Disclosed are an apparatus and a method for generating a preamble sequence in an orthogonal frequency division multiplexing communication system including a reference base station and a plurality of non-reference base stations and employing m sub-carriers in a frequency domain. A reference preamble sequence having a length equal to n is generated and mapped on a one-to-one basis with n sub-carriers of the m sub-carriers. A final preamble sequence equivalent to the reference preamble sequence is generated when the base station is a reference base station, or a phase of the reference preamble sequence is shifted by a predetermined phase in order to generate a phase-shifted final preamble sequence when the base station is a non-reference base station, thereby minimizing interference between neighbor base stations.

1. Field of the Invention
The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing) communication system, and more particularly to an apparatus and a method for generating a preamble sequence for minimizing the interference between neighbor cells in an OFDM communication system.
2. Description of the Related Art
Generally, a wireless communication system includes a Node B and user equipment (UE) in order to provide users with wireless communication services. The Node B and the UE support the wireless communication services by using transmission frames. Accordingly, the Node B and the UE must obtain mutual synchronization for transmitting and receiving the transmission frames. To this end, the Node B transmits a synchronizing signal to the UE to allow the UE to recognize a start point of the frame transmission. Upon receiving the synchronizing signal from the Node B, the UE checks the frame timing of the Node B and demodulates the transmission frames received therein according to the frame timing. In general, a preamble sequence, which is preset between the Node B and the UE, is used as a synchronizing signal.
In addition, a preamble sequence used in an OFDM communication system must have a low peak to average power ratio (PAPR). A long preamble sequence is transmitted to the UE from the Node B. The long preamble sequence includes a preamble sequence required for coarse synchronization and a short preamble sequence required for micro frequency synchronization. In addition, the short preamble sequence is transmitted to the Node B from the UE so as to obtain the micro frequency synchronization. The following examples described why the preamble sequence of the OFDM communication system must have a low PAPR. First, the OFDM communication system is a multi carrier communication system employing a plurality of carriers, that is, a plurality of sub-carriers, so orthogonality of the sub-carriers becomes an important factor. Thus, each sub-carrier has its own phase such that the sub-carriers are orthogonal to each other. If the phase is changed during the sub-carrier transmission/reception procedure, the sub-carriers may overlap with each other. In this case, the overlapped sub-carriers may deviate from a linear interval of an amplifier provided in the OFDM communication system, so a normal signal transceiving operation is impossible. For this reason, the OFDM communication system uses the preamble sequence having a minimized PAPR.
The OFDM communication system transmits data to various UEs by time-multiplexing one frame. In addition, the OFDM communication system transmits a frame preamble sequence for a predetermined interval from a start point of the frame in order to indicate the beginning of the frame transmission. Since data to be transmitted to each UE may be irregularly included in one frame, a burst preamble sequence indicating a start of the data may be transmitted prior to the transmission of each data. Accordingly, the UE must receive a data preamble sequence in order to recognize the start point of the data transmission. That is, the UE must synchronize with the start point of data transmission in order to receive the data, so the UE needs to be synchronized with the preamble sequence commonly used in the OFDM communication system before receiving a signal.
In the meantime, a source coding scheme, a channel coding scheme and a modulation scheme of the OFDM communication system are identical to those of communication systems which do not employ the OFDM scheme. A Code Division Multiple Access (CDMA) communication system transmits data by spreading the data. However, the OFDM communication system transmits data after performing Inverse Fast Fourier Transform (IFFT) with regard to the data and inserting a guard interval signal into the data. Thus, different from the CDMA communication system, the OFDM communication system can transmit broadband signals with a relatively simple hardware structure. The OFDM communication system combines a plurality of bit/symbol arrays after modulating data and inputs parallel bit/symbol arrays into an IFFT unit corresponding to a frequency domain, thereby outputting IFFT time domain signals. The IFFT time domain signal is obtained by multiplexing a broadband signal into a plurality of narrow band sub-carrier signals. In addition, a plurality of modulation symbols are transmitted through the IFFT procedure during one OFDM symbol interval.
If the above IFFT OFDM symbols are transmitted in the OFDM communication system, interference may occur between previously-transmitted OFDM symbols and currently-transmitted OFDM symbols. In order to avoid the interference between the OFDM symbols, the guard interval signal is inserted into the data. The guard interval signal can be created through a "cyclic prefix" scheme, in which predetermined number end samples of the OFDM symbols in the time domain are copied and inserted into effective OFDM symbols, or a "cyclic postfix" scheme, in which predetermined number of beginning samples of the OFDM symbols in the time domain are copied and inserted into effective OFDM symbols. Sizes of the beginning and end samples used in the cyclic prefix scheme and the cyclic postfix scheme are predetermined in the OFDM communication system. A receiver can time-frequency synchronize the OFDM symbols by using the characteristics of the guard interval signals, which are created by inserting the copied beginning or end parts of the OFDM symbols into the effective OFDM symbols.
A transmission signal from a transmitter becomes distorted while passing through a wireless channel environment, and the receiver may receive the distorted transmission signal. Upon receiving the distorted transmission signal from the transmitter, the receiver obtains time-frequency synchronization by using a preamble sequence, which is preset between the transmitter and the receiver, and performs channel estimation. After that, the signals are demodulated into frequency domain symbols through fast Fourier transform (FFT). Then, the receiver performs a channel decoding process and a source decoding process, which correspond to the channel coding in the transmitter, with regard to the demodulated symbols, thereby decoding the symbols into information data.
The OFDM communication system employs the preamble sequence when performing the frame timing synchronization, frequency synchronization and channel estimation. It is also possible for the OFDM communication system to perform the frame timing synchronization, frequency synchronization and channel estimation by using the guard interval and pilot sub-carriers instead of the preamble sequence. When the preamble sequence is employed, known symbols are transmitted with every frame or at a start point of a data burst. At this time, estimated time-frequency-channel information is used for updating transmission data by using information related to guard interval signals and sub-carriers.
Hereinafter, a preamble sequence structure employed in a conventional OFDM communication system will be described with reference to FIGS. 1 and 2.
FIG. 1 is a diagram showing a structure of a long preamble sequence used in the conventional OFDM communication system. The current OFDM communication system uses the same preamble sequence in a down link (DL) and an up link (UL). Referring to FIG. 1, the long preamble sequence includes four 64-length sequences and two 128-length sequences. According to the characteristic of the OFDM communication system, the cyclic prefix is added in front of the four 64-length sequences and in front of the two 128-length sequences. In addition, the signals before the IFFT are frequency domain signals and the signals after the IFFT are time domain signals. The long preamble sequence shown in FIG. 1 is a time domain long preamble sequence obtained after the IFFT has been carried out.
In addition, the long preamble sequence in a frequency domain before the IFFT is represented as follows:
                    S                          (                                    -              100                        :            100                    )                    =                                                  {                                                    +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                                                                                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                                                                                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                                                                                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                                              0            ,            0            ,            0            ,            0            ,                                          -                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                                                                                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                                                                                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              +                        ,            0            ,            0            ,            0            ,                                          -                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                                                                                1                            +              j                        ,            0            ,            0            ,            0            ,                                          -                1                            -              j                        ,            0            ,            0            ,            0            ,                                          +                1                            -              j                        ,            0            ,            0            ,            0            ,                                          -                1                            +              j                        ,            0            ,            0            ,            0            ,                                          +                                                                                1                            +              j                                }                *                  sqrt                                (            2            )                          *                  sqrt                                (            2            )                                                                    P                          (                                    -              100                        :            100                    )                    =                        {                                    -              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,                          0              -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,                          0              +              1                        ,            0            ,                          -                                                                                1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,                          0              -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -                                                                                1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,                          0              -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,                          0              -              1                        ,            0            ,                          -                                                                                1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                          -                                                                                1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                                                                                0            ,                          0              -                                                                        1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          +                                                                        1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,                          0              -              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          -                                                                        1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -                                                                        1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          +              1                        ,                          0              +              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          -                                                                        1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,                          0              -              1                        ,            0            ,                          -              1                        ,            0            ,                          +              1                        ,            0            ,                          -              1                                }                *                  sqrt                                (            2            )                          *                  sqrt                                (            2            )
In the above long preamble sequence of the frequency domain, the numbers shown in S(−100:100) and P(−100:100) represent positions of sub-carriers employed when performing the IFFT, which will be described later with reference to FIG. 3. S(−100:100) represents a frequency domain sequence including four 64-length sequences and P(−100:100) represents a frequency domain sequence including two 128-length sequences. In S(−100:100) and P(−100:100), sqrt(2) signifies root 2, and sqrt(2)*sqrt(2) signifies two-step amplification for increasing the transmit power of S(−100:100) and P(−100:100).
A structure of a short preamble sequence will be described with reference to FIG. 2.
FIG. 2 is a diagram showing a structure of a short preamble sequence of a conventional OFDM communication system. Referring to FIG. 2, the short preamble sequence includes two 128-length sequences. The cyclic prefix is added in front of the two 128-length sequences. In addition, the short preamble sequence shown in FIG. 2 is a time domain short preamble sequence after the IFFT. P(−100:100) is a frequency domain short preamble sequence.
The long preamble sequence must be created by taking the following factors into consideration.
(1) Low PAPR
In order to maximize the transmission rate of a power amplifier provided at a transmission terminal of a transmitter of an OFDM communication system, the OFDM symbol must have a low PAPR. As mentioned above, after the IFFT has been performed with regard to the signal, the signal is input into a power transmitter. At this time, since the power transmitter has a non-linear characteristic, the low PAPR is required. That is, it is necessary for the time domain OFDM symbol corresponding to an IFFT output terminal to have a low PAPR, and the OFDM symbols must have uniform distribution so as to minimize the PAPR. In other words, if symbols having a low cross correlation are provided in an IFFT input terminal of a transmitter, that is, in the frequency domain, the PAPR can be reduced.
(2) Parameter estimation required for communication initialization
Parameter estimation includes channel estimation, frequency offset estimation, and time offset estimation.
(3) Low complexity and overhead
(4) Coarse frequency offset estimation
The long preamble sequence created by taking the above factors into consideration has the following functions.
(1) The long preamble sequence including the four 64-length sequences is used for time offset estimation and coarse frequency offset estimation.
(2) The long preamble sequence including the two 128-length sequences is used for micro frequency offset and channel estimation.
The long preamble sequence is used in the OFDM communication system for the purpose of following objects.
(1) A first preamble sequence of a forward PDU (protocol data unit)
(2) Initial ranging
(3) Bandwidth request ranging
In addition, the short preamble sequence is used in the OFDM communication system for the purpose of following objects.
(1) Backward data preamble sequence
(2) Periodic ranging
Since the OFDM communication system can obtain precise synchronization by performing initial ranging and periodic ranging, the backward data preamble sequence is mainly used for the purpose of channel estimation. The PAPR, performance and complexity must be considered when performing the channel estimation. In a case of a short preamble sequence, the PAPR is 3.5805dB, and various channel estimation algorithms including minimum mean square error (MMSE) and least square (LS) can be used.
A mapping relationship between the sub-carriers and the preamble sequence when performing the IFFT in the conventional OFDM communication system will be described with reference to FIG. 3.
FIG. 3 is a diagram illustrating a mapping relationship between sub-carriers and the preamble sequence when performing the IFFT in the conventional OFDM communication system.
Referring to FIG. 3, the OFDM communication system employs 256 sub-carriers including #−128 to #127 sub-carriers, and 200 sub-carriers including #−100 to #100 sub-carriers are actually used. In FIG. 3, numbers shown at a front of an IFFT unit represent frequency components, that is, the numbers of the sub-carriers. Herein, from among the 256 sub-carriers, 200 sub-carriers except for a #0 sub-carrier, #−128 to #−101 sub-carriers, and #101 to #127 sub-carriers are actually used. When the #0 sub-carrier, #−128 to #−101 sub-carriers, and #101 to #127 sub-carriers are transmitted, null data (that is, zero data) is inserted into the sub-carriers due to following reasons. First, the null data are inserted into the 0th sub-carrier because the #0 sub-carrier represents the DC component at a reference point of the preamble sequence, that is, in a time domain after the IFFT has been carried out. In addition, the null data is inserted into the 28 sub-carriers including #−128 to #−101 sub-carriers and 27 sub-carriers including #101 to #127 sub-carriers in order to insert a guard interval in a frequency domain because the above sub-carriers correspond to a high frequency band in the frequency domain.
Thus, if a frequency domain preamble sequence S(−100:100) or P(−100:100) is input into the IFFT unit, the IFFT unit maps the frequency domain preamble sequence S(−100:100) or P(−100:100) into corresponding sub-carriers and performs IFFT, thereby outputting a time domain preamble sequence.
A structure of a transmitter provided in a conventional OFDM communication system will be described with reference to FIG. 4.
FIG. 4 is a block diagram illustrating a structure of a transmitter provided in a conventional OFDM communication system. Referring to FIG. 4, if information bits to be transmitted are generated, the information bits are input into a symbol mapper 411. Upon receiving the information bits, the symbol mapper 411 modulates the information bits into symbols through a predetermined modulation scheme and sends the symbols to a serial to parallel converter 413. The predetermined modulation scheme includes a quadrature phase shift keying (QPSK) scheme and a 16 quadrature amplitude modulation (16QAM) scheme. Upon receiving the symbols from the symbol mapper 411, the serial to parallel converter 413 converts the symbols such that the symbols match with an A-point, which is an input number of an inverse fast Fourier transformer (hereinafter, referred to as IFFT unit) 419 and sends the symbols to a selector 417. In addition, a preamble sequence generator 415 generates preamble sequences under the control of a controller (not shown) and sends the preamble sequences to the selector 417. The selector 417 selects a signal output from the serial-to-parallel converter 413 or a signal output from the preamble sequence generator 415 according to a predetermined scheduling scheme and sends the signal to the IFFT unit 419.
Upon receiving the signal from the selector 417, the IFFT unit 419 performs A-point IFFT with regard to the signal and sends the signal to a parallel-to-serial converter 421. In addition, the parallel-to-serial converter 421 receives a cyclic prefix signal having a predetermined length in addition to the signal output from the IFFT unit 419.
The "cyclic prefix" signal is a guard interval signal. The guard interval signal can be inserted into the data through a "cyclic prefix scheme", in which predetermined number of end samples of the OFDM symbols in the time domain are copied and inserted into effective OFDM symbols, or a "cyclic postfix" scheme, in which predetermined number of beginning samples of the OFDM symbols in the time domain are copied and inserted into effective OFDM symbols. Sizes of the beginning and end samples used in the cyclic prefix scheme and the cyclic postfix scheme are predetermined in the OFDM communication system. In FIG. 4, the guard interval signals are inserted into the data through the cyclic prefix scheme. The parallel-to-serial converter 421 converts the signal output from the IFFT unit 419 and the guard interval signal into serial signals and sends the serial signals to a digital-to-analog converter 423. Upon receiving the serial signals from the parallel-to-serial converter 421, the digital to analog converter 423 converts the serial signals into analog signals and sends the analog signals to an RF (radio frequency) processor 425. The RF processor 425 includes a filter and a front end unit (not shown). The RF processor 425 processes the analog signals output from the digital-to-analog converter 423 such that the signals can be transmitted through air and sends the signals through an antenna.
A preamble sequence and a method for creating the preamble sequence in a conventional OFDM communication system employing N transmit antennas will be described.
In order to estimate the channels of the data transmitted through N transmit antennas in a receiver of the OFDM communication system employing N transmit antennas, it is necessary to transmit preamble sequences through N transmit antennas. However, if at least two antennas are provided in the OFDM communication system, a preamble sequence transmission scheme for estimating the channels of the data transmitted through the transmit antennas has not been yet suggested.
If the preamble sequence is allocated by assigning different sub-carriers to each transmit antenna, the receiver can perform channel estimation only for the sub-carriers assigned for the preamble sequence and cannot perform channel estimation for remaining sub-carriers. Therefore, if at least two transmit antennas are provided, a preamble sequence transmission rule is required for channel estimation with regard to all of the sub-carriers transmitted through the transmit antennas.
In addition, as mentioned above, the OFDM communication system must use a preamble sequence having a low PAPR. Studies and research have been extensively carried out for providing a preamble sequence having a low PAPR in a current OFDM communication system employing one transmit antenna. Similar to the OFDM communication system employing one transmit antenna, the OFDM communication system employing a plurality of transmit antennas must use a preamble sequence having a low PAPR. However, a method for providing the preamble sequence having the low PAPR in the OFDM communication system employing a plurality of transmit antennas has not yet been suggested. Accordingly, it is necessary to provide a method for generating the preamble sequence having low PAPR in the OFDM communication system.
Hereinafter, a preamble sequence and a method for generating the preamble sequence in a cellular OFDM communication system will be described.
First, since the cellular OFDM communication system has a multi-cell structure, all of the Node Bs of the cellular OFDM communication system must transmit the preamble sequence with the same time interval in order to minimize the interference between the neighbor Node Bs. If the Node Bs transmit the preamble sequence with different time intervals, interference between Node Bs may increase, thereby degrading performance of the preamble sequence and deteriorating synchronization and channel estimation performance.
In short, if all of the Node Bs transmit the preamble sequence with the same time interval, interference between the Node Bs can be minimized. Therefore, it is necessary to provide a method for generating the preamble sequence capable of obtaining synchronization and maximizing channel estimation performance by minimizing interference between neighbor Node Bs.

Apparatus and method for generating a preamble sequence in an orthogonal frequency division multiplexing communication system


According to a method for producing semiconductor chips, first grooves are formed in a semiconductor wafer at a front surface, dividing the semiconductor water into a plurality of regions, each region including a single device or an integrated circuit; a first metallization layer is formed in the first grooves; the semiconductor wafer is thinned to a desired thickness from the rear surface of the wafer; second grooves are formed in the semiconductor wafer at the rear surface at positions opposite the first grooves, exposing the first metallization layer; a second metallization layer is formed in the second grooves; a metal layer for heat radiation is formed on the rear surface of the wafer but not on the second metallization layer; and the first and second metallization layers in the first grooves are cut with a dicing blade to produce a plurality of semiconductor chips. Burrs of the metallization layers caused by the dicing are small and never protrude beyond the rear surface of the chip, resulting in a reliable junction between the chip and a mounting substrate in a subsequent die-bonding process.

FIG. 3(a) is a plan view illustrating a semiconductor wafer in which a plurality of ICs are formed in chequerboard pattern, and FIG. 3(b) is a cross section of a portion of FIG. 3(a). A surface protection film 11 is disposed on each chip region 10 containing an IC. Regions 12 where the surface protection films 11 are absent are dicing lines.
FIG. 4 illustrates a semiconductor wafer used in production of high output semiconductor devices. In FIG. 4, the wafer 1 is as thin as 20.about.30 microns and a plated heat sink (hereinafter referred to as PHS) 20 comprising Au or the like and having a thickness of 40.about.60 microns is disposed on the rear surface of the wafer 1 to improve heat radiation of the device. In production of usual devices, the PHS 20 is present except for regions opposite to the dicing lines 12. In case of high powered output devices, however, since the wafer is thin for the reason described above, the PHS 20 covers all the rear surface of the wafer 1 to prevent ICs contained in the wafer from being damaged by warping of the wafer which is caused by a difference in expansion coefficients between the wafer and the PHS.
A method for dividing the semiconductor wafer of FIG. 4 into chips by dicing is illustrated in FIGS. 5(a)-5(c).
Initially, as illustrated in FIG. 5(a), a dicing tape 40 is attached to the rear surface of the PHS 20. Then, as illustrated in FIG. 5(b), a dicing saw 30 cuts the wafer 1 along the dicing line 12. The dicing is carried out along all dicing lines 12 until the tip of the dicing saw 30 reaches into the dicing tape 40, whereby the wafer 1 is divided into chips as shown in FIG. 5(c). At this time, a burr 21 20.about.30 microns long is produced on the rear surface of the chip due to the ductility of the PHS 20.
After removing the dicing tape 40, each chip is bonded to a mount substrate 50 with solder 60 as shown in FIG. 6. Since the burr 21 protrudes from the rear surface of the chip, the solder 60 is not favorably adhered to the entire surface of the PHS 20, resulting in a faulty assembly.

Method for producing semiconductor chips


A distinct cultivar of Lantana plant named xe2x80x98Robpatpasxe2x80x99, characterized by its upright and outwardly spreading plant habit; mounded plant form; vigorous growth habit; rapid growth rate; freely flowering habit; and pale yellow to bright pink-colored flowers.

Lantana camara cultivar xe2x80x98Robpatpasxe2x80x99.
The present Invention relates to a new and distinct cultivar of Lantana plant, botanically known as Lantana camara, and hereinafter referred to by the cultivar name xe2x80x98Robpatpasxe2x80x99.
The new Lantana is a product of a planned breeding program conducted by the Inventor in Grain Valley, Mo. The objective of the breeding program is to create freely-flowering Lantanas with bright pink-colored flowers.
The new Lantana originated from a cross made by the Inventor during the spring, 1995, of the Lantana cultivar xe2x80x98Robpathotxe2x80x99, disclosed in U.S. Plant Pat. No. 12,266, as the female, or seed parent, with an unidentified Lantana selection as the male, or pollen parent. The new Lantana was selected during the winter, 1995, as a single plant from the resulting progeny by the Inventor in a controlled environment in Grain Valley, Mo., on the basis of its bright pink-colored flowers.
Asexual reproduction of the new cultivar by terminal cuttings taken in a controlled environment in Grain Valley, Mo., has shown that the unique features of this new Lantana are stable and reproduced true to type in successive generations.
Plants of the cultivar xe2x80x98Robpatpasxe2x80x99 have not been observed under all possible environmental conditionas. The phenotype may vary somewhat with variations in environment and culture such as temperature, light intensity, daylength, water status, and/or fertilizer rate or type without, however, any variance in genotype.
The following traits have been repeatedly observed and are determined to be the unique characteristics of xe2x80x98Robpatpasxe2x80x99. These characteristics in combination distinguish xe2x80x98Robpatpasxe2x80x99 as a new and distinct Lantana cultivar:
1. Upright and outwardly spreading plant habit; mounded plant form.
2. Vigorous growth habit; rapid growth rate.
3. Freely flowering habit.
4. Pale yellow to bright pink-colored flowers.
Plants of the new Lantana are comparable to plants of the female parent, the cultivar xe2x80x98Robpathotxe2x80x99. In side-by-side comparisons conducted in Grain Valley, Mo., plants of the new Lantana have bright pink-colored opened flowers whereas plants of the cultivar xe2x80x98Robpathotxe2x80x99 have magenta-colored opened flowers.
Plants of the new Lantana differ from plants of the male parent, the unidentified Lantana selection, and other Lantana cultivars known to the Inventor primarily in the new Lantana""s unique combination of mounded plant habit, bright pink opened flower color, and freely-flowering habit.


A light emitting element, including an anode, a cathode, a hole transport layer disposed between the anode and the cathode and in the side of the anode, and a light emitting layer disposed between the anode and the cathode and in the side of the cathode, wherein the hole transport layer includes, a first region disposed in the side of the anode and composed of a first organic polymer, and a second region disposed in the side of the light emitting layer and composed of a second organic polymer having a weight-average molecular weight different from the weight-average molecular weight of the first organic polymer.

1. Technical Field
The present invention relates to a light emitting element, a display device and an electronic instrument.
2. Related Art
An organic electroluminescence element (herein after referred to as an organic EL element) having a structure composed of at least one light emitting organic layer (an organic electroluminescence layer) sandwiched by a cathode and an anode can be driven by applying a significantly low voltage in comparison with a inorganic EL element, and can be manufactured as elements with various luminescent colors. Such an element is described in documents such as, for example, Appl. Phys. Lett. 51(12), 21 Sep. 1987, p. 913, Appl. Phys. 71(1), 7 Jul. 1997, p. 34, Nature 357,477 1992, JP-A-10-153967, JP-A-10-12377, or JP-A-11-40358.
In order for obtaining a higher-performance organic EL element, aggressive researches including development and improvement of materials, and proposition of various device structures are presently preformed.
Further, elements with various luminescent colors or high-intensity and high-efficiency elements have been developed as the organic EL elements, and various practical applications such as an application for pixels of a display device or an application for a light source have been studied.
And, various investigations are now in progress aiming for further improvement of luminous efficiency required for practical applications.

Light emitting element, display device and electronic instrument


A central electrode 12 is arranged in a coiled heater electrode 10. They are buried in a SnO2-based inner area 6, and the entirety is covered by a filter 8. The volume of the inner area 6 is set at from 1xc3x9710xe2x88x923 mm3 to 16xc3x9710xe2x88x923 mm3, the total volume of the bead 4 is set at from 15xc3x9710xe2x88x923 mm3 to 70xc3x9710xe2x88x923 mm3, and the ratio of the total volume of the bead 4 to the volume of the inner area 6 is set at from four to twenty to bring the sensor resistance in CO and that in methane closer to each other and increase the selectivity from hydrogen.

The present invention relates to improvement in a gas sensor having a coiled heater electrode.
A gas sensor is known wherein the surface of a metal oxide semiconductor having a coiled heater electrode is covered by a filter (for example, Japanese Patent Opening Hei 11-142356). Such a gas sensor is used, for example, by subjecting the gas sensor to periodical temperature changes, to detect CO at low temperature and a combustible gas, such as methane, at high temperature. As interfering gases, such as alcohol, can be easily removed with activated carbon filter or the like, the main interfering gas is hydrogen when CO is to be detected and when a combustible gas is to be detected. The resistance of the sensor in CO is generally higher than that of the sensor in a combustible gas, and this poses a problem in designing a detection circuit.
The objects of the present invention are
1) to bring the sensor resistance in CO and that in a combustible gas close to each other,
2) to improve the selectivity from hydrogen towards CO and combustible gases,
3) to increase the concentration dependency in the combustible gases, and
4) to decrease the concentration dependency in CO of low concentrations.
The present invention is a gas sensor wherein an inner area of SnO2 is provided to cover a coiled heater electrode and the inner area is covered by a filter, said gas sensor being characterized in
that the volume of the inner area is from 1xc3x9710xe2x88x923 mm3 to 16xc3x9710xe2x88x923 mm3
and that the ratio of the total volume of the inner area and the filter to the volume of the inner area is from four to twenty.
Preferably, the volume of the inner area is from 3xc3x9710xe2x88x923 mm3 to 10xc3x9710xe2x88x923 mm3, the ratio of the total volume of the inner area and the filter to the volume of the inner area is from four to fifteen, and the total volume of the inner area and the filter is from 15xc3x9710xe2x88x923 mm3 to 70xc3x9710xe2x88x923 mm3.
More preferably, the volume of the inner area is from 4xc3x9710xe2x88x923 mm3 to 10xc3x9710xe2x88x923 mm3, the ration of the total volume of the inner area and the filter to the volume of the inner area is from five to fifteen, and the total volume of the inner area and the filter is from 30xc3x9710xe2x88x923 mm3 to 60xc3x9710xe2x88x923 mm3.
Preferably, a central electrode is provided at the center of said heater electrode.
Preferably, both the filter and the inner area contain SnO2, the filter contains an aggregate, such as alumina, silica and zeolite, and the content of the aggregate in the filter is equal to or higher than that in the inner area. The content of the aggregate in the inner area may be zero.
Preferably, the concentration of a precious metal catalyst such as Pd and Pt, in the filter is lower than that in the inner area, and in the extreme case the filter may not contain any precious metal catalyst.
The present inventor examined how three factors, namely, the volume of the inner area, the total volume of the inner area and the filter, and the ratio of the total volume to the volume of the inner area, influence the characteristics of the gas sensor. The objectives were to bring the sensor resistance in CO and that in a combustible gas close to each other, to increase the selectivity from hydrogen towards CO and combustible gases, to increase the concentration dependency in combustible gases, and to decrease the concentration dependency in CO of low concentration (for example, from 100 ppm to 300 ppm). The concentration dependency in CO of low concentration is generally too high. For example, the resistance in CO of 300 ppm is 1/20 or lower of the resistance in CO of 100 ppm, and as the concentration dependency is too high, it is hard to design a driving and detecting circuit.
We have found that the volume of the inner area and the ratio of the total volume to the inner area influence the sensor characteristics at low temperature (characteristics for CO detection), and that the total volume influences the sensor characteristics for combustible gas detection. As for the inner volume and the volume ratio, when the volume of the inner area is small and the volume ratio is high, the resistance in CO is low and is closer to the resistance in the combustible gases, and the selectivity from hydrogen increases and the concentration dependency on CO at low concentrations decreases. On the basis of the values of these factors of the gas sensors produced on a trial basis, the volume of the inner area was set to be from 1xc3x9710xe2x88x923 mm3 to 16xc3x9710xe2x88x923 mm3, preferably from 3xc3x9710xe2x88x923 mm3 to 10xc3x9710xe2x88x923 mm3, and more preferably from 4xc3x9710xe2x88x923 mm3 to 10xc3x9710xe2x88x923 mm3. Similarly, the ratio of the total volume to the volume of the inner area was set to be from four to twenty, preferably from four to fifteen, and more preferably from five to fifteen.
The sensor characteristics in the combustible gases depend, as describe above, on the total volume. It was found that when the total volume is reduced, the sensor resistance in the combustible gas will decrease, but the selectivity from hydrogen will increase, the concentration dependency will increase, and at the same time the sensitivity to the combustible gases will increase. On the basis of these findings, the total volume was set to be from 15xc3x9710xe2x88x923 mm3 to 70xc3x9710xe2x88x923 mm3, and preferably from 30xc3x9710xe2x88x923 mm3 to 60xc3x9710xe2x88x923 mmxe2x88x923.


Circuits, methods, and apparatus for training a phase shift circuit to provide a phase shift for improved data recovery. A specific embodiment of the present invention provides a variable delay cell. A delay through the variable delay cell is changed while training patterns are received. The presence of errors in the received data pattern is tracked, and from the presence or absence of errors a preferred delay is selected and used for receiving data.

The present invention relates to high speed data interfaces in general, and more particularly to training a phase shift circuit used in a high speed interface.
In some high speed interface circuits, for example double data rate memory interfaces, a strobe signal is used for the timing and recovery of a number of data signals. That is, a transmitting circuit provides a number of data signals as well as a data strobe signal to a receiving circuit. This strobe signal may be transmitted such that its edges are aligned to edges or transitions of the data signals.
However, for proper data recovery, it is desirable for the strobe to be phase shifted relative to the received data, for example by ninety degrees. It is also desirable that this phase shift be done accurately to improve data recovery. It is further desirable that this shift be made automatically, for example at device power up or other appropriate time. By being made automatically, problems associated with manual adjustment, such as operator and other errors, are reduced or eliminated.
Thus, what is needed are circuits, methods, and apparatus for providing adjusting a phase shift in a high speed interface circuit. It is also desirable that this adjustment or training be performed automatically.

Data sampling clock edge placement training for high speed GPU-memory interface


An encoding method encodes, with an encoding device, second data made up of a plurality of first data representing predetermined numerical values. The encoding method includes taking a significant digit having, of the numerical values represented by each of the first data, the greatest absolute value, as a maximum significant digit of the first data. The encoding method also includes outputting, with the encoding device, code indicating the maximum significant digit and code indicating whether or not the maximum significant digit has changed. The encoding method additionally includes outputting code indicating the absolute value of a numerical value represented by the first data. Further, the encoding method includes outputting code indicating the sign of a numerical value represented by the first data.

JPEG (Joint Photographic Experts Group) 2000 is known as an encoding method wherein, in the event of performing image (data) encoding, coefficients of sub-bands (frequency bands) generated by performing band division processing on an input image are encoded.
In the event of encoding an image with JPEG 2000, wavelet coefficients obtained by performing wavelet transformation on the input image are quantized, and the quantized coefficients obtained by quantizing are further subjected to entropy encoding.
Conventionally, with entropy encoding, bit modeling called EBCOT (Embedded Block Coding with Optimized Truncation) and arithmetical encoding called MQ coder are performed. That is to say, quantized coefficients are subjected to bit modeling, and further subjected to arithmetical encoding based on multiple coding paths for each bit plane. The code obtained by the arithmetical encoding is output as an encoded image (data) (e.g., Patent Document 1).
Also, in the event of decoding an image encoded by JPEG 2000, processing is performed with procedures opposite to the case of encoding. More specifically, the code which is the encoded image data is subjected to entropy decoding an inverse quantization, and the quantized coefficients obtained thereby are further subjected to wavelet inverse transformation. The image obtained by the wavelet inverse transformation is output as a decoded image.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-166254

Encoding device and method, composite device and method, and transmission system


A surgical spatula has a planar transmission line for carrying microwave energy formed from a sheet of a first dielectric material which has first and second conductive layers on opposite sides thereof. The surgical spatula also has a coaxial cable for delivering microwave energy to the planar transmission line. The coaxial cable has an inner conductor, an outer conductor coaxial with the inner conductor and a second dielectric material separating the inner and outer conductors. The inner and outer conductors extend beyond the second dielectric to overlap opposite surfaces of the transmission line and electrically contact the first conductive layer and second conductive layer respectively. The width of the first and second conductive layers is selected to create an impedance match between the transmission line and the coaxial cable.

At certain frequencies, microwave energy can produce controlled ablation of biological tissue. For example, microwave energy having a frequency between 14 and 15 GHz has a relatively limited depth of penetration into biological tissue, which is beneficial for ablation control.
WO 2004/047659 and WO 2005/115235 disclose apparatus for and methods of both controllably ablating biological tissue and measuring information about tissue type and/or state using microwave radiation. These documents disclose the benefits of performing dynamic impedance matching between the energy source and the tissue.
WO 2008/044000 discloses a radiating scalpel suitable for use with the ablation apparatus mentioned above. The scalpel comprising an antenna arranged to emit a substantially uniform microwave radiation field along the cutting edge (i.e. blade) of the scalpel. The emitted microwave radiation is able to cauterise biological tissue during cutting, which facilitates invasive surgery performed on highly vascularised organs such as the liver.


A method for data processing is provided. The method includes obtaining first retrieving data associated with a first user and a first retrieving result selected by the first user from at least one retrieving result corresponding to the first retrieving data. The first retrieving data is labelled with an intention tag indicating a retrieving intention of the first user. The method further includes obtaining second retrieving data that is used by a second user to conduct retrieving and selecting the first retrieving result within a predetermined time period. The method further includes assigning the intention tag to the second retrieving data.

When a user conducts search or retrieving on the input retrieving data through a search engine, the intention recognition for these retrieving data may be used to analyze the user's retrieving requirements, such as looking for movies, novels, or encyclopedia knowledge and so on. Different requirements would lead to differences in terms of the underlying retrieving strategy. The intention recognition that is not correct may cause a failure for retrieving the contents that meet the user's requirements. Therefore, the accurate intention recognition is particularly important in practical applications.
Methods described in this section are not necessarily those previously envisaged or adopted. Unless otherwise specified, it should not be assumed that any method described in this section is considered the prior art only because it is included in this section. Similarly, unless otherwise specified, the issues raised in this section should not be considered to have been universally acknowledged in any prior art.

Method, apparatus, electronic device and storage medium for data processing

BEIJING BAIDU NETCOM SCIENCE TECHNOLOGY CO., LTD.


The present invention relates to integrating an inertial mechanical device on top of an IC substrate monolithically using IC-foundry compatible processes. The IC substrate is completed first using standard IC processes. A thick silicon layer is added on top of the IC substrate. A subsequent patterning step defines a mechanical structure for inertial sensing. Finally, the mechanical device is encapsulated by a thick insulating layer at the wafer level. Compared with the incumbent bulk or surface micromachined MEMS inertial sensors, vertically monolithically integrated inertial sensors provided by embodiments of the present invention have one or more of the following advantages: smaller chip size, lower parasitics, higher sensitivity, lower power, and lower cost.

Some embodiments of the present invention relates generally to monolithic techniques for micromachined technologies and integrated circuits. More particularly, some embodiments of the present invention provide a method and resulting device including both MEMS and integrated circuits using standard IC foundry-compatible processes. Merely by way of example, embodiments of the invention can be applied to resonators, oscillators, RF filters, sensors, and the like.
Micromachined resonators and filters have been proposed to replace conventional frequency devices such as a quartz crystal and a film bulk acoustic resonator, commonly called FBARs. Quartz crystals have been used for decades for providing a clock signal for small watches, computers, and almost any electronic or cellular phone application. Although successful, quartz crystals have limitations. That is, quartz crystal technology is often packaged in cumbersome enclosures, which lead to large form factors and the like, for conventional microelectronic applications. Quartz crystals are also limited to a single frequency, which also limits its applications and efficiency.
To overcome the limitations of crystals and FBAR devices, MEMS resonators and filters have been proposed. MEMS resonators are often fabricated in a similar way as integrated circuit (IC) chips and have significant reduction in form factor. In addition, MEMS resonators have superior performance, e.g. high Q factor, lower power, and lower cost comparing to the conventional counterparts. Furthermore, multiple frequency MEMS filters can be integrated on a single chip. Although somewhat successful, MEMS resonators and filters have drawbacks and limited penetration.
As an example, conventional MEMS resonator technologies are often based on MEMS fabrication processes such as bulk and surface micromachining techniques. Such bulk and surface micromachining techniques generally limit the level of integration of MEMS with other types of conventional devices. Additionally, conventional bulk surface and micromachining techniques are often expensive and difficult to scale up for true high volume production. These and other limitations may be described throughout the present specification and more particularly below.
Thus, it is desirable to improve MEMS resonators.
Moreover, as described below, it is desirable to have improved devices and methods in other monolithic techniques for micromachined technologies and integrated circuits. Some examples of these techniques can be used for improving MEMS device including pressure sensors, the stability of timing circuits, RF circuits, and the like, microneedle technology, as well as improved battery anode materials.

Method and structure of monolithically integrated IC-MEMS oscillator using IC foundry-compatible processes


A method of aligning flanges on two components to align and transfer torque from one component to the other uses a plurality of scallop regions on the periphery of a flange on one component; and a plurality of raised regions on the periphery of a flange on the other component, the raised regions being sized and shaped to engage the scallop regions on the flange when axially aligned to transfer torque there between.

When two v-band flanges are assembled together, such as the flange of a starter assembled to a gearbox, their relative clocking position is typically controlled using a pin in one flange and a hole in the other flange. The addition of a pin to one flange is performed by drilling a hole normal to the face of the flange and installing a pin. This pin is pressed into the flange and is retained by an interference fit with the flange. This interference fit results in tensile stresses in the flange which can reduce the life of the flange in high vibratory environments.
For example, flange-to-flange mating of starters to gearboxes of gas turbine engines is important because the starter imparts a high degree of vibration and torque, especially when the starter is hydraulic. Efforts to use pins and holes have not been found to survive high torque and vibration during use, such as with starter motors and gearboxes. The flanges mate, but because of stresses in the flanges and/or because of the pin or the hole, flanges may not survive adequately for operational use.


An automatic disarming device for use with self defense spray devices and other devices which have been taken from their owners or their normally stored position or location which renders such devices ineffective or inoperative until the devices are returned to their proper association with the disarming device or to their proper position. More specifically, the disarming device is adapted to but not limited to use with self defense spray devices as well as other useful or noxious spray devices when such devices are taken from their owners or from their proper place of storage thereby preventing such spray devices from being used against an owner or when such devices have been removed from a stored position by an unauthorized person or a person not familiar with appropriate procedures or precautions when actuating a spray device or other device.

1. Field of the Invention
The present invention relates to a method and apparatus for automatically disarming self defense spray devices and other devices which have been taken from their owners or their normally stored position or location which renders such devices ineffective or inoperative until the devices are returned to their proper association with the disarming device. More specifically, the disarming device is adapted to but not limited to use with self defense spray devices as well as other useful or noxious spray devices when such devices are taken from their owners or from their proper places of storage thereby preventing such spray devices from being used against an owner or when such devices have been removed from a stored position by an unauthorized person or a person not familiar with appropriate procedures or precautions when actuating a spray device or other device.
2. Description of the Prior Art
Many devices have been developed for use by law enforcement personnel or potential victims of violent crime. One of the more successful devices is the use of a pressurized container of noxious sprays or other spray dispensing devices which provides such persons with an effective means of nonlethal self defense when confronted by an assailant. Devices of this nature have been developed to discharge oleoresin capsicum, teargas, marking dyes, and a product available under the trademark "Mace", extract of the shell of the nutmeg nut or other disabling material with the spray material normally being available in a pressurized or aerosol type container or cartridge and usually released by actuating a nozzle and valve located at the top of the container. Containers with such spray material incorporated therein are frequently positioned within a shell or housing, sometimes in the form of a pistol grip type of shell, with a protective guard over the trigger to prevent accidental discharge of the material.
A well recognized problem associated with such devices is the possibility of an assailant gaining possession of the spray device by physical force with the spray device then being turned against the victim of the assault thereby incapacitating the rightful owner of the spray device. This problem has resulted in law enforcement officials and self defense experts not fully endorsing the use of such devices which has resulted in potential owners and users of such device being somewhat reticent to purchase and use self defense sprays.
The following U.S. Patents disclose devices which are somewhat relevant to the present invention.
U.S. Pat. Nos. 2,914,222 PA1 3,729,119 PA1 4,044,922 PA1 4,434,914 PA1 4,776,491 PA1 4,982,522
The above listed patents do not disclose an automatic disarming device of this invention in which the spray device or similar device is rendered ineffective and/or inoperative when such device is taken away from a rightful owner or removed from a stored position by an unauthorized person to prevent such a device being used.

Method and apparatus for automatically disarming self defense spray device


A system and method for selling services, experiences, and/or products over the Internet is presented. Customers may subscribe to a boutique product purchase feature that allows them to purchase limited offer products without proceeding through a check-out procedure. The method may include the steps of: (1) presenting the user with purchase options, (2) selecting a purchase option (3) presenting an order summary, (4) confirming the order, (5) charging an account, and (6) returning the user to a shopping page. Alternatively, the method may perform steps (1) though (5) without leaving the shopping page.

The Internet is a publically accessible global network that carries data through packet switching using the Internet Protocol (IP). A computer connected to the Internet can send and receive data from other computers that are also connected to the Internet, thereby allowing the computers to exchange information and provide services to each other, such as electronic mail, online chat, file transfer and web browsing. Web browsing, in particular, is widely used as a way to access information and services available through the Internet. Web browsing involves using an application program—called a browser—running on a first computer to retrieve data from a second computer over the Internet. The first computer is referred to as a client, while the second computer is referred to as a server. Typically, the server supplies the data and computer commands that make up a web site to the client computer in a process commonly referred to as hosting the web site. The browser interprets the data and commands retrieved from the server, causing the browser to display the data in such a way so that the user views it as a web page. Typically, the user will interact with the browser by entering keyboard, mouse, and/or other user interface commands, which causes the browser to load web pages and/or request that the server perform operations.
One Internet service that has become popular is retail sales. Internet retail sellers create virtual stores in the form of web sites that display their merchandise, and allow users to purchase goods, experiences, and services online. These goods, experiences, and services (collectively referred to herein as "products") may be in a form that can be delivered immediately over the Internet, such as digital media or software, or they may be in a form that requires shipment using conventional methods of delivery. Typically, a user visiting a retail sales web site will browse a collection of products displayed on a series of web pages, putting products which they are interested in into a virtual shopping cart, i.e., a personalized list of products marked for later purchase. When the user is finished shopping at the site, the user will proceed to a virtual checkout, where the user can purchase the products in their virtual shopping cart. In order to complete a purchase, a user will end the shopping experience by proceeding to a checkout web page, which is often served by a secure server that is separate from the server that provides product description pages.
Because of the convenience and cost savings associated with the Internet shopping experience, retail sales over the Internet have seen tremendous growth. In response to this demand, a large number of retail sales sites have emerged, and competition to provide a unique and compelling sales experience has created improved systems, methods and computer program products to serve this industry, and yet, a need for further improvements remains.

Method and system for selling products over a communications network


The invention relates to a motor vehicle roof with cover elements which are joined on each of their narrow sides to a pivotable attachment element which is guided along a guideway attached to the roof. Adjacent attachment elements are coupled for joint movement in the opening and closing direction so long as neither is in a fully swung-out position, and are decoupled, one by one as each of the adjacent attachment elements reaches its fully swung-out position. In the decoupled state, the adjacent attachment elements can be moved against one another as they are fully swung-out. An attachment element in the fully swung-out position is locked securely on the roof under the influence of the opening motion of an adjacent attachment element by a respective pivotable locking element, and is automatically released under the influence of the closing motion of the other adjacent attachment elements.

1. Field of the Invention
The invention is directed to a vehicle roof of the type with a series of plates for selectively closing and at least partially opening a roof opening in a fixed roof surface, the plates, in a closed position, bordering one another and forming a continuous panel of plates, each plate being slidably guided along a path of movement in a guide device that is connected with the fixed roof surface, on each lateral side of the roof opening, on a pair of guide elements which are spaced one forward of the other in a sliding direction, so that, when the plates are displaced along the guide device in an opening direction, the plates of the continuous panel of plates perform translational and pivoting movements during which the panel of plates is separated into individual plates in a plate-by-plate manner commencing with a rearmost plate of the plate system, the panel of plates being reestablished in a plate-by-plate manner commencing with a forwardmost plate when the plates are displaced along the guide device in a closing direction. In particular, the invention is directed to a vehicle roof of this type in which, in the decoupled state, the pivoted out plates can be moved against one another as each plate is fully swung-out, each fully swung-out plate being locked via an lock element securely to a guideway attached to the roof, and the locking of the fully swung-out plate to the guideway being automatically released under the influence of the closing motion of an adjacent attachment element.
2. Description of Related Art
A vehicle roof of the initially mentioned type is known from U.S. Pat. No. 5,484,185. This vehicle roof is a louvered, roof, and in contrast to sliding or sliding-lifting roofs, enables clearing of relatively large roof openings with simultaneous high stability, secure holding of the louvers, and an aerodynamically favorable behavior. Matching of the roof to different vehicle types can be achieved with relative ease. In the louvered roof known this patent, the lock for a fully swung-out louver is formed by an arrangement with a latch block in a bearing unit which joins two adjacent attachment elements at a time. Under the influence of the motion of the attachment element which is approaching the attachment element of the, current, last fully swung-out louver, a latch block slide, via sloped surfaces, exerts a transverse force on the latch block of the bearing unit which connects these two attachment elements perpendicularly to the opening direction of the vehicle roof so that the latch block is pushed perpendicularly to the opening direction into a latch block receiver in a guide rail attached to the roof, by which it causes locking of the bearing unit on the roof and thus of the fully swung-out louver. When the roof is closed, the reverse motion of the attachment element for the louver, preceding the, current, last fully swung-out louver, via sloped surfaces on the latch block and the latch block receiver, exerts a transverse force on the latch block such that the latch block moves out of the latch block receiver attached to the roof back into the latch block receiver in the latch block slide, and unlocking of the bearing unit (and thus the fully swung-out louver) from the roof.
In this known locking mechanism for a louvered roof, it has been found to be disadvantageous that installation is relatively expensive and the type of locking mechanisms, in practice, requires precise execution of the involved parts, especially the slide and the latch blocks, so that the respective bearing surfaces are made correspondingly small for transmission of force. As a results reliable operation of this known interlock mechanism is not always adequately ensured in practice, especially in series production In particular, the danger exists that the latch blocks will jam.

Motor vehicle roof with a series of raisable cover elements


A film forming method includes: forming a laminated film, in which an interface layer, a bulk layer, and a surface layer are laminated in this order, on a base; and crystallizing the laminated film, wherein the bulk layer is formed of a film that is easier to crystallize than the interface layer in crystallizing the laminated film, and wherein the surface layer is formed of a film that is easier to crystallize than the bulk layer in crystallizing the laminated film.

A polycrystalline silicon film may be used as a channel of a three-dimensional NAND structure. Patent Document 1 discloses a method of forming a polycrystalline silicon film by laminating, on a first amorphous silicon film in which crystals grow slowly, a second amorphous silicon film in which crystals grow faster than in the first amorphous silicon film, and then performing a crystallization process.

Film forming method and film forming apparatus


A DC/DC converter includes a main switching element and a subordinate switching element, and is arranged to supply power to load via a coil. The ON-time of a subordinate switching element in a succeeding cycle is controlled based on a period of time tdif from the time when the subordinate switching element is turned off until the time when voltage at the point of connection of the two switching elements reaches a predetermined threshold value.

A DC/DC converter is frequently used in applications for lowering or raising the output voltage of a DC power source to obtain a predetermined direct current output voltage, for example, a power circuit for a mobile phone. The DC/DC converter turns a switching element on/off, and controls the on/off period in this case, thereby converting a direct current input voltage into a predetermined direct current output voltage. MOSFET is generally used as the switching element.
This type of DC/DC converter has a coil. Thus, there is need to form a closed circuit for releasing electrical energy accumulated in the coil during the off-period of the switching element. Previously, the closed circuit was formed by a free-wheeling diode.
When the free-wheeling diode was used, however, its forward voltage drop was relatively great, thus posing the problem that power consumption at this portion aroused a decrease in the efficiency of the DC/DC converter.
Under these circumstances, a proposal has been made for a DC/DC converter which uses MOSFET being a switching element instead of the free-wheeling diode, and utilizes the switching function of the MOSFET itself to curtail the above-mentioned forward voltage drop. Incidentally, compared with the forward voltage of the free-wheeling diode, voltage loss due to the resistance of MOSFET in the ON-state is small, and power loss is diminished correspondingly.
Incidentally, in the DC/DC converter in which the freewheeling diode has been replaced by the switching element, two of the switching elements composed of MOSFET's are connected to each other in series. That is, the switching element for converting the output voltage to a desired value (hereinafter referred to as a main switching element), and the switching element for releasing energy accumulated in the coil during the OFF-period of the main switching element (hereinafter referred to as a subordinate switching element) are connected to each other in series A step-down DC/DC converter, for example, is constituted such that a direct current output voltage is withdrawn from the point of connection between both switching elements via the coil.
In this type of DC/DC converter, however, the following harmful phenomenon may arise: When, in a mode where the main switching element is in the OFF-state, and the subordinate switching element is in the ON-state, the subordinate switching element is switched to the OFF-state, an electric current based on the energy accumulated in the coil flows into the DC power source via a parasitic diode of the main switching element.
In order to avoid such a harmful phenomenon, in this type of DC/DC converter according to the prior art, it is common practice to monitor the coil current flowing through the subordinate switching element, detect a point in time at which the coil current becomes zero, and switch the subordinate switching element to the OFF-state at the time of the detection. This is because the harmful phenomenon occurs after the coil current becomes zero.
Thus, in the DC/DC converter according to the prior art, which has the main switching element and the subordinate switching element and turns these switching elements on/off alternately to obtain a predetermined direct current output voltage, a current detection circuit is provided in order to detect the above coil current (particularly, its direction). Such a current detection circuit can be realized, for example, by utilizing the ON-state resistance of the subordinate switching element, or by connecting in series a resistor for current detection, and comparing voltages at both ends of this resistor by a comparator for the purpose of monitoring. That is, when the voltage between both ends of the resistor has become zero, it can be detected that the coil current, which is the object to be detected, has become zero.
The following patent documents exist as publicly known documents disclosing DC/DC converters each of which has a main switching element and a subordinate switching element and turns these switching elements on/off alternately to obtain a predetermined direct current output voltage.
Patent Document 1: Japanese Utility Model Registration No. 2555245
Patent Document 2: Japanese Patent No. 3637904
The above-mentioned current detection circuit uses, as a current detection means, the current detection resistor of a very low value, or the ON-state resistance of the subordinate switching element. Thus, the level of the detected voltage is so low that the point in time at which the current has become zero needs to be detected promptly at a high speed and with high accuracy. Therefore, if the comparator is included as stated above, for example, it is necessary to use a comparator having a high speed and high accuracy. Not only is this comparator itself costly, but a high speed, high accuracy current detection circuit has to be constructed. A high drive current is required for the current detection circuit, and presents an impediment to downsizing or efficiency improvement of the DC/DC converter. If the resistor is included in series with the switching element as the current detection circuit, a power loss is caused by the resistor itself, becoming an obstacle to realization of high efficiency. Moreover, the level of the detection voltage is so low as to make a quick response difficult. Thus, actions may be rendered unstable by deviation due to offsetting of the comparator or a response delay. These are fatal drawbacks, particularly when the DC/DC converter is formed into an IC chi configuration.
The present invention has been accomplished in the light of the above-described conventional technologies. It is an object of the invention to provide a DC/DC converter which alternately turns on/off a main switching means and a subordinate switching means to obtain a desired direct current output voltage, which can eliminate a harmful phenomenon ascribed to the inversion of the polarity of a current flowing into a coil, and can also contribute to efficiency improvement, downsizing including IC chip formation, and cost reduction.