripping force to exceed that required for countering the centrifugally induced pulling force, at maximum expected rotational speed, by a safety margin. Such clamps are disadvantageously cumbersome for mounting on platesetters and, moreover, difficult to activate (i.e. to open for accommodating the plate), because they must include either a heavy bolting or leveraging mechanism or a very strong spring-loading mechanism. A clamp on a printing cylinder must also exert a positive stretching force on the plate, in order to assure contact between the plate and the cylinder over its entire surface.
U.S. Pat. No. 3,203,074 describes an improved clamp, in which the gripping and stretching forces increase by centrifugal action in proportion to the rotational speed. A clamp with such a centrifugal action (also termed dynamic clamp) may overcome the disadvantages discussed in the previous paragraph. U.S. Pat. No. 4,250,810 discloses a further improved clamp with centrifugal action whereby the gripping and stretching forces can be independently adjusted.
It is noted that in platesetters, there usually is also a vacuum system, which assures contact between the plate and the drum over its entire surface, and that therefore no stretching force, but only a gripping, force, is required at the edges of an attached plate. U.S. Pat. No. 5,335,046 discloses a clamp for the drum of a platesetter with a mechanism that centrifugally induces a gripping force. There is a row of such clamps for the leading edge and another one for the trailing edge. The mechanism includes a weight, connected to the clamp by a rod, located inside the drum near the opposite surface. The clamp is opened by means of a piston and cylinder assembly, activated by supplied pressurized air. The clamp mechanism of the '046 patent has two serious drawbacks: (1) It is relatively complicated, with a relatively large number of parts, and thus is expensive to manufacture. (2) It does not conveniently accommodate plates of various sizes. The '046 patent does disclose the possibility of providing a row of trailing edge clamps for each plate size; however, such an arrangement is even more expensive and, furthermore, does not accommodate small variations in plate size. The secondly listed drawback also applies to other types of clamps of prior art, such as those discussed hereabove.
There is thus a widely recognized need for, and it would be highly advantageous to have, a clamping system, for attaching a plate to a rotatable drum, that is dynamic, i.e. has a centrifugally induced gripping action, is adaptable to any plate size and easy to operate and is of simple design, having a small number of parts.

Dynamic clamps for external drum platesetter


An electrical circuit protection system provides circuit protection in an electrical power distribution system. The electrical circuit protection system according to one embodiment comprises: an automatic reset circuit breaker; a commutation module electrically connected to the automatic reset circuit breaker; and a controller that sets a state of the commutation module based on detected state of the automatic reset circuit breaker and externally input commands.

1. Field of the Invention
The present invention relates to electrical power distribution systems for vehicles, and more particularly to a circuit protection scheme for an electrical power distribution system using an electronically resetable circuit breaker arrangement.
2. Description of the Related Art
Vehicles, airborne, terrestrial or marine, that incorporate an electrical generating system to power their functions generally have a primary and a secondary electrical distribution system. The primary electrical distribution system usually handles the high wattage power produced by generator(s), and directs that power to a secondary electrical distribution system. The secondary electrical distribution system divides the incoming power among many small electrical circuits that feed individual systems and equipment on the vehicle. The secondary electrical power distribution among systems and equipment of the vehicle is typically achieved through a number of circuit breakers mounted collectively in circuit breaker panels that provide for downstream wire and circuit protection. The circuit breaker panels are within reach of the vehicle operator. Additionally, such secondary power distribution systems may also include remotely located switching devices such as relays or semiconductor devices, located in other panels or control units, and used to turn on and off loads in response to operator commands.
Traditional vehicle designs use circuit breaker panels that are physically located in the operator compartment of the vehicle. The circuit breakers are typically made of simple, low cost, highly reliable thermo-mechanically activated components that open automatically and autonomously when subjected to an overcurrent condition. Such circuit breakers are manually closed or reset, by tactile operator action. Although simple and effective, such circuit breakers add considerable weight and manufacturing cost due to their associated circuit breaker panel assembly weight. In addition, large and heavy wires and cables are needed to realize system connections between equipment bays, the operator compartment, and the location of circuit breakers and electrical loads.
Significant manufacturing cost reduction can be achieved if the secondary electrical distribution system, including the circuit breaker function, is located in close proximity to the systems and equipment of a vehicle. The cost reduction comes from decreased size of interconnecting wire gauges, smaller wire lengths, and lower installation design costs for fewer secondary power panels installed. In this case, however, the operator is remotely located from the circuit breakers during vehicle operation, and hence the operator cannot manually reset circuit breakers or deactivate circuits when needed.
However, the cost reduction mentioned above can still be achieved if the operator of the vehicle can control the circuit breaker panel function remotely. Solid-state circuits containing solid-state power controllers (SSPCs) have attempted to address this need. An SSPC is a semiconductor based switching device that typically relies upon a metal-oxide semiconductor field effect transistor (MOSFET) as the switching element. When incorporated into an Integrated Secondary Power System (ISPS), the SSPCs can provide a manner of remote switching and circuit protection through electronic communication.
SSPCs, however, have their own set of problems that tend to offset their advantages. More specifically, SSPCs are made of high cost semiconductor materials. The actual switching device in an SSPC (e.g. MOSFET) exhibits an increased "on state" resistance when compared to a circuit breaker. That increased resistance leads to increased voltage drop to downstream services and increased power dissipation, leading to increased weight and cost for additional thermal management systems. In addition, a short circuit failure mode occurs very often in SSPCs. Because the semiconductor devices used as SSPCs, such as MOSFETs, do not inherently emulate the basic function of circuit breakers, complex controllers and algorithms are needed to program the SSPCs so that their behavior mimics that of a circuit breaker. Reliability of SSPCs is lower due to the increased part count that comes with complex controllers. Reliability of SSPCs is also impacted by excessive heating and/or insufficient cooling conditions typical to vehicle environments. Therefore, while the SSPCs enable remote control, they do so at a significantly higher cost, reduced electrical performance, and low reliability.
A few publications have studied circuit protection schemes for electrical power distribution systems. One such technique is described in U.S. Pat. No. 5,440,441, entitled "Apparatus for Protecting, Monitoring, and Managing an AC/DC Electrical Line or a Telecommunication Line Using a Microprocessor." With the method described in this work, parameters of a switch are recorded by a control system, which then commands the switch to open when recorded parameters indicate an over-current condition. A controlled switch does not however emulate the basic function provided by circuit breakers. Controlled circuit breakers and switches are also used in U.S. Pat. No. 4,964,058, entitled "Power Management and Automation System."
Another technique is described in U.S. Pat. No. 6,577,963, entitled "Programmatic Resetting of Circuit Breakers." In this publication however, a priori information about components and their arrangement in the electrical power distribution system is needed to decide on a reset strategy.
Another technique is described in U.S. Pat. No. 4,853,820, entitled "Electronic Circuit Breaker Systems.". However, in the apparatus described in this work, an automatic reset circuit breaker is not used. Hence monitoring of residual currents passing through the electrical power distribution system is needed, in order to decide when it is safe to restore full electrical operating current to the electrical power distribution system.
A disclosed embodiment of the application addresses these issues by utilizing a hybrid electronically resetable circuit protection system that retains the basic function provided by circuit breakers, does not use solid state devices for circuit protection and switching functions, and can be remotely controlled.

Hybrid system for electronically resetable circuit protection


Steerable towcraft having a buoyant body upon which a person can ride, a towline attached to body and adapted for connection to the pulling vessel, a fin on the under side of the body for guiding the body through water, and a steering line connected to the towline at a point spaced from the body. By pulling on the steering line, a person riding on the body can change the angle of the fin relative to the towline, and thereby control the direction in which the towcraft is moving. Water is taken in from beneath the body and sprayed in the form of a roostertail into the air behind the craft as it travels through the water. In some embodiments, a whistle or other noisemaker is actuated by the water forming the roostertail.

1. Field of Invention
This invention pertains generally to water sports and, more particularly, to watercraft of the type towed behind a boat or other vessel.
2. Related Art
Children and others enjoy being towed behind boats on a variety of buoyant devices such as inner tubes and the like. Such devices are generally attached to the towing vessels by towlines, and there is no way to steer them. They simply go where the boat takes them, and that can become relatively unchallenging and/or uninteresting when the boat is going slowly and in a straight line.
At higher speeds, when the boat makes a turn, centrifugal force can cause the device to swing outside the wake of the boat and to travel substantially farther and faster than the boat itself is travelling. The rider has no control over where or how fast he is going, and in the event of debris or other obstacles in the water, about all the rider can do to protect himself is let go of the line or fall off the device. With a boat travelling at a speed of 25 mph, the tube can travel at speeds as high as 40 to 50 mph, or more, and jumping or falling into the water at those speeds is not something that most people would want to do.


If a flux contains an amount of thixotropic agent necessary for obtaining the effect of suppressing a heating sagging, the amount of flux residue increases, and, if applied for uses that do not involve washing, a large amount of flux residue derived from the thixotropic agent remains around the soldered portions, thereby affecting chemical and electrical reliability; and that washing performance is poor in uses involving washing of the flux residue. Accordingly, this soldering flux contains nanofibers of one or more kinds from among polysaccharides, modified polysaccharides, and incompletely modified polysaccharides being modified from polysaccharides into modified polysaccharides, by an amount of 50 wt ppm or more and 3000 wt ppm or less with respect to a total amount of flux.

In general, fluxes used for soldering have effects of chemically removing metal oxides present on solder and the metal surface of a joint target to be soldered and allowing the movement of metal elements at the boundary between the two. Therefore, by soldering using the flux, an intermetallic compound can be formed between the solder and the metal surface of the joint target, so that strong joint can be obtained.
In a soldering paste including such a soldering flux and metal powder, thixotropy is imparted to the soldering paste by a thixotropic agent contained in the flux. Moreover, sagging of the soldering paste at the time of melting by heating is suppressed.
As the thixotropic agent, an aliphatic amide such as hydroxystearic acid bisamide, a wax (aliphatic ester) such as caster wax, or a synthetic polymer compound such as polyethylene glycol or polyethylene oxide is used (see, for example, Patent Document 1).
Further, as the thixotropic agent, a semi-synthetic polymer compound such as methyl cellulose, ethyl cellulose or hydroxyethyl cellulose is used (for example, see Patent Document 2).


A tray-type component supply device includes an exchanging table configured to lift and lowered between an upper position and a lower position, a conveyance section configured to receive a tray from the exchanging table and convey the tray, and a control section configured to receive a detection signal from the detection sensor and cause the driving section to operate the exchanging table, the control section including an abnormality detecting section configured to detect an abnormal state in which a height position of the exchanging table becomes unidentified, a retraction operating section configured to cause the exchanging table to move to the retraction position at a low speed when the abnormal state is detected, and a calibration and restoration section configured to calibrate the height position of the exchanging table to restore a normal state.

A board work machine for producing a board on which multiple components are mounted includes a solder printing machine, a component mounter, a reflow machine, a board inspection machine, and the like. It is general practice to make up a board production line by providing these board work machines in a row. In them, the component mounter may include a tray-type component supply device using a tray on which components are arranged from time to time. In such a tray-type component supply device, generally, multiple trays are held, and when components are consumed, multiple components can be supplied by exchanging trays. Normally, one of a tray holding section, which is configured to hold multiple trays, and an exchanging table, which is configured to play a role of exchanging trays, performs the lifting and lowering operation, Patent Literature 1 discloses a technical example of a tray-type component supply device of this type.
An embodiment of Patent Literature 1 discloses an electronic component supply device including a lifting and lowering section for lifting and lowering multiple pallets each having a tray rested thereon while holding them and a feeder section for pulling out the pallets from the lifting and lowering section. Then, when power is supplied to the electronic component supply device, the lifting and lowering section and the feeder section perform their origin operations (encoder's origin confirming operations). As this occurs, a sensor is made to detect whether a pallet and the feeder section are in an interference position where the pallet and the feeder section may possibly come into interference with each other, and if any possibility of interference, the order in which the origin operations are performed is changed so as to avoid the possible interference.


A method for teaching golf. The method includes the use of a conventional golf club, a handle laser removably attached to a butt end of the golf club""s handle, a shaft laser removably attached to the golf club""s shaft, and a retractable target line having a tape marked with a centerline and at least one golf ball image. The handle laser is installed so as to shine a handle laser beam along the golf club""s shaft centerline extension in a direction opposite the golf club""s head. The shaft laser is installed so as to shine a shaft laser beam parallel to the golf club shaft such that the shaft laser beam passes immediately in front of the area of the head intended to strike a golf ball. The method includes the steps of addressing the golf ball image and swinging conventionally, ensuring that during appropriate arcs of the swing, either the handle laser beam or the shaft laser beam shine on the tape centerline, thus teaching the golf student to execute the entire swing within the perfect swing plane.

1. Field of the Invention
This invention relates to golf instruction, and in particular to an apparatus and method for teaching golf.
2. Background of the Invention
It is generally accepted that golf first emerged in Scotland around 1100 AD. It was based on a Roman game called paganica, which used a bent stick and a leather ball stuffed with feathers. Golf was banned in Scotland from 1457 until 1502 by King James II because its popularity threatened archery practice, which was necessary for national defense. In 1502 England and Scotland signed a treaty of perpetual peace, and the play of golf resumed.
Until 1848 golf was played with a feather-stuffed leather ball called xe2x80x9cthe featheryxe2x80x9d. In 1848 golfers started using a solid gutta-percha ball called xe2x80x9cthe guttyxe2x80x9d, and in 1899 an American inventor introduced the liquid-center golf ball.
The oldest golf club in continuous existence is the Ancient Golf Club of St. Andrews, located in Edinburgh, Scotland (established 1744). This club established many of the standards of the game, including fixing the length of the course at 18 holes. The Royal Montreal Golf Club was established in 1873, and ranks as the oldest North American golf club. In the United States, the St. Andrews Golf Club was established in Yonkers, N.Y. in 1888, and was the first United States golf club.
Today, more people play golf than any other outdoor sport. More than 16 million people play golf in the United States alone every year. The game has become popular in many places, including the United States, Canada, England, Western Europe, and Japan.
Conventional golf courses feature either nine or 18 holes. A round of golf consists of 18 holes played in a pre-determined sequence. During play, golfers attempt to keep the ball on the fairway, a stretch of mowed grass between the tee-off site and the putting green, which contains the hole into which the ball must be sunk. The edges of the fairways frequently have obstacles called bunkers. These bunkers may be a mound or a sand trap, or sometimes a body of water such as a stream, pond, lake, river or ocean.
About half the holes of an 18-hole course are medium holes, and measure from approximately 280-455 yards in length. The other holes are divided between short holes (less than 280 yards) and long holes (longer than 485 yards). Consequently, 18-hole golf courses occupy between 90 and 250 acres.
The large area of ground required for golf courses and the length of the individual holes necessitates a smooth, accurate swing on the part of the golfer. Ideally, the golf club should swing within a plane containing the golf ball to be hit, from initial address of the ball, through back-swing, through the forward part of the swing, and finally throughout the follow-through portion of the stroke. This plane is referred to as the xe2x80x9cperfect swing planexe2x80x9d, and it is important that the golfer keep the golf club within the perfect swing plane throughout the stroke as much as possible, in order to maximize the solidity and accuracy of the shot.
One problem associated with teaching golf students to swing within the perfect swing plane is the invisible nature of this plane. The student is told to keep his swing within a plane containing the ball, yet this plane is invisible and, for some students, difficult to visualize. In addition, due to the invisible nature of the plane, it is difficult for the student to tell if his swing is indeed within the perfect swing plane, and consequently it is hard to make appropriate swing corrections to advance in the learning process.
One solution to the problem of student visualization of the perfect swing plane is to attach lights to golf clubs or other swingable devices, and have the student watch the lights. A variety of light types have been proposed for this purpose, including incandescent, stroboscopic, and laser.
Existing Designs
A number of patents have been granted which teach a light mounted on the butt end of a golf club or other swingable device. U.S. Pat. Nos. 4,693,479, 4,913,441, 5,544,888 and 5,655,973 were granted to McGwire, Freer, Pellegrini and McPherson, Jr. respectively for butt-mounted lights. While these designs permitted the student to visually observe the swing plane while the butt end of the club or other swingable device was pointing down towards the ground, these devices made no provision for tracing the swing plane during that part of the swing that the head end of the golf club or other swingable device was pointing toward the ground (as during the forward portion of the swing). In addition, none of these inventions provided a clearly defined target line against which to compare the butt-mounted light tracing.
A second school of thought relating to club-mounted lights taught lights either mounted in the head end of a golf club, or lights mounted on the shaft pointing downwards, toward the golf club head. U.S. Pat. Nos. 4,971,328, 5,000,456, 5,161,802, 5,467,991 and 5,472,204 were granted Hemberg, Rabold, Daechsel, White IV et al., and English et al. for such designs. While these designs permitted the student to visually observe the swing plane while the head end of the club or other swingable device was pointing down towards the ground, these devices made no provision for tracing the swing plane during that part of the swing that the butt end of the golf club or other swingable device was pointing toward the ground (as during the backswing and follow-through portions of the swing). In addition, none of these inventions provided a clearly defined target line against which to compare the light tracing.
Still another approach involved mounting lights to the top of a golf club head, so the golf student could more easily observe the trajectory of the golf club head during a swing, especially under dim lighting conditions. U.S. Pat. Nos. 5,288,080 and 5,470,072 were granted Tice and Cunningham respectively for such devices. These designs did little more than highlight the golf club head to facilitate its visibility. In addition, they did not indicate the swing plane of the entire golf club, but rather the swing arc of the head only, thus providing potentially misleading information to the golfer.
Cunningham ""072 additionally taught a back-lit silicone pad against which to compare the golf club head trajectory in close vicinity to a ball target. This pad suffered from a number of disadvantages. The pad was of only short length, and thus rendered it""s use effective during only a short arc of the swing. In addition, the pad was cumbersome to transport, and complex, being electrically back-lit.
McCardle was granted U.S. Pat. No. 5,269,528 for a cylinder which incorporated a light at each end. While this device allowed the cylinder light tracings to be observed from two ends of the cylinder, no provision was taught to allow the lights to be mounted to a conventional golf club. Thus, a swing practiced with the ""528 cylinder taught the student how to swing the ""528 cylinder, not how to swing a conventional golf club. In addition, no clearly defined target line against which to compare the light tracings was disclosed.
Accordingly, it is an object of the present invention to provide an apparatus and method for teaching golf which teaches a golf student to swing within the perfect swing plane. Design features allowing this object to be accomplished include a handle laser, a shaft laser, and a retractable target line having an optically reflective tape with centerline and golf ball image. Advantages associated with the accomplishment of this object include increased solidity and accuracy of golf shots.
It is another object of the present invention to provide an apparatus and method for teaching golf which can be used in conjunction with existing golf clubs, without the need to modify the existing golf club in any way. Design features allowing this object to be accomplished include a handle laser clamp having a handle laser clamp aperture sized to grip a conventional golf club handle, and a shaft laser clamp having a first handle laser clamp aperture sized to grip a conventional golf club shaft. Benefits associated with the accomplishment of this object include increased flexibility in swinging golf clubs, and improved learning and transferability of learning results, because the actual club used to teach will be later used during play. In addition, no modifications need be made to existing golf equipment, such as drilling holes, etc., thus maintaining the integrity and balance of the golf clubs used.
It is still another object of this invention to provide an apparatus and method for teaching golf which is quick and simple to install and uninstall. Design features enabling the accomplishment of this object include a handle laser clamp having a handle laser clamp aperture sized to grip a conventional golf club handle, a shaft laser clamp having a first handle laser clamp aperture sized to grip a conventional golf club shaft and a retractable target line with lock. Advantages associated with the realization of this object include ease of use and convenience in storage and transportation.
It is yet another object of this invention to provide an apparatus and method for teaching golf which is inexpensive and readily available. Design features allowing this object to be achieved include the use of components made of off-the-shelf and readily available materials. Benefits associated with reaching this objective include reduced cost, and hence increased availability.


A bipolar transistor comprising a collector region of a first conduction type, and a subcollector region of the first conduction type at a first side of the collector region. The transistor further includes a base region of the second conduction type provided at a second side of the collector region, and an emitter region of the first conduction type which is provided above the base region on the side remote from the collection region. A carbon-doped semiconductor region is provided on the first side alongside the collector region. The bipolar transistor is characterized in that the carbon-doped semiconductor region has a carbon concentration of 1019-1021 cm−3 and the base region has a smaller cross section than the collector region and the collector region has, in the overlap region with the base region, a region having an increased doping compared with the remaining region. The carbon-doped semiconductor region prevents an outdiffusion from the zone of the collector region into the remaining region of the collector region.

Although applicable in principle to any desired bipolar transistors the present invention and the problem area on which it is based are explained with regard to DPSA transistors.
US 2002/0096742 discloses the introduction of a carbon-doped subcollector layer for reducing mechanical stresses and dislocations.
JP 2000-2162168 A discloses the introduction of a carbon-doped intermediate layer between collector and subcollector for the gettering of hydrogen that is implanted for the insulation of transistors.
DPSA (double polysilicon self-aligned) transistors are known e.g. from T. F. Meister et al., IEDM Technical Digest 1995, p. 739-741.
Their name stems from the fact that they use as p+-type base terminal and as n+-type emitter contact two p+-type polysilicon and n+-type polysilicon layers, respectively, which are deposited especially therefore. In this case, in the emitter window, the n+-type polysilicon emitter layer is insulated from the p+-type polysilicon layer of the base terminal in a self-aligned manner by means of a spacer. The DPSA transistor may contain both an implanted Si base and an epitaxially deposited SiGe base. The collector is usually connected via a buried layer that is buried in the substrate (also referred to as subcollector). On account of their lateral and vertical scalability and the low parasitic capacitance and resistance components the DPSA transistor structure is best suited to very high speed applications.
In order to make bipolar transistors suitable for ever higher frequencies, parasitic capacitances and resistances have to be reduced and charge carrier transit times have to be reduced. In the case of vertically constructed bipolar transistors, short transit times are achieved by means of very thin layers of emitter, base and collector.
A minimum diffusion of the dopants is crucial, because the layer thickness of the boron-doped base in the case of the npn transistor can only be chosen to be small enough that an outdiffusion of the boron into adjacent layers still does not entail any disadvantages. This is a central problem in the case of the npn bipolar transistor, because boron, besides the normal diffusion, additionally exhibits an accelerated diffusion induced by interstitial atoms.
Similar problems occur in the case of a phosphorus-doped collector, because phosphorus also has an accelerated diffusion through interstitial atoms which has the consequence that a doping profile present in the collector may be altered in an unintentional manner.
It is known that interstitial atoms arise e.g. as a result of oxidation and implantation. In particular, however, the deactivation of arsenic in highly doped layers (concentration of typically 1020 cm−3), such as e.g. in a buried subcollector layer in the bipolar transistor, also represents a source of interstitial atoms. In this respect, see P. M. Rouseau et al., Appl. Phys. Lett. 65 (5), 1995, "Electrical deactivation of arsenic as a source of point defects". Since interstitial atoms are highly mobile in silicon, even more remote sources can induce an accelerated boron or phosphorus diffusion and thus make it impossible to miniaturize the transistor geometry further. Moreover, it is thus not practical to reduce the sheet resistance of the buried subcollector layer by means of a higher arsenic doping owing to the increase in disturbing interstitial atoms.
Reducing the concentration of the interstitial atoms is of crucial importance therefore for the further improvement of the high-frequency properties of bipolar transistors.
In principle, the concentration of the interstitial atoms can be reduced in two ways. Firstly, interstitial atoms can be prevented from arising through corresponding process control, and, secondly, interstitial atoms that have arisen can be annihilated again.
Interstitial atoms that have arisen are annihilated for example by using carbon-doped silicon layers which serve as a sink for interstitial atoms. This principle is successfully applied for example in the SiGe:C heterojunction bipolar transistor, as described e.g. in A. Gruhle et al., Appl. Phys. Lett. 75(5), 1999, "The reduction of base dopant outdiffusion in SiGe heterojunction bipolar transistors by carbon doping".
Carbon doping of this type may usually be employed in this case in the base and/or in the emitter and/or in the collector as described in WO 98/26457 and US-2002/0,121,676 A1.
What is disadvantageous about the known procedure is that protection against accelerated diffusion is not completely possible, and, although it is possible to increase the effectiveness by means of higher carbon concentrations, this entails a degradation of the transistor characteristic curves and reduced charge carrier mobilities.
In particular, it is not possible to prevent interstitial atoms from arising from a buried subcollector region highly doped with arsenic because many indispensable process steps take place in the corresponding temperature range of between 500° C. and 900° C.
The only solution that has remained hitherto, therefore, has been merely to reduce the arsenic concentration in the buried subcollector region, which entails a disadvantage in that the sheet resistance of the subcollector region is increased and, accordingly, the high-frequency suitability of the transistor is impaired.

Bipolar transistor comprising carbon-doped semiconductor


A one piece maternity support for the relief of discomfort associated with the progressive changes in the human body associated with a normal pregnancy. The support has a body encircling upper band for the support of the lower uterine segment and a lower belt having a pair of tensionable arms that connect to the upper band to support the lumbar region and offer counter rotational force for the anteriorly tilted pelvis. The position of the lower arms is optimized to apply a constant pressure to the muscles above the hip joint providing relief from so-called hip pain associated with many pregnancies.

The present invention relates generally to devices providing abdominal support and lower back support for the relief of discomfort associated with normal pregnancy.
It is well known that the body changes associated with pregnancy give rise to conditions that can cause a woman significant discomfort or pain ranging from mild to severe. Among the body changes are:
Normal weight gain and the added weight of the developing fetus shift the iliac crest of the pelvis forward in what is called anterior pelvic tilt which in turn causes the lumbar region of the spine to assume an exaggerated s-curve. Attempts to correct ones posture lead to even more curvature and increased stress placed on the lumbar region especially from L3-L5. A sense of increased pressure in the abdominal region and lower back pain are common complaints. In addition to the aforementioned changes, the pelvic ligaments relax due to the production of relaxin which causes the cartilage of joints to become increasingly malleable which allows the bones to shift and displace causing pain. While often referred to generically as "hip pain", it encompasses a variety of conditions such as pelvic arthropathy.
Devices in the past that meant to address the related problems of lumbar support and abdominal support have fallen into several basic categories:
multi-piece units with wide abdominal bands and ribbed lumbar support, units integrated with and into an undergarment, those releasably detachable from an undergarment and single piece units worn over an undergarment or next to the skin.
User preference plays a significant role in the selection of a supportive device, each type having its relative advantages and limitations such as better lumbar or abdominal support respectively.
Previous devices that are one piece and worn over an undergarment or next to the skin appear to be the most closely related to the present invention. One of the significant limitations of the such devices is the absence of a means to relieve so-called hip pain and it is this limitation among others that the present invention addresses while improving the support means for the lower uterine segment and the lumbar region of the spine.

Lower uterine segment maternity support belt


A highly durable and compact chain disconnecting and connecting tool that may be used for a chain at a sprocket part for winding the chain and that can receive an operational load at two places is provided. A first block has an engaged pressure actuating member coupling member. A second block is coupled with the first block turnably by the coupling member and has a cutout on one side and a through hole on another side of the block. The tool is attached to the chain from an opening while positioned engagement with an edge projection of a tap bolt that is screwed with the first block and with the cutout or the through hole.

1. Field of the Invention
The present invention relates to a chain disconnecting and connecting tool for use for chains such as a roller chain for disconnecting the chain by pulling (removing) a pin out of the chain and connecting the chain by caulking (deforming) an end of a pin of a joint link (chain linking member) and more specifically to a chain disconnecting and connecting tool suitably applied to a motorcycle driving roller chain.
2. Related Art
Heretofore, the present applicants have proposed a chain disconnecting and connecting tool as disclosed in Japanese Patent No. 3431361 for example. This tool has first and second bodies whose right and left sides are opened in a direction of a longitudinal direction of a chain, that engage from each other in a vertical direction of the chain and that are coupled so as to be unable to relatively move in a direction of nipping the chain. The first body is provided with a pressure actuating member for pressing a pin or a plate of the chain and the second body is provided with a through hole through which the pin of the chain may penetrate and a slider having a pin abutting portion to which an end of the pin may abut.
The pin may be pulled out the chain and the chain may be disconnected by mounting the pin to be pulled out to the pressure actuating member and pressing the pressure actuating member toward the chain by means of screw engagement while adjusting the slider with the through hole. In contrast, the chain may be connected by caulking (deforming) an end of a pin of the chain by mounting the pin to be caulked (deformed) to the pressure actuating member and pressing the pressure actuating member toward the chain while adjusting the slider with the pin abutting portion.
Because the chain disconnecting and connecting tool described above has a center impeller structure with the first and second bodies, i.e., separate members, engaged in the vertical direction of the chain, the tool can fully sustain an operational load such as caulking (deformation) and may be downsized and lightened so as to be conveniently portable. Still more, the tool can nip a chain by separating the first and second bodies while attaching the chain to a motorcycle, so that workability could be improved.
However, because the chain disconnecting and connecting tool described above has had the center impeller structure in an operational state in which the first body is engaged with the second body, the operation is obliged to be carried out in a free span of the chain wound around between a driving sprocket wheel and a driven sprocket wheel. Therefore, there have been cases when the place to which the chain disconnecting and connecting tool is attached is limited, the operation becomes cumbersome or it becomes difficult to use the tool, depending on a shape of a swing arm of the motorcycle.
It is noted that although there also exists a chain disconnecting and connecting tool having a cantilever structure with a body block in a shape of C, this tool has had problems that in terms of durability, the body block is readily deformable due to the cantilever structure and that the tool would be large and heavy and be inconvenient to carry when a robust and highly rigid body block is used.
Accordingly, the present invention seeks to provide a chain disconnecting and connecting tool that solves the abovementioned problems by constructing the tool so that it may be used at a winding part of a sprocket of a chain and so as to receive an operational load at two places.


A method includes measuring a surface non-uniformity of a wafer. A current state of an etch processing tool is determined. The surface non-uniformity of the wafer is compared with the current state of the processing tool. An operating parameter of the processing tool is adjusted based on the comparison of the surface non-uniformity of the wafer with the current state of the processing tool. A system includes a processing tool, a plurality of measuring devices, and a process controller. The processing tool is adapted for etch processing of a wafer. The plurality of measuring devices measure a surface non-uniformity of the wafer and determine a current state of the processing tool. The process controller compares the surface non-uniformity of the wafer with the current state of the processing tool and adjusts an operating parameter of the processing tool based on the comparison.

1. Field of the Invention
This invention relates generally to semiconductor processing, and more particularly, to a method for feed-forward control of an etch processing tool.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today""s manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of steps that must be accurately executed to produce useful semiconductor devices. To maintain proper manufacturing control, a number of inputs are generally used to fine-tune the steps.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final testing of the completed device, are significantly different from one another and specialized to the point that the processes may be readily performed in different manufacturing locations that contain different control schemes.
Among the factors that affect semiconductor device manufacturing are wafer-to-wafer variations, start-up effects of manufacturing machine tools, and memory effects of manufacturing chambers. One of the process steps adversely affected by such factors is etch processing of semiconductor wafers.
Those skilled in the art will appreciate that etch processing may be used in conjunction with other semiconductor processing techniques, such as photolithography, deposition, and the like, to produce various circuit geometries on a surface of a wafer. Generally, etch processing comprises exposing at least a portion of the wafer to an etchant material. For example, features may be defined on a surface of the wafer through the use of a selectively patterned protective coating, such as photoresist, and by performing one or more etching processes. The protective coating is patterned to expose portions of the surface of the wafer to the etchant material. The exposed portions are removed during the etching process to produce the desired circuit geometries on the surface of the wafer.
Referring to FIG. 1, a cross-sectional view of a wafer 10 shown. In this illustrative embodiment, the wafer 10 comprised of a substrate 12, a stop layer 14, and an etch layer 16. Those skilled in the art will appreciate that, as a result of any number of processing variables, the etch layer 16 of the wafer 10 may become non-uniform, (e.g., its thickness may vary across the layer, its surface may be uneven or wavy, etc.) Although any number of surface topographies may manifest in the wafer 10 during processing, the wafer 10 generally exhibits center-to-edge non-uniformity after a chemical mechanical polishing operation is performed on the surface 17 of the etch layer 16. For example, as shown in FIG. 1, the thickness of the etch layer 16 may gradually increase from the center to the outer edge of the wafer 10, which is typically referred to as center-thin non-uniformity. Because of the center-thin non-uniformity of the etch layer 16, during an etching process, the portion of the etch layer 16 located at the center of the wafer 10 may be removed sooner than the portion of the etch layer 16 located at the outer edge of the wafer 10.
In FIG. 2, a trench 18 may be formed by selectively exposing the wafer 10 to a timed etching process. Those skilled in the art will appreciate that the duration of the etching process may vary depending upon, among other things, the thickness of the etch layer 16. Generally, the duration of the etching process is an engineering design decision based on approximations that may not adequately account for the non-uniformity of the etch layer 16 and other processing variables, such as wafer coverage of the etch layer 16, the non-uniformity of the etching process, and the like. In this embodiment, because of the center-thin non-uniformity of the etch layer 16, a portion of the stop layer 14 may be removed during the etching process. The degree to which the etching process is continued after the etch layer 16 is completely removed is called overetch. The amount of overetch is illustrated by the distance xe2x80x9cx.xe2x80x9d
Referring to FIG. 3, another cross-sectional view of a wafer 20 is shown. The wafer 20 may be comprised of a substrate 12, a stop layer 14, and an etch layer 16. Again, although a variety of surface topographies may manifest in the wafer 20 during manufacturing, the wafer generally exhibits center-to-edge non-uniformity. In this illustrative embodiment, the thickness of the etch layer 16 may gradually decrease from the center to the outer edge of the wafer 20, which is typically referred to as center-thick non-uniformity. Because of the center-thick non-uniformity of the etch layer 16, during an etching process, the portion of the etch layer 16 located at the edge of the wafer 20 may be removed sooner than the portion of the etch layer 16 located at the center of the wafer 20.
In FIG. 4, a trench 18 may be formed by selectively exposing the wafer 20 to a timed etching process. Again, the duration of the etching process may be an engineering design decision based on approximations. In this embodiment, because of the center-thick non-uniformity of the etch layer 16, a portion of the etch layer 16 may not be removed from the trench 18. The degree to which the etch layer 16 is not completely removed is called incomplete etch. The amount of incomplete etch is illustrated by the distance xe2x80x9cy.xe2x80x9d
Unfortunately, because of the possible non-uniformity and other processing variables, determining duration times for various etching processes is extremely difficult. For example, the duration of the etching process must adequately account for the non-uniformity of the wafer and other processing variables. One such processing variable includes etch rate non-uniformity of an etch processing tool. For example, during an etching process, the etch rate across the surface of a wafer may be non-uniform. In one embodiment, because of the surface non-uniformity of a wafer (e.g., center-thin, center-thick, etc.), the non-uniformity of the etching process may result in extreme overetch or incomplete etch of the wafer. For example, if the surface topography of a wafer is center-thin and the etch rate is center-fast, the center of the wafer may be severely overetched.
In one embodiment, with center-thin surface non-uniformity of a wafer, a degree of overetch at the center of the wafer may be required to ensure that the outer edge of the wafer is sufficiently etched. Alternatively, with center-thick surface non-uniformity of a wafer, a degree of overetch at the outer edge of the wafer may be required to ensure the center of the wafer is sufficiently etched.
Generally, when processing a wafer it is desirable to minimize overetch and incomplete etch. For example, it may be undesirable to overetch unnecessarily because the underlying layer is typically thinned during overetch, which may result in a decreased production yield. In addition, incomplete etch of wafers may also result in a decreased production yield.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
In one aspect of the present invention, a method is provided. The method includes measuring a surface non-uniformity of a wafer. A current state of an etch processing tool is determined. The surface non-uniformity of the wafer is compared with the current state of the processing tool. An operating parameter of the processing tool is adjusted based on the comparison of the surface non-uniformity of the wafer with the current state of the processing tool.
In another aspect of the present invention, a system is provided. The system includes a processing tool, a plurality of measuring devices, and a process controller. The processing tool is adapted for etch processing of a wafer. The plurality of measuring devices measure a surface non-uniformity of the wafer and determine a current state of the processing tool. The process controller compares the surface non-uniformity of the wafer with the current state of the processing tool and adjusts an operating parameter of the processing tool based on the comparison.

Feed-forward control of an etch processing tool


A hydraulic control valve to control a double-acting working cylinder having a piston with a piston rod on one side, at least four external connections, and a device to feed the fluid forced from the small stroke space of the working cylinder into the large stroke space while the piston rod is moving out, and further for independent switching of the working cylinder from the work stroke to slow movement with a subsequent holding state to release pressure from the small stroke space, and wherein a connection of the small stroke space to the tank can be switched on. The control valve has five control edges, with two separate line paths formed to feed the fluid forced out of the small stroke space back with a back-feed control edge and a pressure-release control edge is formed to release pressure from the small stroke space to the tank.

The invention concerns a hydraulic control valve to control a piston with a piston rod on one side with a double-acting working cylinder, whereby the control valve constructed in the piston-moving structure has at least four external connections with ring channels form in the valve housing, namely a pump connection (P), a connection (A 1) for a feed line to and from the large stroke space of the working cylinder, a connection (B) for a feed line to the small stroke space of the working cylinder, and a tank connection (T1) connected to the tank and whereby the control piston of the piston collar of the control valve has control edges arranged on It. through which the connections (P, A1, B, T1) can be connected to one another in both positions of the control piston in such a way that during the work stroke of the working cylinder, a back feed of the fluid forced out of the small stroke space into the large stroke space of the working cylinder takes place as the piston rod is moved out and a connection of the small stroke space to the tank can be switched on for stroke-independent switching of the working cylinder from the work stroke when moving slowly, with a subsequent standing state to release the pressure of the small stroke space of the working cylinder
A control valve with the above-mentioned characteristics is described in DE 10 2008059 436 83. The construction of the control valve should make possible a movement of the piston of the working cylinder with a differential effect, that is, a fast piston movement is envisioned, in which a back feed of the fluid forced out of the small stroke space of the working cylinder during the work stroke of the differential cylinder is envisioned, i.e. ,when the piston rod is moved out, so that the pump must deliver only the same supply quantity both during the work stroke of the working cylinder and during its back stroke with each insertion of the piston rod. To implement his back feed, a fifth internal ring channel is formed in the valve housing of the known control valve, which channel is connected through internal bridges formed in the valve housing to the ring space belonging to connection A. In the working position of the control piston during a back stroke, connection 8, which is connected to the small stroke space of the working cylinder, is connected to the ring channel belonging to connection A through the fifth ring channel and the internal bridges connected to it, so that the fluid forced out of the small stroke space is led to connection A and from there to the large stroke space of the working cylinder.
In addition, in the control valve known from DE 10 2008 059 436 B3, a control function is already achieved that, at least at the end of the working stroke, with the piston rod pulled almost completely out, the full force made available by the pump is no longer used to move the piston, but is used as a holding force. For this, in the control valve known from DE 10 2008 059 436 B3, it is envisioned that the housing-internal bridges leading away from the fifth internal ring channel to the ring spaces belonging to both connection A and to the tank connection are closed, whereby in a connection hole designed for this between the housing-internal bridges and the ring space belonging to connection A, a valve-internal check valve with a pass-through device directed to connection A and in the section of the housing-internal bridges leading to the ring space belonging to the tank connection in the connection hole going upstream from the housing-internal bridges, an externally controllable lock valve to open and close the connection from the internal ring channel to the tank connection T are arranged. If a switch is now made from the rapid piston movement with back feed to the full holding force, then by switching the valve-internal lock valve from its lock position to its open position, the connection between connection B and connection T is opened. With this, the additional back feed of fluid forced out of the small stroke space of the working cylinder is interrupted and the small stroke space is released directly to the tank, so that the pressure acting on the large surfaces of the piston of the working cylinder in the large stroke space is not longer counteracted by pressure in the small stroke space of the working cylinder, and accordingly the holding force against the state while the piston rod is moving out is in any case doubled by the symmetric design of the working cylinder.
In a control valve of this kind, the problem results that during the work stroke of the working cylinder, the fluid forced out of its small stroke space during the entire work stroke is directed over the same control edges of the control piston from B to A 1 or T1. While during the rapid piston movement of the control piston a correspondingly larger volume stream is forced out of the small stroke space and through connection B and the associated control edges from B to A1 into the large stroke space, this volume stream during the holding place or during the transition to it is clearly lower, so that for this work phase of the working cylinder, the control edges from B to A 1 are designed too large The invention is therefore based on the task of providing a control valve designed for different phases during the work stroke, namely during rapid forward movement of the piston and during the subsequent holding phase, according to the generic characteristics, so that the hydraulic tension of the working cylinder is adapted through the control to the volume stream flowing at each time.
The solution of this task, including advantageous embodiments and further developments of the invention can be seen from the content of the patent claims attached to this description.
The invention envisions, in its basic thought, that on a control valve with at least three piston collars with five control edges formed on it, two separate line paths for the fluid forced out of the small stroke space during the work stroke of the piston are established, of which the first, a line path formed as a back feed for the supply and discharge line connected to the small stroke space through a recess acting as a back-feed edge connected to the large stroke space of the working cylinder and the second, a line path formed to connect the small stroke space to the tank, a line path formed to connect the small stroke space to the tank, leads through a pressure-release control edge formed on an assigned piston collar of the control valve, whereby the recess in the assigned control piston is for the fluid stream forced out of the small stroke space of the working cylinder during slow movement and is designed to be smaller than the other recesses of the piston collar formed for the other control edges.
An advantage of the present invention is that the work phase of holding the piston with full holding force now is arranged with a smaller control edge corresponding to a lower volume stream on the piston collar, through which an exact hydraulic tension for the working cylinder is ensured during all work phases. Switching with the lock valve that is still required is all simpler to achieve than the use of the path valve envisioned in the state of the art.

Hydraulic control valve for a one-sided operating differential cylinder having five control edges


A round baler having a bale forming chamber including one or more transversely mounted rolls and at least one elongated belt having opposing ends spliced together to form a continuous band. The splice includes a first and a second series of similar side-by-side loops connected to and extending from the respective opposing ends of the belt, and an attaching element extending through the first and second series of loops to maintain the opposing ends of the belt in alignment and close proximity to each other. Retention components affixed to the attaching element retain it in operative relationship to the first and second series of loops and are disposed outwardly of the outer loops.

Round balers generally have a bale forming chamber defined by an apron comprising an array of side-by-side belts, transverse slats trained on chains, a plurality of rolls or a combination of these various elements, e.g., rolls and belts. During field operation, crop material such as hay is picked up from the ground as the baler traverses the field and is fed into a fixed or adjustable diameter chamber where it is rolled up to form a compact cylindrical bale. The formed bale is wrapped in its compacted form while still inside the bale forming chamber by net, twine or the like, prior to ejecting the bale from the chamber onto the ground for subsequent handling.
Round balers of the general type mentioned above comprising a chamber defined (at least partly) by a plurality of side-by-side longitudinally extending belts supported on a plurality of transverse rollers, frequently utilize belts of a predetermined length with the opposing ends secured together to form a continuous band. The ends are spliced together by using known techniques, one of the most common of which is disclosed in U.S. Pat. No. 4,371,580, issued on Feb. 1, 1983. This technique, designated as "Prior Art" and shown in FIG. 2 of the drawings, includes the use of a rod 2 threaded through first and second series of loops extending from the opposing ends of the belt 3. The ends of rod 2 are bent to hold it in place and thereby permit the splice to retain belt 3 in its continuous band configuration.
Another known technique is disclosed in Publication No. LIT 1217 issued by the Clipper Belt Company of Grand Rapids Mich., wherein a similar arrangement is contemplated. This technique, illustrated in FIGS. 3-5, employs a clip fastener 4 (FIG. 3) positioned as shown in FIG. 4 and crimped to the rod in a conventional manner as shown in FIG. 5.
Although prior art round baler belt splice arrangements have met with varying degrees of success, no solution exists that goes to the root of the problem, i.e., the need to provide a simple and inexpensive splice that enhances the life of the continuous round baler belt and thereby reduce down time which in turn results in an improvement in overall reliability of the machine.


A small broadband cross-connect system (10) includes a two-stage matrix (12) for processing and cross-connecting optical and electrical telecommunication network signals. An administration subsystem (14) provides centralized control and synchronization to the two-stage matrix (12). The two-stage matrix (12) may be expanded from 96 ports to 192 ports in a cost and space effective manner.

Digital cross-connect systems are an integral part of today's modern telecommunications transport network. They are increasingly used by all service providers including exchange carriers, long distance carriers, and competitive by-pass carriers. Significant technology advancements have allowed digital cross-connect systems to evolve from narrowband grooming and test applications to cross-connection of larger network signals in wideband and broadband frequency domains.
A broadband system is typically used to terminate high speed SONET optical and electrical signals in order to path terminate and groom lower speed broadband signals. The broadband system also supports performance monitoring and test access functions. Typical broadband cross-connect systems use either single stage or three stage Clos matrix architecture. In the three stage matrix architecture, the cross-connect includes switches grouped into an originating stage, a center stage, and a terminating stage. The three stage matrix architecture is best suited for maximum capacity applications for cross-connecting a large volume of signals. The single stage matrix architecture organizes the single stage matrices in rows and columns, which results in a higher number of switches than the three stage architecture.
For an application that requires a small capacity cross-connection (48 to 192 ports), the three stage and single stage architecture have proven to be costly and cumbersome. Accordingly, there is a need for a digital cross-connect system that is fully non-blocking, reliable, cost effective, and space efficient.

Broadband digital cross-connect system architecture


Embodiments of the present invention relate to the use of placental alkaline phosphatase, and other members of the alkaline phosphatase family, to enhance protein synthesis in the muscle as well as the survival of non-cancerous differentiated cells in the muscle, adipose and other tissues. The ability of alkaline phosphatase to selectively enhance the survival of healthy cells and increase protein synthesis has many therapeutic applications. The use of alkaline phosphatase may prevent the loss of body weight and muscle mass typically experienced by diseased (such as cancer) or aging patients, or developing fetuses subjected to harmful conditions, or by patients who are treated with a toxic therapy including chemotherapy.

One cause of disability, particularly in elderly people, is muscular atrophy or the loss of muscle mass, also known as sarcopenia. Aging-related muscular atrophy partly reflects impaired protein synthesis and activation of catabolism [Morley, J. E., Baumgartner, R. N., Roubenoff, R., Mayer, J. and Nair, K. S. (2001), "Sarcopenia," J. Lab. Clin. Med. 137, 231-243]. Critical illness, including advanced cancer, poorly controlled type 1 diabetes, trauma, sepsis, extensive burn injury, major surgery, and muscular dystrophy are also associated with muscular atrophy.
Cancer patients often experience cachexia characterized by a progressive decrease in both adipose tissue and skeletal muscle mass [van Leeuwen, I. M. M., Zonnefeld, C. and Kooijman, S. (2003), "The embedded tumour: host physiology is important for the evaluation of tumour growth," Br. J. Cancer 89, 2254-2263]. Natural toxins, such as streptozotocin (STZ), radiotherapy, and various chemotherapies, such as cisplatin (CisPt), doxorubicin, mytomycin C and etoposide, also seem to induce reduction in the muscle and adipose tissue mass [Li, L., Seno, M., Yamada, H. and Kojima, I. (2003), "Betacellulin improves glucose metabolism by promoting conversion of intraislet precursor cells to β-cells in streptozotocin-treated mice," Am. J. Physiol. Endocrinol. Metab. 285, E577-E583; Baracos, V. R. (2001), "Management of muscle wasting in cancer-associated cachexia," Cancer 92, 1669-1677; Chen, H., Carlson, E. C., Pellet, L., Moritz, J. T. and Epstein, P. N. (2001), "Overexpression of metallothionein in pancreatic β-cells reduces streptozotocin-induced DNA damage and diabetes," Diabetes 50, 2040-2046]. It is thought that these agents exert their toxic effects via generation of reactive oxygen species or ROS [Powis, G., Mustacich, D. and Coon, A. (2000), "The role of the redox protein thioredoxin in cell growth and cancer," Free Radical Biol. Med. 29, 312-322].
There are several known factors that prevent loss of muscle and adipose tissue. Insulin-like growth factor-1 (IGF-1) appears to play a key role in preventing muscle atrophy [Barton-Davis, E. R., Shoturma, D. I., Musaro, A., Rosenthal, N. and Sweeney, H. L. (1998), "Viral mediated expression of insulin-like growth factor I blocks the aging-related loss of skeletal muscle function," Proc. Natl. Acad. Sci. USA 95, 15603-15607]. However, during aging the muscle becomes unable to express the autocrine form of IGF-1 in response to mechanical overload resulting in reduced skeletal muscle function [Owino, V., Yang, S. Y. and Goldspink, G. (2001), "Age-related loss of skeletal muscle function and the inability to express the autocrine form of insulin-like growth factor-1 (MGF) in response to mechanical overload," FEBS Lett. 505, 259-263]. In addition, interleukin-6 (IL-6), a cytokine which plays a central role in inflammation, reduces both the level of circulating IGF-1 and the action of IGF-1 on muscle [Barbieri, M., Ferrucci, L., Ragno, E., Corsi, A., Bandinelli, S., Bonafe, M., Olivieri, F., Giovagnetti, S., Franceschi, C., Guralnik, J. M. and Paolisso, G. (2003), "Chronic inflammation and the effect of IGF-1 on muscle strength and power in older persons," Am. J. Physiol. Endocrinol. Metab. 284, E481-E487; De Benedetti, F., Alonzi, T., Moretta, A., Lazzaro, D., Costa, P., Poli, V., Martini, A., Ciliberto, G. and Fattori, E. (1997), "Interleukin 6 causes growth impairment in transgenic mice through a decrease in insulin-like growth factor-I," J. Clin. Invest. 99, 643-650]. Insulin and amino acids, particularly leucine, also seem to play a key role in preventing muscle loss by enhancing protein synthesis [O'Connor, P. M., Bush, J. A., Suryawan, A., Nguyen, H. V. and Davis, T. A. (2002), "Insulin and amino acids independently stimulate skeletal muscle protein synthesis in neonatal pigs," Am. J. Physiol. Endocrinol. Metab. 284, E110-E119; Anthony, J. C., Anthony, T. G., Kimball, S. R. and Jefferson, L. S. (2001), "Signaling pathways involved in translational control of protein synthesis in skeletal muscle by leucine," J. Nutr. 131, 856S-860S]. These, along with additional factors such as growth hormone, testosterone, and resistance exercise, increase metabolism as well as muscle growth and muscle strength [Yarasheski, K. E., Zachwieja, J. J., Campbell, J. A. and Bier, D. M. (1995), "Effect of growth hormone and resistance exercise on muscle growth and strength in older men," Am. J. Physiol. Endocrinol. Metab. 268, E268-E276; Ferrando, A. A., Sheffield-Moore, M., Yeckel, C. W., Gilkison, C., Jiang, J., Achacosa, A., Lieberman, S. A., Tipton, K., Wolfe, R. R. and Urban, R. J. (2002), "Testosterone administration to older men improves muscle function: molecular and physiological mechanisms," Am. J. Physiol. Endocrinol. Metab. 282, E601-E607].
Unfortunately, for many patients with debilitating diseases, many of the known therapies used to prevent the loss of muscle and adipose tissue are not ideal. IGF-1 and insulin levels may increase the risk of developing cancer and hypoglycemia after prolonged use. Similarly, growth hormone and testosterone have side effects that make them less than ideal. Nutrition-based therapies also do not significantly help maintenance of muscle mass and body weight.
There are several degenerative diseases of the skeletal muscle, including various forms of muscular dystrophy, that may be treated through transplantation of myoblasts and stem cells [Seale, P., Asakura, A., and Rudnicki, M. A. (2001), "The potential of muscle stem cells," Develop. Cell 1, 333-342]. Cell-based therapy may also be used to repair damaged skeletal muscle. However, as yet these procedures are limited by a short supply of myoblasts and stem cells and other technical difficulties including ensuring sterility of cell preparations. Therefore, promotion of survival of healthy cells and reversal of protein loss seem to be more viable strategies, particularly in combination, to prevent deterioration of healthy tissues in diseased and treated subjects.

Use of alkaline phosphatase to maintain healthy tissue mass in mammals


A lighting device capable of generating warm or neutral white light using blue light-emitting diodes (“LEDs”), red LEDs, and/or luminescent material that responds to blue LED emission is disclosed. The lighting device includes multiple first solid-state light-emitting structures (“SLSs”), second SLSs, and balancing resistor element. The first SLS such as a string of blue LED dies connected in series is able to convert electrical energy to blue optical light, which is partially turned into longer wavelength emission by the luminescent material. The second SLS such as a red LED die is configured to convert electrical energy to red optical light, wherein the second SLSs are connected in series. While the first SLSs and second SLSs are coupled in parallel, the balancing resistor element provides load balance for current redistribution between the first and second SLSs in response to fluctuation of operating temperature.

With decades of technical advancements and breakthroughs in the areas of semiconductor based solid-state light emitting devices, Edison's incandescent light bulbs, which typically have 30% or less light efficiency, will soon be replaced with energy-efficient light-emitting diodes ("LEDs"). A conventional LED is small and energy efficient with good lifetime. Various commercial applications of LEDs, such as homes, buildings, traffic lights, and electronic billboards, have already placed in service.
An LED is a semiconductor diode with a biased p-n junction capable of emitting narrow-spectrum light or electroluminescence. Color of emitted light typically depends on the composition of material used in the device. Color variations for visible light are usually defined by electromagnetic radiation or optical wavelengths from approximately 400 nm (nanometer) to 700 nm.
To generate white light, a conventional approach is to combine multiple emission wavelengths of LED sources (e.g., red, green, and blue LEDs) to produce desirable white light with various correlated color temperature (CCT). Alternatively, LEDs may be combined and/or added with luminescent material such as phosphors to convert at least a portion of LED emitted light to longer wavelength emissions to achieve a combined emission spectrum with white light of various CCT.
The quality of a white light source on color appearance of objects is usually measured by the Color Rendering Index ("CRI"), wherein the highest CRI rating is 100 when the alternative light source closely mimics the radiation spectral distribution of incandescent object at the same color temperature. Typical cool white fluorescent lamps, for example, have a CRI of 62. On the other hand, lamps having multiple component rare-earth phosphors can be constructed with CRI of 80 or better.
To enhance color appearance, a conventional approach is to mix blue LED(s), red LED(s) and some luminescent material that responds to blue emission in a package to generate warm or neutral white light. A problem associated with placing blue LED(s) and red (or orange) LED(s) in a same package is the color shift which is due to different temperature-dependent radiant (or luminous) flux drop as temperature drops. A factor that causes color shift is that the radiant (or luminous) flux drop between blue LED and red LED is different as operating temperature rises. For example, conventional indium gallium nitride ("InGaN") based blue LED chip and aluminum gallium indium phosphide ("AlInGaP") based red LED chip typically have different rate for flux drop in response to temperature change.

Method and apparatus for providing a passive color control scheme using blue and red emitters


In at least one embodiment, a data storage system includes a non-volatile memory array, such as a flash memory array, and a controller coupled to the memory array. The controller records, for each of a plurality of valid pages in the memory array, a respective indication of a dwell time of each valid page.

This disclosure relates to data processing and storage, and more specifically, to the recording and use of dwell time in a non-volatile memory system, such as a flash memory system.
Flash memory is a non-volatile memory technology that stores one or more bits of data per memory cell as a charge on the floating gate of a transistor. As cell densities and the number of bits stored per cell in flash memory continue to increase in subsequent generations of flash technology, the data stored in the memory cells to become more vulnerable to bit errors induced by read disturbs, high ambient temperatures, long storage durations and other factors. Consequently, the number of read/write cycles for which flash memories are rated have generally been declining even while storage density and cost per unit of data have been improving.

Recording dwell time in a non-volatile memory system

International Business Machines Corporation