The present invention provides a positive photoresist composition including (A) an alkali-soluble resin and (B) a photosensitizer, and the ingredient (B) is a quinonediazide ester of, for example, 2,6-bis[4-hydroxy-3-(2-hydroxy-3,5-dimethylbenzyl)-2,5-dimethylbenzyl]-4-methylphenol, where the average degree of esterification of 20% to 80%.

1. Field of the Invention
The present invention relates to positive photoresist compositions which can form a variety of resist patterns such as dense patterns, isolation patterns, and dot patterns with good shapes under the same exposure conditions.
2. Description of the Related Art
Logic integrated circuits (ICs) have highly added values and have received attention in recent years. In production of highly integrated logic ICs where a high definition of not more than half a micron is required, demands have been made to provide photoresist compositions which can form resist patterns including various patterns such as dense patterns, isolation patterns, and dot patterns with good shapes.
In addition, such photoresist compositions are required to form individual resist patterns with good shapes even under the same exposure conditions.
However, conventional photoresist compositions cannot satisfactorily form isolation patterns or dot patterns even though they satisfactorily form dense patterns. Even if they can form such patterns, the resulting individual patterns have greatly varied focal depth range properties under the same exposure conditions. The exposure conditions or mask pattern dimensions must be therefore changed or adjusted depending on the shapes of patterns to obtain satisfactory patterns.
In this connection, Japanese Patent Laid-Open No. 6-167805 (conventional technology 1) and Japanese Patent Laid-Open No. 7-168355 (conventional technology 2) each disclose quinonediazide esters having specific structures as photosensitizers, and describe high-definition positive photoresist compositions containing the esters.
However, such positive photoresist compositions as concretely described in the conventional technologies 1 and 2 cannot form a variety of resist patterns with good shapes without changing exposure conditions.
Japanese Patent Laid-Open No. 9-110751 (conventional technology 3) describes phenol compounds shown by a wide-ranging general formula, and mentions that quinonediazide esters of the phenol compounds are useful as photosensitizers.
However, the conventional technology 3 lacks concrete description of esters according to the present invention. In addition, the conventional technology 3 describes a process for synthesizing a pentanuclear phenol compound, but this process is liable to form by-products and a target compound cannot be isolated in a high yield.
Accordingly, it is an object of the present invention to provide a positive photoresist composition which can form dense patterns, isolation patterns, dot patterns, and other various resist patterns with good shapes even under the same exposure conditions, and has satisfactory focal depth range properties in the formation of ultrafine resist patterns of not more than half a micron.
Another object of the invention is to provide a process for synthesizing a phenol compound shown by the following formula (I) in a high yield with minimized formation of by-products.
After intensive investigations, the present inventors found that a positive photoresist composition containing a quinonediazide ester of a compound of the following formula (I) in which the ester has an average degree of esterification of 20% to 80% can form dense patterns, isolation patterns, dot patterns, and other various resist patterns with good shapes even under the same exposure conditions and has satisfactory focal depth range properties.
Specifically, the invention provides, in an aspect, a positive photoresist composition including (A) an alkalisoluble resin, and (B) a photosensitizer. In this composition, the photosensitizer (B) includes a quinonediazide ester of a compound shown by the following formula (I), and the quinonediazide ester has an average degree of esterification of 20% to 80%:
wherein each of R1 to R7 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
The invented positive photoresist composition may include a quinonediazide ester of 2,6-bis[4-hydroxy-3-(2-hydroxy-3,5-dimethylbenzyl)-2,5-dimethylbenzyl]-4-methylphenol shown by the following formula (II) as the ingredient (B):
The invented positive photoresist composition preferably includes a quinonediazide ester of a compound shown by the following formula (III) as the ingredient (B):
wherein each of x and y is, identical to or different from each other, an integer of 0 or 1.
The invention provides, in a further aspect, the positive photoresist composition wherein the photosensitizer (B) includes a quinonediazide ester of a compound shown by the following formula (VI):
each of R1 to R9 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
The invented positive photoresist composition may include a quinonediazide ester of 2,6-bis[4-hydroxy-3-(2-hydroxy-4,6-dimethylbenzyl)-2,5-dimethylbenzyl]-4-methylphenol shown by the following formula (VII) as the ingredient (B):
In another aspect, the invention provides a process for synthesizing a polyphenol compound. This process includes the steps of adding, in the presence of an acid catalyst, a solution of a methylol-group-containing compound of the following formula (V) in an organic solvent:
wherein each of R3 to R7 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, to a phenol compound shown by the following formula (IV):
wherein each of R1 and R2 is, identical to or different form each other, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, or to a solution of the phenol compound in an organic solvent, and performing a reaction to yield a polyphenyl compound shown by the following formula (I):
wherein each of R1 to R7 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
In the above process, the organic solvents for use in dissolving the phenol compound and the methylol-group-containing compound are preferably good solvents for the polyphenol compound shown by the formula (I).
Each of the invented positive photoresist compositions may further include (C) a sensitizer (intensifier).
In the invented positive photoresist compositions, the proportion of the photosensitizer (B) may range from 10% to 60% by weight relative to the total weight of the ingredient (A) and the ingredient (C), where the ingredient (C) is added according to necessity.
Preferably, in the invented positive photoresist compositions, the quinonediazide ester may have an average degree of esterification of 40% to 60%.
[(A) Alkali-soluble Resin]
Alkali-soluble resins for use as the ingredient (A) are not limited and can be chosen from those generally used as film-forming substances in positive photoresist compositions. Of these resins, condensates of aromatic hydroxy compounds and aldehydes or ketones, polyhydroxy styrenes and derivatives thereof are preferable.
Such aromatic hydroxy compounds include, but are not limited to, phenol, m-cresol, p-cresol, o-cresol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, and other xylenols; m-ethylphenol, p-ethylphenol, o-ethylphenol, 2,3,5-trimethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol, 33-tert-butylphenol, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, and other alkyl-substituted phenols; p-methoxyphenol, m-methoxyphenol, p-ethoxyphenol, m-ethoxyphenol, p-propoxyphenol, m-propoxyphenol, and other alkoxy-substituted phenols; o-isopropenylphenol, p-isopropenylphenol, 2-methyl-4-isopropenylphenol, 2-ethyl-4-isopropenylphenol, and other isopropenyl-substituted phenols; phenylphenol, and other aryl-substituted phenols; 4,4xe2x80x2-dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone, pyrogallol, and other polyhydroxyphenols. Each of these compounds can be used alone or in combination.
The aldehydes include, but are not limited to, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, butyraldehyde, trimethylacetaldehyde, acrolein (acrylaldehyde), crotonaldehyde, cyclohexanecarbaldehyde, furfural, furylacrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, xcex1-phenylpropylaldehyde, xcex2-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, and cinnamaldehyde. Each of these aldehydes can be used alone or in combination. Of these aldehydes, formaldehyde is desirable for its availability. Particularly, to improve heat resistance, the combination use of a hydroxybenzaldehyde and formaldehyde is preferred.
The ketones include, for example, acetone, methyl ethyl ketone, diethyl ketone, and diphenyl ketone. Each of these ketones may be used alone or in combination. Further, an appropriate combination of an aldehyde and a ketone can be employed.
The condensate of an aromatic hydroxy compound and an aldehyde or a ketone can be prepared in the presence of an acidic catalyst according to a known technique. Such acidic catalysts include, but are not limited to, hydrochloric acid, sulfuric acid, formic acid, oxalic acid, and p-toluenesulfonic acid.
The polyhydroxystyrenes and derivatives thereof include, but are not limited to, vinylphenol homopolymers, copolymers of vinylphenol and a copolymerizable comonomer. Such comonomers include, for example, acrylic acid derivatives, acrylonitrile, methacrylic acid derivatives, methacrylonitrile, styrene, xcex1-methylstyrene, p-methylstyrene, o-methylstyrene, p-methoxystyrene, p-chlorostyrene, and other styrene derivatives.
Of these alkali-soluble resins for use in the present invention as the ingredient (A), alkali-soluble novolak resins having a weight average molecular weight (Mw) of about 2000 to 20000, and typically about 3000 to 12000 are preferred. Among them, alkali-soluble novolak resins obtained by a condensation reaction of m-cresol and p-cresol with formaldehyde, or alkali-soluble novolak resins obtained by a condensation reaction of m-cresol, p-cresol, 2,3,5-trimethylphenol with formaldehyde are typically preferred. These alkali-soluble novolak resins can produce positive photoresist compositions having a high definition and a wide exposure margin.
[(B) Photosensitizer]
In the invention, quinonediazide esters of the compounds of the following formula (I) are used as the photosensitizer (B):
wherein each of R1 to R7 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
Of these quinonediazide esters, preferred are quinonediazide esters of a compound of the following formula (II):
or of a compound of the formula (III):
wherein each of x and y is, identical to or different from each other, an integer of 0 or 1.
Also, quinonediazide esters of of compounds of the formula (VI) are preferred:
wherein each of R1 to R9 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
Of these quinonediazide esters, a quinonediazide ester of a compound of the following formula (VII) is preferred.
In the compound of the formula (III), there are three isomers, in which x=y=1, x=0 and y=1, and x=y=0.
The polyphenol compound of the formula (I) should be preferably synthesized by the following process to obtained the polyphenyl compound of the formula (I) in a high yield and to minimize the formation of by-products. Specifically, the polyphenol compound of the formula (I) should be preferably synthetically obtained by adding, in the presence of an acid catalyst, a solution of a methylol-group-containing compound of the following formula (V) in an organic solvent:
wherein each of R3 to R7 is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, to a phenol compound shown by the following formula (IV):
wherein each of R1 and R2 is, identical to or different form each other, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, or to a solution of the phenol compound in an organic solvent, and performing a reaction.
When the phenol compound is solid at ordinary temperature, the phenol compound should be preferably used in the form of a solution in an organic solvent.
Organic solvents for use in dissolving the phenol compound or the methylol-group-containing compound are preferably good solvents for the polyphenol compound of the formula (I). As such solvents, xcex3-butyrolactone and mixtures of xcex3-butyrolactone with alcohols are preferred.
To minimize the formation of by-products and to obtain the target polyphenol compound in a high yield, it is preferred to add the methylol-group-containing compound as small portions as possible to large amounts of the phenol compound. In the invention, the methylol-group-containing compound can be quantitatively added in trace portions by using a solution of a methylol-group-containing compound which is solid at ordinary temperature.
By using a good solvent for the polyphenol compound as a reaction solvent, the reaction can be performed in a homogenous solution, and the formation of by-products and the remaining of unreacted materials can be suppressed to yield the polyphenol compound in a higher yield.
The more the proportion of the phenol compound relative to the methylol-group-containing compound is, the less by-products are formed. However, if excessively large amounts of the phenol compound is used, the target polyphenol compound cannot be significantly isolated from the material phenol compound. The proportion of the phenol compound is therefore preferably 2 to 50 moles, and more preferably 6 to 16 moles relative to 1 mole of the methylol-group-containing compound.
The reaction product (polyphenyl compound) can be taken out from a reaction system by putting a reaction mixture into large amounts of a poor solvent such as water to precipitate the reaction product.
The precipitated reaction product is separated by filtration, is recrystallized with a solvent such as butyl acetate, and the obtained crystal is washed with, for example, toluene and is dried to yield the target polyphenol compound.
Quinonediazide esters can be obtained by subjecting the polyphenol compound of the formula (I) to a condensation reaction (an esterification reaction) with a 1,2-napthoquinonediazidesulfonyl halide. Such 1,2-napthoquinonediazidesulfonyl halides include, for example, 1,2-naphthoquinonediazide-4-sulfonyl halides and 1,2-napthoquinonediazide-5-sulfonyl halides.
The esterification reaction can be usually performed in an organic solvent in the presence of a basic condensing agent. Such organic solvents include, for example, dioxane, N-methylpyrrolidone, and dimethylacetamide, and such basic condensing agents include, for example, triethylamine, alkali carbonates or alkali hydrogencarbonates.
The esterification reaction should be preferably performed in such a manner as to achieve an average degree of esterification of 20% to 80%. To this end, the proportion of the 1,2-naphthoquinonediazidesulfonyl halide is preferably 1 to 4 moles, and more preferably 2 to 3 moles relative to 1 mole of the compound of the formula (I). The average degree of esterification well agrees with the proportions of individual ingredients and can be easily calculated from the added amount and unreacted amount of the 1,2-naphthoquinonediazidesulfonyl halide.
The average degree of esterification more preferably falls in a range from 40% to 60%. Within this range, the resulting photoresist composition can more advantageously form dense, isolation and dot resist patterns with good shapes under the same exposure conditions. If the average degree of esterification is less than 20%, a film residual rate of unexposed areas and definition are markedly decreased. In contrast, if it exceeds 80%, a sensitivity is markedly decreased.
The photosensitizer (B) for use in the invention may further comprise other quinonediazide esters to improve the sensitivity and definition. Such quinonediazide esters include, but are not limited to, quinonediazide esters of a polyphenol compound of the following formula (VIII):
wherein each of R10 to R17 is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group; each of R18 to R20 is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Q is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cyclic ring having 3 to 6 carbon atoms as members as combined with R18, or a residue of the following formula (IX); each of a and b is an integer of 1 to 3; d is an integer of 0 to 3; and n is an integer of 0 to 3:
wherein each of R21 and R22 is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group; and c is an integer of 1 to 3. Concretely, preferred additional quinonediazide esters of polyphenol compounds include, for example, quinonediazide esters of: 2,4-bis(3,5-dimethyl-4-hydroxybenzyl)-5-hydroxyphenol, 2,6-bis(2,5-dimethyl-4-hydroxybenzyl)-4-methylphenol, and other linear trinuclear compounds; bis[2,5-dimethyl-3-(4-hydroxy-5-methylbenzyl)-4-hydroxyphenyl]methane, bis [2,5-dimethyl-3-(4-hydroxybenzyl)-4-hydroxyphenyl]methane, bis[3-(3,5-dimethyl-4-hydroxybenzyl)-4-hydroxy-5-methylphenyl]methane, bis[3-(3,5-dimethyl-4-hydroxybenzyl)-4-hydroxy-5-ethylphenyl]methane, bis[3-(3,5-diethyl-4-hydroxybenzyl)-4-hydroxy-5-methylphenyl]methane, bis[3-(3,5-diethyl-4-hydroxybenzyl)-4-hydroxy-5-ethylphenyl]methane, bis[2-hydroxy-3-(3,5-dimethyl-4-hydroxybenzyl)-5-methylphenyl]methane, bis[2-hydroxy-3-(2-hydroxy-5-methylbenzyl)-5-methylphenyl]methane, bis[4-hydroxy-3-(2-hydroxy-5-methylbenzyl)-5-methylphenyl]methane, and other linear tetranuclear compounds; 2,4-bis[2-hydroxy-3-(4-hydroxybenzyl)-5-methylbenzyl]-6-cyclohexylphenol, 2,4-bis[4-hydroxy-3-(4-hydroxybenzyl)-5-methylbenzyl]-6-cyclohexylphenol, and other linear pentanuclear compounds; and other linear polyphenol coin pounds; tris(4-hydroxyphenyl)methane, bis(4-hydroxy-3 ,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-2,4-dihydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2,4-dihydroxyphenylmethane, bis(4-hydroxyphenyl)-3-methoxy-4-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-3-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-3,4-dihydroxyphenylmethane, bis(3-cyclohexyl-6-hydroxyphenyl)-3-hydroxyphenylmethane, bis(3-cyclohexyl-6-hydroxyphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-6-hydroxyphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-6-hydroxy-4-methylphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-6-hydroxy-4-methylphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-6-hydroxy-4-methylphenyl)-3,4-dihydroxyphenylmethane, bis(4-hydroxy-2,3,5-trimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,3,5-trimethylphenyl)-3-hydroxyphenylmethane, bis(4-hydroxy-2,3,5-trimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-2,3,5-trimethylphenyl)-3,4-dihydroxyphenylmethane, bis(4-hydroxy-2,3,5-trimethylphenyl)-4-hydroxy-3-methoxyphenylmethane, and other trisphenolic polyphenol compounds.
The proportion of the quinonediazide ester of the compound of the formula (I) should be preferably 10% by weight or more, and more preferably 50% by weight or more based on the total weight of the ingredient (B). Within this range, the above advantages of the invented composition can be preferably obtained.
The proportion of the ingredient (B) in the invented composition is preferably 10% to 60% by weight, and more preferably 20% to 50% by weight relative to the total weight of the alkali-soluble resin ingredient (A), and a sensitizer (intensifier) ingredient (C) added according to necessity as mentioned below. If the proportion of the ingredient (B) is less than the above range, images in exact accordance with patterns cannot be obtained, and transferring property is deteriorated. In contrast, if the proportion exceeds the above specified range, sensitivity and uniformity of the resulting resist film tend to be deteriorated to thereby deteriorate definition.
[(C) Sensitizer (Intensifier)]
Sensitizers (intensifiers) for use as the ingredient (C) in the invention are not limited, and any known sensitizers can be used. Such sensitizers include, but are not limited to, polyphenyl compounds of the formula (VIII). Of these compounds, preferred compounds are, for example, bis(4-hydroxy-2,3,5-trimethylphenyl)-2-hydroxyphenylmethane, 1,4-bis[1-(3,5-dimethyl-4-hydroxyphenyl)isopropyl]benzene, 2,4-bis(3,5-dimethyl-4-hydroxyphenylmethyl)-6-methylphenol, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane,1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene, 1-[1-(3-methyl-4-hydroxyphenyl)isopropyl]-4-[1,1-bis(3-methyl-4-hydroxyphenyl)ethyl]benzene, 2,6-bis[1-(2,4-dihydroxyphenyl)isopropyl]-4-methylphenol, 4,6-bis[1-(4-hydroxyphenyl)isopropyl]resorcin, 4,6-bis(3,5-dimethoxy-4-hydroxyphenylmethyl)pyrogallol, 4,6-bis(3,5-dimethyl-4-hydroxyphenylmethyl)pyrogallol, 2,6-bis(3-methyl-4,6-dihydroxyphenylmethyl)-4-methylphenol, 2,6-bis(2,3,4-trihydroxyphenylmethyl)-4-methylphenol, and 1,1-bis(4-hydroxyphenyl)cyclohexane. Among them, bis(4-hydroxy-2,3,5-trimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, 2,4-bis(3,5-dimethyl-4-hydroxyphenylmethyl)-6-methylphenol, 4,6-bis[1-(4-hydroxyphenyl)isopropyl]resorcin, and 1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene are typically preferred.
When the ingredient (C) is incorporated in the invented composition, the content of the ingredient (C) is preferably 5% to 50% by weight, and more preferably 10% to 35% by weight relative to the weight of the alkali soluble resin ingredient (A). The use of the sensitizer (intensifier) (C) within the above range is preferred to further improve exposure margin, definition, and focal depth range properties, and to provide a satisfactory sensitivity.
Where necessary, the invented composition may further comprise any of compatible additives including, for example, ultraviolet absorbents for inhibition of halation and surfactants for prevention of striation within a range not adversely affecting the advantages of the invention. Such ultraviolet absorbents include, for example, 2,2xe2x80x2,4,4xe2x80x2-tetrahydroxybenzophenone, 4-dimethylamino-2xe2x80x2,4xe2x80x2-dihydroxybenzophenone, 5-amino-3-methyl-1-phenyl-4-(4-hydroxyphenylazo)pyrazole, 4-dimethylamino-4xe2x80x2-hydroxyazobenzene, 4-diethylamino-4xe2x80x2-ethoxyazobenzene, 4-diethylaminoazobenzene and curcumin. Illustrative surfactants are available as Fluorade FC-430 and FC-431 (trade names, manufactured by Sumitomo 3M Ltd., Japan), F-TOP EF122A, EF122B, EF122C and EF126 (trade names, manufactured by Tochem Products Ltd., Japan), and other fluorine-containing surfactants.
The invented composition may preferably be used as a solution prepared by dissolving the ingredients (A), (B) and (C), and each of additional ingredients added according to necessity, in an appropriate solvent. Such solvents include solvents conventionally used for positive photoresist compositions, such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, and other ketones; ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monoacetate, propylene glycol monoacetate, diethylene glycol monoacetate, or their mono-methyl ethers, monoethyl ethers, monopropyl ethers, monobutyl ethers or monophenyl ethers, and other polyhydric alcohols and derivatives thereof; dioxane, and other cyclic ethers; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, and other esters. Each of these solvents can be used alone or in combination. Particularly preferred solvents are acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, and other ketones; ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, and other esters.
Practically, the invented composition may be used, for example, in the following manner. Each of the ingredients (A), (B) and (C), and other ingredients added according to necessity is dissolved in an appropriate solvent as mentioned above to yield a coating solution; the coating solution is then applied, using a spinner or the like, onto a substrate such as a silicon wafer or a substrate on which an antireflection coating has been formed, and is then dried to form a photosensitive layer; next, the photosensitive layer is irradiated and is exposed with an ultraviolet ray source such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, an arc lamp, or a xenon lamp, through a desired mask pattern, or irradiated with a scanning electron beam; and the exposed portions of the film are then dissolved and removed by dipping the substrate in a developer solution, for example, an alkaline aqueous solution such as a 1% to 10% by weight tetramethylammonium hydroxide (TMAH) aqueous solution, thus forming an image being in exact accordance with the mask pattern.

Positive photoresist composition and process and synthesizing polyphenol compound


A non-contact type load-dispatching equipment having a power supply side core and a receiving side core both provided with a plurality of teeth wound by winding, each of teeth top surfaces formed by respective teeth is oppositely positioned to each other via a gap being magnetically connected for supplying power without contact at the time of power supply, wherein. teeth top surfaces of respective teeth of the power supply side core and receiving side core are disposed oppositely on the respective circumferences with a gap therebetween which allows coupling-uncoupling of the cores therethrough; PA0 light signal generating circuit for generating light signals which indicate receiving side voltages is provided in the power receiving side; PA0 voltage signal generation circuit which generates corresponding voltage signals on receiving the light signals and cut-off circuit for cutting off power supply when the generated voltage signal is lower than the predetermined value, where the voltage signal generation and cut-off circuits are provided in the power supply side.

1. Field of the Invention
The present invention relates to non-contact type load-dispatching equipment which supplies power to an autonomous mobile vehicle which is used in an environment wherein power supply by connecting an electrode is difficult, or to an autonomous mobile vehicle used in an ordinary environment wherein contact power supply by connecting an electrode or power supply by a trailing cable (lead wire) to a relatively moving body is difficult due to such reasons as damage, wear, or fatigue, for example, to an electric driverless transportation vehicle or the like which transports goods in a plant.
2. Description of the Related Art
A non-contact type load-dispatching equipment of the conventional type, split core type equipment using magnetic coupling, is known, which type is usually structured to a model with the shell type transformer shown in FIGS. 1A and 1B or to a model with a core type transformer shown in FIGS. 2A and 2B.
These were provided, for example, as shown in Japanese Patent Laid-Open 58-74021 Gazette, for non-contact load-dispatching by coupling power supply and receiving portions with a small gap therebetween, the power supply portion comprising power supply side winding Wa, power supply side core A, power supply side coupler D, and the receiving portion comprising receiving side winding Wb, receiving side core B and receiving side coupler E.
Though there is equipment which supplies electric power from a fixed portion to a rotary portion without contacting thereto as disclosed in Japanese Utility Model Publication 55-15297 Gazette or in Japanese Patent Laid-Open 61-281508 Gazette, all such equipment supplies power to a rotary portion in rotating motion and is not applicable to the autonomous mobile vehicle like the non-contact type load-dispatching equipment which is the object of the present invention.
Therefore, in order to increase transmission magnetic flux within the range of the core material saturation magnetic flux density, it becomes necessary to increase the cross sectional area, thus structurally making it inevitable to make a large frame for the core.
Further, since magnetic flux tends to leak in a butting type coupling as described above, it has been difficult to improve transmission efficiency.

Load-dispatching apparatus having improved power supply cut-off


A method for diagnostic imaging with reduced contrast agent dose uses a deep learning network (DLN) [114] that has been trained using zero-contrast [100] and low-contrast [102] images as input to the DLN and full-contrast images [104] as reference ground truth images. Prior to training, the images are pre-processed [106, 110, 118] to co-register and normalize them. The trained DLN [114] is then used to predict a synthesized full-dose contrast agent image [116] from acquired zero-dose and low-dose images.

Many types of medical imaging use contrast agents to enhance the visualization of normal and abnormal structures. Examples include conventional angiography, fluoroscopy, computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI). It is often desirable to reduce the contrast agent dose in order to increase the safety of these agents. However, reduced dose reduces desired imaging enhancements, so this has not been possible.
For example, MRI is a powerful imaging technique providing unique information to distinguish different soft tissues and pathologies. Magnetic contrast agents with unique relaxation parameters are often administered to further boost the visibility of pathology and delineation of lesions. Gadolinium based contrast agents (GBCAs) are widely used in MRI exams because of their paramagnetic properties, for applications such as angiography, neuroimaging and liver imaging. However, although GBCAs are designed to avoid toxic release and have been widely applied in contrast enhanced MRI (CE-MRI) examinations to assist the diagnosis, there are several side effects resulting from GBCA administration. Therefore, there are many reasons why it would be advantageous to reduce the dosage of GBCA while preserving the enhanced contrast in MRI imaging. Similar problems are associated with administering contrast agents in other imaging modalities as well. Thus, it would be of benefit to be able to reduce the dose of contrast agents generally in diagnostic imaging techniques, without sacrificing the image enhancement benefits that the contrast agents provide.

Contrast dose reduction for medical imaging using deep learning

The Board of Trustees of the Leland Stanford Junior University


Methods for providing remote access to an application executing on a remote server. A client computer includes a client remote access program that is used to connect to a server remote access program. At the client computer, a client difference program having encoded data indicative of changes to the application since changes were last received from the server computer is generated and transmitted to the server remote access program. At the server computer, the client difference program is executed to update the application and a server difference program is generated having encoded changes to the application since the changes were last received from the client computer. The server difference program is transmitted to the client computer to update the application.

Healthcare institutions, such as hospitals and diagnostic clinics, utilize information systems such as Hospital Information Systems (HIS), Radiology Information Systems (RIS), Clinical Information Systems (CIS), Picture Archive and Communication Systems (P ACS), Library Information Systems (LIS), Electronic Medical Records (EMR), to name a few. Information stored and processed in such systems includes, for example, patient medical histories, imaging data, test results, diagnosis information, management information, and scheduling information. The information is stored centrally or divided at a plurality of locations of a computer network—typically comprising a client-server architecture. Healthcare practitioners access the patient information or other information at various time instants and locations using sophisticated software application programs to gather, analyze, manipulate, and store data.
For example, using a PACS workstation a radiologist performs an image reading for a diagnosis based on content of diagnostic images and reports the results electronically in a patient application file. Because of the large volume of data and intensive computing requirements, the software used to perform this task typically requires dedicated workstation hardware and high bandwidth network access to the diagnostic images. As a consequence, there is limited or no access to the diagnostic information and analysis capability off-site from the P ACS workstation. This limits the ability of radiologists, technicians, and other specialists who are not on-site to be able to gain access to the necessary software and data to provide timely diagnosis, for example, in an urgent situation.
Presently, this problem is typically overcome by providing remote network access to the screen or console of the workstation hardware, or by downloading sensitive data such as, for example, diagnostic data, to a remote system. In the first case, remote access software does not have any special knowledge of the application programs that are executed and are not able to optimize the presentation of the display of the application program to the user based on the state of the application program—resulting in inefficient use of network bandwidth and poor performance for the remote user. In the second case, the transmission of patient related information to an uncontrolled remote site is a security risk for such sensitive information, and furthermore, in the case of diagnostic imaging data, requires transmission of large amounts of information which is beyond the capacity of many networks.

This patent is subject to a terminal disclaimer.

Method and system for providing remote access to a state of an application program


According to a first exemplary embodiment, a wireless terminal may provide DC communication through an MN using an MCG over a first radio interface between the wireless terminal and the MN and through a SN using a SCG over a second radio interface between the wireless terminal and the SN. A split SRB may be configured for the wireless terminal using DC through the MCG with the MN and through the SCG with the SN and the wireless terminal may be configured to use the SCG for the split SRB without using the MCG for the split SRB. Responsive to detecting failure of the SCG while configured to use the SCG for the split SRB without using the MCG for the split SRB, an SCG failure information message regarding failure of the SCG may be transmitted to the master node using the MCG.

E-UTRAN supports Dual Connectivity (DC) operation whereby a multiple Rx/Tx UE (User Equipment) in RRC_CONNECTED is configured to use radio resources provided by two distinct schedulers, located in two eNBs connected via a non-ideal backhaul over the X2 interface (see 3GPP 36.300). eNBs involved in DC for a certain UE may assume two different roles. An eNB may either act as an MN (Master node) or as an SN (Secondary node). In DC, a UE may be connected to one MN and one SN.
In LTE DC, the radio protocol architecture that a particular bearer uses depends on how the bearer is setup. Three bearer types exist: MCG (Master Cell Group) bearer, SCG (Secondary Cell Group) bearer, and split bearers. RRC (Radio Resource Control) is located in MN and SRBs (Signaling Radio Bearers) are always configured as MCG bearer type and therefore only use the radio resources of the MN.
FIG. 1 is a block diagram illustrating a Long Term Evolution (LTE) DC User Plane (UP).
LTE-NR (New Radio) DC (also referred to as LTE-NR tight interworking) is currently being discussed for rel-15. In this context, significant changes from LTE DC include:                The introduction of split bearer from the SN (known as SCG split bearer);        The introduction of split bearer for RRC; and        The introduction of a direct RRC from the SN (also referred to as SCG SRB).
FIGS. 2 and 3 illustrate the UP and Control Plane (CP) architectures for LTE-NR tight interworking.
In the case that the master node is an LTE node and the secondary node as an NR node, the SN may be referred to as SgNB (where gNB is an NR base station), and the MN may be referred to as MeNB. In the case that the master node is an NR node and the secondary node is an LTE node, the secondary node may be referred to as SeNB, and the master node may be referred to as MgNB.
Split RRC messages may be used primarily to create diversity, and the sender can decide to either choose one of the links for scheduling the RRC messages, or it can duplicate the message over both links. In the downlink, path switching between the MCG or SCG legs or duplication on both is left to network implementation. On the other hand, for the uplink, the network configures the UE to use the MCG, SCG, or both legs. The terms "leg" and "path" are used interchangeably throughout this document.
With dual connectivity DC for a UE, improved handling of failure on one of the DC legs for the UE may be desired.

Methods responding to SCG failure in DC communications and related wireless terminals and network nodes


The present invention is directed to compounds, compositions, and use of compounds the structural Formula (I)

Peroxisome Proliferator Activated Receptors (PPARs) are members of the nuclear hormone receptor super family, which are ligand-activated transcription factors regulating gene expression. Various subtypes of PPARs have been discovered. These include, for example, PPARα, NUC1, PPARγ and PPARδ.
PPARα, PPARγ and PPARδ receptors have been implicated in diabetes mellitus, cardiovascular disease, obesity, Syndrome X and gastrointestinal disease, such as, inflammatory bowel disease. Syndrome X is the combination of symptoms which include hyperinsulemia combined with hypertension, elevated body weight, elevated triglycerides and elevated LDL.
Current PPAR agonist treatment for Syndrome X relates to the use of thiazolidinediones (TZDs) or other insulin sensitivity enhancers (ISEs). TZDs are a class of PPAR gamma agonists that have been shown to increase the sensitivity of insulin sensitive cells. Increasing insulin sensitivity rather than the amount of insulin in the blood reduces the likelihood of hypoglycemic coma. However, TZDs and ISEs have been associated undesirable clinical effects and improved clinical profiles are desired. Therefore, a need exists for new pharmaceutical agents having a desirable pharmacological profile. Such PPAR selective or dual selective agonist compounds are especially desirable when associated with a desirable safety profile and the desired effect in the treatment of diabetes and/or related clinical conditions.

Amide linker peroxisome proliferator activated receptor modulators


A surfboard bag hammock that is configured as a carrier receptacle and a hammock by having two different sized layers of material fastened together. The larger layer of material serves as the hammock and the smaller layer of material having a fastener lined opening serves as the carrier receptacle for an article, such as a surfboard. When the carrier receptacle is turned inside out the hammock is inserted and used as packing material before the article is placed within the carrier receptacle.

1. Field of the Invention
The present invention relates generally to carryalls and, more specifically, to a surfboard bag hammock that can be configured either as an article carrier or as a hammock by having two dissimilarly sized pieces of material fastened together forming a compartment there between with the larger material serving as hammock and the smaller material having a fastener lined opening serving as storage for an article placed therein with the novel element that when the article compartment is turned inside out the extra hammock material serves as padding and protection for the article within the article receptacle.
2. Description of the Prior Art
There are other carriers which provide for articles. While these carriers may be suitable for the purposes for which they where designed, they would not be as suitable for the purposes of the present invention as heretofore described.


Implantable medical devices (IMDs) and their various components, including flat electrolytic capacitors for same, and methods of making and using same and providing for outgassing of gases released during capacitor charge and discharge cycles are disclosed. A gas vent and liquid electrolyte barrier into the electrolyte fill tube lumen that is used to fill the interior case chamber with electrolyte and then needs to be closed to prevent leakage of electrolyte. The fill port is shaped to comprise a fill port tube having interior and exterior tube ends and a fill port ferrule intermediate the ends of the fill port tube and comprising a fill port ferrule flange extending trasversely to and away from the fill port tube. The fill port ferrule is mounted in an opening disposed in one of the case wall and the cover wall with the ferrule flange in seaing engagement therewith to locate the exterior tube end extending outwardly away from the fill port ferrule flange and the interior tube end within the interior case chamber. A microporous plug is injected into and fills the fill port lumen, the plug formed of a microporous material allowing the escape of gas released from the liquid electrolyte during capacitor charging while preventing escape of liquid or vaporized electrolyte.

This invention relates to implantable medical devices (IMDs) and their various components, including flat electrolytic capacitors for same, and methods of making and using same and providing for outgassing of gases released during capacitor charge and discharge cycles.
As described in the above-referenced parent application Ser. No. 09/103,843, and the provisional application that it claims priority from, a wide variety of IMDs are known in the art. Of particular interest are implantable cardioverter-defibrillators (ICDs) that deliver relatively high energy cardioversion and/or defibrillation shocks to a patient""s heart when a malignant tachyarrhythmia, e.g., atrial or ventricular fibrillation, is detected. Current ICDs typically possess single or dual chamber pacing capabilities for treating specified chronic or episodic atrial and/or ventricular bradycardia and tachycardia and were referred to previously as pacemaker/cardioverter/defibrillators (PCDs). Earlier developed automatic implantable defibrillators (AIDs) did not have cardioversion or pacing capabilities. For purposes of the present invention ICDs are understood to encompass all such IMDs having at least high voltage cardioversion and/or defibrillation capabilities.
Generally spealdng, it is necessary to employ a DC-DC converter within an ICD implantable pulse generator (IPG) to convert electrical energy from a low voltage, low current, electrochemical cell or battery enclosed within the IPG housing to a high voltage energy level stored in one or more high energy storage capacitor, as shown for example, in commonly assigned U.S. Pat. No. 4,548,209. The conversion is effected upon confirmation of a tachyarrhythrnia by a DC-DC xe2x80x9cflybackxe2x80x9d converter which includes a transformer having a primary winding in series with the battery and a secondary winding in series with the high energy capacitor(s) and an interrupting circuit or switch in series with the primary coil and battery that is periodically opened and closed during a charging cycle. Charging of the high energy capacitor is accomplished by inducing a voltage in the primary winding of the transformer creating a magnetic field in the secondary winding when the switch is closed. The field collapses when the current in the primary winding is interrupted by opening the switch, and the collapsing field develops a current in the secondary winding which is applied to the high energy capacitor to charge it. The repeated interruption of the supply current charges the high energy capacitor to a desired level of several hundred volts over a charging time of the charge cycle. Then, the energy is rapidly discharged from the high voltage capacitor(s) through cardioversion/defibrillation electrodes coupled to the IPG through ICD leads and arranged about or in a heart chamber or vessel if the tachyarrhythmia is confimed as continuing at the end of the charge time. The cardioversion/defibrilation shocks effected by discharge of such capacitors are typically in the range of about 25 to 40 Joules. The process of delivering cardioversion/defibrillation shocks in this way may be repeated if an earlier delivered cardioversion/defibrillation shock does not convert the tachyarrhythmia to a normal heart rhythm.
Energy, volume, thickness and mass are critical features in the design of ICD pulse generators that are coupled to the ICD leads. The battery(s) and high voltage capacitor(s) used to provide and accumulate the energy required for the cardioversion/defibrillation shocks have historically been relatively bulky and expensive. Presently, ICD IPGs typically have a volume of about 40 to about 60 cc, a thickness of about 13 mm to about 16 mm and a mass of approximately 100 grams.
It is desirable to reduce the volume, thickness and mass of such capacitors and ICD IPGs without reducing deliverable energy. Doing so is beneficial to patient comfort and minimizes complications due to erosion of tissue around the ICD IPG. Reductions in size of the capacitors may also allow for the balanced addition of volume to the battery, thereby increasing longevity of the ICD IPG, or balanced addition of new components, thereby adding functionality to the ICD IPG. It is also desirable to provide such ICD IPGs at low cost while retaining the highest level of performance. At the same time, reliability of the capacitors cannot be compromised.
Various types of flat and spiral-wound capacitors are known in the art, some examples of which are described as follows and/or may be found in the patents listed in Table 1 of the above-referenced parent patent application Ser. No. 09/103,843.
Prior art high voltage electrolytic capacitors used in ICDs have two or more anode and cathode layers (or xe2x80x9celectrodesxe2x80x9d) and operate at room or body temperature. Typically, the capacitor is formed with a capacitor case enclosing an etched aluminum foil anode, an aluminum foil or film cathode, and a Kraft paper or fabric gauze spacer or separator impregnated with a solvent based liquid electrolyte interposed therebetween. A layer of aluminum oxide that functions as a dielectric layer is formed on the etched aluminum anode, preferably during passage of electrical current through the anode. The electrolyte comprises an ion producing salt that is dissolved in a solvent and provides ionic electrical conductivity between the cathode and the aluminum oxide dielectric. The energy of the capacitor is stored in the electrostatic field generated by opposing electrical charges separated by the aluminum oxide layer disposed on the surface of the anode and is proportional to the surface area of the aluminum anode. Thus, to minimize the overall volume of the capacitor one must maximize anode surface area per unit volume without increasing the capacitor""s overall (i.e., external) dimensions. The separator material, anode and cathode layer terininals, internal packaging, electrical interconnections, and aligmnent features and cathode material further increase the thickness and volume of a capacitor. Consequently, these and other components in a capacitor and the desired capacitance limit the extent to which its physical dimensions may be reduced.
Some ICD IPGs employ commercial photoflash capacitors similar to those described by Troup in xe2x80x9cImplantable Cardioverters and Defibrillators,xe2x80x9d Current Problems in Cardiology, Volume XIV, Number 12, December 1989, Year Book Medical Publishers, Chicago, and as described in U.S. Pat. No. 4,254,775. The electrodes or anode and cathodes are wound spiral into anode and cathode layers separated by separator layers of the spiral. Anode layers employed in such photoflash capacitors typically comprise one or two sheets of a high purty (99.99%), porous, highly etched, anodized aluminum foil. Cathode layers in such capacitors are formed of a non-porous, highly etched aluminum foil sheet which may be somewhat less pure (99.7%) respecting aluminum content than the anode layers. The separator formed of one or more sheet or layer of Kraft paper saturated and impregnated with a solvent based liquid electrolyte is located between adjacent anode and cathode layers. The anode foil thickness and cathode foil thickness are on the order of 100 micrometers and 20 micrometers, respectively. Most commercial photoflash capacitors contain a core of separator paper intended to prevent brittle, highly etched aluminum anode foils from fracturing during winding of the anode, cathode and separator layers into a coiled configuration. The cylindrical shape and paper core of commercial photoflash capacitors limits the volumetric packaging efficiency and thickness of an ICD IPG housing made using same.
The aluminum anodes and cathodes of aluminum electrolytic capacitors generally each have at least one tab extending beyond their perimeters to facilitate electrical connection of all (or sets of) the anode and cathode layers electrically in parallel to form one or more capacitor and to make electrical connections to the exterior of the capacitor case. Tab terminal connections for a wound electrolytic capacitor are described in U.S. Pat. No 4,663,824 that are laser welded to feedthrough pin terminals of feedthroughs extending through the case. Wound capacitors usually contain two or more tabs joined together by crimping or riveting.
Flat electrolytic capacitors have also been disclosed in the prior art for general applications as well as for use in ICDs. More recently developed ICD IPGs employ one or more flat high voltage capacitor to overcome some of the packaging and volume disadvantages associated with cylindrical photoflash capacitors. For example, U.S. Pat. No. 5,131,388 discloses a flat capacitor having a plurality of stacked capacitor layers each comprising an xe2x80x9celectrode stack sub-assemblyxe2x80x9d. Each capacitor layer contains one or more anode sheet forming an anode layer having an anode tab, a cathode sheet or layer having a cathode tab and a separator for separating the anode layer from the cathode layer. In the ""388 patent, the electrode stack assembly of stacked capacitor layers is encased within a non-conductive, polymer envelope that is sealed at its seams and fitted into a chamber of a conductive metal, capacitor case or into a compartment of the ICD IPG housing, and electrical connections with the capacitor anode(s) and cathode(s) are made through feedthroughs extending through the case or compartment wall. The tabs of the anode layers and the cathode layers of all of the capacitor layers of the stack are electrically connected in parallel to form a single capacitor or grouped to form a plurality of capacitors. The aluminum anode layer tabs are gathered together and electrically connected to a feedthrough pin of an anode feedthrough extending trough the case or compartment wall. The aluminum cathode layer tabs are gathered together and electrically connected to a feedthrough pin of a cathode feedthrough extending through the case or compartment wall or connected to the electrically conductive capacitor case wall.
Many improvements in the design of flat aluminum electrolytic capacitors for use in ICD IPGs have been disclosed, e.g., those improvements described in xe2x80x9cHigh Energy Density Capacitors for Implantable Defibrillatorsxe2x80x9d presented by P. Lunsmann and D. MacFarlane at CARTS 96: 16th Capacitor and Resistor Technology Symposium Mar. 11-15, 1996, and at CARTS-EUROPE 96: 10th European Passive Components Symposium. Oct. 7-11, 1996, pp. 35-39. Further features of flat electrolytic capacitors for use in ICD IPGs are disclosed in U.S. Pat. Nos. 4,942,501; 5,086,374; 5,146,391; 5,153,820; 5,562,801; 5,584,890; 5,628,801; and 5,748,439, all issued to MacFarlane et al.
A number of recent patents including U.S. Pat. Nos. 5,660,737; 5,522,851; 5,801,917; 5,808,857; 5,814,082; 5,908,151; 5,922,215; 5,926,357; 5,930,109; 5,968,210 and 5,983,472, all assigned to the same assignee, disclose related flat electrolytic capacitor designs for use in ICDs. In several of these patents, internal alignent elements are employed as a means for controlling the relative edge spacing of the anode and cathode layers from the conductive capacitor case. In these patents, each anode layer and cathode layer is provided with an outwardly extending tab, and the anode and cathode tabs are electrically connected in common to a feedthrough pin and a step feature of the conductive capacitor case, respectively. The cathode tabs are gathered together against the step feature and ultrasonically welded together and to the step feature. In the ""357 patent, the anode tabs are laser welded to one end of an aluminum ribbon that is ultrasonically welded at its other end to an aluminum layer that is ultrasonically welded to the terminal pin. The feedthrough terminal pin is electrically isolated from and extends outside and away from the case to provide an anode connection pin. A cathode connection pin is attached to the case and extends outwardly therefrom. The anode and cathode connection pins are electrically connected into the DC-DC converter circuitry, but the attachment mechanism is not described in any detail.
The above-described electrolytic capacitors typically employ a liquid electrolyte that is injected into the case through a fill port or tube after the electrode stack assembly is nested within the case chamber, the electrical connections are made to the case or the feedthrough terminal pin, and the case cover or lid is hermetically sealed over the case opening to hermetically enclose the chamber and its contents. Such liquid electrolyte fill tubes or ports are described in U.S. Pat. Nos. 5,862,035 and 3,918,474, for example. Similarly, certain lead acid automotive batteries, have employed fill ports in their top surfaces that are normally upright for initially introducing and replenishing evaporation of acid electrolyte. In certain cases, the fill ports allow for the venting of hydrogen gases released during charging and discharging cycles, as disclosed in U.S. Pat. No. 5,449,574, for example. However, leakage can occur if such batteries are not kept upright.
Gases are also released during the charging and discharging cycles of various types of electrolytic capacitors including the above-described wound and flat aluminum anode and cathode layer electrolytic capacitors. In particular, hydrogen is released from the liquid electrolyte, and the gas builds up within the sealed capacitor case. Severe hydrogen accumulation can cause the capacitor case walls to swell outward and conceivably could cause the capacitor case to rupture at a laser weld seam or feedthrough. A variety of vent mechanisms have been provided through the capacitor case wall of various types of electrolytic capacitors that rupture or open when gas pressure reaches a threshold level as disclosed, for example, in U.S. Pat. Nos. 4,004,199; 4,074,417; 4,617,611; and 5,591,540. These approaches may be suitable in environments where the electrolyte can cause no harm and the capacitor can be readily replaced, but are inappropriate in the close confines of an IPG housing where the capacitor cannot be replaced and the electrolyte could harm other components. Therefore a need exists for an appropriate way to relieve gas pressure within the capacitor interior case chamber without loss of electrolyte.
Accordingly, the present invention is directed to the venting of gas from an flat electrolytic capacitor sealed within the hermetically sealed housing of an IMD, particularly an ICD. These problems are solved in accordance with the present invention by incorporating a gas vent and liquid electrolyte barrier into the electrolyte fill tube lumen that is used to fill the interior case chamber with electrolyte and then needs to be closed to prevent leakage of electrolyte.
Preferably, the fill port is formed through one of the case side wall and the cover wall for filling the capacitor with the liquid electrolyte upon welding of the cover to the side wall edge. The fill port is shaped to comprise a fill port tube having interior and exterior tube ends and a fill port ferrule intermediate the ends of the fill port tube and comprising a fill port ferrule flange extending transversely to and away from the fill port tube. The fill port ferrule is mounted in an opening disposed in one of the case wall and the cover wall with the ferrule flange in sealing engagement therewith to locate the exterior tube end extending outwardly away from the fill port ferrule flange and the interior tube end within the interior case chamber. Preferably the fill port tube and ferule are formed integrally of a the same material, wherein the fill port ferrule comprises a fill port flange extending radially outwardly transversely from the fill port tube.
A microporous plug is injected into and fills the fill port lumen, the plug formed of a microporous material allowing the escape of gas released from the liquid electrolyte during capacitor charging while preventing escape of liquid or vaporized electrolyte. Suitable plug materials include some silicones, polyimdes, polyphenylene oxides, cellulose acetates and triacetates and polysulfones. Several potting materials, such as epoxy or silicone rubber cement have the foregoing chemical resistance and hydrogen permeability properties and thus are suitable for use in the present invention.
The microporous plug is injected in liquid state into the tube lumen from the exterior tube end and preferably extends through the tube lumen and into the interior case chamber in a region substantialy covering the interior tube end such that when the plug solidifies, it adheres thereto with sufficient force to inhibit expulsion of the plug outward from the tube lumen under gas pressure.
Those of ordinary skill in the art will understand immediately upon referring to the drawings, detailed description of the preferred embodiments and claims hereof that many objects, features and advantages of the capacitors and methods of the present invention will find application in the fields other than the field of IMDs.

Implantable medical device having flat electrolytic capacitor with porous gas vent within electrolyte fill tube


In methods for simulating the evolution of a real-world quantum system over time, a state-preparation sequence of quantum gates is applied to a qubit register of a quantum computer. The state-preparation sequence is configured to prepare in the qubit register an initial model state representing an initial state of the real-world quantum system. A Hamiltonian operator for the real-world quantum system is received and used in the example method. The Hamiltonian operator represents two-body potential-energy interactions in a factorized form comprising at least one Majorana operator. A time-evolution-operator sequence of quantum gates comprising a block-encoded form of the Hamiltonian operator is now applied to the qubit register of the quantum computer, yielding a changed model state that represents a time-evolved state of the real-world quantum system. A measurement operation is applied subsequently to the qubit register. The measurement operation is configured to reveal an observable property of the changed model state.

Nature comprises an infinitude of quantum systems ranging from materials and biological structures to molecules, atoms, and atomic nuclei. Other quantum systems are products of molecular, nano- and bio-molecular engineering. Accordingly, in the varied disciplines of chemistry, biochemistry, physics, and materials science, accurate modeling of quantum systems is a shared objective. A reliable model of a quantum system is one that can be used to predict, outside of the laboratory, the results of experiments to interrogate the quantum system. Model-based predictions can be used, therefore, to validate or refute a theory or to guide experimental work to systems with desirable properties.
Drugs are examples of quantum systems for which reliable modeling is desired. A typical drug is a molecule comprising perhaps dozens of atomic nuclei and hundreds of electrons. The efficacy of a drug may depend on its ability to bind to a particular receptor in a host organism, which is a function of the configuration of the atomic nuclei and of the distribution of the electrons in the ground state of the molecule. In principle, these properties can be predicted based on the ground-state solution V) to the eigenvalue equationHψ=Eψ),  (1)where H is the Hamiltonian operator for the system of electrons and atomic nuclei, and E is the ground-state energy of the molecule.
For some molecular systems, an approximate solution to eq 1 can be obtained conventionally, using a state-of-the-art digital computer. However, the computing effort required to solve eq 1 is quite high and increases steeply with the number of valence electrons in the molecule. Accordingly, a common practice in state-of-the-art molecular modeling is to apply increasingly aggressive approximations to the Hamiltonian as the number of valence electrons increases. However, a less accurate Hamiltonian may fail to reflect important features of the quantum system, such that the solution obtained from eq 1 fails to predict the true ground-state properties.
Similar computational inefficiency is observed in scenarios in which the goal is to simulate the evolution of a quantum system over time, from one state to another. That approach may be used, for example, to map the reaction-coordinate surface of a chemical reaction, examine reaction intermediates and kinetics, etc., or to predict how a quantum system will respond to an externally applied perturbation. In general, the evolution of a quantum system is governed by eq 2,
                                          i                        ℏ                                                      d                                ψ                                            d                                t                                              =                      H                        ψ                          ,                            (        2        )
which, provided that H is independent of time, is solved by separation of variables, the general solution being a linear combination of the solutions of eq 1, each scaled by a time- and energy-dependent phase factor. Accordingly, the ability to work with an accurate Hamiltonian is important in these scenarios as well.
By inference, some of the difficulties of quantum simulation on conventional digital computers can be addressed via the fundamentally different architecture of a quantum computer. A quantum computer is a physical machine configured to execute logical operations based on or influenced by quantum-mechanical phenomena. Such logical operations may include, for example, mathematical computation. Current interest in quantum-computer technology is motivated by analysis suggesting that the computational efficiency of an appropriately configured quantum computer may surpass that of any practicable non-quantum computer when applied to certain types of problems. In addition to computer modeling of quantum systems, such problems also include integer factorization, data searching, and function optimization as applied to systems of linear equations and machine learning. Moreover, it has been predicted that continued miniaturization of conventional computer logic structures will ultimately lead to the development of nanoscale logic components that exhibit quantum effects, and must therefore be addressed according to quantum-computing principles.

Optimized block encoding of low-rank fermion Hamiltonians


Apparatus for securing a cap of a container to an external structure includes retaining structure configured to fit inside and engage the cap when the apparatus is installed. Securing structure connected to the retaining structure is used to releasably secure the cap to the external structure. In one embodiment, the retaining structure is a coil sized to exert a spring tension against the interior of the cap. In another embodiment, the retaining structure is an eyelet sized to receive a fastener secured within the cap. The securing structure may be comprised of a hook. Alternatively, the securing structure may be comprised of a clip or other closure mechanism. The apparatus may further include an intermediate bend providing a space that accommodates a feature of the cap, such as a vent in a fuel tank cap. The apparatus may remain in the cap when the cap is replaced on the container.

Containers are constructed to hold a variety of liquid and solid materials. Containers typically include one or more caps that, when removed from the container, are not attached to the container but are set aside, particularly when material is being added to or taken from the container. When the cap is set aside, it can become damaged, contaminated, lost, or forgotten. This problem is especially apparent with motor driven vehicles (e.g., motorcycles, automobiles, etc.) that have a fuel tank with a cap.
When a fuel tank cap, or gas cap, is temporarily removed, the operator of the motor vehicle typically does not have an adequate place to store the cap. Some vehicle owners place the cap on the vehicle, such as on the seat of the motorcycle or on the trunk of the car, where the cap can fall off and be damaged. Placing a gas cap on the vehicle may also damage the vehicle itself, including the paint on the vehicle. Other vehicle owners put the gas cap in their pocket, but that is not desirable given the gasoline residue on the cap. Some vehicle owners put the gas cap on top of the fuel pump, but again, the gas cap may fall off and be damaged or become contaminated. The gas cap may also be forgotten and lost should the vehicle owner leave the filling station without replacing the gas cap. What is needed is an apparatus that secures a cap of a container, such as a fuel tank cap, to an external structure in a way that does not damage the external structure, but also minimizes circumstances where the cap can become damaged, contaminated, or lost. The present invention addresses this need and other shortcomings that are present in current container systems.


A system augments stylus keyboarding with shorthand gesturing. The system defines a shorthand symbol for each word according to its movement pattern on an optimized stylus keyboard. The system recognizes word patterns by identifying an input as a stroke, and then matching the stroke to a stored list of word patterns. The system then generates and displays the matched word to the user.

Text input constitutes one of the most frequent computer user tasks. The QWERTY keyboard has been accepted as the standard tool for text entry for desktop computing. However, the emergence of handheld and other forms of pervasive or mobile computing calls for alternative solutions. These devices have small screens and limited keypads, limiting the ability of the user to input text. Consequently, text input has been revived as a critical research topic in recent years. The two classes of solutions that have attracted the most attention are handwriting and stylus-based virtual keyboarding.
Handwriting is a rather "natural" and fluid mode of text entry due to users' prior experience. Various handwriting recognition systems have been used in commercial products. However, the fundamental weakness of handwriting as a text entry method is its limited speed. While adequate for entering names and phone numbers, handwriting is too limited for writing longer text.
Virtual keyboards tapped serially with a stylus are also available in commercial products. The keyboard provided on the screen is typically the familiar QWERTY layout. Stylus keyboarding requires intense visual attention at almost every key tap, preventing the user from focusing attention on text output. To improve movement efficiency, optimization of the stylus keyboard layout has been considered both by trial and error and algorithmically. Using a keyboard layout such as ATOMIK (Alphabetically Tuned and Optimized Mobile Interface Keyboard), text entry is relatively fast. Reference is made to S. Zhai, M. Hunter & B. A. Smith, "Performance Optimization of Virtual Keyboards, Human-Computer Interaction," Vol.17 (2, 3), 229–270, 2002.
The need for entering text on mobile devices has driven numerous inventions in text entry in recent years. The idea of optimizing gesture for speed is embodied in the Unistrokes alphabet. In the Unistrokes alphabet, every letter is written with a single stroke but the more frequent ones are assigned simpler strokes. If mastered, a user could potentially write faster in the Unistrokes alphabet than in the Roman alphabet. The fundamental limitation of the Unistrokes alphabet, however, is the nature of writing one letter at a time.
Quikwriting method uses continuous stylus movement on a radial layout to enter letters. Each character is entered by moving the stylus from the center of the radial layout to one of the eight outer zones, sometimes crossing to another zone, and returning to the center zone. The stylus trajectory determines which letter is selected. While it is possible to develop "iconic gestures" for common words like "the", such gestures are relatively complex due to the fact that the stylus has to return to the center after every letter. In this sense, the Quikwriting method is fundamentally a character entry method.
Cirrin (Circular Input) operates on letters laid out on a circle. The user draws a word by moving the stylus through the letters. Cirrin explicitly attempts to operate on a word level, with the pen being lifted up at the end of each word. Cirrin also attempts to optimize pen movement by arranging the most common letters closer to each other. However, Cirrin is neither location nor scale independent.
It is important to achieve at least partial scale and location independency for the ease and speed of text entry. If all the letters defining a word on the keyboard have to be precisely crossed, the time to trace these patterns cannot be expected to be any shorter than tapping. As an example, if it is desired to draw a line from key "r" to key "d" as part of the word "word", within a tunnel connecting the two keys, such a closed-loop drawing process would take more time and visual attention than tapping "d" after "r". The user must place the pen in the proper position before drawing the word and ensure that the movement of the pen from letter to letter falls within the allowed pen stroke boundaries.
It is also important to facilitate skill transfer from novice behavior to expert performance in text entry by designing similar movement patterns for both types of behavior. The idea of bridging novice and expert modes of use by common movement pattern is used in the "marking menu". Instead of having pull-down menus and shortcut keys, two distinct modes of operation for novice and expert users respectively, a marking menu uses the same directional gesture on a pie menu for both types of users. For a novice user whose action is slow and needs visual guidance, marking menu "reveals" itself by displaying the menu layout after a pre-set time delay. For an expert user whose action is fast, the marking menu system does not display visual guidance. Consequently, the user's actions become open loop marks. However, the marking menu is not used for text entry due to the limited number of items can be reliably used in each level of a pie menu (8 or at the most 12). Reference is made to G. Kurtenbach, and W. Buxton, "User Learning and Performance with Marking Menus," Proc. CHI. 1994, pages 258–264; and G. Kurtenbach, A. Sellen, and W. Buxton, "An Empirical Evaluation of Some Articulatory and Cognitive Aspects of "Marking Menus", "Human Computer Interaction, 1993, 8(1), pages 1–23.
A self-revealing menu approach, T-Cube, defines an alphabet set by cascaded pie menus that are similar to a marking menu. A novice user enters characters by following the visual guidance of menus, while an expert user could enter the individual characters by making menu gestures without visual display. A weakness of the T-Cube is that it works at alphabet level; consequently, text entry using T-cube is inherently slow.
Dasher, another approach using continuous gesture input, dynamically arranges letters in multiple columns. Based on preceding context, likely target letters appear closer to the user's cursor location. A letter is selected when it passes through the cursor; consequently, cursor movement is minimized. This minimization, however, is at the expense of visual attention. Because the letter arrangement constantly changes, Dasher demands user's visual attention to dynamically react to the changing layout.
One possibility for introducing gesture-based text entry would be the use of shorthand. Traditional shorthand systems are efficient, but hard to learn for the user and difficult to recognize by the computer. Shorthand has no duality; it cannot be used by experts and beginners alike. In addition, shorthand has no basis in a virtual keyboard, so the user cannot identify the required symbol from the keyboard. If the user forgets shorthand symbols, a separate table must be consulted to find the symbol.
What is therefore needed is a form of continuous gesture-based text input that requires minimal visual attention, and that is based on keyboard entry, wherein a system and method recognize word patterns based on a virtual keyboard layout. The need for such system and method has heretofore remained unsatisfied.

System and method for recognizing word patterns based on a virtual keyboard layout

International Business Machines Corporation


An electric vane pump includes a first cover plate having a substantially planar first pump surface and a second cover plate coupled to the first cover plate defining a substantially planar second pump surface spaced apart from and extending substantially parallel to the first pump surface. A plurality of permanent magnets are fixed to a rotor. A plurality of radially moveable vanes are fixed for rotation with the rotor. Each vane is positioned between the first and second pump surfaces and has a first end slidably engaging the center vane support. An electric motor stator is positioned between the first and second cover plates and circumscribes the rotor. A resilient member biases each of the vanes into engagement with the center vane support.

This section provides background information related to the present disclosure which is not necessarily prior art.
A number of electric pumps have been disclosed combining an electric motor and a vane pump. For example, U.S. Patent No. 6,499,964 describes an electric motor and a vane pump that are usable separately or in combination with one another. While this concept may provide the desired pumping function, redundancies exist, possibly negatively affecting the cost, size and weight of the fluid pump.
In addition, U.S. Pat. No. 4,407,641 describes an electrically driven vane pump. The rotor of the electric motor and the rotor of the vane pump are integrated with each other. However, the disclosed pump arrangement includes multiple casings and occupies a relatively large volume of space. Accordingly, a need in the art exists for an improved integrated electric vane oil pump.


A dual film image capture, electronic image capture camera is capable of electronic information editing after each substantially simultaneous film and electronic exposure, and it magnetically records the information adjacent each one of the exposed film frames after completed exposure of the entire film length.

The invention relates generally to the field of photography, and in particular to a hybrid film exposure, electronic exposure camera. More specifically, the invention relates to a dual film image capture, electronic image capture camera that is capable of electronic information editing after each substantially simultaneous film and electronic exposure, and that magnetically records the information adjacent each one of the exposed film frames after completed exposure of the entire film length.
Prior art U.S. Pat. No. 5,710,954 issued Jan. 20, 1998 discloses a camera for exposing latent images on successive frames of a filmstrip having magnetic recording capacity, in which an electronic image sensor forms an electronic image corresponding to the latent image on a most-recently exposed one of the film frames substantially simultaneously with exposure of the latent image on that exposed frame, a motor is actuated to incrementally advance the filmstrip forward to permit the each unexposed one of the film frames to be exposed and is actuated after the final available one of the film frames is exposed to rewind the exposed film length rearward, and a magnetic head magnetically records user-selected information on the filmstrip adjacent each exposed frame.
The cross-referenced application Ser. No. 09/491,633, entitled DUAL FILM EXPOSURE, ELECTRONIC EXPOSURE CAMERA WITH FILM REWRITE FUNCTION, discloses a camera for exposing latent images on successive frames of a filmstrip having magnetic recording capacity, including a control that actuates a motor following exposure of each film frame to advance the filmstrip forward one frame increment, and a magnetic head that magnetically records user-selected information on the filmstrip adjacent the most-recently exposed one of the film frames as the filmstrip is advanced forward. The control first actuates the motor to advance the filmstrip rearward one frame increment when it is desired to change the existing information magnetically recorded adjacent the most-recently exposed one of the film frames to some new information, and then actuates the motor to advance the filmstrip forward one frame increment for the magnetic head to magnetically record the new information adjacent the same frame in place of the existing information. Preferably, an electronic image sensor is connected to the control to form an electronic image corresponding to the latent image on the most-recently exposed one of the film frames, and a memory is connected to the control to store the electronic image corresponding to the latent image on the most-recently exposed one of the film frames and to store at least some of the magnetically recorded information for the same frame superimposed on the electronic image.
The cross-referenced application Ser. No. 09/492,055, entitled DUAL FILM EXPOSURE, ELECTRONIC EXPOSURE CAMERA WITH DELAY IN FILM REWIND AFTER FINAL EXPOSURE TO ALLOW FILM REWRITE, discloses a camera for exposing latent images on successive frames of a filmstrip having magnetic recording capacity, includes a memory that stores a count indicative of the film frames remaining to be exposed (including a count of xe2x80x9c0xe2x80x9d to indicate that the final frame was exposed), a magnetic head that magnetically records user-selected information on the filmstrip adjacent each film frame, and a motor that is actuated following exposure of each film frame to advance the filmstrip forward one frame increment to permit the magnetic head to record the information on the filmstrip adjacent each exposed frame and that is actuated after the magnetic information is written on the filmstrip adjacent the final exposed frame to rewind the exposed film length rearward. An input receiving control is connected to the memory, the magnetic head, and the motor for delaying actuation of the motor to rewind the exposed film length rearward after the magnetic head has magnetically written the information on the filmstrip adjacent the final exposed frame, to give the user some time to manually input to the control that the information magnetically written adjacent the final exposed frame should be rewritten, and in the absence of the input by the time the delay has elapsed triggers actuation of the motor to rewind the exposed film length rearward.
The cross-referenced application Ser. No. 09/491,448, entitled DUAL FILM EXPOSURE, ELECTRONIC EXPOSURE CAMERA WITH MULTIPLE REWRITE ON FILM EXCEPT FOR FINAL EXPOSURE discloses a camera for exposing latent images on successive frames of a filmstrip having magnetic recording capacity, includes a memory that stores a count indicative of the film frames remaining to be exposed (including a count of xe2x80x9c0xe2x80x9d to indicate that the final frame was exposed), a magnetic head that magnetically records user-selected information on the filmstrip adjacent each film frame, and a motor that is actuated following exposure of each film frame to advance the filmstrip to permit the magnetic head to record the information on the filmstrip adjacent each exposed frame. A plurality of information selection switches can be manually used to select the information the magnetic head will magnetically record on the filmstrip adjacent the most-recently exposed one of the film frames including the final exposed frame. An input receiving control is connected to the memory, the magnetic head, the motor, and the information selection switches to actuate the motor to advance the filmstrip to permit the magnetic head to record the information on the filmstrip adjacent the most-recently exposed one of the film frames except the final exposed frame, each time at least one of the selection switches is used to select the information, and to record the information on the filmstrip adjacent the final exposed frame, only one time at least one of the selection switches is used to select the information.
A camera for exposing latent images on successive frames of a filmstrip having magnetic recording capacity, in which an electronic image sensor forms an electronic image corresponding to the latent image on a most-recently exposed one of the film frames substantially simultaneously with exposure of the latent image on that exposed frame, a motor is actuated to incrementally advance the filmstrip forward to permit the each unexposed one of the film frames to be exposed and is actuated after the final available one of the film frames is exposed to rewind the exposed film length rearward, and a magnetic head magnetically records user-selected information on the filmstrip adjacent each exposed frame, is characterized in that:
a memory stores the electronic image and the information to be magnetically recorded for every one of the exposed frames;
a display can show the electronic image and at least some of the information stored in the memory for any one of the exposed frames;
an exposed frame selector can be manually used to change the electronic image and the information shown in the display for any one of the exposed frames to the electronic image and the information stored in the memory for another one of the exposed frames; and
a plurality of information selectors can be manually used to change the information stored in the memory for the particular one of the exposed frames that corresponds to the electronic image shown in the display, whereby the information to be magnetically recorded adjacent any one of the exposed frames can be changed before the exposed film length is rewound rearward.
Preferably, a control is connected to the motor, the memory and the magnetic head to first actuate the motor after the final available one of the film frames is exposed to rewind the exposed film length rearward, then actuate the motor to continuously advance the exposed film length forward, and finally actuate the motor to rewind the exposed film length rearward. The control causes the magnetic head to magnetically record the information stored in the memory for each exposed frame on the exposed film length when the exposed film length is continuously advanced forward.

Dual film exposure, electronic exposure camera with electronic information editing after each exposure and information recording on film after completed exposure


Exemplary embodiments described herein are directed to conveyor belt tracking mechanisms with a single adjusting element and to conveyors having conveyor belts whose tracking may be adjusted in both directions using such conveyor belt tracking mechanisms. One exemplary conveyor belt tracking mechanism embodiment employs a pulley support yoke coupled to a specialized angular linkage having a linkage flexure pivot that translates linear motion into angular motion.

Conveyors are well known devices and come in many forms. Generally speaking, most common conveyors typically feature a conveyor body (frame), spaced apart pulleys, a conveyor belt that is stretched between the pulleys, and a conveyor belt tracking mechanism for adjusting both belt tension and the tracking of the moving conveyor belt. The tracking of a conveyor belt on the conveyor pulleys may depend largely on how squarely the belt is cut by the belt manufacturer. However, without a tracking mechanism, a conveyor belt will typically track to the left or to the right over time, and will frequently rub against the conveyor body. This rubbing often leads to conveyor noise, conveyor belt wear, and eventually to conveyor belt failure through mechanical abrasion.
Like conveyors themselves, conveyor belt tracking mechanisms are well known in the conveyor industry. While known conveyor belt tracking mechanisms may vary somewhat in design, such mechanisms typically include a tensioning screw located along each side of the conveyor body in the area of an adjustable conveyor drive pulley (see FIG. 1). The drive pulley commonly features at least a slightly trapezoidal or circular crown (profile) to facilitate movement of the conveyor belt along the pulley surface when appropriate.
As best illustrated in FIGS. 2A-2B, turning one of the adjusting screws shown in FIG. 1 results in a canting of the drive pulley with respect to the conveyor frame and the other pulley, and will cause greater tension along one side of the belt. As can be understood from observation of FIGS. 2A-2B, the conveyor belt will move away from the end of the pulley that is placing the belt under the most tension (i.e., the belt moves downward with respect to the drawing page in FIG. 2A and upward with respect to the drawing page in FIG. 2B). Hence, a manipulation of the adjusting screws may be employed to move the belt from one side of the conveyor to the other.
One negative effect of conveyor belt tracking mechanisms that utilize two screws for belt tracking adjustment is that both screws must normally be manipulated to achieve acceptable tracking of the conveyor belt. This operation can be tedious particular but not only because the tracking sensitivity of the belt is often quite high, meaning that even a minute rotation (e.g., ⅛ of one turn, depending on the tread pitch of the screw) of one of the tracking adjustment screws in one direction or the other will lead to the belt shifting away from the centerline of the conveyor.
Also, an unintended consequence of a conveyor belt tracking mechanism like that depicted in FIGS. 1 and 2A-2B is that the use of two adjusting screws during a belt tracking adjustment process often leads to an over-tensioning of the conveyor belt, which may result in an overloading of the pulley bearings and early bearing failure. Such over-tensioning of the conveyor belt is most often associated with conveyor belts comprised of a polyester carcass because the polyester material significantly restricts stretching of the conveyor belt. The benefit of such a conveyor belt is that through increased belt tension, it is possible to prevent the belt from slipping on the drive pulley when a heavy load is carried by the conveyor.
Not all conveyors employ polyester carcass conveyor belts. For example, polyester carcass conveyor belts are prohibited from use in food applications because an accumulation of food debris may remain in the carcass even after a sanitary wash down, and such an accumulation of food debris may lead to food contamination. Consequently, conveyor manufacturers often utilize closed cell stretch belts in food applications. Conveyor belts of such a construction have the benefit of not absorbing food debris or fluids and can be sanitized on the conveyor or removed from the conveyor and sanitized in a separate and typically chlorine-based cleaning solution before being placed back onto the also cleaned conveyor body.
In the case of a conveyor having a closed cell stretch conveyor belt, belt tension on the pulleys is defined by a stretch factor specified by the belt manufacturer. Because of the more stretchable nature of such a conveyor belt, placing additional tension on the belt will not produce a significant tracking improvement because the stretched belt will only add marginal additional tension to the conveyor drive system. Furthermore stretching the conveyor belt to achieve better belt tracking may lead to an increase in the physical length of the conveyor, which may ultimately result in an interference with other conveyors adjacent to the conveyor whose belt has been stretched. Therefore, rather than achieving increased belt traction through belt stretching, increased belt traction on the drive pulley of such a conveyor is more often produced by placing easy to clean grooves over the length of the pulley surface. The grooves act to provide additional traction between the belt and the pulley while still permitting the pulley to be cleaned in a sanitary manner.
In sanitary applications, such as food applications, the use of conveyor belt tracking mechanism adjusting screws with exposed threads is also unacceptable because of the difficulty associated with cleaning out the threads of the screws during conveyor sanitation. Consequently, there is an interest in altogether eliminating conveyor belt tracking mechanism adjusting screws.
An alternative conveyor design having this goal in mind is schematically represented in FIG. 3. In the conveyor of FIG. 3 both the drive and idler pulleys of the conveyor are crowned, with the intent being to keep the conveyor belt from tracking away from the center of the pulleys and conveyor body. A downside to this design, however, is that the conveyor belt will tend to be pushed by both pulleys towards the center of the conveyor, which ultimately leads to a crease in the belt and to early belt failure. Furthermore, the variability of the belt splicing process employed during conveyor belt manufacturing frequently results in an improper tracking of the belt on the conveyor if no other tracking adjustment is provided.
It can be understood from the foregoing background description that there is a need for a conveyor belt tracking mechanism that overcomes the deficiencies of known tracking mechanisms, and for a conveyor employing such a conveyor belt tracking mechanism. Therefore, an objective of the exemplary conveyor belt tracking mechanism embodiments described herein is to overcome the deficiencies of known tracking mechanisms.

Conveyor belt tracking mechanism and conveyor employing the same