A bandgap voltage reference circuit having temperature curvature correction, comprises a bandgap voltage source configured to generate an output voltage, and a novel curvature correction circuit. The correction circuit is responsive to the bandgap voltage source output voltage and connected to apply a curvature correction signal to the bandgap voltage source to compensate for output voltage temperature dependency of the bandgap voltage source.

Bandgap references are high-performance analog circuits that are applied to analog, digital and mixed-signal integrated systems. For such applications, the accuracy of the bandgap reference voltage is a significant component of system functionality, important particularly in such precision applications as converters. Bandgap references use the bandgap voltage of underlying semiconductor material (often crystalline silicon) to generate an internal DC reference voltage that is based on the bandgap voltage.
Many bandgap references forward bias the base-emitter region of a bipolar transistor to form a voltage VBE across its base-emitter region. VBE is then used to generate the internal DC reference voltage. VBE, however, exhibits some first-order, second-order and higher order temperature dependencies. Many bandgap references substantially eliminate the first-order temperature dependency by adding a Proportional-To-Absolute-Temperature (PTAT) voltage to VBE.
One such bandgap voltage reference circuit is disclosed in U.S. Pat. No. 3,887,863 to A. P. Brokaw. The bandgap voltage reference circuit disclosed in the '863 patent relies upon a bandgap cell that is commonly referred to as a "Brokaw cell." Referring to FIG. 1 of the drawings herein, Brokaw cell 100 comprises a pair of bipolar transistors (Q1 and Q2) and a pair of resistors (R1 and R2). The area of the base-emitter regions in Q1 and Q2 are indicated by A and unity, respectively, wherein A is greater than unity.
A bandgap voltage reference circuit 200 incorporating a Brokaw cell 100 is shown in FIG. 2. In addition to the Brokaw cell 100, the bandgap voltage reference circuit 200 comprises an operational transresistance amplifier R, as well as a pair of resistors R3 and R4 that allow the reference output voltage (VOUT) to exceed the bandgap voltage.
During operation, a voltage of VBE develops across the base-emitter region of bipolar transistor Q2. In addition, a PTAT voltage (termed VPTAT) develops across resistor R2. The base-emitter voltage (VBE) of a bipolar junction transistor has a negative temperature coefficient generally between −1.7 mV/degree C. and −2 mV/degree C. In contrast, the PTAT voltage has a positive temperature coefficient. By matching the temperature coefficient of VBE of Q2 to the temperature coefficient of VPTAT) of R2, the first order temperature coefficient of VBE can be made to be nearly zero, thereby significantly reducing temperature dependency.
Although the described bandgap voltage reference circuit substantially eliminates first-order temperature dependencies in the output voltage, second and higher order temperature dependencies tend to persist. A plot of output voltage as a function of temperature yields an approximately parabolic curve that reaches a maximum at about the ambient temperature of the bandgap reference.
Some bandgap references have reduced second and higher order temperature variations in the output voltage. One such bandgap voltage reference circuit is disclosed in U.S. Pat. No. 5,767,664 to B. L. Price. FIG. 3 of the drawings herein illustrates such a bandgap reference 300, which is shown to include the conventional bandgap reference 200 of FIG. 2, as well as a V-to-I converter circuit 304 with two differential pair segments 306 which are made up of MOSFETs M1-M4. A current mirror 308 is formed with MOSFETs M5 and M6 so as to extract a correction current, ICORR, from the VB node. The correction current reduces a significant portion of the remaining temperature dependencies present in the bandgap reference 200. Accordingly, the voltage at node VB is relatively temperature stable, and as a consequence, the output voltage of the bandgap reference 300 is a DC voltage that similarly is relatively stable with temperature changes compared to uncompensated bandgap reference 200.
Although effective for the purpose intended, the '664 bandgap reference curvature correction circuit has disadvantages. For example, in the '664 circuit, the correction current supplied to the reference requires some bandgap multiple as an output, that is, the bandgap requires gain. In addition, as the correction current is developed across a feedback resistor, that resistor must match the bandgap core resistors. The feedback resistor also will have to match the output voltage divider string to precisely set the gain. Thus, all the resistors need critical matching to each other. Furthermore, the '664 circuit implements a current mirror circuit to source compensation current, that will tend to impose magnitude and drift error. The inventive subject matter described herein addresses these and other concerns.

Bandgap curvature correction and post-package trim implemented therewith


A biodegradable resin composition that exhibits excellent antistatic properties and antifogging properties while maintaining its molecular weight to such a degree as to provide practically satisfactory strength of a molded article molded even according to a kneading process.

Plastics such as polypropylenes, polyethylenes and poly(vinyl chloride)s derived from fossil resources such as petroleum, are molded typically into food packaging films, electric appliances and industrial materials and are very important materials essential for our livelihood. It is, however, well known that these plastics are not biodegradable, thereby remain in the nature semipermanently after their use, significantly affect an ecosystem, and lead to destruction of environment in various ways.
Under these circumstances, biodegradable resins have received attention. Among them, biodegradable resins prepared from plants (vegetables), namely, plant-derived biodegradable resins are to be used as replacements from fossil resource-derived non-biodegradable plastics. In particular, poly(lactic acid) resins have recently received attention and have been produced increasingly. They have received attention for the following reasons. Social demands have been made on providing cycling systems of matter in which limited fossil resources are saved and thoroughly reused as resources. Under these circumstances, plastics derived from fossil resources are considered to be remarkably out of the cycling systems of matter. In contrast, poly(lactic acid)s are expected to constitute cycling systems of matter, in which the poly(lactic acid)s are recycled as resources, because they are prepared from saccharides derived from plants such as corn and potatoes, or lactic acid as fermented products of such saccharides.
Materials for poly(lactic acid) resins are synthetically prepared from saccharides derived from grains which are recycling capable resources such as corn and potatoes, or lactic acid as fermented products of such saccharides. In addition, poly(lactic acid) resins which become unnecessary are easily hydrolyzed in natural environments and decomposed by the action of microorganisms and ultimately become water and carbon dioxide gas.
Films, sheets, and other molded resinous articles including biodegradable resins such as poly(lactic acid) resins are known to exhibit performance equivalent to that of conventional plastics. Among them, poly(lactic acid) resins have very high transparency and are very usable in packaging uses in which transparency is an important factor. In addition, they have water vapor permeability equal to or better than that of conventional oriented polypropylene (OPP) or oriented polystyrene (OPS) films and are expected to replace these films.
As is described above, biodegradable resins have many advantages and are applicable to molded articles such as films and sheets. However, since they have electrical insulating properties typical to resins, they are very susceptible to being electrically charged as in regular resins, and thereby they have various problems due to electrical charges. Such problems include, for example, crawling of ink upon printing, flying out of contents to be packaged upon packaging, and dust adhesion to products to impair appearance of the products.
Biodegradable resins also have problems caused by low hydrophilicity typical to plastics. For example, films for food packaging should have transparency so as to see the appearance of food packaged therein, but the surfaces of such films become fogged due to water drops derived from water vapor from the food.
To solve these problems, a kneading process of previously adding a surfactant to a resin has been employed. According to the kneading process, the surfactant bleeds out from the inside to the surface of the resulting molded article to form a surfactant layer, and thereby exhibits performance such as antistatic properties and antifogging properties. These properties may sustain to some extent even when the surfactant at surface is wiped off, because the surfactant in the inside of the resin bleeds out again to thereby recover the properties. As is described above, the performance is exhibited as a result of bleedout of the surfactant from the resin according to the kneading process. However, the degree of bleedout is believed to vary significantly depending on the crystallinity of the resin, such as degree of crystallization and degree of orientation of crystals, and the compatibility (miscibility) between the resin and the surfactant. Among such factors, the crystallinity of the resin and the compatibility of the surfactant also significantly affect the appearance of the resin.
Patent Document 1 demonstrates that a polyhydric alcohol and a fatty acid ester thereof are incorporated into a poly(lactic acid) resin to provide antistatic films and sheets. Patent Document 2 describes that antistatic properties are imparted to a poly(lactic acid) by containing a nonionic surfactant including a glycerol fatty acid ester. Patent Document 3 shows that antistatic properties are imparted to a caprolactone resin as a biodegradable resin by containing a nonionic surfactant including a glycerol fatty acid ester. Patent Document 4 demonstrates that antistatic properties are exhibited while suppressing deterioration in transparency due to an alkylsulfonate salt by containing an alkylsulfonate salt of a nonionic surfactant in combination with a polyhydric alcohol or a fatty acid alkylolamide compound. The resulting resins prepared according to these techniques, however, do not have practically sufficient antistatic properties yet. Such surfactants having poor compatibility with resins also markedly affect the appearance of the resins and, in particular, significantly impair the transparency of poly(lactic acid)s that are featured by transparency.                Patent Document 1: Japanese Patent Application Laid-open No. Hei 9-221587 (pages 1 to 9)        Patent Document 2: Japanese Patent Application Laid-open No. Hei 10-36650 (pages 1 to 14)        Patent Document 3: Japanese Patent Application Laid-open No. 2002-60603 (pages 1 to 5)        Patent Document 4: Japanese Patent Application Laid-open No. 2003-261757(pages 1 to 6)        Patent Document 5: Japanese Patent Application Laid-open No. Hei 9-278936(pages 1 to 14)


An ergonomic bicycle pedal with removable platform comprises a pedal axle configured to receive a pedal body A socket extends integrally from the underside of the removable platform. A front hook and a rear hook extend integrally from the underside of the platform with the front hook configured and sized to engage a front channel and a rear hook configured and sized to engage a rear channel. Both the front and the rear channels are configured to allow rotational movement along two axes by having the socket moving on top of the ball and having the front hook moving within the front channel and the rear hook moving within the rear channel.

1. Field of the Invention
The invention relates generally to a pedaling system for bicycles but more particularly to a system having a removable platform that can be fitted on a shoe.
2. Background of the Invention
It is well known in competitive cycling to have part of the pedal attached to the footwear of the cyclist and having a specially configured footwear clip to the rest of the pedaling system of a bicycle.
The drawback of such an approach has to do with safety. Indeed, the foot is either tied to the pedal, as found in earlier system and in which case it can be the cause of serious injury when a cyclist falls, or the foot is clipped onto the pedal, which allows for the release of the foot in case of a fall, but that approach is not foolproof. Moreover, the clip does not allow for much in the freedom of movement of the foot and can create alignment problems with various parts of the leg which can cause strain injuries over time.
Moreover, these approaches require a special shoe configured to be attached to the pedal which makes these shoes very uncomfortable especially when cyclist disembarks from his bicycle and wants to walk about.
Clearly, there is a need for a safer and more comfortable type of bicycle pedaling system.

Ergonomic bicycle pedal with removable platform


A device of a supplementary navigation satellite is provided. The device includes a unit for generating navigation signals, the signal strength of the navigation signals being dimensioned in such a way that it is still possible to receive signals of other satellite navigation systems.

The invention relates to a regional navigation satellite supplementary system.
A navigation system must not only allow positioning of the user with the required precision, continuity, and availability, but also provide the other information necessary for navigation. This other information is typically provided on paper via a map, on a storage media, via traffic radio messages, which are also distributed in digital form.
The street grid maps used in the navigation systems are usually fixed and typically require user interaction to obtain regular updates. Using known techniques, information about current or future traffic obstructions is available only on the local or regional level (if at all), and interregional information (which is also significant for planning longer trips) is typically not easily available. Accordingly, conventional systems do not necessarily provide selective detour recommendation that account for new traffic obstructions that could arise due to bypass recommendations.
Exemplary embodiments of the present invention provide devices and methods which allow traffic obstructions to be bypassed. This allows the street infrastructure to be used significantly more effectively because traffic obstructions may be bypassed. Moreover, the present invention significantly reduces the effort that a user must expend to have current planning documents for his trips.
In accordance with exemplary embodiments of the present invention, the navigation satellites of the navigation satellite supplementary system which are located over an area in which a service is to be provided are located close to the zenith and transmit a relatively strong navigation signal into the service area. For example, these satellites may fly on suitable geosynchronous orbits, on geosynchronous orbits in or near the equatorial level, or also on so-called Molniya orbits.
These satellites are then implemented as controllable using a (vertically) oriented antenna, to achieve the highest possible signal strength in the service area with the least possible power consumption, the signal strength being dimensioned in such a way that the signals of other satellite navigation systems may still be received. This is achieved, inter alia, by a suitable selection of the coding of the signals.
The signals transmit navigation-relevant information at a data rate which is significantly above the data rate of the commercial service of Galileo. This information contains, inter alia, current and expected traffic obstructions in the service area, recommendations for how specific user groups having various travel directions and travel destinations (which may be regionally combined) are to drive around these traffic obstructions, changes of the street grid in the service area, and also comprise expected traffic obstructions due to environmental influences, chronologically recent changes being repeated relatively frequently and chronologically earlier changes being repeated relatively rarely (which may be no repetition at all). The invention also discloses arbitrary combinations of the above-mentioned navigation-relevant information.
Exemplary embodiments of the present invention include a method for transmitting a navigation signal that involves generating navigation signals, wherein the signal strength of the navigation signals is dimensioned in such a way that it is still possible to receive signals of other satellite navigation systems, and wherein the signals transmit navigation-relevant information at a data rate which is significantly above the data rate of the Galileo satellite system; and transmitting the generated navigation signals.
The features specified in connection with the embodiments of the device of the invention are also disclosed for the method.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

Regional navigation satellite supplementary system


A method and heating system for a hose and dispenser wand of a hot melt mix applicator using a three phase heating element powered by a generator to heat the hose and wand to maintain hot melt mix material within the hose and wand in a flowable state. To selectively energize the generator to control heat input, the heating system has (1) a controller in communication with a temperature sensor carried by the hose or wand, and (2) an output in communication with a generator control input. The generator control input enables operation of the generator to be controlled by the controller for controlling heating of the hose and wand. The heating element is a cord having a first wire receiving a phase of the three phase current, a second wire receiving another phase of the current, and a third wire receiving another phase of the current, with the cord being wrapped about the hose and wand in a helical configuration. The generator preferably is a vehicle alternator modified so that it outputs three phase electrical power without requiring any voltage or current regulation. In a preferred method, the controller energizes the generator when the sensed temperature of the hot melt mix falls to or below a predetermined setpoint control temperature and deenergizes the generator when the sensed temperature rises to or above a predetermined setpoint control temperature.

Hot melt mix applicators are used to apply hot melt mix, in the form of an asphalt or bituminous hot melt material, on areas such as paved roads and the like for sealing, patching, or repairing the roads. These types of applicators are also used to apply hot melt material to hold in place raised or recessed pavement markers and to seal and protect inductive traffic loops.
In one such commercially successful hot melt mix applicator heretofore marketed by the assignee herein and disclosed in U.S. Pat. No. 4,692,028, the applicator has a tank for heating and storing hot melt mix that is pumped by a pump through a hose and a wand onto pavement. During periods of operation where an operator wishes not to apply mix, but desires the mix to remain hot enough to be applied on demand, the wand is inserted into a holster connected to the tank. With the wand in the holster, the pump continuously circulates mix through the hose, wand, holster and back into the tank so that it will not harden in the wand or hose and obstruct flow.
When use of the applicator is finished, the pump is briefly reversed to clear the hose and wand of hot melt mix material before the hot melt mix is allowed to cool. Unfortunately, should hot melt mix harden within either the hose or the wand, it can partially obstruct or completely block flow through the hose causing an operator to have to clean out the hose and wand before the applicator can be used to apply hot melt mix.
To improve upon this method of preventing obstruction of the hose and wand, a single phase electrical heating system has been used to prevent hot mix material from solidifying in the hose and wand. In operation, a temperature sensor on the wand or hose communicates temperature to a controller which regulates the heat input of a heating element of the system that is in contact with the hose and wand by regulating electric power applied to the element.
In the construction of the heating element, a single heating element wire and a non-heating neutral wire makeup a two-wire heating element cord that is wrapped around the hose and wand in a spiral or helical fashion. Unfortunately, a rather dangerous electric potential of at least about 110 volts A.C. is applied to the heating element during operation to heat the hose and wand. As a result, the risk of shock is great should wires become exposed or otherwise become insufficiently insulated during operation.
Additionally, because only one wire of the pair of wires of the heating element cord wrapped around the hose can generate and transmit heat, the cord must be relatively tightly coiled around the hose and wand with a minimum of space between coils to provide the proper heat flux to prevent the hot melt mix from solidifying. Unfortunately, since only one wire of the two wire heating element cord can generate heat and since both wires of the cord bear against the hose and wand, the amount of heating element wire per unit length of cord is not maximized leading to less efficient heating element operation.
Moreover, for particularly long lengths of hose, such as hoses that are about twelve feet in length or longer, more than one temperature sensor must be used in a single phase heating system to provide adequate temperature regulation so that the hose and wand will be properly heated during operation. This additional sensor disadvantageously increases the cost and potential maintenance of the heating system while it also increases the complexity and difficulty of properly heating both the wand and hose to maintain them at a temperature which will ensure good hot melt mix flow through the hose and wand.
In the control of the heating element, the temperature controller simply regulates current flow from a single phase alternator to the heating element by turning current flow on and off. In determining whether current flow should be supplied, the controller has a selectively adjustable thermostat which communicates with the temperature sensor. If the sensed temperature is too high, the thermostat will cause the controller to turn off current flow to the heating element. If the sensed temperature is too low, the thermostat will cause the controller to turn on current flow to the heating element.
To control single phase current flow, the controller is wired in series with the heating element and simply functions as an on/off switch in response to input from a temperature sensor in communication with the hose or wand. The controller does not control operation of the alternator nor the engine. It simply functions as a switch to turn on and off current flow to the heating element.
The alternator is a conventional alternator that is connected by pulleys and a belt to a drive shaft of an internal combustion engine for supplying electrical power. The alternator has an integral power regulation circuitry to convert its raw three phase lower voltage output into single phase A.C. current having a regulated voltages of at least about 110 volts. Unfortunately, this power regulation circuitry adds to the cost of the system without adding any advantage in its use or operation.
What is needed is a more efficient and economical wand and hose heating system that more safely operates at lower voltages while still providing adequate heat to maintain hot melt mix within the hose and wand at a flowable state. What is also needed is a hot melt mix applicator of relatively compact and mobile construction that has a heated hose and wand for maximizing convenience and performance of the applicator.

Hot melt mix applicator with electrically heated hose


A method and apparatus for treating garments, particularly to impart a "stone-washed" look without using pumice stones, using an elongated drum having an inclined axis and two continuous helical flights placed within the drum. Garments subjected to treatment in the drum with liquids and chemicals normally used in stone-washing operations, but without pumice stones, will have an appearance and feel like that of a normally-formed stone-washed garment. The helical flights may also have projection fins to help the abrading operation. The method is much more economical in terms of both supplies, equipment, and labor than the conventional stone-wash technique.

Some of the most popular garments today have a stone-washed appearance. Stone-washing is intended to give a garment at the time of purchase the look and feel normally achieved through repeated washings. Stone-washing, which involves tumbling wet garments with pumice stones to give the desired appearance and feel, has drawbacks including:
1. Pumice stones impart abrasion and impact upon the garments being treated. A heavier thread, therefore, is required, increasing the garment unit cost, while at the same time reducing the stitch rate in the sewing process and substantially reducing productivity.
2. Damage is caused to the seams and hems of stone-washed garments even though heavier thread is used; 15% or more of stone-washed garments have to be reworked at substantial cost. A significant number of the reworked garments are damaged to the extent that they must be downgraded in value and sold as seconds (irregulars).
3. Pumice stones are expensive; they break down and have to be replaced after only a few uses. The sand resulting from the breakdown of the pumice stones constitutes a substantial clean-up and disposal problem.
4. Pumice stones by their nature are highly abrasive, causing excessive equipment wear. Existing process drums are often replaced on an annual or biennial basis.
5. Stone-washing is extremely labor intensive as each garment has to be manually handled to remove pumice stone and sand from all pockets, sleeves, pant legs, etc.


A method of determining electrochemical charge acceptance limits by measuring and determining the peak of the curve of Differential Equivalent Series Resistance (DESR) of a cell or system for the purpose of monitoring or controlling processes internal to the cell/system (i.e.; state-of-charge or state-of-formation) or for monitoring or controlling processes external to the cell/system (i.e.; battery chargers or battery formers). The method is suitably embodied in software, firmware, hardware, or apparatus.

The present invention relates generally to charging and discharging electrochemical systems and more particularly to improved methods and apparatus for monitoring, manufacturing, charging, and discharging electrochemical cells and systems commonly referred to as batteries.
Although rechargeable batteries are available in many different styles and having many different chemistries, they all share a common dependence upon optimal charging for optimal performance. The consequences of non-optimal charging are largely two-fold.
The first consequence is the most obvious in that failure to provide a full charge to a battery will result in less than the maximum potential energy available to operate the system to which the battery is attached. This results in more frequent charging and less operating time between charges for the powered system. A second consequence is not as obvious, but may become far more important to sophisticated users. This consequence is the loss of battery life which translates directly into cost-of-ownership of the battery. Depending upon the chemistry or construction of a battery, undercharging or overcharging a battery has different but detrimental effects on the usable life of the battery.
The bulk of battery chargers on the market are either constant current chargers that charge to a specified voltage end point, or constant voltage chargers. Some are two stage chargers that charge at a constant current to some voltage and then switch to constant voltage. Constant current chargers are fast but tend to undercharge batteries. Constant voltage chargers are slow. Both types and their hybrid suffer from the fact that their end voltage is set by design and, therefore, is almost never optimum. Some chargers have added sensors to compensate for the temperature coefficient of battery terminal voltage which addresses only one variable. Some newer chargers have implemented dV/dt detection as a method of terminating charging, which still requires the choice of a dV/dt limit, which is also sensitive to various parameters.
Pressure monitoring has also been proposed as a specific solution for lead acid batteries. Some recent chargers use the exothermic or endothermic behavior of some chemistries at full charge as a method to stop charging. Taylor (U.S. Pat. No. 3,816,807) proposes a method of imposing an AC voltage on top of a DC charging current and monitoring the behavior of the complex impedance that results from the AC voltage with a phase detector. He describes a relationship between the real (in phase) impedance and the imaginary (out of phase) impedance that can be used to maintain the output of a charger close to the acceptance limit of a battery. Cherng (U.S. Pat. No. 5,469,043) proposes a method of sweeping a charging voltage from low to high and using information contained in a dV/dI curve to determine the optimum charging voltage. Both of these methods are complex and expensive to implement.

Method of monitoring and controlling electrochemical systems and processes


A display panel includes a light blocking pattern and a polarizer. The light blocking pattern is disposed on a base substrate. A plurality of opening areas is defined based on the light blocking pattern. The polarizer includes a plurality of linear patterns spaced apart from each other. The plurality of opening areas includes a color area transmitting color light and a white area transmitting white light. The polarizer overlaps the color area and the white area.

Field
Exemplary embodiments relate to a polarizer, a display substrate and a display panel including the polarizer, and more particularly to a polarizer used to a display apparatus, a display substrate including the polarizer, a display panel including the polarizer and a method of manufacturing the polarizer.
Discussion of the Background
A liquid crystal display apparatus applies voltage to a liquid crystal layer to change arrangement of the liquid crystal layer. Accordingly, optical phenomenon such as birefringence, optical rotation, dichroism, light scattering or the like cause an optical change in the liquid crystal layer, thereby resulting in the display of an image on the display apparatus.
Generally, the liquid crystal display apparatus includes a display panel, a backlight assembly and a receiving container. The display panel includes a first substrate and a second substrate, and the backlight assembly includes a light source. Thus, the display panel displays an image by transmitting the light from the light source.
Recently, a transparent display apparatus using external light, such as natural light or fluorescent light, without the light source has been developed. The transparent display apparatus includes a polarizer to control light transmittance. The polarizer may transmit a polarization component parallel to a transmitting axis, and may block a polarization component perpendicular to the transmitting axis. The polarizer may absorb some of light, and thus, light efficiency of the liquid crystal display apparatus may undesirably decrease.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

Polarizer, display substrate, display panel having the same and method of manufacturing the same


A method and apparatus for detecting and determining the location of a coverage hole in a communications network such as a cellular communication system wherein the location is determined from operational parameters and/or by network elements themselves. Additionally is a method to reduce a hole by adjusting antennae parameters preferably remotely and automatically and this can be done in conjunction with hole location to optimize the system.

Cellular communication networks typically comprise a network of base stations, each covering a certain geographic area (cell). Communication occurs usually between base stations and user equipment under the general control of a network controller and network managed from element management system (EMS) or network managements system (NMS). In this way, planners can locate base stations so as to operate in a way that provides coverage for particular populations within the context of a wider geographical area.
The invention has particular, but not exclusive application to self-organising networks (SON) using 3GPP (3rd Generation Partnership Project) and NGMN (Next Generation Mobile Networks). Coverage hole detection recovery is a use case in 3GPP and NGMN. Use case is about automatic detection of coverage holes in the network and automatic fixing of the hole.
The optimum coverage areas of cells may change for various reasons. On-going urbanisation, for example, may lead to holes developing in a cellular network. Other factors which lead to necessary changes that have to be made in order to optimise a cellular system include addition of new base stations, or when a base station malfunction occurs or if planning was suboptimum. Below optimal coverage leads to waste of network resources and lower quality of service (QoS).
In order to detect such holes in a cellular network, the prior art approach was to perform an expensive standardised drive test to detect possible coverage holes.
It is to be noted that in general the term "hole" is to be construed in general terms; at one extreme may be considered as a total loss of communication connectivity at a particular location. However it may be considered as a reduction in the quality of connectivity at a particular location within a network.
Active Antenna Systems (AAS) is a technology which provides improved system performance and radio network capacity as well as being a candidate to decrease radio site installation and operating costs. AAS systems had been technically challenging to implement, but recently most of the technical obstacles have been overcome. Adaptive antennas provides beam-forming capability using various parameters such as number of active antennas on horizontal or vertical plane, amplitude and phase of an antenna element, and average power so that antenna beam are able to be rotated, tilted, and formed electrically.
A sub-form of AAS is a so-called remote antenna tilt (RET), in which only antenna down-tilt is altered electrically. The methods described in the present invention can be applied to RET as well.
An aim of the embodiments is to provide a method of detecting the existence and location of holes in a communication network. A further aim is to provide a method of fixing or improving such a coverage hole. Yet a further aim is to optimise the performance of a communication network.

This patent is subject to a terminal disclaimer.

Method of improving coverage and optimisation in communication networks


Polyamines containing primary amino groups are made by hydrolyzing an isocyanate with water in the presence of a solvent which is a carboxylic acid amide. The solvent must be used in a quantity of at least 10% by weight solvent based on 100% by weight of isocyanate. The weight ratio of solvent to water must be from 3 to 200. A homogeneous phase is maintained during the hydrolysis which is carried out at temperatures of from 20.degree. to 210.degree. C. A not incorporable basic and/or metal catalyst particularly alkali metal hydroxides may be employed. The polyamines produced by this process are particularly useful for the production of polyurethanes.

This invention relates to a simplified one-step process for the preparation of polyamines containing primary amino groups.
It is known that aromatic isocyanates can be converted into primary aromatic amines by acid hydrolysis.
However, the amine resulting from this hydrolysis reacts with as yet unreacted isocyanate to form the corresponding urea thereby decreasing the amount of product amine. This secondary reaction cannot be suppressed even by using an excess of strong mineral acids. A recent example of this procedure is described in JP-P 55 007 829.
It is also known that isocyanates can be converted into amines by an acid or alkaline catalyzed reaction, as disclosed, for example, in N. V. Sidgwick, The Organic Chemistry of Nitrogen, Clarendon Press, Oxford, page 236 (1966) and in J. March, Advanced Organic Chemistry; Reactions, Mechanisms and Structure, McGraw-Hill Book Co., New York, page 658 (1968). Sidgwick indicates that isocyanate groups can be hydrolyzed under alkaline conditions but no details of such a process are disclosed. J. March also speaks in general terms of the fact that the hydrolysis of isocyanates and isothiocyanates to amines can be catalyzed with acids and bases. The occurrence of isocyanates as intermediate products is also known to those skilled in the art. For example, isocyanates are obtained in the course of the Curtius or Lossen degradation of acid azides and hydroxamic acids and are decomposed with aqueous acids to form amine salts. A procedure of this kind has been described, for example, in Organic Synthesis, Coll. Vol. IV, 819 (1963) in which the preparation of putrescine, hydrochloride is used as an example.
E. Mohr, J. prakt. Chem., 71 133 (1905) was one of the first to observe that phenyl isocyanate is more rapidly attached by dilute sodium hydroxide solution than by water at low temperatures. C. Naegeli et al., Helv. Chim. Acta, 21, 1100 (1938) report that when phenyl isocyanates substituted with electron acceptors (such as nitro groups, halogen atoms or acyl groups) are hydrolyzed in moist ether or in acetone containing 1% of water in the absence of acids or bases, the corresponding monoamines are obtained in the course of a reaction lasting from several minutes to up to one hour. From 2,4-dinitrophenyl isocyanate the amine can even be obtained in hot water without solvent in a virtually 100% yield and without side reactions leading to urea formation.
In a process for preparation of specified primary aromatic amines containing polyalkylene glycol ether segments described in DE-B 1,270,046, products obtained by the reaction of aromatic di- or triisocyanates with polyalkylene glycol ethers and/or polyalkylene glycol thioethers (preferably those with molecular weights of from 400 to 4000) are reacted with secondary or tertiary carbinols and then subjected (optionally in the presence of acid catalysts) to thermal decomposition at high temperatures in an inert solvent. One disadvantage of this process, apart from the high decomposition temperature, is that combustible, readily volatile alkenes which are explosive when mixed with air are formed in the course of thermal decomposition so that appropriate safety measures are required.
DE-B 1,694,152 (believed to correspond to U.S. Pat. No. 3,525,871) relates to the preparations of prepolymers containing at least two amino end groups by the reaction of hydrazine, aminophenylethylamine or other diamines with an isocyanate prepolymer obtained from a polyether polyol and polyisocyanate (NCO/NH ratio=1:1.5 to 1:5). Any unreacted amine must be carefully removed in a subsequent step of the process because the amine is a powerful catalyst in the reaction with polyisocyanates and shortens processing times, and may even act as a reaction component. A similar process is described in U.S. Pat. No. 3,931,116.
Another method for synthesizing polyamines containing urethane groups is described in FR-P 1,415,317 (believed to correspond to U.S. Pat. No. 3,385,829). In this process, isocyanate prepolymers containing urethane groups are reacted with formic acid to yield N-formyl derivatives which are saponified to aromatic amines having amino end groups. The reaction of isocyanate prepolymers with sulphamic acid according to DE-P 1,115,907 also leads to compounds containing amino end groups. Relatively high molecular weight prepolymers containing aliphatic secondary and primary amino groups may be obtained according to De-B 1,215,373 by the reaction of relatively high molecular weight hydroxyl compounds with ammonia in the presence of catalysts under pressure at elevated temperatures. According to U.S. Pat. No. 3,044,989 high molecular weight amines may be obtained by the reaction of relatively high molecular weight polyhydroxyl compounds with acylonitrile followed by catalytic hydrogenation. Relatively high molecular weight compounds containing amino end groups and urethane end groups may also be obtained according to DE-A 2,546,536 (believed to correspond to U.S. Pat. No. 4,224,417) and U.S. Pat. No. 3,865,791 by the reaction of isocyanate prepolymers with enamines, aldimines or ketimines containing hydroxyl groups, followed by hydrolysis. Another method for the synthesis of aromatic polyamines containing urethane and ether groups is opening of the ring which occurs in the reaction of isatoic acid anhydride with diols. Polyamines of this kind have been described, for example, in U.S. Pat. No. 4,180,644 and DE-A 2,019,432, (believed to correspond to U.S. Pat. No. 3,808,250) 2,619,840, (believed to correspond to U.S. Pat. Nos. 4,169,206 and 4,260,557), 2,648,774 (believed to correspond to U.S. Pat. Nos. 4,129,741 and 4,247,677), and 2,648,825 (believed to correspond to U.S. Pat. No. 4,153,801). Aromatic ester amines obtained by such methods have the disadvantage of being insufficiently reactive for many purposes.
Low reactivity is also found in compounds containing amino and ester groups obtained according to U.S. Pat. No. 4,504,648 by the reaction of polyether polyols with p-aminobenzoic acid ethyl ester and according to EP 32,547 (believed to correspond to U.S. Pat. No. 4,328,322) by the reaction of polyols with nitrobenzoic acid chloride followed by reaction of the nitro groups to amino groups.
The reaction of nitroaryl isocyanates with polyols followed by reduction of the nitro group to aromatic amine groups is also known (U.S. Pat. No. 2,888,439). The main disadvantage of this process is the high cost of the reduction stage of the process.
It is also known that certain heteroaromatic isocyanic acid esters can be converted into heteroaromatic amines by basic hydrolysis. The conditions for hydrolysis disclosed by H. John in J. Prakt, Chemie 130, 314 et seq and 3323 et seq (1931) for two quite specific heteroaromatic monoisocyanic acid esters are, however, both completely unsuitable for the conversion of polyisocyanate compounds into aliphatic and/or aromatic amines and dangerous.
Applicants' own processes disclosed in DE-A 2,948,419 and 3,039,600 (believed to correspond to U.S. Pat. No. 4,386,218) are multistage processes for the preparation of polyamines by alkaline hydrolysis of isocyanate prepolymers using an excess of base (alkali metal hydroxides) at low temperatures to form carbamates, acidification with equivalent or excess quantities of mineral acids or acid ion exchanger resins accompanied by carbamate decomposition, and optionally neutralization of excess quantities of acid by means of bases, followed by isolation of the polyamines.
DE-OS 3,131,252 (believed to correspond to U.S. Pat. No. 4,540,720) discloses a process in which the carbamates obtained in a first stage by hydrolysis with alkali metal hydroxides are decomposed by subsequent heat treatment to yield the polyamines.
One-step processes for the production of polyamines are described in DE-OS 3,223,400 (EP-97,299), (believed to correspond to U.S. Pat. No. 4,970,342) DE-OS 3,233,398 (EP-97,298; believed to correspond to U.S. Pat. No. 4,565,645) and DE-OS 3,233,397 (EP-97,290) (believed to correspond to U.S. Pat. No. 4,515,923). In these one-step hydrolysis processes various solvent-catalyst combinations are employed. "Ether solvents" are used together with tertiary amines as catalysts in DE-OS 3,223,400 (believed to correspond to U.S. Pat. No. 4,970,342). Polar solvents such as dimethylformamide are used together with tertiary amines or relatively large quantities of alkali metal hydroxides, alkali metal silicates or alkali metal cyanides as catalysts in specified amounts in DE-OS 3,233,398 (believed to correspond to U.S. Pat. No. 4,515,923). Carbonates or carboxylates are used in specified amounts in polar solvents such as DMF in DE-OS 3,233,397 (believed to correspond to U.S. Pat. No. 4,565,645.
All of these processes for the preparation of polyamines are elaborate and expensive. Even in the last mentioned, more simplified methods for the conversion of polyisocyanates to polyamines, further simplification would be desirable for obtaining polyamines even more economically with even better conversion rates of NCO/NH.sub.2 (i.e. higher NH.sub.2 numbers) by an even smoother reaction. A satisfactory process should have the following advantages compared with conventional processes:
(1) no filtration required; PA1 (2) no separation of a tertiary amine catalyst by distillation required; PA1 (3) drastic reduction in the quantity of catalyst (both tertiary amines (according to DE-OS 3,223,398) and the inorganic, alkaline compounds such as KOH) required so that the catalyst could be left in the polyamine; and PA1 (4) quantitative conversion of NCO into NH.sub.2 groups (high NCO/NH conversion rates, i.e. high amine numbers close to the theoretical value); PA1 (5) no removal of by-products required; and PA1 (6) simple working up of polyamines and auxiliary substances.


Effective control of the common-mode level of amplifiers is obtained through control structures (both closed-loop and open-loop structures) which are directed to various amplifier functions such as the reduction of amplifier loading, accurate sensing of common-mode levels, mitigation of headroom restraints, and proper transistor biasing. This common-mode control is especially useful in multiplying analog-to-digital converters (MDACs) of signal processing systems.

1. Field of the Invention
The present invention relates generally to the control of amplifier common-mode levels.
2. Description of the Related Art
Differential amplifiers are used in a variety of signal conditioning systems (e.g., pipelined signal converters) to generate residue signals for conversion in successive converter stages to thereby provide digital codes that correspond to analog input signals. The accuracy of the residue signals and, hence, that of the signal conversion, is directly related to the performance of differential amplifiers which generally operate in first and second operational modes. It has been found, for example, that poorly controlled common-mode levels can substantially degrade the accuracy of residue signals.

Amplifier networks with controlled common-mode level and converter systems for use therewith


A mechanism for measuring the variability of the read current of SRAM cells on an integrated circuit includes the integrated circuit having an SRAM array including a plurality of SRAM cells. The integrated circuit may also include a selection circuit configured to select a particular SRAM cell in response to a selection input. An oscillator circuit such as a ring oscillator, for example, on the integrated circuit may be configured to oscillate at a frequency that is dependent upon a read current of a selected SRAM cell during operation in a first mode. A frequency determining circuit that is coupled to the oscillator circuit may be configured to output a value corresponding to the frequency of oscillation of the oscillator circuit.

1. Field of the Invention
This invention relates to the field of integrated circuits and, more particularly, to test circuits and memory devices.
2. Description of the Related Art
Circuits such as static ram (SRAM) cells are widely used as computer memory to store bits of information. SRAM is used particularly in applications where access speed is required because SRAM cells provide relatively fast access times compared to their dynamic RAM counterparts. However, SRAM devices may be more expensive to manufacture. Thus, SRAM arrays are typically used in processor cache memory, while DRAM devices are typically used as computer system main memory due to such factors as cost. One issue with manufacturing the SRAM cells is depending on process parameters during manufacturing, it may be possible for the read current associated with each SRAM cell to vary from cell to cell and between manufacturing lots. This variability may present reliability problems, particularly when attempting to design associated sense amplifiers for the SRAM cells.
The manufacturing of integrated circuits is a complex process. Bringing a new circuit design to a fabrication facility, or bringing an existing circuit design to a new fabrication facility may require a number of characterization steps to establish a device library. Depending on the process technology, and the complexity of the circuits, there may be several iterations of process adjustments to ensure reliable operation of the manufactured devices. In many cases, there may be several revisions of silicon before the design is fully operational. Accordingly, it may be desirable to provide a robust circuit design while reducing the number of iterations of process adjustments, particularly during device and process characterization.

Mechanism for measuring read current variability of SRAM cells


A narrow band-pass interferometric filter for applying a response characteristic to an input signal to produce a filtered output signal. The filter is comprised of an inverting amplifier having an amplifying input to which the input signal is applied, an inverting input and an output. Coupled between the output and the inverting input of the inverting amplifier is an interferometric processing circuit which produces a signal having a generally constant positive amplitude except for a null at a pass frequency of the response characteristic for the filter. As the inversion of the signal produced by the signal processing circuit is the response characteristic of the filter and the amplitude thereof is greater than the amplitude of the input signal, the inverting amplifier passes the input signal whenever the frequency of the input signal matches the pass frequency of the filter. If, however, the frequency of the input signal is other than the pass frequency of the filter, the amplitude of the signal applied to the inverting input is greater than the amplitude of the input signal. Accordingly, the output of the inverting amplifier is driven to an inversion of the signal applied to the inverting input, The signal processing circuit may include a phase shift circuit which shifts the input signal by 180 degrees or a time delay circuit which delays the input signal by a time period generally equal to the period required for the input therealong.

In its broadest sense, a filter encompasses any electrical network capable of selecting signals within a specified frequency range. One type of filter is commonly known as a "band-pass" filter. For such a filter, signals within a specified frequency band pass through the filter unattenuated while signals outside the specified frequency band are greatly attenuated. Like other types of filters, a band-pass filter may be configured to include only passive components such as resistors, capacitors and inductors or may alternately be configured to include active components such as transistors and integrated circuits. A specific class of filters, commonly referred to as "high Q-factor" or "high Q" filters, are particularly favored for narrow band-pass applications. The Q of a filter is the ratio of the reactance to the resistance of the electrical network which forms the filter and "high Q" filters refer to those filters in which the aforementioned ratio is on the order of about 1,000. High Q filters typically provide a response characteristic having very narrow pass bands, i.e., a response characteristic having on the order of about a 3 dB drop for a 5% shift off its resonant pass frequency.
A commonly recognized drawback to existing filter designs is the existence of a time delay between application of a signal to an input side of a filter in a rest state and entry of the filter into an active state whereby the filter's response characteristic is applied to the input signal. While the aforementioned time delay, which will hereafter be referred to as the "response delay" of a filter, will vary depending on the particular design of the filter, a typical response delay for a filter may range between 100 .mu.sec and 2 msec. As a result, therefore, filters often fail to detect input signals of relatively short duration, commonly known as "bursts", particularly when the duration of the burst is less than the response time of the filter. While response delays occur in all conventional filter designs, they are of particular concern for high Q, narrow band-pass filters which typically include more and/or larger components which require longer charging times. Thus, it has been generally recognized that, as the band-pass for a filter is narrowed and its Q is increased, the response delay for that filter increases. Thus, the design of a filter capable of passing an increasingly narrow frequency band while maintaining an acceptable response delay characteristic has remained problematic.
Turning to FIG. 1a, a response characteristic 10 for a conventional narrow band-pass filter (not shown) may now be seen. As may now be seen, the narrow band-pass filter is tuned to frequency f.sub.C. As the input signal sweeps through a range of frequencies, the amplitude of the response characteristic will start at zero, gradually increase, peak at center frequency f.sub.C and then gradually decrease back to zero. FIG. 1b illustrates the response delay which occurs in the narrow band-pass filter having the response characteristic illustrated in FIG. 1a in response to the application of a signal having frequency f.sub.C to an input side thereof. At time t.sub.0, both the input signal 12 applied to the narrow band-pass filter and the output signal 14 produced by the response characteristic of the narrow band-pass filter are at zero. At time t.sub.2, a burst which lasts until time t.sub.4, is applied to the input side of the narrow band-pass filter. If the narrow band-pass filter had an ideal, i.e., 0 sec., response delay, the output signal 14 resulting from applying the response characteristic 10 to the input signal 12, would also appear at time t.sub.1. However, the narrow band-pass filter will remain inactive for a latency period 16 which extends from the application of the input signal at time t.sub.1 to time t.sub.3. During the latency period 16, the narrow band-pass filter is storing current in a start-up resonant mode. From time t.sub.1 to time t.sub.2, no output signal passes through the narrow band-pass filter. As the burst continues past time t.sub.2, energy begins to build in the form of a resonance. Accordingly, an output signal begins to build at the output of the narrow band-pass filter. When the level of the output signal reaches the average signal level of the input signal at time t.sub.3, the latency period 16 ends and a stimulation period 18 begins.
A similar delay in the response of the narrow band-pass filter occurs upon removal of the input signal. 12. At time t.sub.4, the input signal 12 applied to the input side of the narrow band-pass filter is removed. Upon removal of the input signal 12, the output signal 14 will continue at full strength for a short time period, i.e., until time t.sub.5, and then begin to taper off to until returning to zero at time t.sub.6.
It should be readily understood that there would be innumerable advantages for implementing a "real-time" narrow band-pass filter, i.e., a narrow band-pass filter having a response characteristic enhanced by the reduction or elimination of the response delay. Such a filter would have innumerable applications in industry. For example, as a filter having little or no response delay would be able to extract a desired signal from a relatively short signal burst, resolution of the desired signal on a cycle-by-cycle basis becomes possible. Currently, however, no real-time implementation of a narrow band-pass filter characterized by little or no response delay are known. It is noted that several non-real-time solutions to the problems caused by the response delay of filters have been proposed. Such solutions generally involve sampling the input signal and performing a mathematical analysis of the data in the frequency domain. While such techniques can resolve very short signal bursts occurring at a specific frequency, the computational time required can be rather significant. Thus, non-real-time solutions are not particularly suited for most filter applications.
What is needed, therefore, is a band-pass filter having a narrow pass response characteristic similar to existing high Q band-pass filters but avoids the response delay of such filters.

Narrow band-pass interferometric filter having enhanced operational characteristics


A transmission mechanism and a pressure oil supply system therefor are provided for use in work vehicles provided with a work device externally of the body of the vehicle at longitudinal one side thereof, the transmission mechanism being simple in construction and serving to shorten the overall length of the vehicle while holding a transmission shaft interconnecting a PTO shaft and an input shaft for the work device close to a horizontal.

1. Field of the Invention
The present invention relates to transmission mechanisms for vehicles having an HST (hydrostatic transmission), and more particularly to a transmission mechanism for work vehicles equipped with a work device externally of the vehicle body, and also to a pressure oil supply system for the mechanism.
2. Description of the Related Technology
It is commonly demanded that various vehicles be shortened in forward or rearward length to diminish the turning radius, improve the ease of driving and achieve cost reductions. Especially, this is strongly demanded of work vehicles which are equipped with a work device externally of the vehicle body in front or in the rear thereof.
Work vehicles provided with a work device externally of the vehicle body have a PTO shaft at a portion of the transmission for transmitting power to the work device. With such work vehicles, it is desired that the transmission shaft interconnecting the PTO shaft and the input shaft of the work device be disposed horizontally to the greatest possible extent in order to prevent the joints of the transmission shaft from giving off noise and assure the joints of improved durability. For example, JP-U1 No. 56555/1993 and JP-A No. 204135/1990 disclose transmissions for work vehicles intended to meet this demand. The disclosed arrangements include pulleys or like cooperative means for positioning a PTO shaft 1103 at a lower level than a front axle 1105 to cause the shaft to project from the front end face of the front axle case (as indicated at X in FIG. 19). Generally, the transmission shaft 1104 for a work device 1106 needs to be lengthened (as indicated at Y in FIG. 19) if it is attempted to position the transmission shaft 1104 closer to a horizontal while causing the PTO shaft 1103, as positioned approximately at the same level as the engine drive shaft 1101a, to project from the front end of the front axle case, consequently increasing the overall vehicle length. Alternatively, the transmission shaft 1104 must be inclined (as indicated at Z in FIG. 19) if an attempt is made to shorten the overall vehicle length while causing the PTO shaft 1103 to project from the front end of the front axle case at substantially the same level as the engine drive shaft 1101a, consequently increasing the load on the transmission shaft and impairing the durability of the transmission shaft. In view of these structural drawbacks, the transmissions disclosed in the foregoing publications are so constructed as stated above.
In the case of the conventional construction described, however, a differential gear unit is to be interposed between the engine output shaft (or HST motor shaft) and the PTO shaft, so that the cooperative mechanism between the two shafts must be adapted to avoid the interference with the differential gear unit. This results in an increase in the vehicle cost and an impaired maintenance work efficiency.
With vehicles, especially with work vehicles, it is known to dividedly derive a rear wheel driving force from the output of an HST for driving the front wheels. JP-A No. 66749/1997, for example, discloses such a transmission mechanism. With reference to FIG. 20 showing such a conventional transmission mechanism as is disclosed in this publication, a vehicle comprising a differential gear unit 1140, HST 1120 and drive source 1110 which are arranged from the front of the vehicle rearward has a transmission 1130, in which a driving force from the drive source is divided into a front wheel driving force and a rear wheel driving force. This construction has the following drawbacks. Incidentally, indicated at 1131 in the drawing is a front wheel drive shaft which is coupled to the differential gear unit 1140 for driving front axles 1151, and at 1132 is a rear wheel drive shaft which is connected to a rear axle 1152 by an unillustrated transmission shaft.
The transmission mechanism shown in FIG. 20 essentially requires the transmission 1130, which increases the number of parts and the cost. The provision of the transmission 1130 further entails the problem of impairing the reliability of the vehicle. Since the transmission 1130 serves as a power transmission path for both the front wheel driving force and the rear wheel driving force, the components of the transmission are burdened with a great load. Accordingly, the gears and other components are susceptible to damage, which lowers the reliability of the vehicle. Furthermore, the transmission 1130 is provided in a limited space between the differential gear unit 1140 and the HST 1130, necessitating difficult installation work, which leads to the problem that the vehicle is inefficient to assemble in its entirety.
With work vehicles equipped with a work device externally of the vehicle body, there is a need to provide a considerable distance between the engine and the HST because it is necessary to interconnect the drive source and the HST by means of universal joints. Stated more specifically, the drive source is installed on the vehicle body with rubber vibration isolators interposed therebetween, while the HST is connected to the differential gear casing which is fixed to the front axle cases. A vibration difference therefore occurs between the drive source and the HST. Accordingly, to interconnect the two components by a shaft with the vibration difference absorbed, universal joints are used for the shaft to be connected between the drive source and the HST. For this reason, there is a need to provide a distance permitting the arrangement of two universal joints in series between the HST and the drive source.
With vehicles wherein a PTO unit is provided which has a PTO shaft for a mower or like work device, and a hydraulic clutch for effecting or interrupting the transmission of the output of the PTO shaft, it is desired to position the PTO shaft inwardly of the vehicle body to the greatest possible extent while shortening the distance between the hydraulic clutch and a charge pump for supplying a hydraulic fluid to the clutch.
A shorter distance between the pump and the clutch is desirable because of the difficulty to be encountered in hydraulically controlling the clutch if the distance is great. Inward positioning of the PTO shaft is desirable in order to reduce the overall length of the vehicle including the mower or the like while horizontally positioning the connecting rod between the shaft and the mower or the like.
This will be described with reference to a front mount mower tractor which is equipped with a mower in front of the vehicle body. If it is attempted to shorten the overall length of the vehicle including the mower in an arrangement wherein the PTO shaft is caused to project forward from the front axle case, the transmission shaft interconnecting the PTO shaft and the mower must be given a great inclination. The transmission shaft is pivotally moved vertically when the mower is raised or lowered. If the inclination of the transmission shaft is greater, the angle through which the shaft is pivotally moved also increases, permitting the transmission shaft joints to produce a louder noise and impairing the durability of the joints. It is therefore desired that the PTO shaft be disposed inward longitudinally of the vehicle body (toward the rear of the vehicle body in the case of the front mount mower tractor) in order to shorten the overall length of the vehicle while obviating these drawbacks.
Thus, it is desired that the vehicle wherein the power of the drive source is transmitted to the travel device and to the PTO unit via the HST fulfill the foregoing requirements, whereas transmission mechanisms still remain to be developed which meet all of these requirements.
Conventionally, the following construction has been adopted for the pressure oil supply system for supplying a hydraulic fluid to power steering hydraulic devices or to hydraulic devices for lifting work devices such as mowers. The conventional pressure oil supply system has an arrangement wherein a hydraulic pump for supplying the pressure oil is attached to the drive source of the vehicle, and the casing of the differential gear unit is used also as an oil tank serving as the oil supply source for the hydraulic pump. The pump shaft of the hydraulic pump can be coupled to the drive source easily, while the use of the casing eliminates the cost increase and the increase of the vehicle size that would result if an oil tank for specific use is provided.
However, this arrangement requires an elongated inflow line interconnecting the hydraulic pump and the casing, consequently offering the piping increased resistance which is liable to impair the operation efficiency of the pump. Although the inflow line can be given an increased diameter to reduce the piping resistance, this will entail an increased cost.
The drive source is installed in the vehicle body with use of rubber vibration isolators, while the casing is fixed to the axle case, so that a vibration difference occurs between the hydraulic pump attached to the drive source and the casing. This results in the necessity of using a flexible tube or like pipe which is capable of absorbing the vibration difference between the pump and the casing for the inflow line for holding these two components in communication, hence a higher cost.
In order to shorten the distance between the hydraulic pump and the oil tank, it is possible to install a specific tank in the vehicle, as positioned in a vacant space in the vicinity of the drive source, but the installation of the specific tank leads to a higher cost and a greater vehicle size. Use of such a tank still involves the problem of vibration difference between the oil tank and the hydraulic pump.

Transmission mechanism for vehicles having HST and pressure oil supply system therefor

Abstract: A work vehicle provided with a work device in front of the vehicle body comprises a transmission 30 disposed between a differential gear unit 10 and an HST 20 and providing a travel cooperative mechanism, a PTO shaft projecting from the housing of the HST 20, and a PTO cooperative mechanism disposed in the housing for dividedly deriving power for the PTO shaft from the travel cooperative mechanism for the transmission of the power. The HST 20 comprises a hydraulic pump 22 having a pump shaft 22a for receiving an input at its rear end, and a hydraulic motor 23 having a motor shaft 23a for delivering a front wheel driving force and a rear wheel driving force from the front end and rear end thereof, respectively.


A sprayer assembly includes a frame that supports a tank for storing a liquid chemical. A pump moves the liquid chemical from the tank to one or more spray nozzles through a flexible hose supported by a boom arm that is attached to and extends from the frame. To allow for adjustment of the positioning of the spray nozzles, the boom arm has a curved end portion that defines a slot. A fastener can be passed through the slot and into a corresponding opening defined in the frame to attach the boom arm to the frame. As such, the boom arm can be fixed at any orientation between 90° (vertical position) and 0° (horizontal position) depending on the application.

The present invention relates to a sprayer assembly for the application of fertilizers, weed killers, insecticides, and/or other liquid chemicals to lawns and gardens.
In maintaining lawns and gardens, various types of liquid chemicals are commonly used, including fertilizers, weed killers, and insecticides. These liquid chemicals are often applied using a sprayer assembly of some sort. For example, the sprayer assembly may be comprised of a tank that is towed behind or carried on a tractor, powered lawn mower or all-terrain vehicle (ATV), along with one or more flexible hoses that deliver the liquid chemical to spray nozzles. Furthermore, the sprayer assembly may include a pump or similar means for moving the liquid through the flexible hoses from the tank to the spray nozzles.
In any event, the positioning of the spray nozzles is important to ensure appropriate application of the liquid chemical, and specifically, to ensure that there is appropriate coverage over the desired area. Accordingly, there is a need for a sprayer assembly in which the positioning of the spray nozzles can be readily adjusted.

Sprayer assembly with adjustable boom arms


An automatic trip gate for installation in a gate support structure at a bank of an impounded body of water. The automatic trip gate controls a release of an overflow of water through the gate support structure upon the occurrence of an overflow event. The automatic trip gate includes a plate supported by a hinge assembly that attaches to the support structure. A trough attached to the plate catches and retains overflow water. When the level of overflow water in the trough reaches a tipping level, the plate pivots from a substantially vertical orientation wherein the impounded body of water is maintained behind the plate, to a tipped position wherein the impounded body of water is released o through the gate support. A plunge pool is located below the automatic trip gate that absorbs the energy imparted by the plate when tripped.

A device for diverting flow from a canal drop, small earthen dam or branch to an emergency spillway should a primary diversion fail unexpectedly was required at a small hydroelectric project being developed by the inventors. Several commercial products were available, such as the Obermeir Hydro, Inc. Pneumatically Operated Spillway Gate. This gate consists of a hinged plate held in place by an air bladder. In order to operate, this product includes a control valve, which could fail to operate. In the interest of providing a gate with no controls, a simple, economical alternative was required.


A sheet pressing apparatus assembled to a file processing equipment which has an input tray for stacking sheets and a pickup roller for feeding sheets. The sheet pressing apparatus includes a sheet pressing assembly movably mounted to the file processing equipment, a driving device including a connecting member and a stepping motor, a sensor unit and a control system. The sheet pressing assembly is driven by the stepping motor to be descending through the connecting member. When the sheet pressing assembly descends, the sensor unit touches the sheets and sends a signal to the control system, the control system figures out the thickness of the sheets by calculating steps the stepping motor having passed, then the control system makes the stepping motor further move with certain steps to drive the sheet pressing assembly further descend to apply a suitable pressure on the sheets.

1. Field of the Invention
The present invention relates to a sheet pressing apparatus, and more particularly to a sheet pressing apparatus capable of adjusting the pressure applied on the sheets.
2. The Related Art
Referring to FIGS. 8-9, a conventional sheet pressing apparatus 100′ is assembled to a file processing equipment (not shown). The file processing equipment has a main shell (not shown), a stepping motor (not shown) driving the sheet pressing apparatus 100′, an input tray 300′ for stacking the sheets 200′, a pickup roller 400′. The sheet pressing apparatus 100′ has a sheet pressing assembly 10′, a plurality of rollers 11′ mounted to the sheet pressing assembly 10′, a connecting element 20′ for connecting the stepping motor, and the sheet pressing assembly 10′. The stepping motor drives connecting element 20′ to generate a torque, the torque is applied on the sheet pressing assembly 10′ to drive the sheet pressing assembly 10′ to descend and apply a pressure on the sheets 200′. However, the pressure applied on the sheets 200′ is not controllable. As the thickness of the sheets 200′ increase, the pressure also increase, which brings difficult to separate the sheets 200′ by the pickup roller 400′.

Sheet pressing apparatus with sensor unit and stepping motor


A MEMS device includes: a first actuator having a first fixed end, including a stacked structure of a first lower electrode, a first piezoelectric film, and a first upper electrode, and being able to be operated by applying voltages to the first lower electrode and the first upper electrode; a second actuator having a second fixed end, being disposed in parallel with the first actuator, including a stacked structure of a second lower electrode, a second piezoelectric film, and a second upper electrode, and being able to be operated by applying voltages to the second lower electrode and the second upper electrode; and an electric circuit element having a first action part connected to the first actuator and a second action part connected to the second actuator.

1. Field of the Invention
The present invention relates to a piezoelectric driven MEMS (Micro-electro-mechanical System) actuator.
2. Related Art
Recently, actuators fabricated by using the MEMS technique are drawing the attention. The actuators are driven by electrostatic force, thermal stress, electromagnetic force, piezoelectric force, and so on, and bent and displaced. An actuator using a piezoelectric thin film to rotate a shaft attached to a free end is known (see, for example, JP-A 2003-181800 (KOKAI)).
Furthermore, MEMS devices such as variable capacitance type capacitors and switches using actuators are being studied. The variable capacitance type capacitors and switches using the MEMS technique has, for example, a configuration in which an actuator supported at its first end by a strut provided on a substrate is provided, a movable electrode serving as an action part is provided at a second end of the actuator, a fixed electrode is provided on the substrate surface so as to be opposed to the second end of the actuator, and the distance between the movable electrode and the fixed electrode is changed by the actuator. In other words, the actuator serves as a movable beam.
Especially in the variable capacitance type capacitor including a piezoelectric driven actuator which uses an inverse piezoelectric effect or an electrostrictive effect as drive force for the movable beam, the spacing between the movable electrode and the fixed electrode can be changed sharply and continuously, and consequently the capacitance change rate can be made large. Furthermore, since air or gas can be used as a dielectric between the movable electrode and the fixed electrode, a very large Q factor is obtained. Thus, the variable capacitance type capacitor has a large number of advantages.
Furthermore, it is also possible to cause the variable capacitance type capacitor structure to function as a switch by bringing the movable electrode into contact with the fixed electrode via an extremely thin dielectric film (capacitive type) or bringing the movable electrode into contact with the fixed electrode directly (contact type). Such a switch fabricated by using the MEMS technique has both low on-resistance and high off-condition isolation characteristics as compared with the semiconductor switch, and it is also drawing keen attention.
However, the piezoelectric driven actuator is supported in the air, and has a long thin beam structure including a piezoelectric film interposed between upper and lower electrodes. Therefore, there is a very serious problem that the beam is warped upward or downward by slight residual stress in the material of the piezoelectric film. As a result, it is very difficult to adjust the capacitance value of the variable capacitance type capacitor obtained before and after applying the voltage in conformity with the design and make the drive voltage of the switch a constant value.
For example, in the action part connected to the piezoelectric driven actuator, a bendable displacement quantity D caused by the inverse piezoelectric effect is represented by the following expression.D˜E·d31·L2/t   (1)Here, E is an electric field applied to the piezoelectric film, d31 is a piezoelectric strain constant, L is the length of the actuator, and t is the thickness.
On the other hand, denoting residual strain by Sr, warp Dw of the piezoelectric driven actuator caused by residual strain which is generated in the piezoelectric film when forming the film is approximated by the following expression.DW˜Sr·L2/t   (2)
As appreciated by comparing the expression (2) with the expression (1), the displacement quantity D and the warp DW have similar relations to the length L and the thickness t of the piezoelectric driven actuator. The displacement quantity D and the warp DW are in proportion to the square of the length L, and are inverse proportion to the thickness t. For example, if the length L of the actuator is increased or the thickness t is decreased in order to widen the drive range of the piezoelectric driven actuator, the quantity of the warp DW also increases accordingly. In making the piezoelectric driven range D greater than the warp DW, therefore, geometric contrivance concerning the actuator brings about little effect. There are no ways other than making the absolute value of the residual strain Sr small as compared with the absolute value of piezoelectric strain (E·d31) caused by the inverse piezoelectric effect.
For obtaining a high quality film as regards lead zirconate titanate (PZT) known as a piezoelectric film having a great inverse piezoelectric effect, it is necessary to form a film at the room temperature and then conduct annealing at approximately 600° C. Since the volume contraction is caused by the annealing, the residual strain of the piezoelectric film formed of PZT increases inevitably. On the other hand, aluminum nitride (AlN) and zinc oxide (ZnO) used as the material of the piezoelectric film, which can be formed near at the room temperature and can be controlled in film forming residual stress comparatively precisely by using the film forming condition, are smaller in inverse piezoelectric effect by at least one digit than PZT.
If a piezoelectric material that is great in inverse piezoelectric effect is used as the piezoelectric film of the piezoelectric driven actuator in order to increase the piezoelectric strain, it becomes difficult to control the residual strain and the warp cannot be controlled, as described above. If a piezoelectric material that is comparatively easy in control of residual strain in the piezoelectric film is used, then the inverse piezoelectric effect is small and the piezoelectric driven range cannot be made sufficiently large as compared with the warp of the actuator.
Industrial application of the piezoelectric driven actuator is obstructed by such problems. Because of a great problem in the structure of the piezoelectric driven actuator, i.e., its structure which is thin in thickness and long, the piezoelectric driven actuator is warped largely by slight residual stress. Therefore, it is difficult to fabricate variable capacitance type capacitors so as to yield a constant capacitance or keep drive voltages of switches constant.


A liquid metering and coating assembly for use in a thermal toner fixation unit of a plain paper copier or printer. The assembly consists of a release oil-supply roll having a compliant and flexible porous permeation control layer and a cleaning blade. The cleaning blade is mounted so as to contact the surface of the permeation control material. The cleaning blade removes excess toner and other incidental debris from the surface of the permeation control layer thereby providing a freshly cleaned surface from which controlled amounts of release oil are uniformly coated onto the surface of an adjacent contacting roll.

In a plain-paper copier (PPC) or printer, toner images applied to the surface of paper or other recording medium are fixated by application of heat and pressure. In certain PPC machines fixation is accomplished by passing the image-bearing recording medium between a hot thermal-fixation roll and a pressure roll. When this type of thermal-fixation device is used the toner material is directly contacted by a roll surface and a portion of the toner adheres to the roll surface. With subsequent rotation of the roll the adhered toner material may be redeposited on the recording medium resulting in undesirable offset images, stains, or smears; or, in severe cases, the recording medium may stick to the adhered toner material on the roll and become wrapped around the roll.
To counter these problems materials having good release properties such as silicone rubber or polytetrafluoroethylene are often used for the roll surfaces. Although improving performance of the thermal fixation devices, use of silicone rubber or polytetrafluoroethylene roll surfaces alone do not eliminate the problems. Another approach used to counter the problems is to include release agents with the toner materials to prevent them from adhering to the roll surface. These oilless toners also improve performance of the thermal-fixation devices but again, particularly in the case of high-speed type copying machines, do not completely eliminate the problems associated with toner pickup and transfer.
Toner pickup by the rolls can be controlled by coating the surface of at least one of the rolls of a thermal fixation device with a liquid release agent, such as a silicone oil. It is important that the release liquid be applied uniformly and in precise quantities to the surface of the roll. It is also important that such be done in a manner to permit extended usage of the machine in order to minimize service costs and keep the cost per copy or printed page at a competitive level.
Means to supply release liquids to the heating and pressure rolls of a thermal fixation unit are known in the art and include wicks, pressure pads, and rolls. Such means usually include at least a thick porous material, such as felts of Nomex.RTM. fibers, glass fibers, carbon fibers, or polytetrafluoroethylene fibers, which may be covered with a porous permeation control material, such as porous polytetrafluoroethylene tubing or film. The thick porous material serves as a wick or reservoir for supplying the release liquid, usually a silicone oil, to the surface of a heating-, pressure-, or oil- transfer-roll. Also known in the art as means to supply controlled amounts of release liquids are oil-supply rolls having porous support cores of synthetic polymers, or elastomeric polymers, on the surface of which are porous permeation control layers formed of polytetrafluoroethylene film, or polytetrafluoroethylene film which has been impregnated with a mixture of silicone oil and silicone rubber followed by a heat treatment to crosslink the silicone rubber. Such rolls having highly compliant flexible surfaces are described in U.S. Pat. Nos. 5,123,151 (to Uehara, et al.), 5,232,499 (to Kato, et al.), and European Patent Application Publication No. 0 616 271 A2 (to Kikukawa, et al.).
Initially, thermal fixation units which incorporate such liquid supply devices perform satisfactorily and produce excellent high quality images. However, over a period of time, toner particles and agglomerates, paper particles, and other types of incidental dust and debris deposit on the heating and pressure rolls. The deposited debris can adversely affect the operation of a thermal fixation unit in a number of ways. Particles can damage the surface of the rolls by scratching, denting, or becoming embedded, and thus adversely influence image quality and fixation. Ultimately, they may also be transferred from the heating rolls, pressure rolls, or oil-transfer rolls to the surfaces of the release liquid supply devices, where they adversely influence uniformity and quantity of the oil supply, and where they may further damage the surface of contacting rolls.
To prevent, or at least minimize, damage from such particulate debris, cleaning mechanisms such as scraper blades, wiper blades, or separate cleaning rolls and brushes have been used. For the most part, these mechanisms have been applied so that the scraper blades, wiper blades, etc. are in direct contact with the surfaces of the heating rolls, pressure rolls, or oil-transfer rolls from which they are to remove excess toner, paper particles, and other debris. Damage to the roll surfaces by the scrapers and wipers can occur, as well as damage by particles trapped between the blades and the surfaces. Although such mechanisms significantly improve the length of service-free operation of thermal fixation units, none have prevented the eventual accumulation of particulate debris on the surfaces from which release oil is initially supplied and, consequently, the adverse effect on the uniformity and amount of oil supply which ensues from such accumulation.


A high performance, multiple rotor riding trowel for finishing concrete and hydraulic controls therefor, enabling complete hand control to the operator of steering, propulsion, and blade pitch. A rigid trowel frame mounts two or more downwardly-projecting, bladed rotor assemblies that frictionally engage the concrete surface. The rotor assemblies are tilted with double acting hydraulic cylinders to effectuate steering and control. Double acting hydraulic cylinders also control blade pitch. A joystick system enables the operator to hand control the trowel with minimal physical exertion. The joystick system activates solenoid control valves that in turn energize the various hydraulic cylinders that tilt the rotors and alter blade pitch. The rotor gearboxes are mounted to tiltable, pivot steering boxes secured to the frame within suitable mounting regions bounded by rigid frame elements. The rotor assembly blades contact plastic concrete to finish the surface while supporting the trowel.

1. Field of the Invention
This invention relates generally to motorized riding trowels for finishing concrete surfaces, and to steering and blade pitch control systems therefor. More particularly, the present invention relates to control systems for self-propelled riding trowels, and to trowels equipped with such systems. Representative prior art self-propelled riding trowels are classified in United States Patent Class 404, Subclass 112.
2. Description of the Prior Art
Self-propelled, motorized riding trowels have become widely accepted in the concrete finishing arts. High-power, multiple engine riding trowels are particularly effective. They can finish large surface areas of wet concrete much more efficiently than single engine riding trowels or the older "walk behind" trowels. Significant savings are experienced by the contractor using such equipment, as time constraints and labor expenses are reduced.
Typical motorized riding trowels employ multiple, downwardly projecting rotors. The rotors contact the concrete surface for finishing concrete and support the weight of the trowel. Typically each rotor comprises a plurality of radially spaced apart finishing blades that revolve in frictional contact with the concrete surface. The blades may be coupled to circular finishing pans for treating green concrete. The rotors and their revolving blades are responsible for steering and propulsion. To effectuate steering the rotors are tilted to generate differential forces.
Generally speaking, the more powerful the trowel, the faster finishing operations can be completed. However, the more powerful the trowel, the more difficult it can become to steer the machine. Crisp, responsive handling is important to optimize the efficiency of the troweling process, and to preserve operator safety and comfort.
Holz, in U.S. Pat. No. 3,936,212 describes a three-rotor trowel powered by a single engine. Devices of this nature are difficult to steer, in part because the manually-operated steering linkages that are conventionally employed are inefficient and cumbersome. Further, the drive motor linkages are unreliable and inordinately complex. In U.S. Pat. No. 4,046,484 Holz discloses a twin rotor trowel that is the forefather of many twin rotor designs presently on the market. Trowel steering and propulsion is effectuated by the combination of rotor tilting and blade twisting. Both prior art Holz devices are powered by a single motor. The rotors are driven by an engine mounted on the frame. By tilting the axis of rotation of the rotors, steering and directional control are varied. Frictional forces developed as the blades (or pans) revolve upon the concrete surface resolve into propulsion forces that move the trowel.
Notwithstanding their advantages over older manual systems, early riding trowels based upon the original Holz design were cumbersome and difficult to control. For steering the rotors were tilted with manually operated lever arrangements that projected upwardly from the machine frame. The operator was required to manually control the levers, and a vigorous physical effort was required. The steering characteristics of the trowel disclosed in U.S. Pat. No. 5,108,220, which is owned by the same assignee as in this case, are enhanced. The latter reference discloses a fast steering, high power, twin rotor riding trowel that substantially enhances maneuverability and control over prior twin-rotor machines. Physical labor of the driver is reduced, as the improved linkages and offset couplings therein reduced the effort required to tilt the rotors. However, the driver is nevertheless required to manually deflect levers to steer and control the device.
Significant riding-trowel power is required if large areas of concrete are to be trowelled in a short period of time. U.S. Pat. No. 5,480,258, which is owned by the same assignee as in this case, discloses a multiple engine riding trowel. The twin rotor design depicted therein associates a separate engine with each rotor. As the engines are disposed directly over each revolving rotor assembly, horsepower is more efficiently transferred to the revolving blades. Besides resulting in a faster and more efficient trowel, the design is easier to steer. Again, manually activated steering linkages are used.
Twin-rotor trowels can have "overlap" problems. When the rotors are spaced apart from one another for clearance purposes, an unfinished region between the revolving blades results. To remedy the overlap problem, earlier twin rotor riding trowels meshed their rotor blades to avoid these unfinished intermediate areas. Such designs require synchronization of the propeller-like rotor blades to avoid destructive interference. This timing problem complicates transmission design, especially in single engine riding trowels. In multiple engine designs meshed rotors necessitate properly synchronized motors.
Prior approaches at motor synchronization have been difficult electronically and dangerous mechanically. Another consideration mitigating against the use of meshed rotor trowels is that such designs cannot easily handle finishing pans. Such pans are used to treat green or wet concrete during early stages of the finishing process. They are attached to rotors by seating the rotor blades within suitable brackets. However, they generally cannot be used on trowels where rotor spacing meshes the blades, as adjacent pans collide. To fit pans the rotor spacing must be increased. However, in twin rotor machines if the rotor spacing is increased to accommodate pans, the gap between adjacent rotor blades increases.
Systems that have more than two rotors easily "cover" the intermediate surface area between adjacent rotors, thus avoiding the overlap problem. Coverage results whether the trowel is running blades or finishing pans. Significantly, there is no rotor synchronization requirement in a three or four rotor trowel, as the blades need not be meshed to avoid the overlap problem. However, as rotors are added, drive horsepower must be increased. Steering linkage complexity is aggravated as multiple rotors are added. Further, where separate engines are used with each rotor assembly, more and more physical effort is required to manually tilt the rotors for steering, or to vary blade pitch.


A titanium layer is formed on a dielectric layer. A TiN layer is formed on the titanium layer to act as a barrier layer. A rapid thermal annealing is performed. A tungsten layer is deposited by useing chemical vapor deposition with N.sub.2 plasma treatment. In a preferred embodiment, the temperature of the deposition ranges from 300 to 500 degrees centigrade. The gas pressure of the process is about 2 to 4 torr. The power of the plasma is about 300 to 800 Further, the treatment time of the N.sub.2 plasma ranges from 50 to 150 seconds. An etching back step is carried to etch a portion of the tuugsten layer.

An electrically connecting structure such as an interconnection for connecting elements between semiconductor devices is becoming more critical as the sizes of the devices are scaled down. Typically, the interconnection or other electrically conducting elements are widely used for providing specific conducting paths in an electrical circuit. In the process of forming the electrical conducting structure over an underlying layer, it is important that the surface of the underlying layer be free of any contamination, such as moisture, particles or oxides. Further, the surface of the underlying layer must be planar for subsequent layer deposition.
Tungsten is one of the common materials used in the formation of an electrical conducting structure. Before forming a tungsten layer over a underlying layer, a composition layer consisting of Ti and TiN layers must be formed along the surface of the underlying layer to act as a barrier layer. A rapid thermal annealing step is subsequently employed after the barrier layer is formed. However, the so called "micro-crack" phenomenon will occur after rapid thermal annealing. The phenomenon is attributed to stress release for the barrier layer. In the conventional method, the tungsten layer can be deposited by using chemical vapor deposition on the Ti and TiN composition layers. The reaction material for forming the tungsten layer includes WF.sub.6 and SiH.sub.4. Fluorine gas will be generated during the reaction. The fluorine penetrates through the micro-cracks and reacts with the titanium atoms. Thus, a by-product consisting of TiF.sub.x is generated and explodes out of the barrier layer and tungsten layer. This is referred to as the "volcano effect". This effect creates undesired tungsten particles on the surface of the tungsten layer.
What is required is a method of forming a tungsten layer free from particle contamination.

Method of forming a tungsten layer with N2 plasma treatment

Vanguard International Semiconductor Corporation