Low rate data and middle rate data are time division multiplexed independently according to their rates by a time division multiplexer so that their rates match the rate of high rate data which are not passed through the time division multiplexer. Subsequently, the entire data are converted into biorthogonal signals by biorthogonal signal generators (BORTs), and code division multiplexed by a code division multiplexer. The code division multiplexed signal undergoes modulation by a spreading modulator and a carrier modulator, and transmitted.

1. Field of the Invention
The present invention relates to a spread spectrum communication system.
2. Description of Related Art
Spread spectrum communications is a method in which the spectrum of an information signal is spread into much wider bandwidth by multiplying the information signal by a spreading code, thereby transmitting the information with much wider bandwidth than that of the original information signal, and has characteristics such as communication secrecy, anti-interference, anti-multipath fading, and multiple access capability. The term multiple access refers to a communication system in which a plurality of mobile stations communicate simultaneously with a base station. The performance of the spread spectrum communications depends on a spreading factor which is defined as a ratio of the bandwidth of transmission to that of the information signal, that is, a ratio of the rate of the spreading code to that of the information transmission. The spreading factor, represented in terms of dB, is called the processing gain. For example, if the rate of the information transmission is 10 kbps, and that of the spreading code is 1 Mcps, the spreading factor becomes 100, and the processing gain 20 dB.
The multiple access using the spread spectrum communications is termed CDMA (Code Division Multiple Access). In the CDMA system, each one of the users or channels uses a different spreading code so that they are distinguished by the spreading codes.
Although the CDMA system has been considered to be inferior to the other multiple access Systems such as TDMA (Time Division Multiple Access) in channel capacity (the number of channels in a particular bandwidth), Gilhousen, et al, report that it is superior to the TDMA system when applied to a cellular telephone system, as disclosed in Gilhousen et al, "On the Capacity of a Cellular CDMA Systems", IEEE Transactions on Vehicular Technology vol. 40, No. 2, May 1991.
FIG. 28 shows a transmitter of a base station in a cellular mobile communication system disclosed in the above-mentioned paper. To transmit information to a plurality of users at the same time, the base station makes a multiplexed signal from respective users' signals and then transmits them. In FIG. 28, the reference numerals 2801-280N denote digital processors of the signals to individual users (user #1-user #N) whose output signals are multiplexed and carrier modulated by a digital linear combiner and QPSK modulator 2810. Its output is fed to a transmitter 2811, and undergoes frequency conversion and power amplification to be transmitted to mobile stations. The QPSK (Quadrature Phase Shift Keying) is usually called quadrature digital phase modulation.
Although interference amounts between users are kept low in a CDMA system because of employing different spreading codes, the total interference amount increases with the number of users. The total interference amount and allowable received signal quality decide the channel capacity.
A base station can multiplex signals with each signal being synchronized. In this case, using orthogonal codes as spreading codes makes it possible to reduce to zero the interference among mobile stations receiving the signals transmitted from the same base station. Thus using the orthogonal codes enables the interference to be reduced, and is very preferable for the CDMA system, although transmitted signals from other base stations or multipath fading signals with different received timings even from the same base station cause interference between signals.
The conventional techniques described below use multiplex transmission employing orthogonal codes in the transmission from a base station to mobile stations except for the cases otherwise specified.
FIGS. 29 and 30 illustrate a multiplex transmission method of a base station disclosed in U.S. Pat. No. 5,103,459, for example. The apparatus shown in FIG. 29 corresponds to one of the transmitted signal digital processors 2801-280N as shown in FIG. 28, and the apparatus shown in FIG. 30 correspond to the linear combiner and QPSK modulator 2810 and the transmitter 2811 as shown in FIG. 28.
In FIG. 29, voice channel data 2901 is error correcting encoded by an error correcting encoder 2902, interleaved by an interleaver 2903, and then input to a data scrambler 2904. The data scrambler 2904 carries out exclusive OR operation between the input and another input, a PN code generated by a PN code generator 2905, thus being data scrambled. Since only the data scramble rather than spectrum spreading is intended here, the code rate of the PN code generated by the PN code generator 2905 is the same as the bit rate of the output of the interleaver 2903.
The output of the data scrambler 2904 is converted by an orthogonal encoder 2906 into orthogonal codes by using Walsh functions provided by a Walsh generator 2907. The Walsh functions are orthogonal code sequences generated on the basis of an Hadamard matrix, such that different Walsh functions are assigned to respective users. In the example as shown in FIG. 29, the orthogonal encoding is carried out at a code rate 64 times faster than the bit rate of the data output from the scrambler 2904.
The output of the orthogonal encoder 2906 is fed to two spread spectrum modulators (EXORs) 2908 and 2909 to be spectrum spread by different PN sequences generated by two PN code generators 2910 and 2911. The PN codes generated by the PN code generators 2910 and 2911 are common to the entire users, and are used to reduce interference between signals transmitted from different base stations. The rate of the PN codes are the same as that of the Walsh functions.
The output of the spread spectrum modulators 2908 and 2909 undergo waveform shaping (band limitation) by FIR (Finite Impulse Response) filters 2912 and 2913, gain adjusted by gain adjusters 2914 and 2915, and then input to the linear combiner and QPSK modulator as shown in FIG. 30. To the linear combiner and QPSK modulator, spread spectrum signals are fed which have been orthogonal encoded using orthogonal codes having the same structure with but different patterns from those as used in FIG. 29 (that is, Walsh functions of different numbers).
The orthogonal encoded spread spectrum signals are converted into analog signals by digital-to-analog (DA) converters 3011-30N2, and are input to an adder (.SIGMA.I) 3030 and an adder (.SIGMA.Q) 3031 to be added, respectively, thereby being output as multiplexed signals. The multiplexed signals are multiplied by two orthogonal carriers, sin(2.pi.ft) and cos(2.pi.ft), in multipliers 3032 and 3033, respectively, and then combined by an adder (.SIGMA.) 3034, thereby QPSK modulated.
In this case, since the same information of each user is halved to undergo the spectrum spreading by different PN code sequences and subsequently the QPSK modulation, the information modulation is BPSK modulation (binary PSK or binary digital phase modulation) and the spreading modulation is QPSK (quadrature digital phase modulation).
The QPSK modulated multiplexed signal is multiplied in a multiplexer 3035 by a sine wave provided from a frequency synthesizer, and the fundamental wave component of its output is extracted through a bandpass filter (BPF) 3036. The output of the filter is power amplified by an RF amplifier (RF AMP) 3037, and is led to an antenna.
In the CDMA system, larger channel capacity is achieved when the total interference power is reduced. In the voice communications, as there are soundless intervals, the channel capacity can be increased by an amount corresponding to suppression of information transmission during the soundless intervals.
In the example as shown in FIGS. 29 and 30, the rate of the voice encoders is permitted to be set at one of four steps (full rate, 1/2, 1/4 and 1/8) in response to the voice communication state so as to increase the channel capacity, and the transmission power is set in accordance with the rates. More that is, although each encoder outputs data at the same rate, it repeats the contents of the output by the number corresponding to the rates, so that the transmission power can be reduced in accordance with the number of repetition.
For example, since the number of bits per particular time period becomes 1/2 of the full rate when transmitted at 1/2 rate, the duration of the output from the encoder also becomes 1/2. Thus, the encoder repeats the same contents twice, and the transmission power is set at 1/2. Likewise, background noise is encoded at 1/8 rate during the soundless interval, so that the error correcting encoder continually outputs the same encoded data eight times, enabling the transmission to be carried out with the transmission power reduced to 1/8.
Thus, the example as shown in FIGS. 29 and 30 discloses a means for reducing generation of the interference by using the orthogonal codes with the signals transmitted from the same base station, or a means for reducing the transmission power by switching the information rate in response to the voice communication state. This system, however, is a low transmission rate system assuming a cellular telephone system, and hence the maximum rate of the voice channel data 2901 shown in FIG. 29 is limited to 9.6 kbps. Accordingly, other means are required to transmit higher rate data such as image or computer data rather than voice data.
FIG. 31 shows an apparatus for transmitting higher rate data disclosed in JP-T 5/506763, and corresponds to the apparatus shown in FIGS. 29 and 30. The apparatus shown in FIG. 31 differs from that shown in FIGS. 29 and 30 in that its controller 3101 keeps constant the spreading code rate, that is, the transmission bandwidth by optimally controlling the encoding factor of the error correcting encoder, interleave size, and the code length of the Walsh functions in response to the input data rate, thereby flexibly adjusting itself to various transmission rates. In JP-T 5/506763, Table I is shown as an example of the parameters of the controller 3101 of the encoding factor rate and the code length of the Walsh functions in accordance with the input data.
TABLE 1 ______________________________________ Spreading Input Total Walsh code rate data spreading Encoding function (M chips/s) rate(k bits/s) factor factor factor ______________________________________ 1.2288 9.6 128 2 64 1.2288 4.8 256 4 64 1.2288 19.2 64 2 32 1.2288 16 76.8 2.4 32 ______________________________________
In Table I, the spreading code rate is given as a product of the input data rate and the total spreading factor, where the spreading factor is the product of the encoding factor and the Walsh function factor. For example, in the case where the input data rate is 9.6 kbps, the error correcting code (convolutional code) with an encoding factor of two (=coding rate of 1/2) is used, the encoded symbol rate becomes 19.2 kbps (=9.6 kbps.times.2) after the error correcting encoding, and the spreading code rate becomes 1.2288M chips/s (=19.2 kbps.times.64) by multiplying each encoded bit by the Walsh function with a code length of 64. With the other transmission rates, they can be calculated in the same manner. Incidentally, the encoding factor means the ratio of the bit number of the output of the error correcting encoder to that of the input information. In other words, the encoding factor is the inverse number of the coding rate.
The above-mentioned setting method is expected to make optimum use of the available transmission band by utilizing the fact that the Walsh function factors have the powers of two owing to their structure, and the upper limit of the spreading code rate is limited to 1.2288M chips/s. This is achieved by adjusting the encoding factor and Walsh function factor when the input data rate is an integer multiple of 9.6 kbps, or by making the encoding factor different from the integer multiple and setting the Walsh function factor appropriately when the input data rate is not the integer multiple. To achieve this, a technique called punctured encoding is used for the encoding method in addition to the convolutional encoding.
Thus, the example as shown in FIG. 31 handles the increase in the transmission rate by varying the encoding factor and the Walsh function factor. A further increase in the transmission rate will require a decrease in the encoding factor or the Walsh function factor.
The decrease in the encoding factor, however, results in the reduction of the error correcting performance, and this will prevent the required transmission quality from being achieved. In the example as shown in FIG. 31, to achieve the transmission quality matching that of the data transmission of 9.6 kbps, the encoding factor of two or more is needed.
The reduction in the Walsh function factor, on the other hand, results in a decrease in the code length of PN-I and PN-Q to be multiplied, which in turn results in a decrease in the spreading factor (spreading code rate/data transmission rate), and this will reduce the characteristics of the spread spectrum communications such as multiple access, anti-jamming, anti-interference, thereby limiting its spreading factor. For example, Ryuji KOHNO et al. reported that the processing gain (that is, the spreading factor) was limited to about 100-1000, considering the multipath fading resistance and system uniformity, in Ryuji KOHNO, et al. "Spread Spectrum Access Methods for Wireless Communications", IEEE Communications Magazine, pp. 58-67, January 1995) (the upper limit is restricted by hardware implementation and frequency band assignment, and so on).
Thus, it is necessary to employ other measures to carry out communications at a data rate exceeding 19.2 kbps in the example as shown in FIG. 31. FIGS. 32-36 are diagrams showing CDMA systems capable of handling various services, which were disclosed in A. H. Aghvami, "FUTURE CDMA CELLULAR MOBILE SYSTEMS SUPPORTING MULTI-SERVICE OPERATION", 5th IEEE International Symposium on Personal Indoor and Mobile Radio Communication, 1994.
FIG. 32 is a diagram illustrating a method in which signals of various data rates, such as data, image and voice, are each spread over the entire assigned frequency band. In this case, since the data rates differ while the code rate of the spreading codes is identical, the processing gain (spreading factor) varies in accordance with the data rates. The spreading codes and the transmission power also depend on the transmission quality required.
When the data rates differ from each other in the CDMA system, energy per data bit is usually adopted as a criterion to equalize the transmission quality. For example, high rate data (computer data, for instance) demands larger power because of shorter data interval, and low rate data (voice, for instance) requires smaller power because of longer data interval. Although this method is simple, it still has a problem similar to that of the system as shown in FIG. 31 in that it reduces the characteristics of the CDMA because its spreading factor decreases with an increase of the data rate.
FIG. 33 illustrates a method in which the entire frequency band is divided into sub-bands of different widths so that low rate signals (voice) are assigned to a smaller sub-band, middle rate signals (video) are assigned to a larger sub-band, and a high rate signal is assigned to the entire band. The smaller sub-band and the larger sub-band are used separately or repeatedly.
Although this method has an advantage that the processing gain (spreading factor) can be set within a certain range when the transmission rate is below a particular value, it also has a problem in that it reduces the characteristics of the CDMA as the systems shown in FIGS. 31 and 32 because the spreading factor decreases when the transmission rate exceeds the particular value. Furthermore, since the low rate signals and the middle rate signals use different frequencies, a control mechanism for assigning the frequency is required in addition to multiple frequency generators. Moreover, it has a problem in that both the transmitter and receiver become larger because of a plurality of analog sections (filters, for example) for matching various transmission bands corresponding to the rates.
FIG. 34 illustrates a method in which a time frame is divided into sub-slots of different length so that low rate signals (voice) are assigned to a smaller time slot, and middle rate signals (video) are assigned to a larger time slot, and a high rate signal is assigned to the entire time slot, thus using the time slots separately or repeatedly.
Although this method also has an advantage that the processing gain (spreading factor) can be set within a certain range when the transmission rate is below a particular value, it also has a problem in that it reduces the characteristics of the CDMA as the systems shown in FIGS. 31, 32 and 33 because the spreading factor decreases when the transmission rate exceeds the particular value.
Furthermore, since the data interval reduces with the spreading factor as the transmission rate increases in the methods shown in FIGS. 32-34, the discrimination performance is lost for delay waves with a delay corresponding to the data interval when periodic spreading codes are used. This presents a new problem in that it causes co-channel interference.
FIG. 35 illustrates a multicode system in which a plurality of spreading codes are assigned to middle rate signals and high rate signals. The middle rate signals and high rate signals undergo serial-to-parallel conversion in accordance with their rates so that resultant low rate signals are multiplexed after orthogonal encoded using orthogonal codes. This enables the various rate data to be spread at the same spreading factor, thereby providing measures against the reduction in the processing gain (spreading factor) and co-channel interference, the problems involved in the methods as shown in FIGS. 32-34. The variation in the amplitude due to the multiplexing can be solved by spreading the data using PN codes, after obtaining binary sequences from multilevel signal using a multi-values to binary conversion. The Aghvami paper discloses the application of orthogonal modulation, in which one of orthogonal codes like Walsh functions is selected, for the multilevel binary conversion (or for the multi-values to binary conversion).
The multilevel binary conversion, however, has a problem in that the frequency efficiency rapidly reduces with an increase of the multiplexed number. The reason for this is as follows. The code length of the orthogonal functions are given by 2.sup.N, where N is the multiplexed number. Accordingly, when the transmission is carried out under the same processing gain (spreading factor) and the same spreading code rate, the bandwidth increases by a factor of 2.sup.N as compared with the transmission using multi-valued levels.
In addition, a normal multilevel binary conversion without using the orthogonal modulation usually performs parallel-to-serial conversion, which demands N times the bandwidth as compared with the transmission using the multivalued levels as long as the processing gain (spreading factor) and the spreading code rate are fixed. Thus, the problem of the frequency efficiency reduction remains unsolved.
FIG. 36 illustrates a method combining the methods as shown in FIGS. 32-35. This method combines the systems as shown in FIGS. 32-35 in accordance with services offered or the propagation environment of electromagnetic waves. Although this method makes it possible to take optimum measures depending on the state of voice, image, or data, it has a problem in that the system control becomes exceedingly complicated, and assigning control becomes complex.
FIGS. 37-40 illustrate optimum systems of spectrum using, which are disclosed in JP-A 7/303090, in which the spectrum is optimized for high rate users (A, B, G and L), middle rate users (C, E, F, H, I, J, M, O and Q) and low rate users (D, K, N, P, R, S and T).
The method as shown in FIG. 37 assigns slot numbers and code numbers to users with different rates. It differs from the method as shown in FIG. 34 in that it assigns a plurality of spreading codes besides the slot numbers. The method as shown in FIG. 37 enables the high rate transmission to carry out the multicode transmission to keep the processing gain (spreading factor) greater than a fixed value. The method, however, has a problem in that the system becomes complicated. For example, although user F can obtain the desired processing gain (spreading factor) by using only a single code, it actually performs transmission using multicodes consisting of three codes C0, C1 and C3. This requires the receiver to prepare a plurality of correlators, thereby making the system complicated.
The method as shown in FIG. 38 assigns sub-frequency bands and codes to users of different rates, that is, to high rate users (A, B, G and L), middle rate users (C, E, F, H, I, J, M, O and Q) and low rate users (D, K, N, P, R, S and T). It differs from the method as shown in FIG. 33 in that it assigns a plurality of spreading codes besides the subfrequency bands. The method as shown in FIG. 38 enables the high rate transmission to carry out the multicode transmission to keep the processing gain (spreading factor) greater than a fixed value. This method, however, has a problem in that the system becomes complicated. For example, although user F can obtain the desired processing gain (spreading factor) by using only a single code, it performs transmission using multicodes consisting of three codes C0, C1 and C3. This requires the receiver to prepare a plurality of correlators, thereby making the system complicated. Furthermore, it has another problem in that complicated control must be performed such as frequency assignment and code assignment. Moreover, it has a problem in that both the transmitter and receiver become large because a plurality of analog sections must be prepared which include multiple transmission bands and frequency synthesizers corresponding to a plurality of transmitting and receiving frequencies and frequency bands.
The method as shown in FIG. 39 assigns both slots and codes to users of different rates, that is, to high rate users (A, B, G and L), middle rate users (C, E, F, H, I, J, M, O and Q) and low rate users (D, K, N, P, R, S and T). The codes are not multicodes but single codes with different code lengths. The high rate users can achieve high rate transmission by occupying a small code C5 over a long time period in the code space as denoted by A in this figure, or by occupying a large code G for a short time in the code space as denoted by G in this figure.
The method as shown in FIG. 39 assigns only one code to each user, thus allowing the receiver to prepare only one correlator for each corresponding code. It is necessary for the receiver, however, to increase the code rate when a large code space is assigned, and this requires the receiver to prepare a plurality of spreading code generators and correlators so that it can cope with the code rate corresponding to the large code space. Furthermore, either analog sections including a plurality of transmission bands must be prepared, or wideband filters must be prepared allowing the degradation of characteristics. The former presents a problem in that the size of the transmitter and receiver increases, and the latter has a problem in that the transmission quality is degraded.
FIG. 40 shows a method in which the slots, frequencies and codes as shown in FIGS. 38 and 39 are combined to achieve optimum results with the users of different rates, that is, high rate users (F, G and H), middle rate users (A, B, C and E) and low rate users (D, H, I, K and L). This method has an advantage that the frequency, time and code space can be efficiently utilized. The method, however, has a problem in that complicated control is required to assign the frequency, time and codes. In addition, since it is necessary for both the transmitter and receiver to prepare a plurality of correlators corresponding to the multiple codes, and analog sections corresponding to the plurality of transmission bands, a new problem arises that the circuit scale increases.
The methods as shown in FIGS. 37 and 38 do not take steps for the multivalued signal levels due to multicode multiplexing. Accordingly, the demand grows severe for linearity of the power amplifier used in the transmitter in accordance with the multivalues of the signal levels. This presents a further problem in that this prevents a reduction of a circuit size and a power consumption of a circuit.
Generally speaking, the number of simultaneously communicatable channels is less than that of assignable channels (that is, the number of codes). This is because the multiplex transmission from a base station to mobile stations using orthogonal codes is subjected to interference due to multipath fading and base stations of neighboring cells, and such interference increases with the number of multiplexed channels, and hence an required error rate comes to be unachievable. The reverse link transmission from mobile stations to the base station has greater interference than the forward link transmission from the base station to the mobile stations because it is difficult for the mobile stations to synchronize transmission timings among them.
In the foregoing paper of Gilhousen et al, "On the Capacity of a Cellular CDMA Systems", IEEE Transactions on Vehicular Technology vol. 40, No. 2, May 1991, Gilhousen et al. reports that although the number of assignable channels to the base station is 64 in the system as shown in FIGS. 29 and 30, the number of simultaneously communicatable channels falls about 36. The number is an ideal one considering channel the increasing effect of channels due to reduction of rates in response to the state of voices, and assuming the best conditions of transmission power control and sectoring gain, and therefore the actual number of simultaneously communicatable channels is further reduced. In other words, the actual number of practically usable channels will be reduce to only about half the assignable channels. This is true with the conventional methods of FIGS. 31-40.
One possible method to make effective use of the assignable channels would be to limit the multiplexed number (Walsh function factor) to 32 out of 64 as shown in the following Table 2, and to increase the error correcting power of the error correcting codes. This method corresponds to set the encoding factor at a high value.
TABLE 2 ______________________________________ Input Spreading data Total Walsh code rate rate spreading Encoding function (M chips/s) (k bits/s) factor factor factor ______________________________________ 1.2288 9.6 128 4 32 ______________________________________
Although adopting such a method will increase the communication quality because of the improved error correcting performance, it presents a problem in that the amount of processing involved in decoding becomes enormous, and the scale of hardware increases. More that is, when adopting convolutional codes as the error correcting codes as already described in connection with the conventional techniques, Viterbi decoding is often employed as a decoding method, whose processing amount depends on the encoding factor 1/r and the constraint length K, and is proportional to (1/r).sup.K, where r is the encoding rate. Thus, if the encoding factor is doubled from two to four for example, the processing amount is increased from 2.sup.K to 4.sup.K. As for the constraint length K, the conventional techniques usually use a value from seven to nine, and hence the processing amount of decoding increases in proportion to 2.sup.7 or 4.sup.7.
In addition, it is preferable to take some steps for carrying out multi-valued levels of signals due to multicode multiplexing.
FIG. 41 is a system block diagram of a parallel combination system proposed in "Consideration on Soft Decision Viterbi Decoding Characteristics under Multipath Rayleigh Fading in PC-CDMA (Parallel Combination Code Division Multiplex Access)" by Katsura, et al, Technical Report of the Institute of Electronics, Information and Communication Engineers of Japan SST95-58 (1995-09), pp. 79-83.
In FIG. 41, the information data undergoes the error correcting encoding by convolutional codes with a rate of 1/2, followed by the interleaver, and is divided in parallel into 128 encoded) bits. The 128 encoded bits undergo multicode multiplexed transmission by every four encoded bits in 32 groups. The orthogonal codes for multicode multiplexing are called orthogonal Gold codes and prepared total of 256. However, since the multiplexed number is 32, the 256 orthogonal Gold codes are divided into 32 groups each consisting of eight Gold codes, one of which is selected from each group. The code to be selected is decided by the four encoded bits. That is, three encoded bits decides which one of the eight orthogonal codes is to be selected, and the remaining one bit decides the polarity of the selected orthogonal code. The orthogonal Gold codes are described in Shu et al. "On Nonlinear Binary Spreading Sequences", pp. 37-42 of Technical Report of the Institute of Electronics, Information and Communication Engineers of Japan, IT90-7, May 1990.
At the receiving side, the four encoded bits per group can be decoded by detecting which code is transmitted in which polarity. In the case, it is necessary for the receiver to perform coherent detection to detect the polarity. The system as shown in FIG. 41 effectively carries out the coherent detection by simultaneously transmitting multiplexing orthogonal codes for a pilot channel, and by extracting the carrier phase by demodulating the pilot channel at the receiving side.
This method is called biorthogonal signal transmission method, and its characteristics were reported in M. Yokoyama, "Spread Spectrum Communication System", 1988, Science and Technology Publishing Company Inc. in Japan. The biorthogonal signal transmission method has an advantage of reducing the error rate over the common signal transmission method. In addition, it provides an advantage of mitigating the requirement for the linearity of an amplifier because the multiplexed number is reduced to 1/4 since one orthogonal code corresponds to four encoding bits.
The system as shown in FIG. 41, however, has a problem in that the size of both the transmitter and receiver is increased because the transmitter must prepare the entire orthogonal codes, and the receiver must calculate the correlations between the entire orthogonal codes and the received signal. In addition, it lacks flexibility with low rate transmission whose bit number differs from an integer multiple of the four encoding bits. Furthermore, since the receiver must be provided with individual correlators for respective channels as the rate of data increases, thereby increasing a hardware scale of or a circuit size of a communication system.


A device for folding sheets of paper for placement in envelopes. The device has a center planar member and two side planar members connected with hinges so that the two side members can be rotated over the center member. A laminar member with beveled edges and coextensive with the center member is attached to the center member in such a way that a sheet of paper can be inserted between them so that it extends in part beyond the center member to each side members. The user rotates each side member in turn over the center member, thereby enabling the laminar member to crease the paper. Indicator lines on one of the side members allows the alignment of the paper with respect to the laminar member so that creases are made in desired locations.

1. Field of the Invention
The present invention relates to folding sheets of stationery or other papers. In particular, the present invention relates to a device for evenly folding sheets of paper to fit into envelopes.
2. Discussion of Background
Sheets of paper are available in many different sizes, including the familiar 8.5".times.11" (about 21.6.times.27.9 cm), 8.5".times.14" (about 21.6.times.35.6 cm), and A4 metric (21.times.30 cm; about 8.3".times.11.8") standard sizes. Envelopes are also available in different sizes. Some envelopes are dimensioned to accept standard size paper without folding; most envelopes, however, require folding the paper approximately into halves, thirds, or fourths for insertion therein. A commonly-used envelope is dimensioned to accept standard letter-size paper folded into thirds. By "folded into thirds" it is meant that the paper has two creases running parallel to the shorter side and dividing the sheet into three, roughly equal sections.
Paper is preferably folded so that the creases are sharp, parallel to the sides of the paper and spaced so that the folded paper just fits into the chosen envelope. Folding paper by hand does not always result in sufficient precision; the creases may not be parallel to the sides and one section of the folded paper may be too large, perhaps too large to fit into its envelope. Accordingly, envelopes for business use have a little margin to accommodate a slightly misfolded sheet.
Applicant is unaware of devices for folding sheets of stationery into evenly-spaced divisions for placement in envelopes.


Provided is a technique for improving banknote manageability in a banknote handling device. This banknote handling device is provided with multiple banknote storage compartments where banknotes are stored, and a banknote loading compartment where banknotes are stored that are to be loaded in each of the banknote storage compartments. This banknote handling device is provided with a banknote determination unit which obtains the serial numbers of banknotes in conveyance between the banknote storage compartments and the banknote loading compartment, and a conveyance path which conveys banknotes from the banknote loading compartment to the banknote storage compartments via the banknote determination unit. A main control unit of the banknote handling device controls the conveyance path, and, while loading the banknotes from the banknote loading compartment into each of the banknote storage compartments, performs banknote loading processing in which the serial numbers of the banknotes are obtained from the banknote determination unit.

In a financial institution, a banknote handling device is used at the time of transaction involving payment and receipt of money between a customer and a staff (a so-called teller) of the financial institution (for example, JP-A-2004-145600). Here, in case of deposit transaction at the financial institution, it is generally treated that the customer side has the ownership of banknotes until the transaction is established. Therefore, the banknote handling device adopts a structure that even after the reception of the banknotes from the customer in the deposit transaction, the banknotes are stored in a temporary holding unit to keep them returnable until the transaction is established, and after the transaction is established, the banknotes are stored in the storage compartments by denomination. The banknote handling device also has a function to exclude as a reject banknote a banknote having a stain, a shape or the like not satisfying a prescribed standard and not suitable for transaction, from the transaction object in order to perform the banknote transaction smoothly.


A laboratory centrifuge includes two rotating parts (10, 11) associated by translation locking elements (13) including at least one female element (16) and at least one complementary male element (15). The male element (15) is associated with elements (20) for its operation to the inactive position, which include a rotating actuator member (21) carried by one of the rotating parts (11) and which cooperates with the male element (15) to ensure, by a rotational operation of the rotating actuator member (21) about its axis of rotation (21′), the displacement of the associated male element (15) from the active position to the inactive position.

Centrifugation allows to separate components of very variable size and mass contained in a liquid sample, from molecules to entire cells.
Such centrifugation techniques are conventionally implemented by means of laboratory centrifuges that comprise a chamber containing two rotating parts, i.e.:                a driving motor shaft, associated to motor means for the rotational operation thereof, and        a rotor, intended to be mounted on said motor shaft and intended to receive the containers in which are provided the liquid samples to be centrifuged.
Conventionally, these two rotating parts are provided with complementary assembly means, for removably mounting the rotor on the free end of the driving motor shaft.
These assembly means comprise in particular means for locking in translation the two rotating parts associated to each other.
For example, in the document FR-2 951 964, these translation locking means comprise two male elements carried by the rotor, which are liable to occupy a position of cooperation with a female element arranged on the driving motor shaft.
These two male elements are each pivotally mounted about an axis of rotation extending parallel to a central longitudinal axis.
The rotor is mounted on the motor shaft by being simply fitted thereto, the male elements being retracted by being pushed by the rotor before being automatically locked in the active position within the above-mentioned female element.
To separate the rotor from the driving shaft, the operator must press simultaneously on two protruding lugs, diametrically opposed to each other, which are each carried by one of the pivoting male elements.
This action allows to operate the male elements to an inactive position, which corresponds to their separation from the female element, so as to make possible the translation of the rotor with respect to the driving motor shaft.
But, in practice, pressing on these lugs is not always easy and is not much ergonomic. It is indeed often necessary to exert a relatively high force to obtain the displacement of these lugs, and this with only the end of the fingers. Furthermore, the operation of these lugs requires a precise positioning of the fingers, which forces the operator to verify their orientation before manipulating them.
The operator must also displace entirely the two lugs; the differences of feeling when manipulating one and/or the other of these lugs might disturb the user, up to make him/her have doubts about the operation thereof between the locked and unlocked positions.
Such lugs are moreover liable to generate an aerodynamic noise; they are also relatively complex to clean, as the locking means are relatively open.

Laboratory centrifuge with locking system for locking in translation of rotor on driving motor shaft


To provide a fuel cell power generator capable of reliably recognizing ignition and misfire of a burner for heating a fuel gas generator and operating safely, a fuel cell power generator comprising, a fuel gas generator for generating a fuel gas composed mainly of hydrogen from a raw material for power generation and water, a water feeder for feeding water to the fuel gas generator, and a fuel cell for performing power generation using the fuel gas and oxidant gas is provided with: a burner for heating the fuel gas generator by combusting at least one combustion fuel selected from the group consisting of the raw material for power generation, the fuel gas, and an off-gas discharged from a fuel cell; and a flame detector for detecting the state of a flame formed in the burner.

A prior art power generator using a fuel cell is described below with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing the configuration of a prior art fuel cell power generator. FIG. 4 is a diagram showing the configuration of a control circuit of the prior art fuel cell power generator. In a fuel cell 1 shown in FIG. 3, an air electrode 2 and a fuel electrode 3 are arranged such as to sandwich a polymer electrolyte membrane 4, and the upstream side of the air electrode 2 is connected to a blower 5 for supplying air. A hydrogen generator (fuel gas generator) 6 is supplied with a power generation fuel X serving as a raw material such as natural gas or methanol and water Y necessary for a steam reforming reaction, and the obtained fuel gas G is supplied through a switching valve 7 to the fuel electrode 3, and thereby flows downstream through a predetermined passage contacting with the fuel electrode 3. At that time, a required amount of hydrogen in the fuel gas G is consumed in an electrode reaction, whereby the residual hydrogen and the like are supplied as off-gas OG to a burner 8. When the fuel gas G is not supplied to the fuel electrode 3, the fuel gas G is supplied through the switching valve 7 to the burner 8.
In general, when the fuel cell power generator is in the off state, the passages for the fuel gas G and the off-gas OG in the fuel gas generator 6, the fuel electrode 3, and the like are filled with an inert gas such as nitrogen. Further, even when the fuel cell power generator is started up, until the temperature of the fuel gas generator 6 becomes stable, the concentration of carbon monoxide in the fuel gas G is high. The carbon monoxide degrades an electrode catalyst in the polymer electrolyte membrane 4 of the fuel cell 1 and, accordingly, the fuel gas G having a high carbon monoxide concentration is not allowed to go to the fuel cell 1 and is supplied through the switching valve 7 to the burner 8 for a few tens minutes to a few hours after the start up. When the time of a few tens minutes to a few hours has been elapsed after the start up and the temperature of the fuel gas generator 6 has become stable, the fuel gas G is supplied through the switching valve 7 to the fuel electrode 3 for starting power generation of the fuel cell 1.
The fuel gas G supplied to the burner 8 or the off-gas OG combusts with air supplied from a fan 9 to form a flame 11 in a combustion chamber 10, whereby the combusted gas heats the fuel gas generator 6. The flame 11 in the combustion chamber 10 is detected on the basis of the ion current, which is generated when a predetermined voltage is applied on the flame.
As shown in FIG. 4, a flame detector 12 is comprised of: a DC power supply 14 for applying a predetermined voltage on the electric conductor 13 and the burner 8 while using the flame 11 as a flame resister; a resistor (RA) 15 for converting a current (IRA) equivalent to the ion current (IF) flowing through the flame 11, into a voltage; a voltage detection section 16 for detecting the voltage across the resistor (RA) 15; and a control section (not shown) for controlling them, in order to measure the ion current which flows to the burner 8 via a heat resistive electric conductor 13 provided such as to contact with the flame 11.
As shown in FIG. 4, the control section (control circuit) of the flame detector 12 forms a current mirror circuit is formed by: transistors (Q1) 17 and (Q2) 18 each having the same characteristics; and resistors (R1) 19 and (R2) 20 each having the same resistance, in order to let a current (IRA) equivalent to the ion current (IF) flowing through the flame resistor (RF) flow through the flame resistor (RA) 15. Accordingly, currents (IR1) and (IR2) flowing respectively through the resistors (R1) 19 and (R2) 20 are equal to each other and a current equal to the currents (IR1) and (IR2) flows as the current (IRA) equivalent to the ion current (IF) flowing through the flame 11 to generate a voltage across the resistor (RA) 15. As such, the flame detection section 12 detects the combustion state such as ignition and misfire of the flame 11.
In such a prior art fuel cell power generator, the concentrations of hydrocarbon in the fuel gas G and the off-gas OG are extremely low because the hydrocarbon in the raw material for power generation X is converted into hydrogen by the steam reforming reaction. When the concentration of hydrocarbon is low, the ion concentration also becomes low in the flame 11, the current value flowing through the flame 11 is reduced and, hence, the voltage across the resistor (RA) 15 is reduced. That is, there has been the problem that the detection voltage in the flame detection section 12 becomes low to cause a difficulty in state recognition at the times of ignition and misfire. For example, when misfire is erroneously determined as ignition and the fuel gas is supplied continuously, under the condition that the combustion section is at a high temperature (400° C. or higher), there is a danger of explosive ignition when the concentration reaches the limit of explosion or higher. In contrast, when ignition is erroneously determined as misfire, such an unnecessary determination of misfire may cause a defect such as stoppage of the equipment operation.
Thus, in order to resolve the above-mentioned problems in the prior art, an object of the invention is to provide a fuel cell power generator capable of reliably recognizing ignition and misfire of a burner for heating a fuel gas generator and operating safely.

Matsushita Electric Industrial Co., Ltd.


A method of forming a toner image employing a photoreceptor is described. The photoreceptor comprises a photosensitive layer on a cylindrical conductive substrate, Formula (1) and Formula (2) are held,0<Pmax<2P  Formula (1)2≦(Pmax/D)×100≦50  Formula (2)wherein P (μm) is the average of the coating layer thickness in central section in the width direction of the photoreceptor, Pmax (μm) is average of the image forming region, and D (μm) is average of distance between point, at which said maximum value is obtained, and edge of the coating layer.

When a cylindrical electrophotographic photoreceptor (hereinafter occasionally referred to as a photoreceptor drum) is produced, a coating layer is generally formed by immersing a conductive cylindrical substrate into into a photosensitive layer composition or coating compositions for an interlayer and a surface protective layer.
In such a case, since the conductive cylindrical substrate is immersed into a coating composition, a coating layer is formed on the entire surface of the conductive cylindrical body. When a photoreceptor drum, which is subjected to formation of the coating layer on the entire surface, is mounted on an electrophotographic image forming apparatus, occasionally, it becomes impossible to accurately carry out hitting due to peeling of the coating layer through contact with rollers which hits development units. Further, occasionally, it becomes impossible to use the photoreceptor drum as a contact point for grounding. As a result, it is preferable to remove the coating layer adhered on both edges of the photoreceptor drum.
Methods for removing such a coating layer include a method in which edges of a photoreceptor drum are immersed in a solvent and is subjected to vibration employing ultrasonic waves (Japanese Patent Application Open to Public Inspection No. 63-311357), a rubbing method employing a brush (Japanese Patent Application Open to Public Inspection Nos. 3-60782, 4-141663, 5-142789, 10-207084, 11-184100, and 11-194509), and in addition, a removing method employing tape.
For example, a method (Japanese Patent Application Open to Public Inspection No. 6-138670) is known in which tape which is comprised of thermally fusible type nonwoven fabric is successively unwound, and the resulting tape is impregnated with solvent and thereafter, the impregnated tape comes into contact with a photoreceptor drum, thereby the removal is carried out. A method (Japanese Patent Application Open to Public Inspection No. 9-281725) is also known in which tape comprised of nonwoven fabric, having an uneven structure on one surface, is employed.
Based on the investigations performed by the inventors of the present invention, however, in any methods, the following problems were found. Edges of the coating layer of a photoreceptor drum, in which the coating layer had been removed, tended to peel off. Insufficient cleaning occurred due to accumulation of toner at the edges in which the coating layer had been removed and toner scattering occurred, resulting in staining of the interior of the apparatus. Due to those, durability of the photoreceptor drum as well as cleaning member (such as cleaning means) degrades. As a result, it has been demanded that edges of the coating layer are shaped so that such problems do not occur.
Current electrophotographic image forming apparatuses, which are widely employed on the market, comprise at least charging, image exposure, development, transfer and cleaning means as well as a fixing means at the periphery of the electrophotographic photoreceptor as an image bearing body.
A charging member, which has been employed as a representative member for the aforesaid charging means, is a corona discharge unit. The corona charging unit exhibits advantages in which stable charging is carried out. However, since it is necessary to apply high voltage to the corona discharge unit, a large amount of ionized oxygen, ozone, moisture, and oxidized nitrogen compounds is generated. As a result, electrophotographic photoreceptors are degraded and human body may be advisedly affected.
Therefore, currently, it has been investigated to utilize a contact charging system instead of using the corona discharge unit. Specifically, a magnetic brush or a conductive roller is subjected to voltage application and subsequently comes into contact with a photoreceptor which is a charging body, whereby the photoreceptor surface is charged to the specified electric potential. When such a contact charging system is employed, it is possible to decrease voltage as well as an ozone generation amount, compared to the non-contact type charging system employing the corona discharge unit.
Accordingly, the contact charging units, which decrease the amount of ozone generation, have been increasingly employed. However, since the photoreceptor surface is subjected to abrasion, during repeated image formation, the photosensitive layer is abraded, whereby excessive rubbing as well as peeling at the edges of the coating layer occurs.
Particularly, during the repeated use at high temperature and high humidity, toner is adhere-accumulated at the edges of the photoreceptor, whereby the torque between the cleaning blade and the photoreceptor varies, resulting in peeling of the coating layer at edges. Particularly, when peeling occurs, or coagulated toner which adheres to the aforesaid portion is mixed with developer as foreign matter, insufficient charging as well as insufficient cleaning results in black spots, whereby image quality is occasionally degraded.
Particularly, in recent years, in order to utilize excellent image quality which is an advantage of the electrophotographic image forming method, and to further improve the image quality, development toner, comprised of smaller size particles with uniform shape, has been commonly employed. In such cases, the aforesaid problems are more pronounced.

Image forming method, image forming apparatus, and processing cartridge


A method of modifying programs and databases having abbreviated date fields to achieve year 2000 compliancy includes examining an original database to ascertain the location of date fields, creating a supplementary PALM file that includes fully expanded date fields representative of corresponding date fields in the original database and modifying instructions or modules of the original program to access the PALM file for date information instead of the original database. The PALM file contains fully expanded date representations of abbreviated date fields of the original database. The PALM file also includes record identifiers and field identifiers to enable the modified program to access the required date information. Portions of the program requiring modification are identified by scanning for keywords that are generated from an examination of the database and/or from field layout definitions. The program is also examined for related keyword constructs or redefinitions found in the program itself. When converted, the modified program accesses the PALM file for date processing and accesses the original database for other processing steps. Further, a representative database having expanded date entries may be created based on examining a sample of an original database, and used by a modified legacy program to attain year 2000 compliancy.

The approaching millennium presents a challenge to the continued use and viability of existing programs and database systems. Despite introduction of more recent computing systems, these so called "legacy" systems continue to perform valuable functions and, as such, users continue to invest significant time and resources to maintain them. One reason is to avoid the great expense, inconvenience or disruption encountered to obtain suitable replacement.
Continued use of legacy systems beyond the year 2000 presents a particular problem. Many data and software structures of these older programs use abbreviated date fields, that is, date fields consisting of six characters to represent day/month/year, instead of the eight characters found in a non-abbreviated date field of more recent software systems that reflect the century. For example, the date Nov. 17, 1972 is designated as 11/17/1972 in a non-abbreviated date field format such as MM/DD/YYYY. By contrast, that date in an abbreviated format of MM/DD/YY would be 11/17/72, i.e., without designation of century. In other words, typical legacy systems experiencing the "year 2000 dilemma" are those in which two instead of four characters represent the year.
In calculating periods between respective dates in abbreviated formats, non-compliant systems simply subtract the earlier date from the later date to yield a result. For instance, in determining the number of years between 1949 and the year 1988, "49" is subtracted from "88" to correctly yield "39" years. A correct result is obtained so long as the year elements involved in the calculation represent the same century. Ambiguities arise when the calculation involves data elements of different centuries, such as, when determining the period between 1988 and 2002. The absolute value of subtracting abbreviated elements """88""" and "02" erroneously yield "86" years, instead of 14 years. Programs using such algorithms are said to be "non-compliant" with the year 2000.
One solution for "fixing" non-compliant programs, known as "expansion," involves altering date fields of a database by expanding their two-character year fields to four characters to indicate the century. In this way, subtracting "1988" from "2002" correctly yields "14" years. In addition, expansion of date fields often engenders compatibility problems due to a change in record size. In particular, the required recompilation of affected routines in the computing system relative to the "expanded" database segment may affect the ability of other routines that access the same database. Accordingly, expansion places a tremendous burden of conversion of the entire system, or necessitates the development of software bridges to enable communication between compliant and non-compliant portions of the computing system. Re-writing code to convert programs is time-consuming due to debugging and testing requirements. In some instances, it may also require a substantial amount of downtime. Developing software bridges is also time and labor intensive, requiring massive testing and increased processing time.
"Windowing" is another solution to attaining year 2000 compliance. It is less costly and involves identifying the century prefix for a date field assuming a fixed period of time typically, 20 to 50 years, before performing any calculation. This technique has limited applications and, at best, is only a temporary fix since it may disturb other algorithms in the computing system. Establishing a "19" or "20" century prefix by windowing requires establishing a predetermined time window based on a presumption that the values of date elements fall within a predetermined window. However, "windowing" is not reliable because it is based on information that is not constant as years pass, causing the need to redefine the window from time-to-time.
In view of the foregoing, it is therefore an objective of the present invention to provide an improved method and system for enhancing computer programs and databases to achieve year 2000 compliancy.
It is a further objective of the present invention to provide an automated process of modifying or enhancing computational systems for achieving year 2000 compliancy, thereby lessening the time, cost and manpower effort.
It is a further objective of the present invention to minimize the disruption of converting computational systems for achieving year 2000 compliancy that would otherwise be experienced using expansion or windowing techniques.
It is yet a further objective of the present invention to maintain system wide database integrity of computational systems by preserving the original database and yet still achieve the accuracy of expansion techniques.
It is yet a further objective of the present invention to provide a process of examining source code and databases for determining whether, and how much, they must be enhanced to achieve year 2000 compliancy.
It is another objective of the present invention to provide an auxiliary file for processing or handling date information externally of and without disturbing the original database, and to provide a method for scanning, searching and identifying date fields within a database for creating the auxiliary file.

System for converting programs and databases to correct year 2000 processing errors


The various technologies presented herein relate to the generation of x-rays and other charged particles. A plurality of disparate source materials can be combined on an array to facilitate fabrication of co-located mixed tips (point sources) which can be utilized to form a polychromatic cloud, e.g., a plurality of x-rays having a range of energies and or wavelengths, etc. The tips can be formed such that the x-rays are emitted in a direction different to other charged particles to facilitate clean x-ray sourcing. Particles, such as protons, can be directionally emitted to facilitate generation of neutrons at a secondary target. The various particles can be generated by interaction of a laser irradiating the array of tips. The tips can be incorporated into a plurality of 3D conical targets, the conical target sidewall(s) can be utilized to microfocus a portion of a laser beam onto the tip material.

Advances in laser technologies have enabled construction of laser sources which can be utilized in high energy physics applications. A laser beam can irradiate a target to facilitate generation of x-rays and other particles such as electrons, protons, photons, neutrons, etc., where such particle emissions can be utilized in applications such as radiography, airport security, crystallography, astronomy, spectroscopy, etc. While x-rays can identify high atomic number (high Z) materials such as stainless steel, neutrons can be utilized to identify low Z material such as polystyrene foams, wood, water. It can be beneficial to have a mixed source of x-rays and other particles which, when irradiated by a laser beam, can facilitate identification of both high Z and low Z materials.
While neutrons can be produced by a laser-target approach, neutrons can also be produced by Dense Plasma Focus machine (DPF). DPF typically produce neutrons of 2.45 MeV (when using deuterium-deuterium) or 14.1 MeV (when using deuterium-tritium). The maximum neutron energy is thus limited to 14 MeV. The neutron emission is typically isotropic, and requires use of tritium which is radioactive, and difficult to obtain and store. A conventional laser-target approach can generate neutrons having energies>15 MeV, can be energy tunable in a more continuous way. It can also allow for a broader energy spectrum of the neutrons produced and thus allows for applications such as resonance radiography. However the laser can be costly owing to the requirement to operate with a beam intensity exceeding 1×1018 W/cm2.

3D target array for pulsed multi-sourced radiography


A process for reducing the residual content of free alkylating agent in aqueous solutions of amphoteric or zwitterionic surface-active agents by aftertreatment with ammonia, an amino acid containing 2 to 8 carbon atoms, or an oligopeptide.

1. Field of the Invention
This invention relates to a process for reducing the residual content of free alkylating agent in aqueous solutions of amphoteric or zwitterionic surfactants by aftertreatment of the solutions with ammonia, an amino acid containing 2 to 8 carbon atoms or an oligopeptide.
2. discussion of Related Art
Amphoteric and zwitterionic surfactants are characterized by a molecular structure which contains two functional groups of different polarity, generally a cationic ammonium group and an anionic carboxylate or sulfonate function. Surfactants having an amphoteric or zwitterionic structure combine excellent cleaning power with good dermatological compatibility. In addition, since they form a dense stable foam in aqueous solution which does not collapse even in the presence of soap, these classes of surfactants represent valuable raw materials for the production of personal hygiene preparations, particularly hair shampoos and shower baths.
Amphoteric or zwitterionic surfactacts are synthesized from primary, secondary or tertiary amino compounds which are reacted with a suitable alkylating agent [J. Falbe (ed.), "Surfactants in Consumer Products", Springer Verlag, Berlin/Heidelberg, 1987, pages 114 et seq.].
Thus, alkyl betaines or alkyl amidobetaines of amphoteric structure are obtained, for example, from the quaternization of tertiary amines [Seifen-Ole-Fette-Wachse, 108, 373 (1982)]or fatty acid amidoamines [Parf. Kosm. Arom. 75, 67 (1968)]with halocarboxylic acids. Zwitterionic surfactants based on alkyl imidazolines which are alkylated with halocarboxylic acids [DE 36 39 752 A1] or acrylic acid [Seifen-Ole-Fette-Wachse, 109, 20 (1983)] are of particular commercial significance. By contrast, the reaction of tertiary amines with 3-chloro-2-hydroxypropane sulfonic acid to amphoteric surfactants of the sulfobetaine type, which is described for example in British patent application GB 1,541,427, is of minor importance.
All the industrial processes mentioned above have the disadvantage that the reaction of the nitrogen component with the alkylating agent is not complete so that the reaction products contain between 0.1 and 3% by weight unreacted starting materials. Since the content of free amines and unused alkylating agent has to be reduced to a low level in order to obtain toxicologically safe products of acceptable odor, there has been no shortage of attempts in the past to achieve this objective through the choice of suitable reaction conditions or by working up the reaction products.
Whereas the content of free amines in the solution of amphoteric or zwitterionic surfactants can be substantially reduced, for example, by using the alkylating agent in excess, carrying out the reaction at pH=8 to 10 [DE 29 26 479 A1], eliminating most of the amine by distillation or destroying the amine by oxidation [DE 20 63 422 A1], heating the surfactant solutions under alkaline conditions, even for several hours, only leads to a slight reduction in the residual content of alkylating agent.
Accordingly, the problem addressed by the present invention was to provide a process by which the residual content of alkylating agent in solutions of amphoteric or zwittionionic surfactants could be reduced to less than 0.01% by weight, based on a solids content of 100% by weight of the surfactant solutions.

Process for reducing the residual content of free alkylating agent in aqeous solutions of amphoteric or zwitterionic surfactants


Auto-tracking bit line reference schemes have common reference and normal word lines and generate a “½ cell current” reference by providing reference bit lines with pull-up devices having a different effective size from the pull-up devices for bit line or by programming reference cells to different levels. To provide a true “current mirror” connection of the pull-up devices of bit line and one or more reference bit lines, an additional bias bit line causes currents through the pull-up devices for the selected bit line and the reference bit lines to mirror current through the pull-up device for the bias bit line. Embodiments of the invention can be used with binary and multiple-bit-per cell memory and with a variety of sense amplifiers, memory array architectures, and memory cell structures.

Sensing operations, which read or otherwise determine the states of memory cells in semiconductor memory devices, often use a reference signal and generate a data value depending on the relation of a bit line signal to the reference signal. The bit line signal generally depends on a current through or from a memory cell connected to the bit line and is subject to variations in the performance of the memory cell. Such performance variations may arise from variations in the fabrication process for the memory, the temperature or other operating conditions, the endurance or cycling history, the age of the memory cell, or the lapsed time since data was written to the memory cell. The reference signal preferably tracks these performance variations of the memory cell so that sensing operations provide consistent results, i.e., output the same data value, despite the variations.
FIG. 1 illustrates a conventional bit line reference scheme for a conventional Flash memory array 100 using a single-ended sense amplifier 150. Flash memory array 100 has a separate bank 110 of reference cells 115 that are substantially identical to and operate in the same manner as memory cells 125 in a bank 120. Reference memory cells 115, in this example, are set at an "erased" or "low" threshold voltage (Vt) state.
FIG. 1 shows memory cells 125 and reference memory cells 115 sharing the same word lines WL1 to WLn and word line drivers 140. In general, using the same word lines for memory and reference cells provides better tracking of gate or word line voltages and eliminates the need for separate reference word line decoders and drivers and associated redundancy circuits. In a standby mode of memory array 100, all word lines WL1 to WLn are grounded to turn off all memory cells 125 so that little or no bit line current flows, and single-ended sense amplifier 150 (and its output signal SAout) are set to a state that corresponds to reading a "programmed" or "high Vt" memory cell.
For a sensing operation, a selected word line driver 140 activates a selected word line. As a result, an activated reference cell 115 provides a reference current on a reference bit line BLref. The reference current is preferably about equal to the normal cell current through a virgin or low Vt memory cell in memory array 120. Selected memory cells 125 that are connected to the activated word line conduct or not depending upon the threshold voltage states of the memory cells.
P-channel pull-up devices 131 and 132 connected in a "current-mirror" configuration mirror the reference current from reference bit line BLref to bit lines BLm. As a result, the ratio of the sizes of P-channel pull-up devices 131 and 132 determines the percentage of the normal cell current that a selected memory cell 125 must conduct to trip the corresponding sense amplifier 150. Typically, this ratio ranges from about 2:1 to 4:1, (e.g., W1/L1 is between 2W2/L2 and 4W2/L2, where transistor 131 has channel width W1 and channel length L1 and transistor 132 has channel width W2 and channel length L2. If the ratio is 4:1, and if the normal cell current through a virgin or low Vt reference cell is 40 μA, the selected memory cell must conduct more than 10 μA to trip single-ended sense amplifier 150, causing output signal SAout to represent the data value "1." Accordingly, a virgin or low Vt memory cell, which conducts a current greater than 10 μA will trip single-ended sense amplifier 150, but a programmed memory cell, which conducts a current less than 10 μA, does not trip sense amplifier 150, causing output signal SAout to represent the data value "0."
FIG. 2 shows a contactless buried diffusion memory array 200 implementing a sensing operation that uses a reference signal and single-ended sense amplifier 150 in the same manner as described above for memory array 100 of FIG. 1. Memory array 200 has a bank 210 of reference cells 215, a bank 220 of memory cells 225, and bit line pull-up devices 131 and 132. In particular, the activated reference cell 215 conducts a reference current on reference bit line BLref that is about equal to the normal current through a virgin or low Vt memory cell, and bit line pull-up devices 131 and 132 mirror the reference current to bit lines BLm. Single-ended sense amplifiers 150, which are connected to the bit lines BLm, will trip or not depending on whether or not selected memory cells 225 conduct a current greater than the mirrored current.
FIG. 3 illustrates a conventional Flash memory array 300 implementing a conventional bit line reference scheme for a sense amplifier 350 having differential inputs. In memory array 300, reference cells 115 in separate reference bank provides a reference-current approximately equal to a "½ cell reference current", which is about half-way between the current through a memory cell in the erased or low Vt state and a "zero cell current" through a memory cell 125 in the programmed or high Vt state. Memory array 300 uses two P-channel bit line pull-up devices 331 and 332 that differ from devices 131 and 132 of FIG. 1 in that devices 331 and 332 have approximately the same sizes and are not connected to form a current-mirror. Additionally, a common Vbias voltage, which can be a reference voltage having a voltage level lower than Vcc minus the threshold voltage Vtp of a pull-up device, controls P-channel bit line pull-up devices 331 and 332. Accordingly, in memory array 300, bit line pull-up devices 331 and 332 conduct the same or nearly the same amount of current.
A voltage difference that develops between bit line BLm and reference bit line BLref is positive or negative depending on whether the selected memory cell 125 conducts less or more current than the selected reference cell 115 conducts. Differential sense amplifier 350 can sense a small voltage difference that develops between the I/O and I/O reference lines that are connected to the selected bit line BLm and the reference bit line BLref. Sense amplifiers 350 with differential inputs generally provide faster sensing than do single-ended sense amplifiers 150 (FIGS. 1 and 2). In addition, sense amplifiers 350 with differential inputs generally provide better tracking performance and noise cancellation due to the inherent "differential" input and output paths.
A difficulty in memory array 300 relates to the generation of the "½ cell reference current" that is about half the normal current through a virgin memory cell. FIG. 3 shows a common approach having reference word lines RWL1 to RWLn that are physically separated from the normal word lines WL1 to WLn. For a sensing operation, drive circuits 340 associated with reference word lines RWL1 to RWLn activate a selected reference word line using a voltage VR2 that is lower than the normal word line voltage VR1, (e.g., VR2 is about ½ VR1), in order to generate the "½ cell current". During programming, reference word lines RWL1 to RWLn typically remain "low" because the reference memory cells 115 typically remain in the erased or low Vt state.
FIG. 4 illustrates a contactless memory 400 that implements the reference techniques of FIG. 3 in a contactless memory architecture. Memory array 400 like memory array 300 employs word lines WL1 to WLn that are separate from reference word lines RWL1 to RWLn, and the difference in the bias voltages VR1 and VR2 respectively on the selected word lines and the selected reference word line causes the selected reference cell 215 to conduct only the desired "½ cell reference current."
The reference scheme of FIGS. 3 and 4 requires a substantial amount of supporting circuits, silicon area, power consumption, and increased circuit complexity. Typical required additional supporting circuits (not shown) include: a "precision" reference word line voltage generator; reference word line decoders and driver circuits, which are typically located at an end of the array opposite to the normal word line decoders and drivers; and reference word line redundancy circuits for the reference word line decoders and drivers. For this reference scheme, selection of the reference word line (and bank selects in memory array 500) preferably matches the location of the selected normal word line, in order to track the source line resistance and/or buried diffusion bit line and source line resistances, as well as the memory cell orientation effect. However, reference word lines RWL1 to RWLn physically differ from normal word lines WL1 to WLn, and the reference cells 115 or 215 cannot achieve 100% tracking with memory cells 125 or 225. For example, making the voltage levels for reference cells 115 or 215 perfectly track the corresponding voltage levels for memory cells 125 or 225 for temperature, supply voltage Vcc, and process variations would be very difficult or impossible. Also, the reference cells 115 and 215 experience disturb effects that differ from disturb effects on normal memory cell 125 or 225, and references cells 115 or 215 do not track the endurance cycling and aging effects on memory cells 125 or 225.
In view of the limitations of current referencing techniques for sensing operations, circuits and processes that provide good tracking of memory cell performance and fast sensing without undue power consumption or circuit complexity are sought.

Bit line reference circuits for binary and multiple-bit-per-cell memories


A hydraulic emergency control for changing the hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission (10) for varying the clamping force ratio has a pump (20) in an open hydraulic circuit that supplies the respective piston chambers (17, 13) of the secondary and primary axial adjustment mechanisms with hydraulic oil. The primary and secondary oil pressures are regulated by separate oil pressure limiting valves (30, 40). At least one throttle valve (51) is arranged between the pump (20) and the output pipe (92) of the open hydraulic circuit, at a point where the pump volumetric flow can be influenced. The hydraulic emergency control allows a starting transmission ratio to be set in a low range when starting the vehicle, whereas a very small reduction ratio is selected at a high driving speed and at light throttle.

The invention relates to a hydraulic emergency control.
A hydraulic emergency control for an electronically controlled, continuously variable transmission (continuously variable transmission, CVT) is described in DE-42 34 103 A1. The CVT transmission which is preferably employed in motor vehicles, has a control for emergency driving operations which, when the electrical control of normal driving operations fails, causes a switching position with a high gear ratio in order to provide more advantageous restart and start-up conditions. Among other things, the ratio of primary to secondary clamping force between the pulling means and the pairs of beveled disks is maintained constant by means of this control through an intermediate gear range. In the intermediate gear range the gear ratio changes as a function of the torque requirements of the power take-off shaft. With a high demand a high gear ratio is selected, while a low gear ratio is set with a low demand. The means required for this are recited in the description of FIGS. 1 and 2.

Hydraulic emergency control for changing hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission for varying the clamping force ratio


A fiber reinforced core panel is formed from strips of plastics foam helically wound with layers of rovings to form webs which may extend in a wave pattern or may intersect transverse webs. Hollow tubes may replace foam strips. Axial rovings cooperate with overlying helically wound rovings to form a beam or a column. Wound roving patterns may vary along strips for structural efficiency. Wound strips may alternate with spaced strips and spacers between the strips enhance web buckling strength. Continuously wound rovings between spaced strips permit folding to form panels with reinforced edges. Continuously wound strips are helically wrapped to form annular structures, and composite panels may combine both thermoset and thermoplastic resins.

Structural sandwich panels having cores comprised of low density closed cell material, such as closed cell plastics foam material, and opposing skins comprised of fibrous reinforcing mats or fabrics in a matrix of cured resin, have been used for many decades in the construction of a wide variety of products, for example, boat hulls and refrigerated trailers. The foam core serves to separate and stabilize the structural skins, resist shear and compressive loads, and provide thermal insulation.
The structural performance of sandwich panels having foam cores may be markedly enhanced by providing a structure of fibrous reinforcing members within the foam core to both strengthen the core and improve attachment of the core to the panel skins, for example, as disclosed in applicant's U.S. Pat. No. 5,834,082. When porous and fibrous reinforcements are introduced into the closed cell foam core and a porous and fibrous skin reinforcing fabric or mat is applied to each face of the core, adhesive resin, such as polyester, vinyl ester or epoxy, may be flowed throughout all of the porous skin and core reinforcements by differential pressure, for example under a vacuum bag. While impregnating the fibrous reinforcements, resin does not saturate the plastic foam core because of its closed cell composition. The resin then co-cures throughout the reinforced structure to provide a strong monolithic panel.
It is desirable to produce sandwich panels of enhanced structural performance by improving the structural connections and support among reinforcing members within the foam core and between the core and the panel skins. This is desirable in order to resist buckling loads in the reinforcing members, to prevent premature detachment of reinforcing members from one another and from the skins under load, and to provide multiple load paths for the distribution of forces applied to the panel. Existing fiber reinforced core products offer important improvements over unreinforced foam in this regard but fail to integrate fully the separate reinforcing elements of the core into a unified and internally supported structure. For example, in a grid-like configuration of fibrous reinforcing sheet-type webs in which a first set of continuous webs is intersected by a second set of interrupted or discontinuous webs, the webs do support each other against buckling. However, under severe loading conditions, the discontinuous webs tend to fail at the adhesive resin bond to the continuous webs along their narrow line of intersection. This tendency may be substantially reduced by providing resin filled fillet grooves in the foam along the lines of intersection as disclosed in the above mentioned patent. Moreover, since the reinforcing fibers of interrupted webs terminate at each intersection with a continuous web, the structural contribution of those fibers is substantially less than that of the fibers of the continuous webs.
In the case of strut or rod type core reinforcements comprising rovings of fiberglass or carbon fiber or other fibers which extend between the faces of the core, individual struts within a given row of struts may intersect each other in a lattice configuration. This supplies buckling support to each strut, but only in the plane of the strut row. To achieve bi-directional support, struts of a first row must extend through the filaments of struts of an intersecting row. This requires difficult and costly levels of accuracy and control in machine processing, since all struts must be precisely positioned in three dimensions.

This patent is subject to a terminal disclaimer.

Fiber reinforced composite cores and panels


A lower shield has an area smaller than an upper shield. A lead is constituted of a thin lead portion and a thick lead portion, the thin lead portion being formed in a reproduction gap between the upper and lower magnetic shield layers and the thick lead portion being formed spaced apart from the end of the lower magnetic shield layer in the depth direction and extending downward in the thickness direction at a level lower than the thin lead portion. The upper surface of the lead is not formed with a step. The thin and thick lead portions are connected via a contact hole formed through a lower reproduction gap layer.

a) Field of the Invention
The present invention relates to a magnetic head of a hard disk drive or the like and its manufacture method. More particularly, the invention relates to a magnetoresistive type thin film magnetic head of a magnetic shield type and its manufacture method capable of lowering the resistance of a lead to suppress heat generation and prevent insufficient insulation of an upper magnetic shield layer to thereby improve manufacture yield. A magnetoresistive type thin film magnetic head is hereinafter called an "MR type magnetic head" and includes a giant magnetoresistive (GMR) type thin film magnetic head.
b) Description of the Related Art
An MR type magnetic head is used for only reproduction of information recorded in a magnetic recording medium by detecting a magnetic field generated from magnetic poles of a magnetic recording medium. As compared to reproduction by an induction type magnetic head, the track density and a line record density can be made higher. An induction type magnetic head for recording is combined with an MR type magnetic head to form an induction type and magnetoresistive type composite magnetic head (hereinafter called an "induction type and MR type composite magnetic head").
FIG. 2 shows the structure of an MR type magnetic head (with an upper reproduction gap layer and an upper magnetic shield layer being removed) of a conventional induction type and MR type composite magnetic head used for hard disks. An MR magnetic head 10 is formed on a slider substrate 12 made of Al.sub.2 O.sub.3 --TiC or the like by sequentially laminating a protective layer 14 made of non-magnetic insulating material such as Al.sub.2 O.sub.3, a lower magnetic shield layer 16 made of soft magnetic material such as NiFe alloy, and a lower reproduction gap layer 18 made of non-magnetic insulating material such as Al.sub.2 O.sub.3. On the reproduction gap layer 18, right and left leads (electrodes) 20, 20 are formed. An MR element 11 is connected between the leads 20, 20. The tip surface of the MR element 22 forms a recording medium facing surface (ABS: air bearing surface). The MR element 22 is made of a lamination of an MR film, a spacer, a transverse bias film, and the like. Each lead 20 is made of a lamination of a magnetic material layer (magnet layer) 26 for enhancing uniaxial anisotropy of the MR film to suppress Barkhausen noises (longitudinal bias layer) and an electrically conductive film 28 for lowering the electrical resistance of the lead 20.
In the structure shown in FIG. 2, the tip surface or ABS of the lead requires some mechanical strength and corrosion resistance because it is subject to a lapping process. Generally, the magnet film 26 is made of Co-containing alloy, and the electrically conductive film 28 is made of Ta or the like. These lead materials have a relatively high resistivity so that when a sense current flows through the MR element 22, heat generation becomes large and electromigration may be accelerated which is one cause of lowering the reliability of the magnetic head and considerably shortening the lifetime thereof. Electromigration is a phenomenon in which when a sense current flows at a high temperature, metal atoms are liberated and moved to increase the resistance of the leads.
In order to lower the resistance of leads, another structure has been proposed as shown in FIG. 3. In this structure, contact leads 30, 30 made of the same materials as the leads shown in FIG. 2 are formed only at regions near the ABS 24. Relatively thick main bulk electrodes 32, 32 made of material having a relatively low resistivity are formed in contact with and at the back of the contact leads along the depth direction of the MR element. Leads 34, 34 are constituted of these contact leads 30, 30 and main leads 32, 32.
An MR type magnetic head of a magnetic shield type (a magnetic shield type MR head) has an upper reproduction gap layer covering the MR element and leads, this gap layer being made of non-magnetic material such as A1.sub.2 O.sub.3. On this upper reproduction gap layer, an upper magnetic shield layer is formed being made of conductive and magnetic shield material. The upper magnetic shield layer is made of soft magnetic material such as NiFe alloy same as the lower magnetic shield layer. With the structure shown in FIG. 3, a large step 36 is formed on the lead 34 so that the upper reproduction gap layer cannot be formed to have a predetermined thickness at this step 36. It is therefore difficult to provide perfect electrical insulation between the lead 34 and the upper magnetic shield layer, and manufacture yield is caused to be lowered.

Magnetoresistive thin film magnetic head with specific shapes of leads


Compositions and methods are provided for the alleviation of pathology induced by traumatic brain injury.

Traumatic brain injury (TBI) afflicts up to two million people annually in the United States, and is the primary cause of death and disability in young adults and children. TBI results in long-lasting cognitive impairment and currently there are no effective therapies to mitigate or rectify this pathology. TBI often causes enduring disabilities including emotional alterations, cognitive impairment and memory dysfunction. These functional deficits result from changes in hippocampal network excitability that are precipitated by regional imbalances between excitatory and inhibitory synaptic activity, including decreased network excitability in area CA1 and increased excitability in the dentate gyms. Furthermore, both neuronal and astrocytic metabolism following injury are altered, including increased accumulation of lactate and an increase in intracellular glutamate, but the interaction between astrocyte-derived metabolites and neuronal metabolism following injury is not fully understood. New methods of treatment for the inhibition and/or prevention of the pathology associated with traumatic brain injury are needed.

Compositions and methods for the treatment of brain injury


A method for refueling hydrogen fuel cell powered vehicles is disclosed, that is capable of automatically disabling the vehicle systems, resetting the vehicle systems to allow for normal vehicle operation after the refueling event is complete, and determining if a faulty refueling event has been detected and allows normal vehicle operation.

Vehicle fueling stations typically require that vehicles be turned off during refueling to minimize the risks of vehicle damage associated with vehicle operation during the refueling process. Ensuring vehicles are not operated during refueling is primarily accomplished through enforcement by fueling station attendants, or is a voluntary process depending upon the cooperation of the vehicle operator.
As hydrogen fuel cell power plants are increasingly being integrated into vehicles, preventing operators from driving away during refueling is becoming increasingly important in order to prevent damage to both the vehicle and fuel station equipment.
It would be desirable to have a hydrogen refueling system that automatically disables vehicle systems in order to militate against damage to the vehicle when refueling is occurring. It would be further desirable to have a hydrogen vehicle refueling system that resets the vehicle systems after the refueling event is complete. Also, it would further be desirable to have a hydrogen refueling system that determines if a faulty refueling event has been detected and maintains typical vehicle operation.

Hydrogen powered vehicle refueling strategy


The present invention relates to improved methods and assays for the detection of AAV neutralizing antibodies in sera. The present invention provides safe, sensitive and high throughput neutralization assays for antibody detection.

Gene transfer vectors based on adeno-associated virus (AAV), i.e., AAV vectors/particles, have become favored vectors because of characteristics such as an ability to transduce different types of dividing and non-dividing cells of different tissues and the ability to establish stable, long-term transgene expression. Though adeno-associated virus (AAV) has not been associated with any human diseases, its presence can be detected in many human tissues. The infected individuals develop immune response to AAVs. In the past, a full spectrum of immune responses to AAV capsids and/or AAV serotypes has been assessed to include innate responses, neutralizing antibodies and cytotoxic T cell responses, in human populations. Roughly 70% of the human population has neutralizing antibody (NAb) titers to AAV2 serotype (Erles et al., J. Med Virol., 1999, 59(3): 406-411; and Calcedo et al., J. of Infectious Diseases, 2009; 199: 381-390). Additional studies have also estimated the prevalence of NAbs to other AAV capsids, including AAV1, AAV6, AAV7, AAV8 and AAV9 (Calcedo et al., J. of Infectious Diseases, 2009, 199: 381-390; and Boutin et al., Hum Gene Ther., 2010, 21(6): 704-712). In addition, evidence that NAbs to AAV2 can reduce transduction efficiency against other AAV capsids and/or AAV serotypes raises the concern for cross-reactivity of capsid specific or serotypic NAbs. In vitro NAb assays and cross administration of AAV vectors in animals demonstrated that several NAbs have strong cross reactivity to different AAV serotypes (Calcedo et al., J. of Infectious Diseases, 2009, 199: 381-390; and Harbison et al., J. Gen Virol., 2012, 93(2): 347-355).
The pre-existing neutralizing antibody titers to AAV capsids and/or AAV serotypes and their cross-reactivity, or those induced by administration, have emerged as a concern and challenge for clinical applications of gene therapy and genetic vaccine mediated by AAV vectors. The pre-existing NAbs recognizing viral capsids could inhibit AAV entry and transgene delivery to the host cells, thereby preventing long-term therapy in humans. Determining the presence and cross-reactivity of neutralizing antibodies in a subject is critical for clinical applications of AAV vectors and the design of the serotypic capsids of AAV vectors for gene therapy and genetic vaccine.
Neutralizing antibodies and their cross-reactivity to different AAV capsids and/or AAV serotypes are typically evaluated in various types of viral neutralization assays or tests, which are modified immune assays based on antibody-antigen interaction. In general, these assays involve production of recombinant AAV vectors with the helper adenovirus (Adv). Adenovirus (Adv) is a human pathogenic virus which causes respiratory illnesses and other diseases. There are stringent safety requirements to perform viral neutralization assays in the laboratory, and potential risk of infection to the operators during the assays and tests. Therefore, these assays can hardly be considered appropriate as routine high-throughput tests, particularly in a clinical setting.
Thus, there is a continuing need for routine, safe and reliable methods for viral neutralization assays. The present invention provides a new neutralization assay for determining neutralizing antibodies to specific AAV capsids and/or AAV serotypes and their cross reactivity to different AAV capsids and/or serotypes, without the helper Adv.

Assays for the detection of AAV neutralizing antibodies