A method for obtaining substantially pure fixed oil(s), oleoresin and dietary fiber from Fenugreek seeds is provided. The method employs two different solvent extraction stages, wherein the first extraction isolates fixed oils and the second extraction isolates oleoresin. The dietary fiber remaining after extraction is clean, approximately light yellow to light brown, substantially tasteless and substantially odorless. An extraction system (23) for conducting the extractions is also provided. The extraction system (23) includes a condenser (24), a seed holding extraction vessel (25), a reboiler ((26), solvent and extract reservoir) and a feedback loop (28). The extraction solvent is obtained from the reboiler and it is contacted with the Fenugreek seeds while hot shortly after condensation in the condenser. The extraction system employs minimal amounts of solvent compared to conventional processes. In terms of color, taste, and/or odor, the food grade isolated fixed oils, oleoresin and dietary fiber are superior to those products obtained from conventional extraction processes.

This invention relates generally to a process for extraction of seeds and specifically to a process for the preparation of useful materials such as dietary fiber, oleoresin and fixed oils from the seeds of Fenugreek (Trigonella Foenum Graecum L). This invention also relates to an extraction apparatus for extraction of the seeds.
Fenugreek is an herbaceous plant of the leguminous family and is native to Western Asia, from where it has spread widely over Europe, the Mediterranean and rest of Asia. It is one of the oldest cultivated plants and through the ages has found wide application as a food, a food additive and in the traditional medicine of every region in which it has been cultivated. For example, one of its earliest uses was in Egypt where it was used as a flavoring agent in bread and other foods and as an anti-pyretic. Similarly, in India and elsewhere, the leaves, and both the ripe and unripe seeds of Fenugreek are used as vegetables and the ripe seed further, has numerous applications in the traditional medicine system of India. The seeds also function as a preservative and are added to pickles, chutneys and other similar products. In modem food practice, the seeds or the extract are used in bakery products, frozen dairy products, meat products, relish, condiments, candy, gravy sauces, gelatin puddings and in alcoholic and non-alcoholic beverages. The leaves of Fenugreek are also used in forage for cattle and the seeds as an additive in cattle feeds. Because of its significant nutrition potential, the seeds and products made therefrom are also used as food supplements.
Fenugreek has been used in treating colic flatulence, dysentery, diarrhea, dyspepsia with loss of appetite, chronic cough, dropsy, enlargement of liver and spleen, rickets, gout and diabetes. The seed is stated to be a tonic. It is also used in post-natal cure and to increase lactation in nursing mothers. Its lactation inducing property is also used with milch cattle to increase the yield of milk. The seed was used as a cure for baldness in the middle ages and today it is used as part of hair tonics in some countries. The seed also has several applications in veterinary medicine.
Modem medicine is beginning to provide confirmation of many of the traditional medicinal applications of Fenugreek. For example, it has been established that the saponins of Fenugreek and also the galactomannans contained in the mucilage of fenugreek have a beneficial effect on glucose, insulin and cholesterol metabolism.
Thus, these components along with the dietary fiber contained in fenugreek have an important role in the treatment and management of several disorders such as obesity, coronary heart disease, diabetes, piles, fissures, chronic constipation and diverticulitis. Similarly, the fixed oils of fenugreek are reported to contain the principle that causes increased lactation. The saponins mentioned above are also reported to contain active components that are anti-carcinogenic, anti-microbial and/or anti-oxidant. The saponins further contain a compound, a sapogenin called diosgeninxe2x80x94estrogen, that is the precursor in the manufacture of sexual hormones and oral contraceptives.
Fenugreek seed contains a large number of individual compounds such as volatile oil, fixed oils, proteins, carbohydrates, resins, pigments, vitamins, minerals and others. Typical analyses of fenugreek seed are shown in the tables below.
The essential oil is conventionally obtained by steam distillation of the dried seed. Steam distillation does not extract the taste factors of Fenugreek as these are fairly non-volatile resinous compounds. Thus, when incorporated in foods, the essential oil isolated by prior art methods merely provides the odor of fenugreek and not the pungent taste of Fenugreek.
The oleoresin has been obtained by extraction with an organic solvent. However, in the conventional processes, traces of the solvent remain and tend to interfere with the aroma and taste of the oleoresin. Further, conventional processes employ solvents such as chlorinated solvents, e.g, ethylene dichloride and methylene dichloride, which are toxic and pose health threats. Chlorinated solvents potentially undergo decomposition when heated to form hydrogen chloride and carbonyl chloride, which by-products are toxic. Food regulations of most countries, however, dictate that these even trace amounts of these toxic solvents be removed. Removal of the solvent traces is extremely difficult. Removal is often effected by evaporation of the solvent traces under heat and/or vacuum. However, this invariably results in a degree of damage to the heat labile flavor components and the consequent change of the oleoresins"" flavor. Other methods of removing the solvent have been developed; however, all those methods are costly, cumbersome and not always fully successfiil. The conventional production of oleoresin that is substantially true to the aroma and taste of the seed is an extremely difficult operation requiring skill and care at each stage of processing. Moreover, conventional processes are extremely unreliable due to significant variability in the quality of the isolated oleoresin.
The bitterness present in conventional extracts of Fenugreek typically comes from the hydrolytic breakdown of lipids present in the fixed oil fraction. This problem exists predominantly in conventional processes that employ steam or water extraction of components from Fenugreek seeds. The hydrolysis of lipids, which occurs over a period of time leads to rancidity and imparts a dark brown to black color to the seed. Therefore, the bitterness and darkened coloration is passed on to the residual dietary fiber of fenugreek even after the extraction. A dietary fiber product having such bitterness and coloration is not acceptable as a food product, supplement or additive.
Because of its inertness, the importance of dietary fiber was not realized until the link between fiber deficiency and several disorders and diseases was conclusively established. Modern diets, particularly the urban ones, include a large amount of processed foods that are carbohydrate rich and fiber deficient. Fiber deficiency is now known to be the causative factor of several disorders, such as heart ailments and coronary artery disease, diabetes, constipation, colon cancer, piles, fissures, gallstones and others. A diet having adequate amount of dietary fiber is now known to be important not only from the point of view of preventing the disorders but also in the cure and management thereof. Public health and Nutrition bodies now prescribe a minimum daily dietary fiber intake and the recommended figures range between 30 to 40 gm per day per person. For individuals having fiber related disorders, dietary fiber offers either a cure or help in the management thereof. It has been reported that high sugar and fat rich foods, i.e., fiber depleted foods, form 55 to 60% of the daily calorie intake in many countries as compared to 15-20% a century ago.
Insoluble dietary fiber mainly comprises cellulose, lignins and some hemicelluloses; while, soluble dietary fiber mainly comprises pectin, gums and some hemicelluloses. The two types play somewhat different roles in the intestinal tract. The former enhances the food bulk and generates a feeling of satiety although the feeling is not as strongly perceived as in the case of the latter. Increased satiety leads to lower food intake. Insoluble fiber also causes increase in faecal bulk by virtue of its indigestible nature and because of fermentation thereof, in the intestine. The insoluble fiber causes quicker movement of the food mass along the intestinal tract. Soluble fiber on the other hand, tends to enhance the viscosity of the food mass in the intestinal tract and slows down the transit down the tract thereof. The feeling of satiety is also observed with diets incorporating soluble fibers and as mentioned the feeling is stronger than for insoluble fibers. The food intake therefore, tends to go down also with soluble fibers. Soluble fiber also undergoes fermentation in the gut producing some volatile fatty acids which are important from the point of view of nutrition. These fatty acids are absorbed by the intestine.
Soluble fiber of Fenugreek, guar gum, oat bran, oat gum, oat hulls, bengal gram and pectin have a strong cholesterol lowering effect. Similar lowering has also been observed in the case of serum triglycerides/triacylglycerols. HDL and LDL cholesterol are also favorably affected and an improvement of the HDL/LDL ratio is observed with soluble fiber. The beneficial effect also extends to liver cholesterol and triglycerides.
The groups of above compounds that are of significance commercially (and industrially) include essential oil, fixed oils, oleoresin and dietary fiber. These are generally obtained by fractionation of Fenugreek using one or more processes such as steam distillation, hydro-extraction, solvent extraction, hydrolysis and others. These conventional processes, however, generally do not provide acceptable products or are limited to providing only one useful product obtained from Fenugreek.
One extraction process requires that the solid material be charged into a vessel (tank) and fresh extraction solvent added thereto. Enough solvent is added, i.e., generally up to a level of few centimeters above the solids level, to ensure complete submergence of the solid material. Such an extraction system is referred to herein as a static system and the solid material being extracted as a xe2x80x9cbed of solidsxe2x80x9d or xe2x80x9csolid bedxe2x80x9d. Where extraction is required to be conducted at a temperature above ambient, the vessel is optionally provided with a jacket for circulation of a heating medium such as steam, hot water or others. At the end of extraction, the extract and the extracted solids are removed from the vessel. The extraction solvent is drained from the vessel either intermittently or continuously by way of a false bottom comprising a perforated plate and/or a filtration medium. The chief drawback of a conventional static system that employs the addition of unheated fresh solvent is the difficulty of maintaining a uniform temperature in the bed particularly when heat is added, by heating coils, into the vessel contents. The temperature is found to be neither uniform throughout the bed nor over the period of extraction. Such nonuniformities in temperature and solvent concentration render the extraction process somewhat non-reproducible in that small but subtle differences in the composition and quality of the extract are observed from batch to batch. For example, in conventional static extraction process, the moisture content present in the seed passes into the extraction solvent at the commencement of the extraction. Thus, during the rest of the extraction, the solvent in contact with the seeds is somewhat diluted by that moisture resulting in a lower driving force for extraction.
When fresh, i.e., solute-free, solvent is contacted with solids to be extracted the driving force for extraction (for dissolution of solute in solvent) is high. However, the driving force continually diminishes as extraction proceeds. Actually, a point is reached where the rate of extraction is so diminished that further extraction is uneconomical. Generally, the extract is then drained out and a new batch of solvent added to the bed to continue the extraction. The new batch of solvent may be either fresh (solute free) solvent or a dilute extract from another extraction batch, e.g., countercurrent extraction method. In another embodiment of the static system the solvent containing extracted solute is continuously circulated to improve contact of the solvent and solids; however, this reduces extraction efficiency due to the extraction solvent already containing solute.
Conventional static systems have the same drawback of nonuniformities. In a static system with the continuous solvent re-circulation, channeling of the solvent in the bed also causes the nonuniformities. A further disadvantage is that a continuous circulation system requires a larger amount of solvent, which adds to the costs of solvent recovery by evaporation or other means. Also, a solvent re-circulation system that recycles used solvent requires additional capital equipment in the form of additional solvent pumps, tanks and other items. Another drawback of conventional static systems is that the contact between the solvent and solid is not efficient. Thus even if the driving force is high, for example as at commencement of extraction, the actual rate of solute dissolution remains low.
One approach to the problem of low dissolution rates in the prior art is to employ a stirred/agitated tank reactor in which the solvent and solid are contacted. Such a system is referred to herein as a dynamic system. A dynamic system can be adapted to the continuous or intermittent solvent re-circulation and also to the counter current arrangement. A dynamic system undoubtedly provides better solventxe2x80x94solid contact but has the drawback of a greater capital investment. Also, it requires a larger amount of solvent leading to increased capital costs and increased operating costs in solvent evaporation or removal and recovery.
Processes for the extraction of Fenugreek are disclosed in U.S. Pat. No. 5,658,571 to Gopalan et al., U.S. Pat. No. 5,997,877 to Chang, U.S. Pat. No. 6,013,289 to Blank et al., and U.S. Pat. No. 6,013,304 to Todd. However, none of these references disclose the presently claimed extraction process and associated process equipment.
The process of Gopalan et al. is a static type process and consequently suffers from the drawback of the nonuniformities discussed above. Gopalan et al. disclose the use of a single solvent that apparently extracts a mixture of fenugreek fractions. Gopalan et al. do not disclose recovery of the individual Fenugreek fractions by selective sequential solvent extraction with different solvents. Gopalan et al. also disclose that the extraction solvent is heated after the Fenugreek seed is immersed in the solvent. Moreover, most of the solvents used by Gopalan et al., with the exception of ethanol and isopropanol, are either chlorinated or toxic or both, and therefore somewhat unsuitable for applications involving food grade products. Gopalan et al. also disclose multiple extractions, each with a separate batch of fresh solvent or each with solvent containing extracted solutes. In neither embodiment do Gopalan et al. add a heated solvent to the Fenugreek seeds. In addition, Gopalan et al. do not disclose repeatedly contacting the Fenugreek seeds with freshly distilled hot recirculated solvent obtained from a reservoir containing the extraction solvent comprising solute.
The process of Chang is a dynamic type process, which also suffers from the associated disadvantage/drawbacks outlined above. The Chang process produces oleoresin wherein the fixed oils therein have not been removed. Therefore, the oleoresin product is susceptible to bitterization and discoloration caused by rancidity in the fixed oils. The Chang process introduces water into the system by tempering the seeds prior to extraction and by the use of 95% ethanol in the extraction process even before the removal of the bulk of fixed oils therein.
Accordingly, the known processes for extracting components from Fenugreek provide unacceptable products in terms of excessive colorization, bitterness, and rancidity. None of the known art discloses a process for separating fixed oil and then oleoresin from Fenugreek seeds to obtain a dietary fiber rich meal.
The present invention addresses the problems and drawbacks associated with conventional processes for obtaining useful products from Fenugreek seeds. In particular, low boiling non-toxic solvents have been selected where the removal of trace amounts of solvent from the useful products is comparatively easy. One of the highlights of the process of the invention is that the process of extraction of oleoresin, although highly simple and economical, reproducibly provides a high purity food grade product oleoresin by minimizing contact temperature nonuniformities inherent in conventional processes. By continuously providing freshly distilled recycled hot solvent, the present process is cost effective, provides maximum extraction efficiency, and balances the contact ratio and contact time to provide an overall economical process in terms of operating and capital costs. Contact of seeds with water during extraction is eliminated by avoiding contact of the seeds with water at least until the bulk of the fixed oils have been extracted out of the seeds by the first extraction solvent. The process of the invention can be used to provide a dietary fiber having a fat content of less than about 0.5% or less than about 0.3%.
The process of the invention employs a 2-stage extraction process in which two separate solvents are used, the pair of solvents being selected such that the first solvent extracts the fixed oils exclusively, or almost exclusively, and the second solvent extracts the oleoresin and optionally other components present in the Fenugreek seeds. The second solvent extracts out substantially all of the remaining fixed oils in the seed, thereby reducing the lipid content remaining in the residual dietary fiber generally to below 0.5%, below 0.3%, or below 0.1%.
A key feature of the present invention is that the fixed oils of the seed are isolated and removed as a first step so as to ensure a dietary fiber having little to no bitterness or discoloration. The second fraction obtained by solvent extraction of the seed from which the fixed oils have been removed is quite faithful to the aroma and taste of fenugreek. The second fraction therefore referred to herein and in the art as the oleoresin, despite the fixed oils having been separated therefrom. By removing a major portion of the fixed oils from the seeds with the first extraction solvent, the present process eliminates or reduces the occurrence of bitterness and excessive coloration of products obtained by subsequent processing of the seeds.
This invention provides a process for the isolation of essential oil, oleoresin, fixed oil, proteins, vitamins minerals, saponins, and/or sapogenins from Fenugreek seeds. These products are obtained by fractional separation of some of these fractions of Fenugreek seed. The invention provides a process for the production of substantially pure food grade dietary fiber, oleoresin and fixed oils from Fenugreek seeds.
The process of the invention comprises the following general features: 1) a two-stage process employing two different solvents having solubility characterisitics such that the first solvent selectively extracts out the bulk of its fixed oil fraction of the seeds during the first stage and the second solvent is effective in extracting out substantially all of the oleoresin fraction and substantially all of the small amount of fixed oils remaining in the first extracted mass; 2) contact of solids with freshly condensed solvent in both stages such that the bed is substantially continuously charged with the freshly condensed solute-free solvent thereby maximizing extraction efficiency; 3) draining of the solvent in contact with the bed of seeds each time the bed is completely submerged by the solvent such that the bed is substantially continuously in contact with freshly condensed solute free solvent and the extraction rate is maximized throughout the extraction, the contact being substantially at the highest feasible temperature, which is generally the condensing temperature of the solvent; 4) addition of hot freshly condensed solvent to the bed of seeds such that the process conserves heat, is simplified and requires very simplified extractor equipment; 5) evaporation of the extraction solvent from the first extract yields a substantially pure fixed oil fraction generally requiring no further separation and purification; 6) evaporation of the extraction solvents from the extracted fractions is not an added cost as the process is based on continuous evaporation and condensation of solvents; 7) the pair of extraction solvents employed in the process are low-boiling, non-toxic and non-hazardous from health point of view and traces thereof are easy to remove/recover; and 8) the extraction of the major portion (generally at least about 85%) of the fixed oils fraction during the first extraction stage thereby allowing the use of even aqueous alcohol solvents during the second extraction stage while minimizing the risk of bitterisation and discoloration (excessive coloration), the advantage of use of the aqueous alcohol solvents during the second extraction stage being that it rapidly and effectively extracts out the oleoresin and the remainder of fixed oils from the seeds; 9) a simple, novel, cost-effective procedure for separation of the oleoresin and fixed oils from the second extract; and 10) potential for the use of solvent mixtures.
According to one aspect of the invention there is provided a process for the extraction of Fenugreek (Trigonella Foenum Graecum L.) seeds to produce substantially pure dietary fiber, oleoresin and fixed oils comprising the steps of:
1) optionally, sorting and cleaning Fenugreek seeds and crushing, grinding, flaking and/or milling thereof;
2) extracting the seeds with a hot substantially freshly condensed first solvent (or mixture of solvents) in a first stage of extraction to yield a first extract and partly extracted seeds;
3) extracting the partly extracted seeds with a hot substantially freshly condensed second solvent (or mixture of solvents) in a second stage of extraction to yield a second extract and a wet dietary fiber; and
4) drying of the wet dietary fiber to form a substantially pure dietary fiber.
The process of the invention can also include one or more of the following steps:
heating the first extract to evaporate the first solvent therefrom to yield substantially pure fixed oils;
heating the second extract to evaporate the second solvent therefrom to yield a product mixture of oleoresin and fixed oils;
treating the product mixture with ethanol for a period of time and at a controlled temperature to form a treated mixture;
cooling the treated mixture to yield a liquid comprising a heavy phase and a light phase;
separating the heavy and light phases, wherein the heavy phase comprises the substantially pure oleoresin;
separating, by filtering or other means, any solids or crystallized impurities, such as fats and waxes, from the light phase; and
evaporating ethanol from the light phase to yield the substantially pure fixed oils.
The invention also provides a method of obtaining valuable components from Fenugreek seeds comprising the steps of:
extracting the Fenugreek seeds with a first extraction solvent to provide a first useful extract and a first extracted mass;
extracting the first extracted mass with a different second extraction solvent to provide a second useful extract and a second extracted mass; and
removing solvent from the second extracted mass to provide a useful solid.
Specific embodiments of this aspect of the invention include those wherein: 1) the first extraction solvent is petroleum ether and the second extraction solvent is 90-5% ethanol (aq.); 2) the first useful extract comprises fixed oils and the second useful extract comprises oleoresin; 3) the first solvent is selected from the group consisting of petroleum ether, hexane, n-propanol, isopropanol, and a combination thereof; 4) the second solvent is selected from the group consisting of ethanol, isopropanol, aqueous isopropanol, aqueous ethanol and a combination thereof; 5) a major portion of the first extraction solvent is removed from the first useful extract to form substantially pure fixed oil; 6) a major portion of the second extraction solvent is removed from the second useful extract to form a mixture comprising oleoresin and optionally fixed oil; 7) the mixture of oleoresin and fixed oil is treated with an ethanolic solution to form substantially pure oleoresin and a mixture of other components including fixed oil; 8) solids are removed from the mixture of other components and fixed oil and the ethanol and water are evaporated to form substantially pure fixed oil; 9) the useful solid comprises a dietary fiber; and/or 10) the seeds are cleaned, ground, sorted, tempered, flaked, crushed and/or milled prior to extraction.
According to other aspects of the invention, there is provided a dietary fiber, fixed oil or oleoresin of fenugreek seed produced by the process of the invention optionally conducted in the extraction system of the invention.
Accordingly, the invention also provides a substantially pure fixed oil obtained from Fenugreek seeds by a process comprising the steps of:
substantially continuously contacting a freshly condensed hot first extraction solvent with a bed of Fenugreek seeds for a period of time and at a constant temperature sufficient to form an extract comprising fixed oil and the first extraction solvent, wherein the freshly condensed first extraction solvent is obtained from a reservoir containing the extract;
separating the Fenugreek seeds from the extract; and
removing at least a major portion of the extraction solvent from the extract to form the fixed oil.
Specific embodiments of the invention include those wherein: 1) the first extraction solvent is selected from the group consisting of petroleum ether, hexane, n-propanol, isopropanol, and a combination thereof; 2) the temperature of the extraction solvent approximates the boiling point or the condensation temperature of the first extraction solvent; 3) wherein the fixed oil comprises fatty acid esters such as the glycerol esters of palmitic, arachidic acid, behenic, oleic, linoleic and/or linolenic acid; 4) the ratio of the Fenugreek seeds to the first extraction solvent from about 1:1 to 1:5 weight/volume (kg/L).
The invention also provides a substantially pure oleoresin obtained from Fenugreek seeds by a process comprising the steps of:
contacting Fenugreek seeds with a first extraction solvent for a period of time and at a temperature sufficient to form a first extract comprising fixed oil and the first extraction solvent, wherein a major portion of fixed oil present in the Fenugreek seed is removed by the first extraction solvent;
separating the Fenugreek seeds from the first extract to form partially extracted seeds;
contacting the partially extracted seeds with a different second extraction solvent for a period of time and at a temperature sufficient to form extracted seeds and a second extract comprising oleoresin, fixed oil and the second extraction solvent;
separating the extracted seeds from the second extract;
removing at least a major portion of the second extraction solvent from the second extract to form a concentrate;
contacting the concentrate with an ethanolic solution to form a heterogeneous solution comprising an oleoresin-containing layer and one or more other layers; and
isolating the oleoresin-containing layer to form a substantially pure oleoresin.
Specific embodiments of this aspect of the invention include those wherein: 1) the Fenugreek seeds are contacted with the first extraction solvent continuously, semi-continuously or batchwise; 2) the first and/or second extraction solvents are percolated through the Fenugreek seeds; 3) the first and/or second extraction solvents are freshly distilled; 4) the first extraction solvent is obtained from a reservoir comprising fixed oil and the first extraction solvent; 5) the second extraction solvent is obtained from a reservoir comprising oleoresin, second extraction solvent and optionally fixed oil; and/or 6) the ethanolic solution comprises ethanol or ethanol and water.
The invention further provides a dietary fiber obtained after extraction of Fenugreek seeds by an extraction process comprising the steps of:
extracting the Fenugreek seeds with a first extraction solvent to remove fixed oil from the seeds;
extracting the partly extracted seeds with a different second extraction solvent to remove oleoresin from the seeds; and
separating the seeds from any remaining extraction solvent to form a dietary fiber.
Specific embodiments of this aspect of the invention include those wherein: 1) the solvent temperature approximates the boiling point or the condensation temperature of the respective extraction solvent; 2) the first and second solvents are hot and freshly condensed when used to extract the Fenugreek seeds; 3) at least a major portion of fixed oils are removed from the dietary fiber by extraction; 4) wherein at least a major portion of oleoresin are removed from the dietary fiber by extraction: 5) the dietary fiber has little to no taste, is light yellow to light brown, and has little to no odor; 6) the dietary fiber has a fat content of less than 0.5%, less than 0.3% or less than 0.1%; and/or 7) the dietary comprises approximately equal amounts of soluble fiber and insoluble fiber.
The invention thus provides a method or process for making substantially pure food grade dietary fiber from fenugreek seeds and to recover two other fractions thereof, namely, oleoresin and fixed oils also in substantially pure form and of food grade quality. The invention also provides substantially pure food grade dietary fiber, oleoresin and fixed oils, wherein de-bitterisation of the dietary fiber is also achieved.
According to another aspect of the invention, there is provided an extraction system for the extraction of fenugreek seeds comprising:
an extraction vessel having means for holding the bed of solid materials to be extracted;
a reboiler;
a condenser; and
conduits interconnecting the condenser and the reboiler so as to conduct vaporized solvent from the reboiler to the condenser.
The condenser effects condensation of the solvent vapors to form a freshly distilled hot solvent that is contacted with the bed at substantially the condensing temperature thereof. The system also comprises means for periodically draining the extracts from the reboiler, means for controlling heat input to the reboiler, cooling means in the condenser, and other control means as needed.
Other aspects of the invention provide finished products comprising the above-described fixed oil, oleoresin or dietary fiber. Some embodiments of this aspect include: 1) omega fatty acids derived from the fixed oils of fenugreek; 2) essential oil of fenugreek; 3) resinous taste compound(s); 4) flavoring compound(s); 5) galactomannans; 6) protein; 7) amino acids such as lysine; 8) insoluble fiber; 9) soluble fiber; 10) vitamin(s); 11) mineral(s), such as sodium, potassium, iron and phosphorous; 12) choline; and/or 13) carbohydrates. These products can be used in vitamin supplements, nutritional supplements, dietary supplements, and/or as food additives.
Thus, the invention provides a fenugreek-based dietary fiber that can be consumed as a supplement or added to other food during the process of cooking thereof. In addition, other nutrients may be added to the dietary fiber of the invention to provide a greater nutritional balance and/or to restore nutritional deficiencies. A dietary fiber product may also comprise added taste, flavor and/or coloring agents.

Process for obtaining useful materials from Fenugreek seeds

43/52 Dr. Jagannatha Nagar, Aerodrome Post

Kalyani Chemical Campus, Mettur Main Rd., Near Bus Stand


In a lap winding apparatus for producing a batt lap, the batt is wound onto a tube which is rotatable about a fixed axis and is driven by a revolving endless belt. The belt is arranged in a loop, formed between two deflecting rolls and is tensioned by a tensioning device. The tube which is rotatable about a fixed axis, as well as the two deflecting rolls are dimensioned, and positioned relative to each other, in such a manner that the loop at the beginning of the lap winding process embraces the tube over an initial minimum wrapping angle equal to, or larger than, 120xc2x0 and preferentially equal to, or larger than, 180xc2x0. For generating a tensioning force depending on the lap diameter, the tensioning device is associated with a control device.

The present invention concerns a lap winding apparatus for producing a in which a batt is wound onto a core which is rotatable about a fixed axle.
In a lap winding apparatus is known from GB 329 871 in which an endless belt is driven over two deflecting rolls and the core to form a loop that is tensioned by a tensioning arrangement. The belt, at the beginning of the lap winding process, contacts a small portion of the core circumference. The wrapping angle is less than 600. Tensioning of the belt is effected by means of an angled lever at one arm of which a deflecting roll embraced by the belt is provided and at the other arm of which a weight is provided which for setting the tensioning force can be adjusted manually.
In this known lap winding apparatus, a kind of pulling effect can occur due to the local strain affecting the baft, which causes the lap layers to be shifted against each other. Due to the friction, felting of the baft can occur, which causes problems, impairing product quality, as the lap unrolls.
It thus is the goal of the present invention to create a lap winding apparatus of the above mentioned type which is simple in lay-out and which permits production of high quality taps which can be unrolled without problem.
This goal according to the invention is achieved in that the core is rotatable about a fixed axis and the two deflecting rolls are dimensioned and positioned in such a manner that the belt loop at the beginning of the lap winding process embraces the core over an initial minimum wrapping angle of 120xc2x0 or larger and preferably of 180xc2x0 or larger and that the tensioning device for generating a tensioning force depending on the lap diameter is associated with a control device.
Since the rotatable core is, at the beginning of the lap winding process being surrounded over a large area by the belt, i.e. over a larger wrapping angle, the lap being formed from the beginning is put under a much more even pressure. Furthermore any possible formation of an oval shape of the lap can be effectively counteracted by correspondingly adapting the tensioning force to the current lap diameter. The fixed axis of the core notwithstanding, occurrence of a pulling effect can be virtually excluded. In this arrangement, shifting of the batt layers against each other and felting of the batt is prevented. Thus, a high quality lap is produced which can be unrolled without problems in subsequent processing of the baft.
Particularly in view of negligible formation of blisters and of further improved unrolling properties, it proves advantageous if the tensioning device is controlled by the control device in such a manner that the tensioning force diminishes as the lap diameter increases until a pre-determinable lap size is reached. In this process the tensioning force preferentially diminishes linearly as the lap diameter increases until a pre-determinable lap size is reached. Owing to the harder pressure applied in lap winding during the beginning stages, plasticity of the of the lap is reduced and the lap gains more stability in itself which positively influences the unrolling properties as well as the quality.
A further advantage is gained if the pre-determinable lap size is chosen smaller than the final lap size and if the tensioning force is maintained constant until the pre-determinable lap size is reached. In this process, it is provided preferentially that while the lap diameter increases, the tensioning force is reduced over the major part of the lap winding process and that only towards the end of the lap winding process is maintained constant at a value above zero until the final lap size is reached.
The control device, which preferentially is an electronic control device, can be associated with a sensor which scans the lap diameter directly. In principle it also is possible to provide a measuring device which monitors the baft length fed to the lap winding apparatus in order to obtain a signal representative of the lap diameter for the control device.
In a preferred embodiment of the present invention, the tensioning device comprises a tensioning roll associated with a linear guide arrangement. In this arrangement, the belt is tensioned in a plane parallel to the plane containing the axes of the two deflecting rolls between which the belt loop forms. Particularly, if control of the tensioning force is to be effected as precisely as possible,. it also proves advantageous if the belt embraces the tensioning roll, independently of the position of the latter, always over a wrapping angle of 180xc2x0. In this case, the two belt sections facing each other extend mutually parallel in the area of the tensioning roll, which permits, among other advantages, more precision in the control of the tensioning force. Adjustment of the position of the tensioning roll can be effected using an electric, hydraulic or pneumatic drive associated with the control device, the drive appropriately comprising a cylinder/piston unit.
The belt expediently is driven via at least one of the deflecting rolls. For controlling the belt drive speed in an open loop or closed loop control system, the belt drive can be associated with the control device. The belt drive speed can be varied in function of the lap diameter and can e.g. decrease as the lap diameter increases. The open or closed loop control system can be laid out in such a manner that the belt drive speed at the beginning of any lap winding process is increased from zero to a predetermined value. The belt drive can be frequency controlled using an invertor or similar devices. It also can be imagined that the belt drive speed be maintained constant at least temporarily.
If the core is formed by a tube, this tube can be placed e.g. on an extension each on the two lap disks facing each other between which the tube preferentially is clamped.
The two deflecting rolls, between which the belt loop forms, for ejecting the lap can be preferentially moved apart relative to each other while simultaneously the belt is tensioned.
According to a particularly advantageous embodiment of the invention removal of at least one of the lap discs, effected e.g. by extending, traversing or similar movements, ejection of the lap, transfer of the lap to a transporting device or similar steps and/or inserting and clamping of a new empty tube is automated at least partially and again is controlled by means of the control device.
In order to avoid electrostatic charges, the belt is made of a Kevlar material.
The lap winding apparatus is applicable in particular in combing where a baft or web e.g. delivered by a drafting system via deflecting plates, via calendar rolls and/or via similar elements is taken up. The completed lap subsequently is fed to a combing machine.


A pixel includes an organic light emitting diode, a first driver and a second driver. The second driver controls an amount of current supplied from a first power source to the organic light emitting diode, corresponding to a previous data signal. The first driver stores a current data signal supplied from a data line and supplies the previous data signal to the second driver. In the pixel, the second driver includes a sixth transistor coupled between an initialization power source and a first node coupled to a gate electrode of a first transistor, the sixth transistor being configured to turn on when a first control signal is supplied; and a seventh transistor coupled between the first power source and a second node commonly coupled to the first and second drivers, the seventh transistor being configured to turn on when the first control signal is supplied.

1. Field
Embodiments of the present invention relate to a pixel and an organic light emitting display using the same.
2. Description of the Related Art
With the recent advances in information technologies, the importance of a display as a mode of presenting information has increased. Accordingly, flat panel displays (FPDs) such as a liquid crystal display (LCD), an organic light emitting display and a plasma display panel (PDP) are being increasingly used.
An organic light emitting display displays images using organic light emitting diodes that emit light through recombination of electrons and holes. The organic light emitting display has a fast response speed and has low power consumption.

Pixel and organic light emitting display using the same


In order to provide a highly reliable silicon-germanium semiconductor optical element of high luminous efficiency or of low power consumption that can reduce or prevent the occurrence of dislocations or crystal defects on the interface between a light emitting layer or a light absorption layer and a cladding layer, in a silicon-germanium semiconductor optical element, a germanium protective layer 11 of non-light emission is disposed between a germanium light emitting layer or the light absorption layer 10 and a cladding layer 12 disposed above a substrate. The germanium protective layer 11 has the electrical conductivity different from electrical conductivity of the germanium light emitting layer or the light absorption layer 10.

Studies of optical devices and optical circuits, which are formed on a silicon substrate, more specifically on an SOI (Silicon on Insulator) substrate, are conducted actively, and a field called silicon photonics is created. Since the light emission and absorption coefficients of silicon are smaller than the light emission and absorption coefficients of III-V compound semiconductors, which are practically used, the introduction of germanium of excellent integration with silicon is zealously attempted (Patent literatures 1 and 2, for example).


A method determines a mounting condition of a mounter mounting a component onto a board, which includes the steps of: obtaining an operational sate parameter; and determining, in the case where a value of the obtained operational state parameter is not within a predetermined range, a mounting condition so that the value of the operational state parameter falls within the predetermined range.

1. Technical Field
The present invention relates to a method of determining mounting conditions of a mounter which mounts components onto a board, and in particular, to a method of determining mounting conditions which are adaptive to an individual mounter.
2. Background Art
Conventionally, both hardware and software solutions are provided in order to achieve higher throughput in a mounter which produces a component-mounted board by mounting electronic components onto a print wiring board or the like. The hardware solution aims at moving the components at a high speed in each of the following processes: a suction process of sucking and holding the components to be supplied to the board so as to pick up the components by vacuum; a transportation process of transporting the picked-up components from a component supply unit to the board; and a mounting process of lowering the transported components so as to place the components. The software solution aims to optimize mounting conditions such as an order of arranging component feeders for component supply which are equipped to the mounter, and an order of mounting the components (see reference to Japanese Laid-Open Patent Application No. 2002-50900).
In terms of hardware, tolerance of size is required in the manufacturing of the mounters, and variations in device accuracy among the individual mounters are generated due to varied manufacturing accuracies of the mounters even though the variations are within the range of the tolerance. Moreover, piece-to-piece variations in accuracy which are unique to an individual mounter such as a variation due to deterioration with age like wearing of the components making up a mounter and a variation due to change in temperature during the period from when the power is turned on until when the machine is warmed up.
Therefore, in terms of software, the mounting conditions which absorb the variations regarding hardware and guarantee a steady performance are set.
More precisely, (a) in FIG. 1 shows an ideal positional relationship between an electronic component A to be supplied and a suction nozzle 11 for sucking and holding the electronic component A. However, since there being diverse variations in the manufacturing of the mounters as mentioned above, the electronic component A may, in some cases, be supplied, misaligned with the ideal position as shown in (b) and (c) in FIG. 1. When the suction nozzle 11 attempts to suck and hold the supplied electronic component A and such misalignment occurs in the supply of the electronic component, the edge of the suction nozzle 11 is misaligned with the edge of the electronic component A.
Even in the conventional case where the edge of the suction nozzle 11 is misaligned with the edge of the electronic component A and the air leaks, as in the state shown in (b) in FIG. 1, it is still possible to directly transport the electronic component A and mount the electronic component A onto the board given that the static state is maintained for a certain period of time after the suction nozzle 11 come into contact with the electronic component A. Therefore, the variations with regard to hardware are absorbed by the software solution of setting mounting conditions which always include a static state lasting a certain period of time.
Thus, although many of the variations with regard to hardware are absorbed by the setting of the mounting conditions they are the factors that prevent the enhancement of the throughput of the mounter.
Note that the reason why the transportation and the mounting can be realized under the condition in which the static state is maintained despite of the leakage of the air is that the oscillation occurs due to the pressure within the suction nozzle 11 and the electronic component A to be sucked and held flutters immediately after the leakage, but when the static state is maintained for a certain period of time, it is possible to obtain the suction indicating a predetermined value or greater where the oscillation due to the pressure is settled down and its stability is restored. In the state as shown in (c) in FIG. 1, it is not possible to solve the problem by the software solution since the suction rate indicating a predetermined value or greater cannot be obtained even though the static state is maintained.
The present invention is conceived in view of the above-mentioned problem, and an object of the present invention is to provide the most suitable mounting conditions according to the state of an individual mounter in terms of hardware.


Gels and polymers comprising a polypeptide bound to a polysaccharide are disclosed. Specific polypeptides include, but are not limited to, polypeptides that comprise glutamine or tyrosine residues. Specific polysaccharides include, but are not limited to, chitosan. Gels and polymers of the invention can be used for the in vitro and in situ formation of protein-polysaccharide conjugates. Methods of making polypeptide/polysaccharide gels and polymers are also disclosed.

1. Field of the Invention
This invention is directed, in part, to polymers and gels comprising a polypeptide and a polysaccharide, and to methods of making the same.
2. Description of Related Art
Hydrogels are providing new opportunities for a variety of medical applications. Biomaterials Science: An Introduction to Materials in Medicine (Ratner B D et al., eds.; 1996); Okano T. Biorelated Polymers and Gels (1998). Examples include the use of hydrogels as skin substitutes, adhesives, matrices for drug delivery, and scaffolds for tissue engineering. See, e.g., Biomaterials Science: An Introduction to Materials in Medicine; Peppas N A and Sahlin J J, Biomaterials 17:1553–1561 (1996); McCulloch I and Shalaby S W, "Tailored polymeric materials for controlled delivery systems" (Washington D.C.: American Chemical Society, 1998); Dinh S M, DeNuzzio J D and Comfort A R, "Intelligent materials for controlled release" (Washington D.C.: American Chemical Society, 1999); Mallapragada S, Tracy M, Narasimhan B, Mathiowitz E and Korsmeyer R., "Biomaterials for drug delivery and tissue engineering" (Warrendale, Pa.: Materials Research Society, 2001); Lee K Y and Mooney D J, Chem. Rev. 101:1869–1879 (2001). In many of these applications it would be desirable if the hydrogel could be formed in situ. For instance, it would be possible to "implant" materials using minimally invasive methods if systems were available that could be injected as solutions and gelled only after injection. Elisseeff J, et al., Proc. Natl. Acad. Sci. 96:3104–3107 (1999). Further, in situ gel formation would allow gels to be created that filled the available space. Gutowska A, Jeong B and Jasionowski M., Anat Rec. 263:342–349 (2001); Gerentes P, et al., Biomaterials 23:1295–1302 (2002). Obviously, major constraints on such gel-forming systems are that they must be non-toxic and biocompatible.
There are a few common approaches for creating gels that could be extended to in situ systems. One approach commonly used for in vitro gel formation is to initiate polymerization reactions in the presence of multi-functional monomers. Since these multi-functional monomers are incorporated into two (or more) growing polymer chains the reaction leads to a three-dimensional network. Huang Y, Szleifer I and Peppas N A, Macromolecules 35:1373–1380 (2002). An example of this approach for in situ applications is the cyanoacrylate adhesives. Smith D C, "Adhesives and sealants," Biomaterials Science: An Introduction to Materials in Medicine p. 319–328 (Ratner B D et al., eds.; 1996). Since low molecular weight and reactive monomers are used, this approach raises concerns of toxicity and compatibility. A second approach for forming gels which is particularly attractive for in situ applications is to use "smart" polymers that gel in response to the conditions experienced after injection/application. Galaev I Y and Mattiasson B, Trends Biotechnol 17:335–340 (1999). Typical smart polymers respond to changes in temperature or pH and can be made of natural (e.g., gelatin) or synthetic (e.g., poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide))polymers. Bromberg L E and Barr D P, Macromolecules 32:3649–3657 (1999); Huibers P D T, et al., Macromolecules 32:4889–4894 (1999). This approach is attractive for in situ applications although there are currently few smart polymers that are also biocompatible. A third approach for gel formation is to initiate the crosslinking of soluble, linear polymers or macromonomers. Typically, crosslinking is initiated using light or low molecular weight crosslinking agents such as glutaraldehyde. See, e.g., Elisseeff J, et al., J. Biomed. Mater. Res. 51:164–171 (2000); Ono K, et al., J. Biomed. Mater. Res. 49:289–295 (2000); Bryant S J and Anseth K S, Biomaterials 22:619–626 (2001); Behravesh E, Jo S, Zygourakis K and Mikos A G, Biomacromolecules 3:374–381 (2002); Temenoff J S, et al., J. Biomed. Mater. Res. 59:429–437 (2002); Koh W G, Revzin A and Pishko M V, Langmuir 18:2459–2462 (2002); Mi F-L, et al., Carbohydrate Polymers 41:389–396 (2000); Bigi A, et al., Biomaterials 22:763–768 (2001). For in situ applications there are safety concerns associated with the use of such low molecular weight and reactive compounds (i.e., monomers or initiators).
In many cases, natural polymers are advocated as biomaterials because they may be non-toxic, biodegradable, and have low immunogenicities. Yannas I V, "Natural Materials," Biomaterials Science: An Introduction to Materials in Medicine p. 84–94 (Ratner B D et al., eds.; 1996). In addition to reducing or avoiding adverse effects, biopolymers may actually offer beneficial properties. For instance collagen is a major component of the extracellular matrix of tissue, and collagen (or gelatin) based materials are reported to promote cell attachment and growth. Koide M, et al., J. Biomed. Mater. Res. 27:79–87 (1993); Stanton J S, et al., J. Mater. Sci.-Mater. Med. 6:739–744 (1995). Chitosan has also been reported to have antimicrobial hemostatic, and wound healing properties that could be exploited for biomaterials. Muzzarelli R, et al., Antimicrob. Agents Chemother. 34:2019–2023 (1990); Mi F L, et al., Biomaterials 22:165–173 (2001); Mi F, et al., J. Biomed. Mater. Res. 59:438–449 (2002); Rao S B and Sharma C P, J. Biomed. Mater. Res. 34:21–28 (1997); Ishihara M, et al., Biomaterials 23:833–840 (2002); Muzzarelli R, et al., Biomaterials 9:247–252 (1988); Ueno H, et al., Biomaterials 20:1407–1414 (1999); Cho Y W, et al., Biomaterials 20:2139–2145 (1999).
Apart from having the desirable chemical and biological properties, biomaterials must have the mechanical properties (e.g., strength, hardness and durability) required by whatever applications they are used in. Anseth K, et al., Biomaterials 17:1647–1657 (1996). The mechanical properties of tissue are often conferred by protein-polysaccharide conjugates (e.g., proteoglycans and mucins), and there has been considerable recent interest in generating such conjugates for various applications, especially as dressings and scaffolds for tissue engineering. See, e.g., Yannas I V, et al., Proc. Natl. Acad. Sci. USA 86:933–937 (1989); Yannas I V and Burke J F, J. Biomed. Mater. Res. 14:65–81 (1980); Choi Y S, et al., J. Biomed. Mater. Res. 48:631–639 (1999); Angele P, et al., Tissue Eng. 5:545–554 (1999). Unfortunately, the complexity of protein-polysaccharide conjugates has made it difficult to recover or synthesize these glycoconjugates.

Polysaccharide-based polymers and methods of making the same

University of Maryland, Baltimore County

University of Maryland Biotechnology Institute

The United States of America as represented by the Secretary of the Agriculture


A method, computer apparatus and computer program product are provided for autonomously transporting an asset along a track to a destination in a manner that is safe, reliable and quick. In regards to the method, instructions are received relating to the shipment of the asset to the destination. Based upon the instructions, a track-based route along which the asset is to be transported to the destination is then automatically determined. In order to automatically determine the track-based route, the integrity of the track and/or the track bed may be determined. When determined necessary in order to transport the asset to the destination, the track may be automatically reconfigured, such as by closing or opening appropriate switches. Further, the movement of the asset may be controlled in an autonomous manner along the track while continuing to monitor at least that portion of the track between the asset and the destination.

It is relatively commonplace to need to ship an asset from one location to another, that is, to a destination. While such shipment may be relatively straightforward in many instances, such as when ample time exists for the shipment and when the asset is lightweight and/or relatively small or the like. However, in some instances, the shipment of an asset to a destination can be relatively complex, such as in instances in which the asset is quite large and/or extremely heavy, is combustible, explosive or otherwise presents a danger if mishandled and/or must be transported extremely rapidly.
For example, in a military context, certain weapons, such as a rocket booster having an attached warhead, may need to be shipped from a staging or storage area to a destination for launch. In this scenario, the rocket booster and associated warhead is extremely heavy, oftentimes weighing, for example, about 200,000 pounds. As such, the rocket booster with associated an warhead can only be transported via certain modes of transportation, such as via a railcar. Additionally, the speed with which the rocket booster and associated warhead may be transported over the track may also be limited by the size and weight of the rocket booster and associated warhead since care must be taken to ensure that the rocket booster and associated warhead safely travel over the tracks in a controlled fashion without excessive acceleration, deceleration or other forces which could adversely affect the rocket booster and associated warhead.
As a result of the need to transport the rocket booster and associated warhead in a controlled fashion, the transportation of the rocket booster and associated warhead along the tracks has generally been controlled by a person that may walk or ride along the tracks with the rocket booster and associated warhead. While this approach is generally sufficient in terms of moving the rocket booster and associated warhead from the storage or staging area to its intended destination from which it may be launched, the inclusion of a person in the transportation process for controlling the movement of the rocket booster and the associated warhead limits the speed with which the rocket booster and associated warhead may be transported from the storage or staging location to its intended destination.
In some instances, it may be desirable to transport assets that are a challenge to transport, such as due to weight, size, explosiveness, etc., more quickly than is permitted by a transportation process that requires a person to be integrally involved. As such, it would be desirable to provide an improved technique for transporting assets, such as assets that pose particular challenges to their shipment, such as assets that are heavy, large, explosive or the like, that can safely and reliably transport the asset to an intended destination in a relatively quick fashion.

Autonomous asset transportation method, apparatus and computer program product


There is provided an apparatus for equalization of a battery pack that is composed of plural battery cells. The apparatus includes: a cell balancing device equalizing the voltages of the plural battery cells; a battery cell monitor monitoring the voltage and/or current of each battery cell; a correction voltage calculator calculating correction voltage for a subject battery cell that needs to be equalized, based on the monitored voltage and/or current of the subject battery cell, wherein the correction voltage depends on internal resistance of the subject battery cell; and a cell balancing controller determining the subject battery cell. The cell balancing controller corrects target voltage for equalization of the subject battery cell by the calculated correction voltage, and causes the cell balancing device to execute equalization of the subject battery cell so that the monitored voltage of the subject battery cell reaches the corrected target voltage.

Vehicles having an electric motor in addition to an engine as a power source, such as hybrid car, plug-in hybrid car, hybrid vehicle and hybrid electric vehicle, and transport machinery (hereinafter referred to as vehicle) have been put into practical use. In addition, electric vehicles having no engine and driven only by an electric motor have also been put into practical use. A battery, such as a lithium-ion battery which is compact and has a large capacity, has been used as a power source for driving the electric motor for such vehicle. For vehicle application, the battery may be of a battery pack which is composed of plural cell blocks each having plural battery cells connected in series. The series connection of the battery cells allows supply of the voltage that is required to drive an electric motor of a vehicle and the series or parallel connection of the cell blocks allows supply of electrical current of the required capacity and also provides a higher voltage.
The property of a lithium-ion battery is varied greatly depending on the temperature, and the remaining capacity and charging efficiency of the battery are influenced greatly by the temperature in the environment where the battery is used. This is all the more true of the environment where the vehicle is used.
As a result, there occurs a great variation in the remaining capacity and the output voltage of the respective battery cells in the cell block. In this case, when the voltage of any one of the battery cells is decreased below a threshold, power supply for the whole of the battery needs to be stopped or suppressed, with the result that the power efficiency is lowered. Thus, battery equalization control for equalizing the voltages of the battery cells needs to be performed, and equalization of the voltages of the cell blocks also needs to be performed.
One of the known battery equalization method is a passive equalization that causes an overcharged or overdischarged battery cell to discharge through a bypass resistor connected in parallel to the battery cell so as to equalize the voltages of the battery cells. Another known battery equalization is an active equalization that takes charge from a battery cell of a higher voltage and delivers the charge to a battery cell of a lower battery cell through a converter circuit using an inductor or transformer. In either battery equalization, discharging or charging is done until the voltage of such battery cell reaches target voltage. In the active equalization, the target voltage corresponds to the average of the highest and lowest voltages of the plural battery cells. The battery cell with the highest voltage is discharged to the target voltage, while the battery cell with the lowest voltage is charged to the target voltage. In the passive equalization, the target voltage corresponds to the lowest voltage of the plural battery cells. The battery cells with higher voltages are discharged to the target voltage.
The battery cells have different internal resistances depending on the variation of the characteristics and the degree of deterioration of the respective battery cells. When the equalization is done so that the voltage of the battery cell reaches the target voltage, the voltage of the battery cell monitored during discharging or charging varies from the actual output voltage of the battery cell due to the internal resistance of the battery cell. Thus, when the equalization is done so that the monitored voltage of the battery cell reaches the target voltage, the final voltage of the battery cell is not the same due to the internal resistance of the battery cell. Correction of such variation requires repeated equalization and is time consuming, resulting in increased battery energy loss. In the active equalization, current for equalization is small when the monitored voltage is close to the target voltage, resulting in decreased efficiency and increased loss of the equalization circuit.
The present invention is directed to providing an apparatus and a method which allows quick and efficient equalization of the voltages of the plural battery cells having different internal resistances thereby to offer optimum equalization control.

Apparatus and method for battery equalization


A dielectric ceramic composition including: a barium titanate containing principal component represented by the formula: (1-.alpha.-.beta.-.gamma.){BaO}.sub.m .multidot.TiO.sub.2 +.alpha.M.sub.2 O.sub.3 +.beta.Re.sub.2 O.sub.3 +.gamma.(Mn.sub.1-x-y Ni.sub.x Co.sub.y)O wherein M.sub.2 O.sub.3 is at least one of Sc.sub.2 O.sub.3 and Y.sub.2 O.sub.3 ; Re.sub.2 O.sub.3 is at least one of Sm.sub.2 O.sub.3, Eu.sub.2 O.sub.3, and Gd.sub.2 O.sub.3 ; 0.0025.ltoreq..alpha.+.beta..ltoreq.0.025, 0<.beta..ltoreq.0.0075, 0.0025.ltoreq..gamma..ltoreq.0.05, .gamma./(.alpha.+.beta.).ltoreq.4, 0.ltoreq.x<1.0, 0.ltoreq.y<1.0, 0.ltoreq.x+y<1.0, and 1.000<m.ltoreq.1.035, at least one of scandium oxide and yttrium oxide, at least one of samarium oxide, europium oxide and gadolinium oxide, and at least one oxide of magnesium in an amount of from about 0.5 to 5.0 mols calculated as MgO to 100 mols of the principal components and further containing from about 0.2 to 3.0 parts by weight of an Al.sub.2 O.sub.3 --MO--B.sub.2 O.sub.3 oxide glass, wherein MO is at least one of BaO, CaO, SrO, MgO, ZnO, and MnO, to 100 parts by weight of the sum total of the principal components and magnesium oxide.

The production process for a monolithic ceramic capacitor is generally as follows. First, sheet-form dielectric ceramic materials having a surface which is coated with an electrode material which becomes an internal electrode, are prepared. As the dielectric ceramic material, for example, a material made of BaTiO.sub.3 as the principal component is used. Then, the sheet-form dielectric ceramic materials coated with the electrode material are laminated by pressing under heat and by calcining the integrated laminate at a temperature of from 1,250 to 1,350.degree. C., a dielectric ceramic having internal electrodes is obtained. Also, by firing external electrodes to connect to the internal electrodes at the edge surfaces, a monolithic ceramic capacitor is obtained.
Accordingly, the material of the internal electrode is required to meet to following conditions:
(a) Because the dielectric ceramic and the internal electrodes are simultaneously calcined, the material of the internal electrode has a melting point which is the same as or higher than the temperature at which the dielectric ceramic is calcined.
(b) The material is not oxidized even in an oxidative high-temperature atmosphere and does not react with the dielectric ceramic.
As the electrodes meeting such conditions, a noble metal or alloy thereof, such as platinum, gold, palladium, silver-palladium alloy and the like, has been used. However, although these electrode materials have excellent characteristics, they are expensive, and are the largest factor increasing the production cost of monolithic ceramic capacitors.
Other high-melting materials include such base metals as Ni, Fe, Co, W, Mo and the like but these base metals are easily oxidized in a high-temperate oxidative atmosphere, whereby they become unusable as an electrode. Accordingly, to use these base metals as the internal electrodes of a monolithic ceramic capacitor, it is necessary to calcine the base metal together with a dielectric ceramic in a neutral or reducing atmosphere. However, conventional dielectric ceramic materials have the fault that when the materials are calcined in such a neutral or reducing atmosphere, they are greatly reduced and become semiconductor-like materials.
To overcome the fault described above, there are proposed, for example, a dielectric ceramic material wherein the barium site/titanium site ratio is in excess of the stoichiometric ratio in a barium titanate solid solution as shown in JP-B-57-42588 and a dielectric ceramic material made up of a barium titanate solid solution added with an oxide of a rare earth element such as La, Nd, Sm, Dy, Y, etc., as shown in JP-A-61-101459.
Also, as a dielectric ceramic material having a reduced temperature change of the dielectric constant, there are proposed, for example, a dielectric ceramic material of a BaTiO.sub.3 --CaZrO.sub.3 --MnO--MgO series composition as shown in JP-A-62-256422 and a dielectric ceramic material of a BaTiO.sub.3 --(Mg, Zn, Sr, Ca)O--B.sub.2 O.sub.3 --SiO.sub.2 series composition as shown in JP-B-61-14611.
By using such dielectric ceramic materials as described above, a dielectric ceramic which does not become a semiconductor-like material even when the material is calcined in a reducing atmosphere and the production of a monolithic ceramic capacitor using a base metal such as nickel and the like as the internal electrodes becomes possible.
With recent developments in electronics, the small-sizing of electronic parts has proceeded quickly and the desire to increase the capacity of monolithic ceramic capacitors has also become remarkable. Thus, the increase of the dielectric constant of a dielectric ceramic material and thinning of a dielectric ceramic layer have proceeded very quickly. Accordingly, the demand for a dielectric ceramic material having a high dielectric constant, showing a small temperature change of the dielectric constant, and having excellent reliability has become large.
The dielectric ceramic materials shown in JP-B-57-42588 and JP-A-61-101459 give a large dielectric constant but have the faults that the crystal grains of the dielectric ceramic obtained are large so that when the thickness of the dielectric ceramic layer in the monolithic ceramic capacitor becomes thin as 10 .mu.m or thinner, the number of the crystal grains in each layer is reduced, and the reliability is lowered. Furthermore, there is also a problem in the dielectric ceramic materials that the temperature change of the dielectric constant is large. Thus, the above-described dielectric ceramic materials cannot meet the requirements of the market.
Also, the dielectric constant in the dielectric ceramic material shown in JP-A-62-256422 is relatively high, the crystal grains of the dielectric ceramic obtained are small and the temperature change of the dielectric constant is small but because CaZrO.sub.3 and also CaTiO.sub.3 formed in the calcining process are liable to form a secondary phase with MnO, etc., there is a problem of reliability at high temperature.
Furthermore, there are faults in the dielectric ceramic material shown in JP-B-61-14611 in that the dielectric constant of the dielectric ceramic obtained is from 2,000 to 2,800 and that the material is disadvantageous from the view point of small-sizing and increasing the capacity of the monolithic ceramic capacitor. Also, there is a problem in that the dielectric ceramic material cannot satisfy the X7R characteristics prescribed by the EIA standard, that is, the characteristic that the changing ratio of the electrostatic capacity is within 15% in the temperature range of from -55.degree. C. to +125.degree. C.
Moreover, in the non-reducing dielectric ceramic disclosed in JP-A-63-103861, the insulation resistance and the temperature changing ratio of the capacity are largely influenced by the crystal size of BaTiO.sub.3, which is the principal component, whereby control for obtaining stable characteristics is difficult. Also, when the insulation resistance is shown as the product with the electrostatic capacity (i.e., CR), that product is from 1,000 to 2,000 M.OMEGA..multidot..mu.F and thus, it cannot be said that the non-reducing dielectric ceramic is commercially usable.
To solve the above-described problems, various components are proposed in JP-A-5-9066, JP-A-5-9067, and JP-A-5-9068. However, as a result of the requirement for further small-sizing and further increasing capacity, the requirements of the market for thinning the thickness of the dielectric ceramic layer and more severe reliability requirements, the need for a dielectric ceramic material having even better reliability and ability to cope with thinning the layer thickness have increased.
When a dielectric ceramic layer is simply thinned at a definite rated voltage, the field strength per layer is increased. Accordingly, the insulation resistance at room temperature and high temperature is lowered and the reliability is greatly lowered. Thus, it is necessary to lower the rated voltage when thinning the dielectric ceramic layer in conventional dielectric ceramic.
Accordingly, the necessary of providing a monolithic ceramic capacitor which does not require lowering the rated voltage even when the thickness of the dielectric ceramic layer is thinned, has a high insulation resistance under a high electric field strength, and has excellent reliability, has occurred.
To cope with surface mounting in a small-sized and large capacity monolithic ceramic capacitor, a plated film of a soft solder, etc., is formed on the external electrode formed by baking an electrically conductive metal powder. An electrolytic plating method is generally used as the method of forming the plated film. In the case of forming the plated film on the fired electrode, there is a problem in that when the monolithic ceramic capacitor is immersed in the plating liquid, the liquid enters through the voids of the baked electrode and reaches the interface between the internal electrode and the dielectric ceramic layer to lower the reliability.


A method of initializing a brake-by-wire system is provided. The method includes connecting multiple braking actuators to a controller to allow for communication between the braking actuators and the controller. The braking actuators are associated with one or more wheels of a vehicle. Subsequent to connecting the multiple braking actuators to a controller, the method includes dynamically assigning a primary identifier to the braking actuators using the controller.

Automotive vehicles have been produced or demonstrated with brake systems that modulate brake force during stops to provide anti-lock brake control (ABS) and/or that modulate brake force during vehicle acceleration to provide positive acceleration traction control (TCS). Some such brake systems additionally provide brake-by-wire control.
Typically, brake systems having brake-by-wire control include braking actuators that are pre-programmed with a specific network identification or set of identifications prior to their assembly to the vehicle. For human identification, the actuators and related components are specially keyed, color-coded and/or separated by a large distance to minimize potential for cross-wiring during installation and assembly of the vehicle.

Dynamic identification of brake-by-wire components


Disclosed are methods and network nodes for allocating resources for multiple radio links in a wireless communication system. The method may include successively performing each of multiple scheduling loops such that the resources with one or more of multiple resource types are allocated to one or more radio links selected from the multiple radio links, wherein each of the multiple scheduling loops is associated with the one or more of multiple types of the resources. With the proposed methods and network nodes, radio resources of different types may be effectively and efficiently allocated to multiple radio links through multiple scheduling loops and utilization efficiency of the resources could be notably boosted.

This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Mobile communication technologies are now evolving to very high frequencies, larger carrier bandwidths, very high data rates and multiple heterogeneous layers. The future mobile networks are likely to be a combination of evolved 3G technologies, 4G technologies and emerging or substantially new components such as Ultra-Density Network ("UDN"), which is also referred to as mmW-radio access technology ("RAT"). Due to the increasing demand for wireless capacity enhancement and the lack of availability of spectrum in the lower frequency range (e.g., 800 MHz˜3 GHz), the use of frequencies in 10 GHz range is being investigated and higher frequency bands, for instance, in the range of 30 GHz, 60 GHz and 98 GHz for future mobile networks are also explored. At these high frequency bands, a very large bandwidth of spectrum could be obtained. This means that both operating frequency and bandwidth for the future mobile networks are expected to be much higher than those used in the legacy mobile networks. However, due to large signal attenuation with respect to path loss, the network operating over such high frequencies is supposed to cover small areas with densely deployed radio access nodes ("ANs") or access points ("APs"), such as base stations, thereby providing sufficient coverage for indoor/hot areas.
It has been proposed that the total carrier bandwidth of the mmW-RAT may be up to 1 or 2 GHz. This bandwidth may be composed of a number of sub-band carriers of a certain bandwidth, for example, 100 MHz. By way of example, FIG. 1a schematically illustrates one mmW-RAT carrier with 4 sub-bands in a frequency domain (vertical axis) and with 12 sub-frames in a time domain (horizontal axis). The smallest resource grid in the time-frequency domain is an Atomic Scheduling Unit ("ASU") as illustrated in FIG. 1a.
Scheduling based resource allocation, i.e., scheduled Media Access Control ("MAC"), has been proposed as one possible radio resource allocation approach for the mmW-RAT. For an easy understanding of this scheduled MAC approach, FIG. 1b schematically illustrates a wireless communication system 10 in which the scheduled MAC may be implemented.
As illustrated in FIG. 1b, the wireless communication system 10 includes, among other things, a Central Control Unit ("CCU") 11, a number of Access Nodes ("ANs") 12-15, and a number of user equipments ("UEs") 16-21, wherein the CCU may communicatively connect with multiple ANs and each AN may wirelessly serve multiple UEs within its coverage area. The CCU 11 is responsible for determining a frame, which may also be referred to as a template frame, for each radio link based on measurements and data rate requests from peer nodes of each radio link, for example, an uplink ("UL") and a downlink ("DL") of the UE 16 and an uplink and a downlink of the UE 17. The frame may be configured to indicate, for each radio link, multiple types of resources with different degrees of availabilities, which are illustrated in detail in FIG. 3.
As illustrated in FIG. 3, two different template frames are formed, the top one being directed to UE 1, which may be equivalent to UE 16 in FIG. 1b, and the below one being directed to UE 2, which may be equivalent to UE 17 in FIG. 1b. As can be seen from each template frame, three different types of the resources with respective different availabilities are depicted with respective filled patterns for DL and UL transmission of the UEs.
Specifically, dedicated-type resources are exclusively used by a specific radio link to provide reliable UL/DL data transmission with no significant interference. Opportunistic/shared-type resources are shared between different coexisting radio links and supposed to boost the user data rate when necessary, possibly with interference coming from nearby ongoing communications. Unused-type resources are those resources that are prohibitive for utilization by a certain link, for example via the CCU's initial decision, and may be temporally available for the certain link after the AP's resource coordination among multiple radio links. For example, for a pair of radio links, that is, a first radio link (e.g., DL of the UE 1) and a second radio link (e.g., DL of the UE 2), the unused-type resources, which cannot be used by the second radio link and therefore should be considered as prohibitive for the second radio link, may be dedicated-type resources to be used by the first radio link, as depicted in FIG. 3. Upon the resource coordination, for example, by collecting resource information from other UEs and ANs, the AN may know that the first radio link does not fully use its dedicated-type resources, which are unused-type resources for the second radio link, and therefore may schedule data originated from the second radio link to transmit over its unused-type resources.
Per the CCU shared by a cluster of access nodes, the resources are allocated to different radio links with template frames. The template frame may be updated by the CCU during the session according to various variations such as interference measurements and data rate requests from interactive neighboring radio links.
It is to be understood from the depiction of FIG. 3 that there are multiple radio resource types in the mmW-RAT system for a radio link with template-frame based scheduled MAC and every radio link may be scheduled with one or more types of radio resources. Although the template frame may be configured separately for each radio link and thereby it is straightforward that a radio link should use its own dedicated resources first, it is still insufficient in determining which radio link should be scheduled. That is, the resource availabilities conveyed by the template frame alone cannot determine which radio link should be scheduled and which resource should be allocated for a scheduled radio link when multiple candidate radio links are available to be scheduled.
For example, in an example scenario in which the AN may only have 2 radio frequency ("RF") chains and the DL radio link and UL radio link are served by the different RF chains, in case of high gain analog beamforming is applied in AN side, the AN can only generate up to 2 beam lobes in two different directions and thereby can only serve up to 2 UL or DL radio links in the different directions. Hence, the AN would have to select up to 2 radio links with the same UL or DL direction even though there are 4 candidate radio links with their respective dedicated resources as conveyed by the template frame. Further, the configuration of the template frame cannot indicate which radio link should use which part of resources once for all, especially for the opportunistic/shared-type and unused-type resources whose utilization are flexible and changing, and for the dedicated-type resources which may become useable by other neighboring radio links after scheduling.
In addition, the scheduling priority and resource allocation for the radio link using opportunistic/shared-type resources and/or unused-type resources may be different from those for the dedicated-type resources, since opportunistic/shared-type and/or unused-type resources are shared among neighboring radio links while the dedicated-type resources are dedicated for a certain radio link. Additionally, different types of resources for one link may correspond to different data transmission reliabilities due to interference differences. For instance, a first radio link having better radio quality than a second radio link over the respective dedicated-type resources does not necessarily mean that the first radio link also has better radio quality than the second radio link over the opportunistic/shared-type resources.
In view of the above, how to efficiently schedule and allocate radio resources for candidate radio links in a wireless communication system using, for example, mmW-RAT should be addressed.

Methods and network nodes for allocating resources for multiple radio links


A current mode DC-DC conversion device with fast transient response is provided. The device includes a DC-DC converter, a pulse width control unit, a current feedback circuit, a fast transient feedback circuit, a first error amplifier, an adder, and a comparator. The current feedback circuit generates a current feedback signal according to the current passing through an inductor in the DC-DC converter. The fast transient feedback circuit generates a transient feedback signal according to a first voltage feedback signal. The first error amplifier amplifies the difference value between a second voltage feedback signal and a reference signal to generate an error amplification signal. The comparator compares the error amplification signal and the summation of current feedback signal and transient feedback signal to generate a comparison signal. The comparison signal is provided to the pulse width control unit for controlling the duty cycle of the power switch.

1. Field of the Invention
The present disclosure relates to a current mode DC-DC conversion device; in particular, to a current mode DC-DC conversion device with fast transient response.
2. Description of Related Art
The DC-DC converter is for converting the DC input voltage into the DC output voltage. For the controlling of the DC-DC converter, the control method of both the boost converter and the buck converter can be distinguished into two modes including the voltage mode and the current mode. The principles of the voltage mode controlling mainly depend on detecting the changes of the output voltage and controlling the output voltage to an expected value according to the circuit feedback mechanics. The principles of the current mode controlling mainly depend on detecting the current changes of the inductors for accelerating the transient response time caused by the changes of the loads. Comparing with the voltage mode controlling, the current mode controlling has better load regulation and line regulation capabilities, and has faster transient response.

Current mode DC-DC conversion device with fast transient response


A device such as for example a electronic medical device has a memory that has prestored therein a number of programs or routines for performing various functions. Some of those functions are optional functions that were not enabled when the equipment was put into service. If the user of the equipment desires thereafter to activate any one of those optional functions, an options card that has a number of memory blocks each specifically configured to enable one of the prestored optional functions is sent to the user. The user can then insert the options card into a receptacle integrated into the device and, upon power up of the device, elect a menu for enabling the desired optional function(s) prestored in the device. The options card may be configured to have a count number that indicates the number of devices the card may be used for enabling a particular optional function. The options card may further be configured to include data that may be used to enable or disable multiple optional functions prestored in the device. When returned to the manufacturer, given that the serial numbers of the machines to which the options card was inserted are recorded therein, the manufacturer can easily keep tab of the status of those machines in the field that had had optional functions enabled/disabled.

When an electronic device is put into service, oftentimes the internal programs for running the device or functions performed by such device require alteration or updating. This is done in the prior art by inputting into such device a new program or new update codes. Whitley et al. U.S. Pat. No. 5,590,373 discloses one such method of updating the programs in an electronic device, in this instance a field programmable personal communications device (PDI). To achieve the updating of the programs within the PDI, Whitley teaches that a PCMCIA (Personal Computer Memory Card International Association) card could be used. In particular, a new program is stored in the PCMCIA card and, upon insertion of this card into the appropriate receptacle of the PDI device, the new program is transferred into the electrically programmable read only memory (EPROM) of the PDI so that the functions performed by the PDI may be reconfigured. In otherwords, the program within the PDI is replaced by the new program fed thereinto by the PCMCIA card. It means that the PCMCIA card has to have sufficient memory, particularly when a large program is to be stored therein, for reconfiguring the PDI. Furthermore, problems may be encountered when updating the internal program of the PDI with the new program from the PCMCIA card, insofar as oftentimes some type of interaction has to take place between the user and the device, as the new program is being loaded into the PDI device.
The prior art further teaches that a memory card such as a PCMCIA card may be used for transferring information between a standalone device, such as for example a vending machine or a parking meter, so that data may be transferred between the memory card and the device. One such example is disclosed in Cagliostro U.S. Pat. No. 5,500,517 which discloses the use of a PCMCIA card for transferring information to a device for updating the cost for using the device and the prices of goods to be sold from the device.
In terms of medical devices, Armstrong et al. U.S. Pat. No. 5,606,978 discloses a heart monitoring device that has a slot for accepting an IC card, which contains specific control data that is used to control the programs stored in the device, to thereby control the operation of the device. Moberg U.S. Pat. No. 5,265,607 also discloses a medical device, in this instance an EEG monitor that includes a head box that has a housing adapted to be fitted with a configuration card. Such configuration card is electrically and mechanically compatible with the housing and is configured to provide a particular type of monitoring procedure so that a specific type of EEG waveform from the patient may be monitored.
In a medical environment, it is desirable that a care provider not be distracted by having to deal with the reprogramming of a device, as is required in the prior art discussed above. Moreover, any function to be performed by a device in a medical setting has to be reliable, i.e., it has to be fully tested when the device is put into service. Any tuning or tampering of the program in order to make it run properly in such medical device is unacceptable in a patient environment. Accordingly, a fool proof method of providing a new function to a device, especially a medical device, is required.

Memory option card having predetermined number of activation/deactivation codes for selectively activating and deactivating option functions for a medical device


A low differential check valve is provided for a fire control system, having particular adaptability in a dry system. The check valve is maintained in its closed position by a latch which is controlled by a plunger. The plunger is activated, and moved to release the latch, upon the sensing of drop in system air pressure by a higher differential mechanism external of the check valve. The check valve may then be reset, with its clapper moved to its closed condition, without requiring internal access of the check valve to release a clapper latch.

Fire control sprinkler systems generally include a plurality of individual sprinkler heads which are usually ceiling mounted about the area to be protected. The sprinkler heads are normally maintained in a closed condition and include a thermally responsive sensing member to determine when a fire condition has occurred. Upon actuation of the thermally responsive member the sprinkler head is opened, permitting pressurized water at each of the individual sprinkler heads to freely flow therethrough for extinguishing the fire. The individual sprinkler heads are spaced apart from each other, by distances determined by the type of protection they are intended to provide (e.g. light or ordinary hazard conditions) and the ratings of the individual sprinklers, as determined by industry accepted rating agencies such as Underwriters Laboratories, Inc., Factory Mutual Research Corp. and/or the National Fire Protection Association. It should be well appreciated that once the sprinkler heads have been thermally activated there should be minimal delay for the water flow through the sprinkler head at its maximum intended volume.
In order to minimize the delay between thermal actuation and proper dispensing of water by the sprinkler head, the piping that connects the sprinkler heads to the water source is, in many instances at all times filled with water. This is known as a wet system, with the water being immediately available at the sprinkler head upon its thermal actuation. However, there are many situations in which the sprinkler system is installed in an unheated area, such as warehouses. In those situations, if a wet system is used, and in particular since the water is not flowing within the piping system over long periods of time, there is a danger of the water within the pipes freezing. This will not only deleteriously affect the operation of the sprinkler system, should the sprinkler heads be thermally actuated while there may be ice blockage within the pipes, but such freezing, if extensive, can result in the bursting of the pipes, thereby destroying the sprinkler system. Accordingly, in those situations it is the conventional practice to have the piping devoid of any water during its non-activated condition. This is known as a dry fire protection system.
While all fire protection sprinkler systems generally include a check valve for isolating the sprinkler system piping from the pressurized water source during the non-activated condition, the design of such check valves for a dry type fire control sprinkler system has presented various problems. The check valve, which is interposed between the system piping and pressurized water source, includes a clapper, which when it is in its closed operative condition prevents the flow of the pressurized water into the sprinkler system piping. The sprinkler piping in the dry fire protection system will include air or some other inert gas (e.g. nitrogen) under pressure. The pressurized air, which is present within the sprinkler system piping, is also presented to the check valve. Should one or more of the sprinkler heads be thermally activated to its open condition, the pressure of the air within the sprinkler system piping and check valve will then drop. The check valve must be appropriately responsive to this drop pressure, normally in opposition to the system water pressure also present in the check valve, to move the clapper to its open condition. When this occurs, it is desirable to have a rapid expulsion of the pressurized air within the check valve and the sprinkler system piping, to permit the rapid flow of the pressurized water through the open check valve, into the sprinkler system piping, and through the individual sprinkler heads to rapidly extinguish the fire.
The check valves intended for dry type fire control sprinkler systems have typically controlled the clapper movement by the water and the air pressure applied to its opposite sides. Such fire check valves include an air seal which opposes the pressurized water seal. To appropriately apply the system air pressure over the surface of the clapper air seal, a priming water level is oftentimes maintained within the check valve. During normal conditions, when no sprinkler heads have been activated, the two seals will be an equilibrium, thereby maintaining the clapper in its closed condition.
In order to increase the speed of check valve operation upon a drop off of the system air pressure, occasioned by the activation of one or more sprinkler heads, the system air pressure is normally applied to the clapper air seal over a substantially greater area then the water pressure is applied to the clapper water seal. This is known as a high differential type check valve. A problem of such valves is that should there then be a reduction in the system water pressure after the clapper has opened, and particularly since the pressure against the opposite (air) side of the clapper has been increased with the column of water that has flowed therethrough, there is a tendency of the clapper to reclose. Since the pressure applied against the air seal of the clapper will now be increased by the column of water extending upwards from the reclosed check valve, a greater water pressure would now be required to move the clapper to its open condition. Such disadvantageous reclosure, is referred to as a water columning effect. This could result in failure of the check valve to subsequently open should one or more of the sprinkler heads be thermally activated.
In order to avoid the reclosure of the clapper such prior art dry system check valves have generally been provided with a mechanical latch to maintain the clapper in its open condition once it has been activated. The inclusion of such a mechanical latch, while serving to prevent reclosure, disadvantageously requires the entire sprinkler system to be shut down and the interior of the high differential type actuator accessed to release the latch and reclose the clapper after the fire has been extinguished. Thus prior dry system check valves have typically required the main supply of water to be shut off, the water drained from the system, and then the high differential check valve opened to manually unlatch and reset the clapper. Recognizing the disadvantage of having to manually access the interior of the check valve a mechanism is shown in U.S. Pat. Nos. 5,295,503 and 5,439,028 which includes a reset linkage mechanism attached to the check valve, and actuated by the rotation of an externally accessible handle. As can be well appreciated such a mechanism adds to the size, cost and complexity of the check valve.

Low differential check valve for sprinkler systems