This U.S. non-provisional application, the entire contents of which are incorporated by reference, which claims priority of Korean Patent Application No. 2003-004487, filed on Jan. 23, 2003; Korean Patent Application No. 2003-005211, filed on Jan. 27, 2003; and Korean Patent Application No. 2003-016139, filed on Mar. 14, 2003; all of which were filed in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a recording medium such as BD-ROM (Blu-ray Disc ROM) which has data written in intermittent or alternate wobbled (or zigzag) pits and an apparatus and methods for forming, recording, and reproducing the recording medium.
2. Description of the Related Art
Recently, the standardization of Blu-ray Disc Rewritable (BD-RE), which is a new high-density rewritable optical disk capable of recording large capacity, high-quality video and audio data, is in progress. BD-RE related products are expected to be available on the market in the near future.
As illustrated in
The lead-in area may comprise several pre-assigned areas such as a first guard (Guard 1) area, a permanent information & control data (PIC) area, a second guard (Guard 2) area, a second information (Info 2) area, and an optimum power calibration (OPC) area. The Guard 1 area and the PIC area are pre-recorded areas in which some initial data is pre-recorded, whereas the other areas of the lead-in area, the data area, and the lead-out areas are all rewritable areas.
In the PIC area, important permanent disc information is encoded in a wobbled groove by high frequency modulation (HFM).
HFM Grooves may be modulated in the radial direction with a rather high bandwidth signal, to create a data channel for replicated information with sufficient capacity and data rate.
As depicted in
Also, a read-only Blu-ray Disk (BD-ROM) is also under development along with the BD-RE. A BD-ROM may include an inner area, a clamping area, a transition area, an information area, and a rim area, as shown in
The information area may further comprise a BCA, a lead-in zone, a data zone, a lead-out zone, and an outer zone. As in BD-RE, the BCA may contain disc important information (DII), such as a disc serial number and copy protection information (CPI). If a BD-ROM is copy protected, the DII may be required to decrypt the main data contained on the BD-ROM.
The disc information in the PIC zone may be recorded as straight pits in the same way as main data such as audio/video (A/V) streams are recorded in the data zone. The disc information may be 17PP-modulated data written in the form of an error correction code (ECC) block of size 64 KB, for example.
In this case, however, it takes some demodulation time to retrieve the disc information from the BD-ROM because the disc information may be demodulated by an RF signal detection method.
As described above, the disc information contained in the PIC area of a BD-RE may be encoded in a wobbled groove by HFM. If the disc information is recorded in the PIC zone of a BD-ROM as straight pits, an optical disk reproducing apparatus should be able to apply different detecting schemes to obtain the disc information depending on the disk type (BD-RE or BD-ROM). Unless the correct scheme is chosen, the optical disk reproducing apparatus will fail to detect the disc information. For example, if a method for detecting HFM-modulated disc information encoded in a wobbled groove of a BD-RE is applied to a BD-ROM, the optical disk reproducing apparatus will not be able to retrieve the disc information which is recorded in the PIC zone as straight pits.
In addition, if the disc important information (DII) contained in the BCA cannot be retrieved due to a read error, it is impossible to retrieve the data recorded on the disk. For example, if an error occurs while the copy protection information (CPI) is retrieved from the BCA, it may be impossible to reproduce the main data recorded in the data zone because the data cannot be decrypted.
Also, because the copy protection information (CPI) recorded on PIC area of the disk includes important data, e.g., key data to decrypt an encrypted main data recorded on the data zone, it should not be detected easily by any illegal device and copied to other recording media to protect the encrypted contents recorded on the disk. It should be only detected by a desired detection method in a legally permitted device to ensure robustness.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, capable of rapidly detecting disc information required for reproducing the contents recorded thereon, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, capable of reproducing main data even if there is a failure in reading disc important information from one or more location on the recording medium, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, including decryption information for decrypting contents recorded on the recording medium in such a way that the decryption information is not copied to other recording media and/or other types of recording media, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, which contains disc information encoded in wobbled pits in some sections of the recording medium, such as the PIC zone, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, which contains disc important information in more than one location, for example, in the BCA and in another area other than the BCA, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, which contains copy protection information encoded in wobbled pits, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, which contains copy protection information encoded in intermittently formed arrays of wobbled pits in a distributed manner, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, which contains pits formed along tracks, with data recorded therein, the data including copy protection information for encryption and/or decryption, wherein pits formed in some portions of the tracks are shifted from a track center to left and/or right to thereby form intermittent or alternate wobbled pits, wherein key information for encryption and/or decryption is encoded in a deviation shape of said pits shifted from the track center, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.
In exemplary embodiments, the present invention is directed to method for forming a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, including forming pits formed along tracks, with data recorded therein, the data including copy protection information for encryption and/or decryption, wherein pits formed in some portions of the tracks are shifted from a track center to left and/or right to thereby form intermittent or alternate wobbled pits, wherein key information for encryption and/or decryption is encoded in a deviation shape of said pits shifted from the track center.
In exemplary embodiments, the present invention is directed to method for reproducing a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, including utilizing data recorded in pits formed along tracks, the data including copy protection information for encryption and/or decryption, wherein pits formed in some portions of the tracks are shifted from a track center to left and/or right to thereby form intermittent or alternate wobbled pits, wherein key information for encryption and/or decryption is encoded in a deviation shape of said pits shifted from the track center.
In exemplary embodiments, the present invention is directed to method for recording a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, including recording data in pits formed along tracks, the data including copy protection information for encryption and/or decryption, wherein pits formed in some portions of the tracks are shifted from a track center to left and/or right to thereby form intermittent or alternate wobbled pits, wherein key information for encryption and/or decryption is encoded in a deviation shape of said pits shifted from the track center.
In exemplary embodiments, the present invention is directed to method for recording a recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, including utilizing pits formed along tracks, with data recorded therein, the data including copy protection information for encryption and/or decryption, wherein pits formed in some portions of the tracks are shifted from a track center to left and/or right to thereby form intermittent or alternate wobbled pits, wherein key information for encryption and/or decryption is encoded in a deviation shape of said pits shifted from the track center.
In exemplary embodiments, the present invention is directed to a recording medium, including indicating information indicating whether or not the recording medium contains copy protection information for use in generating or processing copy protected user data, wherein the indicating information and/or the copy protection information are formed as a wobbled pattern and copied to a specific area.
In exemplary embodiments, the present invention is directed to a method of recording data on a recoding medium including utilizing indicating information indicating whether or not the recording medium contains copy protection information for use in generating or processing copy protected user data, wherein the indicating information and/or copy protection information are formed as a wobbled pattern and copied to a specific area and recording the data based on the copy protection information.
In exemplary embodiments, the present invention is directed to a recording medium including first information for use in generating or processing copy protected user data and second information for use in generating or processing copy protected first information, wherein the first information and/or the second information are formed as a wobbled pattern and copied to a specific area.
In exemplary embodiments, the present invention is directed to a method of recording data on a recording medium including utilizing first information for use in generating or processing copy protected user data and second information for use in generating or processing copy protected first information, wherein the first information and/or second information are formed as a wobbled pattern and copied to a specific area and recording the copy protected user data in the recording medium.
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate exemplary embodiments of the invention, and together with the description, serve to explain the principles of the present invention.
In the drawings:
In order that the invention may be fully understood, exemplary embodiments thereof will now be described with reference to the accompanying drawings.
The BD-ROM in accordance with exemplary embodiments of the invention may include an inner area, a clamping area, a transition area, an information area, and a rim area, as described above with reference to
The copy protection information may not be recorded in the BCA and be only recorded in the PIC zone, which is illustrated in
As depicted in
In an exemplary embodiment, the PIC zone may contain 2,720 clusters of data. The first cluster may contain disc information recorded as wobbled pits by bi-phase modulation. The other clusters may contain 17PP modulated disc information and copy protection information having ECC blocks of size 64 KB and recorded as straight pits, for exemple the disc information recorded as wobbled pits may be detected by a push-pull signal detecting method and the disc information and copy protection information recorded as straight pits may be detected by an RF signal detecting method. The push-pull signal typically has lower frequency components than the RF signal.
In an exemplary embodiment, the DII additionally copied to the PIC zone can be encoded in wobbled pits to prevent it from being detected by the RF signal detecting method.
The copy protection information, in one example, the ROM mark, may be encoded in intermittently formed wobbled pits to prevent it from being easily detected by common detecting methods, while the data recorded on the data zone is formed of straight pit.
As shown in
In
All of the arrays of straight pits can be made to have the same length and all of the arrays of wobbled pits can be made to have the same length. If the arrays of pits are of different length, that is, if An≠Am (n≠m) and Bn≠Bm (n≠m), the occurrence of the arrays of wobbled pits is not periodic. This can enhance the security of the copy protection information in that the probability that special information is encoded in wobbled pits becomes lower.
There are various other modulation methods that can be employed to encode the copy protection information in wobbled pits. Analog modulation methods include amplitude modulation (AM), frequency modulation (FM) and digital modulation methods include pulse code modulation (PCM), minimum shift keying (MSK), and binary phase shift keying (BPSK).
Although the same modulation tehcnique can be applied to all arrays of wobbled pits, arrays of wobbled pits can be encoded by different modulation techinques to enhance the security of the copy protection information. In
To decrease possible data read errors, in an exemplary embodiment the same data be repeatedly encoded in arrays of wobbled pits.
A region of wobble pit and a region of no wobble pit may be combined or a plurality of regions may be combined and then a bit for copy protection can be detected. For example, a recording region of wobble pit corresponding to the data bit may be recorded dispersly to several regions, and the wobble pits is formed such that the amplitude of wobble are small, and then the bit can be detected by detecting a pushpull signal of low level and integrating the signal.
In an exemplary embodiment, the copy protection information has a size of no more than 128 bits, but if header information and redundant data for ECC are appended, the size can increase up to 1 KB.
As shown in
Hence, the copy protection information of size 1 KB can be contained in 64 clusters. If an exemplary PIC zone may include 2,720 clusters, the PIC zone will have enough space to store the copy protection information at least one. Further, the copy protection information can be recorded in the PIC zone more than once to enhance reliability of the recorded data.
In other exemplary embodiments, it is also possible to form data frames other than the first data frame of each address unit as wobbled pits or more than two data frames of each address unit as wobbled pits to encode the copy protection information.
Instead of encoding the copy protection information in a fixed data frame within each address unit, the information can also be encoded in an arbitrary data frame within each address unit. In this exemplary embodiment, the occurrence of low-frequency signals created by the wobbled pits is not of periodic nature and thus it can enhance the information security as described above.
The copy protection information can also be recorded as straight pits. In this exemplary embodiment, the copy protection information can be encrypted before being recorded and a key value to decrypt the encrypted copy protection information can be encoded in wobbled pits, thereby preventing illegal copying of the contents.
As shown in
That is, the wobbled pit data can be reproduced or detected only when the bi-phased modulation data modelated by HFM is detected or reproduced normally. And also, reproduction or decryption of main data is possible only when the wobbled pit data for copy protection is reproduced or detected using the normally detected or reproduced bi-phase modulation data.
In meantime, if the information is encoded in pits, the occurrence of successive pits of the same length may not be allowed and thus pits of different length appear one after another. In this exemplary embodiment, the positions of data pits may also be shifted at intervals of 18 T to encode data in wobbled pits.
The laser beam reflected by the wobbled pits is converted into electric signals by photo detectors 13-16.
The electric signals may be amplified by a push-pull detecting circuit, wherein Ea+Eb and Ec+Ed are amplified separately by amplifiers 10 and 11 and then the difference signal ((Ea+Eb)−(Ec+Ed)) between the two amplified signals is generated by a differential amplifier 12. The data encoded in the wobbled pits is obtained by comparing the difference signal 501 with a threshold level.
Similarly, the DII and/or disc information (or other information) encoded in wobbled pits can be obtained by a push-pull circuit that is used to create the tracking error signal, with no additional error correction and demodulation processes.
If an error due to scratches or other disc deformities occurs when accessing the BCA of a BD-ROM, the DII can be retrieved from the PIC zone and data recorded on the disk can be reproduced using the retrieved information. As a result, the main data recorded in the data zone may be decrypted using a decryption key contained in the DII recorded in the PIC zone.
Since the data encoded in wobbled pits, for example, DII and/or disc information, is not obtained by demodulation, it is not copied when the contents of the BD-ROM is copied to another rewritable medium and therefore the encrypted data copied to the rewritable medium cannot be decrypted, thereby preventing illegal copying of the BD-ROM contents.
The disc information and copy protection information encoded in straight pits as shown in
The laser beam reflected by the straight pits is converted into electric signals by photo detectors 13-16 and the electric signals (Ea, Eb, Ec, and Ed) are added together with amplification by one or more summing amplifiers 20, 21, and 22. The RF signal, Ea+Eb+Ec+Ed, which is the output of the summing amplifier 22, is converted into a binary pulse train by an RF unit 23 and converted into digital data by a clock signal synchronized with the binary signal. The original disc information and copy protection information are obtained from the digital data by an ECC & demodulator 24.
The disc information and copy protection information encoded in straight pits can be read in the same way that the main data recorded in the data zone is read.
The disc information may include a disc information ID, a disc information format, a disc type ID, disc size/version, etc, as shown in
For example, if the 2-bit data is 00b, the corresponding optical disk is a BD-RE. If the data is 01b, the corresponding optical disk is a one-time recordable BD-R. If the data is 10b, the corresponding optical disk is a BD-ROM.
The disc information size and a flag indicating whether it is the last disc information can be assigned to a reserved field of the disc information.
The VDP system 31 can detect the disc information encoded in wobbled pits, e.g., a key data to encrypt and/or decrypt the main data of data zone, in the PIC zone from the push-pull signal.
Where the disc information size and a flag indicating whether it is the last disc information are assigned to a reserved field, the disc information and copy protection information recorded in the PIC zone can be detected more accurately using the information in the reserved field.
In another exemplary embodiment, it is possible that a transition zone for separately detecting the disc information and the copy protection information is allocated to the PIC zone.
If the copy protection information is encrypted and encoded in straight pits, the VDP system 31 detects the decryption key encoded in wobbled pits in the PIC zone as described in
The high-density, read-only, and/or optical disk and disc information recording method therefore in accordance with exemplary embodiments of the invention may repeatedly record important information required for the protection of the contents recorded on the disk and encode the information in wobbled pits, thereby enhancing data reliability and preventing illegal copying of the contents of the disk.
Although exemplary embodiments of the present invention have been described in conjunction with a high-density, read-only recording medium, the teachings of the present invention are also applicable to other recording media, such as recordable, rewritable, or rewritable once media and methods and apparatuses associated therewith, as would be known to one of ordinary skill in the art.
Although certain exemplary embodiments of the present invention have been disclosed, it is noted that the present invention may be embodied in other forms without departing from the spirit or essential characteristics thereof. The exemplary embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Number | Date | Country | Kind |
---|---|---|---|
10-2003-0004487 | Jan 2003 | KR | national |
10-2003-0005211 | Jan 2003 | KR | national |
10-2003-0016139 | Mar 2003 | KR | national |
Number | Name | Date | Kind |
---|---|---|---|
4879707 | Getreuer et al. | Nov 1989 | A |
5295127 | Verboom et al. | Mar 1994 | A |
5572507 | Ozaki et al. | Nov 1996 | A |
5596639 | Kikinis | Jan 1997 | A |
5689486 | Shimizu et al. | Nov 1997 | A |
5706268 | Horimai | Jan 1998 | A |
5737286 | Timmermans et al. | Apr 1998 | A |
5799501 | Leonard et al. | Sep 1998 | A |
5802174 | Sako et al. | Sep 1998 | A |
5809006 | Davis et al. | Sep 1998 | A |
5818805 | Kobayashi et al. | Oct 1998 | A |
5848050 | Nagasawa et al. | Dec 1998 | A |
5878007 | Matsumoto et al. | Mar 1999 | A |
5892797 | Deng | Apr 1999 | A |
5894463 | Okawa et al. | Apr 1999 | A |
6021199 | Ishibashi | Feb 2000 | A |
6031815 | Heemskerk | Feb 2000 | A |
6072758 | Tajiri | Jun 2000 | A |
6150888 | Nakazawa | Nov 2000 | A |
6215759 | Tanoue et al. | Apr 2001 | B1 |
6223247 | Otsuka et al. | Apr 2001 | B1 |
6223285 | Komuro et al. | Apr 2001 | B1 |
6289102 | Ueda et al. | Sep 2001 | B1 |
6353890 | Newman | Mar 2002 | B1 |
6516064 | Osawa et al. | Feb 2003 | B1 |
6519213 | Song et al. | Feb 2003 | B1 |
6538982 | Van Vlerken et al. | Mar 2003 | B1 |
6549495 | Spruit et al. | Apr 2003 | B1 |
6550009 | Uranaka et al. | Apr 2003 | B1 |
6664526 | Yokoi | Dec 2003 | B2 |
6694023 | Kim | Feb 2004 | B1 |
6708299 | Xie | Mar 2004 | B1 |
6738342 | Furumiya et al. | May 2004 | B2 |
6847604 | Ueki | Jan 2005 | B2 |
6885629 | Oshima et al. | Apr 2005 | B2 |
6930977 | Kondo et al. | Aug 2005 | B1 |
6938162 | Nagai et al. | Aug 2005 | B1 |
7006416 | Ohgake | Feb 2006 | B1 |
7142494 | Sako et al. | Nov 2006 | B2 |
7248558 | Kobayashi et al. | Jul 2007 | B2 |
7266074 | Kim et al. | Sep 2007 | B2 |
20010010666 | Miyamoto et al. | Aug 2001 | A1 |
20010036132 | Kobayashi et al. | Nov 2001 | A1 |
20010046193 | Akiyama et al. | Nov 2001 | A1 |
20020024914 | Kobayashi | Feb 2002 | A1 |
20020031079 | Kato | Mar 2002 | A1 |
20020041686 | Moriyama et al. | Apr 2002 | A1 |
20020048241 | Kumagai et al. | Apr 2002 | A1 |
20020048246 | Yamaguchi et al. | Apr 2002 | A1 |
20020076047 | Ando et al. | Jun 2002 | A1 |
20020080960 | Kanayama et al. | Jun 2002 | A1 |
20020089920 | Gotoh et al. | Jul 2002 | A1 |
20020097871 | Gotoh et al. | Jul 2002 | A1 |
20020144114 | Barnard et al. | Oct 2002 | A1 |
20020181358 | Sako | Dec 2002 | A1 |
20030007432 | Minamino et al. | Jan 2003 | A1 |
20030012375 | Sako et al. | Jan 2003 | A1 |
20030048725 | Lee et al. | Mar 2003 | A1 |
20030053404 | Kondo | Mar 2003 | A1 |
20030117920 | Sako et al. | Jun 2003 | A1 |
20030174605 | Sako et al. | Sep 2003 | A1 |
20030185128 | Shoji et al. | Oct 2003 | A1 |
20040076110 | Hino et al. | Apr 2004 | A1 |
20040120247 | Lee et al. | Jun 2004 | A1 |
20040151091 | Ma et al. | Aug 2004 | A1 |
20050018555 | Sabi et al. | Jan 2005 | A1 |
20050099916 | Jeon et al. | May 2005 | A1 |
20050122889 | Kobayashi et al. | Jun 2005 | A1 |
Number | Date | Country |
---|---|---|
1152170 | Jun 1997 | CN |
1293810 | May 2001 | CN |
1362707 | Aug 2002 | CN |
0 299 573 | Jan 1989 | EP |
0 545 472 | Jun 1993 | EP |
0 723 216 | Jul 1996 | EP |
0 756 279 | Jan 1997 | EP |
0 807 929 | Nov 1997 | EP |
0 898 271 | Feb 1999 | EP |
0 936 610 | Aug 1999 | EP |
0 997 899 | May 2000 | EP |
1028423 | Aug 2000 | EP |
1 058 254 | Dec 2000 | EP |
1067540 | Jan 2001 | EP |
1 122 729 | Aug 2001 | EP |
1 152 412 | Nov 2001 | EP |
1 168 312 | Jan 2002 | EP |
1 168 328 | Jan 2002 | EP |
1 229 537 | Aug 2002 | EP |
05-036194 | Feb 1993 | JP |
05-325193 | Dec 1993 | JP |
07-272282 | Oct 1995 | JP |
08-124171 | May 1996 | JP |
08-147704 | Jun 1996 | JP |
09-081938 | Mar 1997 | JP |
09-128874 | May 1997 | JP |
10-003746 | Jan 1998 | JP |
10-172149 | Jun 1998 | JP |
10-269577 | Oct 1998 | JP |
11-066739 | Mar 1999 | JP |
11-86436 | Mar 1999 | JP |
11-261950 | Sep 1999 | JP |
11-317002 | Nov 1999 | JP |
2000-149415 | May 2000 | JP |
2000-195049 | Jul 2000 | JP |
2000-195094 | Jul 2000 | JP |
2000-231722 | Aug 2000 | JP |
2000-298941 | Oct 2000 | JP |
2001-135021 | May 2001 | JP |
2001-167517 | Jun 2001 | JP |
2001-189051 | Jul 2001 | JP |
2001-243355 | Sep 2001 | JP |
2001-256678 | Sep 2001 | JP |
2001-332031 | Nov 2001 | JP |
2001-344765 | Dec 2001 | JP |
2002-042347 | Feb 2002 | JP |
2002-163857 | Jun 2002 | JP |
2002-190159 | Jul 2002 | JP |
2002-197674 | Jul 2002 | JP |
2002-197789 | Jul 2002 | JP |
2002-203369 | Jul 2002 | JP |
2002-203374 | Jul 2002 | JP |
2002-216360 | Aug 2002 | JP |
2002-304809 | Oct 2002 | JP |
2002-311976 | Oct 2002 | JP |
2002-319245 | Oct 2002 | JP |
2002-367281 | Dec 2002 | JP |
2003-006997 | Jan 2003 | JP |
2001-0051834 | Jun 2001 | KR |
10-2004-0048476 | Jun 2004 | KR |
357346 | May 1999 | TW |
408290 | Oct 2000 | TW |
449737 | Aug 2001 | TW |
501131 | Sep 2002 | TW |
512316 | Dec 2002 | TW |
512328 | Dec 2002 | TW |
514895 | Dec 2002 | TW |
WO 9745836 | Dec 1997 | WO |
WO 0021085 | Apr 2000 | WO |
WO 0103136 | Jan 2001 | WO |
WO 03003358 | Jan 2001 | WO |
WO 0152250 | Jul 2001 | WO |
WO 0215183 | Feb 2002 | WO |
WO 0231821 | Apr 2002 | WO |
WO 0237493 | May 2002 | WO |
WO 2004066286 | Aug 2004 | WO |
WO 2004095439 | Nov 2004 | WO |
Number | Date | Country | |
---|---|---|---|
20040168074 A1 | Aug 2004 | US |