An ESCAP type polymer which has a controlled structure wherein the groups protecting phenolic hydroxyl groups have been selectively or partly eliminated or decomposed with an acid and no carboxylic acid residues are contained and which is a narrow-disperse polymer and is suitable for use as a material for a chemical amplification type resist for excimer lasers which has excellent resolution. The process is characterized by subjecting either an alkenylphenol in which the phenolic hydroxyl group has been protected or the alkenylphenol and a vinylaromatic compound to anionic polymerization together with a (meth)acrylic ester to give a block copolymer and eliminating only a given proportion of the groups protecting the phenolic hydroxyl groups from the block copolymer with an acid reagent. Thus, an alkenylphenol copolymer is synthesized which has a ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), (Mw/Mn), of 1.00 to 1.50 and has no carboxylic acid residues.

The present invention relates to narrow-disperse alkenylphenol copolymers that have not known yet and to processes for the preparation of the same. In more detail, it relates to narrow-disperse alkenylphenol copolymers that have controlled structures and with alkenylphenol units, alkenylphenyl ether units and (meth)acrylic ester units as essential constituent units, and to processes for the preparation of the same. The alkenylphenol copolymers of the present invention have expectations to be used as resist materials for excimer lasers.
Alkenylphenol copolymers useful as resist materials have been well known so far. For example, Japanese Patents Laid-open Nos. Hei 4-211258, 7-209868, 7-49569, 9-160244 and 11-125907 describe random copolymers containing repeating units represented by Formulae (I), (II) and (III). Japanese Patent Laid-open No. Hei 11-125907 describes positive-type radiation-sensitive resin compositions that have, as constituents, resins insoluble or hardly soluble in alkali and protected with groups to be dissociated with acids. The resins become soluble in alkali when the said acid dissociating groups are dissociated. It describes, as constituent units of the said resins, random copolymers or block copolymers each having constituent units represented by Formula (IV) (wherein, R13 and R14 are each independently hydrogen or methyl, and R15 is hydrogen, t-butoxy or another group).
Japanese Patent Laid-open No. Hei 10-265524 describes a polymer compound having a repeating unit represented by Formula (VII) shown below (wherein, R is hydroxyl or OR20, and R20 is a group unstable to acids). The polymer is cross-linked by a cross-linking group with an intramolecular and/or intermolecular Cxe2x80x94Oxe2x80x94C groups that are obtained by a reaction of part of the phenolic hydroxyl group and/or carboxyl group, which are represented by R of Formula (VII), with an alkenyl ether compound or halogenated alkyl ether. The polymer has the weight-average molecular weight of 1,000 to 500,000, with the total amount of the said acid-unstable groups and cross-linking groups at a ratio exceeding 0 mole% and less than 80 mole% of the average of the whole phenolic hydroxyl and carboxyl groups.
Japanese Patent Laid-open No. Hei 10-53621 describes polymers having a structure represented by Formula (VIII) (wherein, R21 is hydrogen or lower alkyl, R23 and R24 are hydrogen, alkyl optionally substituted with halogen or another, R25 is alkyl optionally substituted with halogen or another, and R26 is carboxyl optionally substituted with alkyl or another), with dispersibility of more than 1 and less than 1.5.
Homopolymers and copolymers of alkenylphenols, represented by poly-p-hydroxystyrene and the like, are useful as materials for chemical amplification type resists for excimer lasers. Among them, particularly resists produced using copolymers consisting of hydroxystyrenes and acrylic esters are known as so-called ESCAP type resists able to give higher resolution.
In this field, technology to make resolution higher has been advanced remarkably, and higher resolution is always looked for. A desirable structure for the ESCAP type polymers to realize higher resolution is a structure with groups that protect part of the alkenylphenol portions and are eliminated and/or decomposed with acids produced when the groups are exposed to light. Besides, a desirable polymer has a narrow molecular distribution and a controlled structure. This kind of structure controls unnecessary, excessive diffusion of acids generated from photoacid generators of a resist composition, and the solubility of the phenolic hydroxyl or carboxyl groups is controlled so as not to dissolve excessively in alkali developers. Thanks to these effects, the obtained polymer is expected to be a resist material to contribute to make resolution higher.
Many of ESCAP type polymers with such structures and which have been reported so far are synthesized by radical polymerization, and are not satisfactory because of the dispersibility (Mw/Mn) of more than 1.50. The said Japanese Patent Laid-open No. Hei 10-265524 has disclosed an ESCAP type polymer having a narrow molecular distribution and a controlled structure. The polymer is unsatisfactory, however, because the ester portion as a protecting group is a group that is not eliminated with an acid, such as methyl, or that has a carboxylic acid residue. With such an ester structure, it is difficult to make solubility in an alkali developer different between an area exposed to light and that not exposed. Besides, a method is applied of introducing the said group protecting the hydroxyl or carboxylic acid group partially at a later stage. Because of it, there is a problem of difficulty to completely protect particularly the carboxylic acid portions in the polymer.
The said Japanese Patent Laid-open No. Hei 11-125907 describes random copolymers or block copolymers, but has no description of synthetic methods and molecular distributions of these polymers. The said Japanese Patent Laid-open No. Hei 10-53621 has disclosed ESCAP type polymers with narrow dispersibility, but actually described only random copolymers, which were not satisfactory as materials for high resolution resists.
It is an object of the present invention to provide narrow-disperse, ESCAP type polymers that do not contain carboxylic acid residues, have controlled structures, and have groups protecting phenolic hydroxyl groups and being eliminated and/or decomposed with acids selectively and partially.
The inventors of the present invention have studied in earnest to accomplish the above object and found that block copolymerization consisting of alkenylphenols with protected phenolic hydroxyl groups or the said alkenylphenols and vinylaromatic compounds, with (meth)acrylic esters results in eliminating and/or decomposing the groups protecting the phenolic hydroxyl groups with acids selectively and partially. It was confirmed that alkenylphenol copolymers with narrow molecular distributions and controlled structures could be synthesized from the said block copolymers. Thus the present invention has been completed.
The present invention relates to alkenylphenol copolymers that Component (A) containing a repeating unit represented by Formula (I)
(wherein, R1 is hydrogen or methyl, R2 is alkyl having 1 to 5 carbons, m is 0, 1 or 2 and R2 is the same or different when m is 2) and a repeating unit represented by Formula (II)
(wherein, R3 is hydrogen or methyl, R4 is a group to be eliminated and/or decomposed with an acid, R5 is alkyl having 1 to 5 carbons, n is 0, 1 or 2 and R5 is the same or different when n is 2), and Component (B) containing a repeating unit represented by Formula (III)
(wherein, R6 is hydrogen or methyl, and R7 is a group having a t-butyl group and to be eliminated and/or decomposed with an acid) are bound in block in the (A)-(B) form, and that have a ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) in a range of 1.00 and 1.50 and without carboxylic acid residues. It also relates to the said alkenylphenol copolymers with weight-average molecular weight of 1,000 to 100,000.
The present invention relates to a process for the preparation of the said alkenylphenol copolymer, characterized by that a compound represented by Formula (IV) with the protected hydroxyl group of the phenol residue
(wherein, R8 is hydrogen or methyl, R9 is a group to be eliminated and/or decomposed with an acid, R10 is alkyl having 1 to 5 carbons, p is 0, 1 or 2 and R10 may be the same or different when p is 2) is polymerized, or a compound of Formula (IV) and a vinylaromatic compound are copolymerized, by anionic polymerization using an anionic polymerization initiator as a polymerization initiator, followed by copolymerization with a (meth)acrylic ester represented by Formula (V)
(wherein, R11 is hydrogen or methyl, and R12 is a group having a t-butyl group and to be eliminated and/or decomposed with an acid); and the obtained block copolymer is treated with an acid reagent to eliminate and/or decompose only a specified amount of the group protecting the phenolic hydroxyl group. The present invention also relates to a process for the preparation of the said alkenylphenol copolymer, characterized by that only a specified amount of the group protecting the phenolic hydroxyl group is eliminated and/or decomposed with an acid reagent at a temperature below 60xc2x0 C.
In the xe2x80x9crepeating unit of Formula (I)xe2x80x9d of the present invention, R1 is hydrogen or methyl. R2 is alkyl having 1 to 5 carbons. Examples of the alkyl group having 1 to 5 carbons include methyl, ethyl, n-propyl, isopropyl, n-butyl and t-butyl. m is 0, 1 or 2. When m is 2, R5 is the same or different. Positions of hydroxyl (OH) group and R2 are not specifically restricted. The hydroxyl group is preferably at the para or meta position of the alkenyl group.
In the xe2x80x9crepeating unit of Formula (II)xe2x80x9d of the present invention, R3 is hydrogen or methyl. R4 is a group to be eliminated and/or decomposed with an acid. Examples of the group to be eliminated and/or decomposed with an acid include functional groups such as those represented by the following formulae.
R5 is alkyl having 1 to 5 carbons. Examples of the alkyl group having 1 to 5 carbons include methyl, ethyl, n-propyl, isopropyl, n-butyl and t-butyl, n is 0, 1 or 2. When n is 2, R5 is the same or different. Substitution positions of the alkoxy (OR4) group and R5 are not specifically restricted. The alkoxy (OR4) group is preferably at the para or meta position of the alkenyl group.
In the xe2x80x9crepeating unit of Formula (III)xe2x80x9d of the present invention, R6 is hydrogen or methyl. R7 is a group having a t-butyl group and to be eliminated and/or decomposed with an acid. Examples of the groups having a t-butyl group and to be eliminated and/or decomposed with an acid include functional groups such as those represented by the following formulae (wherein, u is 0 or 1).
The polymers of the present invention may contain repeating units other than those represented by Formulae (I) to (III), if required. There are no particular restrictions on the repeating units if the units are produced from compounds having double bonds copolymerable with monomers corresponding to Formulae (I) to (III). Preferred are repeating units with no acidic substituents such as sulfonic acid group, carboxyl group and phenolic hydroxyl group. Examples of monomers corresponding to the said repeating units include compounds containing vinyl groups and compounds containing (meth)acryloyl groups.
Examples of the said compounds containing vinyl groups include aromatic vinyl compounds such as styrene, xcex1-methylstyrene, chlorostyrene, 1,1-diphenylethylene and stilbene; aromatic vinyl compounds containing hetero atoms such as vinylpyridine; vinyl ketone compounds such as methyl vinyl ketone and ethyl vinyl ketone; vinyl ether compounds such as methyl vinyl ether and ethyl vinyl ether; and alicyclic vinyl compounds containing hetero atoms such as vinyl pyrolidone and vinyl lactam.
Examples of the said compounds containing (meth)acryloyl groups include (meth)acrylic esters represented by Formula (IX) (wherein, R28 is hydrogen or methyl, R29 is alkyl having 1 to 12 carbons, hydrocarbon group having an alicyclic structure of 3 or more carbons, hydrocarbon group that has an alicyclic structure containing hetero atoms and having 2 or more carbons, or heteroaryl), or (meth)acrylonitrile.
Examples of R29 of Formula (IX) include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-octyl, n-decyl or functional groups represented by the following formulae (wherein, k is 0 or 1).
These compounds containing vinyl groups or containing (meth)acryloyl groups can be used alone or as a mixture of two or more. Repeating units obtained from these compounds containing vinyl groups or containing (meth)acryloyl groups can be contained in the alkenylphenol copolymers of the present invention by random or block copolymerization with repeating units of Formulae (I) to (III). An example of Component (A) containing a repeating unit represented by Formula (I) and that of Formula (II) includes Component (A) containing additional repeating units corresponding to styrene, xcex1-methylstyrene and the like as monomers. In this case, in Component A, a mole ratio of the repeating unit of Formula (I) to the total of the repeating unit of Formula (II) and the repeating unit corresponding to styrene or the like as a monomer is preferably in the range of 99/1 to 50/50.
The alkenylphenol copolymers of the present invention are characterized by block copolymerization of Component (A) containing the repeating units of alkenylphenol represented by Formulae (I) and (II) with Component (B) containing the repeating unit of (meth)acrylic ester represented by Formula (III), in the form of (A) (B). Actual examples of the alkenylphenol copolymers of the present invention follow:
Poly[p-t-butoxystyrene/p-hydroxystyrene/t-butyl (meth)acrylate],
Poly[p-t-butoxy-xcex1-methylstyrene/p-hydroxystyrene/t-butyl (meth)acrylatel],
Poly[p-t-butoxystyrene/p-hydroxy-xcex1-methylstyrene/t-butyl (meth)acrylate],
Poly[m-t-butoxystyrene/m-hydroxystyrene/t-butyl (meth)acrylate],
Poly[p-t-butoxystyrene/p-hydroxystyrene/t-butyl methacrylate/t-butyl acrylate],
Poly[p-t-butoxystyrene/p-hydroxystyrene/t-butyl (meth)acrylate/isobonyl (meth)acrylate],
Poly[p-t-butoxystyrene/p-hydroxystyrene/dicyclopentenyl (meth)acrylate/t-butyl (meth)acrylate],
Poly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/t-butyl (meth)acrylate],
Poly[p-t-butoxystyrene/p-hydroxystyrene/t-butoxycarbonylmethyl (meth)acrylate],
Poly[p-(tetrahydropyranyloxy)styrene/p-hydroxystyrene/t-butyl (meth)acrylate],
Poly[p-t-butoxystyrene/p-(tetrahydropyranyloxy)styrene/p-hydroxystyrene/t-butyl (meth)acrylate], and
Poly[(p-t-butoxystyrene/styrene/p-hydroxystyrene/t-butyl (meth)acrylate]
A ratio (Mw/Mn) of weight-average molecular weight (Mw) to number-average molecular weight (Mn), which represents the dispersibility of the alkenylphenol copolymers of the present invention, is in the range of 1.00 to 1.50, preferably 1.00 to 1.20. The weight-average molecular weight (Mw) is preferably in the range of 1,000 to 100,000, and more preferably 1,000 to 30,000. A mole ratio [(A)/(B)] of Component (A) to Component (B) is preferably in the range of 95/5 to 5/95, more preferably 95/5 to 70/30. There are no particular restrictions on mole ratios of the repeating unit of Formula (I) to that of Formula (II), which compose Component (A). It is preferable in the range of 99.5/0.5 to 50/50, and more preferably 95/5 to 60/40.
Of the compound of Formula (IV) used for the preparation of the alkenylphenol copolymers of the present invention, R8 is hydrogen or methyl, R9 is a group to be eliminated and/or decomposed with an acid, R10 is alkyl having. 1 to 5 carbons, and p is 0, 1 or 2. R10 is the same or different when p is 2. R9 corresponds to R4 in Formula (II), and R10 to R5 in Formula (II). Their actual examples are aforementioned.
Examples of the compounds of Formula (IV) include p-t-butoxystyrene, p-t-butoxy-xcex1-methylstyrene, m-t-butoxystyrene, m-t-butoxy-xcex1-methylstyrene, p-(tetrahydropyranyloxy)styrene, p-(tetrahydropyranyloxy)-xcex1-methylstyrene, p-(l-ethoxyethoxy)styrene and p-(1-ethoxyethoxy)-xcex1-methylstyrene. These can be used alone or as a mixture of two or more.
Examples of vinylaromatic compounds used for the preparation of the alkenylphenol copolymers of the present invention include styrene, o-methylstyrene, p-methylstyrene, p-t-butylstyrene, xcex1-methylstyrene, 1,3-butylstyrene, 1,1-diphenylethylene and stilbene. These can be used alone or as a mixture of two or more.
Of the (meth)acrylic esters of Formula (V) used for the preparation of the alkenylphenol copolymers of the present invention, R11 is hydrogen or methyl, R12 is a group having a t-butyl group and to be eliminated and/or decomposed with an acid. R12 corresponds to R7 in Formula (III). Its actual examples are aforementioned.
Examples of the compounds of Formula (V) include t-butyl (meth)acrylate, t-butoxycarbonylmethyl (meth)acrylate and 1-methyl-t-butoxycarbonylmethyl (meth)acrylate. These can be used alone or as a mixture of two or more.
To produce an alkenylphenol copolymer of the present invention, first anionic polymerization of a compound of Formula (IV) alone, or a compound of Formula (IV) and a vinylaromatic compound, is carried out with an anionic polymerization initiator used as a polymerization initiator, followed by a block copolymerization reaction by adding a (meth)acrylic ester of Formula (V) to the reaction system. The reaction is usually carried out under the atmosphere of inert gas, such as nitrogen or argon, in an organic solvent at xe2x88x92100 to 50xc2x0 C., preferably xe2x88x92100 to 0xc2x0 C., more preferably xe2x88x92100 to xe2x88x9220xc2x0 C.
Examples of anionic polymerization initiators used for the said anionic polymerization include alkali metals and organic alkali metals. Examples of the alkali metals include lithium, sodium, potassium and cesium. Examples of the organic alkali metals include alkyl, alkyl and aryl compounds of the above alkali metals. These anionic polymerization initiators can be used alone or as a mixture of two or more. Examples of the organic alkali metals include ethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, ethyl sodium, lithium biphenyl, lithium naphthalene, lithium triphenyl, sodium naphthalene, xcex1-methylstyrene sodium dianion, 1,1-diphenylhexyl lithium and 1,1-diphenyl-3-methylpentyl lithium.
Examples of organic solvents used for the said polymerization reactions include aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and cyclopentane; aromatic hydrocarbons such as benzene and toluene; and ethers such as diethyl ether, tetrahydrofuran and dioxane, as well as those usually used for anionic polymerization such as anisole and hexamethylphosphoramide. These are used alone or as a mixed solvent of two or more. A combination of polar solvents and non-polar solvents is particularly preferred. It is more favorable to combine ethers with aromatic or aliphatic hydrocarbons.
When copolymerization is carried out with a (meth)acrylic ester added, an addition of an alkali metal salt and/or alkaline earth metal salt of a mineral acid can control the polymerization reaction. Lithium chloride is particularly preferred to use as the alkali metal salt and/or alkaline earth metal salt of a mineral acid.
From a copolymer thus obtained, a certain amount of the group protecting the phenolic hydroxyl group is eliminated and/or decomposed with an acid reagent, to form the alkenylphenol structure. Examples of solvents used for the elimination/decomposition reaction include alcohols such as methanol and ethanol; ketones such as acetone and methyl ethyl ketone; polyhydric alcohol derivatives such as methyl cellosolve and ethyl cellosolve; and water, in addition to those exemplified for the above polymerization reactions. These may be used alone or as a mixture of two or more.
There are no particular restrictions on acid reagents used. Actual examples of the acid reagents include hydrochloric acid, sulfuric acid, hydrogen chloride gas, phosphoric acid, hydrobromic acid, p-toluenesulfonic acid, 1,1,1-trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid and hydrogen sulfates represented by Formula XHSO4 (wherein, X is an alkali metal such as Li, Na or K). A catalytic amount is sufficient to use. Usually, the mole fraction of each unit and the average molecular weight of the whole polymer from the molecular weight of each unit are calculated. The mole number of each unit is calculated from the total weight, average molecular weight and mole fraction of the polymer. An amount of acid reagent used is in the range of 0.1 to 3 equivalents, preferably 0.1 to 1 equivalent, to the mole number of the alkenylphenol unit.
The elimination reaction of the protecting group is usually carried out at room temperature to 150xc2x0 C. It is however carried out in the range of room temperature and below 70xc2x0 C., preferably room temperature and below 60xc2x0 C., and more preferably 30xc2x0 C. and 50xc2x0 C., in order to control the hydrolysis of the (meth)acrylic ester portion when the phenolic hydroxyl group is deprotected. The hydrolysis of the ester portion can be controlled even if the reaction is carried out at above 60xc2x0 C., if the (meth)acrylic ester has a bulky substituent such as alicyclic group having 7 or more carbons or alkyl having an alicyclic group.
In the deprotection reaction, appropriate combinations between a type and concentration of a solvent, type and addition amount of a catalyst, and a reaction temperature and reaction time can control the hydrolysis of the (meth)acrylic ester and deprotection of the phenolic hydroxyl group. For example, the elimination reaction rate can be controlled in a way that a reaction is carried out keeping a temperature at 60xc2x0 C. at the initial stage of the reaction to remove 80 to 90% of the specified amount, and the reaction temperature is then lowered and, if necessary, water is added to adjust the acid concentration. As a result, a target product can be obtained at the accuracy of about xc2x11% to the specified amount.
To eliminate only a desired, specified amount of the protecting group, the reaction is tracked as required, and the reaction is stopped when the specified amount is eliminated. Examples of means to track the reaction include IR spectra or methods of measuring changes in polymer solubility.

Alkenylphenol copolymer and process for producing the same


A wing or stabilizer of an aircraft. The wing or stabilizer comprises a box portion, comprising at least one spar and an outer skin coupled to the at least one spar. The wing or stabilizer also comprises at least one panel, comprising an outer face-sheet and an inner face-sheet. In a fore-aft direction the outer face-sheet terminates at an outer free edge. In the fore-aft direction the inner face-sheet terminates at an inner free edge. The at least one panel also includes a core sandwiched between the outer face-sheet and the inner face-sheet. The inner face-sheet comprises a cantilevered portion. The cantilevered portion defines the inner free edge. The cantilevered portion is fastened to the outer skin of the box portion.

Some stabilizers and wings of conventional aircraft include a panel (e.g., an edge panel) coupled to the skin of a stabilizer box or wing box. For skins made of metal, some aircraft machined recesses in the skins to receive the panel. However, for skins made of a non-metal, such as a fiber-reinforced polymer material, machining recesses into the skins is impractical due to the potential degradation of the fibers.
One known solution for coupling skins and panels made of fiber-reinforced polymer materials is to indirectly couple the skin of the stabilizer box and the panel with an adapter piece that extended between the panel and the skin (e.g., box skin). Fasteners secured the adapter piece to the panel and separate fasteners secured the adapter piece to the skin. The adapter piece and additional fasteners required to implement this solution added weight and cost to the aircraft.
Another solution aimed to eliminate the adapter piece and reduce the number of fasteners for coupling together skins and panels made of fiber-reinforced polymer materials included the placement of a toughened, low density filler in a gap between the skin and a shallow-angled portion of the panel. The toughened, low density filler is difficult to work with, has a low durability, and is susceptible to damage.


A vacuum attachment for use with a vacuum hose, which is for use with a vacuum device, and a container, particularly any conventional plastic food storage bag. The vacuum attachment has a first attacher for attaching the vacuum attachment to the vacuum hose, and an inserter for inserting the vacuum attachment into the container. The first attacher may be a hollow substantially frustoconical body. The inserter may be a hollow substantially cylindrical neck. The vacuum attachment may also have a second attacher, such as a suction cup, for attaching the vacuum attachment to a planar surface. The vacuum attachment may also have an air flow blocker for blocking the air flow between the container and the vacuum attachment. The air flow blocker may be a hollow substantially cylindrical cap with a closed end. The air flow blocker may have an opening or a filter.

1. Field of the Invention
The present invention relates to a vacuum attachment adapted for use with a vacuum hose, which is adapted for use with any type of vacuum device, and any type of container, particularly any conventional plastic food storage bag.
2. Description of the Related Art
Many devices have been proposed for the purpose of removing air from a container in order to store and preserve food or in order to reduce the volume of an item, such as clothing, inside a container to facilitate storage. However, these devices are typically expensive and often require the purchase of customized storage bags. Many of the devices include an expensive vacuum unit and cannot be used with a household vacuum that a typical consumer already owns.
Some of the devices include an electrical sealing or heating unit. Some devices with sealing or heating units bear a warning label stating that use of the sealing or heating device with a plastic bag xe2x80x9ccould cause fumes,xe2x80x9d which are potentially harmful. Also, these sealing or heating units are known to burn out, rendering the device ineffective.
A variety of devices have been proposed for use with a vacuum device. U.S. Pat. No. 4,018,253, issued Apr. 19, 1977 to Kaufman, describes a home vacuum apparatus for freezer bags. U.S. Pat. No. 4,750,536, issued Jun. 14, 1988 to Grisley, describes a router vacuum attachment. U.S. Pat. No. 6,093,168, issued Jul. 25, 2000 to Mendenhall, describes a breast pump attachment to a household vacuum cleaner.
Further, German Patent No. 19959513 C1, issued Jul. 26, 2001 to Bruno, describes an electric vacuum cleaner attachment with an adapter piece fitted to a suction hose and a filter device extending in a longitudinal direction of the suction hose. U.S. Patent Application Publication No. 2002/0092103 A1, published Jul. 18, 2002 to Bruno et al., describes a universal vacuum extension kit. Also, U.S. Pat. No. 5,711,501, issued Jan. 27, 1998 to Belokin et al., describes a suction cup attachment assembly.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a vacuum attachment solving the aforementioned problems is desired.
The vacuum attachment of the present invention is adapted for use with a vacuum hose which is adapted for use with any type of vacuum device and any type of container, particularly any conventional plastic food storage bag. The vacuum attachment comprises a first attaching means adapted for attaching the vacuum attachment to the vacuum hose, and an inserting means adapted for inserting the vacuum attachment into the container. The first attaching means and the inserting means are preferably integrated into a one-piece construction; however, the first attaching means and the inserting means may be provided as separate pieces which are attached together using any suitable means of attachment.
The first attaching means may comprise a hollow substantially frustoconical body. The inserting means may comprise a hollow substantially cylindrical neck. The vacuum attachment may further comprise a second attaching means, such as a suction cup, adapted for attaching the vacuum attachment to a planar surface. The vacuum attachment may further comprise an air flow blocking means adapted for blocking the air flow between the container and the vacuum attachment. The air flow blocking means may comprise a hollow substantially cylindrical cap with a closed end. The air flow blocking means may comprise an opening or a filter.
Accordingly, it is a principal object of the invention to provide a vacuum attachment for use with a vacuum hose and a container.
It is another object of the invention to provide a vacuum attachment comprising a first attaching means and an inserting means.
It is a further object of the invention to provide a vacuum attachment comprising a hollow substantially frustoconical body.
Still another object of the invention is to provide a vacuum attachment comprising a hollow substantially cylindrical neck.
It is another object of the invention to provide a vacuum attachment comprising a second attaching means.
It is a further object of the invention to provide a vacuum attachment comprising a hollow substantially cylindrical cap.
Still another object of the invention is to provide a vacuum attachment comprising an air flow blocking means comprising an opening or a filter.
It is another object of the invention to provide a vacuum attachment which is adapted for use with a conventional vacuum device.
It is a further object of the invention to provide a vacuum attachment which is adapted for use with a conventional plastic food storage bag.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.


A display memory circuit includes a drawing memory and a dynamic display memory. The drawing memory stores data and at least a portion of the data are possibly rewritten into a new data at a third timing, the third timing being optional between a first timing and a second timing. The dynamic display memory is connected with the drawing memory, which latches the data in response to the first timing and continues to hold the data between the first timing and the second timing. The drawing memory is partially disconnected from the dynamic display memory in the rewritten portion when the portion is rewritten in the drawing memory.

1. Field of the Invention
The present invention relates to a display controller with a display memory circuit, and more particularly to a display controller with a display memory circuit in which a multi-port memory is used.
2. Description of the Related Art
A conventional display memory circuit is widely used for a display controller or a display system to control a display apparatus to display an image. For instance, in case of a matrix type display apparatus such as a liquid crystal display apparatus, the circuit of a display controller is integrated and installed adjacent to a display panel of the display apparatus. The display controller drives H data lines arranged in parallel to a vertical direction of the display panel directly.
FIG. 1 is a block diagram showing a conventional display controller and a peripheral circuit of the display controller. The display controller 106 includes a display memory 161, a latch circuit 162, a data line driving circuit 163, a memory control circuit 164 and a timing control circuit 165. Here, a drawing unit 107 carries out a drawing process, and a gradation voltage generating circuit 108 generates gradation voltages V0 to V9. Also, a gate line driving circuit 109 selects and drives V gate lines arranged in parallel to the horizontal direction of the display panel in accordance with scanning of the display frame. A display section has the size of H pixels×V pixels×8 bits.
The display memory 161 is a 2-port memory with an external port and a read port only for a reading operation and is configured as a display memory circuit in the display controller. The display memory 161 is accessed by the drawing unit 107 through the external port. The display memory 161 receives and stored therein RGB display data of H pixels×V pixels×8 bits for one frame transferred from the drawing unit 107. Then, the display memory 161 sequentially select read word lines or horizontal lines in response to the scanning of the display frame and outputs the RGB display data in units of H pixels×8 bits from the read port to the latch circuit 162.
FIG. 2 is a circuit diagram showing the simplest example of the memory cell of this conventional multi-port memory shown in Japanese Laid Open Patent Application (JP-A-Heisei 8-161890). A memory cell of the multi-port memory is connected with a write bit line and a read bit line, and is selected by a write word line and a read word line. The memory cell is asynchronously accessed through the read port and a write port as the external port.
The latch circuit 162 latches the RGB display data of H pixels×8 bits, which have been read out from the read port of the display memory 161, in synchronism with a display clock, and then outputs the latched data to the data line driving circuit 63.
The gradation voltage generating circuit 8 generates 64 gradation voltages expressed by gradation voltages V0 to V9. The data line driving circuit 163 converts the RGB display data into analog signals by selecting one of 64 gradation voltages for one pixel based on the RGB display data of H pixels×8 bits outputted from the latch circuit 162. Then, the data line driving circuit 163 drives the H data lines in the display section in parallel. The V lines are sequentially driven by the gate line driving circuit 109.
The memory control circuit 164 inputs the memory control signal including an address signal from the drawing unit 107 to control the writing operation into the display memory 61 by the drawing unit 107. Also, the memory control circuit 164 inputs a synchronization signal and a display clock signal of the display frame from the timing control circuit 165 to control the reading operation from the display memory 161.
The timing control circuit 165 inputs the timing control signal from the drawing unit 107 and generates the synchronization signal and the display clock signal of the display frame to output the latch circuit 162, the memory control circuit 164 and the gate line driving circuit. 109. Thus, the timing control circuit 165 carries out a timing control of the scanning of the display frame.
This conventional display controller 106 stops the transfer of image data from an external unit, and drives the display section based on the RGB display data already stored in the display memory 161, when the display image is not dynamically changed like a still image. On contrary, when the display image is a video image, only the RGB display data of a changed portion of the display image is transferred. Thus, a reduction in power consumption is achieved.
Next, FIG. 3 is a block diagram showing another example of a conventional display system shown in Japanese Laid Open Patent Application (JP-P2000-250733A). The conventional display system includes a drawing memory 181, a display memory 182, a transfer control section 183, a timing control section 184, a display control circuit 185, and a CPU 186. Here, the functions of the display memory 182 and the display control circuit 185 correspond to the function of the display controller 106 shown in FIG. 1. The drawing memory 181 and the display memory 182 are used as a display memory circuit in the display system.
The drawing memory 181 is a work memory for the CPU 186 to store an image data. The display memory 182 stores an image data for the CPU 186 as a display data, like the display memory 161 shown in FIG. 1.
The transfer control section 183 starts the control of the transfer of the image data from the drawing memory 181 to the display memory 182 in response to a transfer start signal b and outputs a transfer end signal to the timing control section 184. The timing control section 184 outputs the transfer start signal b to the transfer control section 183 in response to a transfer start signal a from the CPU 186 and a non-display period start signal after the transfer start signal is made valid. Then, the timing control section 184 outputs a transfer execution signal to the CPU 16 until the transfer end signal is inputted.
The display control circuit 185 reads out the RGB display data from the display memory 182 in a constant period to transfer the data to the display section, and outputs the non-display period start signal to the timing control section 184. The CPU 186 carries out the drawing processing. After writing operation into the drawing memory 181, the CPU 186 outputs the transfer start signal a to the timing control section 184.
In this display system, the display control circuit 185 reads out the display data from the display memory 182 in a constant period, and carries out D/A conversion to the read out display data to transfer the data to the display section. The period that the display data for one frame is transferred to the display section is a display period. The non-display period is usually very shorter than the display period. When the CPU 186 changes the display data, the CPU 186 writes a new drawing data in the drawing memory 181. In this initial state, the CPU 186 and the display control circuit 185 can asynchronously access the drawing memory 181 and the display memory 182, respectively, because the transfer control section 183 is not operating. After the writing operation of the drawing data into the drawing memory 181, the CPU 186 outputs the transfer start signal a to the timing control section 184. After confirming invalidation of the transfer execution signal, the CPU 186 writes the next drawing data in the drawing memory 181 to update the stored data to the next drawing data.
Next, when the CPU 186 outputs the transfer start signal a to the timing control section 184, the timing control section 184 outputs the transfer execution signal to the CPU 186, and the transfer start signal b to the transfer control section 183 in response to the non-display period start signal. The transfer control section 183 transfers the drawing data from the drawing memory 181 to the display memory 182 in response to the transfer start signal b. This period is the non-display period in which the drawing memory 181 and the display memory 182 are not accessed by the CPU 186 and the display control circuit 185. As a result, it is possible to carry out the above transfer normally. When the transfer is completed, the transfer end signal is outputted from the transfer control section 183 to the timing control section, and the transfer execution signal is made invalid by the timing control section 184. In the next display period, the updated display data of the display memory 182 is read out by the display control circuit 185 and is outputted to the display section. Therefore, the display data on the updating operation is never displayed, and the updated display data in units of frames is displayed. Thus, the display screen never fall into disorder.
In this way, in recent years, in the display controller of a portable equipment, high precision display and a multi-function such as a video image reproduction are progressing based on user demand. It is possible to accomplish the high precision display by increasing the capacity of a display memory. Also, it is possible to accomplish the multi-function by adding a drawing circuit or a CPU and the drawing memory to the display controller and by transferring the data from the drawing memory to the display memory during the non-display period, like the display system shown with FIG. 3.
However, in this case, the display memory needs a memory capacity to store the RGB display data for at least one frame in order to reduce consumption power during the data transfer. Also, the drawing memory also needs a memory capacity to store the drawing data for one frame. Therefore, the memory capacity of the display memory circuit becomes large, resulting in increase of the circuit scale of the display controller.
Also, a data transfer quantity from the drawing memory to the display memory increases and the consumption power increases. Especially, since the data are transferred in units of frames between the display controller and the drawing apparatus, the data transfer quantity increases, resulting in increase of the consumption power. As a result, the battery duration of the portable equipment becomes short.
Also, in the display system shown in FIG. 3 and containing the drawing memory and the display memory, the similar problems such as the increase of the circuit scale and the increase of consumption power are caused.

Display controller with display memory circuit


A fluid device (pump or motor) comprises a case having a closed chamber, a rotating element mounted for rotation within the closed chamber, a reciprocating piston drivingly connected to the rotating element such that rotation of the rotating element corresponds to reciprocating movement of the piston, passages for admitting and discharging fluid to and from a cylinder in which the piston reciprocates, and scavenger pump means drivingly connected to the rotating element and operable to pump fluid out of the closed chamber at a rate greater than the rate at which fluid leaks or otherwise is metered into the interior chamber, thereby to maintain the level of fluid within the closed chamber below a predetermined level.

Rotating fluid pumps and motors, and especially rotating piston pumps and motors, are well known in the prior art. The pumps are often used in hydraulic systems to provide fluid power to components such as hydraulic cylinders and rotary actuators. The fluid motors are often used to provide mechanical power to components such as electrical generators.
Rotary piston pumps and motors are characterized by a rotating piston group and associated swash plate. In a typical arrangement, a plurality of pistons are carried in a barrel that is rotatably mounted in a case. The pistons project from an axial end of the barrel for engagement with the swash plate. In a pump, the barrel is rotatably driven as by means of an input shaft coupled thereto. When the barrel rotates, the pistons are reciprocated back and forth within respective cylinders in the barrel through interaction with the swash plate that is tilted to the axis of the barrel. The piston cylinders are sequentially connected to inlet and outlet passages such that the reciprocating movement of the pistons draws fluid into the cylinder from an inlet passage and pushes the fluid out through an outlet passage.
A rotary piston motor operates generally in reverse manner. The cylinders in the barrel are sequentially connected to a hydraulic fluid supply and return. When the pistons are axially driven by fluid pressure against the tilted swash plate, a reactionary torque is applied to the barrel thereby to rotate the barrel and in turn an output shaft.
In such pumps and motors, windage losses arise when the pump/motor case is filled with hydraulic fluid. Hydraulic fluid may leak from the rotating piston group thereby pressurizing the case and causing fluid flow out of a case drain port and back to the reservoir of the hydraulic system. It is desirable to scavenge the pump/motor case to reduce windage losses and thereby increase efficiency of the pump or motor. Although the benefits of scavenging the case have long been known, this has not been successfully implemented in a closed hydraulic system where the case is not directly vented to atmosphere. Accordingly, there exists a need for a pump and/or motor that obtains the benefits of a scavenged case in a closed hydraulic system where the case is not directly vented to atmosphere. Moreover, the solution should be such that air is not ingested into the hydraulic system due to a dynamic seal or seals being subjected to low scavenge pressure in the case.


A misalignment compensating optical sensor (222), that is operable to receive excitation light (30) having a range of input propagation angles ω. The sensor (222) has a variable reflected propagation angle θ0i reflective surface (227) and a sensing waveguide (228). The shape of the reflective surface (227) is selected to maximize the amount of the excitation light (30) it reflects into the sensing waveguide (227) despite misalignment errors between the sensor (222) and the source (58) of excitation light (30). The sensor may also have a lens portion (160) for focusing the excitation light (30) onto the reflective surface (227), and/or a lens portion (174) for collimating the output of signal recovery light (32) from the waveguide (228). An iterative method may be used for designing any particular lens portion (160, 174).

There exists a need for a highly sensitive and specific technology directed to the detection of human pathogens and toxins in food, water, and the environment. It is very difficult to effectively detect organisms in natural fluids such as milk, blood, sewage, and meat products at low concentration and to discriminate between pathogenic and harmless species. Conventional bioassay methods are commonly designed for samples on the order of a few cubic centimeters, and the extraction or concentration of pathogenic material from larger volumes to met sensitivity requirements creates additional challenges.
One of the most promising strategies for performing pathogen assays on raw, unpurified samples is based on sensors that harness biological ligand-receptor interactions to identify specific compounds. Examples of approaches that implement such a strategy include fiber optic evanescent wave sensors and surface plasmon resonance sensors.
An electromagnetic wave, traveling through one material, that is reflected at a dielectric interface produces an exponentially decaying electric field within the second material on the opposite side of the interface. At optical frequencies this is termed the evanescent wave effect, and at radio frequencies this phenomenon is often called a "skin effect." The penetration depth within the second material, the evanescent wave region, is a small fraction of a wavelength, yet greater in size than most optical labels such as light- or fluorescence-producing reporter molecules, light-absorbing or scattering molecules, and colloidal particles and microspheres. These labels can be used to monitor or produce optical changes in the evanescent region, or modify the propagation of light in the adjacent dielectric, providing a fundamental means of detecting target materials that are close to the surface while discriminating against those far away. In particular, by coating the interface with a capture agent that is specific for a microscopic or molecular target of interest, exquisitely sensitive optical-based sensors can be created.
In one competitive assay technique, fluorophore-labeled antigen 104, together with the sample to be tested, is exposed to the coating of capture antibody 100 on the fiber, and the labeled antigen competes for antibody binding sites with non-tagged analyte 106 in the test sample. The evanescent field produced by light 108 passing through the fiber 102 then excites the fluorophores into light emission 110, and the fiber itself conveniently acts as a return waveguide for the fluorescent signal. In this example, the strength of the fluorescent signal is inversely related to the analyte concentration in the test sample. Alternatively, a non-competitive technique, such as a sandwich-format assay, can be used, in which case the fluorescent signal is directly related to the analyte concentration in the test sample. High sensitivity and specificity can be achieved for a wide range of metals, toxins, proteins, viruses, living and dead bacteria, and spores, through the use of bound target-specific agents 100 such as chelating agents, antibodies, crown ethers and the like, combined with appropriate optical labels that luminesce, fluoresce or alter light transport by the waveguide. In applications where pathogens will be infrequently found, cost per assay may be low since the sensor remains active until the capture agents have been substantially neutralized by the binding of the target material.
For surface plasmon resonance sensing, FIG. 1B shows a thin layer of metal 110, such as gold, applied to a core portion 112 of an optical fiber 114 from which the cladding 116 of the fiber has been partly removed. The evanescent electric field produced by light 118 passing through the fiber 114 excites surface plasmon waves 120 on the outer surface of the metal 110. When white light is passed through the fiber 114, the excitation of a surface plasmon wave causes a dip in the spectrum of the light passing through the fiber, with the dip occurring at a resonance wavelength which is a function of the complex indices of refraction of the fiber core, the metal layer, and the fluid surrounding the fiber, as well as the incidence angle of the light. Light passing through the fiber 114 can be returned by a mirror 122, or can be passed through the distal end of the fiber (in the absence of a mirror) for optical processing and analysis, as is well known to those skilled in the art. Any change in the index of refraction of the fluid is detectable, and molecules binding to the surface of the metal 110 can then be detected if they have an index of refraction that is different from the bulk fluid. Coating the metal layer 110 with target-specific capture molecules (not shown), which react with target analytes within a sample fluid, then allows detection of reactions (such as antigen-antibody reactions and reduction-oxidation reactions) on the surface of the metal.
Fiber optic evanescent wave sensors are the subject of a number of U.S. patents, including the following, the disclosures of each being incorporated herein by reference: U.S. Pat. No. 4,447,546, to Hirschfeld et al., entitled "Fluorescent Immunoassay Employing Optical Fiber in Capillary Tube"; U.S. Pat. No. 4,558,014, to Hirschfeld et al., entitled "Assay Apparatus and Method"; U.S. Pat. No. 4,582,809, to Block et al., entitled "Apparatus Including Optical Fiber for Fluorescence Immunoassay"; U.S. Pat. No. 4,654,532, to Hirschfeld, entitled "Apparatus for Improving the Numerical Aperture at the Input of a Fiber Optic Devices"; U.S. Pat. No. 4,716,121, to Block et al., entitled "Fluorescent Assays, Including Immunoassays, with Feature of Flowing Sample"; U.S. Pat. No. 4,909,990, to Block et al., entitled "Immunoassay Apparatus"; U.S. Pat. No. 5,242,797, to Hirschfeld, entitled "Nucleic Acid Assay Method"; U.S. Pat. No. 5,061,857, to Thompson et al., entitled "Waveguide-Binding Sensor for Use With Assays"; U.S. Pat. No. 5,430,813, Anderson et al., entitled "Mode-Matched, Combination Taper Fiber Optic Probe"; U.S. Pat. No. 5,152,962, to Lackie, entitled "Immunoassay Apparatus"; U.S. Pat. No. 5,290,398, to Feldman et al., entitled "Synthesis of Tapers for Fiber Optic Sensors"; and U.S. Pat. No. 5,399,866, to Feldman et al., entitled "Optical System for Detection of Signal in Fluorescent Immunoassay." Fiber optic surface plasmon resonance sensors are the subject of U.S. Pat. No. 5,359,681 to Jorgenson et al., entitled "Fiber Optic Sensor and Methods and Apparatus Relating Thereto," the disclosure of which is incorporated herein by reference.
For evanescent wave sensors, it is desirable to optimize the magnitude of the evanescent electric field as well as to optimize the optical properties of the return path for the detected fluorescence. The above-identified patents describe numerous optimization approaches, including attempts to match the numerical aperture of various system components and to improve system numerical aperture. Numerical aperture is a measure of the largest angle, relative to the optical axis of a system, that a ray of light can have and still pass through the system. Each component in an optical system will have its own unique limiting numerical aperture, and the maximum system numerical aperture will be determined by the system component having the lowest numerical aperture. The system numerical aperture is a key parameter in optical sensing since transferred power is typically proportional to its square. Good design practice and cost efficiencies require system components to have matching numerical apertures.
One well-known approach of matching numerical apertures employs tapered or cone-shaped waveguides. In addition to providing numerical aperture matching, tapering the active, analyte-sensitive portion of the optical fiber maintains a substantial fraction of the input light near the critical angle, thereby maintaining a high magnitude evanescent field. However, there is also a constant loss of light along the sensor fiber as the taper acts upon rays that are already only weakly guided and causes them to exceed the critical angle.
In order for white light to propagate in an optical fiber used in connection with a surface plasmon resonance sensor, the fiber must have a large enough diameter to support the longest wavelength of light. Also, a large diameter fiber propagates higher numerical aperture light, which makes it easier to excite surface plasmon waves in metal films of a thickness readily fabricated by conventional processes. As a consequence, multi-mode fibers are used which propagate light over a range of angles. However, this range of angles results in a less distinct resonance effect, because each angle of propagation results in a different resonance wavelength.
FIG. 2A shows the theoretical resonance curves for various propagation angles relative to the optical axis of the fiber core, assuming a 55 nm thick layer of gold on a silica optical fiber core immersed in water. The overall resonance detected is a superposition of the resonance effects for each of the various angles of propagation. FIG. 2B shows the integration of individual theoretical resonance curves for propagation angles from 0 to 23.6 degrees, assuming a sine-squared distribution of optical power at the various propagation angles. The significant signal degradation associated with current approaches to surface plasmon resonance sensing is seen by comparing the resonance curve of FIG. 2B with the individual resonance curve of, for example, 23.6 degrees in FIG. 2A.
The first evanescent waveguide sensors, described in the early 1980's, were for substantially cylindrical waveguides, that is, waveguides with circular cross-sections in which light uniformly filled the entire cross-sectional area. Recent development has strongly emphasized slab waveguides excited by collimated light beams. A slab or planar waveguide may comprise a pair of parallel, internally reflecting surfaces sharing a common optical plane of symmetry.
In these devices, light is only contained in one dimension and lateral spreading is totally defined by excitation optics. This substantial shift has occurred primarily due to an interest in creating multianalyte assay arrays by printing a linear or two-dimensional pattern of capture agent spots on one surface of the slab waveguide within the illumination path of the light beam, and then monitoring for an optical signal from individual analyte-specific spots with a CCD detector array or photomultiplier on the other side of the slab waveguide.
However, the slab approach has some other weaknesses in addition to its limited light guiding ability. Due to the typically small size of individual assay spots it is a challenge to effectively contact each dot with the entire fluid sample. This is of particular significance when foodstuffs are tested for pathogens. Regulations may require, because of high health risks at extremely low pathogen levels, that assay samples of 300 cubic centimeters or more be utilized. By way of example, the acceptance limit set by the US Department of Agriculture for Escherichia coli O157:H7 is one organism per 25 gm of sample. It is very difficult to effectively detect organisms at such a low concentration with methods based on bioassay dots of typically 1 mm2 or less area. In addition, sample heterogeneity becomes an issue when raw food samples are examined. Fat globules and other non-toxic components may adhere non-specifically to the sensor or physically block contact with the target, reducing the effective sensitivity. Samples may also be viscous which increases the mass transfer boundary layer thickness and decreases the diffusive mass transport rates. These factors may yield low signal levels and create poor assay statistics where the target is a low, yet lethal concentration of a human or animal pathogen.
Analyte mass-diffusion boundary layers are also typically thicker for slab structures than for solids of revolution, such as cylinders. For related reasons a slab geometry may be more difficult to clean if the assay involves a multi-step protocol such as a sandwich immunoassay, or if it is desired to reuse the sensor. Finally, for applications such as food safety the number of target pathogens may be only one to six, calling into question the value of low sensitivity array techniques that require sophisticated and possibly costly CCD or photomultiplier signal recovery techniques.
Although evanescent wave and surface plasmon resonance sensors show great promise for use in medical and food safety applications, those skilled in the art understand that the current technology is less than optimal in a number of respects, including those disadvantages identified above.
There also exists a need for an improved optical sensor that helps to compensate for lateral, axial and/or angular misalignment errors of the sensor and its source of input excitation light with respect to each other. This is because such misalignment errors will normally cause undesirable degradations in the amount and/or the propagation angle(s) of the rays of the excitation light that are transported by an ordinary optical sensor's sensing waveguide. This, in turn, normally causes corresponding undesirable degradations in the amount of the signal recovery light that is returned by the sensing waveguide. In other words, such misalignment errors normally degrade the overall performance of an ordinary optical sensor. This need exists for both cylindrical and slab waveguide sensor designs.
Needs also exist for an improved optical sensor that includes lens(es) that help to enhance the amount of the excitation light that is delivered to the sensing waveguide, and/or that help to enhance the degree to which the signal recovery light from the sensing waveguide is collimated; and for methods for designing lenses that will satisfy one, or both, of these needs, to thereby enhance the overall performance of an ordinary optical sensor.

Misalignment compensating optical sensor and method


In an rf coil of a magnetic resonance apparatus steps are taken to optimize a uniform rf measuring field. To this end, axially extending current conductors are provided with means for generating a non-constant effective current intensity in current paths extending across a cylindrical surface so as to be parallel with a symmetry axis of the coil. This can be realized by deflecting axial conductors away from the cylindrical surface, by partly shielding them, by adding auxiliary coils to be individually controlled, or by connecting L-C circuits across the current conductors.

The invention relates to a magnetic resonance apparatus, comprising a magnet system for generating a steady magnetic field, a gradient magnet system, and an rf coil system which comprises an rf coil in which mutually parallel current paths extending axially across a cylindrical surface can be introduced, and also relates to a method of designing an rf coil for such an apparatus.
A magnetic resonance apparatuses of this kind is known from EP 213 665 which corresponds to U.S. Pat. No. 4,737,718. The apparatus described therein comprises a bird-cage rf coil which is composed of two ring conductors which are interconnected by way of a number of axial extending longitudinal wires which extend parallel to one another and parallel to a symmetry axis and which are situated on a cylinder defined by the ring conductors. When impedances and reactances are suitably chosen, a spatially uniform rf field can be generated in the coil by means of a cosine wave applied to the ring conductors.
U.S. Pat. No. 4,712,067 describes an rf coil which is composed of a number (for example two) of saddle-shaped coils whereby, using a suitable mutual coupling and correct control, a spatially uniform rf field can be generated in a mode which depends on the control and the mutual orientation of the current conductors. Current conductors which extend mutually parallel and parallel to a symmetry axis again form active longitudinal wires of the coil which are situated on a cylindrical surface.
EP 218 290 which corresponds to U.S. Pat. No. 4,839,595 describes an rf coil in the form of a so-called surface coil. Such a coil comprises a current conductor which is situated in one plane and through longitudinal wires of which there extends an imaginary cylinder, on a cylindrical surface of which the longitudinal wires extend in the axial direction so as to be mutually parallel and parallel to a symmetry axis. A plurality of such coils can be combined as described so as to form a butterfly coil.
In the types of coil described therein an rf field having a reasonably spatial homogeneity can be generated in a space which is enclosed by the current conductor or which is defined thereby and spin resonance signals can be detected from such space. The dimension of the rf measuring field space is determined by the geometry of the coil and will always be smaller than a space defined by the geometry of the coil. The filling factor which is to understood to mean herein, the part of the space in which the rf field is sufficiently uniform and which forms part of the geometrically defined space, can be increased in the radial direction by using a larger number of longitudinal conductors. Inter alia because a larger radius of a cylindrical coil makes the coil space more accessible, an acceptable solution can be found, at the expense of a higher energy consumption. In the axial direction the filling factor is reduced by increasing the diameter while maintaining the axial length of the coil; a smaller diameter makes the coil less accessible. When the length of the coil is increase, the rf measuring field space becomes larger but more energy will be consumed and the patient load will increased at areas where the load is not effectively used.
Homogeneity of rf coils for MR apparatus is important both for uniform excitation of spins and for uniform reception sensitivity for spin signals.
In addition, for transmitter coils it is important, from a point of view of rf power supply, and for receiver coils it is important from a point of view of signal-to-noise ratio that the rf coil has a sensitivity which is as compatible as possible with the space in which MR takes place. This implies a high filling factor. Known coils all exhibit a substantial dispersion field in the direction of the main axis. The ideal field profile of an rf coil is a block: sensitive only in the center and insensitive outside the center.
Because coils have a finite length in practice and are not bounded by an ideally conductive shield, the amplitude will always decrease towards the edge and the field will project outside the geometrical coil volume.
The transverse homogeneity is dependent on the number of current conductors situated on the circumference of the coil. In contemporary coils the current intensity in the conductors is cosinusoidal modulated as a function of the circumferential angle. The current intensity in a conductor, however, is constant. Thus, the homogeneity in non-central transverse planes is poor and the profile of the field along the main axis necessitates a long coil which, however, will have a poor filling factor. Homogeneity and field definition are in principle incompatible and are even contradictory in conventional coils.

Magnetic resonance apparatus with an optimized detection field


A spray tip including a spray tip body and flow control element is provided. The flow control element includes a pre-orifice through which fluid can enter a primary fluid passage of the spray tip body. First and second discharge orifices are provided in a dome-shaped end wall of the spray tip body with each of the first and second discharge orifices being arranged on a respective one of opposing first and second sides of an apex of the dome-shaped end wall. Each of the first and second discharge orifices having an elongated slot-like configuration that maintains a substantially constant width as the respective discharge orifice extends from a first end to a second end and each and each extending a substantially equal distance to either side of the apex of the dome-shaped end wall.

Spray devices have long been used in the agricultural industry for spraying liquids onto the agricultural products. These liquids are frequently discharged from moving vehicles such as trucks or tractors. One issue with spraying of some volatile liquids used in agricultural applications such as pesticides, herbicides and fungicides is the production of fine particles (e.g., particles less than 150 microns) that can drift to, and thereby pollute, surrounding areas. Accordingly, spray devices that produce fewer fine particles are desirable in such applications. One example of such a spray device is an air induction spray nozzle. Air induction spray nozzles utilize air passages that draw air into the nozzle body with the liquid which slows the flow of liquid allowing larger liquid drops to form.
A related issue with spraying liquids from a moving vehicle is that speed of vehicle can change. For example, if the vehicle moves faster, the liquid must be pumped at a higher pressure in order to maintain the same application rate. But, increasing the pressure of the liquid being sprayed leads to smaller droplets and thus more undesirable spray drift.
Pulse width modulation is one way in which to avoid the need to adjust the pressure of the liquid being sprayed when the speed of the vehicle changes. Spray nozzles equipped with pulse width modulation alternate very quickly between open and closed flow conditions. Changing the amount of time the pulse width modulation equipped nozzle is open or closed allows the rate of flow to be adjusted without changing the pressure. However, with an air induction nozzle, the rapid change between open and closed flow conditions can cause the air entrapment into the nozzle to stop. When this happens, since it is the flow of liquid that draws the air into the nozzle, the air will not start back up as quickly as the liquid when the nozzle reopens leading to a period of bad flow through the nozzle that can result in poor spray distribution and decreased droplet size leading to unwanted drift.

Low drift, high efficiency spraying system


When a vibration-type actuator is in a non-driving period, at least one of a voltage amplitude and a phase difference of an alternate signal applied to an electrode of a piezoelectric element is set to be equal to a minimum value or a maximum value of a dead zone in terms of the voltage amplitude or the phase difference.

1. Field of the Invention
The present invention relates to a drive apparatus using a vibration-type actuator, an interchangeable lens, or an image pickup apparatus, for example, a drive apparatus of a vibration-type actuator suitable for driving a focus lens of a camera by using a wobbling operation.
2. Description of the Related Art
Various proposals have been made in terms of a vibration-type actuator capable of generating an elliptic motion on a particular point thereby driving an element (for example, see Japanese Patent Laid-Open No. 10-210775). FIG. 16 illustrates an example of a proposed structure.
As illustrated in FIG. 16, a vibrator of this vibration-type actuator includes an elastic element 1 made of a rectangular-shaped plate of a metallic material, and a piezoelectric element 2 bonded to a back surface of the elastic element 1. A plurality of protruding parts 3 are formed at particular positions on an upper surface of the elastic element 1. With this structure, when an alternate current (AC) voltage is applied to the piezoelectric element 2, a second-order bending vibration in a direction along longer sides of the elastic element 1 and a first-order bending vibration in a direction along shorter sides of the elastic element 1 occur simultaneously, which excite the protruding parts 3 to have an elliptic motion. In this situation, if there is a driven element 4 pressed into a contact with the protruding parts 3, the element 4 is driven linearly by the elliptic motion of the protruding parts 3.
The piezoelectric element 2 has two electrodes A1 and A2 separated from each other as illustrated in FIG. 17. When AC voltages V1 and V2 with an equal phase are applied to the two electrodes A1 and A2, a first-order bending vibration is excited such that the rectangular elastic element 1 has two nodes extending in the direction parallel to the longer sides as illustrated in FIG. 18A. When AC voltages V1 and V2 with opposite phases are applied to the two electrodes A1 and A2, a second-order bending vibration is excited such that the rectangular elastic element 1 has three nodes extending in the direction parallel to the shorter sides as illustrated in FIG. 18B. By exciting the elliptic motion on the protruding parts 3 by a combination of first-order and second-order bending vibrations (vibration modes) while pressing the driven element 4 into the contact with the protruding parts 3, it is possible to linearly drive the driven element 4.
The first-order bending vibration illustrated in FIG. 18A causes the protruding parts 3 to have a vibration whose amplitude varies in a direction perpendicular to a contact surface at which the driven element 4 is in contact with the protruding parts 3 (hereinafter such an amplitude will be referred to as a Z-axis amplitude). The second-order bending vibration illustrated in FIG. 18B causes the protruding parts 3 to have a vibration whose amplitude varies in a direction parallel to a direction in which the driven element 4 is driven (hereinafter such an amplitude will be referred to as an X-axis amplitude). Use of a combination of the first-order bending vibration and the second-order bending vibration makes it possible to excite the protruding parts 3 to have an elliptic motion as illustrated in FIG. 19. An ellipticity ratio of the elliptic motion is given by the ratio of the magnitude of the Z-axis amplitude and the magnitude of the X-axis amplitude. By changing the phase difference between the applied AC voltages V1 and V2, it is possible to change the magnitude of the X-axis amplitude. By changing the voltage amplitudes of the AC voltages V1 and V2, it is possible to change the magnitude of the Z-axis amplitude. Thus, it is possible to adjust the ellipticity ratio of the elliptic motion excited on the protruding parts 3.
By setting the frequency of the AC voltages applied to the piezoelectric element 2 so as to be closer to the resonance frequency of the vibrator, it is possible to increase the drive speed. By setting the frequency of the AC voltages applied to the piezoelectric element 2 so as to be more different from the resonance frequency of the vibrator, it is possible to reduce the drive speed. For example, in the basic structure of the vibration-type actuator illustrated in FIG. 16, there is a relationship between the drive frequency and the drive speed as shown in FIG. 20. That is, the actuator has a characteristic that the drive speed has its peak at the resonance frequency of the vibrator, and the drive speed decreases gradually as the drive frequency increases in a range higher than the resonance frequency but sharply as the drive frequency decreases in a range lower than the resonance frequency.
Thus, in the vibration-type actuator having such a characteristic, it is possible to control the speed (by the frequency) by changing the frequency of the two AC voltages V1 and V2 applied to the piezoelectric element 2. Furthermore, it is possible to control the speed (by the phase difference) by changing the phases of the AC voltages V1 and V2. Still furthermore, it is possible to control the speed (by the voltage) by changing the voltage amplitudes of the two AC voltages V1 and V2 applied to the piezoelectric element 2.
Thus, it is possible to control the speed of the vibration-type actuator by a combination of the control by the frequency, the control by the phase difference, and the control by the voltage.

Drive apparatus of vibration-type actuator, interchangeable lens, and image pickup apparatus using the same


A semiconductor device includes an active pattern protruding from a substrate, gate structures crossing over the active pattern, gate spacers on sidewalls of the gate structures, a source/drain region in the active pattern between the gate structures, and a source/drain contact on and connected to the source/drain region. The source/drain contact includes a first portion between the gate structures and being in contact with the gate spacers, a second portion on the first portion and not being in contact with the gate spacers, and a third portion on the second portion. A first boundary between the second and third portions is at the substantially same height as a top surface of the gate structure.

The inventive concepts relate to semiconductor devices and, more particularly, to semiconductor devices including fin field effect transistor devices and methods of forming the same.
Semiconductor devices may include an integrated circuit including metal-oxide-semiconductor field effect transistors (MOSFETs). As the sizes and design rules of semiconductor devices have been reduced, the sizes of MOSFETs have been scaled down. The operating characteristics of semiconductor devices may be degraded due to the scale-down of the MOSFETs. Thus, research is being conducted for the purpose of developing semiconductor devices that can overcome the limitations caused by increases in integration density.


A stateless-object method is provided for executing instructions. The method: establishes a central repository of states, cross-referencing state locations in memory, to identifiers; calls a first method; accesses a stateless-object in response to the first method, the stateless-object including an identifier and a second method; reads the identifier; uses the identifier to cross-reference the stateless-object's state location in the repository; accesses the located state; and, instantiates the second method in response to accessing the state. The central repository of states may cross-reference a first state to a first identifier, and the step of accessing the stateless-object includes accessing a plurality of stateless-objects in response to the first method, with each of the stateless-objects including the first identifier. Then, the step of locating the state of the stateless-object using the identifier includes locating the first state for each of the plurality of stateless-objects by using the first identifier.

1. Field of the Invention
This invention generally relates to object-oriented software environment and, more particularly, to a stateless-object method for executing programmable instructions.
2. Description of the Related Art
As noted in U.S. Pat. No. 6,134,559, Brumme et al., an object-oriented approach to programming provides advantages over conventional procedural programming approaches. For example, an object-oriented approach permits code reuse through inheritance, and modularity through encapsulation. There are many views as to what concepts define object oriented programming, and there are many terms and definitions for defining these concepts. In general, objects incorporate procedures, also called methods or operations, and data, also called attributes or properties. Objects are instantiated from, and described by structures known as classes or types. A class is a general abstract specification, and an object instantiated from a class is a specific concrete instance of the class.
A class consists of an interface and an implementation. The interface comprises variables and function declarations, wherein the variables represent the attributes of the type, and the function declarations specify methods for manipulating those attributes as well as performing other operations. The declaration specifies the name, return type, and argument, known collectively as the signature. The implementation refers to the actual code that implements the methods specified in the interface.
Object-oriented languages, such as the C++ language, permit the creation of special classes via inheritance. In general, inheritance is a mechanism for passing attributes and methods from a parent or base class to one or more child or derived classes. Inheritance permits code reuse because interfaces and implementations need not be duplicated in the child class. Instead, the interfaces and implementations may be incorporated in any child class through reference of the parent or base class.
In general, objects communicate through message passing mechanisms. An object, known as a client object, may call a method of another object. A client object invokes a method of another object by accessing the object via the defined interfaces. Thus, to invoke a method in an object or to query an object, the client object requires knowledge of the signatures of the methods in the interface of the target object. The client object calls the methods and passes the appropriate parameters. For example, to obtain the value of an attribute in an object, a client object calls a method, via an interface, to obtain the value.
As noted in US Publication 2004/0177093, Mullins, a frequent approach for accessing data stores involves writing and embedding custom access code within an object application needing the access. This approach is generally limited to having the custom code access only a single relational table within a relational database or similar construct within any other data store. Under the circumstances where a developer has control over the design and creation of a data store from its inception, it is possible to design and store meaningful information in a single table. Such design opportunities are usually rare, however.
Generally, the methods for producing persistence for a data object, complex data object, or a data store conflict with the goals of producing pure object application models where the object models do not include persistence objects or persistence byte code. Particular difficulties exist in a distributed environment since an object application model may exist in one or more of a computer's memory, an application data store and an application information storage repository that may be independent of the data store organization or object definitions.
Persistence problems arise with the creation, access, changing, or deleting of an object application model that utilizes data stores. The object application model may be distributed over multiple physical computer machine locations or even distributed over multiple Internet website locations that may be independent of the data stores. The object application model may utilize a different set of data objects or different set of definitions for relationships between data objects than that of one or more of its data sources. In most situations, the respective structures of the data sources and of the object applications model simply do not conveniently allow for mapping, accessing, or changing of an overall schema of application data objects as well as any associated definitions of relationships between two or more data objects or elements within a data object.
Relationships may exist between a data object and one or more of the other data objects found in the object application model or in a data object of the data source. A relationship between one data object and another data object or with a data source may be member selected from the group of three relationship types consisting of 1 to 1 (1-1), 1 to many (1-M) or many to many (M-M). Complex combinations of these relationships may exist as a data object relationships definition for a given data object.
Objects may logically span multiple relational tables or multiple object databases, and may even be distributed over a logical computer system involving multiple physically independent computer systems or even multiple website locations. Creating, accessing, maintaining or updating an object application model can require working with multiple translation modules and require tedious and repetitive updating of multiple individual computer systems or multiple data sources in order to do useful work and keep the object application model synchronized. Such approaches are both costly and unwieldy in terms of computing and development resources.
Data objects of an object application model are often a feature of an object programming applications, where information is obtained from a data source and the data is defined as a data object (e.g., as a JAVA class) for use with another computer application. In practice, a data object or model of data objects may exist only in the random access memory of a computer memory system, or may be saved to either a data source or to some other type of retrievable information repository. A programmer or administrator of an object data application cannot easily access or track the overall model or diagram of data objects for an object application model or some of its specific elements. Unfortunately, tools for accessing and persisting data objects and associated data object relationships of a complex data object graph model have not been well implemented in the field of object language programming.
A computer application can execute one or more of the following non-limiting actions with respect to one or more of the members selected from the group consisting of data, a data object, and a data object definition: access data, change data, create data, create a new relationship between one or more data objects by creating or changing at least one data object relationship definition, change or delete a relationship between one or more data objects by changing or deleting at least one data object relationship definition, access a data object relationship definition and use its parameters to access a data source or a data object, and access one or more data object relationship definitions or data objects to create a new data object or data object relationship. Any changes executed by a computer application with respect to one or more of the members selected from the group consisting of data, data object or data object definition may need to be properly persisted (permanently stored) to preserve any changes to one or more of the members selected from the group consisting of data, a data object and a data object definition.
"Instance" as referred to herein is a single occurrence of a software logical element in the memory of a computer system, such as a "class", an "object", a "data object", and the like. This is analogous to the occurrence of a logical memory unit representing a row of data in common practice. "Class" as referred to herein is a logic unit in a computer application or a computer software program where the application or program is based upon an objected oriented programming language (e.g., JAVA). In practice, a class is a logical unit used as a logical template in an object oriented language from which to allocate new instances of objects. "Object" as used herein is a general term referring to a logic unit in a computer application or a computer software program where the application or program is based upon an object-oriented programming language (e.g., JAVA). The term "object" may ordinarily be used interchangeably with the term "class" as a template or as an instance depending on the context. As used herein, "Data object" represents the concept of the occurrence of an object that holds data within a specific computer application domain and is likely to have its contents stored in a persistent data source of a computer system (e.g., a database server, a binary file, a text file, or even in a combination of two or more of such a persistent data sources of a computer system). A data object may exist as an independent data object without any relationship to any other data object or it may have one or more relationships with itself or with one or more other data objects. "Navigation", "navigating" or "navigated" refers to an action implementing at least one object to interact with a set of related objects for a certain purpose, such as creation, access, insertion, modification and deletion of an object, or of one of its relationships.
As noted above, many software systems are modeled using object-oriented methodologies, where objects represent real-world objects in the problem domain. These modeled objects possess methods and information about the object, referred to as "state". State data can be, for example, the object's name, its color, or its location. The actual state information is stored within the object itself Therefore, if the user of the system creates two objects, both representing the same physical object, it is possible to change the state of one object, while leaving the other object's state unchanged. This results in the problem of having an inconsistency between multiple modeled objects' state information. This is usually addressed by maintaining complex relationships between objects to ensure that the user gets a reference to the same existing object and, therefore, the same state. In systems where the lifetime of the objects depends on those external references, it becomes quite difficult to manage the lifetime correctly, to avoid circular references, to persist the system state, or to minimize the working set of the application.
System persistence becomes difficult because each object must save its state, but also, the complex relationships between objects must be persisted as well. This problem is usually addressed by giving each object unique identifiers, and persisting references to the same object as the object's identifier. But a framework must be in place to support this as transparently as possible to the user. This issue also applies to remote objects, because all the dependent objects must be remoted as well. Also, since the entire graph of objects is eventually instantiated during the system's lifetime, the working set in memory can become quite large.
It would be advantageous if programmable instructions could distinguish and manipulate an object's state, apart from the object itself


A fuel injection control system for an internal combustion engine is provided which is designed to perform pilot injection of fuel into the engine through a fuel injector prior to main injection. The system monitors a combustion state parameter representing a combustion state of the fuel within a combustion chamber of the engine which has been sprayed in the event of the pilot injection. When the combustion state parameter is determined as lying out of a stable combustion range where the fuel is to burn stably, the system changes the number of pilot injections to be executed prior to the main injection and/or the quantity of the fuel to be sprayed in each pilot injection, thereby enhancing the ignitability of the fuel in the pilot injection.

1. Technical Field
This disclosure relates generally to a fuel injection control system for internal combustion engines which is designed to perform multiple injections of fuel into the engine and ensure the stability of burning of the fuel.
2. Background Art
Multi-injection systems are known which are engineered to spray fuel into an internal combustion engine (which will be typically called pilot injection) just before a main injection event to facilitate the ignition of sprayed fuel, thus reducing engine noise and consumed quantity of fuel. The pilot injection is to spray an amount of fuel much smaller than that in the main injection one or several times per stroke in the engine. The use of fuel that is low in cetane number may, therefore, cause the ignition delay to increase, thus resulting in a decrease in burned amount of fuel sprayed in the pilot injection or misfire thereof.
Japanese Patent First Publication No. 2009-299496 discloses a multi-pilot injection system which works to control a time interval between events of the pilot injections. Specifically, the multi-pilot injection system is designed to determine the pilot-to-pilot injection interval so that a spray of fuel, as produced by a latter one of two consecutive pilot injections, may be out of overlap with the cool flame, as produced by the former one, thereby establishing full growth of the cool flame to ensure the stability of burning of a desired amount of fuel in each pilot injection.
The above multi-pilot injection system, however, is engineered on the assumption that the sprayed fuel must be burned. Accordingly, when the ambient temperature is low, the atmospheric pressure is low, or the cetane number of fuel used is low, that is, when the ignitability of the fuel is low, it may result in lack in ignition of the fuel, which leads to an increase in unburned amount of fuel in the events of the pilot injection.

Fuel injection control system for internal combustion engine


A lightning-arresting system includes a lightning rod and an underground conductive network connected to the rod. The network includes a plurality of rectangular meshes or radially extending lines. The network is laid under a structure protected from lightning strikes. The coverage area of the network is greater than the building area of the structure to be protected.

1. Field of the Invention
The present invention generally relates to a system for avoiding lightning strikes. In particular, it relates to a lightning arresting system including a lightning rod and a conductive underground network connected to the rod.
2. Description of the Related Art
As is known, lightning occurs when a region of the atmosphere acquires a potential difference great enough to overcome the resistance of the air. Specifically, when lightning occurs, an electric dipole structure is produced in a cloud in a manner such that a large net-positive charge exists in the upper region of the cloud and a large net-negative charge in the lower region, as shown in FIG. 1. (To be precise, there exists a small net-positive charge in the lowest region of the cloud.)
A cloud-to-ground flash includes at least two strokes: a leader stroke and a return stroke. A leader stroke (carrying a negative charge) passes from cloud to ground.
The leader stroke is often stepped and has many branches extending out from the main channel. As it nears the ground, it induces an opposite charge at the point AP to be struck (called xe2x80x9cantipole pointxe2x80x9d hereinafter). Then, a return stroke (carrying a positive charge) from ground to cloud is generated through the main channel.
The two strokes will meet at a certain height above the ground. At this juncture, the cloud is short-circuited to the ground and a highly luminous return stroke passes through the channel to the cloud. A typical lightning flash involves a potential difference between cloud and ground of several hundred million volts, with peak currents on the order of 20,000 amperes.
Lightning strikes are deadly dangerous so that lightning rods are often used for protecting structures from being struck. As shown in FIG. 1, a lighting rod 1, which is made of copper for example, is usually disposed at a high point on a structure ST to be protected. The lighting rod 1, connected to the ground GR by low-resistance cables 2, is expected to intercept flashes and transmit their current to the ground safely.
The conventional lightning rod 1 is simply put at the top of the structure ST since it is uncritically believed that lightning tends to strike the highest object in the vicinity. In this connection, a theory says that a lightning rod can provide a cone of protection whose ground radius approximately equals its height above the ground (that is, the protection angle is about 45 degrees.) Actually, however, structures are sometimes struck and damaged by lightning, even though they are within the protection cone. This shows that conventional lighting rods are not reliable enough to protect structures from lighting strikes.
The present invention has been proposed under the circumstances described above. The inventor of the present invention is of the opinion that the cause of the failure of the conventional lightning rods to intercept lightning resides in the uncritically simple grounding manner.
It is, therefore, an object of the present invention to provide a lightning-arresting system designed to provide more reliable protection against lightning than is conventionally possible.
According to the present invention, there is provided a lightning-arresting system including a lightning rod and an underground conductor connected to the rod, wherein the underground conductor is spread to cover a protection area.
Preferably, the underground conductor may include a conductive network.
Preferably, the network may include a plurality of rectangular meshes each having a side length which is no greater than 1 meter.
Preferably, the plurality of rectangular meshes may include meshes different in size from each other.
Preferably, the meshes different in size may include an inner mesh and an outer mesh, wherein the inner mesh is greater than the outer mesh.
The lightning-arresting system may further include a connection cable which connects the lightning rod to the underground conductor. The connection cable may be connected to the center of the underground conductor.
The lightning-arresting system may further include a conductive post which connects the lightning rod to the underground conductor. The conductive post may be one of the vertical steel supports of the structure to be protected from lightning.
In the above case, the underground conductor may be formed with an opening for avoiding interference with the conductive post.
Preferably, the underground conductor may be laid under the structure to be protected, wherein the underground conductor is larger than the building area of the structure.
The lightning-arresting system of the present invention may further include a common connection point to which the lightning rod is connected. In this case, the underground conductor may include a plurality of linear conductive members or lines each extending radially from the common connection point.
Preferably, each conductive line may include some branches.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.

Lightning-arresting system with underground network