A method for charging a lead acid storage battery to advantageously extend its life is described. The termination of a charging process is based upon an evaluation of the first derivative (dv/dt) and second derivative (d2v/dt2) of the applied charging voltage. By utilizing the first derivative (dv/dt) and second derivative (d2v/dt2) as charging criteria, an amount of overcharge is applied to the battery that takes into account the precise amount of amp-hours previously removed from the battery. A charger arrangement for performing a charging process of the invention also is described.

Rechargeable electric storage batteries of many different kinds are known, such as nickel-cadmium, nickel metal hydride, nickel-iron, lithium, silver-cadmium and deep-cycle lead acid batteries. Deep-cycle lead acid batteries differ from SLI (starting, lighting, ignition) lead acid batteries used, e.g., in conventional automobiles; SLI batteries are not designed or constructed to withstand repeated cycles of substantial discharge and recharge, and so are not rechargeable batteries in the sense of this invention.
It is known, such as from U.S. Pat. Nos. 4,392,101 and 4,503,378, that there are certain characteristics of a rechargeable battery, regardless of kind, which change during recharging of the battery in ways which signal either that the battery is fully charged or that it is at a relatively predictable point short of but near a state of full charge. Those patents, as well as other publications, describe equipment and techniques for monitoring those characteristics and for detecting certain events, conditions or states of them, and using such detections either to terminate the battery charging process or to continue charging for preset times or in preset ways. Those preset ways typically use charging processes different from those in use at the time of the detected event. Those charging event detection techniques are known as inflection analysis methods because they rely on the detection of certain inflection points in time-based curves which describe the change in battery voltage or battery current, e.g., during the charging process. While inflection analysis as described to date works well to control recharging of most kinds of rechargeable batteries, inflection analysis as heretofore described has been found not to serve satisfactorily for controlling recharging of flooded deep-cycle lead acid batteries in which the battery electrolyte is a liquid (typically sulfuric acid) unconfined in any supporting matrix such as a gel.
Flooded deep-cycle lead acid batteries are widely used as energy sources for electrically powered vehicles such as golf cars, fork lift trucks, and scissor lift vehicles. They also are used in uninterruptible power supplies in hospitals and other buildings and facilities, and as components of photovoltaic power installations. The reasons why inflection analysis techniques as heretofore described are not satisfactory for controlling recharging of flooded deep-cycle lead acid batteries can be understood from the use of such batteries in electric golf cars, as an example.
Electric golf cars are powered by sets of 4, 6 or so flooded deep-cycle lead acid electric batteries. At a given golf course, there is a fleet of such golf cars available for use by golfers. Different cars in the fleet may have older batteries in them than other cars in the fleet. Certain cars may be used more frequently than others. Some cars may be used longer on a given day than others. Some cars may be subjected to more strenuous usage conditions on a given day than others, depending on the circumstances of the using golfers or differences in traversed terrain, among other reasons. Also, it is well known that even if all batteries in the fleet are from the same manufacturer and are of the same nominal age, there still will be meaningful variations between batteries of kinds which can affect battery performance, life and, importantly, how they respond to recharging processes. As a consequence, at the end of a day when the golf cars in that fleet are to be recharged, there can be significant differences between the discharge states of the batteries from car to car, and consequent meaningful differences from car to car in how the batteries need to be charged. Fleet-wide uniform recharging procedures either will cause some batteries to be insufficiently recharged or, more likely, substantial numbers of the batteries will be materially overcharged. Material overcharge of such a battery reduces battery life. Very commonly, the persons employed to recharge fleets of golf cars have no understanding of the effects of substantial overcharge and how to determine when it is occurring. Therefore, it is desirable that the batteries used in electric golf cars be recharged by equipment and processes which avoid substantial overcharge and do so in ways which inherently accommodate and deal with differences between batteries due to discharge state, age, and manufacturing variations, among other factors.
Deep-cycle lead acid batteries are designed to withstand repeated cycles of substantial discharge from a fully charged state and of recharge from a discharged state to a state of full charge. As compared to other kinds of rechargeable batteries which do not use liquid electrolytes, the liquid acid electrolyte of flooded deep-cycle lead acid batteries presents special conditions which require that a given battery, or a given set of a small number of batteries repeatedly used in combination with each other, be recharged in a way which provides a controlled overcharge related in extent to the state of the battery at the time a recharge event is commenced. Stated differently, effective recharge of a flooded deep-cycle lead acid battery ideally should include a controlled overcharge determined by the amount of energy removed from (discharged by) the battery during its last preceding duty cycle (period of use following the last prior charging event). The reason is related to what happens to the liquid electrolyte during the prior duty cycle and the following recharge event.
As a cell of a lead acid battery discharges, the acid ions in the electrolyte move to the cell electrodes and oxygen atoms move from the active material of the cell into the electrolyte to form water with the electrolyte hydrogen ions. As a consequence, the electrolyte acid becomes progressively more diluted and its specific gravity progressively approaches 1.0 from a higher starting specific gravity. As the cell is recharged, that ion exchange process is reversed to produce regeneration of the electrolyte acid and the active material. If the electrolyte is present in the cell as a free liquid (i.e., the cell is flooded), as opposed to being present in a gel matrix, the regenerated acid, being heavier than the dilute electrolyte, sinks to the bottom of the cell as it is created. As the recharging process continues, more and more concentrated regenerated acid collects in the bottom of the cell. At the point at which the cell active material has been fully regenerated, the cell is theoretically fully recharged on a Coulombic basis. However, the cell is not in good condition for use to deliver stored electrical energy because of the stratification of the electrolyte. The electrolyte is not of uniform acidity throughout the cell and so the regenerated acid electrolyte is not in uniformly effective contact with the regenerated active material over the full area of the regenerated active material; if the cell were to be called upon to discharge at that point, the discharging electrochemical process will occur predominantly in the lower part of the cell where the electrolyte acid is overly concentrated. The cell will not discharge energy at the levels desired, and the over concentrated acid in the bottom of the cell will cause overly rapid degradation of the adjacent active material. The consequence is under performance of the cell in a manner which materially reduces cell life.
In the portion of the recharge process for a lead acid battery cell which immediately precedes full regenerative restoration of the active material, gas is generated in the cell as a normal part of the recharge process. The gas bubbles rise through the electrolyte to the top of the cell and, in the process, induce circulation (stirring) of the electrolyte in the cell. However, if the recharge process is terminated at the point of full regeneration of the active material, the amount of gas generation which will have occurred will be insufficient to stir the electrolyte adequately to cause it to be of uniform acid concentration (uniform specific gravity) throughout the cell. For that reason, it is common practice to continue the process of recharging a flooded deep-cycle lead acid battery beyond the point of full recharge, i.e., to extend the gas generation process for a time to achieve adequate stirring of the regenerated electrolyte. That is, the cell is intentionally overcharged.
Current practice is to overcharge such batteries, which include a number of cells, by a predetermined amount which is defined to be adequate to fully stir the electrolyte in the cell or cells which need the most stirring; that definition of the predetermined amount of overcharge is based on the assumption that the cell has been maximally discharged in its previous duty cycle and that the cell has certain properties of age, condition and temperature. However, as shown above in the discussion of the operation of a fleet of electric golf cars, that assumption is not apt for a substantial portion of batteries requiring recharge. As a result, reliance upon that assumption about the amount of overcharge to be applied in the terminal stages of recharging flooded deep-cycle lead acid storage batteries causes a substantial number, if not the majority, of such batteries to be meaningfully overcharged. Meaningful overcharge of such a battery, especially if repeated more than a few times, substantially reduces the effective life of such a battery.
The foregoing description provides a foundation for understanding how existing descriptions of inflection analysis techniques for controlling battery recharge processes are deficient when applied to the recharging of flooded deep-cycle lead acid storage batteries.
U.S. Pat. No. 4,392,101 is an early description of the use of inflection analysis in controlling recharging of rechargeable batteries. It teaches that rechargeable batteries in general have broadly similar response characteristics to recharging processes. It teaches that if battery voltage or current, e.g., is plotted graphically against time during recharge, the resulting voltage/time or current/time curves will have broad similarities. After initiation of the charge process, irrespective of the particular materials used to define a battery cell, those curves will manifest at least a pair of inflection points in which the graph line reverses curvature, i.e., is inflected. It is disclosed that those inflection points signal or denote different phases of the battery's response to applied charging energy and, for each type of cell, those inflections occur at relatively predictable times in the process, either before or at the time of the battery reaching a state of full charge. It is disclosed that the predictability of the inflection point occurrences is generally unaffected by (happens without regard to) factors such as the actual voltage of the battery, individual cell characteristics, individual charging history, or actual ambient temperature conditions. That patent discloses that the inflection points can be identified by observing the state or character of the first or second derivative with respect to time of the battery characteristic (voltage or current) being monitored. More particularly, it teaches that a graph of the second derivative will cross the zero axis (the sign of the derivative will change from positive to negative, or vice versa) at least twice during the charging process, and the second zero axis crossing of that derivative either will occur at the time the battery reaches fill charge or will occur at some interval shortly before fill charge is achieved. However, in the instance of lead acid batteries, that patent does not attempt to describe when the second time-based derivative of voltage occurs relative to full charge. The principal descriptions of that patent are in the context of nickel-cadmium batteries where recharging is terminated a preset time after that second zero-axis crossing of that derivative has been detected. Nickel-cadmium batteries do not use a variable density electrolyte which is present as a part of the chemical process and so such batteries do not benefit from or require any measure of overcharge.
U.S. Pat. No. 4,503,378 applies inflection analysis recharging controls to nickel-zinc batteries and discloses that, for that type of battery, recharging is to be terminated upon the occurrence of the second instance of sign change (zero axis crossing) of the second derivative of battery voltage with respect to time. It also observes that, at the same time as the second derivative crosses the zero axis from positive to negative, the value of the first derivative of battery voltage with respect to time is at a maximum or peak value, a fact which enables the second derivative's zero crossing to be confirmed.
The article titled "Charge batteries safely in 15 minutes by detecting voltage inflection points" appeared in the Sep. 1, 1994, issue of EDN Magazine. That article focuses principally upon fast recharging of nickel-cadmium batteries. It comments that inflection analysis also applies to lead acid batteries. In that connection, it states "In lead-acid batteries, the second dV/dt inflection occurs at a predictable interval before the batteries reach full charge, but from the battery's Ahr capacity rating, you can easily derive the duration of the incremental charging needed to achieve full charge." That statement does not contribute, for at least two reasons, to a solution to the problem of how to efficiently, reliably and effectively charge a flooded deep-cycle lead acid battery, without meaningfully overcharging it, in terms of the battery's true need for recharge. First, a lead acid battery's Ahr (ampere-hour) capacity rating is not a precise value which can be determined accurately from engineering information. Rather, it is a value which a battery manufacturer assigns to a model or type of battery as a result of business factors peculiar to the manufacturer, such as marketing objectives, warranty policies, and other factors. A battery's ampere-hour capacity rating is merely a manufacturer's statement of the expectable performance, perhaps under unspecified conditions, of an average battery of that kind or type. It has no reliable relation to the charging needs of a particular battery after completion of a particular duty cycle, i.e., its depth of discharge before experiencing a recharging event. Second, the ampere-hour capacity rating is a value which needs to be known from a source other than the battery itself. What is needed is a way to charge a flooded deep-cycle lead acid battery using information, derived from the battery itself, which describes the battery's discharge state and which is usable to overcharge the battery only enough to stir the regenerated electrolyte adequately.
Neither of the patents cited above nor the EDN Magazine article consider the state of battery discharge before a recharging process is commenced. They impart no knowledge about how information about that discharge state can be used to control recharge of that battery. However, apart from those descriptions it is known (such as from U.S. Pat. No. 6,087,805) to physically attach to a battery, such as a battery in a golf car, an integrating ampere meter (ampere hour meter) which travels with the battery at all times. When the battery is connected to a charger following the battery duty cycle, the "on board" ampere hour meter is connected to the charger so it can communicate to the charger the value of ampere hours removed from the battery during that last duty cycle. That information is applied in the charger to a computing and control device which computes the total charge to be delivered to the battery by multiplying the metered value of ampere hours by the desired factor (for example 1.10 or 110%)that has been found to produce sufficient stirring in the electrolyte. A computing and control device in the charger then monitors the ampere hours returned to the battery by the charger. When the calculated value for the charge return is reached, that computing and control device instructs the charger to terminate the charging process. While this approach is effective, it suffers from the added complexity of communicating data to the charger from the ampere hour meter which is associated with the battery. That approach also suffers from the added expense of equipping every battery, or every operational set of batteries, with its own captive ampere hour meter which must be specially constructed to survive in the environment of the battery. That approach is independent of inflection analysis and has apparent practical problems in the field.
It is apparent, therefore, that a need exists for the availability of equipment and procedures which can be used effectively, efficiently and reliably by persons having little or no knowledge of battery technology to adequately recharge flooded deep-cycle lead acid batteries without meaningfully overcharging any one or small group of batteries. Such equipment and procedures, to satisfy that need, should effectively address and conform to the actual recharge and electrolyte stirring needs of a battery or of a defined small group of batteries. The term "defined small group" means a number of batteries, such as those installed in a given electric golf car, which most probably will be of the same age, will have experienced the same usage history, and will have shared the same duty cycle in the interval between last being recharged as a group and the recharge event of interest.


A semiautonomously directed, autonomously controlled, gyroscopically stabilized, horizontal or vertical take off and landing (HOVTOL) flying apparatus employing two vertical lift devices equally and longitudinally spaced from the center of gravity of the apparatus; continuously integrated with a drive train apparatus, optional single or multiple power means; congruously connected thereto horizontal thrust devices. Integral to the vertical lift devices; pitch axis control devices situated at the exhaust orifices therein to vector said devices exhaust slip stream by a autonomous flight control system providing pitch stability. The autonomous flight control system providing continuously all flight control of the apparatus and said system being interfaced to a semiautonomous flight director device providing discrete flight direction function codes thereto. The combined effect of the apparatus is: When the power system rotates; coincident rotation of the drive train causes the vertical lift apparatus and horizontal thrust apparatus to counter rotate at right angles simultaneously providing both vertical lift and gyroscopic roll stability and simultaneously providing both horizontal thrust and gyroscopic yaw stability during flight; the continuous control thereof being accomplished by the autonomous flight control system and the directional steering, and function thereof in four axis effected by the semiautonomous flight director device which provides discrete flight function codes to the autonomous flight control system so as to disallow the initiation of negative flight maneuvers and/or functions providing for the safe unskilled pilot operation of the apparatus or any aircraft employing a autopilot having a autonomous digital flight control system.

Generally aircraft are divided into two major classifications, one is fixed wing and the second is rotary wing aircraft which are commonly referred to as helicopters. For purposes of substantiating the verity of the invention disclosed herein, comparing categories of prior art aircraft, the following to wit; (1) Wing fan lift aircraft (wing fan)--which are vertical take off and landing (VTOL) fixed wing aircraft that derive their vertical lift from fans, ducted fans, or propellers situated in their respective wings; (2) Tilt rotor/wing aircraft (tilt rotor/wing)--are fixed wing aircraft that have their propellers, rotors, ducted fans or jets situated at or near the tips of their wings or on the wings and said propellers, rotors, fans, wings, ducted fans, or jets are rotated ninety degrees to achieve VTOL flight transitions; (3) Jet assisted duct fans (jet assisted)--which are fixed wing VTOL aircraft employing jet engine or turbo fan engine thrust assisted fans or ducted fans. These aircraft have either their vertical lift augmented by jet or turbo fan thrust or the jet thrust is used to operate a vertical lift fan device in an enjoined manner; (4) Nozzle vectored jet thrust (jet thrust)--which are VTOL fixed wing jet aircraft that derive vertical lift from direct jet thrust channeled and directed by means of directional nozzles to achieve vertical lift and accomplish transitions; (5) Tail setters--a fixed wing VTOL aircraft that takes off vertically from an at rest vertical position standing on its tail and transitions to land the same way; whereby transitions are accomplished by rotating the entire aircraft ninety degrees to achieve VTOL transitions; (6) Various unusual VTOL aircraft.
The aviation industry has sought diligently to contrive an aircraft that can take off, land, and hover like a helicopter; without risk of stalling; and yet can also fly horizontally like a fixed wing airplane without the aerodynamic drag of a helicopter.
To date the closest that this goal has been met is with the Bell Helicopter V-22 Ospray VTOL aircraft. The V-22 is a fixed wing, tilt rotor, aircraft which takes off, lands, and hovers like a helicopter and rotates its' propulsion system 90 degrees to achieve horizontal flight like a fixed wing aircraft.
Other similar VTOL tilt rotor designs of prior art aircraft include the Bell Eagle Eye unmanned aircraft, Boeing Tracer Tilt Rotor unmanned aircraft, Bell XV-3, Curtis-Wright X-100 and X-19.
Tilt rotor prior art aircraft have five distinctive disadvantages. One is that the aircraft cannot land or take off horizontally like a conventional airplane if for some reason there was a failure of its' apparatus that rotates its' propulsion system while in the vertical flight mode. Another is due to their rotor diameters being so large that the rotors would strike the ground in a horizontal landing or take off scenario. Such a large rotor diameter is necessary however, in order for these aircraft to take off and land vertically.
The second disadvantage is that tilt rotor aircraft must overcome negative angular moments created by their spinning rotors when tilting their rotors 90 degrees during VTOL transitions. These forces act against the aircraft's fuselage creating a difficult control and stability phase for the pilot as the aircraft is transitioning in VTOL flight.
A third disadvantage of a tilt rotor aircraft is that they cannot fly at all if one engine should fail. The fourth disadvantage is one that is shared with helicopters in that tilt rotor aircraft, that do not employ jets or ducted fans, take a sizeable area to land in because of rotor diameter. A fifth disadvantage of tilt rotor aircraft, not employing jets or ducted fans, is also shared by helicopters which is exposed rotor blades that can strike nearby objects or people while landing and taking off.
Similar aircraft to the aforementioned are the U.S. ARMYS'/NASA Doak 16, the French NORD 500 and the Bell X-22; all are classed as tilt rotor aircraft in that the aircraft's propulsion systems are similarly rotated 90 degrees to achieve VTOL transitions. However, the X-22, the French NORD 500 and the Doak 16 employ ducted fans instead of rotors. This configuration allows the respective aircraft to land, take off, and hover like a helicopter and yet land and take off horizontally like a conventional fixed wing aircraft; they require less space in which to land and do not have exposed rotors.
The aforementioned tilt rotor ducted fan aircraft have two distinctive disadvantages. One is they likewise have negative angular moments acting against their fuselages to overcome when their respective propulsion systems are rotated 90 degrees during VTOL transitions. The second disadvantage is that they use ducted fans which, when employed in horizontal flight, limits their forward speed. The forward speed limitation of ducted fans is due to the fact that they build up a boundary layer of air immediately in front of the ducts at higher forward air speeds. This limits their forward airspeed to that of helicopters thus limiting their application on VTOL fixed wing aircraft.
Another type of VTOL aircraft known as tilt wing aircraft; as opposed to tilt rotor/ducted fans; are not true fixed wing aircraft. A few of the more well known tilt wing prior art aircraft are: The army/Navy VERTOL Model 76; the LTV/Hiller/Ryan XC142, which was based on the Hiller X18; and the Candair CL-84. These tilt wing aircraft, as the designation implies, tilt their wings 90 degrees with the propellers and engines attached to the wings to achieve VTOL flight transitions. However, they are generally accepted to be VTOL fixed wing aircraft as the wing is in a fixed position during horizontal flight.
Notwithstanding the moveable wing, they do take off and land, as well as hover, like a helicopter and transition to fly horizontally like an airplane. As with tilt rotor and tilting ducted fans, as aforementioned; tilt wing aircraft have to also overcome inherent negative angular moments when their wings are rotated 90 degrees to achieve VTOL flight.
Another problem with tilt wing designs is that the chance of a stall is greater than with tilt rotor or tilting ducts as tilt wing aircraft have a greater difficulty attaining aerodynamic lift on their wings for horizontal flight during part of the transition phase of VTOL flight.
Yet another type of fixed wing VTOL aircraft, known as tail setters, rest on their respective tails, vertically, and take off and land vertically on their tails. To achieve horizontal flight the entire aircraft rotates 90 degrees during VTOL flight transitions. The most notable of this type of prior art aircraft are the Convair XFY1 Pogo, the Lockheed XFV1, and the McDonnel Douglas Sparrow Hawk unmanned aircraft and the Bell X13 Vertiplane.
The most important short coming of tail setter VTOL fixed wing aircraft is the same as that of the tilt wing aircraft with respect to a lack of aerodynamic lift of the fixed wing during VTOL transitions and also having to overcome negative angular moments created by the gyro effect of their spinning propellers when rotated longitudinally from the angle of attack of the aircraft. The one exception being the Bell X13 Vertiplane which employed a jet engine. An additional; yet the most notable; draw back of a manned tail setter was a lack of pilot situational awareness during VTOL transitions.
Other examples of fixed wing VTOL aircraft employ vectored jet engine thrust as a means of providing vertical lift to hover and achieve VTOL flight.
The most notable of this type of prior art aircraft is the British harrier jet aircraft. These type of VTOL aircraft use the thrust of their jet engines vectored by rotating nozzles to accomplish VTOL flight and transitions.
Jet thrust type VTOL fixed wing aircraft have four notable drawbacks in that their jet engine thrust is of such a great magnitude that foreign objects kicked up by the jets tremendous thrust blast create hazardous conditions to both the aircraft and personnel on the ground near the aircraft's landing zone during VTOL landings and take offs. A second draw back is that in order for the aircraft to hover or take off vertically the aircraft's engines must be at or very near full throttle.
For a jet engine aircraft to accomplish hover flight and VTOL flight with full throttle, a tremendous amount of fuel is required thus diminishing the aircraft's horizontal flight time and range. The third disadvantage is the cost of providing such an aircraft due to the complexity of providing hover flight stability and the cost of a specialized jet engine for vertical flight.
Additional examples of employing jet thrust for vertical lift are disclosed in U.S. Pat. No. 3,972,490 issued Aug. 3, 1976 to Vincent H. Zimmermann et al and U.S. Pat. No. 4,171,112 issued Oct. 16, 1979 to Harry M. Harvy of England. The aircraft of U.S. Pat. No. 3,972,490 is a hybrid version combining nozzle vectored jet thrust together with a single ducted fan. This concept is similarly disclosed in U.S. Pat. No. 5,290,428 issued May 11, 1993 to Paul M. Bevilaqua and Paul K. Shumpert. A variation to the aforementioned aircraft is disclosed in U.S. Pat. No. 3,912,201 issued Oct. 14, 1975 to Charles Bradbury of England.
A variation of the above VTOL fixed wing aircraft is depicted as employing a combination of jet thrust and ducted fans as disclosed in U.S. Pat. No. 2,940,691 issued on Jun. 14, 1960 to Constant V. David, and U.S. Pat. No. 3,161,374 issued on Dec. 15, 1964 to Robert W. Allred et al. These last two prior art aircraft have one thing in common in that they both have their vertical lift fans in their wing area. These types of configurations, employing lift fan wings, create a distinctive draw back as will be discussed in the following aircraft prior art disclosures.
A classification of fixed wing VTOL aircraft, generally accepted as being known as lift fan wing aircraft, derive their vertical lift from fixed immovable ducted fans or propellers situated inside the wing area of the aircraft. These aircraft have one distinctive characteristic among them. The area of their wings displaced by the in wing fans severely limit the wings horizontal flight lifting capability due to drag.
The drag of a lift fan wing results from thicker wings required to accommodate the fans and a reduction of wing lift due to the slip stream air over their wings in horizontal flight being disturbed while the fans are in operation.
The only known in the wing lift fan aircraft to work operationally is the Ryan XV-5A and the Lockheed Hummingbird; both are similar to the prior art aircraft disclosed in U.S. Pat. No. 3,080,137. These concepts augment the in wing lift fans' lift by piping jet thrust to them. Another in the wing lift fan aircraft, that was to also augment its' lift by piping jet thrust to their fans, is disclosed in U.S. Pat. No. 3,161,374 but never known to fly.
Other in the wing lift fan concepts of prior art are disclosed in U.S. Pat. Nos. 2,939,649; 3,083,935; 4,125,232; 3,120,362 and 4,828,203; none of these concepts have been known to fly as of the date of this application.
Two prior art concepts disclosed in U.S. Pat. No. 3,559,921 issued Feb. 10, 1967 to Eugene L. Timperman, and U.S. Pat. No. 2,138,999 issued Dec. 6, 1938 to Wilmer W. Clark, show their vertical lifting apparatuses situated in the center body of the aircraft which is similar to the aircraft of U.S. Pat. Nos. 5,209,428; 3,912,201; 2,939,649 and U.S. Pat. No. 2,988,301 issued on Jun. 13, 1961.
In the Timperman patent, a single ducted fan is situated in the center of the aircraft's fuselage for vertical lift and driven by two engines; one in the front of the aircraft and one engine in the aft section of the aircraft. A transmission forward of the ducted fan transfers power to two wing mounted propellers for horizontal thrust.
Like the aircraft disclosed in U.S. Pat. No. 3,912,201; Timperman's aircraft employs thrust from the ducted fan piped to various locations of the aircraft to provide stability while in hover.
The departure of U.S. Pat. No. 3,912,201 from the Timperman disclosure is that the fans thrust is not augmented by jet thrust as is the case in U.S. Pat. Nos. 5,209,428; 3,912,201; and 2,939,649.
Without augmented thrust from some other source, a single ducted fan, proportionally shown in the Timperman disclosure, can not lift such an aircraft vertically according to current technology. However, such a concept could prove to be effective as a short take off and landing aircraft.
The prior art disclosed by Wilmer W. Clark in U.S. Pat. No. 2,138,999 discloses a vacuum lift device that is purported by the inventor to operate on vacuum forces and differences in atmospheric pressure principals that supposedly create a lifting force of several tons with two three foot diameter by three feet deep pressure differential devices.
While the Clark concept is intriguing, the disclosure was made far in advance of actual ducted fan research performed some 20 years later which has subsequently shown that the vacuum lift device is not technologically feasible as disclosed. Indeed, the vacuum lift device, so disclosed, does not have an open bottom; a physical requirement of any ducted fan. The device produces no thrust for vertical lift. It should be evident to the most casual observer upon reading the text of the Clark patent, that generating thrust was not Clark's intent.
The devices disclosed in Clark's aircraft is constructed similar to a modern day washing machine tub and agitator. The agitator is substituted by a multi-blade propeller having a three foot diameter, a three foot cord, and each blade being twisted about their ax's.
The Clark propellers rotate radially in an enclosed tub that is open only at the top. The Clark disclosure is not predicated on any known physical laws or principals as of the date of this application.
Unusual VTOL flying bodies that can not be classified as fixed wing aircraft nor helicopters are represented by the Sikorsky Cypher, the Canadair CL-227 Sentinel, and the General Dynamics Ring Wing Vehicle (RWV) among others; all three disclosed herein are unmanned aerial vehicles (UAVs). The Cypher UAV has a doughnut shaped fuselage with two contra rotating, articulated, rotor blades similar to a configuration used by some helicopters. The blades are situated within the center opening of the doughnut shape fuselage connected by a gear box and drive shaft which is situated at a fixed radius position laterally connected to a power means in the fuselage. The primary advantage of the Cypher is that it does not have exposed rotor blades and can land and take off like a helicopter.
However, the Cypher UAV has several disadvantages. One disadvantage is that the craft hovers all the time. Therefore, it must expend fuel at a higher rate than that of a helicopter or an airplane as little lift is afforded the craft in horizontal flight. As a result of not having wings, the craft suffers a secondary disadvantage of severe controllability problems in horizontal flight. These two draw backs lead to a third disadvantage which is limited range for its' rated flight duration. The combined aforementioned disadvantages also limit the crafts' forward speed. Because the craft hovers all the time it suffers a low maximum altitude rating compared to that of other VTOL flying bodies and aircraft of proportionate size and weight. The Cypher is further disadvantaged by its design in that it has a very low payload carrying capability disproportionate to its' Reynolds class. Having no control surfaces, this aircraft is lacking in aerodynamic directional steering in forward flight.
A prior art aircraft similar to the aforementioned Cypher UAV, is the CL-227; having a somewhat like manner in providing vertical lift in that it has two articulating contra rotating rotors.
The CL-227s fuselage is elongated vertically with the power means in the center of the craft. The overall aircraft resembles the likeness of a flying peanut for which it has been nicknamed. The craft lands and takes off vertically like a tail setter VTOL aircraft/UAV and hovers all the time like the Cypher UAV. One advantage the CL-227 has over the Cypher prior art aircraft is that it is somewhat more controllable in direction during forward flight because its' rotors are exposed to the surrounding slip stream air which provides the craft with some ability, via the articulation of its exposed rotors, to control its direction by the action of slip stream air against its' rotor blades which act as control surfaces during forward flight.
The CL-227s exposed rotor blades excludes its' use in UAV commercial application authorization by the FAA. The CL-227 UAV has virtually the same disadvantages of the Cypher UTAV with the exception of controllability and payload carrying capability.
Like the CL-227 UAV prior art aircraft the General Dynamics Ring Wing Vehicle (RWV) is a VTOL UAV that lands and takes off on its tail like the earlier mentioned prior art tail setter aircraft. The RWV however, employs a ducted fan configuration employing thrust vectoring for directional control. The craft takes off vertically and then rotates its entire fuselage ninety degrees for horizontal flight applications, unlike the Cypher and CL-227 prior aircraft art, with landing being the reverse of this action. In horizontal flight mode, the duct of the ducted fan itself provides lift for the vehicle in horizontal flight and functions as a ring winged aircraft.
While the General Dynamics RWV UAV has no exposed rotor blades, a distinct advantage in commercial UAV applications, it must however, resolve the difficult flight dynamics of negative angular moments like tilt wing and tilt rotor prior art aircraft and the flight dynamic problems of the tail setter prior art aircraft limiting its' use in commercial applications as a UAV because of safety issues involving pilot situational awareness and controlling the craft during VTOL transitions.
A configuration entailing some of the attributes of the Cypher, and some from the RWV aforementioned prior art aircraft, is the manned VZ-9V Avrocar aircraft. Built under a Canadian and U.S. Army/Air Force contract, this prior art aircraft is similar in design to that of a fictional flying saucer. The craft is disk shaped and employs three jet engines for power.
A single ducted fan is situated in the center of the VZ-9V and used as the primary vertical lifting means. The ducted fan is powered by the jet engines. Control and forward motion of the craft is accomplished by thrust vectoring the three jet engines' thrust. The craft suffered from such extreme controllability problems however, that the project was cancelled.
The Piasecki Air Jeep is an example of unusual prior art aircraft that was developed and flown under US Army/Navy contracts between 1957 and 1962. The craft was constructed having a dual power means located at the center of its' fuselage. The power means drove a central gear box, likewise centrally located, which entailed a hydrostatic drive means. The hydrostatic drive means drove two, variably pitched, horizontally mounted, counter rotating, vertical lifting propeller means; one situated in live rear of the fuselage and one in the forward section thereof. Both propellers are shrouded by the crafts' fuselage.
Partial control stability and forward motion of the Air Jeep was accomplished by thrust vectoring. The thrust vectoring means is comprised of a series of thrust vectoring vanes concentrically and evenly situated around the exhaust orifices of the vertical lifting means in a star configuration. Roll, pitch, and yaw control was accomplished by a combination of articulation of the vertical lifting propellers in conjunction with the thrust vectoring vanes. This prior art craft had a number of disadvantages. As the craft hovered all the time, its' range was limited; a result of excessive fuel consumption. The craft derived all of its' forward motion from its' vertical thrust thus limiting its' forward speed. As the craft employed shrouded propellers as opposed to true ducted fans, no inherent gyroscopic roll control was effected due to the lower rotational speeds required of larger diameter shrouded propeller applications versus the higher rotational speeds allowed by the smaller diameter of a ducted fans' rotors.
Likewise, a disadvantage of the crafts' employment of shrouded propellers is that the diameter normally required in such vertical lift applications generally preclude its' application in a fixed wing aircraft due to the disproportionate width of the fuselage required to accommodate the large propeller diameter. Such a wide bodied fuselage would create a significant drag problem as to be efficiently applied to a fixed wing aircraft application. In a true ducted fan application however, duct depth and diameter as a function of its' blade chord, diameter, and number of blades employed, combine with higher rotational speeds to allow greater thrust in a smaller area over that of a shrouded propeller; this allows for a narrower more aerodynamic fuselage. An additional disadvantage of this prior art craft is the drive means, being hydrostatic, is complex and heavier than a direct drive design. This example of prior art drive train means did not lend itself to adding a horizontal thrusting means.
The Air jeep employed twin engines for a one engine out safety feature at low altitudes. A single engine failure at a moderate altitude however, was sufficient to terminate its' flight even with the remaining engine functioning. The craft can not auto rotate like a helicopter for a safe landing. Lacking wings, and horizontal thrusting means, it could not land horizontally like a twin engine fixed wing aircraft with a remaining engine functioning.
In regard to the prior art apparatuses respecting the Semiautonomous Flight Director device (SFD) invention disclosed herein; all require a skilled pilot. To one degree or another each prior art apparatus either augments skilled pilot operation directly, or affords a skilled pilot a means to better utilize a autopilot.
Flight control and situational awareness and the lack thereof for UAV pilots is of particular concern to UAV manufacturers and users alike, most specifically military and non-military government users. As of the date of this application over eighty five percent of all UAVs currently being flown in the world today will crash as a result of a UAV pilots' lack of situational awareness and the resulting loss of flight control over the UAV flown regardless of any given UAV pilots' skill and/or experience level. These two factors alone, according to current UAV mishap statistics, are of paramount importance to the Federal Aviation Agency (FAA) and the National Transportation -and Safety Board with respect to their authorization for use and implementation of UAV technology in the civilian and commercial aviation sectors.
Disclosed in U.S. Pat. No. 5,255,880 issued Oct. 26, 1993 to Woon Lyloc and David C. Pattison is a manual override apparatus which allows a skilled pilot to override autopilot operation in aircraft that have fly by wire or fly by light flight control systems as opposed to mechanical flight control systems having an autopilot system.
In this prior art device the pilot does not have to disengage the autopilot in order for a skilled pilot to make direct changes to the controls that are under direct autopilot command. The degree of change made by the action of a pilot displacing a given aircraft's manual control stick or yoke is sensed by a circuit when the pilot places a specific amount of force on the control stick or yoke. Once the amount of force level reaches a certain threshold, the amount and degree of deviation, in linear terms, of the pilots' control stick or yoke is subsequently sensed to allow a pilot to make flight control changes under autopilot command but only to the exact degree of deviation made in the pilots' control stick or yoke.
It is important lo note here, that in the application of this prior art device; only a skilled pilot having knowledge and sufficient skill in flying a particular aircraft under non-autopilot operation should make such deviations in the control stick or yoke of such an aircraft having the device and autopilot. The reason for this is that the amount of deviation made in the pilots' control stick is directly related and linearly proportionate to the amount and degree of linear and proportional change effected in the flight controls of the particular aircraft flown by the pilot.
This is to say that a pilot could place the control stick into a position and to such a degree that would cause the flight controls of the aircraft flown under autopilot command to likewise place said aircraft in a negative flight regime. This could result in the loss of aerodynamic control of the aircraft if it were not for the pilots' skill precluding the placing of the control stick in such a position as to cause a negative flight regime.
The advantage of the prior art device is it allows override control of the autopilots' flight controls of a aircraft having a fly by wire or fly by light flight control system whereby a skilled pilot may make changes directly to the flight controls coincident to direct command of an active autopilot governing said aircraft flight controls.
A disadvantage of this prior art device is that it is not applicable to aircraft having flight control systems other than fly by light or fly by wire flight control systems and the system requires operation by a skilled pilot.
U.S. Pat. No. 5,067,674 issued Nov. 26, 1991 to Albert Heyche, Alain Latteur, and Philippe Dekoninck, all of Brussels Belgium, discloses a control system for remote controlled aircraft, which is, in effect, a compensator for variations of time lags associated with the difference in time from the moment a pilot initiates an action by remote control until the aircraft in flight begins to act on the change with respect to the aircraft's resultant attitude change that follows the execution of the various interactions of the aircraft's flight control surfaces.
It is further disclosed in U.S. Pat. No. 5,067,674 that the device automatically compensates for variations in normal operation of a flight control system of a remotely controlled helicopter to prevent negative flight regimes. The prior art device aids, in an automatic manner, a skilled pilot in piloting a remotely controlled helicopter. The system does not however, supplant the skill normally required to pilot a remotely controlled aircraft or helicopter.
U.S. Pat. 4,964,598 issued Oct. 23, 1990 to Zacharaia Berejik, Ramot Tzahala; Allon Wallach, Moshav Talmei Elazar, of Israel discloses an apparatus to automatically stabilize, to a certain degree, a remotely control aircraft in yaw and roll for aircraft turns initiated by a pilot whereby the aircraft is required to bank in order to accomplish the turn.
The apparatus, also in like manner, provides automatic stabilization, to a certain degree, of the pitch of a remotely controlled aircraft for aircraft ascensions and descentions initiated by the pilot.
The apparatus however, does not supplant pilot skill, but rather is an aid to a skilled pilot that automatically compensates to a certain degree for the pilots' lack of situational awareness of the difference between what a pilot perceives to be the actual attitude of a remotely controlled aircraft versus the actual physical attitude of the remotely controlled aircraft when performing certain flight maneuvers. The apparatus does not preclude the pilots' placing the aircraft in a negative flight regime however.
The apparatus allows a skilled pilot to perform flight maneuvers that include negative flight regimes in order to allow a skilled pilot to accomplishacrobatic like flight maneuvers in such a way as to compensate to a limited degree for the lack of the pilots' situational awareness of the actual physical attitude of the remotely controlled aircraft with respect to the pilots' perception of the aircraft's attitude.
U.S. Pat. 4,642,774 issued Feb. 10, 1987 to John P. Ceyntala and Kenneth W. McElreath of Iowa is similar in function to the apparatus earlier mentioned herein and disclosed in U.S. Pat. No. 5,255,880.
The apparatus allows a pilot to make manual flight control deviations under autopilot control and then subsequently return to autopilot control of the aircraft to allow the autopilot to smoothly return to the autopilots' preprogrammed flight regime, or optionally, to a new program set determined by the manual flight control deviations initiated by the pilot.
The primary effect of this prior art device is in allow for over ride changes in an autopilots' control of an aircraft by a pilots' degree of linear displacement of the pilots' control stick either allowing the autopilot to return to its' preprogrammed flight path or alter the preprogrammed flight path in accordance with the degree of linear displacement of the pilot's control stick.
All actions therefore, being accomplished in such a way as to make flight control changes without abrupt flight dynamics resulting from the change initiated by the pilot. Both of the aforementioned prior art devices and the aforesaid prior art device disclosed in U.S. Pat. No. 5,255,880 require a skilled pilot versed in the manual flight operations of the particular aircraft flown and so equipped with said devices so as to preclude the manual placement of the pilots' control stick in such a positions as to cause a negative flight maneuver being initiated by the autopilot.

Horizontal and vertical take off and landing unmanned aerial vehicle


A production equipment line for a hot-rolled steel strip comprises a rough rolling mill group comprised of plural rough rolling mills for hot rolling a material which is heated up to a predetermined temperature to a finish rolling start sheet thickness and a finish rolling mill group comprised of plural finish rolling mills for controlled-rolling the material to a final sheet thickness, wherein at least one of the plural rough rolling mills is a reversible rolling mill. The production equipment line for a hot-rolled steel strip is provided with a slow cooling apparatus for slowly cooling the material at a water volume density of less than 1000 L/min·m2 and a rapid cooling apparatus which is arranged next to the slow cooling apparatus and rapidly cools the material after the slow-cooling at a water volume density of not less than 1000 L/min·m2.

FIG. 1 shows a general hot rolling process. In this rolling process, a material to be rolled (slab) heated to about 1200° C. through a continuous heating furnace 1 is first forged in a widthwise direction by a sizing press 2 to adjust a sheet width and then rolled by a rough rolling mill group 3 to form a sheet bar 10 having a thickness of 30-50 mm, and subsequently the sheet bar 10 is rolled by a finish rolling mill group 6 having 6-7 stands capable of performing continuous rolling up to 1.2-25 mm to obtain a rolled steel strip, which is then cooled by a runout table 7 and coiled by a coiler 8.
Since hot-rolled steel strips have hitherto been frequently used in press working, workability such as formability or the like has been considered to be important. In recent years, they has been used as a structural steel sheet represented by a linepipe or the like, so that strength and toughness are frequently required. The structural steel sheet is very thick having a thickness of 8-25 mm among the hot-rolled steel strips and particularly has a thickness of not less than 12 mm as a raw material for a linepipe. In order to increase the strength and toughness, it is advantageous to perform a controlled-rolling (CR) in the production process of the hot-rolled steel strips. The controlled-rolling has been mainly performed in the production process of thick steel plates since long ago and is a technique of increasing the toughness by rolling at a low temperature zone, where the crystal grain growth rate of steel is slow, to make crystal structure fine.
In general, a temperature for starting the controlled-rolling differs in accordance with an additive element such as Nb, V or the like and is roughly not higher than 950° C. The controlled-rolling is conducted at a rolling reduction of about at least 60% from a controlled-rolling start thickness to a product thickness. For example, when the controlled-rolling is performed at a rolling reduction of 60%, the controlled-rolling start thickness is about 30 mm in the case that the final thickness of the hot-rolled steel sheet is set to 12 mm, while the controlled-rolling start thickness is about 63 mm in the case that the final thickness is set to 25 mm. In the production process of a usual hot-rolled steel sheet, when the final thickness is set to 25 mm, there is adopted a method wherein rough rolling is first conducted to render a sheet thickness of a sheet bar into 63 mm until the end of the rough rolling and then the sheet bar is air-cooled while waiting before a finish rolling mill group 6 until a central temperature of the sheet bar arrives at not higher than 950° C. and thereafter rolled in the finish rolling mill group 6. In this case, the waiting time of the sheet bar before the finish rolling mill group 6 is required to be about 200-300 seconds, during which time a next material cannot be rolled, so that the rolling efficiency is largely decreased. As to the production line of the hot-rolled steel strip, there are only a few prior art documents for solving the above problems, but many examinations are made in the production line of thick steel sheets, and the following techniques are disclosed for example.

Production equipment line for hot-rolled steel strip and production method for hot-rolled steel strip


A tool for assessing rotatable objects in an engine by selectively imparting a rotation to a chosen number of the rotatable objects that includes an engagement member, a shaft portion, and a motor as a rotation source. In the preferred embodiment, the engagement member mounted on a first end of the shaft engages the rotatable object. A support member means is mounted on a second end of the extendable member or on the shaft. A rotation source is used to impart rotation on shaft and engagement member and thus to the rotatable object to be rotated as may be required to facilitate for the testing and adjustment procedures to be performed upon the rotatable member.

The disclosed tool is used to engage a selected, rotatable object encountered by those working on machinery. Often, these rotatable objects are difficult to selectively rotate. For example, in an automobile engine, a pulley may need to be rotated to identify which individual pulley is failing or exhibiting signs of failure. However, these pulleys are difficult to reach, are interconnected by belts and are not independently powered. Therefore, it is very difficult to independently test each pulley. Currently, one must attempt to either have the engine running and thus powering all the connected pulleys or attempt to rotate the pulleys by hand. The first approach causes the pulleys to rotate at operational speeds but confounds identifying a specific problem due to noise and movement from the engine and other components. In addition, it is dangerous as the person attempting to identify the problem must do so near or even touching a motor in operation. The second is difficult because operation speeds cannot be reached, and it often is difficult to reach the pulleys themselves in confined spaces.


A method for manufacturing semiconductor devices according to this invention, comprises the wafer manufacturing step of forming an integrated circuit with a redundant circuit in each of a plurality of chip areas on a semiconductor wafer and also forming at least one stress testing terminal that applies a stress testing voltage or stress testing signal to the interconnections other than those for power supply in the integrated circuit for each of the chip areas or for every certain number of the chip areas, the step of, after the wafer manufacturing step, screening failures by applying a specified stress testing control signal or stress voltage to a certain number of chip areas with the stress testing terminal in contact with a contact terminal of a tester in the wafer state, the step of, after the screening step, judging whether or not the electrical characteristics of each chip area are acceptable through die sort test, the step of remedying an integrated circuit in a chip area judged to be defective in the judging step, by means of the redundant circuit, and the assembly step of, after the remedying step, separating the chip areas into individual elements and then assembling them into an integrated circuit device.

1. Field of the Invention
This invention relates to a method for manufacturing integrated circuit devices or wafer-scale integrated circuit devices, and more particularly to a method for manufacturing semiconductor devices with stress applying means for applying a more increased voltage stress than during normal operation in screening failures in the wafer state.
2. Description of the Related Art
Before the shipment of semiconductor devices, screening is generally performed to ensure their reliability in a manner that exposes and removes possible defective devices with the aim of preventing acceptable devices from unreasonably deteriorating or failing after delivery. For screening methods, burn-in that realizes the acceleration of both electric field and temperature at the same time is widely used. In the burn-in process, a device is operated at a higher voltage than its actual operating voltage at a higher temperature than its actual operating temperature to apply to the device a higher stress than that during the initial failure period of time under actual operating conditions, with an eye to screening out devices that would probably cause initial operating failures before shipment. In this way, possible initial-failure devices can be removed efficiently, thereby increasing the reliability of products.
In DRAMs of today, a raised potential (for example, in the vicinity of 1.5.times.V.sub.CC) is applied to the gate oxide film of the transfer gate (referred to as the cell transistor) of a memory cell during cell transistor selection, with the result that a severe electric field is applied to the oxide film even if it is thick. This can create a reliability problem. Therefore, in placing DRAMs under burn-in conditions, it is necessary to perform a positive screening of cell transistors whose gates are applied with a raised potential.
A conventional method used for screening of cell transistors in the burn-in process of DRAMs is to scan the addresses so as to sequentially access the word lines connected to the gates of those cell transistors. In this method, a voltage stress is applied to the cell transistors much less frequently than the transistors of the peripheral circuitry, which results in a short-time exposure of the cell transistors to the maximum electric field. Therefore, the burn-in process of such cell transistors requires a long time.
To solve the problem of applying a voltage stress to cell transistors less frequently as noted above, one of the inventors of this application has disclosed a semiconductor memory capable of improving the efficiency of applying stress to cell transistors in Published Unexamined Japanese Patent Application (Kokai) No 3-35491 which is issued to T. Furuyama and which corresponds to U.S. Pat. No. 5,258,954. In this semiconductor memory, for screening of defects, a voltage stress is simultaneously applied to all word lines or more word lines than those selected during normal operation, which is effective especially for the burn-in process in the wafer state.
In the above proposal is applied to a DRAM, defective cell transistors can considerably be reduced and 1M or 4M DRAMs having bit defects can be decreased at high speed by the screening. Therefore, the screening can be greatly improved in efficiency.
In the manufacture of EPROMs that use two-layer gate MOS transistors with a floating gate as nonvolatile memory cell transistors, the functional test includes the process of testing the charge-retaining characteristics of the floating gate of each cell transistor (the threshold voltage characteristics of cell transistors). In the test, after data (program) is written into all the cell transistors of the EPROM, voltage is applied to the gates of all those cell transistors simultaneously. This technique is disclosed in U.S. Pat. No. 4,779,272, issued to Kohda, et al. on Oct. 18, 1988 and U.K. Patent Application GB 2053611A, issued to Vernon Geroge on Feb. 4, 1981. The above functional test requires the monitoring of the properties of an EPROM, including current and voltage, and is different from the above-described burn-in process that causes the device to experience more severe stress than during the initial failure period of time under actual operating conditions.
In the manufacture of semiconductor devices with stress applying means for applying a more accelerated voltage stress than in normal operation, including the aforementioned semiconductor memories, the burn-in step in the wafer state should be added if necessary, taking into account the streamlining of the entire manufacturing process.

Method for testing semiconductor devices


A hollow article is molded in a state where an inner surface of a neck portion including an inner screw portion is held by an inner neck mold, and then, the hollow article is demolded from the inner neck mold by inserting an ejection rod into the hollow article to be engaged with an inner surface of the hollow article and rotating the hollow article together with the ejection rod.

Conventionally, for example, many containers containing beverages or the like have a screw portion (outer screw portion) on an outer surface (outer side) of a neck portion thereof, and are closed by a cap mounted on the outer side of the neck portion having the outer screw portion. Further, there are not only containers which include the outer screw portion, but also containers which include a screw portion (inner screw portion) on an inner surface (inner side) of a neck portion and are closed by a cap mounted in the neck portion.
In addition to containers, some of various hollow articles having a space inside have an inner screw portion formed on an inner side of a neck portion thereof. Since the inner screw portion is a so-called undercut, it may be difficult to demold the neck portion from a mold that forms the inner screw portion when molding the hollow article including the inner screw portion.
A hollow article such as a container is formed by, for example, forming a preform by injection molding and then blow molding the preform. In this case, the inner screw portion of the neck portion is formed when injection molding the preform. Although the neck portion may be demolded after the injection molding of the preform (before the blow molding) from a mold by which the inner screw portion is formed, the neck portion may be demolded after the hollow article is formed by the blow molding from the mold by which the inner screw portion is formed (see, for example, Patent Literature 1).
The invention disclosed in Patent Literature 1 employs a neck mold having an inner and outer double structure including an outer neck mold that forms an outer surface of a neck portion and an inner neck mold that forms an inner surface of the neck portion including an inner screw portion. When injection molding the preform, the neck portion including the inner screw portion is formed, and the preform is blow molded in a state where the inner surface of the neck portion is held by the inner neck mold to form a container that is a hollow article. Thereafter, a roller is abutted against a body portion of the container to rotate the container, that is, the container itself is rotated, thereby demolding the neck portion from the inner neck mold.
By adopting such a method to demold the neck portion from an inner core mold, the hollow article such as the container can be successfully demolded from the inner neck mold while preventing deformation of the inner screw portion.

Hollow article molding method and molding apparatus and hollow article


To provide an apparatus that may impart a complicated bend deformation to an object to be machined such as a ceramic bar elongated in one direction or the like, and may reduce the non-uniformity in machining amount of the object to be machined upon the machining work of the object to be machined, specifically a correcting mechanism for deforming the object to be machined together with a jig holding the object to be machined is provided in a machining apparatus. The correcting mechanism includes a base, a plurality of levers provided at first ends with pins, a shaft fixed to the base for rotatably supporting the levers, and a plurality of correcting drive means coupled to second ends of said levers for pivoting the levers to the shaft to thereby pivoting the pins. The jig includes a plurality of load receiving portions arranged in a holding portion elongated on one direction for holding the object to be machined whereby portions corresponding to the load receiving portion in the holding portion are deformed together with the object to be machined in accordance with pivoting of each pin.

1. Field of the Invention
The present invention relates to a polishing machining apparatus and a machining method for machining a workpiece to be polished where a plurality of magnetic heads are arranged, and more particularly to an apparatus and a method for correcting a bend of the workpiece during the machining work.
2. Related Background Art
A thin film magnetic head to be used in a magnetic disc apparatus or the like is composed of parts obtained by machining a rod-shaped ceramic (hereinafter referred to as a ceramic bar) where a number of element parts made of a magnetic thin film or the like forming induction type magnetic converting elements, magnetic resistors (hereinafter referred to as MRs) elements or the like are formed in a line on a surface. Conventionally, in a batch type manufacturing process of parts for the thin film magnetic head, the ceramic bar where the plurality of element portions are formed is polished, and a process for machining a throat height or an MR height of each element part to a suitable level is executed. In general, in the magnetic disc apparatus, in order to stabilize the output characteristics from the magnetic head, it is necessary to keep a distance between the magnetic polar portions of the magnetic head and a surface of a recording medium to an extremely narrow constant distance. The value of the throat height or the like is used as an important parameter for defining this distance.
In the following description, the throat height means a length (height) of the tip end portion of the magnetic poles for performing the recording/reproduction of magnetic signals in such a head core part, i.e., the portion where the two magnetic poles face each other at a fine gap. Also, the MR height means a length (height) from the end portion of the MR element on the side facing the medium to the opposite end portion thereof. In order to make it possible to perform the suitable recording/reproduction of the signals, the values of the throat height, the MR height and the like must be selected suitably. In order to obtain the predetermined values, high precision is needed for the polishing work.
The ceramic bar is to be cut into respective element portions in a process thereafter. Each of the element portions constitutes a part of a magnetic head for the magnetic disc apparatus. In the case where the magnetic head is used in the magnetic disc apparatus, the ceramic portion becomes a slider that is to be lifted away from the magnetic disc by the blow pressure caused by the rotation of the disc. The element portion becomes a head core for performing the recording and/or reproducing the magnetic signals of the disc.
However, in general, the above-described ceramic bar has a strain, a bend or the like due to the stress caused by the formation of the element portion or the cutting operation from the ceramic substrate. It is therefore difficult to obtain the high machining precision only by fixing the ceramic bar and effecting the polishing work thereon. For this reason, a non-general polishing apparatus for performing the polishing work of the magnetic head with high precision in the form of the ceramic bar as disclosed in, for example, U.S. Pat. No. 5,620,356 or the like has been proposed. Also, the present assignee proposes some apparatus and some methods (Japanese Patent Application No. 11-162799 or the like).
An actual polishing method for the above-described ceramic bar will now be described.
First of all, the surface opposite the polishing surface of the ceramic bar, is fixed with adhesives or the like to a jig, and the surface to be polished of the ceramic bar is depressed through the jig against the polishing surface of a polishing base to perform the polishing work to the surface to be polished. The jig has a beam structure. A load is applied to several, three to seven, specific points on the jig from the outside of the jig to thereby cause deformation in the jig as a whole. Furthermore, this beam structure allows the portions fixed to the ceramic bar to be subjected to the complicated deformation by the balance adjustment of the above-described load, and the ceramic bar is bent simultaneously with the fixed portions to thereby make it possible to correct the bend or the like owned by the ceramic bar per se.
In the polishing work, in a predetermined element portion on the ceramic bar fixed to the jig, the values such as a throat height are measured optically or electrically to thereby obtain the difference between the measurement value and the target value, i.e., the amount of polished portion needed upon the measurement. The loads at the plurality of points are adjusted on the basis of the necessary polishing amount in the predetermined element portion obtained and the portion in the vicinity of the predetermined element portion, and the ceramic bar is polished while being deformed through the jig. These steps are repeated whereby the values such as the throat height and the like of all the elements formed in the ceramic bar fall within the predetermined range.
Opening portions into which pins or the like may be inserted are formed in the beam portion of the jig. The loads to the jig in the above-described process are given by transmitting the loads due to an actuator such as a low friction cylinder to the pins inserted into the opening portions of the jig through transmission parts. The adjustment of the loads to the jig is performed by adjusting the loads from this actuator, i.e., a drive amount of the actuator. Incidentally, Japanese Patent Application No. 10-178949 filed by the present applicant discloses a specific example of a jig for causing an effective deformation or a load distribution to the ceramic bar.
In a recording density in the current magnetic disc apparatus or the like, it is possible to make the values such as a throat height fall within an allowable range to some extent by a machining method of the magnetic head using the above-described jig. However, the high recording density is accelerated, and recently, the high precision of the throat height or the miniaturization of the elements are remarkable. It is difficult to make the values such as the throat height fall within the allowable range over the full length of the ceramic bar.
In the case where the allowable range of the values such as the throat height is narrowed, there is an approach to cope with this by, for example, increasing the application points of the loads that cause the deformation in the jig. However, since this leads to the increase of the number of the actuators that actually apply the loads or the transmission portions (application points) of the loads, if the actuators or the like used in the conventional apparatus are needed, it is difficult to actually perform this approach since the space for mounting the actuators or the like would be increased remarkably in view of the structure of the polishing apparatus. Also, in the case where the jig per se is miniaturized in accordance with the miniaturization of the elements, there would be a problem in that it is difficult to arrange the necessary number of the actuators or the like for applying the loads to the application points of necessary loads, and the like.
Furthermore, in the conventional polishing method, since the affect of the repulsive force from the polishing surface exists between the application point of the load and the beam or between the application points, it is impossible to sufficiently deform the ceramic bar. Accordingly, also in some conventional cases, depending upon the allowable range of the values such as a throat height, the values of the portion that may not be deformed could not fall within the allowable range. The approach to increase the number of the application points of the load and the number of the actuators for this problem has been attempted but there is a limit in the allowable range due to the above described problem.
Also, the conventional apparatus has three to seven actuators for deforming the jig in addition to the actuator for applying the main pressure for depressing the ceramic bar against the polishing surface and adjusting the load balance at both end portions in the longitudinal direction of the ceramic bar. However, actually, in order to bend the retainer portions to a necessary level, the three to seven actuators have to have a large stroke due to the necessary bend level and the actuators that always have the large stroke and occupy the large space in the structure are necessary as in the conventional case. Moreover, in order to make it possible to provide the complicated bend, the opening portion of the jig into which the pins cooperating with the actuators are inserted is increased to provide the form that may imparts a moment in the vertical direction, in the lateral direction and in the rotational direction with respect to the opening portion. In addition, it is necessary to effect the complicated drive control for each actuator. Accordingly, the conventional apparatus is not suitable for imparting the predetermined deformation amount to the very restricted portions of the ceramic bar.

Machining apparatus for workpiece and method therefor


Methods and compositions are provided for preventing or inhibiting neuronal degeneration, or for promoting nerve regeneration, in the central nervous system (CNS) or peripheral nervous system (PNS), or for protecting nerves from glutamate toxicity, which comprises administering to an individual in need thereof an effective amount of the copolymer poly-Glu,Tyr.

The nervous system comprises the central (CNS) and the peripheral nervous system (PNS). The CNS is composed of the brain spinal cord and visual system; the PNS consists of all of the other neural elements, namely the nerves and ganglia outside of the brain and spinal cord.
Damage to the nervous system may result from a traumatic injury such as penetrating trauma or blunt trauma, or a disease or disorder including, but not limited to, Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), diabetic neuropathy, senile dementia, stroke and ischemia.
Maintenance of CNS integrity is a complex "balancing act" in which compromises are struck with the immune system. In most tissues, the immune system plays an essential part in protection, repair, and healing. In the CNS, because of its unique immune privilege, immunological reactions are relatively limited. A growing body of evidence indicates that the failure of the mammalian CNS to achieve functional recovery after injury is a reflection of an ineffective dialog between the damaged tissue and the immune system. For example, the restricted communication between the CNS and blood-borne macrophages affects the capacity of axotomized axons to regrow; transplants of activated macrophages can promote CNS regrowth.
Activated T cells have been shown to enter the CNS parenchyma, irrespective of their antigen specificity, but only T cells capable of reacting with a CNS antigen seem to persist there (Hickey et al, 1991). T cells reactive to antigens of CNS white matter, such as myelin basic protein (MBP), can induce the paralytic disease experimental autoimmune encephalomyelitis (EAE) within several days of their inoculation into naive recipient rats (Ben-Nun, 1981). Anti-MBP T cells may also be involved in the human disease multiple sclerosis (Ota et al., 1990). However, despite their pathogenic potential, anti-MBP T cell clones are present in the immune systems of healthy subjects (Pette et al, 1990). Activated T cells, which normally patrol the intact CNS, transiently accumulate at sites of central nervous system white matter lesions (Hirschberg et al, 1998).
A catastrophic consequence of CNS injury is that the primary damage is often compounded by the gradual secondary loss of adjacent neurons that apparently were undamaged, or only marginally damaged, by the initial injury. The primary lesion causes changes in extracellular ion concentrations, elevation of amounts of free radicals, release of neurotransmitters, depletion of growth factors, and local inflammation. These changes trigger a cascade of destructive events in the adjacent neurons that initially escaped the primary injury. This secondary damage is mediated by activation of voltage-dependent or agonist-gated channels, ion leaks, activation of calcium-dependent enzymes such as proteases, lipases and nucleases, mitochondrial dysfunction and energy depletion, culminating in neuronal cell death. The widespread loss of neurons beyond the loss caused directly by the primary injury has been called "secondary degeneration."
One of the most common mediators which cause self-propagation of the diseases even when the primary risk factor is removed or attenuated is glutamate, an excitatory amino acid capable of displaying dual activity: playing a pivotal role in normal CNS functioning as an essential neurotransmitter, but becoming toxic when its physiological levels are exceeded. Elevation of glutamate has been reported in many CNS disorders. In its role as an excitotoxic compound, glutamate is one of the most common mediators of toxicity in acute and chronic (including optic nerve degeneration in glaucoma) degenerative disorders (Pitt et al., 2000). Endogenous glutamate has been attributed to the brain damage occurring acutely after status epilepticus, cerebral ischemia or traumatic brain injury. It may also contribute to chronic neurodegeneration in such disorders as ALS and Huntington's chorea.
Intensive research has been devoted to attenuating the cytotoxic effect of glutamate by the use of locally acting drugs, such as N-methyl-D-aspartate (NMDA)-receptor antagonists. Conventional therapy of this type is often unsatisfactory, however, as in neutralizing the toxic effect it is likely to interfere with the physiological functioning. In humans, such compounds have psychotropic and other side effects that make them unsuitable as therapeutic agents. They also have the disadvantage of interfering with the essential physiological functioning of glutamate as a ubiquitous CNS neurotransmitter. Because glutamate activity is essential for normal physiological functioning, yet is potentially devastating after acute injury or in chronic CNS disorders, any attempt to neutralize its harmful effect must do so without eliminating its essential activity at other sites in the body.
Another tragic consequence of CNS injury is that neurons in the mammalian CNS do not undergo spontaneous regeneration following an injury. Thus, a CNS injury causes permanent impairment of motor and sensory functions.
Spinal cord lesions, regardless of the severity of the injury, initially result in a complete functional paralysis known as spinal shock. Some spontaneous recovery from spinal shock may be observed, starting a few days after the injury and tapering off within three to four weeks. The less severe the insult, the better the functional outcome. The extent of recovery is a function of the amount of initially undamaged tissue minus the loss due to secondary degeneration. Recovery from injury would be improved by neuroprotective treatment that could reduce secondary degeneration. For example, alleviation of the effect of glutamate is a frequent target of neuroprotective drug development. Among the drugs which are being developed for this purpose are N-methyl-D-aspartate (NMDA)-receptor or alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)-receptor antagonists. These drugs will inevitably have severe side effects as they interfere with the functioning of NMDA and AMPA receptors, which are crucial for normal CNS activity. One of the most intensely studied NMDA-receptor antagonist is MK-801 (dizocilpine), which provides effective neuroprotection but with severe side effects. In animal models of cerebral ischemia and traumatic brain injury, NMDA and AMPA receptor antagonists protect against acute brain damage and delayed behavioral deficits. Such compounds are undergoing testing in humans, but therapeutic efficacy has yet to be established. Other clinical conditions that may respond to drugs acting on glutamatergic transmission include epilepsy, amnesia, anxiety, hyperalgesia and psychosis (Meldrum, 2000).
In the laboratory of the present inventors, it has recently been discovered that activated T cells that recognize an antigen of the NS of the patient confer neuroprotection. Reference is made to U.S. application Ser. Nos. 09/218,277 and 09/314,161 and PCT Publication WO 99/60021, the entire contents of which is hereby incorporated herein by reference. More specifically, T cells reactive to MBP were shown to be neuroprotective in rat models of partially crushed optic nerve (see also Moalem et al, 1999) and of spinal cord injury (see also Hauben et al, 2000a). Until recently, it had been thought that immune cells do not participate in NS repair. Furthermore, any immune activity in the context of CNS damage was traditionally considered detrimental for recovery. It was quite surprising to discover that NS-specific activated T cells could be used to protect nervous system tissue from secondary degeneration which may follow damage caused by injury or disease of the CNS or PNS. The mechanism of action of such NS-specific T cells has yet to be discovered, but the massive accumulation of exogenously administered T cells at the site of CNS injury suggests that the presence of T cells at the site of injury plays a prominent role in neuroprotection. It appears, however, that the accumulation, though a necessary condition, is not sufficient for the purpose, as T cells specific to the non-self antigen ovalbumin also accumulate at the site, but have no neuroprotective effect (Hirschberg et al, 1998).
In addition to the NS-specific activated T cells, the above-referenced US applications and PCT publication WO 99/60021 disclose that therapy for amelioration of effects of injury or disease of NS can be carried out also with a natural or synthetic NS-specific antigen antigen such as MAG, S-100, β-amyloid, Thy-1, P0, P2, a neurotransmitter receptor, and preferably human MBP, human proteolipid protein (PLP), and human oligodendrocyte glycoprotein (MOG), or with a peptide derived from an NS-specific antigen such as a peptide comprising amino acids 51-70 of MBP or amino acids 35-55 of MOG.
More recently, it has been discovered in the laboratory of the present inventors that a high molecular weight synthetic basic random copolymer consisting of L-Ala, L-Glu, L-Lys and L-Tyr residues with an average molar fraction of 0.141, 0.427, 0.095 and 0.338, designated Copolymer 1 or Cop 1 and being the active ingredient of COPAXONE® (Teva Pharmaceuticals Ltd., Israel), a medicament for the treatment of multiple sclerosis, is able to prevent or inhibit neuronal degeneration, or to promote nerve regeneration, in the CNS or PNS, as well as to protect CNS cells from glutamate toxicity. Reference is made to copending U.S. application Ser. No. 09/765,301 and No. 09/765,644, and PCT International Publications WO 01/52878 and WO 01/93893, the entire contents of which is hereby incorporated herein by reference. More specifically, Cop 1-specific activated T cells were shown to accumulate in both injured and non-injured neuronal tissues and to be protective in the injured optic nerve against the destructive effect of secondary degeneration, and immunization with Cop 1 was shown to protect against glutamate toxicity.
Oral administration of autoantigen in order to obtain "oral tolerance" has been disclosed for the treatment of various autoimmune diseases. For example, EP 359 783 discloses the oral administration of MBP for the treatment of multiple sclerosis. PCT International Publications WO 91/12816, WO 91/08760 and WO 92/06704 all disclose the treatment of other autoimmune diseases using the oral tolerance method with a variety of autoantigens. Treatment of multiple sclerosis by ingestion or inhalation of Cop 1, to achieve suppression of the autoimmune T cell response to myelin antigens, has been disclosed in WO 98/30227.
The copolymer poly-Glu,Tyr, formerly often termed polyGT and hereinafter called poly-Glu,Tyr, poly-YE or pEY, is a random heterocopolymer of L-glutamic acid and L-tyrosine, with a capacity to elicit strong immune response in certain mouse strains (Vidovic et al., 1985; Vidovic and Matzinger, 1988). More than 20 years ago it was shown that several inbred as well as congenic resistant strains of mice, which fail to respond to pYE, were shown to develop specific plaque-forming cell (PFC) responses when stimulated by YE complexed to an immunogenic carrier such as methylated bovine serum albumin (MBSA), and that pre-immunization with pEY has a tolerogenic effect on the response to YE-MBSA in some mouse strains and this tolerance can be transferred to normal, syngeneic recipients by spleen cells or thymocytes of EY-primed animals (Debre et al., 1975). More recently, the activation of murine Vy5NV61-TCR(+) epidermal T cell lines by Glu-Tyr polypeptides has been studied. The physiologic role of γδ-T-cell-receptor (TCR)-bearing cells and the TCR ligands that they recognize is still poorly understood. One possible antigen for γδ-TCR(+) cells is poly-Glu,Tyr, because poly-Glu,Tyr-reactive γδ-TCR(+) hybridoma cells were produced from poly-Glu,Tyr-immunized mice (Seo et al., 2001).
None of these publications relates to, or suggests, the use of poly-Glu,Tyr for neuroprotection.
Citation or identification of any reference in this section or any other part of this application shall not be construed as an admission that such reference is available as prior art to the invention.

This patent is subject to a terminal disclaimer.

Poly-Glu,Tyr for neuroprotective therapy


A sense of touch electronic tuning device with background noise suppression and tuning note identification features to verify tuning of acoustic and electrically amplified stringed, reed and wind musical instruments, said tuning device comprising a sound sensor, signal conditioning system, power supply, reference tuning note identification system and vibrator to produce vibration felt by the person using said tuning device when the musical instrument to which said tuning device is directly or indirectly connected, produces musical notes, in tune, within an acceptable tolerance range of acoustic pitch.

The present invention relates to an accessory to verify the tuning of musical instruments and pertains particularly to an improved electronic tuner providing sense of touch indication for acoustic or electrically amplified stringed, reed, and wind instruments, the tuner being used by a person, hereinafter referred to as the "player". Musical notes from the instrument, hereinafter referred to as "tuning notes", are "in tune" when within an acceptable tolerance range of acoustic pitch determined by the tuner.
It is frequently necessary to adjust tuning of a musical instrument during use and tuning is typically verified by prior art tuners including oral pitch pipes, percussive tuning forks, or audible or visual electronic tuners. Pitch pipes, tuning forks and audible electronic tuners produce sounds to which the instrument is qualitatively tuned by ear, tuning accuracy depending on the sensitivity of the player's ear to pitch. Although visual electronic tuners provide quantitative indication that the instrument is in tune by a light display or rotating needle, they are not usable by blind musicians. Prior art tuners have the disadvantage that they must be handled during use so that the player's hands are not free to adjust tuning of the instrument and a place is not always available to physically rest the tuner. Some electronic tuners can be attached to the instrument to free the player's hands, but are distracting to view and difficult to position. Another problem with prior art electronic tuners is identification of a reference tuning note when the desired tuning note is substantially out of tune, requiring the use of a manual switch before automatic switching for the remaining tuning notes can take place. This problem occurs because an electronic tuner cannot distinguish between tuning notes of nearly the same pitch, for example D and E which are both a string on the guitar. The problem is further complicated by the inclusion of temporarily unused tuning notes in the tuner's sensing capability, such as D below low E, available for non-standard tuning, or the bass tuning notes of a combination bass-guitar tuner. Pick up of background noise is also an inherent problem with prior art tuners.
In the present invention I disclose an improved electronic tuner which picks up minimal background noise and provides rapid and accurate indication that selected tuning notes are in tune by quiet vibration, conveniently felt by both blind and sighted players. Three alternate component arrangements improve upon the convenience of tuner location, including; placement of all tuner components on the musical instrument; placement of the vibrator on the person of the player, connected by radio transmission, to the sensor attached to the instrument; or placement of the tuner on the person of the player with sealed contact between the instrument and the sound sensor attached to the tuner. These tuner placement options free the player's hands to rapidly adjust tuning without distraction and it is not required to find a place to rest the tuner. Improved tuning note identification with the tuner of the present invention eliminates the need for manual switching. One tuning sequence option is to first distinguish a reference tuning note by intermittent vibrator operation and then identify the remaining tuning notes by steady vibrator operation. Another tuning sequence is to distinguish the reference tuning note by vibrator operation at a frequency which is substantially different than the frequency used to identify the remaining tuning notes. Many other tuning note identification sequences are possible using variations of these basic sequences. Tuning note identification by sense of touch is preferred to audible or visual methods because quiet and fully automatic rapid tuning can be performed while the player's hands are free of distracting switch operation. Pick up of background noise is reduced with the tuner of the present invention because the sensor is either in contact with or inside of the instrument.


An autonomously navigating solar swimming pool skimmer employing a forward impeller, navigation being improved by the use of forward mounted powered horizontal bumper wheels as deflectors, combined with occasional reversals of paddlewheels and bumper wheels to clear clogs and navigate away from obstacles. Further improvements include corrosion inhibiting enclosures for motor and electronics, disposable filter media, pool intrusion alarm, an alarm to warn of debris clogs and stuck positions, floatation trim adjustments, debris backwash prevention, electronic control circuitry, intermittent operation during the night, and thrust enhancing features.

1. Field of Invention
This invention relates to autonomously operating solar powered swimming pool skimmers, specifically to those with mechanisms diverting them from collisions with swimming pool walls.
2. Background of the Invention
Most dirt entering a swimming pool first rests on the water surface as floating debris for a period of hours before sinking. Hand held skimmer nets are labor intensive, and debris typically sinks before a skimming opportunity arises. In the process of using hand held skimmer nets, debris is inadvertently caused to sink to the bottom. Skimmers associated with the main pool filtration system typically operate on timers that also typically miss skimming opportunities. They additionally require immense amounts of electricity relative to the skimming effort being performed, and are frequently precluded from being used by automatic bottom scrubbing devices that are powered by the same main pool filtration system.
Bow mounted paddle wheel style impellers have long been recognized as the most energy efficient dirt, debris, and oil skimming device in harbor skimmers, and have more recently been proposed for use on autonomous self propelled swimming pool skimmers powered by solar cell arrays. This style impeller does not require high skimmer velocity, which is difficult to obtain under limited solar power.
Such solar pool skimmers have the advantages of low power usage, availability when most needed, no cords or hoses, and the ability to propel themselves about the pool. Several such devices have been proposed. Their design is constrained by extremely low energy levels available, the need to prevent backwash of debris back into the pool when turned off, dealing with debris clogged impellers or water entrances, and the difficulty of navigating out of tight corners and away from obstructions, such as ladders and pool toys. Several notable solar skimming devices have been proposed:
U.S. Pat. No. 5,106,492 to Distinti et al. uses a bow paddle wheel effectively for propulsion and skimming, and one embodiment uses a floating weir to limit debris backwash when the unit is off. Such floating weirs function well on high power harbor skimmers, but presents considerable resistance to flow in low power solar skimmers. It has a single un-powered bow deflector wheel on a flexible boom. This deflects the skimmer away from certain wall collisions, but allows it to become stuck in sharp corners, from which there are no means to escape. It includes an interesting warning alarm for a full filter, but that alarm relies on measuring the weight of essentially weightless floating debris.
U.S. Pat. No. 4,900,432 to Arnold et al. uses bow a paddlewheel to throw debris over a barrier to prevent backflow, and uses a secondary sideways thrusting impeller to steer away from a wall. The fixed barrier above water level works well for large harbor skimmers, but creates too great of a workload for a small solar device and severely inhibits propulsion. It also suffers from large debris becoming stranded on top the fixed barrier in normal operations, with no means available for its automatic removal. The side thruster steer away from many stuck positions, but doesn't extract the skimmer from acutely angled corners.
U.S. Pat. No. 5,128,031 to Midkiff uses a pump downstream of a filter rather than the conventional bow paddle wheel, diverting the thrust of the outlet of the pump in a random fashion. Then he employs a solenoid valve to divert the thrust through backwards nozzles in response to bow impacts. This involves forward ram style of debris collection requiring a speed that is beyond the power capacity of reasonable size solar cell arrays. Ram style of filtration requires quite high forwards velocity, difficult to achieve in a solar powered device, and a positive mechanism to inhibit backwash of debris when turned off. Midkiff did not propose any sort of backwash preventing means on the rather wide mouthed water entrance of his invention.
U.S. Pat. No. 6,074,553 to Haski similarly employs a ram filter, and an underwater impeller, utilizing forward protruding rods to act on rear rudders or thrust nozzles, thereby causing collisions to divert the thrust to one side or the other. His device lacks any backwash prevention or mechanism to allow his skimmer to extract itself from acute angled corners. Like other similar devices, it will work well for a time, but requires human intervention frequently when it finally becomes stuck.
Therefore swimming pool skimming devices heretofore known suffer from a number of disadvantages:
a) Manual skimmer nets, while cheap and effective, are labor intensive and typically miss catching debris before it sinks.
b) Many skimmers commonly in use rely on the main swimming pool filters, typically requiring hundreds or thousands of times as much electric power as do autonomous solar powered skimmers. As a result, they are typically not run frequently enough to catch debris before it sinks.c) Other skimmers require cords and hoses stretched across the pool, creating a hazard for swimmers.d) Proposed solar skimmers lack autonomous ability to extract themselves from the worst stuck positions.e) Proposed solar skimmers lack effective and foolproof means of preventing backwashing of debris out of the filter when stopped.f) Most proposed solar skimmers require more power for skimming and propulsion than is available from reasonable size solar cell arrays.g) Proposed solar skimmers loose essentially all propulsive effect when used with filters fine enough to filter the finest of dust floating on a pool surface. This fine dust represents a sizeable fraction of the total filtration load.h) All other skimmers lack provisions for dealing with the severe corrosion problems of motors in swimming pool environments.

Autonomously navigating solar swimming pool skimmer