A code conversion method and apparatus is provided for scrambling and modulating data. The method and apparatus includes scrambling an input main data unit based on any of plural types of pseudo-random number sequences, and modulating the scrambled main data unit based on any of plural types of modulation data. An output main data unit is produced from the modulated main data unit, and a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the output main data unit is obtained. Any of the modulation data is then selected dependent upon the calculated value. The method and apparatus further includes determining whether or not a variation of the calculated value has exceeded a predetermined threshold, newly selecting another pseudo-random number sequence used for the step of scrambling if it is determined that the variation of the calculated value has exceeded the predetermined threshold value, and re-scrambling the input main data unit based on the newly selected pseudo-random number sequence.

1. Field of the Invention
The present invention relates to a code conversion method and apparatus for scrambling and modulating data, a code recording medium on which the scrambled and modulated data may be recorded and code recording and reproducing apparatus for recording/reproducing the scrambled and modulated data onto/from a recording medium.
2. Description of the Related Art
Optical disks have become very popular as recording media for recording various types of software data such as video data, audio data and computer data thereon. The optical disks include various kinds of read-only type disks such as a laser disk (LD), a compact disk (CD), a compact disk read-only memory (CD-ROM) and various kinds of rewritable and/or write-once type disks such as a magneto-optic disk, a phase change disk and a recordable compact disk (CD-R).
On the other hand, in recent years, high-efficiency coding technologies also have been developed. Consequently, any type of data currently can be processed as digital data. For example, even video data can be band compressed so as to be processed as digital data. In view of these developments, increasingly it has become necessary to further increase the capacity and the recording density of an optical disk.
However, as the recording density of a recording medium is increased, the difference between the signals representing a value of "1" and the signals representing a value of "0" which have been read out from such a recording medium becomes smaller. As a result, a read margin is adversely decreased and the quality of a reproduced signal is more likely to be degraded.
In order to avoid such a degradation in quality of a reproduced signal, the low frequency components of a signal must be reduced when the signal is recorded onto a recording medium. This is because a signal reproduced from an optical disk contains a lot of low frequency noise, which must be removed by a filter in order to improve the signal to noise (S/N) ratio of a reproduced signal. Thus, since the filter also cuts the necessary low frequency components of the reproduced signal, the effects of the noise reduction may be alleviated by preliminarily reducing the low frequency components of the signal to be recorded.
Various data coding methods have been proposed for reducing the low frequency components thereof. However, even when any of these coding methods is applied, a data pattern having low frequency components which cannot be reduced may still appear for a long duration in some cases. Thus, it is effective to scramble data for reducing the possibility.
When data is recorded and/or reproduced onto/from a recording medium, recording and reproducing operations are performed on the basis of a data unit having a particular size. Such a data unit is called a "sector". The run length of the codes recorded on a sector is limited in order to narrow the frequency bandwidth of a channel for the recording/reproducing apparatus.
Once an error is generated when the data is recorded and/or reproduced onto/from the run-length limited sector, the error does not remain in the erroneous sector but is propagated into succeeding sectors of the data. In order to prevent such error propagation, predetermined patterns identifiable from the recorded data are recorded onto every sector at regular intervals. Such patterns are called "sync codes". The respective regions of a sector which are partitioned by these sync codes are called "frames".
As mentioned above, since the low frequency components of data must be reduced when the data is recorded, the data is converted before the data is recorded. The conversion is accomplished, for example, by a code conversion apparatus such as that shown in FIG. 18.
As shown in FIG. 18, when main data is input to a scrambler 101, the scrambler 101 scrambles the main data in accordance with a pseudo-random number sequence and then supplies the scrambled main data to an 8/16 modulator 102. When the scrambled main data is input to the 8/16 modulator 102, the 8/16 modulator 102 modulates the main data and then outputs the modulated main data as recording data. The recording data is transmitted to a recording/reproducing apparatus to be recorded onto a recording medium.
In addition, the higher 4 bits (i.e., bit 4 to bit 8) of the logical address (8 bits) associated with the input main data is also input to the scrambler 101 as a seed select signal. Scramble data of different types are sequentially selected within a set of 16 logical addresses (i.e., on the basis of 16 sectors). That is to say, single scramble data is represented by any of respectively different 16 types of pseudo-random number sequences. Thus, in the respective sectors, the 16 types of pseudo-random number sequences associated with the respective scramble data are sequentially selected. Moreover, the scrambler 101 scrambles for data included in one sector depending upon the selected pseudo-random number sequences, in response to a sector start signal.
The scrambling is performed by the scrambler 101 by obtaining the exclusive-OR of the main data and the data (or random numbers) generated from an M sequence (maximum length sequence) represented by the following generating polynomial (1) for every bit of both types of data.X15+X4+1  (1)
FIG. 19 illustrates a configuration of the scrambler 101. As shown in FIG. 19, the initial bit patterns of the 16 types of pseudo-random number sequences are stored beforehand in a seed ROM 111. In response to a seed select signal, any of these initial bit patterns is selected from the seed ROM 111. A shift register 112 receives the initial bit pattern selected from the seed ROM 111 in response to a seed load signal and then sequentially shifts the initial bit pattern in synchronization with a bit clock. An exclusive-OR element 113 obtains an exclusive-OR of the bit shifted out by the shift register 112 and the fourth most significant bit stored in the shift register 112 and then returns the operation result to the shift register 112. The lower 8 bits stored in the shift register 112 are latched in a flip-flop 114 in synchronization with a word clock. A corresponding bit of the 8-bit string latched in the flip-flop 114 is applied to an individual exclusive-OR element 115. Not only the corresponding bit of the 8-bit string but also a corresponding bit of 8-bit main data word are input to each of these exclusive-OR elements 115, which obtains the exclusive-OR of each pair of bits and then outputs the operation result.
On the other hand, the 8/16 modulator 102 performs a two-stage modulation to produce an output main data from the scrambled main data. The first stage modulation is performed to produce 16-bit main data from 8-bit main data by modulating the scrambled data by means of a pit position modulation (PPM), while the second stage modulation is performed to produce 16-bit output main data from the 16-bit main data by modulating the 16-bit main data by means of a pulse width modulation (PWM).
FIG. 20 illustrates a configuration of the 8/16 modulator 102. As shown in FIG. 20, the 8-bit main data scrambled by the scrambler 101 is not only supplied to a main table 122 and a sub-table 123 via a flip-flop 121 but also directly supplied to a digital sum value (DSV) controller 124. The main data and data representing the next state as selected by a selector 125 are input to the main table 122. Similarly, the main data and the data representing the next state as selected by the selector 125 are input to the sub-table 123.
The main table 122 includes the main data shown in the following Table 1. An 8-bit main data value is searched for by state in the main table 122 and a 16-bit main data word corresponding to the next state is selected and output with reference to the main data shown in Table 1. Similarly, the sub-table 123 includes the sub-data shown in the following Table 2. An 8-bit main data value is searched for by state in the sub-table 123 and a 16-bit main data word corresponding to the next state is selected and output with reference to the sub-data shown in Table 2.
Since the range of the 8-bit main data values is from 0 to 255, 256 sets of 16-bit main data words are defined before-hand in the main table 122 for the respective 8-bit main data values (0 to 255). However, it should be noted that only a part (0 to 45) of the 8-bit main data values (0 to 255) and only a part of the 16-bit main data words corresponding to these 46 values are shown in Table 1. On the other hand, in the sub-table 123, 88 sets of 16-bit main data words are defined for a part (0 to 87) of the 8-bit main data values (0 to 255), unlike the main table 122. However, a smaller part (0 to 45) of the 88 8-bit main data values (0 to 87) and a smaller part of the 16-bit main data words corresponding to the 46 values are shown in Table 2. Furthermore, in both the tables 122 and 123, the next state is defined for each of the 16-bit main data words. Thus, when the 16-bit main data word is searched for, the next state corresponding to the 16-bit main data word is also read out.
TABLE 1Conversion table for 8/16 modulated codes(main)MainState 1State 2State 3State 4dataCode WordNextCode WordNextCode WordNextCode WordNextvalueMSB    LSBStateMSB    LSBStateMSB    LSBStateMSB    LSBState000100000000010011010000010010000020010000000001001101000001001000002100100000000100101001000000001001011000000100100000310000001001000003200100001001000002001000010010000021000000000010010110000000000100101300100000010010002010001001000000040010000001001000201000100100000004400100000100100002001000001001000021000000100100000210000001001000002500100000001001002001000000010010021001001000000000410010010000000004600100000001001003001000000010010031000100100000000410001001000000004700100000010010003010000000001001010010000001001000301000000000100101800100000100100003001000001001000031000010010000000410000100100000004900100001001000003001000010010000031001001000000001110010010000000011100010010010000000400100100100000004100010010000000111001001000000001111001000100100000040010001001000000410000000100100003100000001001000031200100100100000011001001001000000111000000010010000210000000100100002130010001001000001100100010010000011100001001000000111000010010000001114001000000100100110100000000100100300100000010010011010000000010010031500100001001000011001000100100000111000001001000001110000100010000011160010000010010001100100001001000011100000010010000111000000100100001117001000000010001010010000000100010110000010010000004100000100100000041800010000000010011010000001001000020001000000001001101000000100100002190010000000010001100100000000100011100100010000000041001000100000000420000100000001001010001000000010010110001000100000004100010001000000042100001000000000101000010000000001011000000010010001110000000100100011220000010000000001100000100000000011100000000100100111000000001001001123001000100010000020010001000100000210000000010010002100000000100100022400100001000100002001000010001000021000000001001000310000000010010003250010000010001000201000000001001002001000001000100020100000000100100226001000000100010020010000001000100210000000001000101100000000010001012700010001001000002000100010010000021000000000010001110000000000100011280010000000001000201000000100100003001000000000100020100000010010000329000100001001000020001000010010000210010010000000101100100100000001013000010000010010002010000010010000030001000001001000201000001001000003310001000000100100200010000001001002100100010000000111001000100000001132000100000000010020001000000000100210001001000000101100010010000001013300010000000001003000100000000010031000100010000001110001000100000011340001000000100100300010000001001003100000000010010021000000000100100235000100000100100030100001001000000400010000010010003010000100100000043600010000100100003000100001001000031000000000100100310000000001001003370001000100100000300010001001000003100001000100000041000010001000000438001000000000100030100100100000001100100000000010003010010010000000113900100000010001003001000000100010031001000010000000410010000100000004400010000010001000301000100100000011001000001000100030100010010000001141001000010001000030010000100010000310000100100000101100001001000001014200100010001000003001000100010000031000001000100000210000010001000002430010010001000000400100100010000004100001000100000111000010001000001144000100100100000040001001001000000410000010001000003100000100010000034500000010000000011010001000100000041000001001000010101000100010000004
TABLE 2Conversion table for 8/16 modulated codes(sub)MainState 1State 2State 3State 4dataCode WordNextCode WordNextCode WordNextCode WordNextvalueMSB    LSBStateMSB    LSBStateMSB    LSBStateMSB    LSBState000000100100000004000001001000000040100100001001000201001000010010002100001001000000004000010010000000040100100001001000301001000010010003200010010000000004000100100000000040100100000001001101001000000010011300000010010000004010001000000000111000001000000000401000100000000011400000001001000003010010000000001011001000000000100301001000000000101500000000100100003010000100000000041001000000100100301000010000000004600000000010010003010010000000010021001000001001000301001000000001002700000000010010002010000010000000041001000000000100201000001000000004800000000100100002010010001001000031001000000100100201001000100100003900000001001000002000010000010010021001000001001000201001000001001002100000010001000004000001000100000041001001001000000410010010010000004110000100010000000400001000100000004100010000100100031000100001001000312000100010000000040001000100000000401000100010010003010001000100100031300100010000000004001000100000000041000100000000100310001000000001003140000001000100000301001000000001003100100001001000030100100000000100315000000010001000030100100010010000210010001001000003010010001001000021600000000100010003010000100000000110100100000001000301000010000010011170000000001000100301000100000000101010010001000100030100010000000010118000000000100010020100100000100100310010000100100002010010000010010031900100000100010002010010010010000031001000100100000201001001000100003200000000100010000201001001001000002010001000100100020100100100100000221000000100010000020100100000010010101001000000010002010010000001001012200000100100000011000001001000000111000100000100100310001000001001003230000100100000001100001001000000011100010001001000031000100010010000324000100100000000110001001000000001101001000100010002010010001000100022500100100000000011001001000000000111000100000000100210001000000001002260010000001001001101000100000001003100001000000000110100100000000100327000000001001000110100000100000001110001000000000101010000010000000112800000001001000011010001000000010021001000000001001101000100000001002290000001001000001101000010000000101100100000001001010100001000000010130000100000100000040000100001000000410001000001001002100010000010010023100010000100000004000100001000000041000100001001000210001000010010002320001000100000000400100001000000004010001000000100110100100000001001133000001000010000030000010000100000301001000010010011010010000100100113400000010000100003010001000001001011000100100100000301000100000100101350000000100001000301001000000100011100100000000100030100100000010001136000000001000010030100000100000000410010000010001003010000001000000043700000100001000002000001000010000021000001000000001110000010000000011380000000010000100201000100001001003100010001001000020100010000100100339000000010000100020100010000100100210001001001000002010001000010010024000000010000100002010010000010001011001000000001000201001000001000101410000010001000001100000100010000011100001000000001011000010000000010142000001001000001010000010010000010110000001000000004100000010000000044300001000100000011000010001000000111001000001000100210010000010001002440000100100000010100001001000000101100100000000100111000100000001001145000100010000000110001000100000001110010000100010003100100001000100034600010010000000101000100100000001011001000100010000310010001000100003
In the main table 122, if an input 8-bit main data value is included within the range from 0 to 87, any of the four types of states S1 to S4 shown in Table 1 is selected in accordance with the next state specified by the selector 125. A 16-bit main data word corresponding to the input 8-bit main data value is selected from the 16-bit main data words belonging to the selected state. Then, the selected 16-bit main data word DM is output to a cross-bar switch 126.
On the other hand, if an input 8-bit main data value is included within the range from 88 to 255 in the main table 122 and any of the two types of states S1 and S4 shown in Table 1 is selected in accordance with the next state specified by the selector 125, a 16-bit main data word corresponding to the input 8-bit main data value is selected from the 16-bit main data words belonging to the selected state S1 or S4. Then, the selected 16-bit main data word D1 or D4 is output to the cross-bar switch 126. Furthermore, if an input 8-input main data value is included within the range from 88 to 255 in the main table 122 and any of the two types of states S2 and S3 shown in Table 1 is selected in accordance with the next state specified by the selector 125, a 16-bit main data word corresponding to the input 8-bit main data value is selected from the 16-bit main data words belonging to the selected state S2 or S3. Then, the selected 16-bit main data word is output to the cross-bar switch 126.
Similarly, if an input 8-bit main data value is included within the range from 0 to 87 in the sub-table 123, any of the four types of states S1 to S4 shown in Table 2 is selected in accordance with the next state specified by the selector 125. And a 16-bit main data word corresponding to the input 8-bit main data value is selected from the 16-bit main data words belonging to the selected state. Then, the selected 16-bit main data word DS is output to the cross-bar switch 126.
At this time, not only the selected 16-bit data words but also the next states corresponding to these 16-bit data words are read out from the tables 122 and 123 and then output to the cross-bar switch 126.
It is noted that the next state is initialized to be 1 in response to a sync code at the beginning of a frame.
When an 8-bit main data value and the next state specified by the selector 125 are input to the DSV controller 124, the DSV controller 124 makes a decision based on the 8-bit main data value and the next state and then outputs a cross-bar switch select signal corresponding to the decision result to the cross-bar switch 126.
In response to the cross-bar switch select signal, the cross-bar switch 126 selects one or two main data word(s) from the 16-bit main data word provided from the main table 122 and the 16-bit main data word provided from the sub-table 123 and then outputs the one or two 16-bit main data word(s) to at lest one of a first DSV arithmetic circuit 127 and a second DSV arithmetic circuit 128.
For example, if the DSV controller 124 has determined that the 8-bit main data value is equal to or smaller than 87 and the 16-bit main data word corresponding to the 8-bit main data value exists in each of the main table 122 and the sub-table 123, then the cross-bar switch 126 selects the 16-bit main data words DM and DS from the main table 122 and the sub-table 123, respectively, in response to the cross-bar switch select signal. Then, the cross-bar switch 126 outputs the 16-bit main data words DM and DS to the first and the second DSV arithmetic circuits 127 and 128.
On the other hand, if the DSV controller 124 has determined that the 8-bit main data value is equal to or larger than 88, the 16-bit main data word corresponding to the 8-bit main data value exists only in the main table 122, and either the state S1 or the state S4 has been selected by the next state specified by the selector 125, then the cross-bar switch 126 selects the 16-bit main data word D1 or D4 supplied from the main table 122 in response to the cross-bar switch select signal. Then, the cross-bar switch 126 outputs the 16-bit main data word D1 or D4 to the first and the second DSV arithmetic circuits 127 and 128.
Furthermore, if the DSV controller 124 has determined that the 8-bit main data value is equal to or larger than 88, the 16-bit main data word corresponding to the 8-bit main data value exists only in the main table 122, and either the state S2 or the state S3 has been selected by the next state specified by the selector 125, then the cross-bar switch 126 selects only a single 16-bit main data word (or the 16-bit main data word which has been read out in accordance with either the state S2 or the state S3 specified by the next state) supplied from the main table 122 in response to the cross-bar switch select signal. Then, the cross-bar switch 126 outputs the 16-bit main data word D2 or D3 to the first DSV arithmetic circuit 127.
The selections made by the cross-bar switch 126 from the 16-bit main data words DM, D1, D4 and DS are classified as shown in the following Table 3.
TABLE 3Main Data0 to 8788 to 25588 to 255ValueNextS1, S2, S3,S1 or S4S2 or S3StateS4DataSelect DM fromSelect D1 orAlwaysSelectionmain table andD4 correspond-select DMDS froming to S1 orspecified bysub-tableS4 from mainnext statetableS2 or S3from maintable
However, in the case where the 8-bit main data value is equal to or larger than 88 and either the state S1 or the state S4 has been selected in accordance with the next state specified by the selector 125, if the run length of successive codes having an equal sign between an 8-bit main data word and a previous 8-bit main data word is out of the range from 2 to 10 in either the state S1 or the state S4, then the DSV controller 124 controls the cross-bar switch 126 such that only a 16-bit main data word D1 or D4 belonging to the state S1 or S4 and having a run length within the range from 2 to 10 is selectively output. Thus, in order to output the 16-bit main data words D1 and D4 from the main table 122 to the first and the second DSV arithmetic circuits 127 and 128, the run length of the successive codes having an equal sign between an 8-bit main data word and a previous 8-bit main data word is required to be within the range of 2 to 10.
Every time a 16-bit main data word is input to the first arithmetic circuit 127 and/or the second arithmetic circuit 128, the arithmetic circuit(s) calculate(s) a digital sum value (DSV) associated with the input 16-bit main data word. The algorithm used for calculating the DSV is as follows.
For example, if a 16-bit main data word such as that shown in FIG. 21A is input from the cross-bar switch 126 to a PWM modulator 129 via the selector 125, the PWM modulator 129 performs a pulse width modulation on the 16-bit main data word, thereby producing and outputting a 16-bit output main data word such as that shown in FIG. 21B.
As can be seen from the comparison between FIGS. 21A and 21B, the number of "1" bits and the number of "0" bits included in a single output main data word can be derived from a single 16-bit input main data word. Thus, every time a single 16-bit main data word is input, the number of "1" bits and the number of "0" bits included in a single output main data word corresponding to the single 16-bit input main data word are obtained and then the difference between the numbers is calculated. The differences calculated for the respective words are accumulated, thereby obtaining a DSV. The DSVs calculated by the first and the second DSV arithmetic circuits 127 and 128 are supplied to the selector 125 and a comparator 130. In actuality, the "1" bit included in a single output main data word is replaced by a value "+1" and the "0" bit included in the single output main data word is replaced by a value "−1". The total sum of the values "+1" and "−1" is calculated in each output main data word. Then, the sums are accumulated for the respective words, thereby obtaining the DSV.
In addition, the calculation is performed by the first and the second DSV arithmetic circuits 127 and 128 on a sector basis, and is continuously performed from the beginning to the end of a single sector. At the beginning of a sector, the first bit (or the least significant bit LSB) of the sector is input from the PWM modulator 129 to the first and the second DSV arithmetic circuits 127 and 128 and the first value of the output main data word is initialized or set to be equal to zero in response to the bit LSB.
When the DSVs are input from the first and the second DSV arithmetic circuits 127 and 128 to the comparator 130, the comparator 130 selects either one of the DSVs having a smaller absolute value and then provides the information indicating the arithmetic circuit 127 or 128 which has calculated the selected DSV for the selector 125. In response to the information, the selector 125 selects the arithmetic circuit 127 or 128 indicated by the comparator 130, outputs the 16-bit output main data word from which the DSV has been calculated by the arithmetic circuit 127 or 128 to the PWM modulator 129, and outputs the next state associated with the 16-bit output main data word to the main table 122, the sub-table 123 and the DSV controller 124.
That is to say, in the 8/16 modulator 102, 8-bit input main data words are modulated into corresponding 16-bit main data words, the DSV of the respective output main data words corresponding to the 16-bit main data words is calculated beforehand, the 16-bit main data words, from which a smaller DSV can be derived, are selected and then the 16-bit main data words are modulated into the 16-bit output main data words so as to be output. However, as mentioned above, if the 16-bit main data word corresponding to the input 8-bit main data value exists only in the main table 122 and either the state S2 or the state S3 has been selected by the next state specified by the selector 125, then only a single 16-bit main data word (or the 16-bit main data word which has been read out in accordance with either the state S2 or the state S3 specified by the next state) is selected from the main table 122. Thus, the modulation from the 16-bit main data word to the 16-bit output main data word is performed.
A series of processing steps performed by such a code conversion apparatus will be described with reference to the flow charts shown in FIGS. 22 and 23.
First, after the top of a frame has been identified by counting the respective bits of an input main data word (Step 201), a sync code is added to the top of the frame (Step 202) and the next state output from the selector 125 of the 8/16 modulator 102 is initialized to be S1 (Step 203). Then, if it is determined that the end of a sector has not been reached (Step 204, NO), then the processing returns to Step 201.
Subsequently, the scrambling of the frame of the input main data word is started (Step 205) and the frame of the scrambled main data word is converted into the frame of an output main data word on a word basis (Step 206). Then, if the top of the next frame is identified (Step 201), a sync code is added to the top of the frame (Step 202) and the next state is initialized again to be S1 (Step 203). Next, the scrambling and the conversion are performed (Steps 205 and 206). From then on, similar processing is repeatedly performed on the respective frames. And when the end of a sector has been reached (Step 204, YES), the processing of one sector ends.
Moreover, after Step 206 has been performed, it is also determined whether or not the 8-bit main data value is smaller than 88. As shown in FIG. 23, if the value is smaller than 88 (Step 301, YES), then a 16-bit main data word having a smaller DSV is selected from the 16-bit main data word DM supplied from the main table 122 and the 16-bit main data word DS supplied from the sub-table 123 (Step 302).
On the other hand, if the 8-bit main data value is equal to or larger than 88 (Step 301, NO), then a 16-bit main data word D1 or D4 having a smaller DSV is selected from the main table 122 (Step 303).
If an output main data word always having a smaller DSV is produced in this manner, then the low frequency components of the main data word are reduced. Thus, in a recording/reproducing apparatus for recording and/or reproducing the main data word onto/from a recording medium, the low frequency components of a reproduced signal can be reduced, the shift of the envelope of the reproduced signal can be suppressed, and a reproduction error can be prevented to a certain degree.
However, though the above-described prior art code conversion apparatus can surely reduce the low frequency components of a reproduced signal and the possibility of the abnormal increase of the low frequency components, the degree of the reduction is not satisfactorily high and a reproduction error may continue to occur in some cases.
More specifically, when there are M types of 16-bit main data words in the 8/16 modulator 102 shown in FIG. 20. N types of 16-bit main data words having bit patterns causing the DSV to diverge are included in the M types of 16-bit main data words. Thus, if 16-bit main data words having such bit patterns successively appear, then the DSV adversely increases or decreases to diverge. As a result, the low frequency components of the output main data words are disadvantageously increased.
In the above-described conventional example, M=256 and N=168. When the 8-bit main data value is within the range from 0 to 87, the DSV converges. On the other hand, when the 8-bit main data value is in the range from 88 to 255, the DSV diverges. In actuality, the divergence of the DSV occurs in about 10% of the entire main data. FIG. 24A is a graph showing the variation of the 8-bit main data values in one sector and FIG. 24B is a graph showing the increase and the decrease of the DSV in accordance with the variation of the 8-bit main data values. As can be seen from these graphs, if the 8-bit main data values are continuously included within the range from 88 to 255, the DSV diverges.
That is to say, in the prior art code conversion apparatus, though the input main data is scrambled and the scrambled main data is subjected to an 8/16 modulation, the low frequency components of the main data cannot be satisfactorily reduced. Consequently, when the main data is reproduced from a recording medium on which the main data has been recorded, the low frequency components of the reproduced signal increase, the envelope of the reproduced signal abruptly varies, and a reproduction error occurs. Even if the envelope of the reproduced signal is corrected or the main data is corrected by using an error correction code (ECC) to be added thereto, such a reproduction error cannot be totally prevented.
In addition, since a set of pseudo-random number sequences are sequentially rearranged in a predetermined order, it is possible that substantially the same signal is repeatedly rewritten on the same sector. In such a case, since the characteristics of a part of the recording medium occupied by the sector in question become nonuniform, the S/N ratio of the reproduced signal is decreased and a reproduction error occurs in some cases.

Code conversion method and apparatus, code recording medium, code recording apparatus and code reproducing apparatus

Matsushita Electric Industrial Co., Ltd.


A force reversal value for an installed barrier is identified. The force reversal value is compared to a predetermined threshold. When the comparing indicates that the force reversal value exceeds the predetermined threshold, the operation of the moveable barrier operator is halted. A secondary safety device can then be installed and, responsive to the installing, the operator can be reenabled.

Different types of moveable barrier operators have been sold over the years and these systems have been used to actuate various types of moveable barriers. For example, garage door operators have been used to move garage doors and gate operators have been used to open and close gates.
Such barrier movement operators may include a wall control unit, which is connected to send signals to a head unit thereby causing the head unit to open and close the barrier. In addition, these operators often include a receiver unit at the head unit to receive wireless transmissions from a hand-held code transmitter or from a keypad transmitter, which may be affixed to the outside of the area closed by the barrier or other structure.
Movable barrier operator systems often include safety sensors or devices. These safety sensors are used to detect obstructions in the path of travel of the barrier to provide increased safety of operation. Previous systems are programmed to react differently when the safety sensors are not attached. In some of these systems, the sensors must be detected by the operator before travel of the barrier is allowed.
In some situations, both primary and secondary safety sensors are used. For example, a primary sensor may determine when to reverse movement of the barrier and a secondary safety sensor used to verify the accuracy of the reading of the primary safety sensor. In some instances, the use of a secondary safety sensor is required.
Different countries have different standards with regards to requiring the use of secondary safety sensors. For example, some European standards require that an operator and barrier combination be tested to determine the force impacted on a strain gage that would cause a reversal of the movement of the barrier. If the force exceeds a threshold, then a secondary safety sensor is required to be installed. Unfortunately, using this approach, testing is required upon potentially every installation of a barrier operator. Since a test may need to be performed upon every installation, product cost, delays, and user frustration increase.

System and method for automatically requiring secondary safety sensors


A riflescope. In the illustrative embodiment, the inventive riflescope is implemented with a housing having an exterior surface and a texture applied to the surface of the housing. In the best mode, the texture has an elevation of 250 microns above the surface of the housing. In more specific embodiments, the texture is uniform and geometric.

1. Field of the Invention
The present invention relates to firearms. More specifically, the present invention relates to riflescopes.
2. Description of the Related Art
Telescopes are used on some rifles to improve the long-range accuracy thereof. For certain applications, especially military applications, there is often a need to minimize reflection from the rifle including any 'scope' that may be mounted thereon. Indeed, in military circles, it is well known that a single reflection may reveal a soldier's position and put the soldier and his unit in jeopardy.
Hence, a common practice is to apply a matte or crinkle finish to the scope. A conventional matte finish is less than 20 microns deep and is applied by sandblasting.
Unfortunately, over time, these finishes are often worn off by the rugged environment in which the rifle is transported and used. Consequently, areas of relatively high reflectivity often appear on rifles scopes matted in accordance with conventional teachings.
Accordingly, a need remains in the art for a system or method for minimizing reflections from riflescopes.


Glass vessels are coated by spraying a solution containing 100 to 1,000 g/L of (OH).sub.2 SnCl.sub.2 on the 500.degree. to 600.degree. C. hot outer surface of the glass vessels. The solution may contain oxalic acid and a portion of the (OH).sub.2 SnCl.sub.2 compound may be substituted by a compound (HO).sub.x Sn(C.sub.2 O.sub.4).sub.y, wherein y is 0.2 to 3.8, y is 1.9 to 0.1 and (2y+x)=4. The coatings are uniform.

It is known to coat thin tin oxide layers on glass surfaces by exposing the heated glass to a vaporized tin compound. The tin compound may be applied as a vapor or as a fine spray which contains a dissolved tin compound.
For example, U.S. Pat. No. 3,414,429 discloses a method for applying metal oxide layers on glass containers, wherein tin(IV) halides, such as tin tetrachloride, are used as tin compounds. However, these compounds hydrolyse readily in the presence of mere traces of moisture with the formation of highly corrosive compounds. Since only a small portion of the tin halides introduced into the coating chamber is actually deposited on the glass surface and the unused portion of the tin halides cannot be recycled without considerable expenditure, the tin halides have only a limited suitability for coating or surface improving glass. Since tin tetrachloride, when used, is generally stabilized with additional hydrogen chloride, at least four chloride atoms per tin atom are obtained, which contaminate the effluent or waste water in the form of the chlorides. Moreover, because of spontaneous decomposition of tin tetrachloride, it is not unusual that a nonuniform build-up of the tin oxide layer takes place which results in optically confusing interferences.
If tin dichloride is used instead of tin tetrachloride, the amount of chloride to be disposed of is theoretically reduced. However, because of the hydrolytic instability of the aqueous solutions of tin dichloride, also in this instance hydrogen chloride has to be added to these solutions. As a result, the amount of chloride rises again above the value of 1 Sn : 2 Cl. In addition, the problem of the increased corrosion of the equipment by the hydrochloric acid-containing tin dichloride solution remains.
German Patent 25 41 710 discloses a method for applying a tin(IV) oxide layer on a glass container by the pyrolysis of a vaporized or finely divided, liquid tin compound on the surface of glass having a temperature of 450.degree. to 600.degree. C. For this method, a monoorgano tin trichloride of the general formula RSnCl.sub.3, wherein R is an alkyl radical with 1 to 8 carbon atoms, is used as tin compound. Preferably, butyl tin trichloride is used as monoalkyl tin trichloride. However, organo tin compounds are toxic products, which must be identified as such and the use of which requires special care. With respect to pollutant emission, it is a disadvantage that three chlorine atoms per tin atom are released and must be disposed of.
The glass containers provided with a tin(IV) oxide layer (hot end coated) can subsequently be additionally provided with a thin film of a natural wax or a synthetic polymer (cold end coating). Such a coating usually is transparent and makes the glass container even more resistant to scratching and abrasion, even when said container comes into contact with alkaline cleaning agents.

Preparation and method for coating glass vessels


Methods of forming a component of a thin film magnetic head and improving the plating of a component of a thin film magnetic head are provided. The methods include the use of a high activation energy chemically amplified photoresist (CARS) that is contacted with a low pH high saturation magnetic moment plating solution to form a magnetic head component that is essentially free of plating defects. The methods find utility in hard disk drive applications, such as in the manufacture of magnetic poles for the write head of a hard disk drive.

The need for increased storage capacity and improved read and write access to information stored on magnetic disk drives has produced a large number of improvements in hard disk drive technology. The general trend has been toward increased areal density of information stored on magnetic disk drives, accomplished in part by improvements in the magnetic storage characteristics of materials used to store magnetic information on hard disks and by improved designs and methods of making read and write heads for hard disks. In a thin film write (recording) head, for example, such improvements have resulted in reductions in the width of the pole tips of the write heads in order to increase the track density of the recording medium to which the head writes information. Since higher track densities resulting from narrower pole tip widths allow for more information to be stored on a hard disk, the need to provide further improvements by reducing track width presents a continuing challenge.
Write heads for hard disk drives also desirably benefit from the use of high magnetic fields for writing information on a hard disk. In order for a high magnetic field to be provided by a write head, the magnetic flux density needs to be high in the write head. In turn, higher saturation magnetic moments for write heads are necessary to provide higher flux densities so that areal densities of the magnetic media may thereby also be increased. Materials with high saturation magnetic moments allow for the generation of higher magnetic fields in the magnetic media, increased field gradients, faster effective rise times, narrower pulse widths, smaller erase bands and improved over-write characteristics on the magnetic media. For this reason, it is desirable that the pole tips of a thin film magnetic write head be formed from a high saturation magnetic moment material.
The fabrication of a thin film magnetic head, as well as the various components of the magnetic head, requires that certain submicrometer structures be formed. An example of such a structure is the pole tip of a write head. One method of making pole structures is to fabricate a mask using a photoresist according to a frame plating method in conjunction with a plating process. A typical general sequence for frame plating a pole structure includes depositing a seedlayer on a wafer, spin coating a layer of photoresist on the wafer, imagewise patterning of the photoresist through a mask to expose areas of the photoresist intended to be removed (for a positive-tone resist, or areas intended to be not removed for a negative-tone resist), removal of areas intended to be removed by developing the photoresist to thereby provide a framed opening in the photoresist corresponding to a pole structure, and plating the framed opening to form the pole structure by a conventional plating process.
Resist frame plating methods are also described in the literature. In U.S. Pat. No. 6,547,975 (to Kobrin), for example, a magnetic pole fabrication process is described in which a seedlayer material is sputtered onto the vertical sidewall portion of a polymer layer used to form a submicrometer structure. A "resist frame for plating" method is also referred to in Kobrin based on the disclosure of U.S. Pat. No. 5,665,251.
In U.S. Pat. Nos. 6,635,408 and 6,641,984 and U.S. Patent Application Publication No. 2001/0035343 (all to Kamijima) and U.S. Pat. No. 6,358,674 (to Kamijima et al.), frame plating methods are also described using a resist that may be a chemically amplified resist. The resist is described as being coated with a covering layer of a water-soluble crosslinking agent capable of being crosslinked in the presence of acid and a resin material containing at least a water-soluble resin on the water-soluble crosslinking agent. The covering layer, rather than the resist, appears to be described as functioning as the frame in contact with the plating solution.
As is known in the art, chemically amplified resists (CARS) may be categorized as positive-tone or negative-tone resists. Positive-tone resists generally contain two major components: an aqueous base soluble polymer resin and a photoacid generator (PAG). The aqueous base soluble polymer of such chemically amplified resists typically contains polar functional groups protected by acid-cleavable protecting groups (also known in the art as acid labile, or blocking groups). The presence of such protecting groups converts the aqueous base soluble polymer into an insoluble resin. Acid catalyzed deprotection of the protected sites converts the polymer back into an aqueous base soluble polymer. Development of the positive-tone resist selectively removes the exposed regions of the photoresist.
The acid-cleavable groups used with the aqueous base soluble polymer resins can be classified into two distinct groups: a) high activation energy protecting groups such as t-butyl ester or t-butyl carbonyl groups; and b) low activation energy protecting groups such as acetal, ketal or silylether groups. Hybrid resists are also described in the art in which a combination of high and low activation energy groups is included in the resist (see, e.g., U.S. Pat. No. 6,303,263 to Chen et al.).
Although a wide variety of photoresists are known in the art, the requirements of a specific application may govern the suitability of using a particular resist in that application. For example, in contacting a resist frame with certain plating process solutions, defects such as cracks and "worms" (i.e., localized fractures or irregular defects in the resist) may be introduced into the resist depending on the type of resist, the plating solution and/or the plating conditions used. Such defects, in turn, may lead to irregularities and defects in the plated structures obtained from the plating process.
Thus it is desirable to have a method for making plated components for hard disk drive magnetic heads, particularly the write head poles of a magnetic head, which are essentially free of plating defects. It is further desirable for such a method to provide a means for reducing or eliminating such defects through compatible modifications to existing methods for making plated components for magnetic heads.
Accordingly, the present invention addresses such needs in part by providing an improved method of forming a component of a magnetic head, that, in one embodiment, is suitable for making a plated magnetic component of a write head for use in a hard disk drive.

Elimination of write head plating defects using high activation chemically amplified resist

Hitachi Global Storage Technologies Netherlands B.V.


The present invention has an object to reduce a thickness of a protecting film having a small thermal conductivity. A thermal head includes: a plurality of heat generating resistors formed via an insulating layer; a driver circuit unit for driving the plurality of heat generating resistors to generate a heat; a wiring for connecting the driver circuit unit to the plurality of heat generating resistors; a protecting film formed to cover the plurality of heat generating resistors, the driver circuit unit and the wiring, wherein the plurality of heat generating resistors, the driver circuit unit, the wiring 11 and the protecting film are formed on a substrate, and wherein a thermal conductor having a thermal conductivity larger than that of the protecting film is disposed on the protecting film, in opposition to each of the plurality of heat generating resistors.

1. Field of the Invention
The present invention relates to a thermal head and a thermal printer, and more particularly to a thermal head and a thermal printer using a single crystalline silicon substrate.
2. Description of the Related Art
In recent years, thermal heads for performing thermosensitive recording by selective heat generation of a heat generating element have been used.
Japanese Patent Application Laid-Open No. H02-137943 discloses a thermal head using a single crystalline silicon substrate.
The thermal head disclosed in Japanese Patent Application Laid-Open No. H02-137943 includes: a heat generating element formed on a single crystalline silicon substrate via an insulating film; a driver circuit unit formed on the single crystalline silicon substrate; a wiring layer for connecting the driver circuit unit to the heat generating element; and a protecting film for protecting a thermal head surface.
The protecting film contacts a printing medium such as an ink sheet and thus requires abrasion resistance, and is formed of a hard insulating layer of SiO2, Si3N4, SiON or Ta2O5 having a thickness of several μm.
The insulating film used as the protecting film in Japanese Patent Application Laid-Open No. H02-137943 has a small thermal conductivity, and for example, SiO2 has a thermal conductivity of 0.9 W/m·K, and Si3N4 has a thermal conductivity of 16 W/m·K.
The insulating film has the large thickness of several μm for providing abrasion resistance, and thus it takes a long time for heat generated by the heat generating element to transfer to the printing medium to increase a printing time.
An insulating film between the heat generating element and the silicon substrate has an equal thermal conductivity to that of the protecting film, but has a thickness of around 1 μm smaller than that of the protecting film.
Further, the silicon substrate has a large thermal conductivity of 152 W/m·K, and thus thermal energy generated by the heat generating element easily escapes toward a heat sink to cause a large loss of the thermal energy.
The present invention has an object to reduce a thickness of a protecting film having a small thermal conductivity.


Disclosed are a shift register, gate electrode driving circuit, display panel and display device. The shift register includes a second output module and a coupling module, the coupling module having two ends electrically connected to a third node and a second signal output end respectively. In a second phase, a potential at a fourth node is an enable level, the second output module transfers a high-level signal at a first power source signal input end to a second output end; in a third phase, a potential at the third node is the enable level, the second output module transfers a low-level signal at a second power source signal input end to the second output end; the low-level signal at the second output end is coupled to the third node through a coupling function of the coupling module, the potential at the third node is then lower in the third phase than in the second phase.

With the development of display technologies, higher definition is pursued for display devices, however power consumption of the display devices is increasing. In order to reduce power consumption of a display device, in a certain duration, a frame rate may be reduced and pixels may be driven at a low speed. For example, a mobile terminal works at a normal driving frequency of 60 Hz or 120 Hz in a normal display mode but works at a driving frequency of 1 Hz to 5 Hz in a standby mode.
In general, in order to ensure stable display, the pixel driving circuit of a display device may be designed to use P-channel Metal Oxide Semiconductor Field Effect-Transistors (PMOSFETs). However, since the PMOS formed of Low Temperature Poly-Silicon (LTPS) has a large leakage current, data updating period will lasts longer while driven at a low frame rate. When a leakage current exists in a pixel, a flicker will occur at that pixel for a displayed image, so the image cannot be displayed normally. Therefore, some PMOSFETs in the pixel driving circuit may be substituted by N-channel Metal Oxide Semiconductor Field Effect-Transistors (NMOSFETs); however, a traditional shift register uses PMOS shift, in which high-level (herein "level" may also be called "potential") shifting includes "step-down", i.e., a high level is converted into a low level via an intermediate level, and the high level can hardly be shifted effectively, i.e., the cascade shifting of high-level and low-level signals cannot be implemented without loss. Meanwhile, a transistor cannot be turned off completely (i.e., "cut-off") under the control of a control end, and the leakage current still exists, affecting display effect.

Shift register, gate driving circuit, display panel and display device


A fitment adapted to cover and reinforce an exposed edge of a container and facilitate the loading of the container with material. Alternatively, the fitment may be integrally formed with the container to be filled. The fitment includes a generally planar surface having a peripheral edge and an apertured cover hingedly attached thereto. A loading ledge, able to support heavy material to be loaded, is provided when the apertured cover is in the open position. The peripheral edge further includes a ramped portion to support the opened cover and heavy material. Apertures in the fitment allow passage of material from the ledge into the container.

The present invention relates generally to support surfaces for loading a material or composition of materials into a container or for resting a material or composition of materials on a container so that they may be easily sorted or more easily transferred and/or deposited into the container. The invention more particularly relates to a fitment adapted to receive and support a load, e.g., a heavy bag or other container, during loading or transfer of material into the container proper.
The invention is believed to have application to all situations where it would be beneficial to rest the material to be placed into a container prior to placement in the container. Examples of such situations include, but are not limited to heavy loads of aggregate material that are to be measured into the container, loads of material that are to be sorted, fill and/or transfer prior to placement or deposit in the container or material that is to be mixed. Specifically, but not by way of limitation or exclusion of other applications, the present invention has application with containers like brine tanks. Some containers, such as brine tanks for regenerating the material used in water softeners, are periodically loaded with material, such as bagged rock salt crystal or pellets, that must be lifted from a lower level to the level of the container opening. This task is often difficult and cumbersome because of the weight of the material. The container walls are easily buckled during loading as the person loading rests the material-containing bag on the container opening edge.
The present invention specifically addresses and alleviates the above-noted problems associated with filling a container with heavy or cumbersome material as well as any load that may be temporarily rested prior to being transferred into a container. More particularly, a loader ledge fitment for water softener containers and the like is disclosed, which comprises an outer periphery configured to receive and fit over at least one portion of the container opening. Alternatively, the fitment may be integrally formed with the container to be loaded. The loader ledge provides a perforated cover through which the material may be poured, and a hinged cover which, while in the open position, provides a ledge for resting the material while being deposited. After the material (for example softener salt in the case of a water softener) has been poured into the container, the hinged ledge is rotated to the closed position. Further, the conventional lid supplied by the container manufacturer may be used in conjunction with the present loader ledge fitment when the container is not being loaded.
Alternatively the present invention may be summarized as a fitment for use with or integrally formed with a container for receiving a load of material comprising a supporting perforate or imperforate web and opening. The fitment having a shape substantially conforming to a contour of the container with which the fitment is to be used. The supporting web being circumjacent to the opening and including a ramp structure having a downward slope extending toward the opening. The supporting web including a surface for supporting the load of material. Whereby the load of material may be placed on the surface and a predetermined portion of the load of material may be transferred through the opening into the container.
Additionally the fitment may further include at least one channel having curb structures and the container may include at least one edge structure having a predetermined shape. The channel may substantially conform to the predetermined shape of the edge structure and extend along and engage a predetermined portion of the edge structure. The fitment may also include at least one bracket structure having at least a first end removably engagable with an exterior surface of the container and at least a second end coupled to the supporting web. The fitment may also include a bracket structure having at least one lockable collapsible lever mechanism.
In another alternative embodiment the fitment may include a supporting web, an opening, and a channel for use in combination with a container having at least one open end including at least one edge structure. The channel in this embodiment is engagable with the edge structure and the fitment includes a slot having an opening. The supporting web is capable of being extended and retracted through the slot so that when the supporting web is extended through the slot the opening is presented.
Additionally, the supporting web may have a retracted position and an edge and the fitment may include an inner wall and the container edge is capable of abutting the inner wall. Further, the supporting web may include a key structure and the opening may include at least one edge capable of engaging the key structure. Additionally, the supporting web may include at least one opening.
Another alternative of the present invention may be described as a fitment for use with a container for receiving a load of material, the fitment including a supporting web, a hinge structure and a channel. The container having at least one open end including at least one edge structure. The channel is engagable with the edge structure and the fitment is hingedly coupled to the supporting web at the hinge structure. The supporting web includes a stop structure and the fitment includes an abutment structure. The stop structure is engagable with the abutment structure such that engagement of the stop structure with the abutment structure places the supporting web in position to receive a load. Further, the fitment may be integral to the edge of the container.
In another alternative embodiment the present invention may be summarized as a fitment for use with a container for receiving a load of material, the fitment comprising a supporting web, a slot, a hinge mechanism and a channel. The container having at least one open end including at least one edge structure. The channel engagable with the edge structure. The fitment including a slot. The supporting web rotatably coupled to the fitment at the hinge mechanism. The slot having sufficient size and spatially orientation so that the supporting web may be rotated on the hinge mechanism and extended out of the slot and retracted back through slot. Whereby when the supporting web is extended through the slot the opening is presented and when the supporting web is retracted through the slot the open end is closed and the container is covered.
Further, the supporting web may include an opening spatially orientated on the supporting web so that a user may grasp the opening to aid in extending the supporting web through the slot. Also, the fitment may be integral to the edge of the container.
Another alternative embodiment of the present invention may be summarized as including a fitment for use with a container for receiving a load of material, the fitment comprising a supporting web surface and a channel. The container having at least one open end including at least one edge structure. The channel engagable with at least one portion of the edge structure. The channel located on a first fitment surface substantially opposite the supporting web surface.
Further, the channel may include a plurality of curb structures having a predetermined pitch and which are spatially orientated to impart a predetermined angle to the channel. Accordingly, the fitment may be removed from covering the container and the channel may be engaged with at least one portion of the edge so that the supporting web surface and at least a portion of the open end are presented for receiving the load of material.
Another alternative embodiment of the present invention may be summarized as a fitment for use with a container for receiving a load of material with the fitment comprising a hinge structure, a bearing pin structure, a supporting web surface, a bracket, and a channel. The container having at least one open end including at least one edge structure. The bearing pin structure mounted to the container. The channel engagable with at least one portion of the edge structure. The channel located on a first fitment surface substantially opposite the supporting web surface. The fitment including an inside rim surface. The container includes an inside surface. A lockable collapsible bracket coupled to the inside rim surface at the hinge structure and to the container at the bearing pin structure. The bearing pin structure slidably engaged with the bracket. The fitment pivotally coupled to the bracket at hinge structure. Accordingly, in this embodiment the fitment may be lifted off of the edge of the container until the bearing pin structure engages a distal end stop structure of the bracket.
Alternatively, the present invention may be generally summarized as a method of transferring a material into a first container from a second container, and wherein the material and its second container is lifted or placed from a lower level to the opening level of the first container. The method comprising the steps of:
Providing the first container with an open end including an edge structure.
Hingedly attaching an apertured cover to the edge.
Rotating the hingedly attached cover between a closed position and an opened position relative to the opening.
Lifting the second container and the material contained therein from the the lower level to rest upon the opened cover and transferring the material into first container.
The method could also include the step of providing a ramped surface extending from the hingedly attached cover. Additionally, the method could include the step of resting the opened cover on the ramped surface.


Systems and methods of design, delivery, and analysis of customer feedback surveys include receiving interaction content. Interaction content is analyzed to identify at least one issue arising in the interaction content. A survey of a plurality of questions is automatedly created based upon the identified at least one issue. A delivery channel for the survey is determined. The survey is delivered through the determined delivery channel. A survey response with survey results data is received.

The present disclosure is related to the field of speech analytics. More specifically, the present disclosure is related to the automated generation and analysis of surveys based upon analysis of communication data.
Surveys are used in order to solicit customer feedback regarding various aspects of a customer experience or perceptions of an organization. Such surveys can be sent to customers in a variety of platforms, including, but not limited to telephonic, paper, Internet based, or email surveys.
Embodiments disclosed herein leverage insights gained from analysis and processing of customer service interactions in order to present surveys to customers that may achieve a higher response rate and produce more meaningful results for an organization.
Customers response rates to surveys typically decrease as the number and complexity of the questions increases. Therefore, typically, surveys constructed to promote response rates include only a limited number of questions. This presents a problem as customer identification, demographic, or other contextual information must be solicited in the customer survey in order for the topical questions directed to specific issues to be meaningfully analyzed. However, the need for the contextual questions decreases the number of available topic or issue questions that may be asked while still attempting to promote response rate. Furthermore, generically constructed surveys may ask customers regarding unrelated or irrelevant questions relative to the customer's experience. This not only reduces response rate, but can bring decrease the value of any responses received should the customer reply.


A free magnetic layer has a laminated structure in which a first magnetic sublayer composed of Co—Fe or Fe and a second magnetic sublayer composed of Co—Fe—B or Fe—B are formed, in that order, on an insulating barrier layer composed of Mg—O. This effectively improves the rate of change in resistance (ΔR/R) compared with the related art.

1. Field of Invention
The present invention relates to tunneling magnetic sensing elements including an insulating barrier layer composed of Mg—O. In particular, the present invention relates to a tunneling magnetic sensing element having an effectively improved rate of change in resistance (ΔR/R) compared with that in the related art, and a method for producing the tunneling magnetic sensing element.
2. Description of the Related Art
Tunneling magnetic sensing elements (tunneling magnetoresistive (TMR) elements) exhibits a change in resistance due to the tunneling effect. When the magnetization direction of a pinned magnetic layer is antiparallel to that of a free magnetic layer, a tunneling current does not flow easily through an insulating barrier layer (tunnel barrier layer) between the pinned magnetic layer and the free magnetic layer; hence, the resistance is maximized. On the other hand, when the magnetization direction of the pinned magnetic layer is parallel to that of the free magnetic layer, the tunneling current flows easily; hence, the resistance is minimized.
A change in electrical resistance due to a change in the magnetization of the free magnetic layer affected by an external magnetic field is detected as a change in voltage on the basis of this principle to detect a leakage field from a recording medium.
Japanese Unexamined Patent Application Publication Nos. 2004-179667, 2002-141583, and 2005-197764 are examples of the related art.
Changing the material of the insulating barrier layer changes characteristics, such as the rate of change in resistance (ΔR/R). Thus, studies have been conducted on insulating barrier layer materials.
For example, in the case of an insulating barrier layer composed of Mg—O, a free magnetic layer has been used, which has a laminated structure with a NiFe sublayer and a CoFe sublayer that is located between the NiFe sublayer and the insulating barrier layer
In the above-described structure, however, a sufficient rate of change in resistance (ΔR/R) has not been obtained. To achieve higher recording density, further improvement in the rate of change in resistance (ΔR/R) has been required.

Tunneling magnetic sensing element and method for producing same


Compounds having the formula ##STR1## or a pharmaceutically acceptable salt thereof wherein Y is selected from halogen, alkyl, and haloalkyl; n is 0, 1, 2, or 3; X is absent or is alkylene; A is absent or is selected from optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted cycloalkylene wherein one or two of the carbon atoms is replaced with one or two heteroatoms independently selected from O, S, and N, optionally substituted alkenylene, and ##STR2## or R.sup.2 and A together define a saturated 5- to 8-membered optionally substituted carbocyclic or heterocyclic ring to which the group Z is attached; Z is selected from (a) hydrogen, (b) COM wherein M is selected from the group consisting of --OR.sup.5, a pharmaceutically acceptable cation, --NR.sup.7 R.sup.8, and a pharmaceutically acceptable, metabolically cleavable group, (c) --OR.sup.3, (d) tetrazolyl, (e) --CH(OR.sup.3)--CH.sub.2 OR.sup.9, (f) --CH(OR.sup.3)--CH.sub.2 --CH.sub.2 OR.sup.9, (g) --CH(OR.sup.3)--CH(OR.sup.9)--CH.sub.2 OR.sup.10, and (h) .dbd.N--OR.sup.3 ; and R.sup.1, R.sup.2, R.sup.3, R.sup.9, and R.sup.10 are independently selected from (a) hydrogen, (b) alkyl, and (c) optionally substituted phenyl, are prostaglandin biosynthesis inhibitors and are useful in the treatment of inflammatory disease states. Also disclosed are prostaglandin inhibiting compositions, a method of inhibiting prostaglandin biosynthesis in a mammal.

The prostaglandins are extremely potent substances which produce a wide variety of biological effects, often in the nanomolar to picomolar concentration range. The discovery of two forms of prostaglandin endoperoxide H synthase, PGHS-1 and PGHS-2, that catalyze the oxidation of arachidonic acid leading to prostaglandin biosynthesis has resulted in renewed research to delinate the role of these two isozymes in physiology and pathophysiology. These isozymes have been shown to have different gene regulation and represent distinctly different prostaglandin biosynthesis pathways. The PGHS-1 pathway is expressed constitutively in most cell types. It responds to produce prostaglandins that regulate acute events in vascular homeostasis and also has a role in maintaining normal stomach and renal function. The newly discovery PGHS-2 pathway involves an induction mechanism which has been liked to inflammation, mitogenesis and ovulation phenomena.
Prostaglandin inhibitors provide therapy for pain, fever, and inflammation, and are useful therapies, for example, in the treatment of rheumatoid arthritis and osteoarthritis. The non-steroidal antiinflammatory drugs (NSAIDs) such as ibuprofen, naproxen and the fenamates inhibit both isozymes, prostaglandin endoperoxide H synthase 1 (PGHS-1) and prostaglandin endoperoxide H synthase 2 (PGHS-2). Inhibition of the constitutive enzyme PGHS-1 results in gastrointestinal side effects including ulcers and bleeding and incidence of renal problems with chronic therapy. Inhibitors of the induced isozyme PGHS-2 are proposed to provide antiinflammatory activity without the side effects of PGHS-1 inhibitors. A general review of the current knowledge of PGHS-1 and PGHS-2 isozyme properties and a summary of inhibitors and their activity is provided by:
(1) Battistini, B.; Botting, R.; Bakhle, Y. S. COX-1 and COX-2: toward the development of more selective NSAIDs, Drug New and Perspectives 1994, 7(8), 501-512. PA1 (2) DeWitt, D. L.; Bhattacharyya, D.; Lecomte, M.; Smith, W. L. The differenctial susceptibility of prostaglandin endoperoxide H synthases-1 and -2 to nonsteroidal anti-inflammatory drugs: aspirin derivatives as selective inhibitors. Med. Chem. Res. 1995, 5(5), 325-343. PA1 (3) Mitchell, J. A.; Larkin, S.; Williams, T. J. Cyclooxygenase-2: regulation and relevance in inflammation. Biochem. Pharm. 1995, 50(10), 1535-1542.
Fenamate compounds were developed as prostaglandin biosynthesis inhibitors prior to the discovery of the different isozyme forms. The reported fenamates (Scherrer, R. A. Fenamic acids, in "Anti-inflammatory and anti-rheumatic drugs", Vol II, Rainsford, K. D. ed., CRC Press, Boca Raton, Fla., 1985, Chapter 4, pp 65-85) include: diclofenac, meclofenamic acid, mefenamic acid, flufenamic acid, and tolfenamic acid. Meclofenamic acid, a representative fenamate NSAID, has been reported to inhibit both PGHS-1 and PGHS-2 (Battistini, B.; Botting, R.; Bakhle, Y. S. COX-1 and COX-2: toward the development of more selective NSAIDs, Drug New and Perspectives 1994, 7(8), 501-512.)

Iminoxyderivatives of fenamates as inhibitors of prostaglandin biosynthesis


Disclosed is a semiconductor memory including ferroelectric capacitors. Memory cells each including a ferroelectric capacitor and an insulted-gate-type cell transistor are connected to a corresponding one of bit lines. Insulated-gate-type separating transistors are connected between multiple bit-line selecting transistors and multiple sense amplifiers, respectively. When the separating transistors are turned on, data retained in the sense amplifiers are capable of being written to the memory cells during the same time period substantially.

FeRAM (Ferroelectric Random Access Memory), MRAM (Magnetic Random Access Memory), PRAM (Phase Change Random Access Memory) and RRAM (Resistive Random Access Memory) have been developed as next-generation semiconductor memory devices.
FeRAM is disclosed, for example, in Japanese Patent Application Laid-open Publication No. 2000-339973. This type of FeRAM is composed of multiple memory cells arranged in a matrix, and each of the memory cells includes a ferroelectric capacitor and an insulated-gate-type cell transistor. Data are written to, and read from, the ferroelectric capacitors through corresponding bit and word lines respectively which are connected to the insulated-gate-type cell transistors.
Such a type of semiconductor memory device performs a write operation which will be described with reference to FIG. 4 hereafter.
As shown in FIG. 4, voltages of the respective column selecting lines CSL0, CSL1, . . . , CSLn−1 are sequentially raised from a "Low" level to a "High" level. In response, voltages of the respective bit lines /BL0, BL0, /BL1, BL1, . . . , /BLn−1, BLn−1 are raised or dropped. The raised and dropped voltages of the bit lines continue to be written to the memory cells connected to the bit line as data.
As shown in FIG. 5, a ferroelectric film to be used for a ferroelectric capacitor gradually increases its polarization amount over a polarization inversion time. When the polarization inversion time becomes, for example, equal to or longer than approximately 1000 ns, the polarization amount becomes saturated. This polarization property depends on temperature T° C. For this reason, when the ambient temperature around the ferroelectric capacitor becomes higher, the polarization amount accordingly increases. As a result, the polarization amount is smaller in a memory cell when the write time is shorter for the memory cell, while the polarization amount is larger in a memory cell when the write time is longer for the memory cell.
Such a type of memory cell is usually tested in terms of its data retention capability and imprint capability. During these tests, it is likely that a defect-free memory cell may be judged as a defective one because the polarization amount is insufficient, when the time period to write data to the memory cell is too short. In addition, it is likely that a defective memory cell may be judged as a defect-free one because the polarization amount is sufficient, when the time period to write data to the memory cell is too long.
These facts may make it difficult to test the semiconductor memory device accurately in terms of its data retention capability and imprint capability. As a result, it is likely that semiconductor memories each including less reliable memory cells may be shipped out. If a more rigid screening test is applied to semiconductor memory devices, the yield of the semiconductor memory devices may be reduced.


The present invention provides a photomultiplier tube interface device (PMT), comprising a PMT module and a circuit substrate. The PMT module comprises a plurality of pins formed at a front end. A plurality of contacts are disposed on a lateral side of the circuit substrate to be electrically connected to the plurality of pins while a connecting base is arranged at a peripheral portion on another lateral side of the circuit substrate to be electrically connected to the contacts. By means of the interface device, not only the connecting pins of the PMT can be protected from being damaged and generating high frequency noise but also the convenience for assembling or replacing the PMT can be improved.

1. Field of the Invention
The present invention generally relates to an interface device and, more particularly, to a photomultiplier tube (PMT) interface device.
2. Description of the Prior Art
The positron emission tomography (PET) scan has been developed since Browell's work on the positron scintillation camera in 1953. In 1975, Ter-Pogossian developed positron emission transaxial tomography (PETT), using a scintillation detector comprising scintillation crystals at the front end to convert the γ-ray photons into scintillation signals. On the back end, there is a photomultiplier tube comprising a photocathode to convert the scintillation signals into photoelectrons by the photoelectric effect. The photoelectrons bombard the dynode, which is applied with 200-400 volts, to generate secondary electrons. The secondary electrons multiply after bombarding a plurality of dynodes and will be collected by the anode to cause a pulse signal. The magnitude of the pulse signal is proportional to the number of scintillation photoelectrons received by the photocathode. A weak optical signal can be amplified by a photomultiplier tube and the amplification depends on the voltage applied on the dynode.
In early PET systems, the sodium iodide NaI(Tl) crystal is used. However, the NaI(Tl) crystal is not suitable for use in converting the γ-ray photons into scintillation signals when the photon energy reaches 511 keV, unless the thickness of the NaI(Tl) crystal with lowered imaging resolution. The BGO (bismuth germanate, Bi3Ge4O12) crystal is widely used in modern PET systems because the BGO crystal exhibits higher efficiency. The LSO (lutetium oxyorthosilicate) crystal exhibits higher density, higher stopping power and higher conversion efficiency than the BGO crystal. However, the LSO crystal is not as widely used as the BGO because of its cost and bottleneck issues in manufacture.
Please refer to FIG. 1, which is 3-D schematic diagram of a conventional scintillation crystal detecting module. The conventional scintillation crystal detecting module 1 comprises a scintillation crystal unit 10, a PMT module 11 and a circuit substrate 13. The scintillation crystal unit 10 comprises a plurality of scintillation crystals formed of NaI, LSO or BGO arranged in an array. One end of the PMT module 11 is coupled to the scintillation crystal unit 10 to receive an optical signal from the scintillation crystal unit 10 and then convert the optical signal into an electrical signal. At another end, the PMT module 11 comprises a plurality of pins 12 to be electrically connected to the circuit substrate 13. The circuit substrate 13 is a circuit board. There are contacts 14 on the circuit board to be connected to the pins 12. At the center of the circuit substrate 13, a connecting base 15 is provided. The connecting base 15 is connected to the contacts 14 and provides a terminal 150 for connection with an imaging system (for example, a PET imaging system or a SPECT imaging system).
However, the conventional scintillation crystal detecting module 1 has some problems such as:
1. Since there is no protection between the pins 12 and the circuit substrate 13, the pins 12 are possibly damaged and exposed to cause high-frequency noise. Moreover, it is possible that the user touches the pins 12 to cause hazards.
2. The pins 12 of the PMT module 11 are welded to the circuit substrate 13. Therefore, it is inconvenient to assemble and replace a mal-functional PMT when any PMT in the PMT module 11 is damaged or aged.
3. The circuit substrate 13 can be further connected to another circuit substrate 16 using the connecting base 15 with a pin header. Therefore, the connection between the circuit substrate 13 and the circuit substrate 16 is unfixed and requires additional screws for fixation, which increases the substrate area.
4. In order to prevent the PMT pins 12 from contacting the circuitry on the circuit substrate 13, the PMT pins 12 have to be concave inwards, which results in unfixed connection between the PMT pins 12 and the circuit substrate 13.
Therefore, there is need in providing a PMT interface device and a scintillation crystal detecting module using the PMT interface device to overcome the aforementioned problems.

Institute of Nuclear Energy Research Atomic Energy Council, Executive Yuan


The present invention provide a method for preparing asymmetric separation membrane having thin skin layer having reduced numbers of pin holes on the surface of the membrane for separating water/organic solvent or gas. Imide type asymmetric hollow fiber membrane according to the present invention has superior separation degree and permeability of water/organic solvent or gas over general imide type asymmetric hollow fiber membrane.

Generally, separation membranes are useful and economically efficient for separating materials, and many researches have been devoted to the development of them. In particular, a good many researches have been proceeded to find proper materials for membrane as well as proper processes for membrane separation. Until now, various kinds of membrane materials are developed and still are actively studied. Among imide type-polymer which is useful for support of composite membrane, polyetherimide is an excellent membrane material for water/alcohol separation or gas separation (q.v. "K. V. Peinemann: Journal of Membrane Science 27 (1986) 215-216").
Polyetherimide is developed by General Electric Company in a trademark of "ULTEM", which is noncrystalline thermoplastic and has very high glass transition temperature of 215.degree. C. This polyetherimide is considered as one of very important membrane materials having high mechanical strength and heat stability in addition to good separation degree. The preparation of asymmetric hollow fiber from polyetherimide in order to utilize such good properties in the field of separation membrane is reported (q.v. "K. Kneifel and K. V. Peinemann: Journal of Membrane Science, 65 (1992) 295307).
However, in case of preparing asymmetric hollow fiber using polyetherimide, there occurs a problem that pin holes form in the surface of the asymmetric hollow fiber membrane.
Asymmetric hollow fiber membrane consists of surface skin layer of dense structure and lower support layer having larger pores as shown in FIG. 1. Such an asymmetric hollow fiber membrane are subject to influence resulting from the change of conditions in the process of membrane preparation.
In the prior art, asymmetric hollow fiber membrane can be prepared by wet spinning or dry-wet spinning a solution of desired materials. The main factors having effect on the structure of asymmetric hollow fiber membrane are concentration and composition of polymer solution, solvent type of polymer, coagulating agent, spinning temperature or spinning height. Therefore, one can prepare asymmetric hollow fiber membrane having desired structure if he can control properly those factors in the course of preparing asymmetric hollow fiber membrane (qq.v "J. G. Wijmans, P. B. Baaij and C. A. Smolders: Journal of Membrane Science, 14 (1983) 266-274, D. M. Koenhen and H. M. Mulder and C. A. Smolders: Journal of Applied Polymer Science, 21 (1977) 199").
Asymmetric hollow fiber membrane thus prepared has several advantages: Firstly, asymmetric hollow fiber membrane has higher permeability over plain membrane of single material since it has thin skin layer, as shown in FIG. 1. At the same time, it can possess good mechanical strength without having harmful effect on permeability due to high porous, base support. Secondly, asymmetric hollow fiber can be used as a support for composite membrane since it is porous. Herein, a composite membrane means a membrane made by coating membrane material having good separation property thinly on high porous support. Those membranes have merits in improvement of permeability while possessing good separation property.
In spite of having those advantages, it is very difficult to prepare asymmetric hollow fiber membrane having thin skin layer having reduced numbers of pin holes on the surface of membrane. Because of that difficulty, most hollow fiber membrane presently available in the market are in the form of composite membrane using asymmetric hollow fiber. However, such a composite membrane has mechanical property inferior to single material membrane due to complicated process steps.
Therefore, there exists a need to provide a method for preparing asymmetric separation membrane having thin skin layer having reduced numbers of pin holes on the surface of membrane for separating water/organic solvent or gas.

Method for preparing asymmetrical separation membrane for separating water/organic solvent or gas

Korea Research Institute of Chemical Technology


A power amplifier controller for detecting saturation of the power amplifier (203) and corrects the automatic output control voltage (231) to avoid any further saturation. A detector (211) detects the power of the radio frequency (RF) output signal (211) and generates a signal (229) correlated to the detected power. Comparator (217) compares changes in that signal (229) to changes in the voltage of the AOC signal (231). The comparator (217) generates a signal (233) correlated to saturation of the power amplifier (203) for a DSP (223). The DSP (223) checks the status of this signal (233). Upon detecting saturation, an algorithm contained within the DSP methodically reduces the voltage of the AOC signal (231) until there is a change in the power of the RF output signal (211).

The use of power amplifiers in transmitting radio frequencies (RF) signals has many applications, including but not limited to radiotelephone communications systems. In a radiotelephone communications system, there are multiple fixed site transceivers. Each fixed site transceiver is an interface between the line telephone system and multiple, portable, or mobile radiotelephone systems contained within a geographic area served by the fixed site transceiver. The fixed site transceiver and the radiotelephone communicate by sending and receiving FM modulated radio frequency signals to each other.
In an analog radiotelephone system, there is a large available RF spectrum available for radiotelephone communications. The available RF spectrum is channelized into relatively narrow segments of frequency. Upon request, each radiotelephone is allocated a frequency channel upon which to broadcast and receive information from the fixed site transceiver. This is known as a Frequency Division Multiple Access (FDMA) system. During a phone call, the radiotelephone transmitter would turn-on and remain on the fixed frequency for the entire time of the phone call. Thus, the transmitter and subsequently the power amplifier (PA) of the radiotelephone only needed to turn-on once and turn-off once for a given phone call which could last several minutes. The fixed site transceiver could also remain on for the duration of a phone call. In an FDMA system, since there are a limited number of turn-ons, the turn-on and turn-off requirements of the power amplifier are not very stringent. If a transmitter is turned on quickly, there is a momentary large burst of noise, however, since this would only occur once during a conversation, it would not substantively affect the communication system. Similarly, if the power amplifier is turned on slowly, there would be an imperceptible gap in the conversation at the beginning of a phone call. These problems are only inconveniences to the user and are not substantive system degrading problems.
In the newly proposed digital cellular radiotelephone systems, the power amplifier turn-on requirements have increased dramatically. The new systems use a time division multiple access (TDMA) communications system. In a TDMA communications system, 8 or 16 radiotelephones share a single 200 kilohertz wide channel on which to broadcast. Each radiotelephone in a channel is allocated one 577 microsecond (uS) time slot on a repetitive basis. During this time slot the radiotelephone ramps up the power amplifier to the proper frequency and power, sends the desired data, and ramps down the power amplifier so as not to disturb or interfere with the other users sharing the same frequency. Thus, the requirements for controlling the power amplifier are greatly increased.
The Group Special mobile (GSM) recommendations ETSI/PT-12 05.05 (4.2.2 and 4.5.2), March, 1991 were developed to define a digital radiotelephone communications system. These recommendations were aware of the increased power amplifier requirements and have defined a time mask and a spectral frequency mask, as illustrated in FIGS. 7 and 8, which all radiotelephone equipment used in the system must meet. The specifications concerning the time and frequency masks demand the development of a very smooth ramp up of the PA under stringent time constraints.
Saturation of a power amplifier occurs when the power amplifier cannot produce as much power as the control circuitry demands. Saturation may be caused by decreased availability of battery voltage in a portable radiotelephone or environmental temperature extremes. Saturation of the power amplifier can cause two problems. Namely, the saturated power amplifier may damage some properties of the power amplifier (PA), subsequently reducing the efficiency of the PA's operation. Second, excessive power amplifier control voltage will require an excessive amount of time to shut down the PA.
If the time required to ramp down the PA is excessive, even a few microseconds, then the PA will interfere with other PAs which are utilizing the same frequency. This interference will cause data being transmitted between the fixed site transceivers and the radiotelephones to be lost. This loss will degrade the entire radiotelephone communications system. Therefore, a power amplifier controller is needed which limits the saturation time of the PA especially at the end of the PA's transmitting time.

Power amplifier saturation detection and correction method and apparatus


A method of reducing side-effects associated with administering oxygen-carrying proteins to mammals is disclosed. The method includes:. a) reacting an oxygen-carrying protein with a substantially non-antigenic polymer to form a oxygen-carrying protein-substantially non-antigenic polymer conjugate; and PA1 b) administering the oxygen-carrying protein-substantially non-antigenic polymer conjugate to a mammal in need of the oxygen-carrying protein. Preferred oxygen-carrying proteins include recombinantly prepared hemoglobins and preferred non-antigenic polymers include polyethylene glycol.

1. Field of the Invention
The present invention relates to methods of reducing the side-effects associated with administering oxygen-carrying proteins to mammals. In particular, the present invention relates to methods of reducing the side-effects associated with administering hemoglobin-containing compositions to mammals in need thereof.
2. Description of Related Art
Over the years, several substances have been suggested as potential replacements for the naturally-occurring hemoglobin-based oxygen transport systems of mammals. For example, the scientific literature often includes reports of various blood substitutes such as perfluorocarbon emulsions, recombinant hemoglobin products, cross-linked hemoglobin compositions which include human or bovine hemoglobins, ultra-purified bovine hemoglobin compositions and polyethylene glycol-hemoglobin conjugates.
Not unexpectedly, there have been shortcomings associated with many of the products under consideration. For example, early perfluorocarbon emulsions have not been favorably accepted due to drawbacks associated with product preparation before use (dilution and mixing), detergent based-emulsifying agents and the requirement that the patient breathe 95% oxygen during use. In addition, the compounds have a short circulating life, and are known to accumulate in the liver and spleen. The product is not metabolized per se but rather is exhaled as a gas over time through the lungs. Given the prolonged organ residence time, toxicities including thrombocytopenia have raised concerns regarding multiple doses and tissue loading.
In addition, the (in vivo) circulating life of some blood substitutes has been less than that which is believed to be therapeutically optimal. Some solutions have been offered to address this shortcoming. For example, inter- and/or intra-molecular cross-linking hemoglobin molecules or covalently attaching polymers such as PEG have been suggested as means for extending the circulating life of the oxygen carriers. See also U.S. Pat. Nos. 5,234,903, 5,386,014, 5,312,808 and 5,478,805, the contents of which are each incorporated herein by reference.
Some proposed products have been associated with significant side-effects after intravenous administration. Side-effects, if significant, substantially reduce the commercial and therapeutic value of these products. For example, some recombinant hemoglobin products undergoing clinical evaluation were found to unexpectedly cause alpha-adrenergic, acetylcholine-mediated, possible endothelin and/or nitric oxide-induced side effects in humans after administration. These side-effects are believed to be related to not only the dose of the recombinant hemoglobin administered but also the formulation of the recombinant hemoglobin and volume administered. Current recombinant hemoglobin formulations under consideration, therefore, are of limited usefulness especially in situations where large amounts of the recombinant protein are required for treatment. Large volume administration of such preparations for replacement of blood loss due to trauma or transfusions are likely to result in one or more side-effects.
It would be highly desirable to provide a method of allowing oxygen-carrying proteins to be delivered to patients in relatively large volumes without significantly incurring the types of side-effects which heretofore were observed. The present invention addresses this issue and is described below.

Method of reducing side effects associated with administration of oxygen-carrying proteins


The present invention relates to an improved synthesis of pyrrole capping group precursors.

Infection by hepatitis C virus ("HCV") is a compelling human medical problem. HCV is recognized as the causative agent for most cases of non-A, non-B hepatitis, with an estimated human sero-prevalence of 3% globally [A. Alberti et al., "Natural History of Hepatitis C," J. Hepatology, 31., (Suppl. 1), pp. 17–24 (1999)]. Nearly four million individuals may be infected in the United States alone [M. J. Alter et al., "The Epidemiology of Viral Hepatitis in the United States, Gastroenterol. Clin. North Am., 23, pp. 437–455 (1994); M. J. Alter "Hepatitis C Virus Infection in the United States," J. Hepatology, 31., (Suppl. 1), pp. 88–91 (1999)]. Unfortunately, there are no broadly effective treatments for the debilitating progression of chronic HCV.
There are not currently any satisfactory anti-HCV agents or treatments. Until recently, the only established therapy for HCV disease was interferon treatment. However, interferons have significant side effects [M. A. Wlaker et al., "Hepatitis C Virus: An Overview of Current Approaches and Progress," DDT, 4, pp. 518–29 (1999); D. Moradpour et al., "Current and Evolving Therapies for Hepatitis C," Eur. J. Gastroenterol. Hepatol., 11, pp. 1199–1202 (1999); H. L. A. Janssen et al. "Suicide Associated with Alfa-Interferon Therapy for Chronic Viral Hepatitis," J. Hepatol., 21, pp. 241–243 (1994); P. F. Renault et al., "Side Effects of Alpha Interferon," Seminars in Liver Disease, 9, pp. 273–277. (1989)] and induce long term remission in only a fraction (˜25%) of cases [O. Weiland, "Interferon Therapy in Chronic Hepatitis C Virus Infection", FEMS Microbiol. Rev., 14, pp. 279–288 (1994)]. Recent introductions of the pegylated forms of interferon (PEG-INTRON® and PEGASYS®) and the combination therapy of ribavirin and pegylated interferon (REBETROL®) have resulted in only modest improvements in remission rates and only partial reductions in side effects. Moreover, the prospects for effective anti-HCV vaccines remain uncertain.
The HCV nonstructural (NS) proteins are presumed to provide the essential catalytic machinery for viral replication. The HCV NS3 serine protease and its associated cofactor, NS4A, helps process all of the viral enzymes, and is thus considered essential for viral replication. This processing appears to be analogous to that carried out by the human immunodeficiency virus aspartyl protease, which is also involved in viral enzyme processing HIV protease inhibitors, which inhibit viral protein processing are potent antiviral agents in man, indicating that interrupting this stage of the viral life cycle results in therapeutically active agents. Consequently it is an attractive target for drug discovery.
Protease inhibitors and many other compounds comprise N-terminal capping groups. Such N-terminal capping, or protecting, groups are not limited to HCV protease inhibitors. Any peptidyl biologically active compound may have an N-terminal capping group. Similarly, many non-peptidyl (particularly peptidyl mimetic) compounds comprise the equivalent of an N-terminal capping group. Furthermore, a primary or secondary amine in any compound could be derivatized with a capping group. Accordingly, N-terminal capping groups are widely used. There is therefore a need for N-terminal capping groups (sometimes referred to as protecting or protective groups) and methods for making such groups.
A pyrrole-based capping group that is particularly useful has been described (WO 03/087092). This capping group is relatively complex. A disadvantage of relatively complex capping groups is that they may not be readily available commercially and/or may be difficult to synthesize. As is known, carboxylic acids are convenient precursors for such capping groups. Unfortunately, there are no safe, efficient, and/or large-scale methods for synthesizing the carboxylic acid precursors corresponding to these particularly useful capping groups (see, D. T. Kozhich et al., Zh. Organ. Khimii, 16 pp. 849–855–750 (1980); UDC 547, 745: 312; A. J. Robinson et al., J. Org. Chem. 66, pp. 4148–4152 (2001); H. Falk et al. Monatsh. Chemie, 104, pp. 925–923 (1973)).
Thus, there is a need for efficient synthetic routes to these carboxylic acid precursors of pyrrole-based capping groups.