The present invention relates to a method for purifying polyalkylene carbonate. More specifically, a method for purifying polyalkylene carbonate is provided, which uses a multistage extraction column having the number of stages of at least 10 stages, using water for effectively removing by-products such as alkylene carbonate generated in a process for producing polyalkylene carbonate resin, thereby controlling the content of by-products to a certain level or less through a continuous operation, particularly, the extraction is performed at room temperature, thereby easily removing by-products in the resin without a high temperature volatilization.

Polyalkylene carbonate is a non-crystalline transparent resin and has only an aliphatic structure, unlike an aromatic polycarbonate, which is a similar type of engineering plastic. Polyalkylene carbonate is synthesized by a copolymerization reaction using carbon dioxide and epoxide as direct monomers (main raw materials) in the presence of a catalyst. Polyalkylene carbonate has advantages in that it has excellent transparency, elongation, and oxygen barrier properties, exhibits biodegradability, is completely decomposed into carbon dioxide and water during combustion, and leaves no carbon residue.
However, in the process of copolymerization using carbon dioxide and epoxide as monomers, approximately 3 to 20% of alkylene carbonate as a polymerization by-product is produced relative to the resin depending on the polymerization conditions. When the monomer is ethylene oxide, the polymerization by-product becomes ethylene carbonate (hereinafter referred to as EC). The ethylene carbonate serves as a plasticizer in the resin, and when the content is high, there is a problem that a glass transition temperature (Tg) of the resin is lowered, the resin is made very flexible, the strength is decreased, and adherence between the resins is increased. Consequently, when the resin is finally pelletized, the resin and the pellet are strongly adhered to each other, which serves to make handling difficult during processing. Therefore, for stably processing into a film or a sheet using a resin, the content of EC present in the resin should be controlled within an appropriate level through additional steps after polymerization.
Meanwhile, in order to remove polymerization by-products, methods such as devolatilization under high-temperature and high-vacuum conditions have been traditionally often used. The EC has a very high boiling point of 246° C., whereas polyalkylene carbonate is easily decomposed at 180° C. or higher and produces EC by a backbiting reaction. Therefore, when trying to remove the EC under ordinary high-temperature and high-vacuum conditions, an additional decomposition reaction is promoted, which finally makes it difficult to control the content of EC in the resin.
Therefore, a new method for minimizing the content of by-products such as EC in final resins is required.

Method for purifying polyalkylene carbonate


A display device includes field emission cathode apparatus for emitting electrons. A plurality of electron beams are formed from the field emission cathode apparatus. A screen, which has a phosphor coating facing the cathode receives the plurality of electron beams. The phosphor coating includes a plurality of pixels each corresponding to a different one of said plurality of electron beams. A grid electrode is disposed between the cathode and the screen for controlling the flow of electrons from the cathode. The field emission cathode includes extractor grid means, having a plurality of separately addressable portions associated with each of said plurality of pixels. A gamma transfer function between input data value and beam current is provided in order to emulate a conventional CRT. This can be achieved by use of a lookup table.

Flat panel electron beam displays comprise a cathode and an anode contained in an evacuated envelope. In operation, the cathode is held at a negative potential relative to the anode. Electrons are emitted from the cathode. The potential difference between the cathode and the anode accelerates the emitted electrons from the cathode towards the anode in a beam. A beam current thus flows between the anode and the cathode. In flat panel electron beam displays a matrix arrangement is disposed between the cathode and the anode. The matrix arrangement is formed by a pair of "combs" placed at right angles to each other. These are commonly referred to as rows and columns. Each pixel or subpixel lies at the intersection of a row and a column. Each of the combs has many separate elements which is comprised of either rows or columns. In operation, a control voltage is applied to each element of each of the combs. The control voltage applied to each element imposes an electrostatic force on the electron beam associated with that element whether it be a row or a column. The electron beam current associated with that element can be adjusted by adjusting the control voltage.
For displays that allow multiple levels of intensity to be displayed on the screen, the rows and columns perform distinct functions. The comb having rows (or horizontal lines) is used to set the bias conditions for the pixel, that is, it has a simple control voltage applied that switches the individual row conductors between an OFF (unbiased) state and an ON (biased) state. The circuit which provides this switching is simple and inexpensive. The comb having columns (or vertical lines) is used to control the brightness at which pixels which are biased ON will be displayed. The brightness is set at an analog level between being equivalent to the pixel being biased OFF and the maximum level which the display will support. The number of intermediate levels which are supported is determined by the circuits driving the columns. The analog drive circuits which provide this switching are relatively complex and expensive. In some displays the operation of the rows and columns may be transposed.
The analog drive circuits which drive the columns are usually implemented by the use of a Digital to Analog Converter (DAC) for each of the column conductors.
The display operates so that if an analog voltage from one of the column drivers (DACs) intersects with an OFF (or unbiased) row, then no beam current will flow, regardless of the analog output value of the DAC. If an analog voltage from one of the column drivers (DACs) intersects with an ON (or biased) row, then the pixel becomes active, and the beam current which flows will be determined by the DAC setting. It is the analog voltage from the DAC which determines how much beam current flows and hence, what intensity is displayed for that pixel. In a practical implementation, all of the DACs are driven in parallel with data for respective pixels in a given row, so that an entire row of data is presented simultaneously. The row which is active and displaying data propagates down the screen as the entire frame of data is constructed.
For a display having 1024 pixels in each row of the display, this means that 1024 separate DAC circuits are needed. The DAC circuits are relatively complex and expensive and the cost of these circuits is a significant proportion of the overall cost of the flat panel display. If a separate DAC is used for each of the three subpixels, associated with each of the three colours, that make up a pixel in a colour display, then 3072 DAC circuits are needed, which adds further to the overall cost of the flat panel display.

Device cathode with extractor grid for display

International Business Machines Corporation


The present invention relates to coated fullerenes comprising a layer of at least one inorganic material covering at least a portion of at least one surface of a fullerene and methods for making. The present invention further relates to composites comprising the coated fullerenes of the present invention and further comprising polymers, ceramics and/or inorganic oxides. A coated fullerene interconnect device wherein at least two fullerenes are contacting each other to form a spontaneous interconnect is also disclosed as well as methods of making. In addition, dielectric films comprising the coated fullerenes of the present invention and methods of making are further disclosed.

Fullerenes are broadly defined as the third form of the element carbon after diamond and graphite. Fullerenes are molecular solids that consist of fused six-membered and five-membered rings. Two general types of fullerenes may be described: Buckyballs and carbon nanotubes. Buckyballs have spherical structures and are typified by C60. Other spherical fullerenes include C70 and higher oligomers. Single walled carbon nanotubes (SWNTs) are elongated members of the fullerene family.
The interior cavity of a fullerene can accomodate an atom, molecule, or particle, depending on the volume circumscribed by the structure of the fullerene, to provide so-called doped fullerenes. Furthermore, fullerenes may be chemically functionalized by reacting the surface under suitable conditions to form either covalent, van der Waals or dipolar interactions with a chemical substituent.
SWNTs have come under intense multidisciplinary study because of their unique physical and chemical properties and their possible applications. The electronic characteristics of SWNT can be described as metallic or semiconducting; such characteristics deriving from the helicity and diameter of the SWNT. More importantly, it has been shown that these electronic properties are sensitive to the environment surrounding the SWNT. For example, it is well known that the presence of certain molecules, such as O2 or NH3, may alter the overall conductivity of SWNTs through the donation or acceptance of electrons. Such properties make SWNT ideal for nanoscale sensing materials. Nanotube field effect transistors (FETs), for example, have already been demonstrated as gas sensors. It is thought that selectivity in nanotube sensors can be achieved through the placement of specific functional groups on the nanotube surface; such groups having the requisite ability to selectively bind specific target molecules. Working against this goal is the fact that functionalization changes the electronic properties from that of a semiconductor or conductor to that of an insulator. Moreover, chemical functionaliztion of SWNT is not as of yet regiospecific. A further major obstacle to such efforts has been diversity of tube diameters, chiral angles, and aggregation states of the tubes. Aggregation is particularly problematic because highly polarizable, smooth sided SWNTs readily form bundles or ropes with van der Waals binding energy of ca. 500 eV per micrometer of tube contact. This bundling perturbs the electronic structure of the tubes and precludes the separation of SWNTs by size or type.
SWNT-based composites can provide excellent electronic and/or mechanical properties upon incorporation into a suitable matrix. Carbon nanotubes are excellent candidates for the fabrication of robust composites, and conducting polymers, due to their fascinating electronic and mechanical properties. Unfortunately, two issues must be overcome prior to development of large-scale applications. First, the SWNTs must be stable within a desired matrix. Second, the aggregation of SWNTs into ropes and bundles requires high loading that is uneconomic and represents a waste of materials.
The first of these issues requires that the SWNTs be protected from subsequent processing, e.g., oxidation. In addition, the formation of a stable tube/matrix interface is critical for composite applications. Surface treatments are required to ensure efficient tube-matrix interactions. Unfortunately, these treatments can result in the degradation of the tubes. The second of these issues requires that individual SWNTs (rather than bundles) be employed to maximize the impact of the SWNTs at the lowest possible loading.
It has been shown that individual SWNTs may be obtained encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw SWNTs in the presence of a suitable surfactant. See, O'Connell et al., Science 2002, vol. 297, pp. 593-596, incorporated herein by reference. Upon drying the micellular solution, however, bundles re-form. SWNTs have been encased in a wide range of organic materials. It would be desirable to fabricate individually coated SWNTs where the coating is retained in solution and the solid state. Of particular interest are dielectric materials such as silica, which may also be compatible with composite matrix materials. Silica is an example of an inorganic oxide.
Coating of SiO2 on multiwalled carbon nanotubes (MWNTs) has been reported. See Seeger et al., Chem. Phys. Lett. 2001, vol. 339, pp. 41-46, incorporated herein by reference. However, these coatings required a sol-gel type of reaction and extremely long reaction times on the order of 150 hours. Coatings have also been reported on SWNTs, but these require isolation of the tubes on a surface prior to reaction. It would be advantageous if there was a method by which individual fullerenes and individual SWNT could be coated under near ambient temperatures with reaction times on the order of a few hours, without the need for isolation on a surface prior to coating.
The classical sol-gel process for generating thin films of an oxide, such as silica, on substrates can be divided into three steps: First, preparation of a stable dispersion of colloidal oxide particles in a liquid, "sol formation"; Second, aggregation of the particles to encompass the liquid, "gel formation", and deposition of the resulting gel on the surface of the substrate; and Third, removal of the solvent by drying and/or heating. See Vossen, et al., Adv. Mater. 2000, vol. 12, pp. 1434-1437, incorporated herein by reference.
In contrast, the liquid phase deposition, "LPD", of silica from saturated fluorosilicic acid solutions involves the reaction of water with silica precursors that are solvated at the molecular level to generate silica gels that deposit onto the surface of the substrate. See Yeh, et al., J. Electrochem. Soc. 1994, vol. 141, pp. 3177-3181, incorporated herein by reference. Whereas film growth in the sol-gel method is largely dependent on the size of the initial colloidal particles and its influence on their aggregation, growth in the LPD method is more controlled since it continues layer by layer as more molecules react on the surface of the substrate. The important step in LPD is to provide an active site for growth to occur on a surface.
The semiconductor industry has targeted the development of the interlayer and intrametal dielectric for the next several generations of higher density, faster computer chips, as specified by the milestones set out in the International Technology Roadmap for Semiconductors (the ITRS). There is still no acceptable material or process that produces films with the desired values of low dielectric constant (k value) concurrently with optimum electro- and thermo-mechanical properties. Current processes are based either on sol-gel methods for film deposition and growth, or on low temperature chemical vapor deposition (CVD) of carbon or fluorine-containing silicon dioxide films. The k values achieved by these processes are in the range from ˜2.7 to greater than 3, still well above the maximum value of 2 required by the industry in order to meet the chip performance milestones identified in the ITRS.
Silicon dioxide (SiO2) forms the basis of planar silicon chip technology. Insulator coatings for electronic and photonic devices layers are most frequently formed by thermal oxidation of silicon (Si) in the temperature range 900 to 1200° C. SiO2 is also deposited by chemical vapor deposition (CVD) techniques at lower temperatures (200 to 900° C.) on various substrates. The growth of insulator films at low temperatures is very attractive for most device applications due to reduced capital cost, high output and freedom from technological constraints associated with the growth of dielectric thin films using conventional high-temperature growth/deposition techniques. Deposition of SiO2 insulator layers from solution is previously known using organo-metallic solutions. In this procedure, the insulator layer is applied onto the substrate either by dipping the substrate into the solution or by spinning the substrate after a small amount of the solution is applied onto the surface. In both cases the substrate is then placed in an oven to drive off the solvent.
Attempts to produce porous silicon dioxide have failed to produce films with isolated voids and uniform void size, resulting in poor process reproducibility and film quality. Such processes also require the use of heat to evaporate a solvent or other component from the film to create the voids, something not required by the present invention.
CVD (chemical vapor deposition) requires the pyrolysis or photolysis of volatile compounds to create chemical fragments that are deposited on the surface of a substrate. The temperature of substrate is sufficiently high to allow mobility of fragments on the growth surface. These fragments travel around the surface until they find thermodynamically stable sites to which they attach. In this way the quality of CVD films is usually high. Thus, CVD uses surface growth. If gas phase growth occurs, uniform films are not produced. Instead, nanoparticles can form, from which films form after agglomeration. The resulting film requires further thermal processing in order to become uniform. Disadvantages with CVD include the high temperatures required and the use of volatile compounds or low pressures. Each of these adds to the environmental load of the process. Sol-gel is a low temperature method. Precursor compounds are dissolved in solution and reacted with additional reagents (usually water or an acid) to give a gel. If a film or coating is required, then the gel must be spin-coated onto the substrate. Since most sol-gels consist of nanoparticles or clusters with a significant organic content, additional thermal or chemical treatments are required to form a true inorganic material.

Coated fullerenes, composites and dielectrics made therefrom


A centrifugal turbomachine comprising a casing, a rotor assembly comprising at least one centrifugal impeller for a fluid flowing from an inlet side to an outlet side of the impeller, and an eye seal extending between an impeller eye of the centrifugal impeller and the casing for preventing the fluid from leaking between the casing and the centrifugal impeller, wherein the eye seal comprises at least a first portion toward the inlet side and a last portion toward the outlet side of the impeller, the last portion being smaller in diameter than the first portion.

The present invention relates to centrifugal turbomachines, to centrifugal impellers for turbomachines and to the related production methods, particularly, but not exclusively, for oil and gas applications.
A centrifugal turbomachine is a rotary machine where mechanical energy is transferred between a working fluid and a centrifugal impeller. In oil and gas application, where the fluid is typically a gaseous fluid, centrifugal turbomachines include compressors and expanders. A compressor is a turbomachine which increases the pressure of a gaseous fluid through the use of mechanical energy. An expander is a turbomachine which uses the pressure of a working gaseous fluid to generate mechanical work on a shaft by using an impeller in which the fluid is expanded.
In uncompressible fluid, e.g., water, centrifugal turbomachines include pumps and turbines, which transfer energy between the fluid and the impeller in a way analogous to compressors and expanders, respectively.
In general, in all cases, the working fluid exchanges energy with the centrifugal machine by flowing in the centrifugal impeller along a radial outward direction, oriented from an axis of rotation of the impeller to a peripheral circumferential edge of the impeller.
In particular, the centrifugal impeller of a compressor turbomachine transfers the mechanical energy supplied by a motor that drives the turbomachine to the working gaseous fluid being compressed by accelerating the fluid in the centrifugal impeller. The kinetic energy imparted by the impeller to the working fluid is transformed into pressure energy when the outward movement of the fluid is confined by a diffuser and the machine casing.
Centrifugal turbomachines can be fitted with a single impeller, in which case they are frequently referred to as single stage turbomachines, or with a plurality of impellers in series, in which case they are frequently referred to as multistage centrifugal turbomachines.
A prior art embodiment of a multistage centrifugal compressor 100 is illustrated in FIG. 1, in an overall section view, and in FIGS. 2 and 3, in more detailed section views. Compressor 100 is included in a casing 102 within which is mounted a shaft 101 and a plurality of impellers 110. The shaft extends along an axis of rotation X of compressor 100. The shaft 101 and impellers 110 are included in a rotor assembly 103 that is supported through a couple of bearings 150 and 160, which allow the rotor assembly to rotate around the axis of rotation X. The multistage compressor 100 comprises a plurality of stages 107 (seven stages 107 in the embodiment in FIG. 1), each stage 107 including one impeller of the plurality of impellers 110 and a portion of the casing 102, where an inlet duct 170 upstream the impeller 110 and an outlet duct 180 downstream the impeller 110 are provided. The impeller 110 has a typical closed design configuration including an impeller hub 113, which closely encircles the shaft 101, and a plurality of blades 108 extending between a rear impeller disc 114 and a front shroud 119. The impeller 110 comprises an inlet low-pressure side 111 defined by an impeller eye 115 on the front shroud 109 and an outlet high-pressure side 112 defined by a peripheral circumferential edge of the impeller 110.
Through operation of the impeller 110, each stage 107 of the multistage compressor 100 operates to take an input process gas flowing along the inlet duct 170, to drive the gas from the inlet low-pressure side 111 to the outlet high-pressure side 112 of the impeller 110 and to subsequently expel the process gas through the outlet duct 180 at an output pressure which is higher than its input pressure.
The process gas may, for example, be any one of carbon dioxide, hydrogen sulfide, butane, methane, ethane, propane, liquefied natural gas, or a combination thereof.
An impeller eye seal 120 is provided between the impeller eye 115 of each centrifugal impeller 110 and the casing 102, in order to prevent the fluid from leaking in the space between the casing 102 and the impeller 110, from the outlet high-pressure side 112 to the inlet low-pressure side 111. The casing 102 includes an inlet ring 104 facing the impeller eye 105 and provided with a cavity for housing the impeller eye seal 120.
The impeller eye seal 120 is of the labyrinth type with a plurality of teeth 121a-e (five teeth 121a-e in the embodiment in FIGS. 1-3). Each tooth 121a-e extends radially towards the axis of rotation X and circumferentially around the axis of rotation X. The envelope profile of the teeth 121a-e is conical in shape with a mean diameter 122. The eye seal 120 is mounted on a housing in the casing 102 and placed in such a way that a first tooth 121a toward the inlet low-pressure side 111 is smaller in diameter than a last (fifth) tooth 121 e toward the outlet high-pressure side 111. To match the shape of impeller eye seal 120, the impeller eye 115 is provided with a stepped region 116 comprising a plurality of steps 117a-e (five steps 117a-e in the embodiment in FIGS. 1-3), each facing a respective tooth of the plurality of teeth 121a-e. The plurality of steps 117a-e includes a first step 117a toward the inlet low-pressure side 111 having a diameter 123a which is smaller than the diameter 123e of a last (fifth) step 117e toward the outlet high-pressure side 112 of the impeller 110.
Fluid leakages through the eye seal 120 must be reduced as much as possible for the reason that the portion of fluid leaking from the outlet to the inlet side has to be compressed again through the impeller, thus reducing the efficiency of the turbomachine.
An impeller having the same design of impeller 110 can be used also in an expander, the main difference being the fact that the gaseous fluid expands in the impeller, i.e., the inlet side, corresponding to the impeller eye, is the high-pressure side while the outlet side, corresponding to the peripheral circumferential edge is the low-pressure side. In an expander the impeller eye seal prevents the fluid from leaking in the space between the casing and the impeller, from the inlet high-pressure side to the inlet low-pressure side. Fluid leakages through the eye seal must be reduced as much as possible also in an expander, for the reason that the portion of fluid leaking from the inlet to the outlet side does not flow through the impeller and therefore does not contribute to generate mechanical work on the shaft, thus reducing the efficiency of the turbomachine.
It would be desirable to design and provide an improved sealing system for reducing the leakage flow through the impeller eye of a centrifugal impeller.


A ventilating window for ventilating the interior of a building or a structure such as a vehicle in a natural and gentle manner. A ventilating window for the exhaust of air is provided with a mechanism for automatically opening a window casement when the atmospheric pressure inside the window is higher than the outside atmospheric pressure, thereby dispensing with forced exhaust using a fan or the like. A ventilating window for the supply of air is provided with a mechanism for automatically closing a window casement when the atmospheric pressure outside the window is higher than the inside atmospheric pressure, thereby preventing a strong wind from blowing into the interior. A ventilating window for both exhaust and supply of air is provided with both such opening mechanism and closing mechanism.

1. Field of the Invention
The present invention relates generally to a ventilating window for a structure and particularly to the structure of a window for gently ventilating the interior of a structure, or a building, by effectively utilizing natural wind blowing against the building from the exterior or a difference in temperature or atmospheric pressure between the interior and exterior of the building.
2. Related Background Art
Recent buildings, even wooden buildings, are highly airtight and various studies have been made about indoor ventilation. As indoor ventilation methods are known natural ventilation and artificial ventilation.
Natural ventilation methods are broadly classified into ventilation by wind force which uses as a driving force a wind pressure applied to the exterior wall of a building and gravitational ventilation which uses as a driving force a difference in air density based on a temperature difference between the interior and exterior of a building.
The most typical example is such a ventilating duct such as a roof ventilator, which mainly utilizes a suction force induced by external wind. More particularly, a negative-pressure portion is created by wind force to suck the interior air.
However, in the case of a ventilating duct such as a roof ventilator, it is necessary to give a special consideration in the execution of work such as forming an opening in the roof of a building.
On the other hand artificial ventilation uses a mechanical force such as a blower or the like for the intake and/or exhaust of air.
Artificial ventilation using a mechanical force such as a blower easily affords an appropriate ventilation volume constantly, but the electric power consumption of the blower when used over a long period becomes extremely large.

Tateyama Aruminiumu Kogyo Kabushiki Kaisha


An apparatus for beverage brewing using heated liquid to infuse a beverage brewing substance during a brewing cycle. The apparatus includes a brew chamber which is positioned for communication with a reservoir having a filter positioned between the brew chamber and the reservoir. A quantity of beverage brewing substance is placed in the brew chamber and a quantity of heated water is placed in the reservoir. A pumping device pumps the water in the reservoir to the brew chamber to infuse the beverage brewing substance and produce a brewed beverage. The brewed beverage created in the brew chamber drains through the filter between the brew chamber and the reservoir and is captured by the reservoir. The brewed beverage and any remaining heated water are recirculated through the beverage brewing substance in the brew chamber for a period of time. At a desired period in the brewing cycle, a valve connected to the reservoir is operated to open the reservoir and drain the brewed beverage therefrom. The pump device drains the recirculation path between the reservoir and the brew chamber and forces air through the spent beverage brewing substance thereby expelling moisture from the spent beverage brewing substance. A plunger is used to enclose the beverage brewing substance in the brew chamber and deposit water from the pump to infuse the brewing substance. At the end of the cycle, the brew chamber is displaced from the filter and reservoir and the plunger expels the spent beverage brewing substance.

The present invention relates to beverage brewing apparatuses and more particularly to beverage brewing apparatuses which quickly and efficiently brew a desired quantity of beverage.
A variety of beverage brewing apparatuses are available which incorporate a number of beverage brewing operation in a single apparatus. An example of such a beverage brewing apparatus can be seen in U.S. Pat. No. 5,134,925 to Bunn et al. The Bunn et al. reference shows a beverage brewing apparatus which brews a desired quantity of beverage by way of an infusion type brewing process. In Bunn et al. a beverage brewing substance is placed in a brew chamber and heated water is introduced into the brew chamber to infuse the substance. A brewed beverage is drained through a reusable filter material and dispensed into an appropriate container. The Bunn et al. apparatus provides a rather quick and efficient high-quality brewed beverage with a high degree of automation and minimum human interaction. The device as shown in Bunn et al., however, uses gravity flow brewing principles to brew the desired beverage from the brewing substance.
It has been found to be desirable to further accelerate the beverage brewing process to produce a desired quantity of brewed beverage within a shorter period of time. It is also desirable to maintain the degree of automation and, especially, maintain a high quality and consistency of flavor of the brewed beverage produced by such a system. Additionally, it would be desirable to brew a beverage and dispose of the spent brewing substance in a clean and efficient manner.
While it has been stated that it would be desirable to quickly produce a brewed beverage, this is not to say that a beverage brewing system meeting these desirable conditions would utilize espresso brewing principles. Espresso brewing principles are substantially different than drip or gravity brewing principles as used in Bunn et al. Espresso principles produce a brewed beverage by infusing a quantity of brewing substance in a pressure chamber with pressurized water. For example, when brewing drip coffee, a gravity system will utilize approximately two tablespoons of ground coffee for each six ounces of water. Espresso brewing utilizes approximately two-thirds of the ground coffee (having a substantially finer particulate size) and infuses the ground coffee with pressurized water to produce approximately one to two ounces of espresso brew.
The espresso principles have been used to quickly produce a desired quantity of coffee at a desired strength for consumption either as an espresso drink or to be diluted with hot water to produce a beverage similar to a gravity or drip brewed beverage. A problem arises with the espresso techniques and automation in that it can be difficult to remove the spent coffee grounds from the brewing chamber.
The following list is provided by way of background to show a variety of beverage brewing devices.
______________________________________ Patent No. Inventor Issue Date ______________________________________ 4,993,315 Huber et al. 02/19/1991 4,767,632 Meier 08/30/1988 4,703,686 Siegfried 11/03/1987 4,612,850 Kanazashi et al. 09/23/1986 4,110,221 Moser 08/29/1978 3,683,790 Black et al. 08/15/1972 3,662,675 Ollander 05/16/1972 3,288,049 Schmid et al. 11/29/1966 2,529,395 Humel 11/07/1950 ______________________________________


There is disclosed a ball screw integrated type linear movement guiding unit which achieves a stable, smooth operability, and can meet with a high-load and high-rigidity application. Each of ball return passageways which respectively provide ball-circulating passageways of a ball screw system and a linear movement guiding system in the unit is constituted by an axial through hole much larger in diameter than a ball, and a cylindrical member of a synthetic resin which has an inner diameter generally equal to the diameter of the ball and is press-fitted in the through hole. With this construction, the rolling of the balls is effected smoothly. Further, even if the length of a nut is increased to meet with a high-load and high-rigidity use, the ball return passageway can be easily formed.

1. Field of the Invention
This invention relates to a ball screw integrated type linear movement guiding unit preferably suited for use in an operating arm of a robot, an X-Y table and so on, and more particularly to a low-cost ball screw integrated type linear movement guiding unit in which a ball return passageway constituting a ball circulating system is improved to provide a smooth operability even for a high-load and high-rigidity application.
2. Prior Art
One conventional ball screw integrated type linear movement guiding unit is disclosed, for example, in Japanese Utility Model Laid-Open Application No. 2-12554.
This conventional construction comprises a male-threaded shaft having a spirally extending ball screw groove in an outer surface thereof, and a guide rail embracing the male-threaded screw shaft in parallel relation thereto, the guide rail having axial ball-rolling grooves in its side surfaces. A nut is threadedly engaged with on the male-threaded screw shaft via a number of balls rolling through the groove, and ball-rolling grooves opposed respectively to the ball-rolling grooves of the guide rail are formed respectively in the opposite side surfaces of the nut. Through the rolling movement of a number of balls in the opposed ball-rolling grooves, the nut is guided to be linearly axially moved in the forward/rearward direction.
As a ball-circulating passageway of the ball screw system which guides and circulates the balls rolling in the ball screw groove of the ball screw, there is provided a ball-circulating tube of a U-shape incorporated in the upper portion of the nut. On the other hand, as a ball-circulating passageway of a linear movement guiding system which guides and circulate the balls rolling in the opposed ball-rolling grooves of the guide rail and the nut, there are provided through holes which are slightly larger in diameter than the ball and are formed in a thickened portion of the nut, the through hole extending parallel to the ball-rolling grooves. Curved passageways of a semi-doughnut shape each interconnecting the through hole and the ball-rolling grooves are formed in each of end caps mounted respectively on the front and rear sides of the nut.
However, in the above conventional ball screw integrated type linear movement guiding unit, in order to form the ball-circulating passageway of the linear movement guiding system for guiding and circulating the balls rolling in the opposed ball-rolling grooves of the guide rail and the nut, the axial through hole is drilled in the thickened portion of the nut, and the balls are passed directly through this hole serving as a ball return passageway. Therefore, because of the roughness of the drilled hole surface, scales formed on the drilled hole surface at a subsequent heat treatment of the nut, a step on a joined portion of the hole, and so on, a smooth passage of the balls is prevented, which results in a problem that the circulation of the balls becomes unstable.
Further, even if it is intended to increase the ball load passageway of the linear movement guiding system for a high-load and high-rigidity application, the length of the nut in its axial direction is increased, and therefore the length of the ball return passageway must also be increased. As a result, the hole having a high length-diameter ratio must be formed, and therefore there has been encountered a problem that the length is limited in this respect.
In order to overcome the difficulty with the working of the ball return passageway of the ball system integrated type linear movement guiding unit, the Applicant of the present application has earlier made a proposal in which the diameter of the through hole is made considerably larger than the diameter of the ball so as to improve the precision and efficiency of the working, and a pipe is press-fitted into this through hole to form the ball return passageway (U.S. Pat. No. 4,648,726).

Ball screw integrated type linear movement guiding unit


An apparatus and method for generating swath lines including compensation for sloping terrain in a field for use in an automatic guidance system of a work machine. The swath lines are created as a function of the position, elevation and/or orientation of the work vehicle.

Off road work vehicles in the agricultural, mining and construction fields, such as tractors, and the like, have traditionally operated with manual steering. Improvements in control system design and related position sensing technology, such as global positioning systems (GPS), including differential correction systems, as well as real time kinematic (RTK) satellite navigation have led to an increase in the use of automatic guidance control systems for these vehicles. The combination of improved navigation input signals precisely identifying vehicle position and speed with sophisticated on board vehicle electronic control systems allows for automatic guidance systems capable of steering the vehicle with a high degree of accuracy when traversing terrain.
To provide this control, the prior art teaches using satellite positioning information by an onboard vehicle navigation control system to accurately determine and control a vehicle's position while operating in a field. A preplanned route, based on information previously known about the terrain of the field, or a control system generated route may be used. The control methods are well known in the art, and may involve multiple position transmitters or receivers, with various signals used to derive vehicle location, elevation, direction of travel or heading, and speed.
The task of precision guidance of an agricultural vehicle involves not only accurately determining vehicle position in a field, but also defining an efficient array of paths to be followed by the vehicle that will, in conjunction with the swath of an element associated with the vehicle, create an overall swath pattern that efficiently and effectively covers the crop area of a field. The pattern must be located and oriented on the field, and the physical characteristics and limitations of the vehicle and coupled element must be identified and provided to the navigation system. Element or header width, location of the element or header with respect to the vehicle, and limitations on the vehicle and associated element movement, such as minimum turning radius, must also be considered. With this information it is possible to define a series of swath lines for the vehicle to travel in an attempt to cover all cultivatable portions of a field without unnecessary gaps or overlaps.
Calculating the series of paths needed to cover an area without substantial gaps or overlaps is relatively straightforward for straight paths on level terrain; however, not all fields can be covered in this manner. Many fields require the use of paths having a curvature that varies along at least some portion of its length, whether to follow irregularly shaped boundaries, avoid obstacles within the field, follow topographic contours of the ground, implement agronomic farming practices, or contour the ground for irrigation. Such conditions preclude a complete reliance on geometrically predefined paths, such as straight lines or constant radius curves. In addition, many fields include hills or valleys of sufficient slope to create errors in swath pattern calculations based on an assumption of flat terrain. These errors have been seen to cause gaps or overlaps between swaths in some cases.
Previous attempts to correct for errors due to slopes in the terrain use GPS data to determine the slope of the terrain and make swath line corrections as a vehicle traverses the swath. Reference in this regard Keller et al., U.S. Pat. No. 6,463,374 which discloses a method for compensating for a decrease in the effective length of a sprayer rig boom when the sprayer rig is operating on sloped terrain. Based on the disclosure, and particularly FIG. 8A of that patent, it appears that swath path corrections are based on the slope of the terrain at the presently driven swath path. In other words, the system makes corrections to a swath line as it is driven based on the slope of the terrain immediately behind the vehicle (because of computation delays as explained at column 10, lines 22-25). Thus the system is making adjustments to the vehicle course as it traverses the swath and basing those adjustments on the computed slope information associated with the terrain within the same swath.
Practical considerations limit the utility of the system and method of the Keller patent. For example, in an articulated work vehicle, such as a tractor coupled with an element, the articulated portions of the vehicle may not rigidly follow the front portion of the work vehicle creating slippage at the articulated joints of the vehicle and coupled element. This slippage may be due to anticipated conditions, such as turning the work vehicle, or due to unanticipated conditions, such dry or muddy terrain, variations in moisture in hilly terrain, sharpness of the element, tire wear, and other conditions under which the element is not rigidly aligned with the front of the vehicle. This is especially important to note for sloping terrain because of slippage of the element down the slope. The operator may need to manually steer the vehicle to achieve the desired swath line to compensate for slippage. Swath line corrections according to the method of this patent may be ineffective either because they may not be implemented quickly enough to align the articulated portion of the vehicle to the desired swath line, or they will have been overridden by the manual steering of the operator.
Finally, swath lines are typically depicted on a map available to the operator for use during operation. Because the method and system of the referenced patent adjusts and executes the swath path contemporaneously, the swath line is not available to be depicted on a map for the operator. For this reason, the swath line should generally be calculated prior to the time the vehicle engages the swath rather than as the vehicle engages the swath as done in the referenced patent. Thus, what is sought is an apparatus and method to generate swath lines and swath patterns that include swath corrections to compensate for variations in the slope of a field which overcomes at least one of the problems, shortcomings or disadvantages set forth above.

Swath line creation including slope compensation for an automatic guidance system of a work vehicle


A leg muscle stretching and conditioning device in the form of a belt made from flexible material, and a pad member having a slot through which the belt is passed. The pad member is slidable along the belt and preferably includes a plurality of alternating ridges and grooves along its lower surface to permit the pad member to be slidable over a wide variety of surfaces. In use, the user applies one foot on the belt to hold the belt in position and to prevent movement of the belt in a direction along the belt longitudinal axis. The other foot of the user is placed on the pad member so that the user's heel is received within a recess formed on the top surface of the pad member. This foot is moved to convey the pad member along the belt and support surface employing the frictional force between the pad member lower surface and the surface over which the pad member is moved to insure stability during performance and to guarantee gains achieved. The belt and pad member are substantially flat, for use on a flat surface, so that a user executing a split maneuver has his body fully supported by the surface on which the invention is supported.

1. Field of the Invention
The present invention relates to a device for exercising and conditioning the leg muscles by permitting the user of the device to stretch the leg muscles in a controlled manner to enable the individual to more skillfully and to more effectively practice the martial arts. More particularly, the present invention relates to an easy-to-manufacture leg muscle stretching device suitable for martial arts students, dancers, and athletes, and that is of simple construction, inexpensive, portable, and convenient to use in a number of locations.
2. Description of the Related Art
Devices for exercising the leg muscles have been known for some time. For example, U.S. Pat. Nos. 1,998,226; 2,224,103; 3,966,204; and 4,889,336 each disclose elastic-type bands or cords of different shapes and forms for performing various types of leg muscle, arm muscle, and body muscle exercises. Similarly, U.S. Pat. Nos. 4,277,062; 4,877,239; 4,988,096; and 5,004,228 each show non-elastic leg muscle exercise devices, either using weights against which the leg muscles operate, or by pitting arm and leg muscles against each other by a combined leg and arm arrangement.
In addition to the above-identified patents U.S. Pat. No. 4,132,404, which issued on Jun. 2, 1979, to Raymond L. Wilson, shows a leg muscle stretching exercise device in which a pair of platforms having casters are connected by a rope. The user places his feet on respective ones of the linearly and pivotally movable platforms, which are elevated above the ground and are movable toward and away from each other by the user flexing his leg muscles to move his feet together and apart while they are on the platforms. The rope extends between the platforms and defines the maximum spacing between them to limit the extent of leg movement. However, because of the elevation of the platforms above the ground surface, the device lacks complete support for the body of a user when executing a "Chinese split" or a "dancer's split."
Another patent that discloses leg muscle stretching apparatus is U.S. Pat. No. 4,506,884, which issued on Mar. 26, 1985, to Stuart M. Hankin. That patent discloses a bulky structure including a two-piece base member having opposed, U-shaped support handles, and a pair of carts that are movable toward and away form each other along the base member.
Although the previously-known devices are generally satisfactory, the band-type devices are not especially effective for the leg muscle conditioning movements particularly desired by martial arts and dance students. The two devices disclosed in the Wilson and Hankin patents identified above are cumbersome to use, they are bulky and inconvenient to transport from place to place, and they are expensive to produce.
It is an object of the present invention to overcome the shortcomings of the known devices.


Nanometre scale particles (3) e.g. of Au are deposited on a Si substrate (2) with a SiO.sub.2 surface layer (1) provided with receptor sites (4) of a first electrical polarity by treatment with APTMS solution. The Au particles (3) have a surface charge (5) of a second opposite polarity e.g from surface adsorbed citrate ions, such that they are attracted to the surface sites on the substrate. The deposited Au particles are then released from the surface sites such that the particles move over the substrate and coalesce into a low dimensional aggregated structure. The aggregated structure may form at a surface irregularity on the surface of the substrate. The structure may be used in a quantum electronic device such as a single electron transistor.

Quantum electronic devices which manipulate the flow of individual electrons, are known and reference is directed to W. Chen, H. Ahmed and K. Nakazato, Appl. Phys. Lett. vol. 66, 3383 (1995). These prior devices make use of so-called quantum dots which are conductive islands, constructed on the nanometre scale which exhibit Coulomb blockade to single electron tunnelling. According to this effect, the charging energy of the island is greater than the surrounding thermal energy, so that once charged by the entry of a single electron, no further electrons can enter the dot until an electron leaves. Quantum electronics devices use this effect to manipulate single electrons entering and leaving a quantum dot, and typically consist of a metal or semiconductor quantum dot in which electrons are localised, dielectric tunneling barriers through which single electrons enter or leave, and electrodes which either electrostatically bias the dot or supply electrons to the dot through the barriers.
A general discussion of the Coulomb blockade effect for such a system is given in Hermann Grabert and Michel H. Devoret, "Single Charge Tunneling" (Plenum Press, New York, 1992) pp. 1-3. From this, it will be understood that there are two basic requirements for realising the Coulomb blockade effect in a single electron device, as follows: EQU E.sub.c =e.sup.2 /2CkT, (1) EQU R.sub.T R.sub.K =h/e.sup.2 (2)
where T is the device operation temperature, R.sub.T is a tunneling resistance, R.sub.K =h/e.sup.2 is the resistance quantum, and E.sub.c =e.sup.2 /2C is the energy required to place an electron at a localised electronic state in the dot. Here, the capacitance C is defined as a constant that relates the energy of the localised state and its spatial extent i.e. the geometrical shape of the charge distribution. The capacitance C is easily defined in the case of metal clusters, and is also definable in the case of semiconductor quantum dots. Reference is directed to M. Macucci, Karl Hess and G. J. Iafrate, "Electronic Energy Spectrum and the Concept of Capacitance in Quantum Dots", Phys., Rev. B, vol. 48, p. 17354 (1993).
It is desirable that a practical single electron device be operable at room temperature i.e. with T=300.degree. K. This implies from criterion (1) listed above that the capacitance C should be very small, namely C3.times.10.sup.-18 F.
The capacitance C can be designated as the sum of two different capacitances, as follows: EQU C=C.sub.S +C.sub.e
where C.sub.S is known as the self-capacitance and is constituted by the capacitance between the island and infinity. C.sub.e is the capacitance between the dot and the surrounding electrodes of the device. When the dot diameter becomes smaller than 10 nm, the self-capacitance C.sub.S mainly determines the total capacitance C as it is much larger than the other capacitances C.sub.e. Therefore, in order to ensure room temperature operation, the dot size should be reduced below 10 nm. However, devices with a dot size of less than 10 nm cannot be fabricated readily using conventional electron beam lithography as this is smaller than the state of the art techniques can readily achieve.
It is known that nanometre scale particles can be prepared chemically, with diameters of less than 10 nm, such as colloidal particles and molecular clusters. For example, gold colloidal particles in citrate gold sols have been prepared in a size range from 2 nm to 100 nm. Reference is directed to N. Uyeda, M. Nishino, and E. Suito, J. Colloidal and Interface Science, vol. 43, p. 181 (1973). Also, ligand-stabilised Au.sub.55, clusters with a gold metal core size of 1.4 nm have been reported--see G. Schon and U. Simon, Colloid Plym. Sci., vol. 273, pp. 101-127 and pp. 202-218 (1995). One of the significant features of these materials is their well defined particle size distribution. In the case of non-dispersed colloidal Au particles as reported by Uyeda et al supra, the size distribution has a 10% standard deviation. In the case of molecular clusters, the size distribution is determined at an atomic-scale accuracy. The average diameters of these nano-scale particles are determined by the parameters of the chemical reactions that form the particles, such as the volume ratios of starting material solutions. The particle formation reactions proceed spontaneously according to the macroscopic reaction parameters and they are free of the size limitations that arise in conventional lithographic quantum dot fabrication.
A method of coating colloidal particles on metallic oxide surfaces has been known since the 1960's and reference is directed to R. K. Iller, Journal of Colloid and Interface Science, vol. 21, pp 569-594 (1966). Also, Au particle deposition on a metal oxide surface using a silane coupler was reported by A. Doron, E. Katz and I. Willmer, Langmur, vol. 11, pp 1313-1317 (1995). However, a problem with this technique was that particle coagulation occurred.
The application of cluster chemistry to single electron device fabrication is described in D. L. Klein, P. L. McEuen, J. E. B. Katari, R. Roth & A. P. Alivisatos, Pll. Phys. Lett. 68, 2574 (1996). A nanometre scale gold particle ligated alkane chains was used as a tunnel barrier. The particle was captured in a lithographically defined 5-nm gap between metal electrodes on a substrate, with limited reproducibility. This approach required complex lithographic techniques and did not use the self assembly techniques that can be achieved with cluster chemistry.
In copending EP- A-0788149 filed on Feb. 5th 1996 there is described a method of depositing nanometre scale gold particles onto a substrate in a monolayer with a controlled inter-particle spacing, suitable for use in quantum effect electronic devices. In our copending EP 96308283.9 filed on Nov. 15, 1996 and corresponding U.S. Ser. No. 08/958845 filed on Oct. 28th 1997, treating the monolayer of gold particles with an ethanolic solution of dithiol is described, to allow further overlying monolayers of the gold particles to be deposited. However, for some devices, it would be desirable to assemble nanometre scale particles in more closely packed structures such as wires, and to simplify the electrical connection of the particulate structure to other features of the device.

Method of depositing nanometer scale particles


Processes for preparing amino alcohols or salts thereof and sulfonamide substituted alcohol compounds are provided. Desirably, the sulfonamide substituted alcohol compounds are heterocyclic sulfonamide trifluoroalkyl-substituted alcohol compounds or phenyl sulfonamide trifluoroalkyl-substituted alcohol compounds.

This invention relates to inhibitors of beta amyloid production, which have utility in the treatment of Alzheimer's disease.
Alzheimer's Disease (AD) is the most common form of dementia (loss of memory) in the elderly. The main pathological lesions of AD found in the brain consist of extracellular deposits of beta amyloid protein in the form of plaques and angiopathy and intracellular neurofibrillary tangles of aggregated hyperphosphorylated tau protein. Recent evidence has revealed that elevated beta amyloid levels in the brain not only precede tau pathology but also correlate with cognitive decline. Further suggesting a causative role for beta amyloid in AD, recent studies have shown that aggregated beta amyloid is toxic to neurons in cell culture.
Heterocyclic- and phenyl-sulfonamide compounds, specifically fluoro- and trifluoroalkyl-containing heterocyclic sulfonamide compounds, have been shown to be useful for inhibiting β-amyloid production.
What is needed in the art are alternate processes for preparing sulfonamide compounds, which are useful for inhibiting β-amyloid production, and the intermediates thereof.

Methods for preparing sulfonamide substituted alcohols and intermediates thereof


A method and circuit for performing a monotonic digital calibration of a pipeline analog-to-digital (A/D) converter calibrates each stage of the pipeline A/D converter while using the actual input A/D converter of the stage then being calibrated. The digital output from the stage is converted to an analog signal (e.g., integrated) and fed back for use as the analog input to the stage. This ensures that the digital output from the stage has a symmetrical waveform and that the analog input voltage to the stage remains at the input threshold level. The remaining downstream pipeline A/D converter stages are then used to measure the levels of the binary residue voltage corresponding to the two states of the binary stage output so that appropriate calibration data can be generated and stored for use in calibrating that stage. By repeating this process for each successive upstream pipeline A/D converter stage the entire pipeline A/D converter can be calibrated to help ensure the monotonicity of its A/D conversion.

1. Field of the Invention
The present invention relates to pipeline analog-to-digital (A/D) converters, and in particular, to digital calibration techniques for such converters.
2. Description of the Related Art
Referring to FIG. 1, a typical stage 10 of a conventional pipeline A/D converter includes a sample and hold circuit 12, an A/D conversion circuit 14, a digital-to-analog (D/A) conversion circuit 16, a signal combining circuit 18 and an output buffer amplifier 20, all interconnected substantially as shown. By connecting N such stages 10 serially together a pipeline A/D converter is formed. A clock signal 9 synchronizes the operations of the sample and hold circuit 12, A/D converter 14 and D/A converter 16.
The analog residue signal 11 from the immediate upstream stage (i+1) is sampled and held by the sample and hold circuit 12. This analog sample voltage 13 is converted to a digital signal 15 (D.sub.i) by the A/D converter 14. This digital signal 15 is provided as the binary bit information for that stage (i) and is also converted back to an analog signal by the D/A converter 16. This analog signal 17 is summed with the original analog sample voltage 13. The resulting sum voltage 19 is then buffered by the output amplifier 20 to provide the residue voltage signal 21 for that stage 10. (A typical voltage gain for the output amplifier 20 is two.)
Referring to FIG. 2A, the A/D converter 14 can be implemented with a voltage comparator 14a which compares the sample voltage 13 to a reference voltage 13r. Referring to FIG. 2B, the D/A converter 16 can be implemented with a latching multiplexor 16a which, in accordance with the digital signal 15, selects between negative 15n and positive 15p analog voltages which are equal in magnitude for outputting as the analog voltage 17 to be summed with the sample voltage 13.
Such analog processing stages for pipeline A/D converters (often referred to as algorithmic A/D converters) have inherent imperfections which negatively affect the linearity and, therefore, the accuracy of such converters. For example, the number of linearity bits is determined by the native matching of the passive components and is usually limited to eight or ten bits. While it is possible to provide various forms of trimming of the analog circuitry which have been proven to work up to 16 bits of accuracy, such trimming procedures are very difficult and expensive.
Accordingly, a commonly used alternative approach is that of digital calibration and correction. In such an approach, the errors attributed to the analog components are identified and compensated within the digital domain. Examples of the techniques used in this approach can be found in the following references: S-H. Lee and B-S. Song, "Digital-Domain Calibration of Multistep Analog-to-Digital Converters," IEEE Journal of Solid-State Circuits, Vol. 27, No. 12, December 1992, pp. 1679-88; and A. N. Karanicolas, H-S. Lee and K. L. Bacrania, "A 15-b 1-Msample/s Digitally Self-Calibrated Pipeline ADC," IEEE Journal of Solid-State Circuits, Vol. 28, No. 12, December 1993, pp. 1207-15; the disclosures of which are incorporated herein by reference.
A major concern about such digital calibration and correction algorithms is that of the monotonicity of the transfer function. It has been shown that any linear correction algorithm with multiple internal representations of the same output code cannot guarantee the monotonicity of a converter transfer function. It has also been shown that local discontinuities in the monotonicity can occur within the output code even after digital correction.
Whereas the presence of a few signal states where the monotonicity has a local discontinuity may be acceptable in some applications, many closed loop control systems require virtually absolute monotonicity in order to avoid limit cycles. Further, local discontinuities in the monotonicity tend to be very difficult to detect by testing, can propagate toward the most significant bit and cannot be avoided by truncation since their positions are not known in advance.
As is well known, a common conventional digital calibration and correction technique involves the digital calibration of all of the transitions within the residue signal transfer characteristics. An analog input signal equal to the transition voltage is applied at the input of each stage and a decision is forced on both sides of such transition voltage. The resulting analog residue voltage is then measured by the remaining stages within the pipeline (assumed to be already calibrated or ideal). Based upon such measurements, correction coefficients for each transition are then stored in memory. Accordingly, each calibration step is equivalent to performing a digital shift of all of the residue segments along a common line (the ideal linear transfer characteristic).
Initially such a calibration algorithm may appear to preserve overall monotonicity since each step in the calibration procedure is monotonic. Indeed, this may be true if the analog calibration voltages are precisely at the exact voltage transition points. However, due to different offsets in the individual voltage comparator circuits, the actual transition points are offset, or shifted, from their ideal position. These offsets in the transition point, when combined with the inherent gain errors, lead to a calibrated transition which is not precisely equal to the actual transition gap. Therefore, the overall transfer characteristic has discontinuities in its monotonicity.
Accordingly, it would be desirable to have a digital calibration algorithm which truly preserves overall monotonicity of its transfer characteristic.

Apparatus and method for monotonic digital calibration of a pipeline analog-to-digital converter


A method of forming a semiconductor structure. The method comprises forming a high-k dielectric material, forming a continuous interfacial material over the high-k dielectric material, and forming a conductive material over the continuous interfacial material. Additional methods and semiconductor structures are also disclosed.

Various techniques are known in the art of forming a conductive material over a substrate during fabrication of devices in integrated circuitry. Such techniques include atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and other known deposition processes. ALD, CVD, PECVD, and other thin film deposition processes use volatile precursors to form conductive materials of a desired chemical composition on a substrate surface.
Often, the conductive material to be formed is a metal, metal oxide, or a metal nitride material. There may be several possible methods of forming such a material with a particular chemical composition on a substrate surface, however, each method may result in different physical or chemical properties of the as-deposited material. Varying deposition conditions, such as deposition temperature or precursors, may alter the capacitance, leakage current, resistance, or breakdown voltage of the as-deposited material. For instance, using a halogen-containing metal precursor, such as titanium tetrachloride (TiCl4), to form the conductive material may result in damage to underlying materials upon which the conductive material is formed. The halogen-containing metal precursor reacts with the underlying material, such as a high-k dielectric material, causing an interface between the conductive material and the underlying material to be damaged before the conductive material coalesces. For example, when forming a titanium nitride (TiN) material using TiCl4 over a high-k dielectric material, the TiCl4 may react with the high-k dielectric material and form a discontinuous (e.g., non-uniform) titanium oxide and titanium suboxide material between the high-k dielectric material and the TiN material. This discontinuous titanium oxide and titanium suboxide may cause increased leakage current through the dielectric material and may introduce localized micro roughness and state density at the interface between the conductive material and the underlying high-k dielectric material, leading to lower capacitance of a semiconductor device that includes the high-k dielectric material.
Despite these disadvantages, some of these halogen-containing metal precursors exhibit beneficial properties, such as high capacitance of the resulting stack structure. Various solutions have been attempted to overcome these problems including increasing the thickness of the underlying materials to effectively block leakage current, forming the conductive materials with organic precursors, or forming the conductive material at lower process temperatures. However, each of these solutions creates problems such as increased equivalent oxide thickness or a decrease in overall capacitance of the stack structure.
It would be desirable to form a conductive material to increase the overall device capacitance without damaging or etching underlying material or materials. It would also be desirable to form the conductive material using a halogen-containing metal precursor.

Interfacial materials for use in semiconductor structures and related methods


A recombinant DNA molecule adapted for transfection of a host cell comprising a nucleic acid molecule encoding mammalian erythropoietin, an expression control sequence operatively linked thereto and at least one SAR element. The invention also relates to expression vectors having the recombinant DNA molecule and to mammalian cells transformed with the expression vector. The mammalian cells lack multiple copies of an amplified amplification gene and are capable of expressing recombinant EPO in vitro at levels of at least 1,500 u/10.sup.6 cells in 24 hours. The invention further relates to a method of expressing recombinant mammalian erythropoietin using the expression vectors and to a transgenic non-human animal or embryo whose germ cells and somatic cells contain a DNA construct having the recombinant DNA molecule of the invention.

Erythropoietin (EPO) is a heavily glycosylated acidic glycoprotein with a molecular weight of approximately 35,000. The protein consists of 166 amino acids and has a leader signal sequence of 27 amino acids which is removed in vivo during secretion from the host cell. The sequence encoding the unprocessed EPO is 579 nucleotides in length (Jacobs et al, 1985, Lin et al, 1985, U.S. Pat. No. 4,703,008 and WO 86/03520).
Erythropoietin is the principal hormone involved in the regulation and maintenance of physiological levels of erythrocytes in mammalian circulation and functions to promote erythroid development, to initiate hemoglobin synthesis and to stimulate proliferation of immature erythroid precursors. The hormone is produced primarily by the adult kidney and foetal liver and is maintained in the circulation at concentrations of about 10-20 milliunits/ml of serum under normal physiological conditions. Elevated levels of EPO, induced by tissue hypoxia, trigger proliferation and differentiation of a population of receptive progenitor stem cells in the bone marrow, stimulating hemoglobin synthesis in maturing erythroid cells and accelerating the release of erythrocytes from the marrow into the circulation.
Recombinant EPO has been used to successfully treat patients, including patients having anemia as a result of chronic renal failure. As EPO is the primary regulator of red blood cell formation, it has applications in both the diagnosis and treatment of disorders of red blood cell production and has potential applications for treating a range of conditions.
The urine of severely anaemic patients was, at one time, almost the sole source for the commercial isolation of EPO. U.S. Pat. No. 3,033,753 describes a method for obtaining a crude EPO preparation from sheep plasma. The preparation of monoclonal antibodies specific for human EPO provided a means for identifying EPO produced from EPO mRNA, for screening libraries and for cloning the EPO gene. Human EPO cDNA has been cloned and expressed in E. coli (Lee-Huang, 1984, Proc. Natl. Acad. Sci. 81:2708). Isolation of the human EPO gene using mixtures of short or long synthetic nucleotides as probes led to the expression of biologically active EPO in mammalian cells (Lin, 1985, Proc. Natl. Acad. Sci. 82:7580; Lin, WO 85/02610; Jacobs, et al., 1985, Nature (Lond.) 313:806; Goto et al., 1988, Biotechnology 6:67). Jacobs, et al., 1985, supra, described the use of plasmids containing EPO DNA which were not integrated into the chromosomes of the COS host cells, but replicated autonomously in the cells to many thousands of copies, thereby killing the cells. Thus the expression of EPO was only a transient phenomenon in these cells.
Lin, in U.S. Pat. No. 4,703,008, reported expression of the human EPO gene in COS-1 and CHO cells. However, attempts to use transfected cells as production vehicles for EPO have been hampered by the low levels of EPO expressed by transfected cells. Given the important applications of recombinant EPO, there is much interest in developing more efficient methods for the expression of EPO.
Lin in U.S. Pat. No. 4,703,008 reported methods to increase the low amounts of EPO produced by transfected CHO cells (e.g. 2.99 u/ml/3 days) by a process of gene amplification. Levels of approximately 1500 units EPO/10.sup.6 cells/48 hours were reported by Lin, following amplification. Gene amplification involves culturing cells in appropriate media conditions to select cells resistant to a selective agent, such as the drug methotrexate. Selection for cells resistant to methotrexate produces cells containing greater numbers of DHFR genes and passenger genes, such as the EPO gene carried on the expression vector along with the DHFR gene or transfected with the DHFR gene.
However, gene amplification is a very time consuming and labour intensive process. A major disadvantage of amplification is the inherent instability of amplified genes (McDonald, 1990, Crit. Rev. Biotech. 10:155). As it is usually necessary to maintain the amplified cells in the presence of toxic analogs to maintain high copy number, amplification may be inappropriate for large scale production due to the costs and toxicity of the selective agent. The high copy number of the DHFR-target transgene may also sequestor transcription factor, leading to a retardation of cell growth.
Genomic clones of human EPO have been used in attempts to develop stably transfected mammalian cell lines that secrete high levels of active erythropoietin (Powell, et al., 1986, Proc. Natl. Acad. Sci. 83:6465; Masatsuga, et al., European Patent Application Publication No. 0 236 059). In PCT Application WO 88/00241 Powell, describes the preparation of mammalian cell lines (COS-7 and BHK) transfected with the Apa I restriction fragment of the human EPO gene and selected for high expression by amplification.
Human EPO cDNA has also been expressed in mammalian cells (Yanagi, et al., 1989, DNA 8:419). Berstein, in PCT application WO 86/03520 describes the expression of EPO cDNA in various host cells, resulting in the secretion of up to 160 ng/ml of EPO into the medium after amplification. European Patent Application publication No. 0 267 678 discloses expression of recombinant EPO and secretion into the culture medium at levels of 600 units/ml.
A few scaffold attachment region (SAR) elements have been shown to increase the expression of reporter genes in transfected cells. SAR elements are thought to be DNA sequences which mediate attachment of chromatin loops to the nuclear matrix or scaffold. SAR elements are also known as MAR (matrix-associated regions) (reviewed by Phi-Van and Stratling, Prog. Mol. Subcell. Biol. 11:1-11, 1990). These elements will hereinafter be referred to as "SAR elements". SAR elements are usually 300 or more base pairs long, and they require a redundancy of sequence information and contain multiple sites of protein-DNA interaction. SAR elements are found in non-coding regions: in flanking regions or introns.
Stief, et al., (Nature 341:343-345, 1989) stably transfected chicken macrophage cells by constructs which contained the CAT gene either fused to the lysozyme promoter, or to the lysozyme promoter and the lysozyme enhancer. When the transcription units contained in both constructs were flanked on both sides by lysozyme 5' SAR elements (A elements), gene expression was increased about 10 times relative to transfectants, which contained the constructs lacking the SAR elements.
Phi-Van, et al., (Mol. Cell. Biol., 10:2302-2307, 1990) determined the influence of the SAR element located 5' to the chicken lysozyme gene (A element) on the CAT gene expression from a heterologous promoter (herpes simplex virus thymidine kinase promoter) in stably transfected heterologous cells (rat fibroblasts). The median CAT activity per copy number in transfectants was 10 times higher for the transcriptional unit flanked on both sides by A elements than for the transcriptional unit lacking SAR elements.
Klehr, et al., (Biochemistry, 30:1264-1270, 1991) stably transfected mouse L cells by different constructs containing the human interferon .beta. gene. When the construct was flanked by SAR elements, the gene transcription level was enhanced 20-30 fold with respect to the SAR-free construct, containing only the immediate regulatory elements.
However, the above-noted experiments have been limited to a very few examples of SAR elements, expressing mostly reporter genes, such as chloramphenicol acetyl transferase (CAT) or luciferase. SAR elements have not shown consistent results in their effect on the expression of target genes and some target gene sequences have been found to inhibit the effect of SAR elements (Klehr, et al., 1991, Biochemistry 30:1264).

Recombinant DNA molecules and expression vectors for erythropoietin


A radio-frequency receiver employing antenna diversity is provided with a plurality of antennas and a local oscillator. Individual error signals are derived from each of respective ones of signals received from the plurality of antennas. The error signals are thereafter combined in such a way as to arrive at a combined error signal having greater reliability than any one of the individual error signals taken alone. Finally, an automatic frequency control circuit is controlled using the combined error signal. Since the effect of fading on the input signal to the automatic frequency control circuit is reduced, performance of the automatic frequency control circuit is increased and the quality of radio reception is improved.

The present invention relates to radio receivers and more particularly to automatic frequency control in diversity radio receivers.
Automatic frequency control is commonly used in radio receivers to, insofar as possible, keep the radio receiver locked on a frequency desired to be received despite imperfect component stability that would otherwise result in frequency drift. In one known arrangement, for example, a received carrier frequency is mixed with a local replica of the carrier frequency produced by a local oscillator to yield a baseband signal. The frequency error of the baseband signal is measured and the error signal is used to adjust the frequency in the local oscillator to more closely coincide with the actual carrier frequency, resulting in better reception.
Since radio communications exhibit a well-known fading channel characteristic, when fading is severe, it becomes difficult to obtain a reliable error signal in order to adjust the frequency of the local oscillator using an automatic frequency control circuit. Perversely, effective automatic frequency control is most needed during such fading in order to improve reception quality.
Space diversity whereby reception is effected using a plurality of spaced-apart antennas is known to reduce the effects of fading. No application has been made, however, of space diversity to automatic frequency control.
What is needed then, is an automatic frequency control arrangement that is more effective in the presence of fading.

Diversity radio receiver automatic frequency control


A configuration management system tracks the configuration of a computing environment based on a tracking policy. The configuration management system detects a change to a configuration setting included in the tracking policy, and classifies the change. The classification is indicative of an effect of the change on an ability to manage operation of the computing environment. The configuration management system initiates an action, based at least in part on the classification, in response to the change.

The operation of a computing system is typically influenced by various configuration settings. A diverse selection of such settings is typically available. Examples include, but are not limited to, settings related to security, performance tuning, application options, and so on. The management of such settings is often a complex task, particularly where two or more parties may independently make changes to the same system.


A location detection system identifies the locations of medical devices such as patient support apparatuses and/or patient care devices within a medical facility. The devices communicate via a wired connection to one or more medical facility systems (e.g. nurse call system, computer network, etc.), and/or via a wireless connection to such systems. The location detection system automatically determines location information of the devices and communicates the location information so that the recipient of any outgoing alerts and/or other information sent from the devices is apprised of the location of the particular device sending the alert or other information. Caregivers are thereby able to respond to the correct location of an alert, and software systems such as EMR systems, admission discharge and transfer (ADT) systems, etc. are able to correlate transmitted device data with the location and/or patient assigned to that location.

The present disclosure relates to patient support apparatuses (e.g. beds, stretchers, cots, recliners, etc.), and patient care devices, and more particularly to systems and methods for determining and communicating the location of the patient support apparatuses and/or patient care devices within medical facilities.
Patient support apparatuses and patient care devices used in medical facilities often are designed to include one or more alerts states and/or to generate data that is desirably communicated to another location within the healthcare facility (e.g. a nurses' station, an electronic medical records (EMR) server, to mobile devices carried by individuals, etc.). In order for the alerts and/or data to be meaningful to the recipient, it is typically desirable to identify the room number or other location identifier that indicates where the patient support apparatus or patient care device is currently positioned.

This patent is subject to a terminal disclaimer.


A method for fabricating a thin-film magnetic head comprises the steps of providing an alignment marker used for alignment in patterning processes on an insulating layer, depositing a conductor base layer on the insulating layer to bury the alignment marker underneath, growing a pattern on the conductor base layer by an electro-plating process while using said conductor base layer as an electrode, removing the conductor base layer except for a part thereof located under the pattern by a chemical etching process that acts selectively upon the conductor base layer while leaving the alignment marker and the insulating layer substantially unetched.

The present invention generally relates to magnetic storage devices generally called "hard disk," and more particularly to a fabrication process of a thin film head used in such a magnetic storage device.
In computer systems, various magnetic storage devices are used. Among others, the device called "hard disk" is used extensively as a large capacity auxiliary storage device that cooperates with a high speed semiconductor memory device forming a main memory of a central processing unit.
In the hard disk devices, one or more rigid magnetic disks revolving about a common rotational axis at a high speed are provided, and a magnetic coating is provided on the upper and lower major surfaces of each magnetic disk. Typically, the magnetic disk is defined with a number of concentric tracks on the magnetic coating, and a magnetic head carried on a tip end of a swing arm scans the surface of the magnetic disk generally in the radial direction thereof as a result of the swinging motion of the arm.
Generally, the magnetic disk is revolved at a speed in the order of several thousand r.p.m. and the magnetic head that scans the surface of the magnetic disk establishes a magnetic engagement with the disk while being separated therefrom by a thin air foil.
FIG. 1 shows a typical hard disk device in the plan view, wherein it will be noted that there is provided a magnetic disk 1 revolving about an axle 1a by a driving motor not illustrated in FIG. 1. At the outer periphery of the disk 1, there is provided a swing arm 3 such that the arm 3 is rotatable about an axle 4, and the arm 3 carries a magnetic head 2 on the free, tip end thereof. There, the arm 3 is driven by a voice coil motor 5 and swings about the axle 4, and the magnetic head 2 scans the surface of the disk 1 in the radial direction thereof with the swinging motion of the arm 3. Further, the magnetic head 2 is connected electrically to an electronic circuitry schematically illustrated by a numeral 6 by a flexible cord (FPC) 7. There, an interconnection wire 7a extending along the side wall of the arm 3 connects the magnetic head 2 and the flexible cord 7.
The structure shown in FIG. 1 is stacked by a number of layers as shown in FIG. 2, wherein it will be noted that there are a number of magnetic disks 1 stacked each other, and a number of swing arms 3 as well as a number of magnetic heads 2 are provided in correspondence to the plurality of magnetic disks 1. It should be noted that the swing arms 3 and the magnetic heads 2 are provided respectively in correspondence to the upper and lower major surfaces of each magnetic disk 1. Thereby, the swing arms 3 form an arm assembly 4A. Further, the entire structure of the hard disk device is accommodated in a hermetically sealed enclosure 10 (FIG. 1).
FIG. 3 shows the magnetic head 2 in a perspective view.
Referring to FIG. 3, the magnetic head 2 includes a head body 2a that is formed with a pair of elongated air bearing surfaces 2b. The air bearing surfaces 2b face the upper or lower major surface of the magnetic disk 1 and forms an air foil therebetween. Further, each air bearing surface 2b includes an oblique guide surface part 2c at the longitudinal end thereof corresponding to the upstream side of the relative motion of the disk 1 to the head 2, for introducing the air into a gap formed between the air bearing surface 2b and the corresponding major surface of the magnetic disk 1. Further, at an end surface 2d corresponding to the downstream end of the relative motion of the disk 1, there is provided a thin-film head 2e of which construction is shown in detail in FIG. 4.
Referring to FIG. 4, the thin-film head 2e includes a winding pattern 2u and a pair of thin-film magnetic yokes 2v and 2w provided on the end surface 2d of the head body 2, wherein the magnetic yoke 2w is formed underneath the winding pattern 2u while the magnetic yoke 2v is formed above the winding 2u. The magnetic yokes 2v and 2w extend toward the air bearing surface 2b and forms a gap 2x for creating a magnetic flux penetrating into the magnetic layer that is coated on the surface of the disk 1. Further, it will be noted that bonding pads 2y and 2z are provided on the end surface 2d for external electrical connection.
FIG. 5 shows the structure of the thin-film head 2e in vertical cross section, wherein the upper diagram in FIG. 5 shows the gap part of the head in an enlarged scale.
Referring to FIG. 5, it will be noted that the winding pattern 2u is provided in the space formed between the upper yoke 2v and the lower yoke 2w in two layers, wherein the space is filled by an insulating material. The lower yoke 2w is provided on the surface 2d of the head body 2, wherein the upper and lower yokes 2v and 2w approach with each other at the gap portion 2g, leaving a minute gap corresponding to the gap 2x therebetween as represented in the upper diagram of FIG. 5. There, the disk 1 moves along the air bearing surface 2b in the direction indicated by an arrow in FIG. 5, and the gap part 2g is formed substantially flush to the air bearing surface 2b. Thereby, the magnetic flux exiting from the yoke 2v and returning to the yoke 2w or vice versa crosses the magnetic coating on the disk 1 and causes a horizontal recording of information in the magnetic coating of the rigid magnetic disk 1 as usual.
Next, the conventional process for fabricating such a thin-film head 2e will be described with reference to FIGS. 6(A)-6(G).
Referring to FIG. 6(A) first, an insulation layer 12 of Al.sub.2 O.sub.3 is provided on an upper major surface corresponding to the surface 2d of a substrate 11 that forms the head body 2. Typically, Al.sub.2 O.sub.3.TiC is used for the substrate 11. Further, on the upper major surface of the insulation layer 12, a permalloy (Fe/Ni alloy) layer 13 forming the lower yoke 2w is deposited by an electro-plating process. The permalloy layer 13 is patterned to form a generally triangular lower yoke 2w. Typically a deposition rate of 1500-2000 .ANG./min is employed for the formation of the layer 13.
Next, in the step of FIG. 6(B), a gap layer 14 of Al.sub.2 O.sub.3 is deposited in correspondence to the gap to be formed between the lower yoke 2w and the upper yoke 2v, and an insulation layer 15 is deposited further thereon in a step of FIG. 6(C) except for the part where the gap region 2g is to be formed. The insulation layer 15 may be a photoresist that is baked after patterning to form a mechanically rigid and chemically stable insulator.
Next, in a step of FIG. 6(D), a spiral-shaped resist pattern is formed on the layer 15 and a conductor layer such as copper is deposited on the patterned surface of the insulator layer 15 by an electro-plating process. Typically, a deposition rate of about 1000-1300 .ANG./min is used, and a winding pattern 16 corresponding to the winding pattern 2u of FIG. 4 is obtained after removal of the spiral-shaped resist pattern. Further, the remaining copper layer is removed by a wet etching process that is typically conducted at a temperature of about 15.degree.-17.degree. C. in an etchant solution of ammonium persulfate, while protecting the winding pattern 16 by a photoresist.
Next, in a step of FIG. 6(E), an insulation layer 17 is deposited to bury the winding pattern 16 underneath. Typically, a photoresist is used for the layer 17. There, the photoresist is deposited and patterned photolithographically to form a layer corresponding to the layer 17, and the layer thus formed is subjected to a baking process to convert the photoresist to a stable insulation layer 17.
Next, in a step of FIG. 6(F), another permalloy layer 18 corresponding to the upper yoke 2v is deposited on the structure of FIG. 6(E) by an electro-plating process and patterned subsequently in accordance with the generally triangular shape of the upper yoke 2v. Further, in a subsequent step of FIG. 6(G), an upper protective layer 19 of Al.sub.2 O.sub.3 is deposited on the layer 18, and the structure thus obtained is subjected to a grinding and finishing process starting from the left side in FIG. 6(G) to form the thin-film head structure shown in FIG. 5.
In the foregoing steps such as the step of FIG. 6(A), one encounters a problem of depositing the permalloy layer 13 on the insulating layer 12 by means of the electro-plating process. A similar problem occurs also in the step of FIG. 6(D) for depositing a copper layer on the baked photoresist layer 15 or in the step of FIG. 6(F) for depositing the upper permalloy layer. In order to enable the electro-plating on the insulator layer, the use of a conductive base layer has been employed conventionally as shown in FIGS. 7(A)-7(E), wherein these drawings correspond to the step of FIG. 6(A) for forming the lower magnetic yoke 2w. It should be noted that the upper drawings in FIGS. 7(A)-7(E) represent the plan view while the lower drawings represent the corresponding cross-sectional view.
Referring to FIG. 7(A), a conductive base layer 21 is deposited on the upper major surface of the insulation layer 12 by evaporation or sputtering. The base layer 21 has a composition substantially identical with the permalloy layer to be grown thereon. Further, a photoresist is deposited on the layer 21 and patterned subsequently in accordance with the outer boundary of the lower magnetic yoke 2w to be formed. Thereby, the patterned resist 22 circles the region on which the magnetic yoke 2w is to be formed.
Next, in the step of FIG. 7(B), the permalloy layer 13 is deposited on the base layer 21 by the electro-plating process while using the base layer 21 as an electrode. Thereby, the permalloy layer 13 covers the surface of the layer 21 except for the part covered by the patterned resist 22.
Next, in the step of FIG. 7(C), the photoresist 22 is removed to form a groove 22' in correspondence to where the patterned resist 22 has been provided, and the entire structure is subjected to an ion milling process such that the base layer 21 is removed entirely from the groove 22'. Further, a resist 23 is deposited and patterned subsequently to cover selectively the patterned layer 13 corresponding to the lower magnetic yoke 2w in a step of FIG. 7(D), and the remaining permalloy layer 13 is removed in a step of FIG. 7(E) by a wet etching process while protecting the lower magnetic yoke 2w by a resist 23. Further, in the step of FIG. 7(E), the conductive base layer 21 that is exposed as a result of the wet etching of the layer 13 is removed by an ion milling process or sputter etching process. Typically, the wet etching process of permalloy is conducted at a temperature of 22.degree.-24.degree. C. by an etchant that includes purified water, sulfuric acid and hydrogen peroxide with a volume ratio of 1000 ml:340 ml:180 ml. It should be noted that a similar conductive base layer used when providing the copper winding pattern 16 on the insulator layer 15 as shown in FIG. 6(D) and also in the step of FIG. 6(F) wherein the upper magnetic yoke 18 is provided on the insulation layer 17 by the electro-plating process.
In the foregoing step of FIG. 7(C), the ion milling process is applied to remove the conductive base 21 in correspondence to the groove 22' such that the conductor base 21 is completely removed in correspondence to the groove 22' such that the exposed surface of the layer 21 is covered directly by the photoresist 23 in the step of FIG. 7(D). Thereby, one can prevent the wet etching conducted in the step of FIG. 7(E) from penetrating laterally into the region located under the lower magnetic yoke 13 along the exposed conductor layer 21.
On the other hand, the ion milling process in the step of FIG. 7(E) is conducted to remove the conductor layer 21 completely for eliminating the problem of short circuit. In order to assure that no conductor layer 21 remains on the exposed surface, the ion milling process of FIG. 7(E) is conducted to penetrate relatively deeply. It should be noted that the deviation in the compositional uniformity or layer thickness in the layer 21 tends to cause a variation in the ion milling rate, and there is a substantial risk that a part of the conductive base layer 21 remains unremoved, particularly in view of the large area that is subjected to the ion milling process. The same problem occurs when a sputter etching process is employed in place of the ion milling process. In addition, such a physical etching process applied to a large depth causes various problems such as long processing time that decreases the throughput of production. Hereinafter, the problem associated with the physical etching process employed in the step of FIG. 7(E) will be examined briefly with reference to FIG. 8.
FIG. 8 shows the physical etching process conducted in the step of FIG. 7(E), wherein the solid line and the broken line represent respectively the state before and after the physical etching. There, it will be noted that the part of the layer 12 at both sides of the pattern 13 is grooved deeply as represented by the numerals 13a and 13b because of the concentrated bombardment of atoms such as Ar that is used for ion milling or sputter etching. When there exists such a deep groove on the surface of the layer 12, various problems such as disconnection of the interconnection may occur. Further, the depth of the etching tends to differ location to location even in the marginal region that surrounds the pattern 13, and the fabrication of thin-film heads based upon such an unreliable and unpredictable process is extremely difficult particularly in the cases where a very high precision is required for the magnetic heads.
Another and probably more serious problem associated with the use of the physical etching of the layer 21 would be that the alignment marker such as a pattern 24, which is provided on the surface of the layer 12 for the sake of the positional reference for various patterning processes, may be worn out as a result of the abrasive action of the physical etching. When the marker pattern 24 becomes obscured, the subsequent patterning process such as the formation of the winding pattern 16 becomes extremely difficult. Thereby, the throughput of the device production as well as the yield of the product are inevitably deteriorated. It should be noted that the alignment marker 24 is formed of a metal having a high reflectance such as Ti and may have a thickness of 1000 -2000 .ANG., for example. When the alignment marker 24 is obscured as such, not only the patterning of the lower magnetic yoke 2w but also the formation of the winding pattern 16 as well as the upper magnetic yoke 2v becomes difficult.

Thin film head for a magnetic storage device