A metal-containing monomer dissolved mixture comprising a reaction product of an inorganic metal compound with a carboxyl group-containing radical polymerizable monomer, an organic solvent including at least an alcohol-based solvent, and water, wherein the water content is from 0.01 to 30% by weight; a metal-containing resin obtained by copolymerizing the metal-containing monomer (A) in this dissolved mixture with the other radical-polymerizable unsaturated monomer (B); an antifouling paint composition obtained by using this metal-containing resin; and an antifouling paint composition comprising a divalent metal-containing resin (C), a compound (D) of R1xe2x80x94SH (wherein, R1 represents an organic group having 1 to 30 carbon atoms.), and copper oxide (E), are disclosed.

1. Field of the Invention
The present invention relates to a metal-containing monomer dissolved mixture, a metal-containing resin and an antifouling paint composition. More particularly, the present invention relates to a metal-containing monomer dissolved mixture which is soluble in a general organic solvent, excellent in storage stability and can be mixed with a general acrylic monomer and the like; a metal-containing resin soluble in a general organic solvent obtained by using the metal-containing monomer dissolved mixture as a raw material; and antifouling paint composition manifesting antifouling effect in sea for a long period of time.
2. Description of the Prior Art
Metal-containing monomers have been conventionally investigated to be used as an additive into an aqueous paint, aqueous ink, ultraviolet ray-curing material and the like, and usually, handled in the form of a powder or aqueous solution. In the case of a powder, it can be used as a modifier and the like for generally used resins such as an acrylic resin, epoxy resin, urethane resin, polyester resin and the like, and in the case of an aqueous solution, it can be used as a cross-linking agent and the like for a water-soluble resin and emulsion resin.
Metal-containing resins can be applied to various uses, and among them, use as a resin for an antifouling paint utilizing hydrolysis property thereof is expected.
An antifouling paint is painted, for example, on parts of ships and marine structures immersed in water for the purpose of preventing corrosion due to adhesion of marine organisms such as barnacle, teredo, algae and the like and reduction in navigating speed of a ship. Further, the same antifouling paint is painted also on a fish farming net for the purpose of preventing death of fishes due to adhesion of marine organisms.
A painted film formed of such an antifouling paint manifests an antifouling effect, for example, by elution of a rosin-based compound and antifouling component contained in the film into sea. However, when this painted film is immersed in sea for a long period of time, the proportion of an elution component decreases gradually to increase the proportion of non-eluting components, simultaneously the surface of the painted film becomes uneven, consequently, there is a tendency of significant reduction in an effect of preventing adhesion of organisms such as marine organisms and the like.
An organotin-based paint is conventionally used as an antifouling paint. This organotin-based antifouling paint is characteristic in that a painted film formed is gradually solved from the surface of the film to renew the surface, and an antifouling component is constantly exposed on the surface of the film (self polishing), consequently, an antifouling effect is manifested for a long period of time.
However, there is an afraid that an organotin-based antifouling paint exerts a reverse influence on fishes due to strong toxicity of organotin. Therefore, paints containing no organotin are on investigation. For example, an antifouling paint using an organosilicon-containing resin in which an organosilicon ester is introduced in a side chain, and antifouling paints using resins containing other metals than tin, have been suggested. Among others, antifouling paints using resins containing other metals than tin are noticed from the standpoints of an antifouling effect, cost and the like. For example, JP-A No. 63-56510 describes that a disintegrating type vinyl resin particle obtained by polymerizing a metal ester type polyfunctional polymerizable monomer can be added in an antifouling paint.
However, a painted film containing such a disintegrating type vinyl resin particle has problem that when immersed in sea for a long period, the surface of the film becomes uneven, and an antifouling ability thereof decreases significantly. For solving this problem, it is necessary that the metal-containing resin functions as a vehicle component of an antifouling paint, however, since a particle of such a metal-containing resin is scarcely soluble in a general solvent, use as a vehicle component is difficult. Namely, a metal-containing resin soluble in general solvent has been desired as a resin for an antifouling paint.
For example, JP-B No. 61-3830 suggests a metal-containing resin obtained by ion-changing a high acid value polymer or copolymer having a carboxyl group with a metal salt solution, and causing precipitation of a resin with an aqueous medium. Further, JP-A No. 5-171066 suggests an antifouling paint composition using as a vehicle component a copolymer constituted of a monomer having two or three double bonds and containing a metal. Further, JP-A Nos. 62-57464 and 62-84168 suggest self polishing type antifouling paint compositions using a copolymer having a specific divalent metal-containing group at the end of a side chain.
Most of metal-containing monomers typified by metal salts of polymerizable unsaturated organic acids are solid powders under normal temperature and normal pressure, and easily dissolved in water, however, are not easily dissolved in general organic solvents. Such metal-containing monomers are dissolved in slight amount in a large amount of alcohol-based solvent, however, when left for a certain period, manifest a tendency of deposition of a crystal, leading to poor storage stability.
When a metal-containing resin is produced by copolymerizing a metal-containing monomer with an acrylic monomer and the like in an organic solvent, copolymerizing property is low because a metal-containing monomer is not easily dissolved also with an acrylic monomer, and it is difficult to introduce a metal in sufficient amount into a polymer. Further, when a metal-containing monomer is added as a cross-linking agent to an acrylic oligomer or the like which is a ultraviolet ray-curing material, to produce a metal-containing resin, degree of cross-linking is low because the monomer is not easily solved uniformly in the oligomer, consequently, it is difficult to obtain sufficient abilities.
When a metal-containing resin obtained by introducing a metal salt into a high acid value resin described in JP-B No. 61-3830 is used as a resin for an antifouling paint, there is a tendency of decrease in water-resistance and antifouling property for a long period of a painted film. Further, this metal-containing resin has a problem that when copper oxide generally used as an antifouling agent causing duration of an excellent antifouling effect in sea for a long period of time is added, the paint is easily gelled.
Moreover, a metal-containing monomer described in JP-A No. 5-171066 has a problem that copolymerizability with acrylic monomers and the like is low, and a copolymer insoluble in a solvent is often obtained, because this metal-containing monomer is not easily dissolved with an organic solvent and acrylic monomer and the like as described above. Further, a film obtained from this antifouling paint composition tends to easily cause cracking and peeling with the lapse of time.
Furthermore, when resins having a specific divalent metal-containing group at the end of a side chain described in JP-A Nos. 62-57464 and 62-84168 are used as a resin for an antifouling resin, stability of hydrolysis of the film is low, and antifouling property of a long period is insufficient. Additionally, there is a problem that, when copper oxide is added, self polishing property decreases, and this tendency becomes remarkable particularly in a paint stored for a long period of time.
An object of the present invention is to provide a metal-containing monomer dissolved mixture which is soluble in a general organic solvent, excellent in storage stability and can be mixed with a general acrylic monomer and the like, a metal-containing resin soluble in a general organic solvent obtained by using this monomer dissolved mixture as a raw material, and an antifouling paint composition manifesting duration of an antifouling effect in sea for a long period of time.
The present inventors have intensively studied for attaining the above-mentioned object, and resultantly found that a metal-containing monomer dissolved mixture comprising, as constituent components, a reaction product of an inorganic metal compound with a carboxyl group-containing radical polymerizable monomer, a specific organic solvent, and water of specific amount; and a metal-containing resin obtained by using this monomer dissolved mixture as a raw material, perform an excellent effect, and that an antifouling paint composition containing this metal-containing resin as a vehicle component, and an antifouling resin composition comprising a divalent metal-containing resin, a specific compound and copper oxide perform an excellent effect, leading to completion of the present invention.
Namely, the present invention provides a metal-containing monomer dissolved mixture comprising a reaction product of an inorganic metal compound with a carboxyl group-containing radical polymerizable monomer, an organic solvent including at least an alcohol-based solvent, and water, wherein the water content is from 0.01 to 30% by weight; further, a metal-containing resin obtained by copolymerizing the metal-containing monomer (A) in this mixture with the other radical-polymerizable unsaturated monomer (B).
Further, the present invention provides an antifouling paint composition obtained by using the above-mentioned metal-containing resin, and an antifouling paint composition comprising a divalent metal-containing resin (C), a compound (D) of the following general formula (I), and copper oxide (E):
R1xe2x80x94SHxe2x80x83xe2x80x83(I)
wherein, R1 represents an organic group having 1 to 30 carbon atoms.
In the present invention, the inorganic metal compound is used as a constituent component of a metal-containing monomer dissolved mixture which is soluble in an organic solvent, and reacts with a carboxyl group-containing radical polymerizable monomer to form a metal salt. As the inorganic metal compound, for example, oxides, hydroxides, chlorides and the like of metals are listed. The inorganic metal compound is not limited to them, and those reacting with a carboxyl group to form a metal salt can be used.
As the oxide of a metal, for example, zinc oxide, aluminum oxide, calcium oxide, copper oxide, magnesium oxide, manganese oxide and the like are listed. As the hydroxide of a metal, for example, zinc hydroxide, aluminum hydroxide, calcium hydroxide, copper hydroxide, magnesium hydroxide and the like are listed. As the chloride of a metal, for example, zinc chloride, aluminum chloride, calcium chloride, cupric chloride, magnesium chloride, manganese chloride and the like are listed.
Metals of the inorganic metal compound are selected from the group consisting of Ib, IIa, IIb, IIIa, IIIb, IVa, IVb, Va, Vb, VIb, VIIb, and VIII group metals in the periodic table, and if necessary, two or more of them may be used. Among them, zinc, magnesium, calcium, copper and aluminum are preferable because a mixture containing them tends to be excellent in storage stability. Further, zinc, magnesium, calcium and aluminum were preferable because resins obtained from them are excellent in transparency. Particularly, divalent zinc and magnesium are preferable because increase in viscosity in producing a resin can be suppressed. When copper is used as a metal in the inorganic metal compound, zinc is preferably used together for the purpose of increasing copolymerizability with an acrylic monomer. From the standpoint of use in an antifouling paint, when zinc or magnesium is used as a metal in the inorganic metal compound, hue of a film of an antifouling paint tends to become beautiful because the resulted metal-containing resin has high transparency, further, because solubility thereof in a general organic solvent is high, productivity of a resin becomes good, and viscosity of the resultant resin and paint tends to be easily controlled by a diluting solvent. Particularly, when zinc is more preferably used because water-resistance of a film becomes good.
In the present invention, disclosed as examples of the carboxyl group-containing radical polymerizable monomer are methacrylic acid, acrylic acid, itaconic acid, (anhydrous) maleic acid, monoalkyl itaconate (alkyl is, for example, methyl, ethyl, butyl, 2-ethylhexyl or the like), monoalkylmaleate (alkyl is, for example, methyl, ethyl, butyl, 2-ethylhexyl or the like), and the like. These can be used alone or in combination of two or more selected appropriately. Among them, methacrylic acid and acrylic acid are preferable because storage stability of the mixture for a long period is excellent.
In the present invention, the organic solvents include at least an alcohol-based solvent. As the alcohol-based solvent, ethanol, isopropanol, butanol, propylene glycol monomethyl ether and the like are preferable, particularly from the standpoint of solubility of a metal salt compound (reaction product). It is not preferable to use an organic solvent containing no alcohol-based solvent because the solution easily loses flowability and is solidified in reaction, and it is difficult to obtain a solution in a transparent state.
Further, if necessary, a mixed solvent composed of an alcohol-based solvent and other organic solvents can be used. As other organic solvents, there are listed, for example, aliphatic hydrocarbon-based solvents such as pentane, hexane, heptane and the like; aromatic hydrocarbon-based solvents such as benzene, toluene, xylene and the like; ester-based solvents such as ethyl acetate, butyl acetate, isobutyl acetate and the like; ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like; etc. In the mixed solvent, the proportion of an alcohol-based solvent is preferably 5 wt % or more. When the proportion is 5 wt % or more, solubility of a metal salt compound (reaction product) in a solvent increases and a crystal is not formed, consequently, storage stability is manifested. More preferably, the proportion is 25 wt % or more.
The preferable metal content of the metal-containing monomer dissolved mixture of the present invention is from 0.1 to 60 wt %. By controlling the proportion to 60 wt % or less, it becomes easy to obtain a metal-containing monomer dissolved mixture in a transparent state, and the copolymerizability of the metal-containing monomer with acrylic monomers becomes high. By controlling the proportion to 0.1 wt % or more, the amount of organic solvent in the mixture can be decreased, and handling property is improved, and in polymerizing the metal-containing resin composition, high solidification is possible. More preferably, the proportion is from 3 to 25 wt %.
The ratio of inorganic metal compound-derived components to carboxyl group-containing radical polymerizable monomer-derived components in the metal-containing monomer dissolved mixture of the present invention is not particularly restricted, and the preferable ratio (molar number) of inorganic metal compound-derived components is 0.6 mol or less based on 1 mol of carboxyl group-containing radical polymerizable monomer-derived components. When this is 0.6 mol or less, transparency of a mixture has no particular, however, when over 0.6 mol, an unreacted inorganic metal compound tends to remain in a mixture, leading to poor transparency of a monomer, therefore, varnish (metal containing resin) obtained by polymerizing this tends to be turbid.
Further, when the metal-containing monomer dissolved mixture of the present invention is used in production of a metal-containing resin as a vehicle for an antifouling paint as described later, regarding the ratio of inorganic metal compound-derived components to carboxyl group-containing radical polymerizable monomer-derived components in the metal-containing monomer dissolved mixture, it is particularly preferable that the ratio (molar number) of inorganic metal compound-derived components is about 0.5 mol based on 1 mol of carboxyl group-containing radical polymerizable monomer-derived components. However, when the ratio (molar number) of inorganic metal compound-derived components is fairly large based on carboxyl group-containing radical polymerizable monomer-derived components, there is no particular problem on film abilities. When the ratio is too small, water-resistance of a film decreases, and when copper oxide is compounded, storage stability of a paint lowers.
The amount was water contained in the metal-containing monomer dissolved mixture of the present invention is preferably from 0.01 to 30 wt %. In the present invention, the term xe2x80x9camount of waterxe2x80x9d excludes the amount water produced by reaction of an inorganic metal compound with a carboxyl group-containing radical polymerizable monomer. All of water may be added in the reaction, or water may be added partially during the reaction and added again after completion of the reaction.
When water is not added during the reaction, a solution tends to lose flowability and is solidified in or directly after the reaction of an inorganic metal compound with a carboxyl group-containing radical polymerizable monomer, consequently, it is difficult that the metal-containing monomer is mixed with an acrylic monomer and polymerized. Further, once solidified, a large amount of water and solvent are necessary for redissolution, consequently, workability decreases due to separation from an acrylic monomer or decrease in solid content. On the other hand, by adding water during the reaction, a reaction solution maintaining flowability in which a metal-containing monomer is dissolved in an organic solvent can be obtained, and it becomes easy to mix and copolymerize it with an acrylic monomer.
The amount of water added during the reaction is preferably 0.01 wt % or more, more preferably 0.2 wt % or more, for keeping solution condition without losing flowability of a solution during the reaction. If a metal-containing monomer dissolved mixture in form of a solution is obtained, it becomes easy to mix and copolymerize it with an acrylic monomer. The amount of water in a metal-containing monomer dissolved mixture is preferably 30 wt % or less, more preferably 15 wt % or less from the standpoints of storage stability at lower temperature of a metal-containing monomer dissolved mixture, solubility in a general acrylic monomer and organic solvent, and copolymerizability with various acrylic monomers.
Further, when the content of organic solvents is increased for the purpose of lowering the water content in a metal-containing monomer dissolved mixture, solid content decreases and the amount of organic solvents used in polymerization increases, therefore, increase in organic solvents is not preferable from the standpoint of high solidification of the resin. For reducing the amount of organic solvents in a metal-containing monomer dissolved mixture, it is preferable that the metal-containing monomer dissolved mixture contains water in a proportion of 0.01 to 5-fold based on the mol number of an inorganic metal compound used, and it is preferable that the solid content of the mixture is from 25 to 70 wt %. Particularly, water of 0.05 to 3-fold mol is preferably contained, and the solid content of a mixture is preferably from 45 to 60 wt %.
Further, when the metal-containing monomer dissolved mixture of the present invention is used in production of a metal-containing resin as a vehicle for an antifouling paint as described later, the water content in the metal-containing monomer dissolved mixture is preferably 20 wt % or less. In this case, the water amount contained in a metal-containing resin decreases, and increase in viscosity in processing into a paint can be suppressed and decrease in hydrolysis property of a film can be suppressed. The water content is more preferably 15 wt % or less.
The metal-containing resin of the present invention is obtained by copolymerizing the metal-containing monomer (A) in the dissolved mixture of the present invention described above with the other radical polymerizable unsaturated monomer (B). The metal-containing resin of the present invention is soluble in a general organic solvent by using the metal-containing monomer dissolved mixture as a raw material. When the metal-containing resin of the present invention is used, for example, as a vehicle for an antifouling paint, the film shows high self polishing property for a long period of time and manifests excellent antifouling effect.
In the metal-containing resin of the present invention as a vehicle for an antifouling paint, the amount of a radical polymerizable unsaturated monomer (B) used is preferably from 16 to 97 parts by weight based on 100 parts by weight of the total amount of the component (A) and component (B). By controlling the amount to 16 parts by weight or more, balance between various properties of the resulting antifouling paint tends to be regulated. By controlling the amount to 97 parts by weight or less, there is a tendency that excellent hydrolysis property for a long period is imparted to the formed film, and balance between cracking resistance and hydrolysis property becomes good. The amount is more preferably from 40 to 90 parts by weight, particularly preferably from 60 to 85 parts by weight.
Examples of the radical polymerizable unsaturated monomer (B) include (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-(2-ethylhexaoxy)ethyl (meth)acrylate, 1-methyl-2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 3-methyl-3-methoxybutyl (meth)acrylate, m-methoxyphenyl (meth)acrylate, p-methoxyphenyl (meth)acrylate, o-methoxyphenylethyl (meth)acrylate, m-methoxyphenylethyl (meth)acrylate, p-methoxyphenyethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, glycidyl (meth)acrylate and the like; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like; adducts of 2-hydroxyethyl (meth)acrylate with ethylene oxide, propylene oxide, xcex3-butyrolactone or xcex5-caprolactone and the like; dimers or trimers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and the like; primary and secondary amino group-containing vinyl monomers such as butylaminoethyl (meth)acrylate, (meth)acrylamide and the like; tertiary amino group-containing vinyl monomers such as dimethylaminoethyl (meth)acrylate, diethylaminmoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, dimethylaminobutyl (meth)acrylate, dibutylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide and the like; heterocyclic basic monomers such as vinylpyrrolidone, vinylpiridine, vinylcarbazole and the like; additionally, vinyl-based monomers such as styrene, vinyltoluene, xcex1-methylstyrene, (meth)acrylonitrile, vinyl acetate, vinyl propionate and the like. In the present invention xe2x80x9c(meth)acrylxe2x80x9d means xe2x80x9cacryl and/or methacrylxe2x80x9d.
The content of a metal in the metal-containing resin of the present invention is preferably from 0.5 to 25 wt %. By controlling the amount to 0.5 wt % or more, self polishing property of the formed film tends to be manifested, and by controlling the amount to 25 wt % or less, there is a tendency that an effect to improved balance between cracking resistance and hydrolysis property becomes remarkable, self polishing property for a long period of time is maintained, and an antifouling effect is improved. More preferably, the amount thereof is from 1 to 10 wt %.
The weight-average molecular weight of the metal-containing resin of the present invention is preferably from 1000 to 20000. By controlling the molecular weight to 20000 or less, metal cross-linking between polymers can be reduced by lowering the viscosity of a resin solution, gelling of a resin can be suppressed, and a metal in amount to manifest hydrolysis property can be integrated into a resin successfully. By controlling the molecular weight to 1000 or more, cracking resistance tends to be manifested. More preferably, the molecular weight is from 3000 to 10000.
A method of producing the metal-containing resin of the present invention is not particularly restricted. For example, it can be produced by mixing a metal-containing monomer dissolved mixture with a radical polymerizable unsaturated monomer, and copolymerizing them in the presence of a radical initiator at a temperature from 60 to 180xc2x0 C. for 5 to 14 hours. When the metal content in a copolymer is increased, a chain transfer agent can be used for high solidification and improvement in productivity, particularly, suppressing of production of insoluble substances in polymerization. From the standpoint of compatibility with a monomer containing a metal, chain transfer agents other than mercaptane are preferably, and particularly, a styrene dimer and the like are preferable. As the polymerization method, an emulsion polymerization method, suspension polymerization method and the like can be adopted in addition to a solution polymerization method effected in an organic solvent. Particularly, a solution polymerization method using a general organic solvent such as toluene, xylene, methyl isobutyl ketone, n-butyl acetate or the like is advantageous from the standpoints of productivity and painting ability.
The proportion of a copolymer as a vehicle in an antifouling paint composition is not particularly restricted, and it is preferable to use a copolymer usually in a proportion of 20 to 25 wt % (solid content) as a resin component in an antifouling paint composition. The reason for this is that, by appropriate inclusion of a resin component, film abilities such as cracking resistance and the like tend to become excellent, and by no excess inclusion, inclusion of an antifouling agent in amount sufficient for keeping excellent antifouling ability into an antifouling paint composition tends to become easy.
The antifouling paint composition of the present invention is obtained by using the metal-containing resin of the present invention described above as a vehicle component. The antifouling paint composition of the present invention can keep excellent antifouling ability of a film by using this metal-containing resin. Further, by compounding, for example, an antifouling agent, antifouling ability can also be further improved.
The antifouling agent may be appropriately selected and used depending on requisite abilities. For example, copper-based antifouling agents such as copper oxide, copper thiocyanate, copper powder and the like, metal compounds of lead, zinc, nickel and the like, amine derivatives such as diphenylamine and the like, nitrile compounds, benzothiazole-based compounds, maleimide-based compounds, pyridine-based compounds and the like are listed. These can be used alone or in combination of two or more. Particularly, compounds selected as subjects of investigated by Nippon Senpaku Kogyo Kai are preferable, and specific examples thereof include manganeseethylene bisdithiocarbamate, zincdimethyl dithiocarbamate, 2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine, 2,4,5,6-tetrachloroisophthalonitrile, N,N-dimethyldichlorophenylurea, zinc ethylene bisdithiocarbamate, copper rhodanate, 4,5-dichloro-2-n-ocryl-3(2H) isothiazolone, N-(fluorodichloromethylthio)phthalimide, N,Nxe2x80x2-dimethyl-Nxe2x80x2-phenyl-(N-fluorodichloromethylthio)sulfamide, zinc 2-pyridinethiol-1-oxide, tetramethylthiuram disulfide, Cu-10% Ni solid solution alloy, 2,4,6-trichlorophenylmaleimide, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, 3-iodo-2-propylbutylcarbamate, diiodomethyl p-trisulfone, bisdimethyldithiocarbamoylzincethylene bisdithiocarbamate, phenyl(bispyridyl)bismuth dichloride, 2-(4-thiazolyl)-benzimidazole and pyridine-triphenylborane.
In the antifouling paint composition of the present invention, silicon compounds such as dimethylpolysiloxane, silicone oil and the like, fluorine-containing compounds such as carbon fluoride and the like can also be compounded, additionally, for the purpose of imparting lubricity to the surface of a film and preventing adhesion of organisms. Further, extender pigments, coloring pigments, plasticizers, various paint additives, and other resins and the like can be compounds, if necessary.
The antifouling paint composition of the present invention is applied, for example, by an application means such as brush painting, spraying, roller painting, deposition painting and the like directly on the surface of a substrate of underwater structures such as ships, various fishing nets, bay facilities, oil fences, bridges, submarine bases and the like, or on a film formed by painting a wash primer, chlorinated rubber-based or epoxy-based primers, intermediate coating paint and the like, on a substrate. The application amount is usually an amount to give a thickness of a dry film of 50 to 400 xcexcm. Drying of a painted film is usually conducted at room temperature, and heat drying may be effected without problem.
Another antifouling paint composition of the present invention is an antifouling paint composition comprising a divalent metal-containing resin (C), a compound (D) of the following general formula (I), and copper oxide (E):
R1xe2x80x94SHxe2x80x83xe2x80x83(I)
wherein, R1 represents an organic group having 1 to 30 carbon atoms.
The divalent metal-containing resin is a vehicle component of an antifouling paint composition, and a film formed by this is dissolved gradually in sea to show self polishing. The divalent metals can be selected and used appropriately. From the standpoint of solubility into an organic solvent, zinc, copper, magnesium and calcium are preferable, among them, zinc and copper particularly preferable.
The metal content in the divalent metal-containing resin (C) is preferably from 3 to 25 wt %. By controlling the content to 3 wt % or more, excellent self polishing property tends to be imparted to a film. The content is more preferably 6 wt % or more. By controlling the content to 25 wt % or less, balance between cracking resistance and hydrolysis property of a film is excellent, and self polishing property for along period of time is maintained, and antifouling effect is improved. The content is more preferably 15 wt % or less.
As a method for producing the divalent metal-containing resin (C), for example, a method of adding a metal to a high acid value resin, and a method of copolymerizing a metal-containing polymerizable monomer, are listed. For keeping excellent storage stability of a film and maintaining stable self polishing property of an antifouling film over a long period of time, a method of copolymerizing a metal-containing polymerizable monomer is preferable. This method is specifically a method in which a metal-containing polymerizable monomer (xcex1) and other radical polymerizable unsaturated monomers (xcex2) are copolymerized.
The metal-containing polymerizable monomer (xcex1) is a component used to impart high self polishing property to the resulting film over a long period and to manifest excellent antifouling effect, and particularly, metal-containing polymerizable monomers (xcex11) having two unsaturated groups, and metal-containing polymerizable monomers (xcex12) of the following general formula (II) are preferable.
wherein R2 represents a hydrogen atom or methyl group, M represents Mg, Zn or Cu, R3 represents an organic acid residue.
The amount of the metal-containing polymerizable monomer (xcex11) in the divalent metal-containing resin (C) is not particularly restricted, and preferably from 10 to 80 wt %. By controlling the amount to 10 wt % or more, suitable self polishing property tends to be imparted to a painted film. This amount is more preferably 20 wt % or more. By controlling this amount to 80 wt % or less, antifouling property of a film tends to be maintained. This amount is more preferably 50 wt % or less.
As the metal-containing polymerizable monomer (xcex11) having two unsaturated groups, there are listed, for example, magnesium acrylate [(CH2xe2x95x90CHCOO)2Mg], magnesium methacrylate [(CH2xe2x95x90C(CH3)COO)2Mg], zinc acrylate [(CH2xe2x95x90CHCOO)2Zn], zinc methacrylate [(CH2xe2x95x90C(CH3)COO)2Zn], copper acrylate [(CH2xe2x95x90CHCOO)2Cu], copper methacrylate [(CH2xe2x95x90C(CH3)COO)2Cu], and the like. These metal-containing polymerizable monomers (xcex11) can be used alone or in combination of two or more suitably selected if necessary. Among them, zinc (meth)acrylate is preferable because due to high transparency of the resulting polymer product, hue of a film tends to be beautiful, and due to high solubility in a generally used organic solvent, productivity of a resin tends to be excellent.
As a method of producing the metal-containing polymerizable monomer (xcex11) having two unsaturated groups, a method is preferable in which an inorganic metal compound and a carboxyl group-containing radical polymerizable monomer are reacted together with water in an organic solvent containing an alcohol-based compound. The reaction product containing the (xcex11) component obtained in this method is excellent in compatibility with the organic solvent and other constituent components (acrylic monomer and the like), and when this reaction product is used, polymerization for obtaining a divalent metal-containing resin (C) tends to become easy. In this case, the production is preferably so conducted that the water content during the reaction is from 0.01 to 30 wt %.
As R3 (organic acid residue) of the metal-containing polymerizable monomer (xcex12) of the general formula (II), there are listed, for example, those derived from monovalent organic acids such as monochloroacetic acid, monofluoroacetic acid, propionic acid, octylic acid, versatic acid, isostearic acid, palmitic acid, cresotinic acid, xcex1-naphthoic acid, xcex2-naphthoic acid, benzoic acid, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, quinolinecarboxylic acid, nitrobenzoic acid, nitronaphthalenecarboxylic acid, purvinic acid and the like. These can be appropriately selected and used, if necessary. Among them, fatty acid-based residues are particularly preferable because they tend to be able to maintain a film causing no cracking and peeling over a long period of time.
Specific examples of the metal-containing polymerizable monomer (xcex12) of the general formula (II) include magnesium monochloroacetate (meth)acrylate, zinc monochloroacetate (meth)acrylate, copper monochloroacetate (meth)acrylate, magnesium monofluoroacetate (meth)acrylate, zinc monofluoroacetate (meth)acrylate, copper monofluoroacetate (meth)acrylate, magnesium propionate (meth)acrylate, zinc propionate (meth)acrylate, copper propionate (meth)acrylate, magnesium octylate (meth)acrylate, zinc octylate (meth)acrylate, copper octylate (meth)acrylate, magnesium versatate (meth)acrylate, zinc versatate (meth)acrylate, copper versatate (meth)acrylate, magnesium isostearate (meth)acrylate, zinc isostearate (meth)acrylate, copper isostearate (meth)acrylate, magnesium palmitate (meth)acrylate, zinc palmitate (meth)acrylate, copper palmitate (meth)acrylate, magnesium cresotate (meth)acrylate, zinc cresotate (meth)acrylate, copper cresotate (meth)acrylate, magnesium xcex1-naphtoate (meth)acrylate, zinc xcex1-naphtoate (meth)acrylate, copper xcex1-naphtoate (meth)acrylate, magnesium xcex2-naphtoate (meth)acrylate, zinc xcex2-naphtoate (meth)acrylate, copper xcex2-naphtoate (meth)acrylate, magnesiumbenzoate (meth)acrylate, zinc benzoate (meth)acrylate, copper benzoate (meth)acrylate, magnesium 2,4,5-trichlorophenoxyacetate (meth)acrylate, zinc 2,4,5-trichlorophenoxyacetate (meth)acrylate, copper 2,4,5-trichlorophenoxyacetate (meth)acrylate, magnesium 2,4-dichlorophenoxyacetate (meth)acrylate, zinc 2,4-dichlorophenoxyacetate (meth)acrylate, copper 2,4-dichlorophenoxyacetate (meth)acrylate, magnesium quinolinecarboxylate (meth)acrylate, zinc quinolinecarboxylate (meth)acrylate, copper quinolinecarboxylate (meth)acrylate, magnesium nitrobenzoate (meth)acrylate, zinc nitrobenzoate (meth)acrylate, copper nitrobenzoate (meth)acrylate, magnesium nitronaphthalenecarboxylate (meth)acrylate, zinc nitronaphthalenecarboxylate (meth)acrylate, copper nitronaphthalenecarboxylate (meth)acrylate, magnesium purvate (meth)acrylate, zinc purvate (meth)acrylate, copper purvate (meth)acrylate, and the like. These metal-containing polymerizable monomer (xcex12) can be used alone or in combination of two or more appropriately selected if necessary. Among them, zinc-containing polymerizable monomers are preferable because due to high transparency of the resulting polymer product, hue of a film tends to be beautiful, and due to high solubility in a generally used organic solvent, productivity of a resin tends to be excellent.
As a method of producing the metal-containing polymerizable monomer (xcex12), a method is exemplified, for example, in which an inorganic metal compound, a carboxyl group-containing radical polymerizable monomer and non-polymerizable organic acid in an organic solvent containing an alcohol-based compound.
Combination of components (xcex11) and (xcex12) as the metal-containing polymerizable monomer (xcex1) is preferable because self polishing property of a film tends to be maintained for a long period of time, and sufficient degree of wasting of a film tends to be manifested. Among them, combination of zinc (meth)acrylate with fatty acid-based zinc (meth)acrylate is particularly preferable.
In the case of combination of components (xcex11) and (xcex12) as the metal-containing polymerizable monomer (xcex1), the molar ratio (xcex11/xcex12) of a component (xcex11) unit to a component (xcex12) unit in a copolymer is preferably 20/80 to 80/20. By controlling the ratio to 80/20 or less, film properties excellent in cracking resistance and close adherence tend to be obtained, and by controlling the ratio to 20/80 or more, sufficient self polishing property of a film tends to be maintained for a long period of time. The ratio is preferably from 30/70 to 70/30.
For example, by reacting an inorganic metal compound, a carboxyl group-containing radical polymerizable monomer and a non-polymerizable organic acid in an organic solvent, a monomer dissolved mixture containing a (xcex11) component and a (xcex12) component can be obtained. In this case, the amount of the non-polymerizable organic acid used is preferably from 0.01 to 0.95-fold mol base on the inorganic metal compound. By controlling the amount to 0.01-fold mol or more, there occurs a tendency that a solid reaction product which is not easily copolymerized with a radical polymerizable unsaturated monomer (xcex2) is not produced easily, and self polishing property and cracking resistance of an antifouling paint for a long period of time become excellent. By controlling the amount to 0.95-fold mol or less, antifouling ability of an antifouling paint for a long period of time tends to be excellent. More preferable lower limit is 0.3-fold mol, and more preferable upper limit is 0.7-fold mol.
As an organic solvent used for the preparing the metal-containing polymerizable monomer (xcex1), an organic solvent containing at least an alcohol-based solvent is preferably used. By use of such organic solvents, production stability of a metal-containing polymerizable monomer (xcex1) tends to be excellent. In this case, the content of an alcohol-based compound in the organic solvent is preferably 5 wt % or more. By controlling the content to 5 wt % or more, solubility of the reaction product into the solvent is improved, a metal-containing polymerizable monomer (xcex1) can be produced stably, and storage stability of a metal-containing polymerizable monomer (xcex1) becomes excellent. More preferably, the amount is 25 wt % or more. As the alcohol-based compound, for example, ethanol, isopropanol, butanol, propylene glycol monomethyl ether and the like are listed.
In the divalent metal-containing resin (C), the unit amount of a radical polymerizable unsaturated monomer (xcex2) is not particularly restricted, and preferably from 20 to 90 wt %. By controlling this amount to 20 wt % or more, flexibility and cracking resistance and peeling property of a film tend to be excellent. This amount is more preferably 50 wt % or more. By controlling this amount to 90 wt % or less, balance between cracking resistance and peeling property of a film and self polishing property for a long period of time tends to be excellent. This amount is more preferably 80 wt % or less.
As the specific examples of the radical polymerizable unsaturated monomer (xcex2), the same examples as the specific examples of the radical polymerizable unsaturated monomer (B) listed above are exemplified.
A method of producing the divalent metal-containing resin (C) is not particularly restricted, and for example, this resin can be produced by mixing the various monomers described above, and reacting this mixture in the presence of a radical initiator at a temperature from 60 to 180xc2x0 C. for 5 to 14 hours. As the polymerization method, an emulsion polymerization method, suspension polymerization method and the like can be adopted in addition to a solution polymerization method effected in an organic solvent. Particularly, a solution polymerization method using a general organic solvent such as toluene, xylene, methyl isobutyl ketone, n-butyl acetate, propylene glycol monomethyl ether, n-butanol or the like is advantageous from the standpoints of productivity and painting ability.
The amount of the divalent metal-containing resin (C) in the antifouling paint composition of the present invention is preferably from 15 to 25 wt %. By use in amounts in this range, there occurs a tendency that paint abilities such as cracking resistance and the like are maintained, and an antifouling agent in amount sufficient to maintain excellent antifouling ability can be compounded easily in an antifouling paint.
The compound (D) of the general formula (I) is a component which maintains an excellent antifouling effect in sea for a long period of time, and keeps self polishing property of a film even when copper oxide is compounded as an antifouling agent.
Examples of the compound (D) of the general formula (I) include ethylmercaptane, allylmercaptane, isopropylmercaptane, n-propylmercaptane, t-butylmercaptane, isobutylmercaptane, n-butylmercaptane, t-amylmercaptane, s-amylmercaptane, n-hexylmercaptane, t-octylmercaptane, n-octylmercaptane, t-nonylmercaptane, n-decylmercaptane, t-dodecylmercaptane, n-dodecylmercaptane, t-tetradecylmercaptane, t-hexadecylmercaptane, stearylmercaptane, 2-mercaptoethanol, 2-mercaptoethyl octanoate, methyl thioglycolate, octyl thioglycolate, methoxybutyl thioglycolate, methyl mercaptopropionate, octyl mercaptopropionate, methoxybutyl mercaptopropionate, tridecyl mercaptopropioonate, cyclohexylmercaptane, 2-mercaptonaphthalante, 4-mercaptopyridine, thiosalicylic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, butanediol bisthioglycolate, ethylene glycol bisthioglycolate, trimethylolpropane tristhioglycolate and the like. These can be used alone or in combination of two or more appropriately selected if necessary. Among them, use of n-dodecylmercaptane, t-dodecdylmercaptane, n-propylmercaptane, n-octylmercaptane and the like of the general formula (I) in which R1 represents an alkyl group is preferable because cracking resistance of a film tends to become excellent. From the standpoint of odor of a film, n-dodecylmercaptane is particularly preferable.
In the case of use of 2-mercaptonaphthalene, 2-mercaptopyridine and the like of the general formula (I) in which R1 has a ring structure such as phenyl and the like, a plasticizer is preferably used together for suppressing cracking of a film.
In the case of use of 3-mercaptopropionic acid, ethylene glycol bisthioglycolate, 2-mercaptopyridine, 4-aminothiophenol and the like of the general formula (I) in which R1 contains a carboxyl group, thiol group or amino group, an alkyl acid is preferably used together for improving storage stability.
In the antifouling paint composition of the present invention,-the proportion of the compound (D) of the general formula (I) is preferably from 0.01 to 0.99-fold based on the metal content (mol number) contained in the divalent metal-containing resin (C). By controlling the proportion to 0.01-fold or more, there occurs a tendency that an excellent antifouling effect in sea can be maintained for a long period of time, and self polishing property of a film can be kept even when copper oxide is used as an antifouling agent. This proportion is preferably 0.1-fold or more. By controlling the proportion to 0.99-fold or less, there occurs a tendency that increase in viscosity in producing an antifouling paint is suppressed, and de-foaming property in painting and cracking resistance of a film tend to become excellent. This proportion is more preferably 0.9-fold or less, further preferably 0.8-fold or less.
The copper oxide (E) has a function as an antifouling agent. It is desirable that the copper oxide (E) is contained in a proportion usually from 25 to 1500 parts by weight based on 100 parts by weight (solid content) of the divalent metal-containing resin (C). By controlling this proportion to 25 parts by weigh or more, excellent antifouling for a long period of time tends to be obtained. This proportion is more preferably 150 parts by weight or more. By controlling the proportion to 1500 parts by weight or less, cracking resistance of a film tends to be excellent. This proportion is more preferably 500 parts by weight or less.
In the antifouling paint composition of the present invention, other compounds can also be compounded as an antifouling agent, if necessary, together with the copper oxide (E). As the specific examples of other compounds, the same compounds as listed previously as the specific examples of an antifouling agent are listed. Among them, zinc 2-pyridinethiol-1-oxide is preferable because they show a tendency of more excellent antifouling effect.
Other materials compounded, if necessary, into this antifouling paint composition, and methods of forming a film are the same as in another antifouling paint composition of the present invention explained previously.
The following examples and comparative examples illustrate the present invention further in detail, but do not limit the scope of the present invention. In the following descriptions, xe2x80x9cpartsxe2x80x9d are by weight.

Metal-containing monomer dissolved mixture, metal-containing resin and antifouling paint composition


The novel method relates to dyeing a textile article with medicinally rich herbs to produce natural, unique, deep and fast coloured textile articles having medicinal effects shield the human skin. Successive stages of dyeing include desizing, bleaching, scouring, galling, mordanting, dyeing, washing, colour fixing and finishing. The textile article is pretreated with camel/buffalo/cow dung, Myrobalans and Alum for fixation and development of colour and finally with extract of herbs for dyeing. Salts of copper, chromium, tin and iron can also be use as mordants to modify the shade. In yarn dyeing, drying is done by hanging on a bamboo stick in sunlight and for even penetration of dye yarn is continuously rotated in a dye solution. Novel herbal dyes, methods and cloths made thereof, in chemical free, detergent free, non hazardous, eco friendly, pollution free, having anti-allergic, antiseptic and antimicrobial functions are disclosed.

The principal object of this invention is to make not only eco friendly textiles but to impart other medicinal values of herbs along with natural colour of that herbs. Since dyeing is done by not only extracting colour alone from the herbs, but other medicinal ingredients of herbs are also imparted on textile articles with colour. This makes the textile article unique with not only natural colour of herb, but also having other medicinal value of herbs on that textile article.
Practically human body is 24 hrs in contact with some or other textile article in day to day life. Therefore it should be important that textile should not be harmful to human body in any ways.
The present invention comprise of; novel method of dyeing the textile article from medicinally rich herbs is 100% natural and not a single
synthetic chemical is used in dyeing the cloth. The principal object of this invention is to make more environment friendly textile material, moreover as the cloths are in touch with human body for 24 hours, it should not be harmful to the human body, not only that but it prevents and also cures number of diseases.
Presently in the textile market, synthetic chemicals are being used to dye the textile articles. In most of the textile Mills for dyeing, the article is processed under Machine; however, at small extent hand-operated dyeing is also adopted. In dyeing process, either the yarn or gray cloth is passed through the different stages. The stages are Desizing, Bleaching, Scouring, Mordanting, Dyeing, Washing, Colour Fixing, Finishing the dyed material. Colours used for dyeing are obtained from synthetic chemicals or from vegetables plants along with chemicals to fix the dye.
Japanese Patent Kokai Publication No. 234988/1990 discloses a dyeing process employing shiitake (a variety of mushroom, cortinellus shitake) which comprises boiling shitake to extract a colour principle, dyeing a fabric with the extract and developing and fixing the colour with a mordant.
Conventional chemical dyeing process developed about 80 years back. About 8000 hazardous chemicals are involved in conventional dyeing process. The tradition of dyeing the textile article with chemicals, was started in Germany & Switzerland, after that slowly it was continuously used world wide. The waste material of dyeing and printing, containing hazardous chemicals is dispatched in environment after finishing the process. Which pollutes the environment and natural resources by polluting soil, water & air. Which may be a source of some Skin related problems, Respiratory diseases, Cancer etc. Universally synthetic chemicals used to impart colours in fabric & yarn may invite harmful causative diseases, due to direct touch of chemicals with skin & directly transmit the same into human body.
In conventional chemical dyeing, the chemical structure constitute amines, amongst which cancer producing 42 amines or chemicals may be present. These cancer producing chemicals (amines) when exposed to the environment, enter into human body via skin, respiration or other transportal route; which may cause Skin Cancer, Throat Cancer, Blood Cancer and many of other Cancer along with skin related diseases.
Chemical dyed cloths are not advisable for Children, Pregnant Woman & Handicap, because it is most allergic to skin, hampers body respiration, is cancerous and Septic. In conventional dyeing process, chemicals used once to dye the cloths are repeatedly used for further dyeing to make colour bright & fast.
Ten years back Eco-friendly and vegetable dyeing process started in market to compete with the Chemical dyeing process. Comparatively it has achieved a remarkable height. Eco-friendly dyeing process is less hazardous & beneficial as compare to conventional chemical dyeing. About 8000 chemicals are still in use for eco friendly dyeing but with restricted parameters. The process is totally machine based and does not harm the natural form of life & environment if followed as per norms. Amines are an important constituent of chemical structure, of which 22 banned cancerous amines excluded from the process. Azo free eco friendly dyeing process is presume to be less hazardous than conventional chemical dyeing. Thus it is Non Allergic, Non Cancerous, does not affect Body Respiration to that extent; hence advisable for Children, Pregnant woman and Allergic patients. However, degradable detergents are used to remove the dirt from cloths before dyeing process.
To overcome these problems the new concept of dyeing the cloths is used to achieve the best results.

Method of dyeing the textile article from medicinally rich herbs


The present invention discloses an image capturing device and an image synthesis method thereof. The image capturing device comprises an image capturing module, an exposure module, and a processing module. The image capturing module captures a high bit-depth scene image corresponding to a scene. The exposure module meters the light of the scene to generate a plurality of histograms. The processing module calculates a plurality of discrete values of different exposure conditions of the high bit-depth scene image based on the plurality of histograms, processes the high bit-depth scene image to generate at least two low bit-depth temporary images in different brightness conditions based on at least two highest discrete values, and synthesizes the at least two low bit-depth temporary images in different brightness conditions to generate a high dynamic range image.

High dynamic range (HDR) file is a special image file format and each pixel comprises the information of RGB and the real brightness of the point. Generally, the grey scale of each pixel of the image file ranging only from 0 to 255 is not enough because the difference between the brightness scale/grey scale of the sun and a black object is much more than 256. The cloud and the sun in a common daytime scene image might be presented in the same grey scale/brightness scale (as pure white), but in fact there is a huge difference between the brightness scale of the cloud and the sun. Thus, the common image file format doesn't precisely record the true situation in the real world.
High dynamic range refers to the relative ratio between the lightest and darkest area of a scene. The brightness of the actual scene recorded by the high dynamic range image is over than 256 levels but the area which exceeds can't be seen on the display. For example, while opening an image with the scene from the indoor to the outside of the window in Photoshop, the outside area of the window shows a plenty of white color without many details due to the overexposure. Dimming the light won't show more details but only turn the white color into the grey color. If the same scene is recorded as the high dynamic range image, reducing the exposure will be able to presents more details in the area previously shown as the white color.
The traditional method of high dynamic range image synthesis usually uses the fixed exposure values to shoot several images of the same scene. Images in different exposure conditions are combined to integrate the image dynamic status of the scene, and the difference of the exposure value of each image ranges from 1 to 2 exposure compensations or fewer. Because the dynamics of each image is limited, such traditional method requires more images to synthesize the high dynamic range image. A common camera can not process more than three images in the short period due to the limited processing capability. Therefore, the present technology selects two or three images with fixed exposure compensation to synthesize the high dynamic range image. However, an expected high dynamic range image can't always be retrieved because the appropriate exposure compensation value of the scene can not be set for image shooting or image processing. Thus, developing an ideal image capturing device and an image synthesis method to synthesize a high dynamic range image is an emerging issue in the market.

This patent is subject to a terminal disclaimer.

Image capturing device and image synthesis method thereof


A method of treating a patient with an ailment, comprises delivering first energy to a dorsal root ganglia (DRG), thereby modulating the DRG, and delivering second energy to at least one of a central neural axon extending from the DRG and a peripheral neural axon extending from the DRG, thereby modulating the at least one of the central neural axon and the peripheral neural axon.

Among many techniques attempted for neurostimulation (e.g., electrical, chemical, mechanical, thermal, magnetic, optical, and so forth), electrical stimulation is the standard and most common technique. Implantable electrical stimulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) techniques, which directly stimulate the spinal cord tissue of the patient, have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of spinal cord stimulation has begun to expand to additional applications, such as angina pectoralis and incontinence. Deep Brain Stimulation (DBS) has also been applied therapeutically for well over a decade for the treatment of refractory chronic pain syndromes, and DBS has also recently been applied in additional areas such as movement disorders and epilepsy. Further, Functional Electrical Stimulation (FES) systems such as the Freehand system by NeuroControl (Cleveland, Ohio) have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients. Occipital Nerve Stimulation (ONS), in which leads are implanted in the tissue over the occipital nerves, has shown promise as a treatment for various headaches, including migraine headaches, cluster headaches, and cervicogenic headaches. In recent investigations, Peripheral Stimulation (PS), which includes Peripheral Nerve Field Stimulation (PNFS) techniques that stimulate nerve tissue directly at the symptomatic site of the disease or disorder (e.g., at the source of pain), and Peripheral Nerve Stimulation (PNS) techniques that directly stimulate bundles of peripheral nerves that may not necessarily be at the symptomatic site of the disease or disorder, has demonstrated efficacy in the treatment of chronic pain syndromes and incontinence, and a number of additional applications are currently under investigation. Vagal Nerve Stimulation (VNS), which directly stimulate the Vagal Nerve, has been shown to treat heart failure, obesity, asthma, diabetes, and constipation.
Each of these implantable stimulation systems typically includes at least one stimulation lead implanted at the desired stimulation site and neurostimulator (e.g., an implantable pulse generator (IPG)) implanted remotely from the stimulation site, but coupled either directly to the electrode lead(s) or indirectly to the stimulation lead(s) via a lead extension. Thus, electrical pulses can be delivered from the neurostimulator to the stimulation lead(s) to stimulate or activate a volume of neural tissue. In particular, electrical energy conveyed between at least one cathodic electrode and at least one anodic electrode creates an electrical field, which when strong enough, depolarizes (or "stimulates") the neurons beyond a threshold level, thereby inducing the firing of action potentials (APs) that propagate along the neural fibers. The stimulation regimen will typically be one that provides stimulation energy to all of the target tissue that must be stimulated in order to provide the therapeutic benefit, yet minimizes the volume of non-target tissue that is stimulated.
The stimulation system may further comprise a handheld remote control (RC) to remotely instruct the neurostimulator to generate electrical stimulation pulses in accordance with selected stimulation parameters. The RC may, itself, be programmed by a technician attending the patient, for example, by using a Clinician's Programmer (CP), which typically includes a general purpose computer, such as a laptop, with a programming software package installed thereon. If the IPG contains a rechargeable battery, the stimulation system may further comprise an external charger capable of transcutaneously recharging the IPG via inductive energy.
Recently, there has been an interest in stimulating dorsal root ganglia (DRG) for the treatment of chronic pain. The DRG is a nodule that contains cell bodies of neurons in afferent spinal nerves, and in particular, dorsal root (DR) nerve fibers. Afferent spinal nerves provide sensory information, such as touch, pain, heat/cold, and proprietary sensation, which is propagated by action potentials that travel along the nerve fibers.
As shown in FIG. 1, a DRG 1 comprises cell bodies 2 (or somas) that include axon branches projecting to central and peripheral targets. In particular, each cell body 2 is typically connected to a stem neural axon 3 that is branched to a central neural axon 4 (i.e., a spinal nerve) that extends to the spinal cord, and a peripheral neural axon 5 that extends to a peripheral region of the body. The positioning of the cell body 2 is somewhat midway between the central neural axon 4 and the peripheral neural axon 5, and thus, may be called "pseudounipolar."
Traditionally, a cell soma provides metabolic support, but DRG soma are known to undergo subthreshold depolarization when neighbor soma are invaded with afferent spikes. This means that some degree of cross-talk between the cell bodies can occur in the DRG. In healthy DRG, these interactions tend to be causal, in that regular afferent activity will generate subthreshold oscillations and some spiking while the afferent signaling is present, but rarely when sensory neurons are quiet. In pathological states, such as those following nerve injury or trauma, it is believed that the DRG soma become hyperactive, such that they generate enhanced periodic subthreshold membrane oscillations, often independent of afferent activity. In the hyperactive state, the soma have increased metabolic needs, and these needs may lead to oxygen debt and reduced mitochrondrial performance with the sensory neurons. This, in turn, can lead to ectopic electrical spiking within the sensory neurons. The action potentials resulting from the ectopic electrical spiking then feed into the dorsal horn laminae and are believed to hypersensitize these neural structures. This hypersensitization may then lead to chronic pain.
It is known to electrically stimulate the DRG to treat chronic pain. However, stimulating only the DRG may have limited effects in treating chronic pain.
There, thus, remains a need to provide a more effect technique for treating chronic pain.

Electrical stimulation method for modulation on sensory information around dorsal root ganglia

Boston Scientific Neuromodulation Corporation


A user at a receiving Web station is provided with several alternate Web page display interface formats, from which the user may select the appropriate format for each Web document that he bookmarks. Thus, each time that a bookmarked Web document will be displayed subsequently, it will have this optimum presentation interface format. The implementation comprises bookmarking a received Web document, predetermining at least one display interface format alternate to said standard display interface format for bookmarked Web documents, providing a document folder associated with each alternate display interface format, enabling a user to put a bookmarked Web document into a document folder associated with an alternate display interface format and displaying bookmarked documents in said document folder in said alternate display interface format.

The past decade has been marked by a technological revolution driven by the convergence of the data processing industry with the consumer electronics industry. The effect has, in turn, driven technologies that have been known and available but relatively quiescent over the years. A major one of these technologies is the Internet or Web (the two terms are used interchangeably) related distribution of documents, media and programs. The convergence of the electronic entertainment and consumer industries with data processing exponentially accelerated the demand for wide ranging communications distribution channels, and the Web or Internet, which had quietly existed for over a generation as a loose academic and government data distribution facility, reached "critical mass" and commenced a period of phenomenal expansion. With this expansion, businesses and consumers have direct access to all matter of documents, media and computer programs.
In addition, Hypertext Markup Language (HTML), which had been the documentation language of the Internet or Web for years, offered direct links between pages and other documentation on the Web and a variety of related data sources that were at first text and then evolved into media, i.e. "hypermedia". This even further expanded the use of the Internet or Web. Although many Web pages are professionally designed and, thus, relatively efficient to use, there are still a great many Web pages that are poorly designed and, thus, may present a cumbersome and confusing display interface when presented to the receiving user on the standard Web browser display interfaces, e.g. GUIs (graphical user interfaces). Web browsers that have been available for over a decade as a Web document search and access tool have provided users with the means of bookmarking, i.e. saving the Web path to such documents for future reference. However, such bookmarked Web documents are presented to the receiving user in a standard all-purpose display interface that serves as a default interface. The receiving user may predetermine the values of the attributes that define this interface, and these will serve as the user's standard or default interface. Of course, as the user receives specific Web documents, he is free to change the attribute values from the default values for any specific document display. This is relatively inefficient and time consuming to do Web document by Web document.
On the other hand, the user may need to present different types of regularly accessed, i.e. bookmarked, Web documents in different formats. For example, the user may wish to view a newspaper Web page in a different format from his stock portfolio page or job related technical Web page. Consequently, there is a need to provide Web page users with the means for effectively displaying bookmarked Web documents in different interface formats.

World wide web document distribution system with a plurality of alternate user-interface formats selectively available for each bookmarked web document

International Business Machines Corporation


A control system for a homogeneous charge compression ignition (HCCI) engine includes first and second modules. The first module determines a load on the HCCI engine when the HCCI engine is operating in an HCCI combustion mode. The second module controls torque generated by the HCCI engine based on the determined load and a predetermined threshold, wherein the second module controls the torque generated by the HCCI engine by controlling fueling of the HCCI engine.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. Air flow into the engine is regulated via a throttle. More specifically, the throttle adjusts throttle area, which increases or decreases air flow into the engine. As the throttle area increases, the air flow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders and/or to achieve a desired torque output. An ignition timing control system adjusts the spark timing in order achieve the optimized spark timing for desired torque. Increasing the amount of air and optimizing fuel and spark timing provided to the cylinders increases the torque output of the engine. Engine control systems have been developed to control engine output torque to achieve a desired torque and also rapidly or immediately change torque levels.

System and method for torque control in a homogeneous charge compression ignition engine


A integrated circuit includes a processor, a bus coupled to the processor, a memory interface and an interface bus. The memory interface provides an interface between the bus and at least two memory devices including a first memory device and a second memory device. The interface bus is coupled to the first memory device, the second memory device and the memory interface. Control signals, address signals and data signals are transmitted over the interface bus.

The present invention relates to the field of integrated circuits. More particularly, the present invention relates to techniques for interfacing integrated circuits to external memory.
Processing systems generally include a central processing unit (CPU), logic, internal memory, and a system bus coupling the CPU, logic and internal memory. It is often necessary in processing systems to interface the system bus with external memory. The external memory may include static memory, such as flash memory, or dynamic memory such as synchronized dynamic random access memory (SDRAM).
One approach to interfacing a processor system to an external memory includes using a memory interface. In a programmable or configurable system on a chip, a memory interface having programmable input/output pins (PIO) may be used. The PIO pins of the memory interface are programmed to be used as address or data lines for the external memory. The unused address and data lines are used as user-defined PIO pins. PIO pins are expensive, however, so that it is necessary to preserve as many pins as possible for the user. If more than one external memory needs to be interfaced with a memory interface of a processor system, fewer pins are available for use by the user.
A integrated circuit is described. In one embodiment, the integrated circuit includes a processor, a bus coupled to the processor, a memory interface and an interface bus. The memory interface provides an interface between the bus and at least two memory devices including a first memory device and a second memory device. The interface bus is coupled to the first memory device, the second memory device and the memory interface. Control signals, address signals and data signals are transmitted over the interface bus.
Other features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows below.

Method and system for interfacing an integrated circuit to synchronous dynamic memory and static memory


A test fixture for electronic circuit boards includes a contact carrier plate and a pressure plate. The contact carrier plate is provided with contact pins projecting through holes of the pressure plate, in order to contact a circuit board to be tested. Upon the appliance of vacuum, the pressure plate, together with the circuit board under test, is sucked against the contact pins. The invention provides essentially flat contact between the circuit board under test and the pressure plate. For this purpose, no seal rests on top of the pressure plate, or at least a resilient seal which is completely compressed upon the appliance of vacuum. The invention demonstrates that, in contrast to the prior art, it is thus possible to achieve sufficient sealing.

Test fixtures of the type described above are needed in order to test the operation of loaded electronic circuit boards. For example, tests can be made to determine whether a specified resistance value is present between two terminals, or whether an error in component loading has been made. The signal patterns of digital circuits and other electronic components can also be tested in this context. At the same time, the test ensures that the specified conductor paths are all present and conductive. One typical defect that occurs in the manufacture of electronic circuit boards consists of hairline cracks in conductor paths that cannot be detected by visual inspection, but that interrupt electrical signal flow. Such hairline cracks can be reliably detected with a test fixture of the kind mentioned above.
The test fixture is also suitable for testing unloaded circuit boards, insofar as only the electrical conductivity of the conductor paths is an issue.
One essential prerequisite for test fixtures of this kind is that the circuit boards under test must be replaceable quickly, so that a large number of circuit boards intended for delivery to customers can be tested with one and the same test fixture. Known test fixtures therefore include a so-called vacuum adapter to allow rapid contacting of the circuit board, and also allow quick detachment of the electrical connections. These known configurations provide for a contact carrier plate which holds electrical contact pins of a wide variety of types, for example with a press fit in corresponding holes. Arranged parallel to the contact carrier plate is a movable pressure plate that is provided with holes for the contact pins. The pressure plate (or support plate), for its part, carries the electronic circuit board under test. Upon the appliance of vacuum, the movable pressure plate, together with the circuit board under test, is pulled towards the contact carrier plate. As a result the contact pins pass through the holes in the pressure plate and contact the contact points provided on the circuit board under test, such that electrical contact is made and the testing process can begin.
It is understood that the contact carrier plate, rather than the pressure plate, can also be mounted in a movable fashion, or that both plates can be movable. What is important in this respect is only the relative movement of the two plates, so that the wording selected above also covers the case of a movable contact carrier plate. It is also understood that the contact carrier plate and the pressure plate must be adapted to the particular circuit board under test, since the contact points provided typically vary from one circuit board to another. It is therefore advisable, once a contact carrier plate and the corresponding pressure plate have been installed, to test a plurality of identical circuit boards with them. If a circuit board with a different function and/or geometry is to be tested, the contact carrier plate and the pressure plate must be replaced.
The crucial element that allows quick replacement of the circuit boards under test is therefore a vacuum source that pulls the contact carrier plate and the pressure plate towards one another, and thereby establishes electrical contact between the contact pins and the electronic circuit board under test.
One known problem of such vacuum adapters involves adequate sealing with respect to the atmosphere. If insufficient sealing is achieved here, the pressure plate will not be pulled to a sufficient extent towards the contact carrier plate, and the electrical contacts between the contact pins and the circuit board under test will not be established, or will be unreliable. The principal weak point in the necessary sealing is the circuit board under test. For example, if it cannot be achieved to prevent air from flowing over the edges of the circuit board through the holes in the pressure plate, then the desired level of vacuum between the contact carrier plate and pressure plate will be attained either incompletely or not at all.
Known test fixtures of the aforesaid type provide therefore a seal that seals the edges of the circuit board under test with respect to the atmosphere. Such a seal typically consists of a strip of silicone rubber or the like which is closed in itself and fastened on the pressure plate, wherein the edges (i.e., the outer regions of the bottom side) of the circuit board under test rest on said strip. A second strip of sealing material is placed on the first strip, and seals the flanges of the circuit board under test. One example of this kind of double seal is described in the manual entitled "HP 3070 Board Test System Users' Manual, Fixture for the HP 3070," (1990), page 8-3.
This manner of sealing the circuit board under test with respect to the atmosphere is extremely complex and costly. For example, the costs for producing a single silicone rubber seal are approximately 2000-3000 DM, since a mold hast to be produced, a casting has to be made etc. In view of the fact that the seal thus obtained can then be used only for a single pressure plate--in other words, only a single type of circuit board can be tested--it is evident that enormous costs can be incurred with a plurality of different circuit boards under test.
A further disadvantage of the known technology consists in the fact that the circuit board under test is arranged at a certain distance to the pressure plate, since the first sealing strip can only be made with a certain degree of resilience.
To prevent the circuit board from slipping off the step arranged between the first and the second sealing strip, and in order to prevent excessive deflection of the plate, test fixtures according to the prior art therefore have spacer blocks arranged on the upper surface of the pressure plate. The circuit board under test rests on these spacer blocks. However, the manufacture and application of the spacer blocks entails further costs. Moreover, a certain degree of deflection of the circuit board under test, namely between the individual spacer blocks, cannot be completely prevented. The circuit board is therefore subject to shear forces (or "board stress"), which in turn can cause defects such as the aforementioned hairline cracks.

Test fixture for electronic circuit boards


A hollow shaped socket insert adapter rotatively driven by a single socket driver for tightening, loosing, and removing various sizes of nuts/bolts.

Sockets are one of the most commonly used mechanical tools for driving nuts and bolts. Most of the earlier standard socket drivers were designed with specific metric or SAE size for fastening nuts/bolts thus each time a different socket driver was required for driving nuts/bolts of various dimensions and shapes. Some adjustable socket drivers having a movable jaw and a fixed jaw are available in the prior art to engage nuts/bolts of various dimensions and shapes but such socket drivers are not efficient to prevent rotation of nuts/bolts and do not offer grip to operate on different shapes and sizes of fasteners.
One of the common problem with inserts used in socket drivers of the prior art is the sharp corners which cause the spinning and slippage while providing torque to the inserts because of the improper locking between the insert and socket driver. The major drawback with existing split side, gap wall, and similar inserts available in the prior art is that they fail to provide the durability, strength, and efficiency for driving large diameter of nuts/bolts.
Thus, there is a longstanding need to design insert adapters which can be driven by a single socket driver efficiently to operate on a large range of nuts and bolts of different sizes and shapes.


A code generation apparatus (100) generates a plurality of spreading code sequences, using block encryption processing of outputting a plurality of blocks as a spreading code sequence (D). A parameter selection unit (130) acquires a sequence parameter (KP) uniquely corresponding to each spreading code sequence (D) of the of the plurality of spreading code sequences. A secret key acquisition unit (150) acquires a secret key (K). A code sequence generation unit (140) changes output data that is output from each of process elements, using the sequence parameter (KP), when the code sequence generation unit (140) generates each spreading code sequence (D) of the plurality of spreading code sequences by the block encryption processing using the sequence parameter (KP) and the secret key (K).

In recent years, various services using satellite communication or wireless communication have been provided. A spread spectrum system is used in these services in order to implement connectivity and confidentiality of the communication. There are a direct sequence spread spectrum system and a frequency hopping system in the spread spectrum system. In the direct sequence spread spectrum system, data communication is performed by spreading energy to frequencies wider than that of transmission data. In the frequency hopping system, communication is performed between a transmitting apparatus and a receiving apparatus by switching a frequency to a higher one according to a certain rule.
In the direct sequence spread spectrum system, a signal desired to be transmitted is spread to a wide band, using spreading code sequences. This causes the signal desired to be transmitted to have a characteristic of appearing like noise in the direct sequence spread spectrum system. This characteristic makes it difficult for the signal desired to be transmitted to be intercepted, thereby increasing jamming resistance. This makes it difficult for interference to a narrow band signal to occur in the direct sequence spread spectrum system. As mentioned above, the spreading code sequences in the direct sequence spread spectrum system are important for implementing reliable and secure transmission without causing high interference with a different signal.
In the direct sequence spread spectrum system that has been commonly used, use of each spreading code sequence having a short periodicity increases connectivity of communication. However, it becomes highly likely that the spreading code sequence having the short periodicity will be inferred by being observed for a certain period of time, so that confidentiality is low. However, it is necessary to increase the confidentiality in order to increase resistance against radio interference. Therefore, a method of lengthening the period of the spreading code sequence is used. Alternatively, a method of adopting spreading code sequences using confidential information that cannot be predicted by a third party is used. Patent Literature 1 discloses a method of using a chaotic sequence as a technology for enhancing confidentiality of a spreading code sequence.
Patent Literature 1 discloses a method of generating chaotic spreading codes that are suitable for a satellite navigation system and a CDMA (Code Division Multiple Access) communication system. Patent Literature 1 discloses that the spreading codes generated by using the chaotic sequence have autocorrelation and cross-correlation properties and improve confidentiality. The confidentiality that is achieved by the spreading codes generated by using the chaotic sequence indicates randomness including pseudo randomness. The confidentiality that is achieved by the spreading codes generated by using the chaotic sequence, however, does not indicate strict security which is given when a cryptographic technology is used. Further, in order to perform spread spectrum communication that is highly confidential by using the spreading codes generated by using the chaotic sequence, establishment of chaotic sequence synchronization is necessary. Patent Literature 1, however, does not disclose an effective method for the establishment of the synchronization.
Each of prior arts from Patent Literatures 2 to 7 discloses a method of achieving confidentiality improvement by using a chaotic sequence. Each of the prior arts from Patent Literatures 2 to 7, however does not disclose an effective method for establishment of chaotic sequence synchronization.
As an effective method for establishment of chaotic sequence synchronization, a method of using a CTR (Counter) mode of an n-bit block encryption algorithm may be considered.

Code generation apparatus, code generation method, and computer readable medium


An aircraft has a vertical fin fastened to the rear and above a fuselage of elongated form, essentially in a vertical plane of symmetry of the aircraft. The vertical fin has at least two stable positions, an extended position and a returned position, such that a surface of the vertical fin, subjected to an aerodynamic flow when the aircraft is in flight, is modified in position or in surface between the returned position and the extended position, so that the aerodynamic drag of the vertical fin is reduced in the returned position under given flight conditions compared to the extended position. The change from one surface to another of the vertical fin is accomplished by modifying the geometry of the vertical fin or by displacing the vertical fin relative to the fuselage so that the vertical fin, for example, is more or less inside the fuselage, or more or less immersed in the wake zone of the fuselage in which the local dynamic pressure Pd is reduced relative to the infinitely upstream dynamic pressure Pd0.

1. Field
This invention relates to the field of aircraft such as civil transport aircraft.
More particularly, the invention relates to an aircraft that has at least one vertical fin fastened to the fuselage in a rear area of the fuselage, the geometric configuration of which is modified to reduce drag while cruising.
2. Brief Description of Related Developments
Modern transport aircraft, in particular civil passenger transport aircraft, at least for the most widely used aerodynamic architectures, have a group of fins fastened at the rear of a main aircraft structure that itself includes a vertical fin, most often fastened to the fuselage and above it, essentially in a vertical plane of symmetry of the aircraft.
The vertical fin has a dual role.
On the one hand, by virtue of the aerodynamic forces that it generates on the aircraft, the vertical fin assures a natural directional stability of the aircraft.
This directional stability is due to the restoring torque Cn around a vertical axis Z of a conventional aircraft configuration when the aircraft is subjected to an aerodynamic sideslip β, in other words the aerodynamic coefficient Cnβ=dCnβ/dβ is negative and tends to cancel the sideslip. The torque Cn originates from a lateral lift along Y of the vertical fin when the aerodynamic sideslip β is not zero.
On the other hand, by means of a directional rudder, in other words an aerodynamic surface hinged to the trailing edge of the vertical fin, the vertical fin is able to generate a yawing torque that is a function of the setting of the directional rudder, proportional to a first approximation to the angle of the rudder setting.
This rudder is used to direct the aircraft when the flight conditions are not symmetrical on the aerodynamic level.
Such asymmetric flight situations are encountered when the aircraft is subjected to lateral aerodynamic flow, for example in the presence of gusts of wind that have a horizontal component and especially when the aircraft is in a dissymmetric propulsive engine thrust configuration, essentially in case of an engine breakdown.
In these asymmetric configurations, a more or less durable action on the directional rudder is necessary to assure the control of the aircraft in flight or on the ground, and the efficacy of the control depends on the dimensions in particular of the reference aerodynamic surfaces of the vertical fin and of its rudder, as well as on the geometry of the fin following the known effects of parameters such as elasticity, deflection, or others.
In practice, the aerodynamic forces generated by the vertical fin are directly proportional to the dynamic pressure Pd of the aerodynamic flow, in other words it is a function of the square of the airspeed of the aircraft: Pd=½ ρV2, ρ being the density of the air at the point of flight under consideration, and V being the relative speed between the aircraft and the flow.
In practice, the dimensions of the vertical fin, both of its fixed part and of its rudder, are most often established for the most unfavorable flight conditions, in other words at low speed when the dynamic pressure Pd is low and when the dissymmetry of flight is at a maximum, which occurs in general when the thrust of the engines is maximal with failure of an engine off center relative to the plane of symmetry of the aircraft, with the ability of the aircraft to control its trajectory then defining a minimum control speed VMC,
The summation of these two condition (low dynamic pressure and dissymmetry) is encountered effectively in case of an engine failure during a low-speed phase of flight, at takeoff or when restoring gas on approach, in flight or on the ground during an acceleration, when the speed no longer assures the lateral control of the aircraft by acting on the wheels, and taking this critical condition into account imposes a vertical fin of large dimensions even though when the speed is higher than during the takeoff or approach phases, a vertical fin of relatively smaller dimensions would be sufficient to assure correct directional stability.
The vertical fins of current aircraft accordingly have dimensions determined for critical conditions that concern only a limited period of the flight of an aircraft, and have dimensions greater than those needed for the longer period of flight, which is penalized in particular considering a traversed surface of no use in the aerodynamic flow, that generates aerodynamic drag.

Airplane with a modifiable surface of vertical empannage


A leapfrog filter comprising a first and a second integrator each consisting of an operational amplifier and integrating capacitor. The leapfrog filter includes differential amplifier which is arranged to differentially supply current to the first and second integrators through a first and a second current source circuit respectively; and a third current source circuit for adjusting the sum of currents supplied to the first and second current source circuits, wherein characteristics such as the center frequency f.sub.o and quality factor Q of the leapfrog filter are controlled by adjusting the respective current values.

1. Field of the Invention
This invention relates to a leapfrog filter, and more particularly it pertains to such a filter which is so designed that adjustment of the quality factor Q and center frequency f.sub.0 of the filter characteristics is facilitated.
2. Description of the Prior Art
Referring to FIG. 1, description will first be made of an example of conventional active filter, which is constructed in the form of biquad circuit constituting a low-pass filter. The transfer function T(S) of a common low-pass filter is given as follows: ##EQU1## where .omega..sub.0 is angular frequency; s is complex variable; Q is loss factor of coil; and H is gain factor.
The relationship between input and output voltages V.sub.1 and V.sub.2 of the biquad circuit can be expressed in the form of transfer function T(S) as follows: ##EQU2##
Assuming that the factor of each term in Equation (1) and that in Equation (2) are equal to each other, the angular frequency .omega..sub.0 and quality factor Q are given as follows: EQU .omega..sub.0.sup.2 =1/R.sub.3 R.sub.4 C.sub.1 C.sub.2 ( 3) EQU Q=(R.sub.1.sup.2 C.sub.1 /R.sub.2 R.sub.4 C.sub.2).sup.1/2 ( 4)
As will be seen from Equations (3) and (4), it is required that circuit constants such as resistors R.sub.1 to R.sub.4 or capacitors C.sub.1 and C.sub.2 be made variable to make variable the center frequency f.sub.0 and quality factor Q. With biquad circuit, to make variable the center frequency f.sub.0 and quality factor Q, externally mounted components are used as the resistors R.sub.1 to R.sub.4 or capacitors C.sub.1 and C.sub.2, and the filter characteristic is adjusted by changing the circuit constants. With the conventional active filter such as biquad circuit, it has been the usual practice that a number of components such as operational amplifiers resistors, capacitors and so forth are hybrid-integrated on a hybrid substrate.
However, the conventional active filter such as shown in FIG. 1 is disadvantageous in that the manufacturing cost is high because a number of components are needed. Another disadvantage is such that when it is attempted to adjust the center frequency f.sub.0 and quality factor Q of the filter, it is required that such adjustment be effected with components having different circuit constants being mounted on a printed circuit board in accordance with the desired filter characteristic.

Leapfrog filter having adjustable center frequency and quality factor