A negative-voltage circuit for realizing a flash memory is installed independently and is applied selectively to word lines in response to signals sent from row decoders. Row decoders for specifying word lines need not be installed in the negative voltage circuit. The negative circuit can therefore be reduced in scale.

The nonvolatile semiconductor memory has an overall configuration, for example, as that shown in FIG. 1. In FIG. 1, N cell blocks 11.sub.l to 11.sub.N (for example, eight blocks) each having multiple transistor cells are arranged in a row. The cell blocks 11.sub.l to 11.sub.N are provided with bit line select circuits 12.sub.l to 12.sub.N and sense amplifiers/sense buffers 13.sub.l to 13.sub.N respectively.
A row address signal is supplied from a row address buffer 14 to each of the cell blocks 11.sub.l to 11.sub.N via a row decoder 15. A column address signal is supplied from a column address buffer 16 to each of the bit line select circuits 12.sub.l to 12.sub.N via a column address decoder 17. A voltage V.sub.S sent from a source power supply circuit 18 is applied to each of source electrodes of the transistor cells of the cell blocks 11.sub.l to 11.sub.N.
FIG. 2 shows the cell block 11, one of the cells blocks in the aforesaid nonvolatile semiconductor memory, and its peripheral circuitry. In FIG. 2, components identical to those in FIG. 1 bear the same reference numerals, of which a description will be omitted. In FIG. 2, the bit line select circuit 12 comprises n-channel MOS field-effect transistors Q1 to Qn. Column address signals Y1 to Yn are fed from the column decoder 17 to the gates of the transistors Q1 to Qn.
The cell block 11 comprises a total of n by n field-effect transistors Q11 to Qnn having floating gates and control gates. The gates of n transistors Qi1 to Qin (where, i=1, 2, etc., and n) arranged in tandem are provided with row address signals Xi sent from the row decoder 15 via word lines.
The drains of the n transistors Qli to Qni arranged in tandem are connected to the drains of the transistors Qi in the bit line select circuit 12 via bit lines. Voltage from the source power circuit 18 is applied to each of the sources of the transistors Q11 to Qnn. A cell amplifier 13a and a write buffer 13b are connected to each of the sources of the transistors Q1 to Qn.
In the foregoing semiconductor memory, when row addresses Xi and column addresses Yi are selected for writing, data read from the write buffer 13 are written in the transistors Qij of the cell blocks 11.sub.l to 11.sub.N. Writing is performed simultaneously on one bit per each of the cell blocks 11.sub.l to 11.sub.N or a total of N bits designated with the row addresses and column addresses. Data erasing is performed concurrently on all transistors in the cell blocks 11.sub.l to 11.sub.N.
In a flash memory, information is retained depending on the presence or absence of a charge in a memory cell. FIG. 3 shows an example of a structure of a memory cell. As shown in FIG. 3, a gate has a two-layered structure consisting of a control gate (CG) 25 and a floating gate (FG) 24. The control gate 25 is connected to a word line WLi and a drain (D) 23 is connected to a bit line BLi. Reference numeral 26 denotes a tunneling oxide film.
The flash memory is broadly divided into two types of what are referred to as NOR and NAND. These types differ from each other in a method of writing, reading, or erasing information into or from a memory cell. Taking the NOR type flash memory as an example, writing, reading, or erasing information into or from a memory cell will be described below.
When information is to be written in a memory cell having the aforesaid structure, as shown in FIG. 4, the word line WLi is set to Vpp (approx. 12 V), the bit line BLi is set to approx. 6 V, and the source S is set to 0 V. High voltage is then applied to the control gate CG and drain D. Current then flows into the memory cell. Part of the electrons flowing through the memory cell are accelerated due to the high electric field in the vicinity of the drain D, gain energy, and then goes beyond the energy barrier of an insulating film of the floating gate. The electrons are finally injected into the floating gate FG. The floating gate FG is not electrically coupled with other circuits, so it therefore can retain charges on a semi-permanent basis.
When information is to be read from a memory cell, as shown in FIG. 5, the word line WLi is set to Vcc (about 5 V), the bit line BLi is set to about 1 V, and the source S is set to 0 V. The memory cell is then selected by specifying the word line WLi and bit line BLi. The threshold value of the cell transistor varies depending on the charges retained in the floating gate FG. Current flowing through the selected memory cell varies depending on the information stored therein. The information therefore can be read out by detecting and amplifying the current.
The voltage levels of the control gate CG, drain D, source S, and substrate PS in the aforesaid operative states are set to the values listed in Table 1.
TABLE 1 ______________________________________ Voltages in modes in a prior art CG D S PS ______________________________________ Reading Vcc to 1 V 0 V 0 V Writing Vpp to 6 V 0 V 0 V Erasing 0 V Float Vpp 0 V ______________________________________
When information is to be erased from a memory cell, as shown in FIG. 6, the word line WLi is set to about 0 V and the bit line BLi is opened. In this state, the drain D is opened, about 0 volt is applied to the control gate CG, and a high voltage of about 12 volts is applied to the source S.
Since a high voltage is applied to the source S, deep diffusion is required in order to increase the resistivity of the diffused layer in the source. This hinders reduction in cell area.
For divided erasing, it is required that the Vss line in the source must partly have a different voltage. This leads to disconnection or an increased number of drive circuits. Eventually, chip size increases.
A solution to the above problem is to apply a negative voltage to the word line WLi. To be more specific, as shown in FIG. 7, a negative voltage (about-10 V) is applied to the control gate CG and Vcc (about 5 V) is applied to the source S. The drain D is opened. Erasing is then executed.
In this case, since a low voltage is applied to the source S, the resistivity of the source need not be intensified. This contributes to reduction in cell size. Partial erasing is enabled by selectively applying negative voltage to the control gates CG.
The aforesaid erasing method is a source erasing method in which charges in the floating gate FG are routed to the source. A channel erasing method is also available, wherein charges in the floating gate are routed to a channel; that is, a substrate. Even in this method, negative voltage is applied to the control gate. The channel erasing method is sometimes employed for the aforesaid NAND-type flash memory.
FIGS. 8 to 11 show the states of a memory cell with voltage applied according to various erasing methods. In FIGS. 8 to 11, the memory cell is an n-channel transistor.
FIG. 8 shows a state in which positive voltage is applied according to a channel erasing method. The drain D and source S are opened, and the control gate CG is set to 0 V. The high voltage Vpp is applied to the P well equivalent to a channel. In channel erasing, a triple-well structure shown in FIG. 8 is adopted because positive bias is applied to the channel.
FIG. 9 shows a state in which a positive voltage is applied according to the source erasing method. The drain D is opened, and then the control gate CG is set to 0 V. The high voltage Vpp is applied to the source S. The substrate is opened or set to 0 V.
FIG. 10 shows a state in which a negative voltage is applied according to the channel erasing method. The drain D and source S are opened, and the control gate CG is set to a negative voltage V.sub.BB. A positive voltage Vcc is applied to the p well equivalent to a channel. V.sub.BB -Vcc is applied between the control gate CG and channel.
FIG. 11 shows a state in which negative voltage is applied according to the source erasing method. The drain D is opened, and then the control gate CG is set to the negative voltage V.sub.BB. The source S is set to the positive voltage Vcc.
The resistivity of a junction in a source region can be improved by applying negative voltage to a control gate during erasing. This has the advantage of enabling reduction of a cell area. It is, however, a big problem how to realize application of negative voltage to the control gate.
It is, for example, conceivable to apply negative voltage from a row decoder to word lines. The voltage to be applied to a word line is changed depending on whether the word line is selected or not. In a flash memory, the voltage to be applied to a word line must be varied depending on whether the read mode or write mode is selected. When the row decoder is used to apply a negative voltage, the voltage to be applied to a word line must be changed to a negative voltage. A word line selected in the read or write mode has a higher voltage than other unselected word lines. For erasing, however, the selected word line must have a lower voltage than the unselected word lines. The level of applied voltage must therefore be reversed depending on the logic of selected or unselected word lines. This results in complex circuitry, making downsizing in possible.

Negative voltage circuit for a flash memory


The present invention relates to the manufacture of novel molecular sieve adsorbents for the separation of a gaseous mixture of oxygen, nitrogen and argon. The adsorbent is useful for the separation of oxygen and/or nitrogen from air. More specifically, the invention relates to the manufacture of a molecular sieve adsorbent, which is selective towards nitrogen from its gaseous mixture with oxygen and/or argon and argon from its gaseous mixture with oxygen.

The present invention relates to a process for the preparation of a molecular sieve adsorbent for selectively adsorbing nitrogen and argon from a gaseous mixture with oxygen.
Adsorption processes for the separation of oxygen and nitrogen from air are being increasingly used for commercial purposes for the last three decades. Oxygen requirements in sewage treatment, fermentation, cutting and welding, fish breeding, electric furnaces, pulp bleaching, glass blowing, medical purposes and in the steel industries particularly when the required oxygen purity is 90 to 95% is being largely met by adsorption based pressure swing or vacuum swing processes. It is estimated that at present, 4-5% of the world""s oxygen demand is met by adsorptive separation of air. However, the maximum attainable purity by adsorption processes is around 95% with separation of 0.934 mole percent argon present in the air being a limiting factor to achieve 100% oxygen purity. Furthermore, the adsorption-based production of oxygen from air is economically not competitive to cryogenic fractionation of air for production levels more than 100 tonne oxygen per day. Of the total cost of the oxygen production by adsorption processes, it is estimated that capital cost of equipment and power consumption are the two major factors influencing the overall cost with their share being 50% and 40% respectively. Along with the factors like process and system design, the adsorbent is the key component, which can bring down the cost of oxygen production by adsorption. The adsorbent selectivity and capacity are important parameters for determining the size of the adsorption vessels, compressors or vacuum pumps. It is desirable to have an adsorbent, which shows a high adsorption capacity as well as selectivity for nitrogen compared to oxygen. The improvement in these properties of the adsorbent directly results in lowering the adsorbent inventory of a system and hence the size and power consumption of the air compressor or vacuum pump. Furthermore, adsorbent having a high. nitrogen capacity and selectivity can also be used to produce reasonably pure nitrogen along with oxygen by evacuating nitrogen adsorbed on the adsorbent. Furthermore, adsorbents having both nitrogen and argon selectivity over oxygen can be used for producing high purity ( greater than 96%) oxygen from air.
It is, therefore, highly desirable, for an adsorbent to have good adsorption capacity and adsorption selectivity for a particular component sought to be separated.
Adsorption capacity of the adsorbent is defined as the amount in terms of volume or weight of the desired component adsorbed per unit volume or weight of the adsorbent. The higher the adsorbent""s capacity for the desired components the better is the adsorbent as the increased adsorption capacity of a particular adsorbent helps to reduce the amount of adsorbent required to separate a specific amount of a component from a mixture of particular concentration. Such a reduction in adsorbent quantity in a specific adsorption process brings down the cost of a separation process.
The adsorption selectivity of a component results from steric factors such as the differences in the size and shape of the adsorbate molecules; equilibrium effect, i.e. when the adsorption isotherms of components of a gas mixture differ appreciably; kinetic effect, when the components have substantially different adsorption rates.
It is generally observed that for a process to be commercially economical, the minimum acceptable adsorption selectivity for the desired component is about 3 and when the adsorption selectivity is less than 2, it is difficult to design an efficient adsorption process.
In the prior art, adsorbent which are selective for nitrogen from its mixture with oxygen and argon have been reported wherein the zeolites of type A, X and mordenite have been used after ion exchanging alkali and/or alkaline earth metal ions. However, the adsorption selectivity reported for the commercially used zeolite A based adsorbents for this purpose varies from 3 to 5 and adsorption capacity from 12-15 cc/g at 765 mmHg and 30xc2x0 C. The efforts to enhance the adsorption capacity and selectivity have been reported by increasing the number of exchangeable cations into the zeolite structure by modifying the chemical composition of the zeolite. The adsorption selectivity for nitrogen has also been substantially enhanced by exchanging the zeolite with cations like lithium and/or calcium in some zeolite types.
Zeolite A having a specific amount of calcium has been commercially used for oxygen production from air by selectively adsorbing nitrogen. However, presently used adsorbent has the following limitations:
Low adsorption capacity compared to other commercially used adsorbents.
Low adsorption selectivity.
It gives oxygen with only 95% maximum purity.
Sensitivity to moisture.
It needs multiple exchange with calcium salt.
The activation of the adsorbent requires much care, in order to prevent the hydroxylation.
R. V. Jasra et al. reviewed the recent status of pressure swing adsorption as a process for separating multi component gas mixture in xe2x80x9cSeparation of gases by pressure swing adsorptionxe2x80x9d; Separation Science and Technology, 26(7), pp. 885-930, 1991, The application of a new generation of adsorbents were described in detail. In xe2x80x9cAdsorption of a Nitrogen-Oxygen mixture in NaCaA zeolites by elution Chromatographyxe2x80x9d, Ind. Eng. Chem. Res. 1993, 32, 548-552, N. V. Choudary et al. describes the influence of calcium content on adsorption of nitrogen and oxygen is studied on various NaCaA zeolite samples. N. V. Choudary et al. describes the adsorption and desorption of nitrogen, oxygen and argon in mordenite type zeolite having different Si/Al ratios in xe2x80x98Sorption of nitrogen, oxygen and argon in mordenite type zeolitesxe2x80x99, Indian Journal of Chemistry Vol. 38A January 1999, pp.34-39. The heat of adsorption of nitrogen and argon in mordenite, NaA and NaX were compared to revels the sorbate interactions with extra-frame work sodium ions as well as lattice oxygen atoms.
Reference may be made to J. J. Collins et al in U.S. Pat. No. 3,973,931(1976) entitled xe2x80x9cAir separation by adsorptionxe2x80x9d, wherein an adiabatic pressure swing process for air separation by selective adsorption in atleast two zeolitic molecular sieve beds in which air is introduced at below 90xc2x0 F., the coldest gas temperature in the inlet end is 35xc2x0 F., delta T atleast 15xc2x0 F., the inlet end is heated to maintain the gas at maximum of at least 20xc2x0 F. warner than without heating, but below 175xc2x0 F. The main drawback is it require heating and temperature control in the air separation process.
C. G. Coe et al. in U.S. Pat. No. 4,481,018 (1984) entitled xe2x80x9cPolyvalent ion exchanged adsorbent for air separationxe2x80x9d, describes the use of a thermally activated polyvalent ion exchanged faujasite-containing compositions with selectivity 3.4 to 6.7 at 30xc2x0 C. for the separation of air into oxygen and nitrogen. The drawbacks are the thermal activation process requires very slow heating to prevent hydroxylation and the selectivity of the adsorbent is only 3.4 to 6.7 at 30xc2x0 C.
S. Sircar et al in U.S. Pat. No. 4,557,736 (1985) entitled xe2x80x9cBinary ion exchanged type X zeolite adsorbentxe2x80x9d, describes the use of an adsorbent comprises a binary ion exchanged type X zeolite, in which 5%-40% of the available ion sites are occupied by calcium and 60%-95% of the available ion sites are occupied by strontium is used for the adsorption of nitrogen from an air stream at superambient pressure to produce an oxygen rich product streem. The main drawback is the preparation of the adsorbent requires multistage cation exchange process.
S. Sircar in U.S. Pat. No. 4,756,723 (1988) entitled xe2x80x9cPreparation of high purity oxygenxe2x80x9d, describes the use of a single stage pressure swing adsorption method for the production of approximately 95% pure oxygen. The main drawback is the maximum attainable oxygen purity is only 95%.
C. C. Chao in U.S. Pat. No. 4,859,217 entitled (1989) xe2x80x9cProcess for separating nitrogen from mixtures, thereof with less polar substancesxe2x80x9d, wherein highly lithium exchanged low silica form of zeolite X containing more than ninety percent lithium cations are used for the selective adsorption of nitrogen from less polar gases. These adsorbents were prepared by lithium exchanging with 4-12 fold excess LiCl3 solution. The main drawbacks are the adsorbents are highly moisture sensitive and the lithium exchange requires 4-12 fold excess LiCl3 solution.
C. G. Coe et al. in U.S. Pat. No. 4,943,304 (1990) entitled xe2x80x9cProcess for the purification of bulk gases by using chabazite adsorbentsxe2x80x9d, which provides a process for the selective adsorption of one or more minor constituents from a bulk gas stream using a chabazite. The main drawback is the known methods for preparing commercially useful synthetic chabazites are not practical since they suffer from low yields, poor product purity, long crystallization times and are difficult if not impractical to scale up.
C. C. Chao in U.S. Pat. No. 4,964,889 (1990) entitled xe2x80x9cSelective adsorption on magnesium containing clinoptilitesxe2x80x9d, in which gases having molecular dimensions equal to or smaller than nitrogen are selectively adsorbed and separated from other gases having molecular dimensions higher than nitrogen. The main drawback is the particle size of the commercial clinoptilolite varies and the particle size of the clinoptilolite will affect the speed and completeness of the ion exchange reaction.
G. Reiss in U.S. Pat. No. 5,114,440 (1992) entitled xe2x80x9cProcess for the adsorptive-oxygen enrichment of air with mixture of calcium zeolite A molecular sieve by means of vacuum swing adsorptionxe2x80x9d, which gives a process for oxygen enrichment of air by means of vacuum swing adsorption using CaA molecular sieve. The drawbacks of this adsorbent are low nitrogen adsorption capacity, low selectivity of nitrogen over oxygen, its preparation needs multistage calcium exchange and its activation process requires very slow heating to prevent hydroxylation.
C. G. Coe et al in U.S. Pat. No. 5,152,813 (1992) entitled xe2x80x9cNitrogen adsorption with a Ca and/or Sr exchanged lithium X zeolitexe2x80x9d, which is directed to a process for separating nitrogen from gas mixtures containing oxygen, hydrogen, argon or helium by use of an at least binary exchanged X-zeolite having lithium and calcium and/or strontium ions in ratio of preferably 5% to 50% calcium and/or strontium and 50% to 95% lithium. The main drawbacks are the preparation of the adsorbent requires multistage cation exchange, its activation process requires very slow heating to prevent hydroxylation and adsorbent is highly sensitive to moisture.
C. C. Chao et al.in U.S. Pat. No. 5,174,979 (1992) entitled xe2x80x9cMixed ion exchanged zeolites and processes for the use thereof in gas separationsxe2x80x9d, wherein lithium/alkaline earth metal X zeolites in which the lithium:alkaline earth metal equivalent ratio is from 95:5 to about 50:50 and lithium/alkaline earth metal A zeolites in which the lithium: alkaline earth metal equivalent ratio is from 10:90 to about 70:30 are found useful for the separation of oxygen and nitrogen from a gas mixture. The main drawbacks are the preparation of the adsorbent requires multistage cation exchange, nitrogen selectivity is only 2-7 and the adsorbent is highly moisture sensitive.
T. R. Gafney et al. in U.S. Pat. No. 5,266,102 (1993) entitled xe2x80x9cOxygen VSA process with low oxygen capacity adsorbentsxe2x80x9d, wherein adsorbents with moderate nitrogen capacity and a high selectivity is used for the separation by VSA process. The main drawbacks are the maximum attainable oxygen purity is only 95% and adsorbent with low nitrogen capacity was used for the separation process.
C. C. Chao in U.S. Pat. No. 5,454,857 (1995) entitled xe2x80x9cAir separation processxe2x80x9d, wherein 60 to 89 equivalent percent calcium exchanged forms of zeolite X having silica/alumina ratio in the range of 2.0 to 2.4 is used in a temperature range of 50xc2x0 C. to xe2x88x9220xc2x0 C. and pressure range of 0.05 to 5 atmospheres. The main drawbacks are the preparation of the adsorbent requires multistage cation exchange and its activation process requirs very slow heating to prevent hydroxylation.
F. R. Fitch et al in U.S. Pat. No. 5,464,467 (995) entitled xe2x80x9cAdsorptive separation of nitrogen from other gasesxe2x80x9d, where in type X zeolites whose charge compensating cations are composed of 95 to 50% lithium ions, 4 to 50% of one or more of aluminum, cerium, lanthanum and mixed lanthanides and 0 to 15% of other ions were used for selectively adsorb nitrogen from gas mixture. The main drawbacks of this adsorbent are its high affinity towards moisture and its preparation requires multistage cation exchange from 5 to 10 fold lithium chloride solutions.
C. C. Chao et al. in U.S. Pat. No. 5,698,013 (1997) entitled xe2x80x9cNitrogen selective zeolitic adsorbent for use in air separation processxe2x80x9d, wherein using 60 to 89 equivalent percent calcium exchanged forms of zeolite X having SiO2/Al2O3 ratio with in the range of 2.0 to 2.4, as selective adsorption for nitrogen in air separation process by pressure swing adsorption. The main drawbacks of this adsorbent are its high affinity towards moisture and its preparation requires multistage calcium exchange and its activation process requirs very slow heating to prevent hydroxylation.
T. C. Golden et al. in U.S. Pat. No. 5,779,767 (1998) entitled xe2x80x9cUse of zeolites and alumna in adsorption processesxe2x80x9d, wherein describes a process for the purification of air by adsorption. The main drawback is this adsorbent is useful only for the adsorption of carbon dioxide, water, hydrocarbons and nitrogen oxides from the gas mixtures.
N. Ogawa et al. in U.S. Pat. No. 5,868,818 (1999) entitled xe2x80x9cAdsorbents for air separation, production method thereof, and air-separation method using itxe2x80x9d, describes the use of crystalline zeolite X having an SiO2/Al2O3 molar ratio of not larger than 3.0, which contains at least 90 mol% lithium cations were used for the air separation by pressure swing adsorption. The main drawbacks of this adsorbent are its preparation requires multistage cation exchange and it is highly sensitive to small amount of moisture.
J. T. Mullhaupt et al. in U.S. Pat. No. 5,945,079 (1999) entitled xe2x80x9cOxygen selective sorbentsxe2x80x9d, describes an invention comprises a process for air separation using oxygen selective sorbent with enhanced selectivity, loading capacities and oxygen uptake rates have a transition metal complex in solid form supported on a high surface area substrate. The drawbacks of this adsorbent are (a) The adsorption is not physical adsorption and hence it is not completely reversible, (b) The preparation and handling of the adsorbent is very difficult and (c) the use of this adsorbent is not commercially economical.
N. V. Choudray et al in No. U.S. Pat. No. 6,030,916 (2000) entitled xe2x80x9cProcess for the preparation of a molecular sieve adsorbent for selectively adsorbing nitrogen from a gaseous mixturexe2x80x9d, describes the preparation of molecular sieve adsorbents containing yttrium and alkali and/or alkaline earth metals as the extra framework exchangeable cations, useful for the separation of oxygen and/or nitrogen from air. The main drawback is the yttrium exchange process requires several cycles to obtain the adsorbent having high nitrogen selectivity.
N. V. Choudray et al in U.S. Pat. No. 6,087,289 (2000) entitled xe2x80x9cProcess for the preparation of a molecular sieve adsorbent for selectively adsorbing oxygen from a gas mixturexe2x80x9d, describes a process for the, preparation of a zeolte based adsorbent containing cerium cations are used for the selective adsorption of oxygen from a gas mixture. The main drawbacks of this adsorbent are its low oxygen capacity (around 3 cc/g at 30xc2x0 C. and 1 atm) and the oxygen selectivity is only in the low-pressure region.
M. Bulow et al. in U.S. Pat. No. 6,143,057 (2000) entitled xe2x80x9cAdsorbents and adsorptive separation processxe2x80x9d, describes the use of an adsorbent composites composed of microparticulate zeolites at least 90% of whose particles have a characteristic particle dimension not greater than about 0.6 microns and a macropore inert binder used for separating nitrogen or carbon dioxide from air. A mixture of type A zeolite, alpha zeolite, type X zeolite and type Y zeolite in which the available cation sites are occupied by a mixture of cations was used as the adsorbent for the selective adsorption. The main drawbacks of this adsorbent are its preparation involves several cycles of cation exchange process and the adsorbent is highly sensitive to moisture.
R. Jain et al. in U.S. Pat. No. 6,231,644 (2001) entitled xe2x80x9cAir separation using monolith adsorbent bedxe2x80x9d, describes the use of monolith bed for separating a first gaseous component from a gas mixture comprising the first gaseous component and a second gaseous component comprising passing the gaseous mixture into an adsorption zone. The main drawbacks of this adsorbent are its high affinity towards moisture and its preparation requires multistage ion exchange process.
N. V. Choudary et al. in Indian patent No. 181823 (1995) entitled xe2x80x9cA process for the preparation of a molecular sieve adsorbent useful in the oxygen enrichment of airxe2x80x9d, describes the use of a zeolite A based adsorbent containing clay binders were used to produce 85-95% pure oxygen by pressure swing adsorption. The main drawbacks of this adsorbent are the low nitrogen selectivity over oxygen (3-5 at 30xc2x0 C. and 1 atm), low nitrogen capacity (around 15 cc/g at 30xc2x0 C. and 1 atm), its high affinity towards moisture and its preparation requires multistage calcium exchange process.
The main object of the present invention is to provide a process for the preparation of a molecular sieve adsorbent for selectively adsorbing nitrogen and argon from a gaseous mixture with oxygen, which obviates the drawbacks as detailed above.
Another object of the present invention is to provide a nitrogen selective adsorbent based on synthetic zeolite.
Yet another object of the present invention is to provide argon selective adsorbent (compared to oxygen) based on synthetic zeolite.
Still another object of the present invention is to provide an adsorbent that can visibly refer the decay in adsorption capacity and selectivity due to moisture by its colour change.
Further object of the present invention is to provide an adsorbent with increased adsorption selectivity and capacity for nitrogen from its mixture with oxygen and/or argon.
Still another object of the present invention is to provide an adsorbent, which is selective to nitrogen and argon over oxygen and can be used commercially for the separation of air.
Yet another object of the present invention is to provide an adsorbent, which can be prepared by a single stage cation exchange process.
Accordingly, the present invention provides a xe2x80x9cProcess for the preparation of a molecular sieve adsorbent for selectively adsorbing nitrogen and argon from a gaseous mixture with oxygenxe2x80x9d, which comprises of a molecular sieve adsorbent represented by the general formula,
(Ag2O)x.(M2/nO)y.(Al2O3)6.(SiO2)12.wH2O
where the values of x varies from 4.8 to 6.0, y from 0.0 to 1.2, w being the number of moles of water and M is any metal ion having valancy n.
Accordingly, the present invention provides a single stage process for the preparation of crystalline molecular sieve adsorbent by silver ion exchange, used for selectively adsorbing nitrogen and argon from a gaseous mixture containing oxygen, said process comprising the steps of:
(a) mixing Zeolite A with an aqueous solution of silver salt;
(b) refluxing the solution at 30-90xc2x0 C. for 4-8 hours in dark to obtain a residue;
(c) filtering and washing the residue with water till the residue is free from silver ions; and
(d) drying below 85xc2x0 C. in air followed by under reduced pressure to obtain the crystalline molecular sieve adsorbent having a chemical composition (Ag2O)x.(M2/nO)y.(Al2O3)6.(SiO2)12.wH2O
An embodiment of the present invention, wherein steps (b)-(d) can be optionally performed in the following steps:
(a) mixing Zeolite A with equal amount of silver salt solution;.
(b) heating the mixture at a temperature in the range of 500-575xc2x0 C. in an inert atmosphere;
(c) washing the residue with water till the residue is free from silver ions; and
(d) drying the mixture at an ambient temperature under reduced pressure to obtain the crystalline molecular sieve adsorbent.
Yet another embodiment of the present invention, wherein the value of x varies from 1.2 to 6.0 moles.
Still another embodiment of the present invention, wherein the values of y varies from 0.0 to 4.8moles.
Yet another embodiment of the present invention, wherein w is number of moles of water.
Still another embodiment of the present invention, wherein M is a cation selected from the group consisting of sodium, calcium, potassium or lithium and most preferably sodium.
Still another embodiment of the present invention, wherein the zeolite selected is in the form of granule, powder and pellets.
Yet another embodiment of the present invention, wherein the aqueous solution of silver salt solution is selected from silver per chlorate (AgClO4), silver acetate or silver nitrate (AgNO3).
Further embodiment of the present invention, wherein the concentration of silver salt solution is in the range of 0.25%-15% by weight/volume of zeolite A.
Still another embodiment of the present invention, wherein the ratio of aqueous solution of silver salt with zeolite A is 1:80.
Yet another embodiment of the present invention, wherein said molecular sieve having a high nitrogen adsorption capacity upto 22.3 cc/g at 30xc2x0 C. and 765 mm Hg.
Further embodiment of the present invention, wherein said molecular sieve having selectivity for nitrogen over oxygen is 5-14.6 at 30xc2x0 C.;
Yet another embodiment of the present invention, wherein said molecular sieve having argon adsorption capacity upto 6.5 cc/g at 30xc2x0 C. and 765 mm Hg.
Further embodiment of the present invention, wherein said molecular sieve having selectivity for argon in the range of 1.2-2.0 at 30xc2x0 C.
Yet another embodiment of the present invention, wherein said molecular sieve having a low hydroxylation thereby preventing the necessity of slow heating.
Further embodiment of the present invention, wherein said molecular sieve having a high purification capacity of oxygen greater than 96%.
Yet another embodiment of the present invention, wherein 10 to 100 equivalent percentages of silver ions is loaded into zeolite in a single step using any water soluble silver salt selected from silver nitrate silver perchlorate or silver acetate.
Still another embodiment of the present invention, wherein the zeolite is. ion exchanged with 80 to 100 equivalent percent silver ions and activated molecular sieve adsorbent is orange red/brick red coloured.
Yet another embodiment of the present invention, wherein the molecular sieve adsorbent is dried at a temperature below 85xc2x0 C. preferably at a temperature in the range of 20xc2x0 C. to 80xc2x0 C. in air or under vacuum.
The invention is further explained in the form of the following embodiments:
Zeolites, which are microporous crystalline alumna-silicates, are finding increased applications as adsorbents for. separating mixtures of closely related compounds. Zeolites have a three dimensional network of basic structural units consisting SiO4 and AlO4 tetrahedrons linked to each other by sharing apical oxygen atoms. Silicon and aluminum atoms lie in the center of the tetrahedral. The resulting alumino-silicate structure, which is generally highly porous, possesses three-dimensional pores the access to which is through molecular sized windows. In a hydrated form, the preferred zeolites are generally represented by the following formula,
M2/nO Al2O3.xSiO2.wH2O
where M is a cation, which balances the electrovalence of the tetrahedral and is generally referred to as extra framework exchangeable cation, n represents the valancy of the cation and x and w represents the moles of SiO2 and water respectively. The cation may be any one of the numbers of cations, which will hereinafter be described in detail.
The attributes which makes the zeolites attractive for separation include, an unusually high thermal and hydrothermal stability, uniform pore structure, easy pore aperture modification and substantial adsorption capacity even at low adsorbate pressures. Furthermore, zeolites can be produced synthetically under relatively moderate hydrothermal conditions.
X-ray powder diffraction data was collected using PHILIPS X""pert MPD system equipped with XRK 900 reaction chamber. Comparing the X-ray diffraction data with literature X-ray data checked the crystallinity of the adsorbent particles. The X-ray diffraction at xe2x80x9cdxe2x80x9d values 12.1925, 5.489, 4.086, 3.2818, 2.9773 and 2.7215 were used for comparison.
The zeolite NaA powder [Na12(AlO2)12.(SiO2)12.wH2O] was used as the starting material. X-ray diffraction data showed that the starting material was highly crystalline. The zeolite NaA was mixed with a specified concentration of aqueous silver salt solutions in the ratio 1:80 and treated at 30-90xc2x0 C. for 4-8 hours in the dark. The residue was filtered, washed with hot distilled water, until the washings were free from silver ions (tested with sodium chloride solution) and dried at room temperature to 80xc2x0 C. in air and also under vacuum conditions as specified in the examples. The silver exchange completes in a single step since the equilibrium of the cation exchange reaction favors the easy formation of the product. The extent of silver exchange was determined by Atomic Absorption Spectroscopy.
Oxygen, nitrogen and argon adsorption at 15xc2x0 C. and 30xc2x0 C. was measured using a static volumetric system (Micromeritics ASAP 2010), after activating the sample at 350xc2x0 C. to 450xc2x0 C. under vacuum for 4 hours as described in the Examples. Addition of the adsorbate gas was made at volumes required to achieve a targeted set of pressures ranging from 0.5 to 850 mmHg. A minimum equilibrium interval of 5 seconds with a relative target tolerance of 5.0% of the targeted pressure and an absolute target tolerance of 5.000 mmHg were used to determine equilibrium for each measurement point. The adsorption and desorption are completely reversible, hence it is possible to remove the adsorbed gases by simple evacuation.
The heat of adsorption was calculated using the following equation
Heat of adsorption, xcex94adH0=R{[∂ ln p]/[∂(1/T)]}xcex8
where R is the universal gas constant, xcex8 is the amount of gas adsorbed at a pressure p and temperature T. A plot of Inp against 1/T should be a straight line of slope xcex94adH0/R.
The selectivity of two gases A and B is given by the equation,
xcex94A/B=[VA/VB]P,T
where VA and VB are the volumes of gas A and B adsorbed at any given pressure P and temperature T.
The important inventive steps involved in the present invention are that the molecular sieve adsorbent obtained, (i) is prepared by a single stage ion exchange process using aqueous solution of any silver salt in a temperature range of room temperature to 90xc2x0 C., (ii) is stable during the activation process, hydroxylation chance is very low and hence the activation process does not requre very slow heating, (iii) has a brick red/orange red colour afer the activation, which changes with decay of the adsorption capacity and selectivity due to the presence of moisture in the feed gas mixture, (iv) has, adsorption capacity and selectivity for nitorgen is maximum reported for any zeolite A based adsorbent so far and (v) has argon selectivity over oxygen, which will be useful for the production of oxygen with purity higher than 96%.

Process for the preparation of molecular sieve adsorbent for selective adsorption of nitrogen and argon

Council of Scientific and Industrial Research


An apparatus for receiving, dispensing, and regulating controlled substances is provided. Furthermore the apparatus may comprise a portable, handheld container which is tamper-resistant and can withstand severe physical manipulation. The apparatus may only permit the dispensing of medication according to a prescribed schedule and dosage.

The field of prescription medications is replete with dangerous, highly addictive, and potentially lethal drugs which, if not properly dosed, regulated and administered are susceptible to misuse, abuse, overdoses and toxicity which may or may not be intentional. In some situations improper dosing or an improper combination of medications may even result in death. The presence and accessibility to these medications in millions of homes presents a potentially significant safety risk to patients and other individuals who may come in contact with these medications. Drug poisoning is the second leading cause of injury-related deaths, accounting for 22,134 deaths in the United States according to a study published in 2013. Some of these deaths are the result of intentional overdose while others are the result of unintentional lethal combinations or doses of prescription medications. These overdose cases cost insurance companies approximately $72.5 billion in health care expenses each year.
Patients may also forget the appropriate schedule for taking their medication. Often, a patient may become confused or may have difficulty remembering whether or not they have taken their medication for the day, what dose they were supposed to take and whether or not the patient has individualized instructions.
Additionally, many medications, such as narcotics including opiates and their derivatives, central nervous system depressants such as benzodiazepines and stimulants such as Adderall are susceptible to abuse or black market transfers. A patient may become addicted to a controlled substance and attempt to take more than the appropriate dose prescribed by a healthcare professional or authorized individual capable of prescribing the substance. In other instances, a patient may attempt to sell controlled substances, which are only available through a prescription, to a non-prescribed individual or a non-prescribed individual may attempt to surreptitiously take drugs for themselves. Prescribed medications if not taken properly, or if taken by someone other than the prescribed patient, could result in serious physiological damage, psychological impairment and even death. Due to the vast number of prescriptions that are filled annually and the rising potential for drug abuse, there is a clear need for better medication security. Thus, a need exists for an apparatus, and a method for securely dispensing medications and other controlled substances according to a prescribed schedule and dosage using a portable, handheld container which is tamper-resistant and can withstand severe physical manipulation.


The invention relates to a method for supporting the quality of service (QoS) in packet data transmission between a wireless terminal (MT), having data communication with a radio access network, and a data network (LN), in which method data transmission between the terminal (MT) and the radio access network (2) is controlled by at least one mobile IP router (5, 5xe2x80x2, 5xe2x80x3). Further, in the method data is transmitted in radio flows between the wireless terminal (MT) and the mobile IP router (5, 5xe2x80x2, 5xe2x80x3). In the method, a flow label is defined for at least one radio flow and the desired quality of service is defined for the radio flow.

The present invention relates to a method as set forth in the preamble of the appended claim 1 for connecting data flows in wireless communication according to the Internet protocol, a system as set forth in the preamble of the appended claim 6, and an access point as set forth in the preamble of the appended claim 8.
The International Standardisation Organisation ISO has developed an open system interconnection (OSI) model for describing the distribution of data transmission in different layers. The layers are, listed from top downwards, an application layer (layer 7), a presentation layer (layer 6), a session layer (layer 5), a transport layer (layer 4), a network layer (layer 3), a data link layer (layer 2), and a physical layer (layer 1). In view of the present specification, the most essential layers are the physical layer, the data link layer, the network layer, and the application layer.
The term xe2x80x9cInternetxe2x80x9d is commonly used to describe an information resource from which information can be retrieved from a data processor, such as a personal computer (PC). The data processor communicates via a modem with a telecommunication network. This information resource is distributed world-wide, comprising several storage locations which also communicate with the telecommunication network. The Internet is made operable by defining certain data communication standards and protocols, such as TCP (transmission control protocol), UPD (user datagram protocol), and IP (Internet protocol), which are used for controlling data transmission between numerous parts of the Internet. The TPC and the UDP are involved with preventing and correcting data transmission errors in the data transmitted in the Internet; the IP is involved with data structure and routing. The currently used versions of the Internet protocol are IPv4 and IPv6.
Thanks to the growing popularity of open data systems, the Transmission Control Protocol/Internet Protocol (TCP/IP) communication protocol has become a generally used protocol whereby computers of different sizes and brands can communicate with each other. TCP/IP support is currently available for almost all operating systems. The network layer protocol of TCP/IP, the Internet Protocol IP, is intended to be routed by gateways, i.e. routers. The routing is conducted by means of IP addresses and routing tables.
In the Internet, each device has its own individual IP address. In the Internet protocol version IPv4, the IP address consists of 32 bits, i.e. it is a digit of four bytes which is divided in two parts: an organisation-specific network address and a network-specific device address. In the more recent Internet protocol version IPv6, the length of address fields has been added to 128 bits, which means in practice that an individual address can be reserved for all devices that are connected with the Internet network. FIG. 1 shows in IPv6 the blocks of the data packet in Internet messages.
The header block consists of the following elements:
Version IP version of 4 bits (=6),
Prio. priority of 4 bits,
Flow label 24 bit label for identifying the connection in the application layer,
Payload length 16 bit integer indicating the length of the payload, i.e. the length of the packet after the header in bytes,
Next header data of 8 bits determining the header immediately following the IPv6 header,
Hop limit integer counter of 8 bits which is reduced by one at the each device (node) which transmits the packet further; the packet is rejected if the value is reduced to zero,
Source address the 128 bit address of the sender of the original packet,
Destination address the 128 bit address of the intended recipient.
The header is followed by the payload block, i.e. the actual information to be transmitted.
Physically, the Internet consists of communication networks arranged in a hierarchy, for example local area networks (LAN), regional telecommunication networks and international telecommunication networks. These communication networks are coupled internally and externally with routers which transmit information from the transmitting terminal equipment or from the preceding router in the chain of data transmission, and route the information to the receiving terminal equipment or to the next router in the chain of data transmission.
Below in this specification, the transmitting terminal equipment and receiving terminal equipment will also be called by the common term Internet host. The Internet hosts can be typically used either as the source host SH and the destination host DH. In the present specification, the Internet hosts connected in a wireless manner with the Internet network are called a wireless terminal.
An Internet host, coupled to the Internet network via a local area network LAN, is either provided with a permanently defined Internet address or the address is a dynamic address generated by the server of the local area network (for example by using a dynamic host configuration protocol DHCP). In case the Internet host is coupled by a modem to a telecommunication network, the telecommunication terminal must ask for an Internet address from an Internet service provider to which the Internet host is registered. This is conducted e.g. according to a point-to-point protocol (PPP) formed above the Internet protocol layer. In both cases, the information to be transmitted in the Internet is routed to the Internet host possibly via several communication networks and routers from a remote host by using a determined Internet address.
The IP defines the transmission of the communication in packets (datagrams). The packet data transmission is one reason for the popularity of the Internet, because it allows transmission in bursts which does not require constant on-line connection and makes it possible that several Internet hosts are coupled in the same telephone connection. When a router receives a packet containing a destination address, the router routes the packet forward, if there is free capacity in the buffer memory of the router and at least one open telephone line. If there is not sufficiently memory space or no open telephone line available at the moment, the packet is rejected and the source host or the preceding router must try retransmission later. In general, the Internet does not support time-critical data transmission, and the method of best effort offered by the Internet protocol is sufficient.
In the transmission of packets according to the Internet protocol, the packets can be transmitted directly to the receiver only when the network elements of the addresses of both the host and the destination are the same. In other cases, the packets are transmitted to a router which takes care of transmitting the packets further, either to the next router or to the destination, if the recipient is in the network of the router. In each router, each packet entering the router is transferred from the data link layer according to the OSI model to the network layer, where the header of the packets is examined, and on the basis of the address data therein, a decision is made where the packet is to be transmitted. For transmission, the packets are transferred back to packets of the data link layer. The packets running the same path constitute a so-called communication stream. Because the Internet protocol has the character of a connectionless protocol, the above-mentioned operations must be conducted for each packet entering the router. If the communication layer is fast, for example in accordance with the asynchronous transfer mode ATM, the processing of the packets takes a significant part of the time used for transmission. Thus, the whole transmission capacity of the transfer line cannot be utilised effectively. For correcting this situation, e.g. Internet Engineering Task Force (IETF) has developed a solution in which an attempt is made to accelerate the routing of communication streams. In this solution, which is called Layer 3/Layer 2 switching (L3/L2 switching) or Multi Protocol Label Switching (MPLS), an attempt is made to switch the communication flows in the router directly on the data link layer, thereby reducing the need for performing time consuming routing on the basis of the address data of the network layer.
In an MPLS switching solution, so-called MPLS domains are formed. When a packet arrives to the router of such an MPLS domain, routing is conducted on the network layer. In this context, a short label of fixed length is added to the packet. Packets provided with such a label can be switched in the router by utilising the routing table of the data link layer, thereby avoiding the routing of the network layer. The label is used as an index in the table which determines the switching to the next router to be carried out in the router. Thus, in the MPLS domain, the routing of the network layer is thus conducted at the stage when the packet comes to the domain and, in a corresponding manner, when the packet leaves the domain. In contrast, it is possible to conduct a faster switching inside the domain in the data link layer. However, this solution requires that in each router of the MPLS domain, also a network layer protocol is implemented at least partially, as well as Internet protocol stack. In the MPLS domain, there are always three routers participating in the switching: the router that has transmitted the packet, the router switching the packet, and the next router receiving the packet. Because the routers are normally permanent, also the switching table can be made permanent and be updated in situations when new routers are added or routers in use are removed.
Telecommunication networks and the Internet are two significant world-wide communication networks, and wireless telecommunication terminals are being developed for coupling therewith and for their use. For example, cellular networks make it possible to couple a wireless telecommunication terminal to a telecommunication network and offer a high quality of service with circuit-switched technology. These cellular networks and other mobile communication networks can be utilised also for coupling to the Internet network and for utilising multimedia services. However, the circuit-switched system has the disadvantage that the connection from a wireless telecommunication terminal to a wireless communication network is turned on during the whole connection, which takes up the capacity of the wireless communication network and limits the number of simultaneous connections.
Data transmission in packet form improves the degree of capacity utilisation of the communication channel in general, not only for retrieving information from the Internet. For example, packet data transmission can be used in applications, such as voice calls, video negotiations and other communications according to different standards. However, some of these applications are time-critical. For example in a real-time voice call, the service of best effort offered by the Internet protocol may cause significant delays in the transmission and transfer of the audio signal, which affects the understanding of the received audio signal so that e.g. speech is almost or totally unintelligible. Moreover, the delay (the time consumed from the transmission to the receipt of the packet) may vary during the transmission of the audio signal, depending on e.g. the load of the communication network and variations in transmission errors. The same applies also to the transmission of a video signal in real time. There may also be situations where the users of the Internet do not want as long delays as occur in many cases for obtaining information from the Internet.
In radio links, data is typically transmitted in a channel which is a certain frequency range. Within one system, several channels can be available simultaneously. Further, in full duplex data transmission, there are separate transmitting and receiving channels, whereby for example a base station transmits on the transmitting channel to the terminal device and the terminal device transmits on the receiving channel to the base station. A problem with radio links is that the radio channel is a limited resource which limits e.g. the band width and/or number of channels that can be reserved as well as the data transmission rate available for the radio link. The radio channel is liable to disturbances, such as distortion of the received signal caused by multi-channel propagation which is due to the fact that the same signal is received at the destination through different routes at different times. To reduce the effect of disturbances, part of the data transmission capacity must be used for transmitting error connection data with the packets, and achieving a desired error probability rate may require several packet retransmissions, which reduces the capacity of the radio link.
In radio links, where several data transmission flows are transmitted on one channel, packets of these different data transmission flows are multiplexed. The transmission order can be affected by arranging packets of different data transmission flows in an order of priority, whereby packets of a flow with higher priority are transmitted more often than packets of a flow with lower priority. These include packets of a real-time application which are preferably made as short as possible. On the other hand, packets of applications with lower priority are often considerably longer than packets with higher priority. Such a long packet prevents the transmission of other packets as long as the transmission of the packet takes, unless a method for determining the quality of service is available also in a wireless connection. This may cause considerable delays also in the transmission of packets with higher priority, and reduce the quality of service.
Problems are caused in wireless communication also by mobility of the wireless terminal device, wherein as the connection of the terminal device changes to another base station, also the Internet connection has to be connected via this base station. Thus, also the routing may have to be changed.
It is an aim of the present invention to provide a method for connecting a radio flow and a flow according to the Internet protocol in a wireless Internet connection. The method of the invention is primarily characterised in what will be presented in the characterising portion of the appended claim 1. The system of the invention is primarily characterised in what will be presented in the characterising portion of the appended claim 8. Further, the access point of the invention is primarily characterised in what will be presented in the characterising portion of the appended claim 12. The invention is based on the idea that a label is added to the packets of the data link layer in order to define which packets of the IP flow and radio flow belong to the same data flow.
The present invention gives significant advantages to the methods and systems of prior art. By providing, in accordance with the invention, IP packets with a label, it is possible e.g. to implement the access point in a more simple manner, because implementation in the network layer level is thus not required at the access point, but a structure according to the data link layer and the physical layer added with the interlayer of the invention is sufficient therein. Thus, also the transmission of packets is accelerated, because time-consuming routing in the network layer can be avoided at the access point.


Retarded acid soluble well cement compositions which set into hard substantially impermeable masses and methods of using such compositions for forming removable cement plugs or seals in subterranean zones are provided. The compositions are comprised of magnesium oxychloride cement and a set retarder comprised of a water soluble borate and a sugar.

1. Field of the Invention
The present invention relates to retarded acid soluble magnesium oxychloride cement compositions and methods of utilizing such compositions for temporarily plugging or sealing subterranean zones.
2. Description of the Prior Art
In the drilling and completion of well bores penetrating subterranean formations containing hydrocarbons, voids and other highly permeable zones within the formations are often encountered. Such zones can cause a variety of problems including the loss of expensive drilling or completion fluids thereinto. Heretofore, lost circulation treatments involving various plugging materials such as walnut hulls, mica and cellophane have been used to prevent or lessen the loss of fluids from well bores. The disadvantages of such treatments include the potential for damage to hydrocarbon bearing formations as a result of the inability to remove the plugging materials therefrom, and the dislodgement of the plugging materials from highly permeable zones whereby fluid losses subsequently resume.
A more preferred technique for preventing lost circulation problems has been to temporarily plug voids or permeable zones with magnesium oxychloride cement compositions. Solid magnesium oxychloride cements can be removed with minimal damage to hydrocarbon bearing zones or formations by dissolution in acids. However, prior set retarded magnesium oxychloride cement compositions utilized in well drilling and completion applications have had relatively short thickening times, particularly at temperatures approaching 220.degree. F. As a result, prior retarded magnesium oxychloride cement compositions often can not be placed in a deep and/or hot subterranean zone before becoming too thick to pump.
Thus, there is a need for improved retarded acid soluble magnesium oxychloride cement compositions and methods whereby removable plugs or seals can be formed in relatively deep and/or hot subterranean zones therewith.

Retarded acid soluble well cement compositions and methods


A single transmission line couples multiple different antennas to corresponding radios using a low-loss signal selector made from a directional radio frequency coupler and a bandpass filter. A combiner receives signals from the antennas and combines those signals onto the one transmission line. The multiple, different-frequency signals on the transmission line are provided to a directional coupler having two outputs. One of the outputs from the directional coupler is routed to a first band pass filter having a pass band corresponding to a radio frequency required by a particular radio.

Most vehicles are manufactured with radios that receive the commercial AM and FM bands. Some vehicles are also manufactured with cellular telephone transceivers and navigation systems that include global positioning system receivers. Radio devices work best when they are provided with antennas that are sized, shaped and configured for the particular radio frequency band in which the devices operates. When a vehicle is provided with multiple radio devices that each require a correspondingly different antenna, coupling the multiple antennas to the multiple radio devices requires a corresponding multiple number of transmission lines. Reducing the number of transmission lines in a vehicle to one would reduce cost, reduce assembly time, reduce weight and increase the reliability of the vehicle. A method and apparatus for eliminating the need for a transmission line between each radio device and a corresponding antenna would be an improvement over the prior art.

GPS selector from a diversity/MIMO antenna cable


Methods and systems methods calculate an initial matrix by correlating scanned test device-dependent values to device-independent color space values of a test sheet. The initial matrix converts device-dependent values to device-independent color space values; however, the initial matrix does include some conversion error. Such methods then calculate an inverse matrix from the initial matrix. These methods and systems then calculate target device-dependent values by applying the device-independent color space values to the inverse matrix. The methods and systems derive final one-dimensional look-up tables that isolate the conversion error by correlating the scanned test device-dependent values to the device-independent color space values. These methods and systems then derive a final matrix specific to the scanner by first applying the scanned test device-dependent values to the final one-dimensional look-up tables before creating the final matrix. Then, this final matrix can be substituted for the previously calculated conversion matrix used for non-calibration operation.

Systems and methods herein generally relate to scanner calibration and more particularly to scanner calibration processes that transform scanned colors into device-independent color space.
In order to achieve high quality reproduction, it is often advantageous to calibrate optical scanners. Additionally, scanner output (which is often detected as combinations of red, green, and blue (RGB)) into a more precise, generic, device-independent format (such as HSV, CIE XYZ, and CIE L*a*b* values) that can be more easily utilized by all devices. For example, instead of transferring color signals in the RGB space from a scanner directly to color signals in the cyan magenta yellow black (CMYK) space to a color printer, a device-independent color space is commonly used as the intermediate color space for other evolved image processing, such as compression, decompression, enhancement, correction, and the like.
In general, traditional methods of scanner profiling are used to transform the color data (e.g., obtained from a scanner or a linear array sensor) in the device dependent color space to the device independent color space. These traditional methods of scanner profiling use, for example, a matrix or a look-up table (LUT). A 3×3 matrix relates a RGB input to a L*a*b* or XYZ output, with a linear in reflectance like RGB, and converting XYZ output to L*a*b* using standard formulas. Further improvements may be obtained by using a 4×3 matrix, where the additional row represents the offset terms. A look-up table transformation maps a RGB input to a L*a*b* output and often involves interpolation using available LUT entries.
Therefore, much work has been directed toward achieving high accuracy color space transformation. Often, in scanner device RGB to CIE XYZ conversion, a one-dimensional (1D) gray balancing look-up table (LUT) is applied to the input RGB, followed by a matrix conversion to transform the adjusted RGB to CIE XYZ. Such methods are able to produce incremental improvement in the quality of color space transformation, but in order to keep products competitive in terms of cost, quality and performance further improve in color accuracy (without restoring to computationally expensive algorithms) would be useful.

Scanner calibration using inverse matrix


Various embodiments illustrated and described herein provide one or more of systems, methods, and software operable to process multilayered documents including form fields. Some embodiments, are operable to process a new or modified background layer image to identify input fields, to match the identified fields with metadata in foreground layer data defining interactive input fields, and to modify the mappings of the input fields defined within the foreground layer of a page description language document as a function of identified input fields in the modified background layer image.

It has become increasingly common to create, transmit, and display documents in electronic format. Electronic documents have a number of advantages over paper documents including their ease of transmission, their compact storage, and their ability to be edited and/or electronically manipulated. A page in an electronic document can include various types of graphical elements, including text, line art, and images. Electronic documents are generally created by computer programs (also called application programs or simply applications) that can be executed by a user on a computer to create and edit electronic documents and to produce (directly or indirectly) printed output defined by the documents. Such programs include the ADOBE ILLUSTRATOR® and PHOTOSHOP® products, both available from ADOBE SYSTEMS INCORPORATED of San Jose, Calif. Computer programs typically maintain electronic documents as document files that can be saved on a computer hard drive or a portable medium such as a USB drive or floppy diskette. An electronic document does not necessarily correspond to a document file. An electronic document can be stored in a portion of a document file that holds other documents, in a single document file dedicated to the electronic document in question, or in multiple coordinated document files. Graphical elements in electronic documents can be represented in vector form, raster form, or in hybrid forms.
An electronic document is provided by an author, distributor, or publisher (referred to as "publisher" herein) who often desires that the document be viewed with a particular appearance, such as the appearance with which it was created. A portable electronic document can be viewed and manipulated on a variety of different platforms and can be presented in a predetermined format where the appearance of the document as viewed by a reader is as it was intended by the publisher.
One such predetermined format is the Portable Document Format ("PDF") developed by ADOBE SYSTEMS INCORPORATED. The class of such predetermined formats is often referred to as a page description language. An example of page-based software for creating, reading, and displaying PDF documents is the ADOBE ACROBAT® program, also of ADOBE SYSTEMS INCORPORATED. The ADOBE ACROBAT® program is based on ADOBE SYSTEMS INCORPORATED's POSTSCRIPT® technology, which describes formatted pages of a document in a device-independent fashion. An ADOBE ACROBAT® program on one platform can create, display, edit, print, annotate, etc. a PDF document produced by another ADOBE ACROBAT® program running on a different platform, regardless of the type of computer platform used. A document in a certain format or language, such as a word processing document, can be translated into a PDF document using the ADOBE ACROBAT® program. A PDF document can be quickly displayed on any computer platform having the appearance intended by the publisher, allowing the publisher to control the final appearance of the document. Another predetermined format is the XML Paper Specification page description language developed by Microsoft Corporation of Redmond, Wash. Tools that may be used to generate documents encoded according to one or more of these predetermined formats include word processing programs, printing adapters or drivers, spreadsheet programs, other document authoring programs, and many other programs, utilities, and tools.
Electronic documents can include one or more interactive digital input fields (referred to interchangeably as "input fields" and "form fields" herein) for receiving information from a user. An input field (including any information provided by a user) can be associated with a document file of an electronic document either directly or indirectly. Different types of input fields include form fields, sketch fields, text fields, and the like. Form fields are typically associated with electronic documents that seek information from a user. Form fields provide locations at which a user can enter information onto an electronic document. A text form field allows a user to enter text (e.g., by typing on a keyboard). Other types of form fields include buttons, check boxes, combo boxes, list boxes, radio buttons, and signature fields. Sketch fields are typically associated with electronic documents that contain graphical illustrations and/or artwork. Sketch fields provide locations at which a user can add graphical illustrations and/or artwork to an electronic document, such as by manipulating a pointing tool such as a mouse or digitizing pen. Generally, text fields can be associated with any electronic document. Text fields are locations at which a user can add text to an electronic document.

Document mapped-object placement upon background change


This method for making a transformer core comprises the following steps: (a) providing amorphous metal strip material, (b) winding said strip material onto an arbor in superposed layers, thereby forming a multi-layered core form, (c) applying coats of powder to said strip material before the strip material is wound onto the arbor, thereby causing predetermined adjacent ones of said layers by to be separated small distances to reduce the space factor of the core form, and (d) annealing the core form while said powder coatings are present between adjacent layers, thus enabling the powder to lessen the tendency of adhesions to develop between adjacent layers of amorphous metal during annealing.

In the general type of core-manufacturing method that we are concerned with, magnetic strip material is wrapped in superposed relationship about the window of the core to build up a core form, and the core form is later annealed at elevated temperature to relieve stresses therein. A problem that arises in such manufacture is that the pressure of the wrapping and other pre-annealing operations and the heat of the annealing operation often produce, within the core, regions where juxtaposed layers of strip material adhere together and form relatively low resistance paths, or shorts, between the adhering strip layers. Such internal adhesions or shorts are undesirable because they can produce within the core, transversely of the flux path therethrough, low resistance closed circuits for eddy currents; and such closed circuits have the detrimental effect of reducing the effective net cross-section of the core, the amount of such reduction being a direct function of the cross-sectional area bounded by such closed circuit or circuits.
Application Ser. No. 07/726,239--Lee et al, filed Jul. 5, 1991, issued as U.S. Pat. No. 5,134,771, assigned to the assignee of the present invention, and incorporated by reference herein, discloses several different methods for reducing the number of such internal shorts that are present in the final core. These methods all involve breaking up the internal shorts after they have formed during annealing.

Method for manufacturing an amorphous metal core for a transformer that includes steps for reducing core loss


The present invention provides combinations of specific binding proteins, such as immunoglobulins, that are designed to be true combinations, essentially all components of the combination being functional and compatible with each other. The invention further provides a method for producing a composition comprising at least two different proteinaceous molecules comprising paired variable regions, the at least two proteinaceous molecules having different binding specificities, comprising paired variable regions, at least two proteinaceous molecules having different binding specificities, comprising contacting at least three different variable regions under conditions allowing for pairing of variable regions and harvesting essentially all proteinaceous molecules having binding specificities resulting from the pairing.

Specific recognition plays an important role in modern medical biology. Receptor-ligand interactions, immune responses, infections, enzymatic conversions are all based on specific recognition between molecules. Of particular interest are specific protein-protein interactions, which give a vast array of possibilities to interfere in all kinds of biological processes. Throughout nature, biological processes are found that depend on more than one (simultaneous) protein-interaction. At the present time, it seems that interfering at more than one point in a biological process is going to be more effective than a single interference. Particularly in antibody therapy, it is seen that one (monoclonal) antibody is often not effective enough for treating a particular disorder and/or disease. Therefore, the attention of many medical researchers is now focused on combination therapies. Well-known examples of combinations of antibodies that are presently clinically pursued are for the treatment of non-Hodgkin's lymphoma, the combination of the already approved anti-CD20 antibody Rituxan with the anti-CD22 antibody Epratuzumab from AmGen, and for the treatment of Hepatitis B, a combination of two human antibodies being developed by XTL Pharmaceuticals (E. Galun et al., Hepatology (2002) 35:673-679). However, the combination of multiple (two or more) drugs (be it antibodies or other) has a number of technical, practical and regulatory drawbacks. The drugs were typically not designed as combinations and development with optimal clinical efficacy and compatibility may be a problem. As an example, conditions for stabilizing the one may be detrimental to stability of the other(s). Furthermore, multiple sources of recombinant production lead to multiple sources of risks, such as, viral contamination, prion contamination and the like.
The present invention provides combinations of specific binding proteins, such as immunoglobulins, that are designed to be true combinations, essentially all components of the combination being functional and compatible with each other. By producing true combinations, the present inventors have opened up an avenue of further improvements in both the production and properties of the combinations. These improvements and their advantages will become apparent from the following description.

Method for selecting a single cell expressing a heterogeneous combination of antibodies


A DC backup system is for providing emergency electric power to an electronic device powered by an input power source, and includes a battery backup unit and a battery control unit. The battery backup unit is operable to output state information indicating a state thereof, and test information associated with a self test performed thereon. The battery control unit is electrically connected to the battery backup unit for receiving the state information and the test information therefrom, and is configured to control, according to the state information and the test information, the battery backup unit to output electric power to the electronic device when the input power source fails.

Referring to FIG. 1, a conventional electricity architecture includes at least one alternating current (AC) transformer (e.g., two AC transformers 91, 92), at least one generator (e.g., two generators 93, 94), at least one uninterruptible power system (UPS) (e.g., two UPS's 95, 96), a power distribution unit (PDU) 97, an AC power shelf 98, a direct current (DC) bus 99, and a plurality of electronic devices (such as two servers 991, 992 and two storage devices 993, 994). The AC transformer 91, the generator 93 and the UPS 95 are electrically connected to the PDU 97 through a transmission line 10, and similarly, the AC transformer 92, the generator 94 and the UPS 96 are electrically connected to the PDU 97 through another transmission line 20. The PDU 97 is configured to distribute electric power from one of the transmission lines 10, 20 to the AC power shelf 98 such that the servers 991, 992 and the storage devices 993, 994 are powered by the electric power via the AC power shelf 98.
Each of the AC transformers 91, 92 is configured to receive electricity from a power plant or a front-end transformer, and to step down voltage of the electricity so as to output an AC output to the PDU 97 through the corresponding one of the transmission lines 10, 20.
The generators 93, 94 are, for example, diesel generators. Each of the generators 93, 94 is configured to detect voltage value of the AC output from the respective one of the AC transformers 91, 92. When it is detected that the AC output from the respective one of the AC transformers 91, 92 is abnormal (for example, the voltage value is lower than a predetermined value), the generator 93, 94 operates to provide AC electricity to the PDU 97 through the corresponding one of the first and second transmission lines 10, 20.
Each of the UPS's 95, 96 includes an AC-to-DC converter, a power storage module, a DC-to-AC converter and a control unit. The control unit of each UPS 95, 96 is configured to detect voltage value at the corresponding one of the first and second transmission lines 10, 20. The control unit controls the AC-to-DC converter to convert the electric power, which is received from the corresponding one of the first and second transmission lines 10, 20, into DC power, and to store electric energy of the DC power in the power storage module when the voltage value is within a normal range. The control unit controls the DC-to-AC converter to release the energy stored in the power storage module to the corresponding one of the first and second transmission lines 10, 20 when the voltage value is lower than a predetermined voltage value.
Since each of the UPS's 95, 96 includes the AC-to-DC converter and the DC-to-AC converter, the volume of each of the UPS's 95, 96 is relatively large, making installation difficult. In addition, since electric power conversion (AC-to-DC or DC-to-AC) is required both in storing electric energy into the power storage module and in releasing electric energy from the power storage module, efficiency of the energy transformation is relatively low.


An intercourse assistance device for reducing the length of a penis that enters a vagina. The intercourse assistance device has a support body with a front side and a rear side. The support body is made of resistantly-rigid material. The device includes a region of deformably-soft material monolithically positioned centrally within the support body. The deformably-soft material is adapted to deform when in contact with the penis. The device also includes a reflexively-closable opening cut out from the region of reflexively-deformable material. The opening is adapted to removably receive the penis.

Dyspareunia, or painful intercourse, can be caused by many physical and psychological conditions. It can occur just before, during, or after intercourse. Painful intercourse may be caused by endometriosis, radiation, chemotherapy, ovulation, menstruation, pregnancy, a previous surgery, scar tissue, menopause, and vaginal atrophy. These conditions may lead to less elastic vaginal tissue, vaginal shortening, and swelling. All of these vaginal changes may lead to painful intercourse.
Dyspareunia may also be a result of the length of a man's penis, more specifically the length of the penis with regard to his partner's vagina. When the man's penis is long, pain can occur during penetrations. However, for completely healthy women, increased length of the penis may result in the lower portion of the uterus, or cervix, being contacted, especially during thrusting that can be extremely painful.
For these reasons, there exists a need for improvements that would help reduce dyspareunia.


A diagnostic testing utility is used to perform online path diagnostic tests to troubleshoot components in a path that contribute to performance degradations and check application level data integrity, while traffic is allowed to flow as normal. To perform the diagnostic tests, two HBA or CNA ports at each end of a path are identified and used to send test frames to perform the diagnostic tests. The entire diagnostic procedure is performed without taking any ports or servers offline.

Storage area networks (SANs) are typically implemented to interconnect data storage devices and servers or hosts, using network switches to provide interconnectivity across the SAN. SANs may be complex systems with many interconnected computers, switches, and storage devices. The switches are typically configured into a switch fabric, and the hosts and storage devices are connected to the switch fabric through ports of the network switches that comprise the switch fabric. Most commonly, Fibre Channel (FC) protocols are used for data communication across the switch fabric, as well as for the setup and teardown of connections to and across the fabric, although these protocols may be implemented on top of Ethernet networks.
Many SANs rely on the FC protocol. The FC protocol defines standard media and signaling conventions for transporting data in a serial fashion. It also provides an error correcting channel code and a frame structure for transporting the data. Many FC switches provide at least some degree of automatic configurability. For example, they may automatically sense when a new inter-switch link (ISL) becomes active, and may initiate an initialization process to discover what the link connects to. The switch may automatically determine various parameters for the link (e.g. link speed). As FC networks are created, updated, maintained and de-commissioned, switches may be enabled, disabled or reconfigured, and links may be added or removed.
Over time, FC networks have become more complex, with multiple fabrics involving several switches that use inter-switch links (ISLs) connected to switch ports (E_ports) on the switches. At the same time as FC networks have become more complex; the network speeds have also increased significantly. As faster networks are implemented, media and cable tolerance become more important for avoiding degraded performance and cyclic redundancy check (CRC) errors. As larger networks are developed, diagnosis of optics and cables become more and more time consuming and intrusive. Current switches have two basic types of built-in diagnostics. First, the SFP electro-optical modules have digital diagnostics, but these only operate at the SFP component level. Second, a command line interface (CLI) tool may be provided to allow frames to be injected and circulated on a specific link, but the end result is only a good and bad indication, which does not greatly aid diagnosis. A third method of diagnosing ISL errors is to use D-ports, as discussed in U.S. patent application Ser. No. 13/047,513, the entire disclosure of which is hereby incorporated by reference. The D-port system would require that two ports be taken offline while the system performs the desired diagnostics. As such it is not useful for performing online diagnostics. Thus, troubleshooting suspected link and path errors with the existing tools is time consuming, can become a daunting task and/or requires that taking some ports offline. The use of external separate testing tools is also cumbersome and brings along separate problems not present with built-in tools.
Thus, it would be desirable to implement an efficient network diagnostic method to more efficiently troubleshoot larger networks, thereby improving the speed, efficiency, and reliability of these networks.

This patent is subject to a terminal disclaimer.


A system for reading substrate carriers that includes at least one overhead transport vehicle (OHT) utilizing at least one device for at least one of sensing and/or reading a substrate carrier, and/or wafers arranged therein, when the substrate carrier is proximate the at least one overhead transport vehicle. A method of sensing or reading a substrate carrier includes sensing and/or reading a substrate carrier and/or wafers arranged therein with the overhead transport vehicle.

Semiconductor manufacturing facilities typically utilize a number of buffer storage areas, a number of bays that includes processing tools, an overhead track system, and a number of overhead traveling vehicles or transporters (OHTs). The buffer storage areas store substrate carriers which are also known as front opening unified pods (FOUPs), standard mechanical interface (SMIF) pods, and cassettes.
It is also known to utilize overhead buffer storage systems (aka zero footprint storage) in semiconductor manufacturing facilities. These overhead storage systems are typically suspended from a ceiling in a manner similar to the track system. An OHT can access the overhead buffer storage system via the track and functions to transfer the substrate carriers between, among other locations, the processing tools and the overhead buffer storage system.
However, it sometimes occurs that the control system of the semiconductor manufacturing facility is rendered blind as to the specific location of each substrate carrier. This can occur when the data provided to the control system is lost or corrupted. When this occurs, the OHTs must go out to the areas where the substrate carriers are stored, retrieve each substrate carrier, and deliver it to a data collection area (i.e., one of the floor storage buffer locations or one of the processing tools). These data collection locations have RFID readers which can read the RFID tags of the substrate carriers.
This process is very time consuming and represents time that the facility is not processing wafers, which is, of course, very costly. For example, in a facility having 206 buffer storage locations in three different bays or in a facility having about 300 buffer storage locations in four different bays, one OHT can retrieve and transfer a substrate carrier to a read station in about 2 minutes. This means that the OHT will require 6.8 hours to identify all of the substrate carriers. If two OHTs are used, the OHTs will require 3.4 hours to identify all of the substrate carriers. If an entire fabrication facility with 5000 buffer locations needs to have the substrate carriers read, this can mean that all of the OHTs will be tied up in identifying the substrate carriers instead of delivering product to the processing tools, creating a potential bottleneck for the facility.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described herein.

Semiconductor automation buffer storage identification system and method

International Business Machines Corporation


A quad interconnect system for receiving quad connectors and connecting their quad contacts to corresponding signal traces on a circuit board, provides a grounded electromagnetic shield around each quad connector in a simple arrangement that occupies a minimum amount of space on the circuit board. A housing with quad-receiving passages that receive the quad connectors, is constructed of metal to provide a grounded metal shield closely around each quad connector. Only a few grounding devices (less than half the number of quad-receiving passages) are used to connect the metal housing to a grounded trace on the circuit board, to minimize the space taken up on the circuit board. Sheet metal clips with tines that engage shoulders at the rear ends of flanges on each metal shell of a quad connector, have short tabs with edges that also engage the shoulders to assure good electrical connection and minimize vibration. Quad connectors can be used that do not have shells, but which are closely surrounded by smaller diameter grounded housing passage walls.

Quad connectors are connectors that each has four quad contacts lying in a quad insulator, with the insulator usually surrounded by a metal shell. A group of such quad connectors can be terminated to a circuit board by the use of a quad interconnect assembly. Such a quad interconnect assembly has an insulative housing with many quad-receiving passages and an insulative plate with many interconnect pins. A quad connector is inserted forwardly into a passage until the front ends of its quad contacts connect to rear ends of four of the interconnect pins. The pins have front ends that project from the insulative plate and that can be inserted into signal holes in the circuit board and soldered thereat to signal traces on the circuit board.
Noise, which may arise from signals in the many close quad contacts and connectors, is reduced by connecting each quad shell to ground potential. This previously has been accomplished by use of a grounding element for each quad connector, which had a rear end lying at the rear of each passage and in contact with the rear of a quad shell in the passage. Each grounding element had a plurality of pins extending though and forward of the insulative plate, for insertion into grounding holes in the circuit board. Such grounding elements take up space not only at-the rear of each passage, but on the circuit board. This can result in the need for larger spacing between quad-receiving passages and a larger circuit board with more holes, which results in greater expense and a larger apparatus. A quad interconnect assembly of simpler and smaller design would be of value.


We disclose herein a method for heating a gas sensing material formulation on a microhotplate which comprises: a dielectric membrane formed on a semiconductor substrate comprising an etched portion; and the gas sensing material formulation being located on one side of the dielectric membrane. The method comprising: selectively heating the gas sensing material formulation using an infra-red (IR) heater located over the substrate, and controllably cooling the semiconductor substrate using a cooling baseplate provided under the substrate and using an insulating medium located between the substrate and the cooling base plate so that a gas sensing structure is formed on said one side of the dielectric membrane from the gas sensing material formulation.

Metal oxide (MOX) gas sensors are a well-established technology and are based on the deposition of a metal oxide film onto sensing electrodes defined on or within a suitable substrate. The substrate could be a ceramic or, more recently, a silicon substrate. The deposition process could use a thin film technology, such as sputtering, atomic layer deposition or chemical vapour deposition, or a thick film technology such as screen printing, drop coating or ink jetting. In the latter case the film could be deposited in the form of an ink or paste where metal oxide grains are held in suspension in a suitable vehicle, often comprising of organic solvents. This vehicle generally needs to be driven off the powder and any organic compounds decomposed to leave an uncontaminated metal oxide. Furthermore, the metal oxide grains generally need to be "fired" to form a mechanically robust, stable and porous structure which adheres to the substrate and the sensing electrodes.
The drying and organic decomposition processes generally require temperatures up to ˜300° C. but the firing process requires higher temperatures. These temperatures are dependent on many variables such as the starting metal oxide material, the dopants and/or catalysts added to the materials, the metal oxide grain size, the film thickness and the required final structure and porosity. Generally these temperatures exceed 500° C. so care needs to be taken not to adversely affect the quality of the other materials in the sensor such as the substrate, the sensing electrodes and any interconnects.
The use of ceramic substrates generally alleviates some of these sensitivities to processing at elevated temperatures but the use of silicon substrates, particularly CMOS compatible silicon substrates causes some concern. For example, CMOS wirebond pads are generally Aluminum which will readily degrade at temperatures greater than about 400° C. which renders them unsuitable for wire-bonding or providing an Ohmic interconnect. Addition of CMOS circuits to the substrate for control, processing or memory functions are equally at risk to elevated temperatures.
Typical annealing processes using standard conduction and/or convection ovens compromises the final quality of the substrate and any circuits or interconnects contained therein.
Most MOX firing/heating is performed indiscriminately so is not CMOS compatible unless lower than optimum temperatures are deployed which results in compromised sensor quality and performance, as demonstrated in U.S. Pat. No. 8,669,131 B1.
To date various methods are deployed for selective heating such as laser annealing or built in heaters. Both of these methods are slow and costly so not suited to high volume manufacture.
Other methods involve the use of thin films such as CVD or sputtering which do not generally require a post firing process, as demonstrated in US 20110290003 A1.
For metal oxide processing it is possible to use flame spray pyrolysis which utilises a shadow mask to ensure selective deposition and simultaneous firing. This method prevents the user from making changes to the material properties such as porosity and grain size that are essential to produce a quality gas sensor. This method also relies on a shadow mask for selecting the deposition area as the deposition technique is indiscriminate and therefore wasteful of materials that can be very costly as they are likely to contain noble metal dopants and/or catalysts. This is demonstrated in US 20120094030 A1.
Conventional rapid thermal processing (RTP) has been used for firing ceramic films but does not leverage the advantage of selective area heating due to the process and structure used. This is demonstrated in WO 2010129411 A2.


This invention is for an accelerometer having a stack comprising both linearly responsive transducers and rotationally responsive transducers for measuring accelerations in the six degrees of freedom. Linear transducers such as lifters and tangenters can be combined in a stack with rotational transducers such as teeters and twisters which react to accelerations. Position sensors can be placed adjacent the transducers to sense their movement. When the position sensors detect a change, a current is applied to the transducer to return the transducer to its rest state. The current applied to return the transducer to its rest state is proportional to the acceleration experienced by the transducer, thereby providing a means to measure the acceleration on the transducer.

1. Field of the Invention
The present invention generally relates to accelerometers and more specifically to accelerometers with piezoelectric actuators.
2. Background Art
In the past piezoelectric actuator elements have been used in accelerometers. When the piezoelectric element is acted on by an acceleration, the force applied to the piezoelectric element strains the element and yields an electric current proportional to the force applied to the piezoelectric element. In some embodiments piezoelectric elements have been employed in conjunction with non-contact electron transfer effects to measure the distance between the piezoelectric element and an object. When such an instrument is accelerated the distance between the object and the piezoelectric element changes and is measured. The distance change is directly related to the acceleration. The displacements measured have until now been limited to linear accelerations of the piezoelectric elements. Angular accelerations were not possible to measure directly with piezoelectric elements since they were linearly polarized.