AU2244299A - Optical disk and optical disk drive device - Google Patents

Description

S F Ref: 336557DI

IAUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Sony Corporation 7-35, Kitashinagawa 6-chome Shi nagawa-ku Tokyo 141

JAPAN

Mnoru Tobita, Goro Fujita, Yamagami Satoshi Otsuka and Tamotsu Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Optical Disk and Optical Disk Drive Device The following statement is a full description of this invention, Including the best method of performing it known to oieIus:- 9' Cy~ -1- Optical Disk and Optical Disk Drive Device Technical Field This invention relates to an optical disc of the sample servo system and a driving device therefor.

S 5 Background Art There has hitherto been known an optical disc system for recording/ reproducing various data by scanning a concentrically or spirally extending track on a disc by using a laser beam, in which the optical disc is driven at a constant linear velocity (CLV) or at a constant angular velocity (CAV) for recording/reproducing the data. There has also been known an optical disc system of a continuous servo system in which tracking control is performed using a continuous pre-groove formed along the track, or of a sample servo system in which tracking control is performed using discrete servo areas formed on the track. Among the known types of optical discs, there are recordable RAM discs, such as a replay-only ROM disc, a write-once disc or a magneto-optical disc (MO disc), and a so-called partial ROM disc having. both ROM and RAM areas.

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I -2- An optical disc system for use with such optical disc is configured for reading the parameter information for the medium recorded on a phase encoded part (PEP) provided on an inner rim of the optical disc, as prescribed in ISO MO 5.25 inch standards. The system is also configured to read the control information from the control track based upon the control information for carrying out the control operation responsive to the control information.

With the continuous composite servo system (CCS system) standardized in ISO, servo data is affected by data per se. That is, if data recording density is increased, system clocks are reproduced with increasing difficulties, such that it io becomes difficult to achieve high recording density. Furthermore, since the groove and pits must be cut simultaneously, it is also relatively difficult to produce a ROM disc or a partial ROM disc.

~-fli -3- In addition, with the conventional optical disc, a dedicated decoding circuit has been required for reading out the parameter information recorded on the PEP. Since the PEP lacks address information, the pickup position cannot be identified. Since the PEP and the recording area for data per se are in different formats, the two areas are s demarcated from each other by a gap.

B It is another object of the present invention to overcome, or at least ameliorate, one or more of the disadvantages of the prior art.

Disclosure of the Invention Accordingly, in a first aspect, the invention provides an optical disc including to a plurality of substantially concentric tracks, each track defining a plurality of '4 n:'JibelO1 622.do": SEC 1 ik' -4- 4 I segments, wherein each segment has a data area and a servo area, the servo area including: servo pits containing servo information to be read by a corresponding optical disc drive; and a discrimination mark which, by means of its position within the servo area, identifies the segment in which the corresponding servo area is disposed.

In a second aspect, the invention provides an optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to he read by a corresponding optical disc drive: and a data area; wherein at least some of the segments are data segments for recording user d at l a. and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, the data area of each 4 S*i address segment including address information recorded in gray code representation .using a region of five clocks of a clock signal generated by a disc drive based upon the servo pits, for 2-bit information.

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w e i In a third aspect, the invention provides an optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and a data area; wherein at least some of the segments are data segments for recording user data, and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, the data area of each address segment including address information recorded as pits representing a 4-bit gray code representation in an 1l-clock area based on a clock signal generated by a disc drive based upon the servo pits, each address segment having: Se S at C *o CO *3 n i l I nrUibe\O1 622.doc:SEC -6a first area corresponding to 5 clocks for representing an upper two bits of the 4-bit gray code representation; a second area corresponding to 5 clocks for representing a lower two bits of the 4-bit gray code representation; a third area disposed between the first and second areas and corresponding to 1 clock, the third area including a pit when: pits representing the respective upper and lower two bits of the 4-bit gray code representation are at a minimum distance from the third area; or one of the pits representing the respective upper or lower two bits of the 4-bit to gray code representation are at the shortest distance from the third area at the minimum distance from the third area and the other of the respective upper or lower two bits of the 4-bit gray code representation are at a maximum distance from the third area.

In a fourth aspect, the invention provides an optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each 15 segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive: and a data area: l..2 n:Ib\O01622.docSEC -7wherein the optical disc is divided into a plurality of zones, each of which has a uniform number of sectors and a plurality of successive tracks, wherein a number of servo clocks SCKseg per segment and a number of data clocks DCKseg per segment are determined by the relationship: DCKseg SCKseg MIN, where M and N are integers.

In a fifth aspect, the invention provides an optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each H segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and a data area; wherein at least some of the segments are data segments for recording user data, and at least some of the remaining segments are address segments aligned radially :i .on the optical disc with other radially adjacent address segments, the data area of each :i 15 address segment including address information recorded in gray code representation, and wherein media information, coded in the same gray code representation as the address information, is recorded in a media information area within the data areas associated with at least some of the tracks.

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I 'T Itll n:iie062.o:EC8- 11- In a sixth aspect, the invention provides an optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to be read by a s corresponding optical disc drive, and a data area; wherein at least some of the segments are data segments for recording user data, and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, further including a to media information area formed in a plurality of tracks adjacent the inner or outer edges of the optical disc, the media information area containing media information stored in a gray code representation.

In a seventh aspect, the invention provides an optical disc driving device for driving an optical disc, the optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, wherein each segment has a data S area and a servo area, the servo area including: servo pits containing servo information to be read by the disc driving device; and a discrimination mark which, by means of its position within the servo area, S" o20 identifies the segment in which the corresponding servo area is disposed wherein the optical disc driving device includes: -4 reproducing means for reproducing information stored on the optical disc; detection means for detecting the position of said discrimination mark from a signal produced by said reproducing means from the discrimination mark by a differential detection method; and Sdiscrimination means for discriminating the segment based upon the results of detection by said detection means.

In a eighth aspect, the invention provides an optical disc driving device for driving an optical disc, the optical disc including a plurality of substantially concentric trackseach track defining a plurality of segments, wherein each segment has: a data to area; a servo area including servo pits containing servo information to be read by the disc driving device; and a single polarity pre-write area disposed at an end of the data area; the optical disc driving device including: recordingireproducing means for reproducing data from the optical disc and for recording data to the optical disc: i" driving power applying means for applying a low-level reproducing driving power or a high-level recording driving power to said recording/reproducing means: data supplying means for supplying recording data to said recording/reproducing means: and control means for selectively controlling:

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1-'ll FySda-S~E S10 -losaid driving power applying means when an optical pickup of the recording means is moved from said servo area to said pre-write area of said data area, such that the driving power is switched from the reproducing driving power to the recording driving power; said data supply means for supplying data to the optical pickup when the optical pickup is moved from said servo area to said pre-write area of said data area, the data being of the same polarity as the polarity of the pre-write area; and said data supply means for supplying desired data to said optical pickup when said pickup traverses said pre-write area during recording.

1o Brief Description of the Drawings Fig. 1 illustrates a segment structure of an optical disc according to the present invention.

Figs. 2A to 2E illustrate a format of mainly a servo area when the optical disc is a MO disc. Fig. 2A shows clocks in a servo area and a data area, Fig. 2B shows a is servo area having a segment mark SDG, Fig. 2C shows a servo area having an address mark ADM, Fig. 2D shows a servo area having a first sector mark STMI and Fig. 2E shows a servo area having a second sector mark STM2.

SFia. 3 shows a detection system for detecting a first pit in m r-FQ

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11 the servo area in the above optical disc.

Fig.4 shows a format of an address segment in the above optical disc.

shows a portion of an access code recorded in the address segment shown in Fig.4.

Fig.6 shows a format of a data segment in the optical disc.

Fig.7 shows a format of mainly a servo area in a ROM disc.

Fig.8 shows the constitution of an I-frame and an I-data sector of the optical disc.

Fig.9 shows the data format of a data sector of the optical disc.

shows playback signals which is based on a reference pattern of the data sector of the optical disc.

Fig.11 shows a setting parameter of area division in the optical disc.

Fig.12 shows the state of area division in the optical disc.

Fig.13 shows a data format in the optical disc.

Fig.14 shows the arraying state of a GCP segment in the optical disc.

shows the construction of the GCP segment.

Fig.16 shows the relation between the page number of the GCP segment and the frame address of the address segment.

Fig.17 shows the contents of the GCP information of a page number 1 of the GCP segment.

Fig.18 shows the contents of the GCP information of a page

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fi p number 2 of the GCP segment.

Fig.19 shows the contents number 3 of the GCP segment.

shows the contents number 4 of the GCP segment.

Fig.21 shows the contents number 5 of the GCP segment.

Fig.22 shows the contents number 6 of the GCP segment.

Fig.23 shows the contents number 7 of the GCP segment.

Fig.24 shows the contents number 8 of the GCP segment.

Fig.25 shows the contents number 9 of the GCP segment.

Fig.26 shows the contents .1- :i i ~-~sar

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i c of the GCP information of a page of the GCP information of a page of the GCP information of a page of the GCP information of a page of the GCP information of a page of the GCP information of a page of the GCP information of a page of the GCP information of a page rr r r i: a s r 4 :ir? number 10 of the GCP segment.

Fig.27 is a block diagram showing the constitution of an optical disc driving device according to the present invention.

Fig.28 illustrates the focusing capturing in the optical disc driving device.

Fig.29 is a timing chart showing the sampling timing for taking out the clock information from the playback signal waveform of wobbling pits in the optical disc driving device.

is a block diagram showing the constitution of a

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i :4 i ~tr;: ~i ~iF~; -13scrambling circuit provided in a recording/reproducing circuit in the optical disc driving device.

Fig. 31 shows a scramble table of the scrambling circuit.

Best Mode for Carrying out the Invention Referring to the drawings, preferred embodiments of the present invention will be explained in detail.

First, the format of the optical disc according to the present invention is explained. The optical disc of the present invention is a zone CAV-sample servo system optical disc. Meanwhile, the present invention is explained with reference to a replay-only ROM disc and a recordable MO disc. Unless specifically defined, the following description is directed to common contents of the two discs.

The optical disc according to the present invention is divided angularly into 1,400 segments (segment 0 to segment 1399) as shown in Fig. 1. These segments are classified into address segments ASEG and data segments DSEG.

15 In each track of the address segment ASEG, the position information along the .radius of the disc, that is track numbers, and the position in the tangential direction of the track, that is the segment numbers, are pre-recorded by pits. During fabrication of the optical disc, pits are formed based upon this position informatioe. The address I' segments ASEG are present every 14 segments, such that there are 100 address 20 segments in each track. An area from a given address segment ASEG to the next address segment ASEG is one frame, such that there are 100 frames in one track, as shown in Fig. 8. The 13 segments between two neighboring address segments ASEG S are data segments DEG. There are 1300 data segments DSEG in each track. Each i segment is comprised of an area corresponding to 216 servo clocks, namely 24 servo clocks defining a servo area ARs and 192 servo clocks defining a data area ARd. With the address segment ASEG, the data area ARd is constituted by an address area ARda and a laser control area ARdb.

n:\libhe\0 622.doc:SEC z 's tj 6: .L1 i -14- Referring to Figs. 2A to 2D, the format of a MO disc is explained. In the servo area ARs, three pits Pa, Pub and Pc, each 2 servo clocks long, are pre-recorded with a center-to-center spacing from each other corresponding to five servo clocks, as shown in Figs. 2A to 2E. There is also provided a focusing sample area ARfs having a length corresponding to six clocks in the servo area ARs.

By setting the bits Pa, Pub and Pc of the servo area ARs so as to be two servo clocks long, the portions free of pits, namely mirror portions, are diminished, thus rendering it difficult to generate ghost bits during disc molding. Since RF signals can be stably reproduced from the pits Pa, Pub and Pc during accessing, various servo signals, such as tracking servo signals, can be stably produced based upon RF signals reproduced from the pits Pa, Pub and Pc. In addition, by separating the center-tocenter distance between the pits Pa, Pub and Pc by more than a r r r ct r

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pre-set distance, data interference between RF signals reproduced from the pits Pa, Pb and Pc may be reduced significantly. For reducing the data interference between pits, it is desirable to separate the pits Pa, Pb and Pc by not less than five servo clocks.

The second pits Pb disposed between the 11th and 12th clocks and the third pits Pc disposed between the 16th and 17th clocks are wobbling pits, offset from the track centers by ±1/4 track along the disc radius, and give the tracking error information by the difference in amplitude values of RF signals reproduced by these pits Pb and Pc. Also, as explained subsequently by referring to Fig.29, the difference in amplitude values at both shoulder portions of RF signals reproduced from these pits Pb and Pc gives the phase information of servo clocks, while the sum of the phase information gives the clock phase information which is independent on the tracking state.

The first pits Pa at the leading end of the servo area ARs are classified by their positions into an address mark ADM indicating that the segment is an address segment ASEG, a first sector mark STM1 indicating that the segment is a leading segment of the sector, a second sector mark STM2 indicating that the next segment is a segment at the leading end of the sector and a segment mark SGM not belonging to any of the above sector marks.

The first pit Pa becomes the address mark ADM, first sector mark STM1 and the second sector mark STM2 if it is disposed at i ~I i, -zj;i:ii ii

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I I the third to fourth clock period, as shown in Fig.2C, at the fourth to fifth clock period, as shown in Fig.ZD and at the fifth to sixth clock period, as shown in Fig.2E, respectively. The start position for each sector is explained subsequently by referring to Fig.13. The information indicated by the first pit Pa may be discerned by checking the position of the maximum amplitude value of the reproduced RF signal by detecting the maximum value of the difference, that is by the so-called differential detection method, as shown for example in Fig.3.

Since the first pit Pa at the leading end of the servo area ARs gives the information specifying the address mark ADM, first sector mark STMI and the second sector mark STM2, it is unnecessary to record the sector number or the track address on the sector basis.

In the address segment ASEG, an access code ACC composed of 16-bit track addresses [A3] and [AL] and the parity and a frame code FRC, composed of frame addresses [FM] and are pre-recorded as pits in the gray code as the position information along the radius of the disc and as the position information along the tangential direction of the disc, respectively, as shown in Fig.4. The 16 bits of the track address of the access code ACC are divided into groups each made up of four bits, and converted by table conversion based upon a gray code table shown in Fig.4 in the sequence of AM 15 to 12 bits (MSN), A2 =11 to 8 bits (2SM), A3 7 to 4 bits (3SM) and AL t.-1 t I i r~r~

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i: -i '.f I I sr 17 3 to 0 bits (LSN). If and only if the lowermost one of the four bits is each of the next following four bits is its complement. Thus these access codes are changed only -by. one pattern between neighboring tracks. The access codes a-re" classified by the bit positions of the access codes into groups 11, 7, [14, 10, 6, [13, 9, 5, 1] and [12, 8, 1, O] and a parity which becomes 1 when the number of bits in each group [15, 11, 7, [14, 10, 6, [13, 9, 5, 1] and [12, 8, 4, 0] is even is recorded.

Thus, by using a 1' complement for each of next 4 bits only if the lower most bit of previous four bits is so that these access codes are changed by only one pattern between neighboring tracks, the center one clock region bit is formed for in which a pit indicating the gray code of the upper two bits and a pit indicating the gray code of the lower two pits are at the shortest distance, and for in which one is at the shortest distance and the other is at the longest distance, so that the center'one-clock area does not become a continuous mirror area in the radial direction and hence the resin flow may be uniformed during disc molding to render it possible to mold a disc of high quality.

shows a portion of the access code ACC.

As for the frame code FRC, the information in the tangential direction of the address segment ASEG, that is the 8-bit frame address specifying the frame number, is divided into upper four i

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bits and lower four bits, with the upper four bits FM 7 to 4 bits (MSN) and the lower four bits LM 3 to 0 bits (MSN), are recorded -in the from of gray code in the same way as for the access codes explained above. Although the 8-bit information can be recorded as the frame codes, there are only the values of 0 to 99 of the number of the address segments ASEG.

Meanwhile, a focus sample area ARfs of the servo area ARs is the mirror portion.and is used in the optical disc driving device for focusing servo, read power APC (automatic power control) or RF signal clamping. The positions of various sample pulses for theses operations are difficult to identify correctly, such that variations not larger than ±5 servo clock pitches may be estimated. Thus the mirror portion has an area of 6 clocks as a space for sampling with a correct value without being affected by level modulation of RF signal level by pits despite these variations.

On the other hand, the data area ARd of the data segment DSEG is made up of the data area ARd of 176 to 368 data clocks for recording user data, a pre-write area ARpT of 12 data clocks and a post-write area ARp, of four data clocks, as shown in Fig.6. The number of data clocks is changed with zones. The pre-write area ARp is provided as a clamp area for securing a distance necessary for pre-heating since start of laser illumination by the driving device until the disc reaches a stable temperature for recording in case the disc is a MG disc s 1 j

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r; r ;I ;;1 i i -~nl rLi 19 and for suppressing variations in DC due to double refraction of MO signals. For assuring format interchangeability, the ROM disc is also provided with the pre-write area ARp. The post-write area ARP is provided for assuring a distance for eliminating insufficient erasure of recorded data and for avoiding interference of data otherwise caused by the edge of the groove I Ge provided on the MO disc. The MO disc is unidirectionally bulk-erased at the time of shipment- By recording data of the same magnetic properties as those in the bulk erasure direction on the pre-write area ARTp, recorded data remains unchanged even if data cannot be correctly recorded on the pre-write area ARp due to insufficient residual heat of the recording medium, so that stable signal may be reproduced. In addition, it is I effective to provide a data string stabilized at a constant value for decoding from rear data in viterbi decoding by recording the S same data of four data clocks in the post-write area ARp.

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Fig.6 shows the case of a MO disc. In the case of the ROM disc, the groove Gr in Fig.6 is deleted.

r Since stable signals may be produced when clamping is performed during reproduction using the pre-write area APp,, an accurate clamping operation may be performed.

It is noted that, since no pits are pre-formed in an area I for data re-writing, the mirror area width is larger than with Sthe replay-only optical disc in which both data and pits are prerecorded as pits. Therefore, by providing a groove Gr in an area b i'

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~1 i:a b---~4c~c~cc, corresponding to the data area ARd, as shown in Fig.6, it becomes possible to diminish the mirror portion to alleviate ill effects of disc molding on servo pits. Since the groove Gr is not employed for tracking control, it is not required to be particularly precise. In the present embodiment, the groove has a depth of 1/8, where A is the laser wavelength. With the replayonly ROM disc, the anchor pit Pan having a region of 3 data clocks is provided at a leading portion of the data area ARd, as shown in Fig.7, the mirror portion may be diminished to alleviate ill effects of disc molding on servo pits.

Each data sector is made up of 66 bytes of reference data, 2048 bytes of user data (DO to D2047), 256 bytes of ECC (El, to E16 16), 8 bytes of CRC (CRC 1 to CRC 8) and 40 bytes of user defined data totalling at 2418 bytes, as shown in Figs.8 and 9. The data format for 2352 bytes, excluding 66 bytes of the reference data, is shown in Fig.9.

Referring to Fig.i0, showing the waveform of playback signals of the reference data, four blocks, each consisting of 4 bytes of ST patterns and 12 bytes of 2T patterns, and 2 bytes of all Os as allowance for setting the detected information, are recorded as the reference data. The 8T pattern is employed for setting the three-value level (high H, mid M and low L) for data detection in viterbi decoding and partial response while the 2T pattern is used for correcting the de-derived pit position shift, caused by recording power variation, during

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reproduction.

In the data area ARd of the data segment DSEG, data other than the 66 bytes of reference data are scrambled. The scrambled data are NRZI converted and recorded on the segment basis In addition, this optical disc is a so-called zone CAV disc, and is made up from the outer rim part of a gray code part area of 736 tracks, 2-track buffer track, 5-track control track, 2track buffer track, 5-track control track, 848 track user zone 0, 864-track user zone 1, 880-track user zone 2, 912-track user zone 3, 944-track user zone 4, 976-track user zone 5, 1024-track user zone 6, 1056 track user zone 7, 1120 track user zone 8, 1184 track user zone 9, 1216 track user zone 10, 1296 track user zone 11, 1392 track user zone 12, 1488 track user zone.13, 1696 track user zone 14, 770 track user zone 15, 5-track test track, 2-track buffer track, 5-track control track, .2-track buffer track and 820-track GCP area, as shown in Figs.11 and 12.

If, with the number of tracks Tz in a zone, the number of Sdata segments Dsz required for a sector in a zone, and the number of data segments per track of Dt, the sector is to be completed from zone to zone, and the number od sectors is to be constant, if suffices to decide the number of tracks so that the number of sectors Sz in a zone is Sz Tz*Dt/Ssz W and .li Tz= K*Dsz 'I f; 22 All parameters may be obtained by allocating the approximate data capacity per zone, obtained on dividing the data capacity of the entire disc by the total number of zones as the value of K, from the outer rim side zone, and determining the data clock frequency so that the recording density of the inner most track of the zone will not exceed a pre-set density. The sector capacity is assumed to be constant at 2352 bytes.

In this case, a sector is started at a certain segment, the sector is terminated if the number of segments making up one sector is terminated and the next sector is started as from the next segment without starting the next sector at a redundant byte, if any, present in the last segment, as shown in Fig.13.

Thus a sector may be constituted in which a segment 0 of the frame code 0 is at the leading end of a zone. If a parity sector is provided for a number of sectors, the capacity of a parity sector may be rendered constant by uniforming the number of *oo- sectors for each zone.

The number of sectors in the inner most zone is likely to be the not the same as the number of the other zone by reason of the recording area. Thus the track in which the sector is terminated at the segment 1399 is to be the inner most zone.

The optical disc has the user zone divided into 16 zones as described above and the number of data bytes per segment (bytes/seg) and the number of segments per sector (seg/sector) iH are determined by data clocks DCK generated by multiplying the D B ^fc- s-y- se~vo clock SCK by XN/N where M is -he value of the clock in Fig. 11 and N is equal to 24. That Is, if the number ot se-arvo0 clocks in, the s'-vo a-eaARs is -N a nd tedata clocks DCK is the servo Clock SC'K times M/N, the n u,ibe ZcOf servo clockIs SC'Kseg= and: the numoer o: data clocks DCKseS in one segmnent are gri vean respectively by S CICse9g =9N. and DCKse- SC~segiM/N, where H- and N are integers.

M~eanwhi.le. each track is divided into 1400 segmenlts..-. of which 1300 segments are data segments DSEG. In the GCP area, the user data is nrot recorded. Therefore, 10o h segments DSEG are used as GCP segment GCPse= for storing the GCP information such as media information. The CCP segment GCPseg- is allocated to a data segment at a mid position of each address segment ASEG as shown in Fig14- The GCO0 segment G-C~se- is made up of the servo area ARs, the GCP area ARgco and'a blank ARbik, as shown in Fig 15. in the C area AR.co, there are recorded by pits s even 4-bit data coded in the gray code representation in the same .cay as for the access code ACC for the address segment ASEG, namely the C codes CGCPH], [GCPZ], [COCPS] and [GCPL] and parity [PI and page rnumbers [?ONHI and [PNL].

To the GC code is appoended the parity in order to permit error detection. The page numbers [PNRI and [PNL] are

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t also appended in- order to give plural iforMat-on data on media o r the like as thea GC? i n-forma t ion. Iff the uage numbers [PINHI and [PNLj are up *to 16 pages, the same i-fln :omat ion may be aecorued as PjNHi and PN L fao rovi di-ng pottc t~f ag=ainst rro rs By arrangin.- Lie a s u ac ie CC? segments GU~se__ Ina h state if nwruZch lower one digit numbarcof trea address teocdi the address segment A S EG (fr amea num ber) is Coinc eft w ith the page number of the C seagment CCUseg. as shown in Fig. S, -readout errors- in the page number of th a C segment GCPseg may be e!lminated. Since there are 100 frames- in each t_-ract, turn, pages or !0 sorts o F7 the CCP inorm.ation may be. repeatedly recorded ten tines for reducing th opportunity of mlsre~iding o f the ten sorts-of thelCCP i n fo r ra t As for the C information recor-ac on rC 0 sgmn CC seg.. the_ page number 0 ste ai~ 5 A lh media inomannid Dvo asho-.:n I nebts 15- to 14, .ive t he in foar mtion- cocern in th1e- phys ic a x ~omat o ti m_ a such as' It he -6os sib Iar a ~s an of- the groove'.or: zect mnarks, the bi-ts 7I to, 4 g ive the. in ormation as to P~V such- aPs 'Mo or ROM and bits 3 to 0 give LO el~nrtin inftrmat ion.

T he GCP informati on qfr the pg numbe r I ts tne L fo0rm ation specifying the, data I n farm tionjra corection form, as shown.

in~~iv 'iJ~~h it~5t he data lnformati-on speciryin= Lhe samrl-ei servo system-, logijcal- C.;yV or NqRZIT cod ing etc- and bits

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dr~ 25 7 to 0 give the information specifying the error correction codes.

The GCP information of the page number 2 is the information specifying the outer rim SFP track physical address and the bits to 0 give the information specifying the physical address of the outer rim side control track, as shown in Fig.19.

The GCP information of the page number 3 is the information specifying the inner rim SFP track physical address and the bits to 0 give the information specifying the physical address of the inner rim side control track, as shown in The GCP information of the page number 5 is the information specifying the outer rim control track clock ratio/number of segments per sector as shown in Fig.22. Bits 15 to 8 give the information specifying the number of clocks of the outer rim control track, that is the value of the clock M of Fig.11 and bits 7 to 0 specify the information specifying the number of segments per sector.

The GCP information of the page number 6 is the information specifying the inner rim control track clock ratio/number of segments per sector as shown i;n Fig.23. Bits 15 to 8 give the information specifying the number of clocks of the outer rim control track, that is the value of the clock M of Fig.11 and bits 7 to 0 specify the information specifying the number of segments per sector.

The GCP information of page number 7 is the information ;I

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'"t I.t -i specifying the number of cocks per segment/number of servo clocks per segment, as shown in Fig.24. Bits 15 to 8 give the information specifying the number of clocks per segment and bits 7 to 0 give the information specifying the number of servo clocks per segment.

The GCP information of page number 8 is the information specifying the number of segments per track, as shown in Bits 15 to 0 give the information specifying the number of segments per track.

The GCP information of page number 9 is the information specifying the number of address segments per track/spare, as shown in Fig.26. Bits 15 to 8 give the information specifying the number of address segments per track and bits 7 to 0 is the spare information.

On the control track are recorded the above-mentioned byte GCP information, laser wavelength, reflectance or track pitch, 10 bytes of media information, the number of bytes or various physical tracks or data fields, number of data clocks of various areas, and number of zones, and 320 bytes of the band information such as zone definition data.

By recording the information A specifying the number of tracks per track (1 byte) (A number of segment/track), the information B specifying the start track number of each zone (2 bytes), the information specifying the total number of tracks of each zone (2 bytes) and the information D specifying the number '4 i P 27 of segments per sector (1 byte) (D number of segments/sector), the physical track address or the physical segment address may be found from the serial sector address in the following manner.

That is, by converting the serial sector address into zone number E and offset number F using a table, and by executing an operation F x D/A G (product) H (remainder) from the offset number F, the physical track address and the physical segment address may be calculated within the zone by i Physical track address B G Physical Segment Address H As described above, with the optical disc of the embodiment S illustrated, the address mark ADM or the sector marks STM1 and STM2 are recorded in the servo area ARs. the information S" specifying the address segment ASEG or the leading end of the sector may be given without increasing redundancy of the data area ARd. Since each sector mark STM1, STM2 specifies the leading end data segment DSEG of the sector or a segment directly before the leading end data segment, the sector is not defective even if one of the sector marks is defective, thus lowering'the rate of occurrence of defective sectors.

With the above-mentioned optical disc,, by recording servo pits having a length corresponding to two clocks with respect to the generated servo clocks SCK in the servo area ARs, the mirror portion in the servo area ARs may be reduced, thereby reducing rr; i i ,f ee la e I, E

J

I

.I

il 28 ghost pits generated during disc molding. By having a pit distance of not less than 5 shortest pit width, data interference may be suppressed for giving stable servo signals.

On the other hand, since scrambled recording data are recorded as NRZI modulated data on the optical disc, the recording pattern is randomized and the probability of fixed patterns being continuously generated may be lowered. Thus the disc molding may be stabilized and the memory capacity of the reproducing apparatus in viterbi decoding may be reduced.

In addition, it is possible with the above optical disc to secure residual heating time by the laser beam by the pre-write area ARp and post-write area ARp 0 provided in ten data area ARd of the data segment DSEG, so that data may be recorded positively in the data area ARd.

In the above optical disc, since the servo information and the address information are given by the servo area ARs and the address segment ASEG provided at equiangularly divided positions, the address information may be read in the playback system by servo clocks SCK produced by the servo information without regard to data recording/reproduction, thereby enabling stable high speed seeking. Since plural zones with uniform number of sectors are equal in data capacity, there is no necessity of changing the numbers of the parity sectors or exchange sectors from zone to zone, thus simplifying the control software.

On the other hand, since the last segment of a zone is :1 j: j i! ji

I

:i i i

I

i b;i j i i a r C..ir ~iZ a~i~a~ e~~L~ segments are produced. In addition, since the start segment in each zone is arranged at the same position of each track, and each zone is started from the segment of the same segment number, In addition, since the GCP area across plural tracks give the media information in the gray code with the same format as that of the address information recorded in the address segment ASEG, the decoder for detecting the address information may be used simultaneously as a decoder for exclusively reading out the media information by the reproducing apparatus. There is no zr necessity of a special signal generator during cutting. In Ue.

addition, the address information may also be read during readout n, the adadds seadofout of the GCP area by the reproducing apparatus, so that the pickup position may be managed positively.

With the optical disc, the media information specifying the sort of the medium or the format may be given by the GCP area to the reproducing apparatus.

It is also possible with the optical disc to supply the information for reading the control track information by the GCP area.

-Since the media information of the same contents are given by the GCP area for one track turn, the media information of high reliability may be given to the reproducing apparatus.

Since each segment disposed radially of each track of the SGCP area of the optical .disc gives the same media information, Sthe media information may be read out without applying tracking on the reproducing apparatus.

In addition, since the GCP area provided in the vicinity of the inner and outer rims of the optical disc gives the same media Sinformation, any of the inner rim side access start or the outer rim side access start may be selected on the side of the reproducing apparatus.

The recording/reproducing apparatus having the MO disc and ROM disc having such format is comprised of a control circuit block and a disc drive 200, as shown in Fig.27. The basic arrangement of the recording/reproducing apparatus shown in Fig.27 is the same as shown in JP Patent Application No.5-24542.

|1 With the present recording/reproducing apparatus, exchange of commands and data is executed with the host computer connected via the SCSI interface.

Processing for exchange of commands and data is by a controller 101 of the control circuit block 100. The controller 101 appends CRC and error correction codes to data from the host computer 300 during recording and transfers the data to the disc drive 200. For reproduction, data from the disc drive 200 is corrected for errors and user data portions are transferred to Sthe host computer 300. Commands to the servo system and resoective blocks of the disc drive 200 are given by a digital signal processor (DSP) 102 which performs necessary processing -2- 1 a-f j 31 responsive to commands from the controller 101.

With the present recording/reproducing apparatus, the DSP 102 is responsive to a request from the host computer 300 in the S. state in which the optical disc 201 is loaded by a loading unit 200 on a spindle motor 203 to command a spindle driver 204 via San I/O block 103 to run the spindle motor 203 in rotation. The DSP may also issue a similar command when the optical disc 201 is loaded when the automatic spin mode is set. When the spindle motor 203 reaches a pre-set rpm, the spindle driver 204 issues a spindle on/off signal SPD to apprise the DSP 102 that the rotation has been stabilized. During this time, the DSP 102 pu s shifts an optical pickup 205 by the pickup driver 105 via a pulse width modulating (PWM) circuit 104 until it is caused to bear 1 against stops 200A, 200B in the vicinity of the outer or inner rim of the optical disc 201 for positioning a beam spot in the recording area, that is in a GCP area outside the zones 0 to 15, as shown in Fig.28. If focusing is captured in the recording area, there is a risk of inadvertent data erasure if the disc is a highly sensitive disc, such as MO disc. By capturing focusing in an area having data formed by pits, such as the GCP area. outside the recording area, inadvertent data erasure may be prohibited from occurrence.

It is possible with the DSP 102 to discern whether the optical disc 201 is the replay-only optical disc or a recordable MO disc. Since the media information is recorded in the GCP area

I

3 *i 32 in- the gray code and with the same format as that of the address Tnform-aton, the address information and the media information may be read and discerned by the same method. In addition, since the medi' information in the gray code is recorded in the GCP area of plural tracks, the media information may be reliably read even if the beam spot position control is inaccurate.

When the spindle motor 203 reaches a constant rpm and the pickup 205 is moved to e.g. the vicinity of the outer rim, the DSP 102 sets a bias current LDB for a laser diode 207 provided in the optical pickup 205 for a laser driver 206 via a D/A converter 107 from the I/O block 106 and issues a command to a servo timing generator (STG) 108 controlling the on/off of the laser diode 207 to emit a laser light. The bias current LDB is S set to a high level and to a low level during recording and.

reproduction, respectively. When the laser light is emitted by the laser diode 207, the laser light enters a photodetector 208 A provided in the optical pickup 205 and a detection output by the photodetector 208 enters a multiplexor 109 as a front APC signal F-APC converted into a voltage by an I-V conversion block via a current-voltage conversion and matrix amplifier 209.

The front APC signal F-APC is digitized by an A/D converter 110 as a signal time-divisionally multiplexed by the multiplexor 109 so as to enter the DSP 102 via I/O block 111. The DSP 102 recognizes the light.volume of the laser light by the digitized j front APC signal F-APC and varies the bias current LDB based upon -now I T .r 33 the light volume-control data calculated by the enclosed digital filter for controlling the outgoing light from the laser diode 207 to be constant.

The.DSP 102 cause the current to flow from the PWM circuit 104 to the focusing driver of the pickup driver 105 for vertically driving the focussing actuator of the pickup 205 for Sfocusing search state. The laser light reflected back from the optical disc 201 is detected by the photodetector 208. A Sdetection output of the photodetector 208 is converted by an I-V conversion block of the I-V conversion and matrix amplifier 209 into a voltage which is supplied as a focussing error signal FE to a multiplexor 109.

Similarly to the front APC signal F-APC, the focusing error signal FE is digitized by the A/D converter 110 as a signal timedivisionally selected signal by the multiplexor 109 so as to enter-the DSP 102 via the I/O block 111. The DSP 103 feeds back the focusing control data obtained on digitally filtering the focusing error signal via the PWM circuit 104 to the focusing driver of the pickup driver 105 for constituting a focusing control servo loop. When the focusing control becomes stabilized, RF signals (for ROM disc) or MO signals (for data area of MO disc) from the pre-write area ARpR obtained by the I-V conversion and matrix amplifier 209 from a detection output by the photodetector 208 has its amplitude stabilized to some extent and is .converted by an A/D converter 113 into analog signals after ~I I 4 d3 4.

St -ET~n~r -p~n being clamped by a selector and clamp 112. By performing clamping using the pre-write area AR, stable signals can be produced and an accurate clamping operation may be achieved.

The A/D converter 113 is selectively fed with the servo clock signal via a clock selector 115 from a servo clock generating (SPLL) circuit 114 or a data clock signal DCK from a data clock generating (DPLL) circuit 117. The clock selector 115 is controlled by a servo timing generator (STG) 108 for selecting the servo clock signal SCK responsive to the playback RF signals from the servo area and for selecting the data clock signal DCK responsive to the playback signal from the data area.

The clocks during servo capture operation are of a frequency in the free-running state of the servo clock generating (SPLL) circuit 114. For the timing pulse during clamping, a signal obtained on frequency-dividing the servo clock signal of the free-running frequency by a pre-set value is employed.

The SPLL circuit 114 checks the amplitude of RF signals digitized by the A/D converter 113 to check a bit patterning order to search the same pattern as that of a pre-set pit row in the servo area. If this pattern is found, the window is opened at a timing of appearance of the next pattern, that is at a servo area of the next frame, and checks for possible pattern coincidence. If this operation is confirmed a pre-set number of times, the phase of the servo clock SCK generated by the SPLL circuit 114 is deemed to be locked with respect to the phase of i; -i z i, F- ji i :1 r ?i

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1 s£ a

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rotation of the optical disc. From sampling data bl, b2 of sampling points at both -ulders spaced one servo clock towards front and back from the center point of the playback RF signal waveform with respect to the wobbling pit Pb sampled at timings Tb, t, tl and t of the servo clocks and sampling data bl, b2 of sampling points at both shoulders spaced one servo clock towards front and back from the center point of the playback

RF

signal waveform with respect to the wobbling pit Pc, an operation (phase error data) [(b2-bl) is carried out for detecting the phase error of the servo clocks SCK and servo data, as shown in Fig.2 9 Thus the phase information is obtained by taking an amplitude difference at both shoulders of the wobbling pits Pb and Pc within the servo area.

The phase information derived from the two wobbling pits is added to the phase information for absorbing gain variation produced form amplitude changes due to the tracking position.

If the SPLL circuit 114 is locked, it is possible for the optical disc reproducing apparatus to recognize the scanning position of the pickup 205 on the segment basis, so that the oosition of the first pit Pa can be recognized. Fur windows

A,

B, C and D shown in Fig.3 are opened and the position which gives the maximum amplitude among the RF signals samples at the four positions A to D is searched. If the result is the position

A,

it can be recognized that the address mark is the address mark ADM and this segment is the address segment at the leading end

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i1 i> 7= "/i Ilk of the frame. Thus it becomes possible to clear an enclosed frame counter, not shown, for frame synchronization. Since each frame is made up of 14 segments, a window is opened every 14 segments. If continuous recognition as an address mark is possible, frame synchronization is judged to be locked.

On frame synchronization, the address recording position can be recognized, so that the access code ACC and the frame code FRC are decoded by an address decoder (ADEC) 116. With the ADEC 116, the pattern of four bits coded in a gray code is decoded by checking the coincidence with the gray code table shown in Fig.4.

The ADEC 116 samples the playback RF signals at positions a, b.

c and d shown in Fig.4 and finds the maximum amplitude position by a differential detection method. Similarly, the playback RF signals are sampled at respective positions e, 1, g and h shown in Fig.4 and the maximum amplitude position is found in order to effect decoding by the combination and the gray code table. By the above process, the track address [AMI] to parity and the frame address [FM] and [FL] are decoded and the decoded results are stored in a register. When the data is established, the DSP 102 reads out the decoded results stored in the register for detecting the current position of the pickup 205. Since it is not the-four bits but the entire pattern that is coded in gray code, comparison with an inverted table or a non-inverted table is executed depending upon whether the LSB of the upper four bits is l] or If, when-the initially decoded frame code FRC is

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A

r 7:; m& Ain, Rs M-P -j

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r r

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a

R

i r- loaded on a frame counter, and a number obtained on incrementing the frame counter on the frame basis is compared to the actually reproduced frame code FRC, continuous coincidence is confirmed.

rotation synchronization is deemed to be established.. By returning the number obtained from the frame counter as the fame code FRC to the DSP 102, there is no risk of the mistaken recognition of the frame position despite some defects.-~ The ADEC 116 decodes the GCP information.in a similar manner to the track address and the frame code FRC. However, it is not the address segment but the decoded results stored in the register at the GCP segment GCPseg having the GCP information recorded thereon, that is read out. Thus the contents of the GCP area ARgcp may be confirmed.

On the other hand, the DSP 102 calculates the speed of movement of the pickup 205 as it reads the gray coded track address during seek for controlling the slide motor of the pickup driver 205 via a slide driver of the pickup 'driver 105 for the PWM circuit 104 for shifting the pickup 205 to a target track.

When the pickup 205 reaches the target track, the tracking operation is executed. The tracking error signal THE is obtained by taking a difference of the amplitudes of RF signals reproduced from wobbling pits in the servo area. The DSP 102 feedsback the.

tracking control data resulting from digitally filtering the difference value to the pickup driver 105 via the PWM circuit 104

A

;lj

V-

=-or cons t itut ing a tracking control-li sernVo loop.

The lading position of the target sector is detected while t-ractk1ing Is applied. There are the sector mark-1s STMl and STML,2 in the ledn Cement and a directlY rioSsget o ac Sector, as described above. Th e _aspecrjve sector marks STMI, STM2 onen the windows at the four positions A, 3, C and D shown fn Fi:g.3.. If the maximurm.,=_iriltudie position among the RF signals samle att~esefu oin to is B, it specifies the -leading end se4gme nt. o f the sec tor wees if the. maxiMum amplitude position is Ct" it specifie th sgmentdrcl previous to the sector. Basicially, thesgeta h edn end of the sector is determined by c~nvertin.=- the sector- -address g.iven by the hos t C ,omouter-300-- into. a'physical sector and-finding in which segeto ih track theen sewtoizis located. The probability% of thLe' ktw kiads of sector ma~zrks becomping simultaneously' defective' is aimp i c&1l not' h ighe'r t han such! that thirbblt focrece o f deectie secrs is -extreIl smallI i -'~daa 5lo;. crata n ~ruit (DPLL) c Creuitl 11 7 7 geeatsdata ;Aoc h~C~bcf~ utpyn~h,~raffi .S Tic hrbn izea ser vo- c o ck s SCK o t- 'ned the SPLL ci rcu it 114 by ansends th at c Dck tian; generator 19 and A recording renbroducings c rculL The:i data clocks, .DCK generated bXy t he da Ia coc -ene rat-ing circuit (DPLL) l17 1 are p3hase-compensated b Iy a read clock. phas& compensaQ ti-on (RCPC) I 17

F-

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1~ i- 9 ii ;i f Si:; '-ii l;"~s ai~j ~c7; iur circuit 121 based upon the phase in the read phase clock compensation area of the playback RF signals of the reference data shown in Fig.L0.

The recording/reproducing circuit 120 is fed during the recording mode with user data via the controller 101 from the host computer 300. The recording/reproducing circuit 120 has a scrambling circuit having the constitution shown in The scrambling circuit shown in Fig.30 is made up of a 7stage flipflop 131, a first adder 132 for EXORing the outputs of the first and last stages of the flipflop 131 for feeding back the result to the-first stage of the flipfloo 131 and a 'second adder 133 for EXORing the output of the first adder 132 and the recording data. By the flipflop 131 being cleared at each sector start timing, the scrambling circuit generates random numbers of 127 periods shown in a scramble table of Fig.31 as an output of the first adder 132. On the other hand, by the second adder 133 EXORing.the recording data and the random number, the scrambling circuit performs scrambling on the sector basis in accordance with Y X X 1.

The recording/reproducing circuit 120 modulates the scrambled user data into NRZI data synchronized- with the data clocks DCK. The initial value of each segr.ent is set to The modulated signal WDAT is fed via a magnetic head driver 210 to a magnetic head 211. The magnetic head 211 generates a magnetic field conforming to the modulated signal WDAT and

I:-

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:5 i c; ~i"l I; I I-i 1": -i '7C; Z ;T l: i I- L ril;; n r; ig:l~ i ii applies the,magnetic field to the data area ARd of the MO disc 201 superheated to the Curie temperature by a laser beam generated by the laser diode 207 for recording the NRZI data.

During recording, the laser drier 20S is controlled by the servo timing generator (STG) 108 so-that the laser diode 207 will be switched from the playback driving power to the recording drivi-ng power. at. a timing of movement of the pickup 205 from the servo area to the pe-write area of the data area. The recording/reproducing circuit 120 is controlled by the data timing generator (DTG) 119 so that data of a specified polarity will be recorded in the pre-write area ARpR at a timing the optical pi-ckup 205 traverses the pre-write area ARPR. The data of the specified polarity means data of the-same polarity as that of bulk erasure of the pre-write area ARpR. By recording data of the same polarity as the bulk erasure direction on the pre-write area AR R, recorded data is not changed even if data is not regularly recorded on the pre-write area ARpR due to insufficient residual:heat of the medium, so that stable signals may be reproduced.

Durihg playback mode operation, the playback MO signal obtained by the I-V conversion and matrix amplifier 209 from the.

detected-loutput by the :photodetector :208 is converted into digital signals by the A/D converter 113 so as to be supplied to the recordoing/reproducing circuit 120. The -recording/reproducing circuit 120 decodes the NRZI data by i.

1 q

N

i; I 1 i L i -L i -iterbi decoding after digitally filtering the playback MO signals digitized by the A/D converter 113 in conformity to ;artial response The NRZI data is converted on the segment basis into the NRZI data which are descrambled on the sector basis into playback data which is transmitted via the controller 101 to the host computer 300.

The MO disc device employing partial response and viterbi decoding has been shown in our JP Patent Publication 225638.

1

CI

XI

By scrambling recording data. in this manner,, the data pattern is randomized so that the probability of the continuation of a data string having unified values at the time of decoding is small while the memory capacity for viterbi decoding may be reduced. In-addition, since the bit array is randomized for the ROM disc, the bit presence/absence ratio on the disc approaches 50% thus facilitating disc molding.

With the present recording/reproducing apparatus, the concentrically or spirally extending track is divided into plural sectors comprised of plural segments composed of the servo area ARs and the data area ARd, and the address mark specifying the address segment ASEG having the track address recorded thereon, the data segment DSEG having the data of the leading end of the sector recorded thereon and the sector mark specifying the directly previous segment, are recorded in a servo area of a MO disc, in which the address mark and the sector marks recorded on F i

I

A.

SIP~L~pC~ -CIC -sC6- II i_: 42 :he servo area ARs are detected by maximum differential value detection by reproduced signals of the servo area by recording/reproducing means for recording/reproducing data on or from the target sector.

The recording/reproducing apparatus reads out the media information in the gray code pattern with the same format as the address information of the address, segment ASEG and reads out the control information from the control track based upon the media information for performing control based upon the control information.

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Claims (6)

1. An optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, wherein each segment has a data area and a servo area, the servo area including: servo pits containing servo information to be read by a corresponding optical disc drive; and a discrimination mark which, by means of its position within the servo area, identifies the segment in which the corresponding servo area is disposed.

2. An optical disc according to claim 1, wherein the segments are data Ssegments for recording user data and address segments for specifying an address associated with one or more corresponding data segments, said discrimination mark discriminating the data segment from the address segment.

3. An optical disc according to claim 1 or claim 2, further including a V; plurality of sectors, each defined by a plurality of segments, wherein a leading segment at a leading end of each sector is identified by the discriminating mark.

4. An optical disc according to claim 3, wherein an adjacent segment directly previous to the leading segment in each sector is identified by the discriminating mark. An optical disc according to claim 4, wherein the adjacent segment is further identified by the discriminating mark.

6. An optical disc including a plurality of substantially concentric tracks, -i3 each track defining a plurality of segments, each segment having: n:AibeIO1 622.doc:EC

44- a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and i-c a data area; Swherein at least some of the segments are data segments for recording user s data, and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, the data area of each address segment including address information recorded in gray code representation using a region of five clocks of a clock signal generated by a disc drive based upon the servo pits, for 2-bit information. 7. An optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and 15 a data area; wherein at least some of the segments are data segments for recording user data, and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, the data area of each S address segment including address information recorded as pits representing a 4-bit S 20 gray code representation in an 11-clock area based on a clock signal generated by a disc drive based upon the servo pits, each address segment having: a first area corresponding to 5 clocks for representing an upper two bits of the F 4-bit gray code representation; a second area corresponding to 5 clocks for representing a lower two bits of the 4-bit gray code representation; a third area disposed between the first and second areas and corresponding to 1 clock, the third area including a pit when: t n:\libe\01622.doc:SEC ~D~BIPIIII pits representing the respective upper and lower two bits of the 4-bit gray code representation are at a minimum distance from the third area; or one of the pits representing the respective upper or lower two bits of the 4-bit gray code representation are at the shortest distance from the third area at the minimum s distance from the third area and the other of the respective upper or lower two bits of the 4-bit gray code representation are at a maximum distance from the third area. a i r I I r .c r. r i i g. a rr I ci r II lr 8. An optical disc according to any one of the preceding claims, wherein plural servo pits are recorded in said servo area so as to have an area of two clock o1 signals and to extend over a distance of not less than five pits. 9. An optical disc according to any one of the preceding claims, wherein scrambled and NRZI converted data is recorded in said data segment. '5 10. An optical disc according to any one of claims 2 to 9, further including a pre-write area at a leading end of the data area of the data segment, the pre- write area having data of a predetermined polarity recorded therein. 11. An optical disc according to any one of claims 2 to 10, further 20 including a post-write area at a trailing end of the data area of the data segment, the post-write area having data of a predetermined polarity recorded therein. 12. An optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and a data area; !A n:\IibelOI 622.oc:SEC r r r n i I r I I I i -46 wherein the optical disc is divided into a plurality of zones, each of which has a uniform number of sectors and a plurality of successive tracks, wherein a number of servo clocks SCKseg per segment and a number of data clocks DCKseg per segment are determined by the relationship: DCKseg SCKseg M/N, where M and N are integers. 13. An optical disc according to claim 12, wherein SCKseg 9N. 14. An optical disc according to claim 12 or claim 13, the start positions of radially adjacent zones being radially aligned, wherein each zone commences at the start of a new segment, even if there is a redundant area in the last segment of an immediately previous zone. An optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and a data area; wherein at least some of the segments are data segments for recording user 20 data, and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, the data area of each address segment including address information recorded in gray code representation, and wherein media information, coded in the same gray code representation as the address information, is recorded in a media information area within the data areas 2s associated with at least some of the tracks. 16. An optical disc according to claim 15, wherein the media information area is formed across a plurality of consecutive tracks. i' S I i' i-i i:M S. n:%fibeX01 622.dcc:SEC ,4. @1 S47 17. An optical disc according to claim 16, wherein similar media information is recorded in each data area of the same angular position of the consecutive plural tracks. 18. An optical disc according to claim 17, wherein the media information area is provided at regions adjacent the inner and outer edges of the optical disc. 19. An optical disc according to claim 15, wherein said media information 1o is recorded in each data area of a portion of said tracks. 20. An optical disc .according to claim 15, wherein the address information is recorded in the address segment as gray code using an area corresponding to five clocks of a clock signal generated by a disc drive based on said servo pit, 2-bit information. 21. An optical disc according to claim 15, wherein said address information is recorded as pits in a 4-bit gray code representation in an 11-clock area of said clock signals in said address segment, said address segment having: a first area corresponding to 5 clocks for representing an upper two bits of the 4-bit gray code representation; a second area corresponding to 5 clocks for representing a lower two bits of the 4-bit gray code representation; and a third area disposed between the first and second areas and corresponding to 1 clock, the third area including a pit when: pits representing the respective upper and lower two bits of the 4-bit gray code representation are at a minimum distance from the third area; or t 'X i r i i 6 i i; Il.:i- i 5 i r. i: -rt- -2 rcU--' rl-- r S~n.~FF 1~ c~i i I* B~sCII~ l l--1 21-- f, 19 -48- one of the pits representing the respective upper or lower two bits of the 4-bit gray code representation are at the minimum distance from the third area and the other of the respective upper or lower two bits of the 4-bit gray code representation are at a maximum distance from the third area. 22. An optical disc according to any one of claims 15 to 21, wherein said media information indicates that the optical disc is of either a writable type or a replay- only type.: 23. An optical disc according to claim 15, wherein similar media information is recorded in each data area of the same angular position of the consecutive plural tracks. 24. An optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, each segment having: a servo area including servo pits containing servo information to be read by a corresponding optical disc drive; and a data area; wherein at least some of the segments are data segments for recording user data, and at least some of the remaining segments are address segments aligned radially on the optical disc with other radially adjacent address segments, further including a media information area formed in a plurality of tracks adjacent the inner or outer edges of the optical disc, the media information area containing media information stored in a gray code representation. An optical disc driving device for driving an optical disc, the optical disc including a plurality of substantially concentric tracks, each track defining a A) r. r' r: i- n:UibAOI622.doc.SEC -49- i 4 I a w i r r ~I 'F. i i' :I plurality of segments, wherein each segment has a data area and a servo area, the servo area including: servo pits containing servo information to be read by the disc driving device;- and a discrimination mark which, by means of its position within the servo area, identifies the segment in which the corresponding servo area is disposed wherein the optical disc driving device includes: reproducing means for reproducing information stored on the optical disc; detection means for detecting the position of said discrimination mark from a to signal produced by said reproducing means from the discrimination mark by a differential detection method; and discrimination means for discriminating the segment based upon the results of detection by said detection means. is 26. An optical disc driving device for driving an optical disc, the optical disc including a plurality of substantially concentric tracks, each track defining a plurality of segments, wherein each segment has: a data area; a servo area including servo pits containing servo information to be read by the disc driving device; and a single polarity pre-write area disposed at an end of the data area; the optical disc o2 driving device including: recording/reproducing means for reproducing data from the optical disc and for recording data to the optical disc; driving power applying means for applying a low-level reproducing driving power or a high-level recording driving power to said recording/reproducing means; data supplying means for supplying recording data to said recording/reproducing means; and control means for selectively controlling: 4P t P. r- n:\hbe\01622.doc:SEC '~cYk< I9 said driving power applying means when an optical pickup of the recording means is moved from said servo area to said pre-write area of said data area, such that the driving power is switched from the reproducing driving power to the recording driving power; s said data supply means for supplying data to the optical pickup when the optical pickup is moved from said servo area to said pre-write area of said data area: the data being of the same polarity as the polarity of the pre-write area; and said data supply means for supplying desired data to said optical pickup when said pickup traverses said pre-write area during recording. 27. An optical disc driving device according to claim 26, further including clamping means for clamping said data reproduced by said recording/reproducing means when reproducing from said pre-write area. is 28. An optical disc substantially as hereinbefore described with reference to the accompanying drawings. 29. An optical disc driving device substantially as hereinbefore described with reference to the accompanying drawings. DATED this Eleventh Day of September 1998 Sony Corporation Patent Attorneys for the Applicant SPRUSON FERGUSON i. t: j t 1 i. r r i r~ J I i 1 rniIiW\016224ac:SEC nl1iba\01622.doc:SEC