A semiconductor memory device includes a plurality of address input blocks configured to respectively receive a plurality of addresses that are related to burst ordering and a control circuit configured to selectively disable all or a part of the address input blocks in response to a burst length information during a write operation mode.

1. Field
Exemplary embodiments of the present invention relate to a semiconductor designing technology, and more particularly, to a semiconductor memory device and a method for driving the semiconductor memory device.
2. Description of the Related Art
In general, a semiconductor memory device such as a Dynamic Random Access Memory (DRAM) device includes a buffer for transforming an external input signal, e.g., a signal of a Transistor-Transistor Logic (TTL) level, into an internal signal of the semiconductor memory device, e.g., a signal of a CMOS level. The buffer includes a command buffer for buffering an external command and outputting an internal command and an address buffer for buffering an external address and outputting an internal address.
FIG. 1 is a block view illustrating a conventional semiconductor memory device.
Referring to FIG. 1, the conventional semiconductor memory device includes a plurality of address buffers BUF1 and BUF2 for buffering a plurality of addresses A<18:0> that are inputted from the outside and outputting a plurality of internal addresses PA<18:0>, and a command buffer BUF3 for buffering an external command CMDB and outputting an internal command PCMD. Here, two address buffers BUF1 and BUF2 are illustrated for illustration purposes, but the address buffers BUF1 and BUF2 are provided corresponding to the addresses A<18:0> one-to-one.
Meanwhile, the address buffers BUF1 and BUF2 and the command buffer BUF3 maintain an enabled state in response to an enable signal BUFEN regardless of a read/write operation mode.
Here, the conventional semiconductor memory device having the above-described structure has the following features.
FIG. 2 shows a table describing Burst Ordering Specification according to a read/write operation mode.
Referring to FIG. 2, the 0th, first and second addresses A<0:2> are received and used during a read operation mode to perform a burst ordering control regardless of a burst length. On the other hand, when a burst length is 4 during a write operation mode, the second address A<2> is received and used among the 0th, first and second addresses A<0:2>.
FIG. 3 shows a timing diagram of a conventional semiconductor memory device in a write operation mode.
Referring to FIG. 3, it may be seen that a data is inputted through a data pad DQ after a write command WT is inputted and a CAS Write Latency (CWL) passes. Here, since the enable signal BUFEN maintains the enabled state in a logic high level continuously, all the address buffers BUF1 and BUF2 maintain the enabled state.
Therefore, the conventional semiconductor memory device incurs excessive power consumption because the address buffer BUF1 or BUF2 for receiving a particular address A<0:1> or A<0:2> is enabled all the time, although the conventional semiconductor memory device does not use the particular address A<0:1> or A<0:2> during a write operation mode.

Semiconductor memory device and method for driving the same


A charging balancing system and method thereof based on a battery operating process and are disclosed. This is done by detecting a state of all cells in a detecting battery assembly to generate detection parameters, analyzing the detection parameters to produce an operating process, selecting at least one of residual power estimation methods according to the operating process, so as to calculate a residual power of each cell, and adjusting the charging current and charging time for each cell according to the residual power. As such, the efficiency of charging balancing is promoted.

1. Field of Invention
The present invention is related to a battery charging balancing system and a method thereof. Particularly, the present invention is related to a battery charging balancing system and a method thereof based on a battery operation process thereof by selecting a state of charge (SOC) estimation method according to the battery operation process.
2. Related Art
Recently, as prevalence and vigorous development of mobile devices, it has been very common to use battery charging balancing technique for increasing lifetime of a secondary battery. Hence, it is quite an issue to promote the battery charging balancing efficiency for the relevant product fields.
Generally, the charging balancing technique includes two main parts, i.e. active balancing and passive balancing. To effectively promote the charging balancing efficiency, it is a general measure to estimate a residual amount of the cell as a reference for charging balancing control. Hence, the charging balancing efficiency is greatly affected by the SOC of the battery. If the SOC of the battery cannot be accurately estimated, the cells in the battery assembly may not be effectively subject to the charging balancing, results in an overly charging issue of the cells due to the poor charging efficiency. This may even causes a reduction of the lifetime of the secondary battery.
In view of this, some factories have proposed ways to estimate the SOC for various batteries, such as the open circuit voltage method, ampere-hour method, Coulomb counting method, Carmen wave filtering method. There are even some methods proposed to improve the above methods for more accurate estimation, such as the improved Coulomb counting method derived from the Coulomb counting method. However, the estimation methods previously applied on such secondary battery might not be still suitable to the battery after various operations process. For example, after a long use of the secondary battery, the ampere-hour method for estimation of the SOC may get distorted with the use time of the battery. Therefore, the SOC estimation methods and the improved versions thereof still have the issue of poor charging balancing caused from the inaccurate estimation of the SOC, and need to be well addressed.
In view of the above, there is a need to overcome the long existing issue of poor charging balancing caused from the inaccurate estimation of the SOC, by setting forth an effective technique.

Charging balancing system based on battery operating process and method thereof

Metal Industries Research & Development Centre


A method of authentication of a verifying device by a confirming device includes the confirming device receiving and storing a shared secret derived from at least a password of a user and sending a challenge. The method further includes the confirming device receiving a response to the challenge using the shared secret; determining if the response to the challenge is correct and if the response to the challenge is correct, authenticating the verifying device.

In a typical, conventional authentication system, a private key encrypts a message (the encrypted message is known as a digital signature) such that anyone having a public key (a published key) may decrypt the message. Digital signatures can be used to sign electronic documents and to ensure their integrity. That is, certificates may be provided, for example, by a login server (a trusted authority). These certificates which are digital signed by the login server provide security credentials for each user on the network. The security credentials are based on the requesting device and its user. The login server, generally knows the password of the user and issues the certificate to the device the user is logged into based on verification of the password of the user.

Authentication of a peer in a peer-to-peer network


In a process for the free radical-initiated aqueous emulsion polymerization for the preparation of an aqueous polymer dispersion, ethylenically unsaturated monomers are polymerized by means of a free radical polymerization initiator in the presence of organometallic compounds having a controlling effect.

The present invention relates to a process for free radical-initiated aqueous emulsion polymerization for the preparation of an aqueous polymer dispersion, in which at least one chemical compound (monomer) having at least one ethylenically unsaturated group is dispersed in an aqueous medium and polymerized by means of at least one free radical polymerization initiator in the presence of at least one organometallic compound.
Controlled polymerization reactions open up the possibility of synthesizing polymers having a specific molecular structure, defined molecular weight and low polydispersity and thus establishing a specific property profile of said polymers. In the last 40 years, a large number of methods which were essentially based on anionic and cationic mechanisms have been developed for this purpose (cf. O. W. Webster in Science 1991, 251, pages 887 to 893).
Compared with the ionic polymerization variants free radical polymerization reactions have the fundamental advantage that they can be carried out with a larger number of commercially important monomers and moreover can be effected by mass, solution, suspension and emulsion polymerization. However, attempts to find suitable catalysts for controlled free radical polymerization reactions have for a long time been unsuccessful.
It recently became known that N-oxyl radicals may be suitable for controlling free radical-initiated polymerization reactions of ethylenically unsaturated monomers. In this context, reference may be made, for example, to U.S. Pat. No. 4,581,429, EP-A 735 052, WO 94/11412, U.S. Pat. No. 5,322,912, U.S. Pat. No. 5,412,047 and GB 1 124 009.
The fact that organic metal complexes, too, are capable of controlling free radical polymerization processes is described by Wayland et al. in J. Am. Chem. Soc. 1994, 116, pages 7943 to 7944, for the controlled free radical solution polymerization of arylates using specific cobalt-porphyrin complexes, by way of example.
U.S. Pat. No. 5,312,871 discloses the use of a catalyst system for the controlled polymerization of ethylenically unsaturated monomers, consisting of an alkyl- or aryl-metal compound, an organic ligand and a stable radical. EP-A 841 346 discloses specific cobalt, rhodium and iridium complexes for controlling free radical polymerization reactions of ethylenically unsaturated monomers.
Application WO 87/03605 discloses the preparation of oligomeric compounds. The oligomers are prepared by free radical polymerization of ethylenically unsaturated monomers using specific transition metal catalysts. The preparation of aqueous polymer dispersions by means of free radical-initiated aqueous emulsion polymerization is, however, not disclosed.
Research Disclosure, December 1998, 416, pages 1595 to 1604, describes the controlling effect of specific porphyrin-, phthalocyanine- and salen-iron complexes in the solution and mass polymerization of styrene. In addition to the azobisisobutyronitrile used as free radical initiator, substituted alkyl bromides are used as polymerization initiator. The porphyrin-, phthalocyanine- or salen-iron complexes are always present in less than the molar stoichiometric amount relative to the substituted alkyl bromide used as a free radical polymerization initiator. Free radical aqueous emulsion polymerizations are not included.
In a corresponding manner, EP-A 714 416 discloses the use of specific cobalt complexes with tetradentate nitrogen ligands for controlling free radical polymerization reactions both in solution and in emulsion. The free radical initiators used are, exclusively, substituted aliphatic azo compounds.
U.S. Pat. No. 5,763,548 likewise discloses a process for controlled free radical polymerization, in which the controlling effect of organometallic compounds is employed.
WO 98/50436 describes the controlling effect of specific cobalt-oxime/boron fluoride complexes in free radical-initiated aqueous emulsion polymerization. Characteristic of the disclosed process is that hydrophobic solvents, for example higher alkanes or fatty alcohols for taking up the cobalt complex, are required in addition to the monomers.
Makino et al. disclose, in Polymer Preprints Vol. 39, March 1998, 288 and 289 (Am. Chem. Soc.; Polymer Chemistry Division), a process for the controlled free radical aqueous emulsion polymerization of ethyl methacrylate. The polymerization initiator used is ethyl 2-bromoisobutanoate. Furthermore, the emulsion polymerization is carried out in the presence of a relatively water-soluble copper(I)-bispyridyl complex. The molar ratio of the polymerization initiator used to the water-soluble copper(I)-bispyridyl complex is 1:1. The dispersant used is sodium dodecyl sulfate.
According to Matyjaszewski et al., Macromolecules 1998, 31, 5951 to 5954, the results obtained by Makino et al. are unsatisfactory. This is because, on the one hand, the copper(I)-bispyridyl complex is said to have much too high a water solubility and in addition the combination Cu2+/SO42xe2x88x92 is said to be completely disadvantageous for a controlling effect. Matyjaszewski et al. therefore recommend using nonionic polyethylene glycol oleyl ethers as dispersants and water-insoluble copper(I)-dialkylbispyridyl complexes as organometallic compounds.
In view of the above prior art, it is an object of the present invention to provide a process for controlled free radical aqueous emulsion polymerization, in which organometallic compounds other than those in the processes of the prior art exercise the controlling effect and which, in particular in the presence of sodium dodecyl sulfate as a dispersant, results in satisfactory control and furthermore does not require the presence of a hydrophobic organic solvent and requires no special polymerization initiators.
We have found that this object is achieved by a process for free radical-initiated aqueous emulsion polymerization for the preparation of an aqueous polymer dispersion, in which at least one monomer having at least one ethylenically unsaturated group is dispersed in an aqueous medium and polymerized by means of at least one free radical polymerization initiator in the presence of at least one organometallic compound, wherein the at least one organometallic compound on the one hand has the following structural feature of the formula I,
where:
and, on the otherhand, is such that at 20xc2x0 C. and 1 bar (absolute) its solubility in acidic, basic and/or neutral water is greater than its solubility in styrene.
The procedure for a free radical-initiated aqueous emulsion polymerization of monomers having at least one ethylenically unsaturated group has often been described in the past and is therefore sufficiently well known to a person skilled in the art [cf. for example Encyclopedia of Polymer Science and Engineering, Vol. 8, page 659 et seq. (1987); D. C. Blackley, in High Polymer Latices, Vol. 1, page 35 et seq. (1966); H. Warson, The Applications of Synthetic Resin Emulsions, page 246 et seq., Chapter 5 (1972); D. Diederich, Chemie in unserer Zeit 24, page 135 to 142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and Dispersionen synthetischer Hochpolymerer, F. Hxc3x6lscher, Springer-Verlag, Berlin (1969)]. It is usually carried out by dispersing the at least one monomer, frequently in the presence of dispersants, in an aqueous medium and polymerizing it by means of a free radical polymerization initiator. The novel process differs from the procedure only in the additional presence of at least one organometallic compound which has the structural feature of formula I.
Monomers having at least one ethylenically unsaturated group which are suitable for the novel process include in particular monomers capable of free radical polymerization in a simple manner, for example ethylene, vinylaromatic monomers such as styrene, xcex1-methyl styrene, o-chlorostyrene or vinyltoluenes, esters of vinyl alcohol and monocarboxylic acids of 1 to 18 carbon atoms such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of xcex1,xcex2-monoethylenically unsaturated mono- and dicarboxylic acids, preferably of 3 to 6 carbon atoms, in particular acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols of in general 1 to 12, preferably 1 to 8, in particular 1 to 4, carbon atoms, in particular methyl, ethyl, n-butyl, isobutyl and 2-ethylhexyl acrylate and methacrylate, dimethyl maleate or di-n-butyl maleate, nitriles of xcex1,xcex2-monoethylenically unsaturated carboxylic acids, such as acrylonitrile, and conjugated C4-8-dienes, such as 1,3-butadiene and isoprene. Said monomers are as a rule the main monomers which usually together account for more than 50% by weight, based on the total amount of the monomers to be polymerized by the novel free radical aqueous emulsion polymerization process. As a rule, these monomers have only moderate to low solubility in water under standard conditions of temperature and pressure (25xc2x0 C., 1 bar).
Monomers which have higher water solubility under the abovementioned conditions are, for example, xcex1,xcex2-monoethylenically unsaturated mono- and dicarboxylic acids and their amides, e.g. acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, and further vinylsulfonic acid and its water-soluble salts and N-vinylpyrrolidone.
Usually, the abovementioned monomers are incorporated by polymerization only as modifying monomers in amounts of less than 50, as a rule from 0.5 to 20, preferably from 1 to 10%, by weight, based on the total amount of the monomers to be polymerized.
Monomers which usually increase the internal strength of the films of the aqueous polymer dispersions usually have at least one epoxy, hydroxyl, N-methylol or carbonyl group or at least two non-conjugated ethylenically unsaturated double bonds. Examples of these are N-alkylolamides of xcex1,xcex2-monoethylenically unsaturated carboxylic acids of 3 to 10 carbon atoms, among which N-methylolacrylamide and N-methylolmethacrylamide are very particularly preferred, and their esters with alkanols of 1 to 4 carbon atoms. Monomers having two vinyl radicals, monomers having two vinylidene radicals, and monomers having two alkenyl radicals are also suitable. The diesters of dihydric alcohols with xcex1,xcex2-monoethylenically unsaturated monocarboxylic acids are particularly advantageous, among which acrylic or methacrylic acids are preferred. Examples of such monomers having two nonconjugated ethylenically unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates, such as ethylene glycol diacrylate, 1,2-propylene glycol diacrylate, 1,3-propylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylates and ethylene glycol dimethacrylate, 1,2-propylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate and 1,4-butylene glycol dimethacrylates, and divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, methylenebisacrylamide, cyclopentadienyl acrylate or triallyl cyanurate. The C1-C8-hydroxyalkyl methacrylates and acrylates, such as n-hydroxyethyl, n-hydroxypropyl- or n-hydroxybutyl acrylate and methacrylate, and compounds such as diacetoneacrylamide and acetylacetoxyethyl acrylate and methacrylate, are also particularly important in this context. In the case of aqueous emulsion polymer dispersions produced exclusively by the free radical aqueous emulsion polymerization method, the abovementioned monomers are incorporated by polymerization generally in amounts from 0.5 to 10% by weight, based on the total amount of the monomers to be polymerized.
The molar ratio of the ethylenically unsaturated monomers used for the free radical novel aqueous emulsion polymerization to the at least one organometallic compound which contains the structural feature of the formula I is as a rule xe2x89xa71, usually xe2x89xa710, often xe2x89xa7100 and frequently xe2x89xa71000.
Suitable free radical polymerization initiators for the novel free radical aqueous emulsion polymerization are all those which are capable of initiating a free radical aqueous emulsion polymerization without deactivating the at least one organometallic compound which has the structural feature I. In principle, they may be both peroxides and azo compounds. Of course, redox initiator systems are also suitable. In order to carry out the free radical aqueous emulsion polymerization particularly efficiently from the point of view of the desired properties and with respect to high cost-efficiency, the use of aliphatic azo compounds, for example azobisisobutyronitrile, as free radical initiator is preferred. The amount of the free radical polymerization initiator used is preferably from 0.1 to 2% by weight, based on the total amount of the monomers to be polymerized.
The manner in which the free radical polymerization initiator is added to the polymerization vessel in the course of the novel free radical aqueous emulsion polymerization seems to be of minor importance. The polymerization initiator may be either initially introduced completely into the polymerization vessel or added continuously or stepwise at the rate of its consumption in the course of the free radical aqueous emulsion polymerization. Specifically, this depends, in a manner known per se to a person skilled in the art, inter alia on the chemical nature of the polymerization initiator, on the monomer system to be polymerized and on the polymerization temperature.
A direct consequence of the abovementioned fact is that the total range from 0 to 150xc2x0 C. is suitable as a reaction temperature for the novel free radical aqueous emulsion polymerization, and temperatures of from 70 to 120xc2x0 C., preferably from 80 to 100xc2x0 C., particularly preferably from  greater than 85 to 100xc2x0 C., are preferably used. The novel free radical aqueous emulsion polymerization can be carried out at less than, equal to or greater than 1 bar (absolute), so that the polymerization temperature may exceed 100xc2x0 C. and may be up to 150xc2x0 C. Preferably, readily volatile monomers, such as ethylene, butadiene or vinyl chloride, are polymerized under superatmospheric pressure. The pressure may be 1.2, 1.5, 2, 5, 10 or 15 bar or may assume even higher values. If emulsion polymerizations are carried out under reduced pressure, pressures of 950, frequently 900, often 850, mbar (absolute) are established. The free radical aqueous emulsion polymerization is advantageously carried out at 1 bar (absolute) under an inert gas atmosphere, for example under nitrogen or argon.
For the purposes of the invention, instead of or in addition to the abovementioned free radical polymerization initiators, at least one compound of the formula III can also advantageously be used as a free radical polymerization initiator:
where:
X is an element from the group consisting of xe2x80x94Cl, xe2x80x94Br, xe2x80x94I, xe2x80x94OR20, where R20 is C1- to C20-alkyl, in which up to one third of the H atoms may, independently of one another, be replaced by xe2x80x94Cl, xe2x80x94Br and xe2x80x94I, xe2x80x94SR21, xe2x80x94SeR21, xe2x80x94OC(xe2x95x90O)R21, xe2x80x94OP(xe2x95x90O)R21, xe2x80x94OP(xe2x95x90O) (OR21)2, xe2x80x94OP(xe2x95x90O)OR21, xe2x80x94ON(R21)2, xe2x80x94SC(xe2x95x90S)N(R21)2, xe2x80x94SC(xe2x95x90S)R21, where R21 is -aryl or C1- to C20-alkyl and, in the case of xe2x80x94ON(R21)2, the two groups R21 with the N atom carrying them may form a 5- or 6-membered heterocyclic ring, and
R17, R18, R19 independently of one another, are each xe2x80x94H, xe2x80x94Cl, xe2x80x94Br, xe2x80x94I, xe2x80x94CO2H, xe2x80x94CN, xe2x80x94CO2R21, C1- to C20-alkyl, which may be unsubstituted or substituted, C3- to C8-cycloalkyl, which may be unsubstituted or substituted, -aryl, which may be unsubstituted or substituted, -aralkyl, which may be unsubstituted or substituted, or heterocyclyl, which may be unsubstituted or substituted.
If the free radical polymerization initiators used are compounds of the formula III, compounds where X is xe2x80x94Cl, xe2x80x94Br and xe2x80x94I are preferred.
The molar ratio of the at least one organometallic compound which contains the structural feature of the formula I to the at least one free radical polymerization initiator is dependent on, inter alia, the ethylenically unsaturated monomers which are used for the aqueous emulsion polymerization, on the size and the geometry of the reaction container and on whether a portion or the total amount of the ethylenically unsaturated monomers is initially taken in the aqueous reaction medium and the remaining amount is fed continuously or batchwise to the aqueous emulsion medium at the rate of consumption, on which free radical polymerization initiator and which organometallic compound which contains the structural feature of formula I are used or on whether a portion or the total amount of the at least one organometallic compound is initially taken in the aqueous reaction medium and the remaining amount is fed in continuously or batchwise in the course of the polymerization. An advantageous molar ratio of the at least one organometallic compound which contains the structural feature of the formula I to the at least one free radical polymerization initiator can be rapidly determined by a person skilled in the art for the respective system in preliminary experiments which are easy to carry out. It is usually from 0.00001:1 to 10:1, frequently from 0.001:1 to 1:1, often from 0.05:1 to 0.5:1. If exclusively free radical polymerization initiators of the formula III are used, the at least one organometallic compound which contains the structural feature of the formula I can be used for the free radical aqueous emulsion polymerization in less than the molar stoichiometric amount.
Usually, dispersants which keep both the monomer droplets and polymer particles dispersed in the aqueous phase and thus ensure the stability of the aqueous polymer dispersion produced are present during the novel free radical aqueous emulsion polymerization. Suitable dispersants of this type are both the protective colloids usually used for carrying out free radical aqueous emulsion polymerizations and emulsifiers.
Suitable protective colloids are, for example, polyvinyl alcohols, cellulose derivatives or vinylpyrrolidone-containing copolymers. A detailed description of further suitable protective colloids is to be found in Houben-Weyl, Methoden der organischen Chemie, Volume XIV/1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, 1961, pages 411 to 420. Of course, mixtures of emulsifiers and/or protective colloids can also be used. Preferably used dispersants are exclusively emulsifiers whose relative molecular weights, in contrast to the protective colloids, are usually less than 1000. They may be anionic, cationic or nonionic. Where mixtures of surfactants are used, the initial components must of course be compatible with one another, which can be checked by means of a few preliminary experiments in case of doubt. In general, anionic emulsifiers are compatible with one another and with nonionic emulsifiers. The same also applies to cationic emulsifiers, whereas anionic and cationic emulsifiers are generally incompatible with one another. Conventional emulsifiers are, for example, ethoxylated mono-, di- and trialkylphenols (degree of ethoxylation: from 3 to 50, alkyl radical: C4 to C12), ethoxylated fatty alcohols (degree of ethoxylation: from 3 to 50; alkyl radical: C8 to C36) and alkali metal and ammonium salts of alkyl sulfates (alkyl radical: C8 to C12), of sulfuric monoesters of ethoxylated alkanols (degree of ethoxylation: from 4 to 30, alkyl radical: C12 to C18) and ethoxylated alkyl phenols (degree of ethoxylation: from 3 to 50, alkyl radical: C4 to C12), of alkylsulfonic acids (alkyl radical: C12 to C18) and of alkylarylsulfonic acids (alkyl radical: C9 to C18). Further suitable emulsifiers are to be found in Houben-Weyl, Methoden der organischen Chemie, Volume XIV/1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, 1961, pages 192 to 208.
Furthermore, compounds of the formula IV
where R22 and R23 are each H or C4- to C24-alkyl and are not simultaneously H, and A and B may be alkali metal ions and/or ammonium ions, have proven to be surfactants. In the formula IV, R22 and R23 are preferably linear or branched alkyl of 6 to 18, in particular 6, 12 or 16, carbon atoms or xe2x80x94H, R22 and R23 not both being H simultaneously. A and B are preferably sodium, potassium or ammonium, sodium being particularly preferred. Compounds IV in which A and B are sodium, R22 is a branched alkyl radical of 12 carbon atoms and R23 is H or R22 are particularly advantageous Frequently, industrial mixtures which contain from 50 to 90% by weight of monoalkylated product, for example Dowfax(copyright) 2A1 (trademark of Dow Chemical Company) are used. The compounds IV are preferably used as dispersants in the novel process by themselves or, particularly preferably, as a mixture with ethoxylated fatty alcohols (degree of ethoxylation: from 3 to 50, alkyl radical: C8 to C36). The compounds IV are generally known, for example, from U.S. Pat. No. 4,269,749, and are commercially available. As a rule, the amount of dispersant used is from 1 to 3% by weight, based on the monomers to be subjected to free radical polymerization.
Of course, the abovementioned dispersants are suitable very generally for carrying out the novel process. However, the novel process also comprises the preparation of aqueous polymer dispersions of self-emulsifying polymers, in which monomers which have ionic groups give rise to stabilization owing to repulsion of charges of the same sign.
Anionic dispersants are preferably used for the novel process.
In the free radical aqueous emulsion polymerization process according to the invention, the controlling effect is achieved in the free radical aqueous emulsion polymerization by polymerizing the monomers in the presence of at least one organometallic compound which contains the structural feature shown in the formula I. A good controlling effect of the at least one organometallic compound is evident from the fact that, as the degree of polymerization progresses, the number average molecular weight (Mn) of the polymer formed from the at least one monomer having at least one ethylenically unsaturated group increases linearly with the monomer conversion (C) and the straight line shown in the graph, formed from Mn (ordinate) and a given C (abscissa), passes through the origin (Mn and C equal 0) and the polymer formed moreover has a low polydispersity, calculated from the quotient of weight average molecular weight (Mw) and Mn.
Compounds of the formula II
where:
R1, R2, R3, R4 independently of one another, are each xe2x80x94H, xe2x80x94CO2M1, where M1 is xe2x80x94H, an alkali metal, ammonium or (CH2CH2Oxe2x80x94)mM2, where M2 is xe2x80x94H, an alkali metal or ammonium and m is from 1 to 1000, xe2x80x94PO3HM1, xe2x80x94PO3M3M4, where M3 and M4 independently of one another are each an alkali metal, ammonium, C1- to C12-alkyl or substituted alkyl, in which up to four H atoms of the alkyl radical are replaced by xe2x80x94OM1, xe2x80x94SM1,xe2x80x94CO2M1, xe2x80x94NH2, a quaternized nitrogen atom, xe2x80x94SO3M1 and/or xe2x80x94OSO3M1 or xe2x80x94CH2Oxe2x80x94(CH2CH2Oxe2x80x94)mM2 and moreover
R1 and/or R3 independently of R2 and R4, may be xe2x80x94CN, and
R2 and R4, together with the carbon atoms carrying them and directly linked by a covalent bond, independently of R1 and R3, can form an aliphatically saturated, an aliphatically partly unsaturated or an aromatically unsaturated ring which can additionally contain from 1 to 3 hetero atoms, selected from the group consisting of N, O, S and P, the number of ring atoms being from 5 to 10, and
R5, R6, R7, R8 independently of one another are each xe2x80x94H, xe2x80x94F, xe2x80x94Cl, xe2x80x94Br, xe2x80x94I, xe2x80x94NO2, xe2x80x94CHO, xe2x80x94SM1, xe2x80x94OM1, xe2x80x94SO3M1, xe2x80x94CO2M1, xe2x80x94CN, xe2x80x94SCN, xe2x80x94PO3HM1, xe2x80x94PO3M3M4, xe2x80x94OSO3M1, xe2x80x94OPO3HM1, xe2x80x94OPO3M3M4, xe2x80x94NR10R11, where R10 and R11, independently of one another, are each xe2x80x94H or C1- to C6-alkyl, xe2x80x94SiR12R13R14, where R12, R13 and R14, independently of one another, are each C1- to C6-alkyl or C1- to C6-alkoxy, xe2x80x94OR15, xe2x80x94SR15, xe2x80x94CO2R15, xe2x80x94PO3HR15, xe2x80x94PO3R15R16, where R15 and R16, independently of one another, are each C1- to C3-alkyl or C2- to C6-alkyl, in which up to four H atoms of the alkyl radical are replaced by xe2x80x94OM1, xe2x80x94SM1, xe2x80x94CO2M1, xe2x80x94NH2, a quaternized nitrogen atom, xe2x80x94SO3M1 and/or xe2x80x94OSO3M1, xe2x80x94CH2Oxe2x80x94(CH2CH2Oxe2x80x94)mM2, C1- to C10-alkyl, in which at least half the carbon atoms are replaced by at least one substituent from the group consisting of xe2x80x94OM1, xe2x80x94SM1, xe2x80x94CO2M1, xe2x80x94NH2, a quaternized nitrogen atom, xe2x80x94SO3M1 and xe2x80x94OSO3M1, C2- to C10-alkenyl, in which up to three H atoms are replaced by xe2x80x94OM1, xe2x80x94SM1, xe2x80x94CO2M1, xe2x80x94NH2, a quaternized nitrogen atom, xe2x80x94SO3M1 and/or xe2x80x94OSO3M1, and moreover
two of the radicals R5, R6, R7 and R8, which are carried by neighboring carbon atoms, together with the carbon atoms carrying them and independently of the other radicals, can form an aliphatically saturated, an aliphatically partly unsaturated or an aromatically unsaturated ring which can additionally contain from 1 to 3 hetero atoms selected from the group consisting of N, O, S and P, the number of ring atoms being 5 or 6, and
the two radicals R7 and/or the two radicals R8, in each case with the carbon atoms carrying these radicals, can form a 5- or 6-atom covalent, bridging chain, the atoms bonded to the chain members not being included,
R9 is xe2x80x94H,
xe2x80x94.xe2x80x94.xe2x80x94 is either a covalent bond or a covalent, bridging chain of up to three atoms, the atoms bonded to the chain members not being included,
Me is a metal ion,
L is a Lewis base and
p is 0, 1 or 2.
are used as suitable one or more organometallic compounds containing the structural feature of the formula I.
Preferred organometallic compounds of the formula II are those in which the carbon atoms carrying R1 and R2 and R3 and R4 are bonded to one another directly by means of a covalent bond, and R1 to R4 are either H atoms or part of an unsubstituted or substituted benzene ring. Particularly preferred organometallic compounds of the formula II are those in which moreover at least one of the radicals R5 to R8 is OH. Especially preferred organometallic compounds of the formula II are those in which R7 is OH. In particular, preferred organometallic compounds of the formula II are those in which the carbon atoms carrying R1 and R2 and R3 and R4 are bonded to one another directly by means of a covalent bond, R1 to R4 are either H atoms or, with the carbon atoms carrying them, are part of a benzene ring, R7 is OH and R5, R6 and R8 are each H atoms. The organometallic compound in which R1 to R4 are each H atoms is referred to as a hydroxysalen complex. If, on the other hand, R1 to R4, with the carbon atoms carrying them, are part of a benzene ring, the organometallic compound is referred to as a hydroxysaloph complex. If in both cases R7 is likewise an H atom, the terms salen and saloph complexes, respectively, are used.
Me is preferably a metal ion which can occur reversibly in at least two oxidation states. Me is advantageously selected from the group consisting of Fe2+, Fe3+, Ru2+, Ru3+, Cr2+, Cr3+, Mo2+, Mo3+, W2+, W3+, Co2+, Co3+, Re2+, Re3+, V2+, V3+, Mn2+, Mn3+, Zr2+, Zr3+, Zr4+, Ti2+, Ti3+, Ti4+, Ce2+and Ce3+. Often, the metal ion is selected from the group consisting of Fe2+, Fe3+, Co2+, Co3+, Cr2+, and Cr3+. Frequently, the metal ion is used in the lower oxidation state.
Suitable Lewis bases L are, for example, water, tetrahydrofuran, dioxane, pyridine, ammonia, primary, secondary or tertiary aliphatic or aromatic amines, whose aliphatic or aromatic radicals may be substituted, and unsubstituted or substituted trialkyl-, trialkoxy-, triaryl- and triaryloxyphosphines. Depending on the metal ion Me, the radicals R1 to R8 and the conditions during the free radical aqueous emulsion polymerization, the number p of the co-ordinated Lewis bases L may be 0, 1 or 2.
The syntheses of the organometallic compounds of the formula II have often been described in the past and are therefore sufficiently well known to a person skilled in the art cf. in this context EP-A 362 139 and JP 1 090 150 and Yang et al. in Hecheng Huaxue 1995, 3(1), 75 et seq., Kasuaga et al. in Inorg. Chem. Acta 1989, 157, 267 et seq., Spiratos et al. in Rev. Roum. Chim. 1980, 25, 1083 et seq., Spiratos et al. in Rev. Roum. Chim. 1984, 29, 457 et seq., Fullerton and Ahern in Tetrahedron Lett. 1976, 139 et seq., Zelentsov and Somova in Zh. Obshch. Khim. 1974, 44(6), 1309 et seq., Vitalini et al. in Macromolecules 1996, 29, 4478 et seq., Gaber et al. in Egypt. J. Chem. 1992, 34, 107 et seq., Kanbayashi et al. in J. Chromatogr. 1987, 386, 191 et seq., Marcu et al. in Polym. Bull. 1986, 16(2-3), 103 et seq., Dorutiu et al. in Stud. Univ. Babes-Bolyai, [Ser.] Chem. 1980, 25(2), 49 et seq., Zelentsov and Somova in Zh. Neorg. Khim. 1973, 18(8) 2128 et seq. and Mukheriee and Ray in J. Indian Chem. Soc. (1955), 604, 606 and 607]. Usually, an aromatic hydroxycarbonyl compound of the formula V is reacted with a diamine of the formula VI according to the following reaction scheme to give a Schiff base reaction product of the formula VII, which in turn forms with the metal ion, virtually quantitatively, the organometallic compound of the formula II:
At 1 bar (absolute) and 20xc2x0 C., organometallic compounds of the formula II have a certain solubility in water an in organic solvents and in olefinically unsaturated monomers, of which styrene is a typical member. Their solubility in water can be significantly influenced by adding bases or acids. The use of organometallic compounds of the formula II whose solubility under the abovementioned conditions in 1000 g of acid, basic and/or neutral water is greater than their solubility in 1000 g of styrene is claimed according to the invention. In this publication, solubility is understood as meaning the maximum amount of dissolved organometallic compound of the formula II in grammes for 1000 g of solvent. UV/VIS spectroscopic methods are particularly suitable for determining the solubility of these organometallic compounds.
Organometallic compounds which are suitable according to the invention and contain the structural feature of the formula I have, as a rule, a solubility of xe2x89xa6100 g/1000 g, but often a solubility of xe2x89xa70.001 g/1000 g and frequently xe2x89xa70.1 g/1000 g in acidic, basic and/or neutral water at 1 bar (absolute) and 20xc2x0 C. In styrene, said organometallic compounds have, as a rule, a solubility of xe2x89xa61 g/1000 g, often xe2x89xa60.1 g/1000 g and frequently xe2x89xa60.01 g/1000 g under identical conditions.
The novel process can be carried out, for example, by initially taking either a portion or the total amount of the required water, of the required at least one organometallic compound containing the structural feature of the formula I, of the at least one polymerization initiator, of, if required, the at least one emulsifier, of, if required, the at least one protective colloid used and/or of the at least one monomer having at least one ethylenically unsaturated group and of, if required, the further conventional assistants and additives in a reaction container and heating the content of the reaction container to, the reaction temperature. At this temperature any remaining residual amounts of water, of the at least one organometallic compound containing the structural feature of the formula I, of the at least one polymerization initiator, of any emulsifier, of any protective colloid used and/or of the at least one monomer having at least ethylenically unsaturated group and of any further conventional assistants and additives are added continuously or batchwise while stirring and then, if required, still kept at the reaction temperature.
However, the novel process can also be carried out by initially taking a portion or the total amount of the required water, of, if required, the at least one emulsifier, of, if required, the at least one protective colloid used and/or of the at least one monomer having at least one ethylenically unsaturated group and of, if required, the further conventional assistants and additives and, if desired, a portion of the at least one organometallic compound containing the structural feature of the formula I and of the at least one polymerization initiator in a reaction container and heating the content of the reaction container to the reaction temperature. At this temperature, the total amount or any residual amount of the at least one organometallic compound containing the structural feature of the formula I and of the at least one polymerization initiator and any residual amounts of water, of any emulsifier, of any protective colloid used and/or of the at least one monomer having at least one ethylenically unsaturated group and of any further conventional assistants and additives are added continuously or batchwise while stirring and then, if required, still kept at the reaction temperature.
It is also possible initially to take a polymer seed in a portion or the total amount of the required water, of the at least one organometallic compound containing the structural feature of the formula I, of the at least one polymerization initiator, of, if required, the at least one emulsifier, of, if required, the at least one protective colloid used and/or of, if required, the further conventional assistants and additives at the reaction temperature in a reaction container. The total amount of the at least one monomer having at least one ethylenically unsaturated group and any residual amounts of water, of the at least one organometallic compound containing the structural feature of the formula I, of the at least one polymerization initiator, of any emulsifier, of any protective colloid used and/or of any further conventional assistants and additives are added continuously or batchwise, while stirring, to the reaction mixture present in the reaction container at the reaction temperature and then, if required, still kept at the reaction temperature.
In this seed procedure, it is also possible if required initially to take a portion of the at least one organometallic compound containing the structural feature of the formula I and of the at least one polymerization initiator in the reaction container as well and to add, at the reaction temperature, the total amount or the residual amount of the at least one organometallic compound containing the structural feature of the formula I and of the at least one polymerization initiator and the total amount of the at least one monomer having at least one ethylenically unsaturated group and any residual amounts of the water, of any emulsifier, of any protective colloid used and/or of any further conventional assistants and additives continuously or batchwise while stirring.
In the abovementioned procedures, however, it is also possible, in addition to or instead of the at least one organometallic compound containing the structural feature of the formula I, to use at least one organometallic compound of the formula VIII
where Z is aryl or C1- to C12-alkyl and L and p have the abovementioned meanings.
Organometallic compounds of the formula VIII differ from organometallic compounds of the formula II only in that the metal ion is additionally bonded to an alkyl or aryl group. The bond between the metal ion and the alkyl or aryl group is thermally labile. At temperatures as are usual in the novel free radical aqueous emulsion polymerization (typically from 70 to 120xc2x0 C.), the bond between the metal ion and the alkyl or aryl group is thermally cleaved and the organometallic compound of the formula II is formed in situ according to the following reaction scheme:
Organometallic compounds of the formula VIII are obtainable in a simple manner from the corresponding halides of the formula IX by reaction with a Grignard reagent or an alkyl- or aryllithium compound according to the following reaction scheme:
where Hal is xe2x80x94Cl, xe2x80x94Br or xe2x80x94I and Z is aryl or C1- to C12-alkyl and L and p have the abovementioned meanings.
An essential aspect according to the invention is that the novel process is advantageous for the preparation of aqueous dispersions of block polymers. This is possible in a simple manner by first polymerizing one type of monomer and then continuing the polymerization with another type of monomer. By further changes of monomer, it is also possible to produce polyblocks.
Of course, the residual monomers remaining in the aqueous polymer dispersion after the end of the main polymerization reaction can be removed by steam stripping and/or inert gas stripping and/or by chemical deodorization, as described, for example, in DE-A 4 419 518, EP-A 767 180 or DE-A 3 834 734, without the polymer properties of the aqueous polymer dispersion being adversely affected. It is also important that the novel organometallic compounds which have the structural feature of the formula I do not as a rule reduce the action of the microbicides which usually have to be added as preservatives to the aqueous polymer dispersions.
The at least one organometallic compound which has the structural feature of the formula I can, if required, likewise be removed from the aqueous polymer dispersion obtainable according to the invention. For example, this can be done by separating the disperse polymer from the aqueous serum by centrifuging, redispersing it by adding neutral, acidic and/or basic water, centrifuging it again, etc., the at least one organometallic compound accumulating in each case in the serum.
Alternatively, the at least one organometallic compound which has the structural feature of the formula I can be separated from the novel aqueous polymer dispersion also by coagulation and repeated washing of the coagulated polymer with neutral, acidic and/or basic water.
Aqueous polymer dispersions which contain at least one organometallic compound which has the structural feature of the formula I or which are prepared by the novel process described are very useful in particular for the preparation of adhesives, for example contact adhesives, building adhesives or industrial adhesives, binders, for example for paper coating, emulsion paints or printing inks and printing lakes for printing on plastics films, for the production of nonwovens and for the production of protective layers and water vapor barriers, for example, for priming.
General determination of the solubility of organometallic compounds of the formula II by UV/VIS spectroscopy.
At 20xc2x0 C. and 1 bar (absolute), the organometallic compound of the formula II was added, while stirring, to water which contained 0.5% by weight of sodium carbonate [Na2CO3] and to styrene in each case in an amount sufficient to saturate them with the organometallic compound. Undissolved organometallic compound was filtered off over a 0.2 xcexcm filter.
Moreover, under the abovementioned conditions, 4 calibration solutions each in water and in styrene, whose concentrations (grams of dissolved organometallic compound per 1000 g of water or styrene) were below the respective solubilities and were exactly known, were prepared with each organometallic compound investigated.
By means of UV/VIS absorption measurements of the solutions thus prepared using a UVIKON 922 spectrometer, the respective UV/VIS absorptions were measured and the respective solubilities were determined therefrom using the Beer-Lambert law.
For example, the solubilities of the following organometallic compounds of the formula II were determined:

Method for radical aqueous emulsion polymerization


A raster scan control system (18) for use with a charged-particle beam delivery system (20) provides precise control of large currents driving an inductive load. The beam delivery system includes a nozzle through which a charged-particle beam (24), such as a proton beam, passes prior to being directed to a target (32). The nozzle includes both fast and slow sweep scan electromagnets (204, 208) that cooperate to generate a sweeping magnetic field that steers the beam along a desired raster scan pattern at the target. The electromagnets are driven by large currents (213, 215) from the raster scan control system. The raster scan control system includes both fast and slow power amplifiers (212, 214) for delivering the desired large currents to the fast and slow electromagnets, respectively; monitoring means (206, 210) for monitoring the magnetic fields; sensing means (212, 230) for sensing the large currents; feedback means for maintaining the magnetic fields and large current at desired levels; out of tolerance means for automatically causing the servo power amplifiers to steer the beam away from the target area in the event the error signal becomes excessive; a programmable raster generator (80) for providing the fast and slow power amplifiers with a raster scan signal (216, 218) that defines the desired raster pattern; and a power supply (74) for delivering the requisite power to the power amplifiers and other components.

The present invention relates to a magnetic field control system. More particularly, the present invention relates to a control system for controlling the magnetic fields created by the electromagnets in the nozzle of a charged-particle beam delivery system for the purpose of steering the charged-particle beam to follow a desired raster scan pattern across a selected target site.
A beam delivery system typically includes a nozzle through which a charged-particle beam, such as a proton beam, passes on its way to a target area. The nozzle usually includes collimator devices for confining the beam to a desired area or shape on the target. It is known in the art to include an electromagnet(s) in the nozzle that, as controlled by a drive current, generates a magnetic field that interacts with the charged-particle beam so as to bend or deflect the beam in a desired direction(s). By applying a current of a known magnitude to the electromagnet(s) in the nozzle, a magnetic field of a predictable intensity is generated that bends or deflects the beam a predictable amount. The stronger the magnetic field, the more the charged-particle beam can be bent. Hence, by selectively applying a current of a controlled magnitude to the electromagnet(s), the beam can be steered to a desired point on the target area.
The strength of the magnetic field required to bend a charged-particle beam dictates that an electromagnet having a large number of ampere-turns be employed. A low number of turns provides low resistance and inductance, but dictates that a high current be used. Unfortunately, such high currents are difficult to generate and control, and further create heat dissipation problems. A high number of turns advantageously allows the current to be maintained at a manageable level, but unfortunately brings with it a high inductance and resistance. Disadvantageously, a high inductance limits the rate at which the current, and hence the magnetic field, can change. Thus, prior art uses of electromagnets to steer a charged-particle beam have typically been limited to static uses, that is, uses where the steering of the beam is not changing, or is changing at a very slow rate. However, what is needed for a beam delivery system where the target is larger than the beam diameter is a system for dynamically steering a charged-particle beam so that the beam can be scanned across the target in a desired manner.
It is known in the art to use two magnets in the nozzle of a beam delivery system, oriented so as to create orthogonal magnetic fields, and to apply a fixed magnitude voltage to the coil of one magnet in one direction for a prescribed period of time, and then to apply this fixed magnitude voltage to the same coil in the opposite direction for a prescribed period of time, with the rate of change of the current being limited by the inductance of the coil. In this manner, a sawtooth current waveform is passed through the magnet coil, resulting in a magnetic field that linearly changes from one peak value to an opposite peak value. The changing magnetic field causes the beam to bend or move across the target area from one edge to the other in a straight line. When a similar fixed magnitude voltage is applied to the other magnet coil, another magnetic field, substantially independent of the first magnetic field, causes the beam to bend or move across the target area in a direction that is orthogonal to the movement caused by the first magnetic field. The combined effect of both magnetic fields is to move the beam across the target area in a diagonal sweep pattern. Typically, one magnet sweeps the beam in one direction, e.g. a horizontal direction, at a much faster rate than the other magnet sweeps the beam in an orthogonal direction, e.g., a vertical direction. Hence, one magnet is referred to as the "fast magnet" and the other is referred to as the "slow magnet".
Unfortunately, such a diagonal sweep pattern, even when there is a large difference between the sweep rates of the fast and slow magnets, does not always efficiently or uniformly cover the target area, there being significant portions of the target area that are not covered by a diagonal sweep pattern. Further, because of the large current magnitudes involved in such an arrangement, there is no easy way to control the current, especially at high sweep rates, other than to change its direction through the coil by abruptly reversing the voltage applied to the coil. This type of abrupt switching, or "bang-bang" type of control, makes it difficult to accurately control that portion of the target area that is swept with the beam. Either the beam sweep is on, in which case the diagonal sweep pattern goes from one edge of the target area all the way over to the other, or the beam sweep is off, in which case the beam does not move within the target area. What is needed, therefore, is a means for selectively controlling the sweep pattern within the target area so that all or a selected portion of the target area can be efficiently and uniformly swept with a beam that is accurately controlled.

Raster scan control system for a charged-particle beam


An ophthalmological analysis instrument for measuring a topography of a surface of an eye includes a projection apparatus and a monitoring apparatus. The projection apparatus has at least one illumination device and an aperture device. The illumination device has a first light source. The aperture device images an image pattern on a surface of an eye. The monitoring apparatus has a camera and an objective lens, wherein images of the imaged image pattern being recordable by the monitoring apparatus, and a topography of the surface being derivable from the images. A magnification of the image can be varied by means of the objective lens.

In the analysis instruments and topography systems known from the prior art, an eye is generally illuminated with monochromatic light, such as infrared light for example, so as to avoid dazzling the person or subject to be examined where possible. Topography systems are thus known which, in addition to measuring a surface of an eye, also enable pupillometric measurements. In particular when the eye is illuminated with monochromatic light, which is only partly visible, a contraction of the pupil is effectively prevented, and therefore an illumination of this type is particularly well suited for pupillometric measurements. Topography systems may, however, also have a plurality of light colours for illumination of an eye. For example, Placido rings are then projected onto the eye in different monochromatic light colours. This is basically used for distinction of the rings of the image pattern imaged on the eye and for the sole purpose of determining a topography. Placido rings of this type in different monochromatic light colours consequently form the first light source alone. It is further known to examine meibomian glands under infrared light.
Analysis instruments for measuring topography or what are known as "keratometers" can also be used for non-invasive analysis of a tear film on an eye. The image pattern projected onto the surface of the eye is recorded substantially continuously, wherein any break-up in the tear film can be identified by a change to the image pattern. In order to establish the quality of the tear film, a break-up time thereof is generally measured. This measurement is likewise carried out by illuminating the eye with infrared light. For example, in addition to the topography of the surface of the eye, a measurement of a tear film is also of utmost importance when selecting contact lenses. Furthermore, analysis of a tear film is limited merely to a distribution of the tear film over the eye. A disadvantage of the known analysis instrument and method is that the possibilities for examining an eye are limited. It is therefore desirable to broaden the examination possibilities of an instrument of this type so as to obtain further and more detailed measurement results where necessary, which can be used for example for improved contact lens selection and fitting.
The object of the present invention is therefore to propose an ophthalmological analysis instrument and an analysis method which uses an ophthalmological analysis instrument, with which the examination possibilities of a topography system are broadened and improved.
This object is achieved in one embodiment of the invention by an apparatus having a projection apparatus including at least one illumination device and an aperture device, the illumination device having at least one first light source, the aperture device being capable of imaging an image pattern on a surface of an eye; and a monitoring apparatus having a camera and an objective lens said monitoring apparatus being capable of recording images of the imaged image pattern, wherein a topography of the surface of the eye being derivable from the images, and a magnification of the images can be varied by the objective lens. This object is also achieved in a second embodiment of the invention by a method including the steps of imaging an image pattern onto the surface of the eye using the aperture device; recording images of the imaged image pattern using the monitoring apparatus; and deriving a tear film flow from the images by measuring a speed of movement of particles situated on the surface of the eye.
The ophthalmological analysis instrument according to the invention, in particular for measuring a topography of a surface of an eye, has a projection apparatus and a monitoring apparatus, the projection apparatus comprising at least one illumination device and an aperture device, the illumination device having at least one first light source, it being possible to image an image pattern on a surface of an eye by means of the aperture device, the monitoring apparatus having a camera and an objective lens, images of the imaged image pattern being recordable by means of the monitoring apparatus, and a topography of the surface being derivable from the images, wherein a magnification of the image can be varied by means of the objective lens.
Since the monitoring apparatus has a camera and an objective lens, the images obtained are quality images which can be utilised effectively. It is thus possible, depending on the type of measurement, to select a magnification of the objective lens in such a way that the object to be measured or the property to be measured can be visually illustrated such that evaluation of the image and particularly accurate measurement results are generally made possible. In particular in the case of a very large magnification, it is possible to focus the tear film such that particles situated in the tear film are visible, for example dust particles or foreign bodies. Any movement of these particles can be tracked and measured with respect to direction of movement and speed. The direction in which and the speed at which the tear film flows can be derived from this. This measurement can be used to determine tear film quality more accurately.
To this end, the objective lens may have a magnification changer, by means of which at least one lens can be introduced into a beam path of the objective lens and removed therefrom. Compared to a variable magnification adjustment, which is likewise conceivable, a magnification changer can be produced particularly easily and cost effectively. It is also possible to always use constant, standardised magnifications for the various measurements, which simplifies considerably the measurements and an evaluation or analysis of the images.
At least three magnifications can advantageously be formed by means of the objective lens. A first, normal magnification can be used to measure the topography of the surface of the eye. A second, large magnification can be used to measure or analyse a tear film. For example, it is possible to focus on a lipid layer, in particular with shallow depth of field, so as to determine the thickness of said lipid layer. A third, small magnification can be used in particular for meibometric examination, since the recording of images of meibomian glands requires an enlarged spacing between the analysis instrument and the eye inter alia.
The first light source may also emit light in a predominantly monochromatic spectrum. The light of the first light source can thus be better identified by the monitoring apparatus.
The first light source may advantageously emit light in a predominantly infrared spectrum. Infrared light has a particularly low dazzling effect on the eye to be examined and is easily produced.
The illumination device may have at least one further light source, which can emit polychromatic light in a predominantly visible spectrum. In addition to the use of substantially monochromatic light or light of a relatively narrow wavelength range, the further light source may make it possible to illuminate the surface of the eye with polychromatic, visible light, whereby additional measurements of properties of the eye and attainment of more accurate measurement results are possible. Compared to monochromatic or infrared light, it is possible to determine a degree of reddening of the eye using polychromatic light. It is also possible to measure a thickness of a tear film or of a lipid layer of the tear film relatively accurately in a non-invasive manner, since coloured interference patterns of the lipid layer can be produced using polychromatic light and can be used for measurements of this type.
It is particularly advantageous if the further light source can emit predominantly white light. Particularly good colour reproduction can be achieved with white light, which considerably improves measurement accuracy, in particular when measuring the degree of reddening of the eye and when producing a coloured interference pattern.
In one embodiment, the further light source can be formed from a multiplicity of uniformly distributed light-emitting diodes. For example, the light-emitting diodes themselves may form the image pattern. The light-emitting diodes can thus be arranged in a ring or behind an aperture, which can project the image pattern onto the eye. The light-emitting diodes which form the further light source can be arranged on the illumination device together with light-emitting diodes which form the first light source. It is thus possible to operate the relevant light-emitting diodes separately or together, as required. A number of light-emitting diodes of the first light source to a number of light-emitting diodes of the further light source can be selected in a ratio of 1 to 3.
It is particularly advantageous if, for a beam path of the monitoring apparatus, an opening is formed in the aperture device in an instrument axis of the aperture device orientable in the direction of an optical axis of the eye. The surface of the eye can thus be illuminated on all sides with the image pattern by means of the aperture device. For example, the aperture device can thus be formed from an illuminating ring or a plurality of concentric rings of this type so as to produce a Placido image pattern. If the instrument axis of the aperture device is oriented toward the optical axis of the eye, the beam path of the monitoring apparatus can extend directly along the optical axis or thereover, so that the eye can be monitored from the front through the opening, thus considerably simplifying pupillometric measurements in particular.
The analysis instrument may thus also have a dazzling apparatus for exciting a dazzling stimulus onto the eye, the dazzling apparatus possibly having a dazzling light source and a beam splitter for reflecting the dazzling light source into the beam path of the monitoring apparatus. The eye can thus be dazzled by this dazzling apparatus, wherein a response of the eye can be recorded at the same time by means of the monitoring apparatus. For example, a movement of the pupil prompted by the dazzling can be recorded and evaluated. The dazzling apparatus can be operated independently of the illumination device and image patterns produced thereby.
It is further possible to utilise the illumination device and/or the dazzling apparatus for dazzling the eye with the objective of increasing production of tear fluid. The formation of a tear film can thus be examined and measured.
The analysis method according to the invention is carried out using an ophthalmological analysis instrument for measuring a topography of a surface of an eye, the analysis instrument comprising a projection apparatus and a monitoring apparatus, the projection apparatus comprising at least one illumination device and an aperture device, an image pattern being imaged onto the surface of the eye by means of the aperture device, images of the imaged image pattern being recorded by means of the monitoring device, a tear film flow being derived from the images, and a speed of movement of particles situated on the surface being measured.
In particular with very large magnification, it is possible to focus the tear film such that particles situated in the tear film are visible, for example dust particles or foreign bodies. Any movement of these particles is tracked and measured with respect to direction of movement and speed. The direction in which and the speed at which the tear film flows can be derived from this. This measurement is used to determine tear film quality more accurately.
In one embodiment of the method, the analysis instrument may have an evaluation apparatus, by means of which the images are analysed. The evaluation apparatus may advantageously be arranged in the analysis instrument itself and can enable processing of the images and a visualised output of the measurement results established by the evaluation apparatus. In particular, the evaluation apparatus may comprise data processing means, which can also carry out digital processing of the images. It is also conceivable for the data processing means to have a data store with a database, wherein the database may have comparative data sets of images or measurement parameters. For example, simplified conclusions regarding probable measurement results or corrections of measurement results can be drawn from comparative data sets of this type, for example as a result of image comparison. Evaluation can be accelerated considerably and measurement accuracy can be increased further.
The illumination device may also have at least one light source which emits polychromatic light in a predominantly visible spectrum, wherein a tear film on the surface can be determined from the images. A particularly accurate examination of the tear film is made possible in particular by the use of polychromatic, visible light to illuminate the eye and the tear film with the image pattern.
Furthermore, a degree of reddening of the eye can be determined from the images, a proportion of red in a region of the eye being measurable. A measurement of this type cannot be carried out using infrared light or monochromatic light due to the lack of colour reproduction. During the measurement process, a reddening of the region surrounding the iris of the eye can thus be measured by quantification of the red image portions due to the good colour reproduction of the polychromatic, visible light. The measurement can be carried out as a comparative measurement, for example by comparison with a reference image.
A tear film break-up time can also be derived from the images, wherein a change to the tear film can be measured. A tear film break-up time can be measured with normal magnification, and the measurement can be carried out under illumination with infrared light or visible light. The image patterns projected onto the surface of the eye, such as Placido rings, make it possible to identify any break-up of the tear film, in particular as a result of a change to the image pattern in question. A break-up time of a tear film can be considered to be a basic parameter for determining quality of the tear film.
Furthermore, a lipid layer on the tear film can be determined from the images, wherein the lipid layer can be measured by interference colours. A lipid layer is an outer layer of the tear film, wherein a central, aqueous layer and an inner layer adjacent to the cornea (mucin layer) follow after the lipid layer. The lipid layer is approximately 100 nm thick, prevents rapid evaporation of the aqueous layer and is formed from a secretion of the meibomian glands. Since the lipid layer is a very thin layer of the tear film, it can be measured very easily using interference colours. The eye or the tear film can thus be illuminated with polychromatic light, whereby the thickness of the interference colours or an interference pattern can be produced on the tear film by means of the aforementioned lipid layer. Possible tear film properties can thus be determined more accurately.
It is thus possible to determine a lipid layer thickness or thickness distribution of the lipid layer as well as the thickness thereof and also to examine the function of the meibomian glands on the basis of the measurable amount of lipids. A large magnification may preferably be selected for a measurement of this type.
Further advantageous embodiments of the method will emerge from the description of features of the claims.

This patent is subject to a terminal disclaimer.

Ophthalmological analysis instrument and method


A modular meter roller for an agricultural metering system. The modular meter roller includes a shaft that rotates. A first roller segment that defines a first aperture that receives the shaft. The first roller segment receives and meters flowable particulate material in a groove via rotation of the shaft. A first end plate couples to the shaft. The first end plate blocks removal of the first roller segment in a first axial direction. A second end plate removably couples to the shaft. The second end plate enables an exchange of the first roller segment with a second roller segment and blocks removal of the first roller segment in a second axial direction during operation of the modular meter roller.

The disclosure relates generally to a meter roller for an agricultural metering system.
Generally, seeding implements (e.g., seeders) are towed behind a tractor or other work vehicle via a mounting bracket secured to a rigid frame of the implement. Seeding implements typically include multiple row units distributed across a width of the implement. Each row unit is configured to deposit seeds at a target depth beneath the soil surface of a field, thereby establishing rows of planted seeds. For example, each row unit typically includes a ground engaging tool or opener that forms a seeding path (e.g., trench) for seed deposition into the soil. A seed tube (e.g., coupled to the opener) is configured to deposit seeds and/or other agricultural products (e.g., fertilizer) into the trench. The opener/seed tube may be followed by closing discs that move displaced soil back into the trench and/or a packer wheel that packs the soil on top of the deposited seeds.
In certain configurations, an air cart is used to meter and deliver agricultural product (e.g., seeds, fertilizer, etc.) to the row units of the seeding implement. The air cart generally includes a storage tank (e.g., a pressurized tank), an air source (e.g., a blower), and a metering system. The product is typically gravity fed from the storage tank to the metering system which distributes a desired volume of product into an air flow generated by the air source. The air flow carries the product to the row units via conduits extending between the air cart and the seeding implement. The metering system typically includes meter rollers that regulate the flow of product based on meter roller geometry and rotation rate.


A dialog management system functions to manage the dialog between a user of a computer system and one or more speech enabled software applications. The user provides spoken input to a microphone connected to the computer system, and hears responses from one or more applications through a speaker connected to the computer system. The dialog management system includes a dialog manager, a turn manager, a speak queue, dialog contexts, and dialog state. The dialog manager provides top-level control of the dialog and stores responses based on the user's spoken input in a speak queue for later output to the user. The turn manager controls delivery of the responses to the user based on the dialog context and the dialog state, to provide a polite asynchronous dialog with the user that enables the user to be in control of the dialog. The dialog context provides information about each dialog. The dialog state provides information about whose turn it is (computer or user) to speak.

Speech enabling mechanisms have been developed that allow a user of a computer system to verbally communicate with a computer system. Examples of speech recognition products that convert speech into text strings that can be utilized by software applications on a computer system include the ViaVoice™ product from IBM®, Armonk, N.Y., and Naturally Speaking Professional from Dragon Systems, Newton, Mass.
In particular, a user may communicate through a microphone with a software application that displays output in a window on the display screen of the computer system. A software application then may respond to the user by producing a speech output that may be played through a speaker that is connected to the computer system. The user may again communicate to the software application and thus, a dialog or conversation develops between the user and the software application. In such a dialog, a software application typically tries to manage the dialog, that is, manage the flow of responses to the user. In particular, in some conventional systems, a dialog manager is part of the software application or provided as a separate piece of software that serves to control the dialog.
In a conventional dialog management approach, the dialog manager software may serve several functions. For example, dialog management software can manage the flow of the conversation while maintaining the history and context of the conversation. In addition, the dialog management software may direct the course of the conversation, access a database to obtain content that may be used in responses to the user, and formulate the responses based on that content, to be given back to the user. In general, the dialog management software is dependent upon explicit dialog definitions that are coded into the speech application. In order for the dialog to proceed, the user responds to these dialog speech definitions in a specific manner. Certain responses from the user are expected in the dialog definitions. Typically, the user receives a specific menu of options or expected responses, and the user responds by selecting from that menu. The user's input must fall within a certain expectation of responses that are coded in the dialog definitions.
In one conventional dialog management system, the menu is provided by a touch-tone voice menu such as typically available on touch-tone telephones. In these conventional systems, the user contacts an application by dialing up a phone number. The touch-tone voice menu then provides a menu of responses or selections for the user. The user must respond by choosing within the range of selections indicated by these voice menus.

Method and Apparatus for managing dialog management in a computer conversation

International Business Machines Corporation


A computer generated hologram which forms a light intensity distribution on a predetermined plane by giving a phase distribution to a wavefront of incident light, the hologram comprising a plurality of anisotropic cells each including an anisotropic medium configured to change a polarization state of the incident light, and a plurality of isotropic cells each including an isotropic medium configured not to change a polarization state of the incident light, wherein a linearly polarized light component, in a first direction, of the incident light forms a first light intensity distribution on the predetermined plane, and a linearly polarized light component, in a second direction perpendicular to the first direction, of the incident light forms a second light intensity distribution different from the first light intensity distribution on the predetermined plane.

A projection exposure apparatus has conventionally been employed to fabricate a micropatterned semiconductor device such as a semiconductor memory or logic circuit by using photolithography (printing). The projection exposure apparatus projects and transfers a circuit pattern formed on a reticle (mask) onto a substrate such as a wafer via a projection optical system.
A resolution R of the projection exposure apparatus is given by:
                    R        =                              k            1                    ×                      λ            NA                                              (        1        )            where λ is the exposure light wavelength, NA is the numerical aperture of the projection optical system, and k1 is a process constant determined by, for example, a development process.
The shorter the exposure light wavelength or the higher the NA of the projection optical system, the better the resolution. However, it is difficult to further shorten the current exposure light wavelength because the transmittance of a general glass material decreases as the exposure light wavelength shortens. It is also difficult to further increase the NA of the projection optical system available at present because the depth of focus decreases in inverse proportion to the second power of the NA of the projection optical system, and because it is hard to design and manufacture lenses to form a high-NA projection optical system.
Under the circumstances, there have been proposed resolution enhanced technologies (RETs) of improving the resolution by decreasing the process constant k1. One of these RETs is the so-called modified illumination method (or oblique illumination method).
The modified illumination method generally inserts an aperture stop, which has a light-shielding plate on the optical axis of an optical system, in the vicinity of the exit surface of an optical integrator which forms a uniform surface light source, thereby obliquely irradiating a reticle with exposure light. The modified illumination method includes, for example, an annular illumination method and quadrupole illumination method that are different in the aperture shape of an aperture stop (i.e., the shape of the light intensity distribution). There has also been proposed another modified illumination method which uses a computer generated hologram (CGH) in place of an aperture stop, in order to improve the use efficiency (illumination efficiency) of the exposure light.
Along with an increase in the NA of the projection optical system, a polarized illumination method which controls the polarization state of exposure light is also becoming necessary to increase the resolution of the projection exposure apparatus. The polarized illumination method basically illuminates a reticle with not P-polarized light but S-polarized light alone, which has a component in the circumferential direction of concentric circles about the optical axis.
In recent years, there has been proposed a technique which exploits both the modified illumination method (the formation of a light intensity distribution having a desired shape (for example, a quadrupolar shape)) and the polarized illumination method (polarization state control).
For example, Japanese Patent Laid-Open No. 2006-196715 discloses a technique which implements both the modified illumination method and polarized illumination method using one element. Japanese Patent Laid-Open No. 2006-196715 controls the shape (reproduced image) of the light intensity distribution using a CGH, and controls the polarization state using form birefringence. More specifically, this technique forms one CGH by parallelly arranging a plurality of CGHs (to be referred to as "sub-CGHs" hereinafter) corresponding to light beams in the same polarization direction, and applies form birefringence corresponding to the polarization direction to each sub-CGH.
Japanese Patent Laid-Open No. 2006-49902 selectively uses a desired polarization mode by adopting a polarization controller as a unit for controlling polarization modes applied to a sub-CGH.
Japanese Patent Laid-Open No. 2006-5319 discloses a technique which can control the balance among four poles of a quadrupolar light intensity distribution typically formed by the modified illumination method and polarized illumination method. More specifically, Japanese Patent Laid-Open No. 2006-5319 forms sub-CGHs by dividing a CGH into four, and changes the intensity distribution of the incident light, thereby making it possible to change the pole balance of the reproduced image obtained by the CGH.
A technique associated with the design of a CGH has also been proposed in "Synthesis of digital holograms by direct binary search", APPLIED OPTICS, Vol. 26, No. 14, July 1987, 2788-2798.
However, because the prior arts require sub CGHs of types in a number equal to that of polarization directions of a reproduced image (target image) formed by a CGH, it is very difficult for them to form a target image whose polarization direction changes continuously.
Furthermore, when sub-CGHs are formed by dividing one CGH into a plurality of CGHs, an illuminance variation occurs in the reproduced image if the optical integrator cannot sufficiently correct the intensity distribution of the incident light (for example, if the light impinges on only some of these CGHs).
When a plurality of sub-CGHs are combined, unnecessary diffracted light is generated due to structural discontinuity that occurs at the boundary between the sub-CGHs, resulting in deterioration in the reproduced image obtained by the CGH. The structural discontinuity that occurs at the boundary between the sub-CGHs can be eliminated by improving the design of a computer generated hologram, but this poses another problem that the design cost increases enormously.
When the polarization modes are selectively used by the polarization controller, the use efficiency (illumination efficiency) of the exposure light decreases significantly (i.e., a loss in light amount increases).

Computer generated hologram including plural isotropic and anisotropic cells for forming combined intensity distribution, generation method, and exposure apparatus


Disclosed are one-component compositions that include: (1) an isocyanate-functional urethane acrylate and (2) a polyisocyanate containing allophanate and/or uretdione groups, wherein the one-component composition has a viscosity of less than or equal to about 800 mPa·s and an isocyanate content of greater than about 5% by weight, based on the weight of the one-component composition. Also disclosed are circuit boards and electronic components that are coated with such compositions.

The present invention relates to one-component, dual-curing conformal coating compositions.
Conformal coatings are used to protect circuit boards and electronic components from moisture and from premature corrosion. Polyurethane coatings are a popular choice for conformal coatings due to their high chemical resistance, flexibility, and hardness.
Coatings curable by actinic radiation (e.g. "UV coatings") find use as conformal coatings as such coatings may be cured relatively quickly by exposure to a radiation source, typically UV light. The fast cure allows manufacturers to increase throughput. However, because circuit boards and other electronic components have highly contoured surfaces, such UV coatings, when used as conformal coatings, suffer from a phenomenon whereby areas of the coating which cannot easily be exposed to UV light due to the contours (i.e. the "shadow" areas) remain uncured.
U.S. Pat. No. 4,424,252 describes the problem of "shadow cure" and solves such problem by the use of dual cure resins. Such resins cure by two mechanisms: a) exposure to UV light and b) curing by atmospheric moisture. The atmospheric moisture reacts with free isocyanate groups in the dual cure resin forming an amine group(s). The amine groups react with other isocyanate groups to form a polyurea. The curing by atmospheric moisture allows the areas of the coatings in the "shadows" to fully cure.
However, dual-cure polyurethane resins have suffered a disadvantage due to their relatively high viscosity. This issue is especially relevant for conformal coatings, due to the contoured shape of the substrate. Low viscosity resins are more favoured from a flowability standpoint—i.e. the low viscosity resins more easily flow around the contours of a circuit board and may more evenly coat such circuit boards.
Previous attempts to lower the viscosity of dual-cure polyurethane resins included adding a significant amount of reactive diluent to the dual-cure polyurethane resins. While the addition of reactive diluents served to lower the viscosity of the resin, it also reduced the wt. % of free isocyanate groups in the resin. This, in turn, has the effect of reducing the effectiveness of the moisture cure mechanism especially in shadow areas, which results in a coating with insufficient hardness and/or solvent resistance in such areas.
An object of the present invention is to provide coating compositions, which are suitable as conformal coatings and are characterized by their ability to be cured by exposure to actinic radiation, their ability to be cured by exposure to atmospheric moisture and their relatively low viscosity and that permit to obtain coatings with sufficient hardness and solvent resistance, especially in shadow areas
This object may be obtained with the coating compositions according to the invention, which are described below in greater detail.

One-component, dual-cure conformal coating compositions


Highly-coercive isometric iron oxide useful in magnetic toners for electrostatic photo-copying processes or for magnetic printers is produced by. (a) subjecting Fe.sub.3 O.sub.4 pigment produced in a wet process to oxidation and PA0 (b) subsequently reducing the oxidized pigment from (a) to produce highly-coercive Fe.sub.3 O.sub.4 pigment.

This application relates to a process for the production of highly-coercive isometric magnetic iron oxide pigments and to magnetic iron oxide pigments produced by this process and to the use thereof.
Magnetic iron oxide pigments of the composition FeO.sub.x, wherein 1.33.ltoreq.x.ltoreq.1.5, are used for the production of magnetic toners for electrostatic photo-copying processes or for magnetic printers. Isometric magnetite pigments having coercive field strengths (I.sup.H c) of from about 80 to 130 Oe are substantially used in conventional processes for this purpose. However, greater demands are made on these pigments in modern one-component toners. The coercive field strengths thereof have therefore to be within the range of from 180 to 250 Oe or above.
Two processes are essentially known at the present time for obtaining the coercive forces required. Those are:
1. by the incorporation of cobalt into the iron oxide pigments, PA0 2. by the use of needle-shaped pigments. PA0 (a) Fe.sub.3 O.sub.4 pigments produced in a wet process are oxidized and PA0 (b) are subsequently reduced to produce relatively highly-coercive Fe.sub.3 O.sub.4 pigments. PA0 (c) oxidized in a further step to produce relatively highly-coercive .gamma.-Fe.sub.2 O.sub.3 pigments or bertholloid mixed phase pigments.
However, the incorporation of cobalt is expensive and
in addition causes an undesirable fall in the I.sup.H c values as the temperature increases. Needle-shaped pigments produce directional dependence in the toner and rheological problems in the production thereof with the result that their use is accompanied by disadvantages.

Highly-coercive isometric iron oxides, a process for the production and the use thereof


A connector is provided for tensioning a guy line and connecting the guy line to a ground anchor or a tower. The connector may include a first body and a second body connected together by two or more threaded rods. The first body is connected to the ground anchor or the tower. The second body has a tapered cavity extending therethrough. The guy line extends through the tapered cavity, and wedges with a first and second inner arcuate surface that are vertically offset from one another are pushed into the tapered cavity. The first arcuate inner surface and the second arcuate inner surface may grip the guy line after the wedges have been pushed into the tapered cavity, while the vertical offsetting of the second arcuate inner surface reduces that stress on the guy line at an end of wedges. The first and second bodies may be drawn toward each other to tension the guy line.

The present disclosure relates generally to guy lines for supporting a tower, and more particularly, to a connector for connecting a guy line to a ground anchor or a tower.
Guy lines are used to support various kinds of towers, such as simple wood poles and metal or wood structures. As is understood by those of skill in the art, a guy line is typically a metal cable made up of a number of helically wound wires. Although various sizes of guy lines are possible, guy lines used for tower supports are commonly ½″ to 1¼″ in diameter. Typical rated loads for tower support guy lines are about 25,000 pounds minimum for a ½″ guy line and about 150,000 maximum for a 1¼″ guy line.
A guy line supports a tower by being connected to the tower near the top of the tower or at some intermediate height above the ground. From the top connection to the tower, the guy line extends down toward the ground at an angle away from the tower. At the ground, the guy line is connected to a ground anchor, which may be a metal screw-in anchor, a concrete block or other type of anchor. Thus, when installed, a guy line exerts a downward and outward pull on the tower. In order to fully support a tower, multiple guy lines are typically connected to the tower and ground anchors equally spaced around the tower.
During the installation process for a tower support guy line, the guy line is typically connected to the tower first. The bottom end of the guy line is then connected to the ground anchor, and is then tensioned to a specified load for the particular application. Various types of connectors have been used for connecting the bottom end of a guy line to a ground anchor. However, current guy line connectors are prone to failure at high loads (such as the guy line breaking), are difficult or complicated to install, and/or are expensive to make or use.

Adjustable transmission guy line connector


The method and apparatus are for controlling a longitudinal shifting of an elongated piece along a predetermined length SL as said piece moves transversely within a plane at a given speed PS. The apparatus comprises a longitudinal arm having a given length PL pivotable within the plane to shift the piece; a flexible link operatively mounted around the arm to contact the piece as the arm is pivoted to shift the piece; a controllable pivoting means for pivoting the arm according to an angle xcex8 determined in relation to the predetermined length SL and the given length PL; and a controllable driving means for driving the flexible link around the arm according to a speed SS determined in relation to the speed PS of the piece and the angle xcex8 so that the longitudinal shifting is controlled.

The present invention relates to an apparatus and a method for controlling a longitudinal shifting of an elongated piece along a predetermined length as the piece moves transversely within a plane at a given speed. According to a preferred application, the present invention relates to a board positioning apparatus and method for precise saw trimming. Such apparatus is generally mounted in front of a multiple saw trimmer.
Known in the art there is a mobile gate system with cylinders. Pneumatic cylinders are used for positioning a mobile gate. Limit switches are used for sensing the position of the gate. The gate is moved to a desired position and a lumber piece is moved against the gate. When the lumber piece is in position, an elongated arm lifts the lumber piece to keep its position for the trimming. One of the drawbacks with this equipment is that the accuracy of the displacement is in relation with the distance between the limit switches. Moreover, the stroke for one cylinder is typically limited to 6xe2x80x3 and for an additional displacement, it is then necessary to add another gate. Such system causes a rebound of the lumber piece on the gate and thus an additional imprecision occurs. The maximum speed of this system is generally 100 lumber pieces per minute.
Still according to the prior art, there is known a pivoting gate system with a cylinder. The operation of this system is similar to that of the mobile gate described above. The rebounds are however avoided since the lumber piece has a given continuation with the gate. The cylinders that are used are hydraulic cylinders with position sensors. One of the drawbacks of this equipment is that it requires an extensive maintenance and a high and expensive hydraulic power. The cylinders are also very expensive. The stroke of a cylinder is limited to 6xe2x80x3 and for an additional displacement, another gate has to be added. The maximum speed of this system is generally limited to 120 lumber pieces per minute.
Also known in the art, there is the Canadian published application no. 2,228,641 in the name of the applicant, wherein there is described an apparatus for positioning lumber pieces. This Canadian application corresponds to U.S. application Ser. No. 60/076,194. The apparatus comprises several levers mounted in rows. These levers are for slightly lifting the lumber pieces and thus preventing them to be longitudinally displaced by means of the aligning rollers. The lumber pieces are then pushed by means of wedges and slid over the levers. The geometry of the levers prevents abrupt movements of the lumber pieces. A drawback with this apparatus is that it is not compact and consequently requires a large space for its installation. As a matter of fact, when such positioning apparatus is mounted in existing plants, other important equipment may have to be removed to provide the necessary space for the installation of the apparatus.
It is an object of the present invention to provide a method and an apparatus that while compact can process a large number of elongated pieces per minute.
According to the present invention, there is provided an apparatus for controlling a longitudinal shifting of an elongated piece along a predetermined length SL as said piece moves transversely within a plane at a given speed PS, comprising: a longitudinal arm having a given length PL pivotable within the plane to shift the piece; a flexible strap operatively mounted around the arm to contact the piece as the arm is pivoted to shift the piece; a controllable pivoting means for pivoting the arm according to an angle xcex8 determined in relation to the predetermined length SL and the given length PL; and a controllable driving means for driving the strap around the arm according to a speed SS determined in relation to the speed PS of the piece and the angle xcex8 so that the longitudinal shifting is controlled.
Also according to the present invention, there is provided a method for controlling a longitudinal shifting of an elongated piece along a predetermined length SL as said piece moves transversely within a plane at a given speed PS, comprising steps of: (a) providing a longitudinal arm having a given length PL pivotable within the plane to shift the piece, and a flexible strap operatively mounted around the arm to contact the piece as the arm is pivoted to shift the piece; (b) pivoting the arm according to an angle xcex8 determined in relation to the predetermined length SL and the given length PL of the arm; and (c) driving the strap around the arm according to a speed SS determined in relation to the speed PS of the piece and the angle xcex8 so that the longitudinal shifting is controlled.

Apparatus and method for controlling a longitudinal shifting of an elongated piece along a predetermined length