Non-noble metal transition metal catalysts can replace platinum in the oxidation reduction reaction (ORR) used in electrochemical fuel cells. A RuxSe catalyst is prepared with comparable catalytic activity to platinum. An environmentally friendly aqueous synthetic pathway to this catalyst is also presented. Using the same aqueous methodology, ORR catalysts can be prepared where Ru is replaced by Mo, Fe, Co, Cr, Ni and/or W. Similarly Se can be replaced by S.

1. Field of the Invention
The field of the invention relates to non-noble metal catalysts for the oxygen reduction reaction including methods of manufacture.
2. Description of the Related Art
Electrochemical fuel cells convert fuel and oxidant to electricity and reaction product. Solid polymer electrochemical fuel cells generally employ a membrane electrode assembly ("MEA") in which an electrolyte in the form of an ion-exchange membrane is disposed between two electrode layers. The electrode layers are made from porous, electrically conductive sheet material, such as carbon fiber paper or carbon cloth. In a typical MEA, the electrode layers provide structural support to the membrane, which is typically thin and flexible.
The MEA contains an electrocatalyst, typically comprising finely comminuted platinum particles disposed in a layer at each membrane/electrode layer interface, to induce the desired electrochemical reaction. The electrodes are electrically coupled to provide a path for conducting electrons between the electrodes through an external load.
A significant emphasis has been placed to reduce MEA costs by reducing the platinum loading while maintaining or even improving performance and reliability. One approach is to eliminate platinum entirely and replace it with a cheaper alternative catalytic material. In particular, a significant amount of work has been done working on replacing platinum for the oxygen reduction reaction at the cathode.
Aside from cost, platinum catalysts have a further disadvantage when used in direct methanol fuel cells (DMFCs) in which methanol is used as the fuel. Namely, platinum at the cathode oxidizes methanol that crosses over from the anode leading to depolarisation and hence serious power losses in the cell.
Bron et al. (Journal of Electroanalytical Chemistry 500, 2001, 510–517) discloses a ruthenium-based catalyst for oxygen reduction. The catalysts were prepared by reacting Ru3(CO)12 with selenium for 20 hours in deaerated xylene under reluxing conditions. The product was filtered, washed with diethylether and dried in an oven at 90° C. to produce a black powder. Bron et al. studied the effect of selenium and found a maximum benefit at about 15 mol % Se though catalytic activity was still observed in a selenium free catalyst. Bron concluded that the catalytic center in the selenium-containing catalyst is different from the catalytic center in the selenium-free catalyst. Selenium was also found to protect the catalyst against electrochemical oxidation and therefore led to enhanced stability.
In a second publication produced by the same group, Tributsch et al. (Journal of Applied Electrochemistry 31, 2001, 739–748), found that heating of this product resulted in the loss of carbon species in well defined steps. The first step involved the loss of CO and CO2 between 250 and 350° C. and a second step was observed at temperatures above 600° C. Further, Tributsch et al. found a loss of catalytic activity resulting from the release of carbon species at elevated temperatures. This led Tributsch et al. to propose a complicated catalytic structure comprising a cubane-like organometallic ruthenium-complex on the surface of a ruthenium nanoparticle doped with a chalcogen (selenium or sulfur). Inspiration for this model appears to be an iron hydrogenase from the Clostridium pasteurianum bacterium.
In a prior study on a related system, namely a MoRuS and MoRuSe system, Trapp et al. (J. Chem. Soc, Faraday Trans. 92(21), 1996, 4311–4319) arrived at significantly different conclusions. In the synthesis carried out by Trapp et al., Ru3(CO)12 and Mo(CO)6 were refluxed in xylene with sulfur or selenium for 20 hours. The catalyst powder was then filtered and dried at room temperature before being introduced into a tubular furnace at 350° C. for one hour. Though Trapp et al. also performed a heating step, instead of reduced catalytic activity as reported by Tributsch et al. supra, Trapp et al. observed improved activity. In fact, such heating step was referred to as "catalyst activation." In addition, Trapp et al. concluded that the Ru species is the active center of the catalyst with some synergistic effects observed between the ruthenium and the molybdenum sites in the mass-transport region. Trapp et al. also found that catalytic activity of the MoRuS was not affected by methanol. Under conditions of simulated methanol cross-over, the activated MoRuS catalyst had a similar activity to platinum. However, similar activity was only observed with methanol present. In the absence of methanol, the activity of activated MoRuS catalyst was significantly worse than platinum.
Despite considerable efforts, a non-noble metal-based catalyst with activity similar to platinum has yet to be developed. In addition, existing synthetic methodologies are directed to experimental scale and, as such, are not necessarily amenable to commercial scale production. For example, metal carbonyls, which are typically used as starting materials, are relatively expensive and typical solvent systems used, namely xylene, are toxic and environmentally damaging. Thus, even if the catalysts were suitable for use in fuel cells, an environmentally friendly synthetic method would be needed.
The present invention fulfills these and other needs and provides further related advantages.

Non-noble metal catalysts for the oxygen reduction reaction


A method and apparatus are described for selecting an access point in a wireless network, including initializing a channel index, recording a received signal power and information contained in one of a beacon message and a probe request response message, calculating an access link metric for each candidate access point, the access link 13  metric being between an end device and each candidate access point on the channel indexed by the channel index responsive to the received signal power and information receiving a path metric between each candidate access point and a gateway, estimating a function using the access link metric and the path metric, selecting one of the candidate access points based on the function and establishing a connection with the selected access point. Also described is a method and apparatus for maintaining a connection with an access point.

Several methods have been proposed in the literature to select an access point (AP) in single-hop wireless networks. The conventional approach for AP selection is based on received signal strength indicator (RSSI), in which an end device associates with/connects to an AP having the strongest received signal strength. This policy, however, ignores other factors that are important to end devices (such as AP load). Such factors could lead to very bad performance. In one prior art, the number of associated/connected end devices is used as a metric to select an AP. However, this metric does not consider the access link quality between the end devices and AP. In another prior art method, an AP selection metric based on the total number of users/end devices associated with/connected to the AP and the average packet error rate of a user/end device is used to select an AP. However, the model used in this metric does not capture the bandwidth contention among the end devices and different link data rates of the end devices. In yet another prior art method, a centralized method for determining an end device/user-AP association/connection is used to ensure a network-wide max-min fair bandwidth allocation to users/end devices. However, this method requires a central controller that knows the bandwidth of each end device.
All of the above approaches were designed for single-hop wireless networks; where end devices are only one hop away from the wired backbone and the wireless access link is assumed to be the bottleneck. All the above methods do not jointly consider the impact of the access link quality and the quality change of the path inside the network to the communication performance of the end device's.
In a multi-hop wireless network, the communication performance of end devices (e.g., fairness, throughput) is not only affected by the access link but also by the connection between the AP/relay node (RN) and the gateway (GW)/base station (BS). Therefore, when the problem of AP/RN selection in multi-hop wireless networks is considered, the schemes for single-hop wireless network cannot be used. A new AP selection method that considers both the access link and the path quality inside the network needs to be developed.
A solution to the problem of how to select an AP/RN in multi-hop wireless networks by considering both the path metric inside the network and the access link quality from the end device to the AP would be advantageous.

Method to select access point and relay node in multi-hop wireless networking


A helical antenna having stubs spaced along the helix curve length and extending toward the central axis of the helix, such that the performance characteristics of the antenna, such as gain and circular polarization, are maintained while the size of the antenna--diameter and length--are reduced.

1. Field of the Invention
The present invention generally relates to helical antennas, and more particularly to helical antenna geometries which support reduced antenna size.
2. Background Description
The helical antenna is old in the art, having first appeared in the late 1940's. In a helical configuration, a length of conducting material is wound at a radius and with a pitch angle around a central axis. The radius of curvature of the helix is defined by the radius of the enclosing cylinder. The helix antenna produces a directional antenna pattern, generates circularly polarized radio waves, and has a wide operational frequency bandwidth.
In certain communication applications the antenna may be the largest component of the system. Thus there is a need for a way to reduce antenna size without reducing antenna performance.

Virginia Tech Intellectual Properties, Inc.


A semiconductor memory apparatus according to the present invention consists of memory cell forming regions, each formed in a rectangular plane form, a plurality of bit line pairs connected to a plurality of memory cells arranged and formed in these memory cell forming regions, and first and second peripheral circuits formed outside said memory cell forming regions, wherein said first and second peripheral circuits are formed and arranged symmetrically with respect to the point of intersection of two centerlines connecting the middle points of two opposite ones of the four sides of each of said memory cell forming regions, and said bit line pairs are connected to the first and second peripheral circuits. This configuration makes it possible to match the constituent elements of the peripheral circuits with each other and balance the bit line pairs, and thereby to prevent the drop in writing or reading rate and erroneous operations, to which semiconductor memory apparatuses according to the prior art are susceptible.

1. Field of the Invention
The present invention relates to a semiconductor apparatus, and more particularly to the arrangement of circuits peripheral to a dynamic random access memory (DRAM).
2. Description of the Prior Art
Usually a semiconductor memory apparatus, such as a DRAM, consists of memory cell array forming sections, formed by arranging memory cells, and peripheral circuits adjacent to it, including sense amplifiers, row decoders and column decoders. Among these peripheral circuits, specific items such as sense amplifiers, one of which is provided for each pair of bit lines to each of which is supplied to a voltage in a complementary relationship to each one of a plurality of bit lines constituting the memory cell array, have to be installed at a rate of one unit per pair of bit lines. Therefore, these specific peripheral circuits are arranged along a side of said memory cell array forming sections.
In recent years, microprocessing techniques for semiconductors have made remarkable progress, resulting in a reduction in the area in which each bit of said memory cell is formed on a single semiconductor chip with a corresponding reduction in the pitch of the repetitive arrangement of each of bit line pairs connected to a plurality of said memory cells on said semiconductor chip.
Meanwhile, so-called specialized semiconductor memories embodying the application to functions unique to a particular system, typically including picture memories, have become commercially available and are extensively used. In such a specialized semiconductor memory, peripheral circuits for such system functions as serial data transfer and flash clear should be provided for each pair of said bit lines in order to realize these functions on said semiconductor chip. Thus, peripheral circuits used for said specialized semiconductor memory include line buffer circuits and serial switching circuits in addition to said sense amplifiers, resulting in a complex and large-scale configuration. Accordingly, it has become difficult to arrange these peripheral circuits along a side of said memory cell array forming sections at the repetitive pitch of said bit line pairs. Should said peripheral circuits be arranged in disregard of said repetitive pitch, the characteristics of transistors, which are the constituent elements of the peripheral circuits, would become unmatched, and moreover said bit line pairs would be laid in an elongated state, resulting in large resistances and capacities added to the bit line pairs.
This would have the consequence, as voltage variations on the bit line pairs are delayed when signals are read or written, of not only significantly slowing down the reading and writing rates of the semiconductor memory apparatus but also inviting erroneous operations.


Gravity information for a gravity survey is obtained by using an array of relative gravimeters whose relative gravity measurement signals have been calibrated by using an absolute gravimeter to approximate absolute gravity measurements. The absolute gravimeter is moved periodically to the location of each relative gravimeter to measure absolute gravity. The absolute and relative gravity measurements for each relative gravimeter form an error signal which is used to calibrate each relative gravimeter.

The gravitational force of attraction between two massive bodies is the force which results from the inherent natural attraction between the two bodies. The magnitude of the gravitational force is related to the mass of the bodies and is inversely related to the separation distance between centers of mass of the bodies. Gravity is measured as acceleration. For instance, and in general, 9.8 m/s2 is the acceleration that a 1 gram massive object will fall toward the ground when it is thrown from the roof of a building.
A gravimeter is an instrument used to measure the strength or magnitude of gravity. Gravimeters are well known and typically measure the vertical component of the total gravity vector of the earth in units of acceleration. The common unit of measurement of gravity is the "gal," which is a unit of acceleration defined as 1 gal=1 cm/s2=0.01 m/s2=10−3 g. The typical gravimeter currently measures gravity to the nearest microgal (1 μgal=10−9 g). These types of measurements are referred to herein simply as "gravity measurements."
Gravity measurements are useful for a number of different purposes, as illustrated by the following examples. Gravity measurements are used to monitor subsurface density changes resulting from immediate to long-term subterranean events. Gravity measurements are also used to monitor the influx of water when flooding a petroleum reservoir to push hydrocarbon into extraction wells. The confinement of waste gas and liquid substances stored in subsurface caverns or containments are monitored by gravity measurements to detect whether the waste and liquid substances remain securely confined. Water management techniques make use of gravity measurements to monitor the extent to which groundwater moves or the extent to which rainwater penetrates into and saturates the soil.
In all of these uses, changes in the quantity of the substance, such as the oil, water or gas, alter the density of the volume of material at the monitored location. That change in mass, through Newton's law, changes the gravity around and above that specific monitored location. For example, in the absence of any other change, the depletion of petroleum from a subterranean reservoir decreases gravity at the point above the reservoir due to the reduction of petroleum in the reservoir. Similarly, the introduction of water to flood a petroleum reservoir increases gravity above those parts of the reservoir where the water has penetrated and replaced a less dense substance or filled a void. The movement of groundwater and waste substances from their previous location is sensed by measuring temporal changes in gravity at specific points surrounding the location. By measuring gravity, the extent of movement of the substance can be determined, and with appropriate accuracy of the measurements, volumetric quantities of the substance can also be determined.
The change in mass of the monitored substance is normally very small compared to the mass of the surrounding earth that defines the reservoir or the cavern or confinement of the substance, so the change in gravity is usually very small. Nevertheless, the change does occur and gravimeters are capable of measuring such relatively small changes in gravity. Gravimeters fall into two categories: a relative gravity measurement instrument known as a relative gravimeter, and an absolute gravity measurement instrument known as an absolute gravimeter. Both types of gravimeters measure the vertical component of the earth's total gravity vector.
A relative gravimeter suspends a mass of known quantity by a spring-like device. An increase in gravity interacts with the known mass in such a way to slightly stretch or elongate the spring-like device. Conversely, a decrease in gravity allows the spring-like device to constrict slightly. In either case, the position of the known mass changes by a slight amount due to the elongation or constriction of the spring-like device. The amount of physical displacement of the known mass is directly related to the magnitude of gravity at that location and time.
An absolute gravimeter is a technically sophisticated, more expensive and physically larger instrument than a relative gravimeter, at the present time. A mass of known quantity is positioned within a chamber which has been evacuated as much as possible to approximate a complete vacuum. A mechanism lifts the known mass and releases it to freefall within the chamber. A laser beam monitors movement of the free falling mass, and an extremely accurate clock measures the time required for the mass to fall a specific distance or measures the speed of the free falling mass at a specific time. By utilizing the distance and/or speed data, the magnitude of gravity acting upon the known mass at the time of the test is calculated.
In a relative gravimeter, the spring-like device which suspends the known mass is susceptible to many influences that degrade the accuracy of the gravity measurements obtained. Changes in temperature of the spring-like device can change its spring characteristics and hence change the displacement of the known mass. Changes in pressure can also change its spring characteristics. Shocks caused by physical movement of the gravimeter can cause an offset or tare in the at-rest position of the known mass. Changes in the spring characteristics of the spring-like device naturally occur over time and are referred to as drift. If these external environmental and characteristic influences and variations are not recognized and corrected, these influences and variations might incorrectly be interpreted as a change in gravity when measuring temporal changes in gravity.
Relative gravimeters are generally less reliable and less accurate than absolute gravimeters for measuring temporal changes in gravity. This is particularly the case when relatively small gravity influences are measured, such as subsurface density changes in subterranean reservoirs. The effect of changes in temperature, pressure, tare or drift can mask any change in the magnitude of gravity, making it impossible to accurately measure small changes in gravity.
While the accuracy of the gravity measurements obtained by using an absolute gravimeter is very high compared to the accuracy in measurements obtained by using a relative gravimeter, the sensitivity and complexity of the absolute gravimeter has made it impossible or very difficult to employ a gravimeter in any location other than in a controlled scientific laboratory where all of the environmental influences can be controlled. Only recently have field-usable absolute gravimeters been developed, but such field-usable absolute gravimeters are expensive, in the neighborhood of US $300,000-500,000, which is roughly five times the price for a relative gravimeter. Furthermore, the use of such field-usable absolute gravimeters is tedious and time-consuming.
The relatively high cost of field-usable absolute gravimeters has had the practical consequence of requiring a single absolute gravimeter to be moved from one location to another, in order to acquire absolute gravity measurements at each of the locations. Even though movable, the sensitivity and fragility of a field-usable absolute gravimeter complicates its use. The set-up time at each location is lengthy, and care must be taken in moving the absolute gravimeter from one location to avoid damage. These factors have the effect of limiting the number of points where gravity can be measured within a specific amount of time. Under typical circumstances, absolute gravity measurements can be made at only two or three different locations in a day. As many as 300 different absolute gravity measurements may be required to complete a gravity survey of a typical petroleum reservoir. Consequently, a relatively long time is required to complete a typical absolute gravity survey.
Each absolute gravity measurement is also time-specific, becoming in effect, a "snapshot" of the gravity that exists at the time when the measurement is made. By the time that an absolute gravity survey of a petroleum reservoir is completed, the measurements can only represent an average of the gravity magnitude over the many days required to complete the survey. Because of the logistical planning and cost involved in conducting an absolute gravity survey, absolute gravity surveys are conducted quite infrequently, typically separated by one year intervals between surveys. The long time between the absolute gravity surveys results in low resolution in the ability to monitor subsurface events over time, even though the gravity measurements are very accurate when made.
Relative gravimeters are more commonly used to conduct gravity surveys. A relative gravimeter is moved from one measurement point to the next measurement point and the change in the gravity between measurement points is recorded. Periodically and before completing all the measurement points, the relative gravimeter is moved back to a reference point, referred to as a base station. The difference in the sequential measurements at the base station is distributed among the measurements collected between the sequential occupations of the base station. This type of gravity survey, where the relative gravimeter is periodically returned to the reference point to derive an error or correction value, is known as "looping." In looping relative gravity surveys, only relative or comparative gravity is measured from one point to the next, including at the base station reference point.
The comparative gravity measurements obtained in a looping relative gravity survey are used as a surrogate for absolute gravity, under the assumption that absolute gravity must be related to the comparative gravity. While there is some validity and utility to this assumption, the accuracy of the gravity measurements made in a looping gravity survey is nevertheless subject to variable influences of temperature, pressure, tare and drift on the relative gravimeter. Moreover, the time and logistics required to accomplish the looping gravity survey can be significant, particularly in rough terrain or in active locations, such as producing oil or gas fields. The added time to perform the looping relative gravity survey also diminishes the ability to monitor dynamic changes in comparative gravity.
There are many desirable reasons for determining subsurface density information on a fairly rapid, dynamic or real-time basis. For example, rapid changes in the gravity field may be indicative of water breakthroughs or leakage of waste substances from their intended locations. Both absolute and relative gravimeters have the capability of responding to more dynamic events, but their acquisition costs, drift characteristics and other factors have limited their practical use for such purposes. Consequently, accurate and dynamic gravity information for gravity surveys has not previously been available on an economic basis.

Accurate dynamic gravity measurement method and apparatus


SC light is generated from the input signal 2, of an OTDM signal light 1 with wavelength λs1 and an input signal 2 with wavelength λs2 using an optical fiber and the like, and the wavelength of the SC light is converted into wavelength λs1 using a BPF with center wavelength λs1 (a specific-timing optical pulse with wavelength λs1 is extracted from the SC light). After the addition timing of the wavelength-converted light is adjusted by a delayer (τ) both this wavelength-converted light and signal light 1 are inputted to an optical add circuit and are added.

1. Field of the Invention
The present invention relates to a device for processing optical signals without converting the optical signals into electrical signals, and in particular, it relates to the improvement of both the flexibility of an optical communications system and the system flexibility at each type of node point of an optical network.
2. Description of the Related Art
To enable high-speed large-capacity communications, at present an optical communications system is being developed and a part of the development is commercialized. Since such an optical communications system handles signals with a bit rate of 10 GHz and more, signals must be processed at speeds corresponding to these bit rates. However, if optical signals are converted into electrical signals, electronic devices cannot operate at a high speed such that optical signals can be handled, which is an obstacle to the implementation of the high-speed large-capacity optical communications described above. Therefore, to implement such high-speed large-capacity optical communications, fully optical devices for processing optical signals without converting the signals into electrical signals must be developed.
For a conventional method for branching/adding optical signals in order to implement the high-speed large-capacity optical communications, a method for processing wavelength-division-multiplexing (WDM) signals in a wavelength domain is generally used. When an optical signal control technology further progresses and each WDM signal channel is composed of high-speed large-capacity signals by optical time-division multiplexing (OTDM), the branching/addition of signals on a time axis will also be needed in the future.
However, the addition/branching of optical signals in OTDM described above requires a very high speed processing. Therefore, if optical signals are branched/added after being converted into electrical signals, the advantage of using optical signals in a sufficiently high-speed and large capacity communications cannot be utilized since the operation of electrical devices are slow.
Therefore, a configuration for enabling the branching/addition of high-speed OTDM signals without converting the signals into electrical signals is needed in the future.


A note acceptor security system includes a currency validator secured to a housing and a note stacker removably received thereby. The currency validator has an identification chip maintained in association therewith and having a fixed serial number. The currency validator also includes a microprocessor which controls the operation of the currency validator and maintains operational data respecting the same. The stacker has a memory chip which is urged into a grounded position which is removed when the stacker is placed into the note acceptor. A fixed probe within the note acceptor lifts the memory chip from ground and allows communication from the microprocessor and identification chip to the memory chip. When the stacker is full, it is removed from the note acceptor and, with the memory chip grounded, it is transported to a docking station where the memory chip is again probed and the data maintained therein is transferred to a personal computer for later use. The memory chip is then erased and the stacker made available for reuse.

The use of note acceptors in association with various vending machines for goods and services is now well known. Specifically, a note acceptor may be associated with a vending machine or gaming machine such that the deposit of currency into the validator results in an authorization for the vending of goods and/or services from the vending machine or gaming machine. Note acceptors must be serviced periodically to retrieve the currency received thereby, and to assure that a full complement of change is available for return to customers.
Typically, service personnel access the note acceptor and retrieve the currency received therein by simply removing the cash box or stacker full of bills and replacing it with an empty one. At the same time, necessary change may be deposited into the note acceptor. The full cash box cassette is then returned to a service area where the money is removed and counted. However, such a process is given to temptation of theft, since inaccuracies in the amount actually received by the note acceptor and that retrieved from the stacker are difficult of make. Moreover, information concerning the operational history of the associated note acceptor is typically not available, apart from a manual count of the money received. Information respecting the experience of a currency validator with respect to jams, attempts at illegal retrieval or "stringing," or the number of rejections of paper tendered as valid currency remain unknown, but of interest.
In the prior art, it has been known to provide an apparatus and technique for generally associating a currency stacker with a particular currency validator in the context of a note acceptor, such that a count of money received, as well as other operating parameters, can be determined at the time of service by monitoring a memory chip maintained in the note stacker. However, it has been found that such memory chips are given to failure because of static charges which may strike them during transportation. Typically, many such memory chips are insulated from electrical shocks up to 11,000 volts, while the static charges generated from the carpet often reach levels of 22,000 volts or more. Charges of this amplitude can either destroy the data maintained within the memory chip, or destroy the memory chip itself. Since it is most desirable that the note stackers be transported in an environment necessarily conducive to the existence of static charges, there is a need in the art for a structure which assures that the memory chip maintained by the note stacker is properly grounded during times of transport, and only removed from the electrical ground for data transmission when maintained in the currency validator itself, or at an appropriate docking station where the memory is to be read.


A reaction resin composition that can be used for the chemical fastening of anchoring means in boreholes and for construction gluing is described. The composition includes (A) a resin component, which contains at least one radically hardenable compound and at least one epoxy resin, which contains, on average, more than one epoxy group per molecule, and a (B) hardener component, which contains a hardening agent for at least one radical compound and at least one amine. The radically hardenable compound and hardening agent in each case being reaction-inhibiting spatially separated from one another. In an embodiment the composition contains no Cu—, Mn—, and iron compound, and no bridging compound. The ratio of double bond value to epoxy value nDB:nEP in the resin component is between 0.01 and 0.55 or between 5 and 50.

The present invention relates to the composition of a hybrid reaction resin, particularly a composition of a reaction resin based on a composition that can be cured in a radical fashion and an epoxy resin, as well as its use for the chemical fastening of anchoring means in bore holes.
The use of mixtures of reaction resin based on unsaturated polyester resins, vinyl ester resins, on the one side, and based on epoxy resins, on the other side, as glue and adhesive means has been known for quite some time. This generally relates to two-component systems, with one component comprising the mixture of reaction resins and the other component comprising the curing agent for the resin. Other common components, such as fillers, accelerants, stabilizers, solvents including reactive solvents (reactive diluter) may be included in one and/or the other component. Then, by mixing the two components the reaction is initiated with the forming a cured product.
In particular for the chemical fastening technology, e.g., dowel materials, high requirements are set for the reactive resin materials, because in this application the mechanic strength, the adhesion to mineral underground, as well as to other undergrounds, such as glass, steel, and the like, must be very good. One parameter for the evaluation of the mechanical strength and the adhesive features is the so-called pull-out test. A low pull-out value, also called load value, indicates low tensile strength and little adhesion to the underground. When using reactive resin materials as organic binders for mortar and/or dowel materials high load values must be yielded even under harsh conditions, such as low and high temperatures.
In general, two systems are used in the chemical fastening technology. One is based on ethylene-unsaturated compositions that can be polymerized in a radical fashion, which are generally cured with peroxides, and one is based on epoxide amines. The first system is characterized in a raid curing process, particularly at low temperatures (−10° C.) and is advantageous with regards to load values, particularly at elevated temperatures such as +80° C. for example, however it shows shrinkage, which cannot be ignored. Contrary thereto, the epoxide amine-systems show a slow curing process, particularly at low temperatures (+5° C.) and weaknesses in the load values, particularly at elevated temperatures, such as +80° C., however they develop considerably less shrinkage.
In order to combine the advantages of both systems developments are ongoing in order to develop dual-curing binders. This means, systems with their curing being based both on radical methods as well as on poly-addition. These systems are also called hybrid systems or hybrid binders. These hybrid systems are generally based on resin compositions, which comprise compounds, which can be cured according to the first reaction type, for example compounds that can be radically polymerized, and compounds that can be cured according to a reaction type that is different from the first reaction type, such as compositions polymerizing via poly-addition, for example epoxides. The resin composition based on a compound that can be radically polymerized, and an epoxy that can be cured for example with a peroxide and an amine.
It has not been achieved in prior art to combine the two classic systems to a simple and ready-to-use hybrid system without significantly adjusting and/or altering the classic systems with regards to their formulation, and thus being forced to tolerate the worsening of certain essential features (such as stability at storage conditions, reactivity at high or low temperatures, etc.).
A reaction resin mortar-composition based on a hybrid binder is known from EP 10153243 A1. The hybrid binder is based on a system with a resin component, which comprises a resin that can be radically cured and an epoxy resin, and which includes a curing component, which comprises an aliphatic amine and a peroxide. This reaction resin mortar-composition shows some disadvantages, though.
It is disadvantageous in this reaction resin mortar-composition that the radical polymerization must be activated with the peroxide as the initiator using an accelerator based on a metal salt, in order for the radical polymerization being initiated at room temperature and particularly at low temperatures up to −10° C. According to EP 10153243 A1 this accelerator is included in the resin component, which comprises the radically curable composition.
Another disadvantage of this reaction resin mortar-composition is further that an additional compound is required, which carries two functional groups, with one of them being able to react in a radical (co)polymerizing fashion and the other one to react with an amine, a so-called bridging compound, in order to also improve curing features at low temperature, in addition to the characteristics of the cured material at low temperatures. It has shown that only with this bridging bond satisfactory load values can be yielded at low temperatures.
Further it is disadvantageous that the gel time of the reaction resin mortar-composition can only be extended with stable nitroxyl radicals, because with the common inhibitors, used in addition to the nitroxyl radicals, any extension of the gel time is not possible.
This leads to additional problems, Frequently compounds are added to the resins and/or the resin components which prevent any early radical polymerization, i.e. during storage, in order to provide them with a suitable shelf life. A common and proven compound is 4-hydroxy-2,2,6,6-tetra methyl piperidine-1-oxyl (Tempol), which is used, among other things, to adjust the gel time of a radically curing, unsaturated resin to the desired value. However, it is assumed that in the reaction resin mortar-composition according to EP 10153243 A1 the Tempol, added at least for the adjustment of the gel time, is relatively quickly disintegrated, preventing any lasting extension of the gel time, and a gel time drift is observed. From literature (e.g., Sheldon et al., Org. Biomol. Chem., 2003, 1, 3232; E.G.
Rozantsev et al., Russ. Chem. Rev., 1971, 40 (3), 233) indications are discernible that Tempol reacts with Cu(I) and Cu(II)-salts, which are used, among other things, as catalysts for the activation of the peroxide curing agent, primarily in the presence of the oxygen of the air with OH-functional substances (which are also contained in common mixtures of reaction resins). A quick oxidation reaction is assumed at room temperature. This disintegrating reaction is also assumed for other stable nitroxyl radicals.
The objective of the invention is therefore to provide a reaction resin system, particularly an injection system, for the chemical fastening, which is free from the above-mentioned disadvantages, can be particularly easily yielded from the combination of the reaction resin systems of prior art, and accordingly shows a simple composition, without here the features of the individual reaction resin systems being negatively influenced.

Reaction resin composition and use thereof


An improved endoscopic ligature provided with a loop support means for stabilizing the shape, position and orientation of a suture loop. The stabilized loop is impervious to surface tension forces created by body fluids and will not close on itself or stick to moist surfaces. When the loop is cinched closed it dislodges from the support. The loop support is made of a flexible material with shape memory and has an unstressed width greater than that of the trocar cannula. The loop support is collapsible to allow the instrument to be inserted and withdrawn through the cannula.

The last decade has seen dramatic advances in the field of endoscopic instrumentation, and the application of endoscopic techniques to a growing number of surgical procedures. The benefits--reduced pain and discomfort, shortened recovery time and better cosmetic results--insure that endoscopic surgery will continue to be a rapidly developing and widely applied technique.
Endoscopic surgery is performed with elongated instruments inserted through small holes in the skin, and is viewed through a video monitor. Therefore, such operations require more mental and physical dexterity than corresponding traditional surgical techniques. Because of these additional difficulties it is important to provide surgical tools that are as trouble free and easy to use as possible.
In endoscopic suturing, the knot must be secure and should be as small as possible to prevent tissue reaction. Stress to the suture weakens its strength and should be minimized. Any crimping or crushing of the suture, or any "sawing" between strands during the knot tying process is to be avoided. If the suture must pass through tissue the knot tying can be done extracorporeally or intracorporeally. If ligation is required a slipknot can be tied in the suture beforehand. Ligation is clearly the simpler suturing technique and therefore the method of choice when there is an option. Endoscopic ligatures are used to ligate vessels and tissue pedicles and to close the openings of cystic structures to prevent spillage contamination.
The state of the present technology in endoscopic ligating instruments is represented by the ENDOLOOP.TM. manufactured by Ethicon, a Johnson & Johnson Company, and the Surgitie.TM. Ligating Loop manufactured by Auto Suture Company, a division of United States Surgical Corporation. These endoscopic ligating instruments have an elongated bored staff with a suture threaded therethrough, the suture forming a loop at the intracorporeal end of the staff. The trocar is provided with a seal mechanism which can form an air-tight seal with the instrument upon insertion of the instrument into the cannula of the trocar. The segment of the staff extending past the seal remains outside the body during surgery and is used as a handle to position the loop. At the extracorporeal end of the staff the suture is connected to a short pull rod that is bonded to the staff. The bond is easily broken by a manual force. The loop is closed by pulling the rod away from the staff.
The instrument is used by placing the loop next to a tissue pedicle or vessel, gripping the tissue with a grasping tool, pulling the grasped tissue through the loop and tightening the loop by separating the pull rod from the staff and pulling it away from the staff.
A drawback of these instruments is that the flexibility of the suture necessary for ligature purposes makes the position and configuration of the loop susceptible to surface tension forces exerted by body fluids. In particular, the surface tension can cause a suture to collapse on itself, closing the loop. It is then difficult to reopen the loop with endoscopic tools, and such manipulations present the risk of inadvertently stressing the suture. Also a wetted suture will tend to adhere to wet surfaces, making it difficult to position the loop in close proximity to tissue. This problem is compounded by the fact that when the suture is wetted, the moisture softens the material. Gut suture is somewhat more impervious than braided Nylon or silk to this softening problem.


A conveyor pocket for a hanging conveyor system, in particular for the transport of conveyor articles hanging on hangers, having a pawl (3) which is arranged swingably in a base body (2) and is provided for holding in each case only one carrier on its hook-shaped head region (hook 20), the pawl (3) having an extension (4) protruding from the base body (2) for the swinging of the pawl (3) and thus the opening of the conveyor pocket (1), is characterized by the fact that the pivot axis (7) of the pawl (3) is arranged behind the resting point (15) of the hook (20) on the pawl (3) as seen in direction of transport (T).

The present invention relates to a carrier device such as a conveyor pocket for a hanging conveyor system, in particular for transporting conveyed articles hanging on hangers, having a pawl which is pivoted in a base body, each pawl being intended to support one hanger by its hook-shaped head region (hook), the pawl having an extension protruding from the base body in order to swing the pawl and thus open the conveyor pocket. The invention furthermore relates to a method of introducing a hanger having a hook-shaped head region, and particularly a clothes hanger, into a conveyor pocket within an endlessly rotating hanging conveyor.
A conveyor pocket of this type is disclosed in EP-A 0 307 045, incorporated by reference herein. That conveyor pocket is designed, in particular, for conveying articles of clothing hanging on clothes hangers. During transportation, the hanger hook rests on the pawl. In order to prevent the hook from falling out of the conveyor pocket, the pocket can be closed by a tongue. This tongue is swingable in the direction opposite the direction of transport, so that the hanger hook can be introduced from the front into the receiving region of the conveyor pocket by swinging the closure pawl out of the way. The pawl is blocked in the direction of transport so that the hanger or hanger hook cannot fall out of the conveyor pocket during transport. In removing the hanger from the conveyor pocket, the pawl on which the hanger hook rests during transport is swung away in the direction opposite to the direction of transport, the hanger hook being gripped by the arm of the base body of the conveyor pocket and then sliding out of the conveyor pocket onto a removal bar which is arranged laterally alongside the conveyor line. In order to prevent the pawl from opening during transport by the weight of the hook resting on it, a closure spring is provided in the base body, the spring holding the pawl in its closed position.
There is the problem here that the hanger is imparted a negative acceleration upon the stripping off in the conveyor pocket. In order for it to reliably emerge from the delivery region, the slide bar must accordingly have a correspondingly large slope, which cannot always be easily realized due to considerations of space. Furthermore, the closure spring must be designed for the maximum load to be transported. Correspondingly high opening forces are necessary. If the force of the spring decreases during the course of operation, then, in particular, heavy articles of clothing can no longer be reliably conveyed. Due to the large number of structural parts, the known conveyor pocket is rather complicated in construction. Automatic loading of the conveyor pocket is not possible or is possible only with extremely complicated runs.


The present invention provides a method for producing hydroxyl group-containing polymer particles including causing cross-linked polymer particles containing a (meth)acrylate polymer to react in the presence of a metal-containing ester-exchange reaction catalyst with at least one compound selected from the group consisting of a compound including at least two hydroxyl groups and a compound including at least one primary amino group and at least one hydroxyl group, the cross-linked polymer particles comprising the (meth)acrylate polymer represented by the following formula (I):

1. Field of the Invention
The present invention relates to a method for producing cross-linked polymer particles containing hydroxyl groups that can be applied to good effect in fields such as carriers of diagnostic agents and pharmaceuticals, carriers for chromatography, viscosity-controlling agents, resin-molding materials, paint additives, cross-linking/hardening agents and additives for cosmetics.
2. Description of the Related Art
Conventionally two methods have been used for producing polymer particles containing hydroxyl groups. According to the first method, polymer particles are initially formed by suspension-polymerization of monomers containing functional groups that can be converted into hydroxyl groups in an aqueous medium, and the functional groups are then converted into hydroxyl groups. According to the second method, cross-linked polymer particles containing reactive functional groups are formed, and the hydroxyl groups are then introduced into the particles by causing a hydroxyl group-containing compound to react with the reactive functional groups and thus to be linked to the particles.
Examples known in the art of polymer particles produced by the first method include porous and spherical separation carriers obtained either by homo-polymerization of an aqueous suspension of pentaerythritol dimethacrylate, or by aqueous co-polymerization of pentaerythritol dimethacrylate with a methacrylate monomer containing hydrophilic groups and/or groups that can be converted into hydrophilic groups (for example, see Japanese Patent Application Publication (JP-B) No. 61-36177). However, since pentaerythritol dimethacrylate is not industrially manufactured on a large scale, users first need to manufacture pentaerythritol and thus the process becomes complicated.
In a variation of the first method disclosed, ester groups of a co-polymer obtained by co-polymerization of carboxylic acid vinyl ester monomers and cross-linking monomers containing isocyanulate rings are converted into hydroxyl groups by saponification (for example, see JP-B No. 2-19902). However, the hydroxyl group obtained by saponification of the carboxylic acid vinyl ester is restricted to a polyvinyl alcohol-type hydroxyl group directly linked to the main chain, and a drawback of this method is that chemical structures surrounding the hydroxyl group cannot be modified. In addition, since carboxylic acid salts cannot easily be removed from the inside of the particles after alkali-hydrolysis, the process used by following this method has also tended to become complicated.
As the second method disclosed for producing the hydrophilic separation carrier containing the hydroxyl groups, a cross-linked co-polymer of (meth)acrylic acid ester containing glycidyl groups is made to perform a ring-opening reaction with polyethyleneglycol or glycerin (Japanese Patent Application Laid-open (JP-A) No. 60-96605). However, since a reactive functional group such as the glycidyl group tends to cause side reactions, and it becomes difficult to control the amount of the hydroxyl group, the properties of the desired particles have tended to be adversely affected. Furthermore, (meth)acrylic ester containing a glycidyl group is toxic and its use is not desirable in terms of safety or hygiene.
In a variation of the second method disclosed, fine particles of a cross-linked polymer containing reactive functional groups, selected from an epoxy group (such as the glycidyl group), an hydroxyl group and a carboxylic group are made to react with a polyethyleneglycol (Japanese Patent Application Laid-Open (JP-A) No. 5-1106). However, control of the amount of the hydroxyl group and control of particle properties as the object of the method are difficult, insofar that in this production method the hydroxyl group originating from polyethyleneglycol, and the hydroxyl group and carboxylic group inherent in the particles tend to become mixed together. Moreover, use of an epoxy group (such as the glycidyl group) also entails the same problems as with the use of a glycidyl group.
Conventional production methods for obtaining hydroxyl group-containing polymer particles have thus so far entailed the problems described above.

Method for producing hydroxyl group-containing polymer particles

Abstract: wherein R1 represents a hydrogen atom or a methyl group; R2 to R4 may be the same or different from each other, and each independently represents a substituted or non-substituted alkyl group or a substituted or non-substituted aryl group, any one of which has 1 to 12 carbon atoms; and n represents an integer of 1 or more.


A method for operating a camera network having a plurality of cameras, comprising the steps of: communicating with the plurality of cameras to determine one or more operation parameters for each of the plurality of cameras; synchronizing the one or more operation parameters for each of the plurality of cameras; and coordinating a capture of multimedia data using the plurality of cameras with the one or more synchronized operation parameters.

Cameras are optical instruments used for capturing still or moving images (and/or sound). Generally, cameras can be classified into two main categories, a point and shoot (P&S) type and a single lens reflex (SLR) type. Both of these types are now predominantly digital, but they may also use film to record an image.
P&S type cameras have all the optical and/or electrical instruments arranged in the camera body and the operation of P&S type camera is largely automatic. Users of P&S cameras can readily capture images by pointing the camera to the object or image to be captured and actuating the shutter. Thus, P&S cameras are simpler for use and are relatively small in size and more compact.
SLR type cameras, on the other hand, allow a larger degree of user manipulation as the lens of these cameras is readily changeable. Users of SLR cameras will often have to manipulate the optical and/or electrical instruments of the cameras before capturing an image. Thus, the quality of images taken using SLR cameras will often depend on the photographic skills of the user. Also, SLR cameras are relatively large and more bulky compared with P&S cameras.
Nonetheless, in some photographic (photo or video) applications, it may be necessary to capture still or moving images using different cameras at the same time. However, different types of cameras (or different varieties of cameras of the same type) will often have different operation characteristics. This presents a significant challenge for realizing real time synchronous/synchronized photographic (photo or video) shooting with a plurality of cameras of different types.

Camera network and method of operating thereof


The invention is to provide a process for industrially advantageously producing InP fine particles having a nano-meter size efficiently in a short period of time and an InP fine particle dispersion, and there are provided a process for the production of InP fine particles by reacting an In raw material containing two or more In compounds with a P raw material containing at least one P compound in a solvent wherein the process uses, as said two or more In compounds, at least one first In compound having a group that reacts with a functional group of P compound having a P atom adjacent to an In atom to be eliminated with the functional group in the formation of an In-P bond and at least one second In compound having a lower electron density of In atom in the compound than said first In compound and Lewis base solvent as said solvent, and InP fine particles obtained by the process.

In recent years, semiconductor crystallites (fine particles) are drawing attention and are being actively studied. Semiconductor crystallites have a characteristic feature that the emission wavelength of one material can be controlled by controlling the particle size of the material on the basis of quantum confinement effects, and they are expected to be luminescence center materials.
Of these, CdSe crystallite is easily produced and the particle size of CdSe is also relatively easily controllable, so that it has high utility and studies thereof have been advanced. However, the defect thereof is that it has toxicity derived from Cd.
On the other hand, InP crystallite is free of the toxicity problem that Cd has, so that it draws attention for a new luminescence center.
As a method for synthesizing InP, various methods have been known. For example, there are reports of (1) a method in which a mixture of P((CH2)7CH3)3 with OP(CH2)7CH3)3 is used as a solvent, InCl(COO)2 is used as an In material, P(Si(CH3)3)3 (to be sometimes referred to as "P(TMS) 3" hereinafter) is used as a P material and these materials are reacted at 260 to 300° C. for 3 to 6 days to synthesize InP (for example, see "J. Phys. Chem.", Vol. 98, page 4966 (1994)) and (2) a method in which In(OR)3 is used as an In material, excess P(TMS)3 is used as a P material and these materials are reacted in a boiling pyridine solution to directly synthesize amorphous InP (specifically, InP[P(TMS)3]x) soluble in toluene (for example, see "Polyhedron" Vol. 13, page 1131 (1994)).
However, the above method (1) takes a long time for the synthesis and is poor in productivity, so that it cannot be said that the method (1) is satisfactory in industrial practice. In the method (2), further, generated InP is amorphous and cannot be used as a light-emitting material for the luminescence center.
InP particles obtained according to any conventional method have defects that they are poor in dispersibility in a solution and are liable to precipitate during a reaction.
On the other hand, as a dry process, there is known a method in which InP is formed by a physical vapor deposition method (PVD method) or a chemical vapor deposition method (CVD method). In these methods, however, not only an expensive apparatus is required but also it is difficult to accurately control the atomic ratio of In and P, so that there is a defect that it is difficult to obtain InP having predetermined performances.

Process for the production of InP fine particles and InP fine particle dispersion obtained by the process


A fabricating method of an ion sensitive field effect transistor (ISFET) with a Ta.sub.2 O.sub.5 hydrogen ion sensing membrane, which comprises the steps of forming Ta.sub.2 O.sub.5 film with a thickness of about 400 to 500 A by RF reactive sputtering on a Si.sub.3 N.sub.4 /SiO.sub.2 gate dielectric layer of the pH-ISFET, and annealing the resultant film at about 375.degree. to 450.degree. C. in oxygen gas ambience for about one hour. In forming the Ta.sub.2 O.sub.5 film on the pH-ISFET, the Ta.sub.2 O.sub.5 film formed in the area except the gate region of the pH-ISFET is removed by a lift-off process utilizing a positive PR film. The Ta.sub.2 O.sub.5 gate pH-ISFET according to the present invention has higher sensitivity and more stable operation characteristics than those of the conventional pH-ISFET, while the productivity and stability thereof are greatly improved by effecting a whole wafer process.

1. Field of the Invention
The present invention relates to a method of fabricating an ion sensitive field effect transitor (ISFET) with a Ta.sub.2 O.sub.5 hydrogen ion sensing membrane, and more particularly to a method of fabricating a pH-ISFET with a Ta.sub.2 O.sub.5 hydrogen ion sensing membrane having high sensitivity and stable operating characteristics.
2. Description of the Prior Art
ISFETs have been developed as a kind of semiconductor ion sensor manufactured by utilizing the manufacturing process of semiconductor integrated circuits and have such characteristics that they are very small in size and light in weight, and thus they can be normally used as ion sensors for in-vivo measurements, being adapted for insertion into the human bloodstream.
Further, the ISFETs have the merits like economic mass production, easy standardization, etc., and thus the ISFET ion sensors can be substituted for existing expensive ion selective electrodes (ISEs). At present, such ISFETs are widely used in the fields of medical treatment, analytical chemistry, environmental management, etc.
The ISFET was firstly reported by P. Bergvelt in 1970, as a result of his preliminary research for an ion sensitive solid-state device for neurophysiological measurements and thereafter, the research was concretely and practically done by Matsuo, Wise, et al.
Table 1 shows sensing characteristics of hydrogen ion sensing membranes of the several pH-ISFETs. According to Table 1, the SiO.sub.2 membrane has low sensitivity as well as severe drift, while the ZrO.sub.2 membrane has a narrow range of pH measurements, and thus they are not generally used.
In comparison with these membranes, the Si.sub.3 N.sub.4 membrane can easily be deposited on the gate of the ISFET as a chemically stable dielectric layer, and thus the current leakage through its gate and the hydration in its surface can be reduced, thereby resulting in a stable sensing operation.
However, deterioration in sensing characteristics may be expected in Si.sub.3 N.sub.4 film depending upon its stoichiometric composition ratio under the specific film depositing condition and storage condition in case that the film is made through low pressure chemical vapor deposition (hereinafter, referred to as LPCVD) process. In other words, under the influence of surface oxidation and non-stoichiometric composition in the film surface, the undesirable hydration may be caused, thereby lowering its sensitivity and greatly increasing the drift.
In order to solve the problem of such disadvantages of Si.sub.3 N.sub.4 membrane, researches of Al.sub.2 O.sub.3 and Ta.sub.2 O.sub.5 thin films which are metal oxides, have been actively carried out.
The Ta.sub.2 O.sub.5 thin film has much better sensing characteristics than those of other ISFET hydrogen ion sensing membranes and further, it has the advantage that the deterioration of its characteristics due to its surface oxidation are not found, differently from those of the Si.sub.3 N.sub.4 membrane even when it is exposed to the open air. However, it has the disadvantage that its sensing characteristics would be affected by the film depositing method and its annealing condition.
TABLE 1 ______________________________________ (Sensing characteristics of ion sensing membranes of the pH-ISFETs) sensing membrane characteristics SiO.sub.2 Si.sub.3 N.sub.4 Al.sub.2 O.sub.3 ZrO.sub.2 Ta.sub.2 O.sub.5 ______________________________________ possible 4-10 1-13 1-13 0-8 1-13 range of pH measurement sensitivity 25-35 46-56 53-58 50-58 56-58 (mV/pH) response time 1 <0.1 <0.1 >0.1 <0.1 (95%, sec) long-term unstable 3.0 0.8 stable 0.2 stability (mV/h, pH 7) ______________________________________
Conventional methods of depositing the Ta.sub.2 O.sub.5 thin film is divided roughly into two groups; RF sputtering process and chemical vapor deposition (CVD) process.
Ta.sub.2 O.sub.5 film can be formed by thermal CVD, plasma enhanced CVD (PECVD), photo CVD or low pressure CVD (LPCVD) process among the various CVD processes.
Generally, the CVD processes provide such advantages as the formation of the film in that the film is excellent in its stoichiometric composition and in its productivity. However, the equipment for this process is very expensive and complicated, and thus it is difficult to determine the optimum deposition parameters. Further, it has the disadvantage that the gas to be used is costly and consuming.
On the other hand, the equipment for the RF sputtering process is relatively inexpensive and easy operate according to its simple structure, but this process has the disadvantages that it is difficult to effect the desired stoichiometric composition and to avoid the damage on the film surface caused by its plasma process and resulting lower productivity.
Japanese Patent Laid-open No. 62-245956 published on Oct. 27, 1987 discloses a pH-ISFET sensor in which Ta.sub.2 O.sub.5 hydrogen ion sensing membrane is deposited by the RF sputtering process.
According to the above-mentioned invention, the Ta.sub.2 O.sub.5 thin film of the ISFET is deposited by the RF sputtering process, but it is difficult to improve the stoichiometric composition ratio of tantalum and oxygen and this causes a decrease in the sensitivity of the pH-ISFET sensor. In that invention, after deposition step, the film is annealed at a temperature of 275.degree.-300.degree. C. in an inert gas (e.g. nitrogen or argon gas) ambience for 10 minutes. However, its annealing temperature is too low to obtain the desired annealing effect. Also, the Ta.sub.2 O.sub.5 film lacks oxygen, which means that it suffers from a non-stoichiometric composition ratio. Accordingly, it gives a definitive influence to the sensitivity and stability of the sensor as the sensing mechanism of the ISFET is a kind of site binding depending upon the condition of the sensing membrane surface.
Therefore, under the above-mentioned annealing condition, the sensors undergo undesirable influences in the sensitivity and the stability thereof. Further, during the deposition of the Ta.sub.2 O.sub.5 thin film, the bonding region of the ISFET except its gate region is covered with a mask and then sputtered. Such process utilizing the mask is not a whole wafer process by photo etching, but is carried out manually, and then it is troublesome in productivity and standardization.

Method of fabricating an ion sensitive field effect transistor with a Ta.sub.2 O.sub.5 hydrogen ion sensing membrane


A magnetic tunnel junction (MTJ) sensor in which the free layer longitudinal biasing elements are coupled, without insulation, to the free layer outside of the MTJ stack to provide reliable non-shunting MTJ free layer stabilization without extremely thin dielectric layers. In one embodiment, hard magnetic (HM) layers are disposed in contact with the free layer outside of and separated from the MTJ stack active region by a thick dielectric layer. In another embodiment, antiferromagnetic (AFM) bias layers are disposed in contact with the free layer outside of and separated from the MTJ stack active region by a thick dielectric layer. In other embodiments, nonconductive HM layers are disposed either in contact with the free layer outside of the MTJ stack active region and/or in abutting contact with the MTJ stack active region.

1. Field of the Invention
This invention relates generally to a magnetic tunnel junction (MTJ) device and more particularly to an MTJ device for use as a magnetoresistive (MR) head for reading magnetically-recorded data.
2. Description of the Related Art
Computers often include auxiliary memory storage devices having media on which data can be written and from which data can be read for later use. A direct access storage device (DASD or disk drive) incorporating rotating magnetic disks is commonly used for storing data in magnetic form on the disk surfaces. Data is recorded on concentric, radially spaced tracks on the disk surfaces. Magnetic heads including read sensors are then used to read data from the tracks on the disk surfaces.
In high capacity disk drives, magnetoresistive (MR) read sensors (MR heads) are preferred in the art because of their capability to read data at greater track and linear densities than earlier thin film inductive heads. An MR sensor detects the magnetic data on a disk surface through a change in the MR sensing layer resistance responsive to changes in the magnetic flux sensed by the MR layer.
The early MR sensors rely on the anisotropic magnetoresistive (AMR) effect in which an MR element resistance varies as the square of the cosine of the angle between the magnetic moment of the MR element and the direction of sense current flowing through the MR element. Recorded data can be read from a magnetic medium because the external magnetic field from the recorded magnetic medium (the signal field) changes the moment direction in the MR element, thereby changing the MR element resistance and the sense current or voltage.
The later giant magnetoresistance (GMR) sensor relies on the spin-scattering effect. In GMR sensors, the resistance of the GMR stack varies as a function of the spin-dependent transmission of the conduction electrons between two magnetic layers separated by a non-magnetic spacer layer and the accompanying spin-dependent scattering that occurs at the interface of the magnetic and non-magnetic layers and within the magnetic layers. GMR sensors using only two layers of ferromagnetic (FM) material separated by a layer of non-magnetic conductive material (e.g., copper) are generally referred to as spin valve (SV) sensors.
In 1995, a new class of high magnetoresistive (MR) materials was discovered in which the nonmagnetic layer separating the two FM layers is made with an ultrathin nonconductive material, such as an aluminum oxide layer <20 Å thick. With the switching of magnetization of the two magnetic layers between parallel and antiparallel states, the differences in the tunneling coefficient of the junction and thus the magnetoresistance ratio have been demonstrated to be more than 25%. A distinctive feature of this magnetic tunnel junction (MTJ) class of materials is its high impedance (>100 kΩ-μm2), which allows for large signal outputs.
A MTJ device has two ferromagnetic (FM) layers separated by a thin insulating tunnel barrier layer. MTJ operation relies on the spin-polarized electron tunneling phenomenon known in the art. One of the two FM layers (the reference layer) has a higher saturation field in one direction because of, for example, a higher coercivity, than the other FM layer (the sensing layer), which is more free to rotate in response to external fields. The insulating tunnel barrier layer is thin enough so that quantum mechanical tunneling occurs between the two FM layers. The tunneling phenomenon is electron-spin dependent, making the magnetic response of the MTJ a function of the relative moment orientations and spin polarizations of the two FM layers.
When used as memory cells, the MTJ memory cell state is determined by measuring the cell resistance to a sense current passed perpendicularly through the MTJ from one FM layer to the other. The charge carrier probability of tunneling across the insulating tunnel barrier layer depends on the relative alignment of the magnetic moments (magnetization directions) of the two FM layers. The tunneling current is spin polarized, which means that the electrical current passing from one of the FM layers, for example, the reference layer whose magnetic moment is pinned to prevent rotation, is predominantly composed of electrons of one spin type (spin up or spin down, depending on the reference orientation of the magnetic moment). The degree of spin polarization of the tunneling current is determined by the electronic band structure of the magnetic material composing the FM layer at the interface of the FM layer with the tunnel barrier layer. The FM reference layer thus acts as a spin filter for tunneling electrons. The probability of tunneling of the charge carriers depends on the availability of electronic states of the same spin polarization as the spin polarization of the electrical current in the FM sensing layer. When the magnetic moment of the FM sensing layer is parallel to that of the FM reference layer, more electronic states are available than when the two FM layer magnetic moments are antiparallel. Accordingly, charge carrier tunneling probability is highest when the magnetic moments of both layers are parallel and is lowest when the magnetic moments are antiparallel. Between these two extremes, the tunneling probability assumes some intermediate value, so that the electrical resistance of the MTJ memory cell depends on both the sense current spin polarization and the electronic states in both FM layers. As a result, the two orthogonal moment directions available in the free FM sensing layer together define two possible bit states (0 or 1) for the MTJ memory cell. Serious interest in the MTJ memory cell has lagged for some time because of difficulties in achieving useful responses in practical structures at noncryogenic temperatures.
The magnetoresistive (MR) sensor known in the art detects magnetic field signals through the resistance changes of a read element, fabricated of a magnetic material, as a function of the strength and direction of magnetic flux sensed by the read element. The conventional MR sensor, such as that used as a MR read head for reading data in magnetic recording disk drives, operates on the basis of the anisotropic magnetoresistive (AMR) effect of the bulk magnetic material, which is typically permalloy (Ni81 Fe19). A component of the read element resistance varies as the square of the cosine of the angle between the magnetization direction in the read element and the direction of sense current through the read element. Recorded data can be read from a magnetic medium, such as the disk in a disk drive, because the external magnetic field from the recorded magnetic medium (the signal field) causes a change in the direction of magnetization in the read element, which in turn causes a change in resistance of the read element and a corresponding change in the sensed current or voltage.
The use of an MTJ device as a MR read head is also well-known in the art. One of the problems with the MTJ read head is the difficulty encountered in developing a sensor structure that generates an output signal that is both stable and linear with respect to the magnetic field strength sensed in the recorded medium. Some means is required to stabilize the magnetic domain state of the MTJ free FM sensing layer to prevent unacceptable Barkhausen noise arising from shifting magnetic domain walls within the free sensing layer. Also, some means for achieving a substantially linear response of the head is necessary for acceptable sensitivity. The longitudinal stabilization problem is particularly difficult in an MTJ MR read head because, unlike an AMR sensor, the MTJ sense current passes perpendicularly through the stack of FM and tunnel barrier layers so that any metallic materials in direct contact with the edges of the FM layers act to shunt (short-circuit) the read head sense resistance.
Practitioners have proposed several methods for resolving these problems to permit the use of MTJ sensors in magnetic read head applications. For example, in U.S. Pat. No. 5,729,410 (and later, in U.S. Pat. No. 6,005,753), Fontana, Jr. et al. describe a MTJ device where the sensing (free) FM layer magnetic moment is longitudinally biased by a layer of hard FM material located near but separated slightly from the side edges thereof (and later, from the back edge thereof for added transverse biasing) by an intervening layer of electrically insulating material. The insulating layer isolates the hard biasing material from the electrical leads and the sensing FM layer to prevent shunting of the sense current to the hard biasing material without interfering with the perpendicular sense current flow through the layers in the stack. Similarly, in U.S. Pat. No. 6,097,579, Gill proposes sandwiching a permanent magnet layer between two thin dielectric layers to provide longitudinal baising of the MTJ free layer. However, the Fontana, Jr, et al. and the Gill approaches are problematic to manufacture because they generally rely on extremely thin insulation layers to allow sufficient magnetostatic coupling to reduce Barkhausen noise in the free FM layer without shunting the sense current.
FIG. 1A shows an illustrative embodiment of a magnetic tunnel junction (MTJ) sensor 10 from the prior art. Sensor 10 is viewed from the air bearing surface (ABS) so that, in operation, the magnetic medium (not shown) moves in the image plane vertically with respect to MTJ sensor 10. MTJ sensor 10 includes an MTJ stack 12 disposed between a first shield (S1) layer 14 and a second shield (S2) layer 16. MTJ stack 12 may be characterized as an upper electrode 18 separated from a lower electrode 20 by a tunnel barrier 22. Upper electrode 18 includes a ferromagnetic (FM) pinned layer 24 having a magnetic moment that is pinned by an exchange-coupled antiferromagnetic (AFM) layer 26, and a second lead (L2) layer. The lower electrode 20 includes a FM free layer 30 and a first lead (L1) layer 32. MTJ stack 12 operates in the usual manner known in the art except that the stabilization biasing of free layer 30 is provided by a hard magnetic (HM) layer 34 disposed on each side of MTJ stack 12. To prevent a loss of sensitivity from undesired sense current shunting, HM layers 34 are sandwiched between two insulating layers 36 and 38 substantially as shown. Practitioners in the art can readily appreciate that the several layers outside of MTJ stack 12 should be precisely created in a series of steps following an initial etching procedure. The usual processes known in the art give rise to misalignment between the narrow ends of the various layers at the edges of MTJ stack 12, leading to unit performance variations and high unit rejection rates.
FIG. 1B shows an air bearing surface (ABS) view of another illustrative embodiment of a MTJ sensor 40 from the prior art. MTJ sensor 40 can be considered to include the end regions 42 and 44 separated from each other by a central region 46. The active region of MTJ sensor 40 is the MTJ stack 48 formed in the central region 46. MTJ stack 48 has a generally rectangular shape with a front face (shown) at the ABS, a back edge (not shown) opposite to the front edge and two opposite side edges 50 and 52. MTJ stack 40 includes a first electrode 54 and a second electrode 56 between which is disposed a tunnel barrier layer 58. First electrode 54 includes a pinned layer 60, an AFM layer 62 and a seed layer 64, where pinned layer 60 is disposed between tunnel barrier layer 58 and AFM layer 62, which is disposed between pinned layer 60 and seed layer 64. Second electrode 56 includes a free layer 66 and a cap layer 68, where free layer 66 is disposed between tunnel barrier layer 58 and cap layer 68. AFM layer 62 is exchange coupled to pinned layer 60 providing an exchange field to pin the magnetization direction of pinned layer 60 perpendicular to the ABS. The magnetization of free layer 66 is oriented parallel to the ABS (absent other external magnetic fields) and is free to rotate in the presence of a signal magnetic field. As with MTJ sensor 10 (FIG. 1A), free layer stabilization bias is provided by the HB layers 70, which are sandwiched between the insulation layers 72 and 74 to prevent sensitivity losses through shunting of MTJ stack 48.
In U.S. Pat. No. 5,930,087, Brug et al. disclose a flux-guide MTJ sensor having a FM free layer that extends beyond the active region (MTJ stack) to the sides and also to the rear and the front (to the ABS). They suggest in passing that the longitudinal biasing layer placed on the flux guide adjacent to each side of a flux-guide MTJ stack may consist of antiferromagnetic materials such as terbium-iron or nickel-oxide (a nonconductor), but Brug et al. appear to prefer using antiferromagnetic (AFM) manganese compounds or permanent magnetic layers and neither consider nor suggest specific solutions to the MTJ sense current shunting problem arising from such MTJ sensor geometries.
There is accordingly a need in the MR sensor art for an effective MTJ longitudinal biasing technique that can be implemented using simpler, more reliable fabrication methods leading to higher yields and more consistent unit performance without the sensitivity loss arising from sense current shunting. These unresolved problems and deficiencies are clearly felt in the art and are solved by this invention in the manner described below.

Magnetic tunnel junction sensor with insulating antiferromagnetic material extending from free layer extensions to electrically conductive lead

Hitachi Global Storage Technologies Netherlands B.V.


An electronic game board that simulates moves of one or more players includes a top cover that includes a play area onto which game pieces are arranged for facilitating a game. The electronic game board further includes a drive system located beneath the top cover for simulating the moves on the play area by moving at least one game piece from a first position on the play area to a second position on the play area. The drive system includes a robotic arm and first and second actuators for controlling movement of the robotic arm. To simulate the move, the first and second actuators control the movement of the robotic arm such that the game piece is moved from the first position to the second position by way of the robotic arm.

Board games, such as snakes and ladders, chess, go, connect 4, checkers, and ludo, have been played by people of all ages and diversities for several generations. The board games may be played on any physical board, such as a wooden board, or on a computer. When a first player opts to play the board game on a physical board, the first player gets an opportunity to merely play with players that are in the vicinity of the first player. To play with players that are located remotely with respect to the first player, the first player has to rely on the computer.
In the last decade, electronic game boards have become popular owing to the opportunity to play with the remote players on a physical board. The first player thus gets an opportunity to play a board game on a physical board with a second player that is located remotely. Such electronic game boards include a gaming system that controls the operation of the electronic game boards. Thus, when the first player makes a move, the gaming system records the move, communicates the move to the second player, receives a counter move played by the second player, and displays the counter move on a screen of the electronic game board or on a player device of the first player. The first player then moves a game piece of the second player based on the counter move. While this approach provides the first player with a physical experience of playing the game with a remotely located player, it is quite tiresome for the first player to move the game pieces for the second player.
Thus, it would be advantageous to have an electronic game board that enables a player to play with an opponent, who is at a remote location, on a physical board without the need to move the game pieces for the opponent.


An oscillator comprising a dielectric resonator (DR) has a high controllability and reproducibility of coupling between the dielectric resonator (DR) and an oscillation circuit, and an integrated circuit is reduced in size. The dielectric resonator (DR) (1) is composed of a dielectric substrate (2), grounding conductive layers (3a, 3b) formed on both sides of the dielectric substrate (2), and via holes (4a) for electrical connection between the conductive layers. A coupling element (7a) composed of a slot (5a) provided in the central portion of the grounding conductive layer (3a) and a patch (6a) surrounded by the slot (5a) is coupled to the dielectric resonator (DR) (1). The patch (6a) is connected to a transmission line (13a) on an oscillation circuit (9) through a bump (8). The transmission line (13a) is connected to the ground through a termination resistor (15a). On the oscillation circuit MMIC (9), the transmission line (13a) is connected to the gate of a transistor FET (14) A capacitive transmission line (13a) for positive feedback is connected to the transistor FET (14). The output of the transistor FET (14) is connected to a transmission line (13c) for output through a matching circuit (16). The transmission line (13c) is bump-connected to a coplanar line (12a) composed of a signal conductive layer (11a) formed on an edge of the dielectric resonator (DR) (1) and the grounding conductive layer (3a).

All of patents, patent applications, patent publications, scientific articles and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by references in their entirety in order to describe more fully the state of the art, to which the present invention pertains.
A dielectric resonator (DR) is used in an oscillator used in a microwave band and in a millimeter wave band for increasing stabilities for a phase noise and the frequency. FIG. 1 is an equivalent circuit showing a configuration of the oscillator using the dielectric resonator (DRO) according to one conventional example. For obtaining a negative resistance, a capacitive micro strip line 28b is connected to a source of transistor FET 14. A micro strip line 28a extending from a gate of transistor FET 14 is inductively coupled with a dielectric resonator 1 having TE01d mode of cylindrical shape. In this configuration, a coupling rate is adjusted by a distance between dielectric resonator 1 and micro strip line 28a. Electromagnetic waves from transistor FET 14 are reflected at a resonant frequency of dielectric resonator 1, and absorbed with termination resistor 15a at a frequency other then the resonant frequency. Therefore, there exists a large negative resistance at the resonant frequency. Matching circuit 16 (which comprises a transmission line and a capacitor) being designed to comply an oscillation condition is connected to a drain of transistor FET 14. Gate bias 17a and drain bias 17b of transistor FET 14 are applied through resistor 15b of several kO and matching circuit 16, respectively. In addition, a resonant frequency is finely tuned by varactor diode 20 connected to one terminal of micro strip line 28c which is inductively coupled with dielectric resonator 1. Capacitor 21a having a low reactance at an operating frequency is connected to one side of varactor diode 20, add resistor 15c having several kO which is DC grounded is connected to the other side. In this configuration, because the resonant frequency of dielectric resonator 1 is determined by an outside dimension of the resonator, a high machining accuracy is required for the resonator. Also, since the coupling rate is tuned by the distance between dielectric resonator 1 and micro strip line 28a, a high positioning accuracy (0.1 mm) of dielectric resonator 1 is required. In addition, as a electromagnetic field is spread out of the resonator, the oscillation frequency is easily changed when the resonator is mounted on a package.
Then, as a bonding structure of a dielectric resonator and a transmission line, a structure shown in FIG. 2 has been proposed in Japanese Laid-open Patent Publication No. 11-145709. FIG. 2 is an exploded perspective view showing a bonding structure of a dielectric resonator and a transmission line according to another conventional example. Dielectric resonator 1 comprises dielectric substrate 30 and conductive plates 29a, 29b. Conductor layers 31a, 31b having circular apertural parts facing to each other are formed on both upper surface and bottom surface of dielectric substrate 30. Dielectric layer 32 is formed on conductive layer 31a using a thin film formation technology. In addition, signal conductive layer 33 is formed on dielectric layer 32. In this configuration, the apertural part of dielectric substrate 30 operates as a resonator. In the Japanese Laid-open Patent Publication No. 11-145709, as with the configuration in FIG. 1, the coupling rate is tuned by a distance between the resonator and signal conductive layer 33. However, because a position of signal conductive layer 33 can be controlled accurately using a thin film formation technology, a variation of the coupling rate is small.
On the other hand, in the example of the Japanese Laid-open Patent Publication No. 11-145709, even though spread of the electromagnetic filed out of the resonator is small compared with a dielectric resonator which has a cylindrical shape, the electromagnetic filed also spreads out upward and bottomward. Therefore, it has been necessary that, for example, lines and a transistor FET other than a resonator, which compose the oscillator, have to be arranged keeping some distance from the resonator. That is, the lines and the transistor FET can not be disposed in upward and bottomward of the resonator, thereby resulting in large size of the circuit. In addition, for the purpose of electrical shielding, conductive plates 29a, 29b covering a resonator portion are separately needed as shown in FIG. 2.

Dielectric resonator, dielectric resonator frequency adjusting method, and dielectric resonator integrated circuit


A bidirectional AC series voltage regulator that regulates an output AC voltage level regardless of the varying AC input voltage utilizing high frequency series inductors that only process a proportion of the total output power. The AC series voltage regulator detects the power inductor current direction data signal and can generate power inductor current direction data signals for its control to determine the AC input voltage polarity at all time; wherein the determination of the AC input voltage polarity is unambiguous during the AC input voltage zero crossover and near zero points; and wherein the determination of the AC input voltage polarity allows normal switching sequence of the AC bidirectional switches during the AC input voltage zero crossover and near zero points to prevent power “shoot-through.”

AC voltage regulators are used to closely control and regulate the AC voltage level being delivered to a load connected to the output of the AC voltage regulator, regardless of the AC voltage variation at the input of the AC voltage regulator.
This has been traditionally done by various low frequency (LF), typically at 50 or 60 Hz, electrical mains magnetic structures. These structures are typically tapped at specific discrete transformer voltage taps in various transformers or transformer configurations. Nonetheless, all these structures rely on traditional AC switching devices such as relays or semiconductor devices such as silicon-controlled rectifiers (SCR)'s or gate turn off thyristor (GTO)'s connected as anti-parallel AC switches, TRIAC's, AC switches such as insulated-gate bipolar transistors (IGBT)'s, MOSFET transistors, and SCR's configured as AC switches, e.g. connected between rectifiers. These AC switches are selected and activated by the electronic control circuit to automatically switch the selected magnetic transformer structure tap, in turn adjusting the transformer or transformer configuration turns ratio to control the AC output voltage as close as possible to the desired level.
Another traditional method to regulate an output AC voltage is to use an electro-mechanically-adjusted auto-transformer that is driven by electrical mechanical means, such as a controlled electrical motor. The electronic control in this case senses the input voltage and then drives the electro-mechanical means to move the output contact to adjust the turns of the auto-transformer, in turn sets the correct turns ratio to fix the output AC voltage to the desired level. These electro-mechanically-adjusted auto-transformer devices are also LF magnetic structures, typically at 50 Hz or 60 Hz, and generally use carbon brushes to make the moving electrical contact to the auto-transformer windings. These brushes, however, undergo mechanical wear as such they need frequent maintenance and replacement.
A more sophisticated fully electronic version utilizes again LF mains transformers, typically at 50 Hz or 60 Hz, connected in series between the AC input and the AC output of the voltage regulator. As the input AC voltage level varies, the AC voltage regulator electronic control senses the input voltage level, and then sets up an in-phase positive or an in-phase negative differential AC voltage that adds or subtracts, to or from, the varying input AC voltage to maintain the output AC voltage to the desired set level. This traditional approach, in its various forms, still uses LF mains frequency transformers or LF magnetic structures, typically at 50 Hz or 60 Hz. In one configuration, the power electronics generates a LF mains frequency to correct the input AC voltage by a high frequency pulse width modulation (HF PWM) means, and this in-phase correction voltage to adjust the input AC mains voltage, is applied to the primary of the LF transformer, with the secondary of the LF transformer connected in series between the input and output of the AC power line. But still the magnetic structures used in these configurations, even though the power electronics operate at higher PWM frequencies, the final differential AC waveform is still applied to the LF series transformer, typically at 50 Hz or 60 Hz, hence the LF transformer or magnetic structures still have the disadvantage of size and weight.
A series AC voltage regulation method is disclosed in U.S. Pat. No. 5,747,972. This patent discloses a particular method of using only a simple voltage polarity control, which is a limited and simple method of control. It further describes the limit of the control switching states of power semiconductor devices that is created by only using the simple voltage polarity control method at the low AC input voltage positive and negative levels around the zero voltage crossover points. To solve this problem using only simple voltage polarity control method in this indeterminate low positive or negative input voltage level range around the zero voltage crossover points leads to an ambiguous determination of the actual input voltage polarity because of the low zero crossing AC input voltages, and hence the status of the PWM switching sequence of the power semiconductors at these low positive or negative voltage levels of the AC input voltage zero crossover points. The '972 patent discloses this input AC voltage polarity indeterminate low voltage level state at below 4 volts, positive and negative—13.65, 14.5 and again 17.65, 18.5, 18.10. Accordingly, an abnormal switching sequence is generated by turning on, for a short period (e.g. 13.65 microseconds as disclosed), all of the power semiconductor switching devices. This creates a power semiconductor "shoot-through" that short circuits the input AC power source, which can cause degrading or destructive damage of the semiconductor power devices. "Shoot-through" is a term very clearly understood in the electronics industry as a very serious condition that must be avoided for power semiconductors, and engineers are always critically concerned about "shoot-through" because of its degrading and destructive impact on the power semiconductors.
It is clearly taught in the '972 patent about the aforesaid problem but seemingly rely on the actual low AC input voltage at the points of positive and negative AC input voltage near zero crossover, and also the high voltage characteristics of power semiconductor conducting voltages. The '972 patent teaches to create a deliberate shoot-through PWM switching sequence status (13.65, 14.5, and 17.65, 18.5, 18.10). Thus, because of the limitation of using AC input voltage polarity control, the '972 patent attempts to solve this problem by actually generating a deliberate "shoot-through" state of the power semiconductor switching devices that actually short circuits the AC input voltage source. This is a critical compromise, and especially in the case with modern power semiconductor devices which have much lower on-resistance and depend on the low source resistance of the AC input power supply or circuit capacitance near the semiconductor power switches. Furthermore, a "shoot-through" can also create an undefined uncontrolled current steering in the power inductor that negatively impacts operating performance. Therefore, the series AC voltage regulation method as disclosed in U.S. Pat. No. 5,747,972 has serious shortcomings.

High frequency series AC voltage regulator


A karaoke music piece is selected through a music-piece selecting section 2, and a rhythm for the performance of the karaoke music piece is designated through a rhythm designating section 5. A performance section 6 reads a melody system track of the selected karaoke music piece, and supplies the performance data to a tone generator 8. On the other hand, a rhythm pattern producing section 7 produces a rhythm performance data for the designated rhythm based on a chord and a beat at that time, and supplies the produced data to the tone generator 8. Accordingly, the selected karaoke music piece can be played with the designated rhythm which is different from the original one.

1. Field of the Invention
The invention relates to a karaoke apparatus which can play an existing karaoke music piece in such a manner that a performance formation such as a rhythm of the karaoke music piece can be changed in accordance with a preference of the user.
2. Related Art
A music-piece data for karaoke performance which is supplied to a karaoke apparatus is configured by a number of performance data tracks in order to generate various kinds of accompanying tones such as chords and rhythms. The karaoke apparatus reads the music-piece data and then transmits the data to a tone generator, so that a karaoke performance can be executed. So far as the karaoke apparatus executes a karaoke performance based on the same music-piece data, the karaoke performance of the same formation is given.
If the user of a karaoke apparatus always sings a song with the same performance, the user may be bored. Consequently, the user may sometimes wish the same music piece to be performed in a different performance formation. As described above, however, a karaoke apparatus of the prior art has a disadvantage that, so far as a karaoke performance is executed based on the same music-piece data, the karaoke performance of the same formation is given. Moreover, the preparation of music-piece data of a plurality of formations for one karaoke music piece requires much expense in time and effort, and greatly increases the amount of the music-piece data to be stored into the karaoke apparatus. Thus, such preparation is not practial.

Karaoke apparatus with alternative rhythm pattern designations