DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

[0046] According to a first embodiment of this invention, a signal is recorded on and reproduced from an optical disc while the disc is scanned by a recording laser beam or a reproducing laser beam. The scanning of the disc by the laser beam is on a CLV (constant linear velocity) basis. The constant linear velocity relating to the scanning of the disc can be selected from a predetermined normal velocity and at least one predetermined high velocity. The normal velocity is equal to, for example, 3.49 m/s. The high velocity is equal to an integer multiple of the normal velocity. The first embodiment of this invention is designed to correct a recording laser beam into an optimal waveform in accordance with the type of an optical disc and a change in the linear velocity relating to the scanning of the disc.

[0047] As shown in FIG. 1 , data to be recorded, that is, 8-16 modulation-resultant input data, repetitively change between a high level state and a low level state. The input data continuously in the high level state correspond to a recording mark on an optical disc. The input data continuously in the low level state correspond to a space between recording marks on the optical disc. A laser beam for writing information on an optical disc (for example, a DVD−RW) is modulated into a recording waveform in accordance with the input data. A clock signal (a bit clock signal) related to the input data has a period T. The period T is also indicated as T. The input data in FIG. 1 have a time-domain portion with a mark length of 8T, and a time-domain portion with a mark length of 3T. According to the laser-beam recording waveform which corresponds to the 8T mark portion or the 3T mark portion of the input data, the power (or the intensity) of the laser beam changes among a recording level Po, an erasing level Pe, and a bias level Pb. The recording level Po is greater than the erasing level Pe. The erasing level Pe is greater than the bias level Pb.

[0048] As shown in FIG. 1 , for the 8T mark portion or the 3T mark portion of the input data, the power of the laser beam initially remains equal to the erasing level Pe during a certain time length and then rises to the recording level Po to form a first positive-going pulse. Thereafter, the power of the laser beam alternately changes between the recording level Po and the bias level Pb to form a second positive-going pulse or second and later positive-going pulses referred to as multiple positive-going pulses. Preferably, the second and later positive-going pulses have a same width. At the end of the 8T mark portion or the 3T mark portion of the input data, the power of the laser beam drops from the recording level Po to the bias level Pb, and the last positive-going pulse terminates. The last positive-going pulse is followed by a negative-going pulse serving as a cooling pulse. Specifically, after the end of the 8T mark portion or the 3T mark portion of the input data, the power of the laser beam remains equal to the bias level Pb during a certain time length and then rises to the erasing level Pe to form the cooling pulse.

[0049] With reference to FIG. 1 , during the first T range of the 8T mark portion or the 3T mark portion of the input data, a positive-going pulse is absent. There is one positive-going pulse corresponding to each of the second and later T ranges of the 8T mark portion or the 3T mark portion of the input data. The bias level Pb is equal to a reproducing level in the case of a DVD−RW. A strategy for optimal recording which relates to recording pulse timings is designed to optimally decide the width Ttop of the first positive-going pulse, the width (the duty cycle) Tmp of the second and later positive-going pulses, and the width Tc1 of the cooling pulse. For mark portions of the input data which differ from the 8T mark portion and the 3T mark portion, the power of the laser beam is controlled similarly to the previously-mentioned laser-power control for the 8T mark portion and the 3T mark portion.

[0050] In the case of a DVD−R (an optical disc), the laser-power-related parameters are modified from those for a DVD−RW. Specifically, the erasing level Pe is changed to the reproducing level (the bias level Pb), and every cooling pulse is removed. The laser-power-related parameters for a DVD−R may be similar to those for a DVD−RW.

[0051] In the case of a DVD−RW, the multiple-pulse-like change of the laser-beam power between the recording level Po and the reproducing level (the bias level Pb) may be replaced by a laser-power control profile causing the laser-beam power in an intermediate time range to be lower than those in first and last time ranges for every mark portion of the input data. This design also provides a strategy for optimal recording. The level of the laser-beam power in the intermediate time range is optimally decided. Furthermore, the timing of drop of the laser-beam power for the intermediate time range is optimally decided.

[0052] The laser-power-related parameters for a DVD+RW (an optical disc) are similar to those for a DVD−RW. The laser-power-related parameters for a DVD+R (an optical disc) are similar to those for a DVD−R. The laser-power-related parameters for a Blu-ray-standard disc are similar to those for a DVD−RW.

[0053] A DVD−R or a DVD−RW has a lead-in area and a data area on which information can be recorded. In general, the lead-in area and the data area correspond to an information management area and an information recording area, respectively. The lead-in area and the data area are formed with an information-recording groove track which wobbles at a constant frequency. When the normal linear velocity relating to the scanning of the disc is equal to 3.49 m/s, the wobble frequency is equal to about 140 kHz. In the lead-in area and the data area, lands between grooves or groove portions have land pre-pits (LPPs) representative of address information and management information. Land pre-pits are disclosed in, for example, Japanese patent application publication number P2001-148124A or P2001-312823A.

[0054] A signal recorded on an optical disc such as a DVD−R or a DVD−RW is divided into ECC blocks. One ECC block is a minimum unit of error correction. Also, one ECC block is a minimum unit for the signal reproduction from and the signal recording on the optical disc. Each of units composing the information represented by the LPPs corresponds to one ECC block, and has an information piece representative of an address and other information pieces. The units composing the LPP information are referred to as fields classified by a field type ID (a field type identifier). The field type ID can change among ID0, ID1, ID2, . . . A field of a type corresponding to a field type IDk is called a field IDk, where IDk=ID0, ID1, ID2, . . . As will be made clear later, every field is composed of 16 frames.

[0055] FIG. 2 shows the format of an LPP-information field system for an optical disc designed to be scanned at only the normal linear velocity. As shown in FIG. 2 , there are fields of six types denoted by ID0, ID1, ID2, ID3, ID4, and ID5 respectively. A field ID0 stores an information piece representative of the address of a corresponding ECC block, and other information pieces. Generally, the field ID0 is recorded on a data area of the disc. A field ID1 stores an information piece representative of the address of a corresponding ECC block, an application code, and other information pieces. The field ID1 is recorded on a lead-in area of the disc. A field ID2 stores an information piece representative of the address of a corresponding ECC block, an OPC recommended code/write strategy code “1”, and other information pieces. Here, OPC means “optimum power control”. The field ID2 is recorded on the lead-in area of the disc. A field ID3 stores an information piece representative of the address of a corresponding ECC block, a production ID “1”, and other information pieces. The field ID3 is recorded on the lead-in area of the disc. A field ID4 stores an information piece representative of the address of a corresponding ECC block, a production ID “2”, and other information pieces. The field ID4 is recorded on the lead-in area of the disc. A field ID5 stores an information piece representative of the address of a corresponding ECC block, a write strategy code “2”, and other information pieces. The field ID5 is recorded on the lead-in area of the disc.

[0056] FIG. 3 shows the format of an LPP-information field system for an optical disc designed to be scanned at a linear velocity selectable from the normal linear velocity, a velocity equal to twice the normal linear velocity (the 2-fold linear velocity), . . . , and a linear velocity equal to “m” times the normal linear velocity (the m-fold linear velocity), where “m” denotes a predetermined natural number equal to or greater than 4. For example, the disc scanning linear velocity can be selected from the 1-fold linear velocity (the normal linear velocity), the 2-fold linear velocity, the 4-fold linear velocity, the 6-fold linear velocity, the 8-fold linear velocity, the 12-fold linear velocity, the 16-fold linear velocity, and the 24-fold linear velocity. As shown in FIG. 3 , there are fields of different types denoted by ID0, ID1, ID2, . . . , IDn, and IDn+1 respectively. Fields ID0, ID1, ID2, ID3, ID4, and ID5 in FIG. 3 are similar to those in FIG. 2 . With reference to FIG. 3, a field ID2 stores an information piece representative of the address of a corresponding ECC block, an OPC recommended code/write strategy code “1” for the scanning of the disc at the normal linear velocity, and other information pieces. A field ID5 stores an information piece representative of the address of a corresponding ECC block, a write strategy code “2” for the scanning of the disc at the normal linear velocity, and other information pieces. A field ID6 stores an information piece representative of the address of a corresponding ECC block, an OPC recommended code/write strategy code “1” for the scanning of the disc at the 2-fold linear velocity, and other information pieces. The field ID6 is recorded on the lead-in area of the disc. A field ID7 stores an information piece representative of the address of a corresponding ECC block, a write strategy code “2” for the scanning of the disc at the 2-fold linear velocity, and other information pieces. The field ID7 is recorded on the lead-in area of the disc. Similarly, a field IDn stores an information piece representative of the address of a corresponding ECC block, an OPC recommended code/write strategy code “1” for the scanning of the disc at the m-fold linear velocity, and other information pieces. The field IDn is recorded on the lead-in area of the disc. A field IDn+1 stores an information piece representative of the address of a corresponding ECC block, a write strategy code “2” for the scanning of the disc at the m-fold linear velocity, and other information pieces. The field IDn+1 is recorded on the lead-in area of the disc.

[0057] FIG. 4 shows the details of a field ID0 which is listed in FIG. 2 or FIG. 3 . In general, the field ID0 is recorded on the data area of the disc. With reference to FIG. 4 , the field ID0 is divided into 16 frames assigned numbers of “0”, “1”, . . . , and “15” respectively. In the field ID0, the frames having numbers of “0”, “1”, and “2” store an information piece representative of the address of a corresponding ECC block. The frames having numbers of “3”, “4”, and “5” store an information piece representative of the parity of the ECC-block-address information piece. The frame having a number of “6” stores an information piece representative of a field ID value (a field identification value). The frames having numbers of “7”, “8”, and “9” store an information piece representative of the address of the corresponding ECC block. The frames having numbers of “10”, “11”, and “12” are reserved. The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of the ECC-block-address information piece. Thus, the field ID0 duplicately stores the information piece representative of the address of the corresponding ECC block.

[0058] As shown in FIG. 4 , the 16 frames of the field ID0 are separated into two groups referred to as a part “A” and a part “B” respectively. The part “A” contains an information piece representative of the address of a corresponding ECC block, and an information piece representative of the parity of the ECC-block-address information piece. The part “B” contains an information piece or information pieces peculiar to the related field. Specifically, the part “A” stores an information piece representative of the address of a corresponding ECC block, and an information piece representative of the parity of the ECC-block-address information piece. The part “B” stores an information piece representative of a field ID value, an information piece representative of the address of the corresponding ECC block, and an information piece representative of the parity of the ECC-block-address information piece.

[0059] Similarly, each of fields ID1, ID2, . . . , IDn, and IDn+1 which are listed in FIG. 2 or FIG. 3 is divided into 16 frames assigned numbers of “0”, “1”, . . . , and “15” respectively. The 16 frames are separated into two groups referred to as a part “A” and a part “B” respectively. The part “A” contains an information piece representative of the address of a corresponding ECC block, and an information piece representative of the parity of the ECC-block-address information piece. The part “B” contains an information piece or information pieces peculiar to the related field.

[0060] The part “B” of a field ID1 stores an information piece representative of a field ID value, an application code, and a physical code. The application code has an information piece representative of general use of the disc, and an information piece representative of special use of the disc. The physical code has physical-specification information pieces including an information piece representative of the track pitch of the disc, an information piece representative of the linear velocity relating to the scanning of the disc, an information piece representative of the diameter of the disc, an information piece representative of the recording type (an information piece representative of whether or not the disc is of the phase change type), and an information piece representative of whether the disc is recordable or rewritable. The part “B” of a field ID3 or ID4 stores an information piece representative of a field ID value, and an information piece representative of an identification number (an ID number) of the maker or manufacturer of the disc.

[0061] FIG. 5 shows the details of a field ID2 which is listed in FIG. 2 or FIG. 3 . In the field ID2, the frames having numbers of “6”-“15” are assigned to the part “B”. As shown in FIG. 5 , the frame having a number of “6” stores an information piece representative of a field ID value. The frames having numbers of “7” and “8” store an OPC recommended code. The frames having numbers of “9”, “10”, “11”, and “12” store a write strategy code “1”. The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of at least one of the information pieces in the part “B”. The parity may be omitted. In this case, the frames having numbers of “13”, “14”, and “15” are set as reserved ones. The OPC recommended code indicates a recording power level Po and an erasing power level Pe recommended by the disc maker (the disc manufacturer). The OPC recommended code may further indicate a recommended bias power level Pb. The OPC recommended code may indicate the ratio ε=Pe/Po, that is, the ratio of the recommended erasing power level Pe to the recommended recording power level Po. The OPC recommended code may further indicate record optimizing information including a recommended asymmetry value or a value β representative of the position of a short mark portion relative to a long mark portion of an 8-16 modulation-resultant signal reproduced from the disc to decide recording conditions. The write strategy code “1” has time information pieces representative of recommended pulse widths Ttop, Tmp, and Tc1 in the strategy of FIG. 1 .

[0062] FIG. 6 shows the details of a field ID5 which is listed in FIG. 2 or FIG. 3 . In the field IDS, the frames having numbers of “6”-“15” are assigned to the part “B”. As shown in FIG. 6 , the frame having a number of “6” stores an information piece representative of a field ID value. The frames having numbers of “7”, “8”, “9”, and “10” store a write strategy code “2”. The frames having numbers of “11” and “12” store an information piece representative of a desired disc scanning velocity value (1X). The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of at least one of the information pieces in the part “B”. The parity may be omitted. In this case, the frames having numbers of “13”, “14”, and “15” are set as reserved ones. The write strategy code “2” has time information pieces representative of recommended pulse widths Ttop, Tmp, and Tc1 in a strategy using a predetermined recording waveform different from that in FIG. 1 . In general, the desired disc scanning velocity value (1X) indicates what times the normal linear velocity the disc can be scanned at. The desired disc scanning velocity value (1X) is equal to the normal linear velocity relating to the scanning of the disc. When the normal linear velocity is equal to 3.49 m/s, the desired disc scanning velocity value (1X) is a numerical value of “3.49”. Alternatively, the desired disc scanning velocity value (1X) may be “1” which is a multiplier for the normal linear velocity. The desired disc scanning velocity value (1X) may be a hexadecimal coded value of “1” (a multiplier) or “3.49”.

[0063] Preferably, frames in each of the present field (ID5) and later fields which are assigned to desired disc scanning velocity values further store record optimizing information including a recommended asymmetry value or a value β representative of the position of a short mark portion relative to a long mark portion of an 8-16 modulation-resultant signal reproduced from the disc to decide recording conditions. The record optimizing information may also be in an OPC recommended code.

[0064] As the total number of different linear velocities from which the scanning velocity of an optical disc can be selected increases, the total number of the fields ID2 and ID5 and similar fields increases. The recorded contents of the fields ID2 and ID5 correspond to the normal linear velocity relating to the scanning of the disc. In the case of an optical disc designed to be scanned at only the normal linear velocity, an information piece representative of a desired disc scanning velocity value (1X) may be absent from the field ID5.

[0065] As previously mentioned, the fields ID0, ID1, ID2, ID3, ID4, and ID5 in FIG. 3 are similar to those in FIG. 2 . The recorded contents of the fields ID2 and ID5 in FIG. 3 correspond to the normal linear velocity relating to the scanning of the disc.

[0066] FIG. 7 shows the details of a field IDn which is listed in FIG. 3 . When “n” is equal to “6”, the field IDn in FIG. 7 is a field ID6. In the field ID6, the frames having numbers of “6”-“15” are assigned to the part “B”. As shown in FIG. 7 , the frame having a number of “6” stores an information piece representative of a field ID value. The frames having numbers of “7” and “8” store an OPC recommended code for the 2-fold linear velocity relating to the scanning of the disc. The frames having numbers of “9”, “10”, “11”, and “12” store a write strategy code “1” for the 2-fold linear velocity relating to the scanning of the disc. The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of at least one of the information pieces in the part “B”. The parity may be omitted. In this case, the frames having numbers of “13”, “14”, and “15” are set as reserved ones. The OPC recommended code indicates a recording power level Po and an erasing power level Pe recommended by the disc maker for the 2-fold linear velocity relating to the scanning of the disc. The OPC recommended code may also indicate a recommended bias power level Pb for the 2-fold linear velocity relating to the scanning of the disc. The OPC recommended code may further indicate record optimizing information including a recommended asymmetry value or a value β representative of the position of a short mark portion relative to a long mark portion of an 8-16 modulation-resultant signal reproduced from the disc to decide recording conditions for the 2-fold linear velocity relating to the scanning of the disc. The write strategy code “1” has time information pieces representative of recommended pulse widths Ttop, Tmp, and Tc1 in the strategy of FIG. 1 for the 2-fold linear velocity relating to the scanning of the disc.

[0067] FIG. 8 shows the details of a field IDn+1 which is listed in FIG. 3 . When “n+1” is equal to “7”, the field IDn+1 in FIG. 8 is a field ID7. In the field ID7, the frames having numbers of “6”-“15” are assigned to the part “B”. As shown in FIG. 8 , the frame having a number of “6” stores an information piece representative of a field ID value. The frames having numbers of “7”, “8”, “9”, and “10” store a write strategy code “2”for the 2-fold linear velocity relating to the scanning of the disc. The frames having numbers of “11” and “12” store an information piece representative of a desired disc scanning velocity value (2X) equal to the 2-fold linear velocity, that is, equal to twice the normal linear velocity relating to the scanning of the disc. The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of at least one of the information pieces in the part “B”. The parity may be omitted. In this case, the frames having numbers of “13”, “14”, and “15” are set as reserved ones. The write strategy code “2” has time information pieces representative of recommended pulse widths Ttop, Tmp, and Tc1 in a strategy using a predetermined recording waveform different from that in FIG. 1 for the 2-fold linear velocity relating to the scanning of the disc.

[0068] With reference back to FIG. 7 , in the field IDn, the frames having numbers of “6”-“15” are assigned to the part “B”. As shown in FIG. 7 , the frame having a number of “6” stores an information piece representative of a field ID value. The frames having numbers of “7” and “8” store an OPC recommended code for the m-fold linear velocity relating to the scanning of the disc. The frames having numbers of “9”, “10”, “11”, and “12” store a write strategy code “1” for the m-fold linear velocity relating to the scanning of the disc. The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of at least one of the information pieces in the part “B”. The parity may be omitted. In this case, the frames having numbers of “13”, “14”, and “15” are set as reserved ones. The OPC recommended code indicates a recording power level Po and an erasing power level Pe recommended by the disc maker for the m-fold linear velocity relating to the scanning of the disc. The OPC recommended code may also indicate a recommended bias power level Pb for the m-fold linear velocity relating to the scanning of the disc. The OPC recommended code may further indicate record optimizing information including a recommended asymmetry value or a value β representative of the position of a short mark portion relative to a long mark portion of an 8-16 modulation-resultant signal reproduced from the disc to decide recording conditions for the m-fold linear velocity relating to the scanning of the disc. The write strategy code “1” has time information pieces representative of recommended pulse widths Ttop, Tmp, and Tc1 in the strategy of FIG. 1 for the m-fold linear velocity relating to the scanning of the disc.

[0069] With reference to FIG. 8 , in the field IDn+1, the frames having numbers of “6”-“15” are assigned to the part “B”. As shown in FIG. 8 , the frame having a number of “6” stores an information piece representative of a field ID value. The frames having numbers of “7”, “8”, “9”, and “10” store a write strategy code “2” for the m-fold linear velocity relating to the scanning of the disc. The frames having numbers of “11” and “12” store an information piece representative of a desired disc scanning velocity value (mX) equal to the m-fold linear velocity, that is, equal to “m” times the normal linear velocity relating to the scanning of the disc. The frames having numbers of “13”, “14”, and “15” store an information piece representative of the parity of at least one of the information pieces in the part “B”. The parity may be omitted. In this case, the frames having numbers of “13”, “14”; and “15” are set as reserved ones. The write strategy code “2” has time information pieces representative of recommended pulse widths Ttop, Tmp, and Tc1 in a strategy using a predetermined recording waveform different from that in FIG. 1 for the m-fold linear velocity relating to the scanning of the disc.

[0070] In this way, as the total number of different linear velocities from which the scanning velocity of an optical disc can be selected increases by one, the total number of field types increases by two. For an optical disc designed to be scanned at a linear velocity selectable from the normal linear velocity and the 2-fold linear velocity, there are fields ID0 to ID7. For an optical disc designed to be scanned at a linear velocity selectable from the normal linear velocity, the 2-fold linear velocity, and the 4-fold linear velocity, there are fields ID0 to ID9. For an optical disc designed to be scanned at a linear velocity selectable from the normal linear velocity, the 2-fold linear velocity, the 4-fold linear velocity, . . . , and the m-fold linear velocity, there are fields ID0 to IDn+1. The total number of ID0 to IDn+1 indicates the total number of different linear velocities from which the scanning velocity of an optical disc can be selected.

[0071] Preferably, an application code in the field ID1 includes an extension code representing the total number of different linear velocities from which the scanning velocity of an optical disc can be selected. For an optical disc storing only fields ID0 to ID5, the extension code is set to “0” which represents that the disc can be scanned at only the normal linear velocity. For an optical disc storing only fields ID0 to ID7, the extension code is set to “2” which represents that the disc can be scanned at a linear velocity selectable from the normal linear velocity and the 2-fold linear velocity. Thus, the extension code is set to a value equal to the maximum number following “ID” minus “5”. For example, the extension code is set to “n−4” when the maximum number following “ID” is equal to “n+1”.

[0072] As previously mentioned, the total number of field types denoted by ID0, ID1, ID2, . . . increases in accordance with the total number of different linear velocities from which the scanning velocity of an optical disc can be selected. This design enables a recording and reproducing apparatus to get optimal recording conditions, that is, optimal values about the setting of laser power, for each of the different linear velocities relating to the scanning of the disc.

[0073] With reference to FIG. 9 , an optical disc (for example, a DVD−RW) includes a lead-in area and a data area. The lead-in area extends in an inner portion of the disc. The data area extends outward of the lead-in area. The lead-in area and the data area form an information management area and an information recording area, respectively. Information for managing the recording and reproduction of data on and from the data area, and also information peculiar to the disc are recorded on the lead-in area. Data (for example, contents data or user data) can be recorded on and reproduced from the data area. In an optical disc which has not yet been subjected to the data recording, LPPs (land pre-pits) representative of an address signal and a management signal, and a wobbling portion representative of a wobble signal are formed along a groove on a 1-ECC-block by 1-ECC-block basis.

[0074] The lead-in area of a DVD−RW includes a readable emboss area exclusively for playback. The readable emboss area is formed with emboss pre-pits, and has only wobbling information. LPP information is absent from the readable emboss area. In a DVD−R, a readable emboss area may be replaced with a recordable and readable area. In this case, LPP information exists on the recordable and readable area as LPP information exists on other portions of the lead-in area.

[0075] FIG. 10 shows a portion of an optical disc 101 such as a DVD−RW or a DVD−R. The optical disc 101 includes an information recording layer 105 having a phase change film or a pigment film. The optical disc 101 includes a metal-deposited layer (for example, a gold-deposited layer) 106 which extends below the information recording layer 105 as viewed in FIG. 10 . The metal-deposited layer 106 acts to reflect a light beam (a laser beam) 108 .

[0076] The optical disc 101 has an information recording area formed with a spiral of a wobbling groove 102 and a spiral of a land 103 . It should be noted that FIG. 10 illustrates the groove 102 and the land 103 in an opposite manner. Specifically, FIG. 10 illustrates the groove 102 and the land 103 as those in a stamper for an optical disc. A portion of the land 103 is located between neighboring portions of the groove 102 . A groove portion and a pair of land portions adjoining the groove portion compose a track portion. The groove 102 and the land 103 are coated with a protective film 107 . For an easier understanding, groove portions, land portions, and track portions which neighbor in a radial direction of the optical disc 101 are also referred to as grooves, lands, and tracks, respectively.

[0077] Alternatively, the optical disc 101 may have a set of concentric circular wobbling grooves 102 and lands 103 formed between neighboring grooves 102 .

[0078] Main information can be recorded on and reproduced from the groove (or the grooves) 102 . First auxiliary information is previously recorded on the optical disc 101 as the wobble of the groove (or the grooves) 102 . Second auxiliary information (pre-pit signals or land pre-pit signals) is previously recorded on the land (or the lands) 103 . Specifically, the second auxiliary information is represented by land pre-pits (LPPs) 104 , that is, pre-pits 104 formed in the land (or the lands) 103 . The first auxiliary information and the second auxiliary information are used for the recording of main information on the optical disc 101 or the reproduction of main information therefrom.

[0079] The first auxiliary information contains a reference clock signal which is used for the control of rotation of the optical disc 101 . The second auxiliary information contains address information (LPP address information) from which the position of an arbitrary point on the optical disc 101 can be detected. The second auxiliary information also contains management information for the signal recording on the optical disc 101 .

[0080] During the recording of main information on the optical disc 101 or the reproduction of main information therefrom, the track is scanned by the light beam 108 while the optical disc 101 is rotated. In this case, the wobble of the groove (or the grooves) 102 and the pre-pits 104 in the land (or the lands) 103 are detected. A wobble signal is generated in response to the detection of the wobble of the groove (or the grooves) 102 . The reference clock signal is reproduced from the wobble signal. Rotation of the optical disc 101 is controlled in response to the reproduced reference clock signal. LPP signals, that is, land pre-pit signals, are generated in response to the detection of the pre-pits 104 . The position of a currently-accessed point on the optical disc 101 is detected from the LPP signals. Management information for the signal recording on the optical disc 101 can be derived from the LPP signals.

[0081] The light beam 108 is focused into a light spot SP on the optical disc 101 . A tracking process forces the center of the light spot SP to move along a substantial central line of the groove 102 during the rotation of the optical disc 101 . The light spot SP extends over the groove 102 of interest and also the lands 103 adjoining the groove 102 of the interest. The light beam 108 is reflected by the optical disc 101 , traveling back as a reflected light beam. The reflected light beam is sensed by a photodetector. The photodetector has segments separated by a line parallel to the direction of rotation of the optical disc 101 . According to a radial push-pull method using the photodetector, the second auxiliary information represented by the pre-pits 104 is reproduced from portions of the reflected light beam which correspond to the light-spot portions extending over the lands 103 . At the same time, the first auxiliary information represented by the wobble of the groove 102 is reproduced from a portion of the reflected light beam which corresponds to the light-spot portion extending over the groove 102 . The reference clock signal is detected from the first auxiliary information. The reference clock signal is used for the control of rotation of the optical disc 101 .

[0082] FIG. 11 shows the arrangement of fields ID0, ID1, ID2, . . . , and IDn+1 in the lead-in area and the data area of an optical disc (for example, a DVD−RW). As shown in FIG. 11, a set of fields ID1, ID2, . . . , and IDn+1 is recurrently placed in specified portions of the lead-in area between a lead-in start position and a lead-in end position (a lead-in start ECC block address “FFDD05h” and a lead-in end ECC block address “FFD000h”). Specifically, a set of fields ID1, ID2, . . . , and IDn+1 is recurrently placed in a first lead-in area portion between the lead-in start position and a position immediately preceding a readable emboss start position, and a second lead-in area portion between a position immediately following a readable emboss end position and the lead-in end position.

[0083] With reference to FIG. 11 , fields ID0 are placed in the data area which starts from a data start position immediately following the lead-in end position and having an ECC block address “FFCFFFh”. As previously mentioned, each field ID0 duplicately stores an information piece representative of the address of a corresponding ECC block.

[0084] For an optical disc designed to be scanned at only the normal linear velocity, a set of fields ID1, ID2, . . . , and ID5 is recurrently placed in the lead-in area. As the total number of different linear velocities from which the scanning velocity of an optical disc can be selected increases, the total number of fields ID1, ID2, . . . placed in the lead-in area increases. Therefore, as the total number of different linear velocities from which the scanning velocity of an optical disc can be selected increases, the number of the recurrence of a set of fields ID1, ID2, . . . placed in the lead-in area decreases. All fields ID1, ID2, . . . corresponding to different linear velocities from which the scanning velocity of an optical disc can be selected are placed in the lead-in area. Accordingly, the lead-in area can be used without waste. Furthermore, at each of the different linear velocities relating to the scanning of the disc, corresponding fields ID1, ID2, can be quickly accessed.

[0085] As shown in FIG. 11, a field ID1 is placed at the lead-in start position, and fields ID2, ID3, . . . are successively placed at positions following the lead-in start position. A set of fields ID1, ID2, . . . , and IDn+1 is recurrently placed in the lead-in area. In the case where a portion of the lead-in area between the position of a last field (a provisional last field) IDn+1 and the lead-in end position is insufficient to store a complete set of fields ID1, ID2, . . . , and IDn+1, that potion of the lead-in area is loaded with fields ID0. As previously mentioned, each field ID0 duplicately stores an information piece representative of the address of a corresponding ECC block.

[0086] In some cases, the recording and reproduction of a signal on and from the data area of an optical disc are on a real-time basis. To reliably implement the signal recording and the signal reproduction, it is desirable to surely read addresses represented by LPPs on the disc. For this reason, the data area is loaded with fields ID0, each of which duplicately has an information piece of a corresponding LPP address (a corresponding ECC block address). Regarding the start of the recording of a signal on the data area, it is desirable to surely read the addresses of several ECC blocks in a portion of the lead-in area which extends adjacently inward of the lead-in end position. As previously mentioned, in the case where a portion of the lead-in area between the position of a last field (a provisional last field) IDn+1 and the lead-in end position is insufficient to store a complete set of fields ID1, ID2, . . . , and IDn+1, that potion of the lead-in area is loaded with fields ID0. This design makes it possible to surely read the addresses of several ECC blocks in a portion of the lead-in area which extends adjacently inward of the lead-in end position since each field ID0 duplicately has an information piece of a corresponding LPP address (a corresponding ECC block address).

[0087] The lead-in area of a DVD−RW includes a readable emboss area from which LPP information is absent. Fields ID1, ID2, . . . , and IDn+1 are also absent from the readable emboss area. In the case where a portion of the lead-in area between the position of a last field (a provisional last field) IDn+1 and the readable emboss start position is insufficient to store a complete set of fields ID1, ID2, . . . , and IDn+1, that potion of the lead-in area is preferably loaded with fields ID0. According to this design, it is possible to surely confirm or detect the readable emboss start position. Preferably, a portion of the lead-in area which extends adjacently outward of the readable emboss end position, and which has a size corresponding to several tracks or several ECC blocks is loaded with fields ID0. This design makes it possible to surely confirm or detect the readable emboss end position.

[0088] A DVD−R having a lead-in area with a readable emboss area is similar to the DVD−RW in arrangement of fields ID0, ID1, ID2, . . . , and IDn+1 . In a DVD−R including an LPP-added pre-recorded area instead of a readable emboss area, a set of fields ID1, ID2, . . . , and IDn+1 is recurrently placed over the whole of the lead-in area containing the LPP-added pre-recorded area.

[0089] FIG. 12 shows an information-signal recording and reproducing apparatus which operates on an optical disc 22 such as a DVD−RW or a DVD−R. The apparatus of FIG. 12 records and reproduces information (a signal) on and from the optical disc 22 while scanning the optical disc 22 by a laser beam at a constant linear velocity selectable from the normal linear velocity and at least one higher linear velocity equal to an integer multiple of the normal linear velocity. The apparatus of FIG. 12 includes a key input unit 10 , a system controller 12 , a signal processor 14 , a servo processor 16 , a driver 18 , a spindle motor 20 , an optical head (optical pickup) 24 , an amplifier unit 26 , a memory 28 , an audio-video encoding and decoding unit 30 , a memory 32 , an input/output terminal 34 , and a temperature sensor 36 .

[0090] The temperature sensor 36 is located near the optical disc 22 placed in position within the apparatus. The temperature sensor 36 detects an ambient temperature of the optical disc 22 . The temperature sensor 36 is connected to the amplifier unit 26 .

[0091] The spindle motor 20 acts to rotate the optical disc 22 . While the spindle motor 20 rotates the optical disc 22 , the optical head 24 writes and reads information (a signal) thereon and therefrom. The spindle motor 20 is driven and controlled by the driver 18 . The spindle motor 20 is provided with an FG generator and a rotational position sensor (an angular position sensor). The rotational position sensor includes, for example, a Hall element. The FG generator outputs an FG signal (a rotational speed signal). The Hall element outputs a rotational position signal. The FG signal and the rotational position signal are fed back to the driver 18 .

[0092] The optical head 24 faces the optical disc 22 placed in position within the apparatus. A feed motor (not shown) moves the optical head 24 radially with respect to the optical disc 22 . The feed motor is driven by the driver 18 . The optical head 24 includes a semiconductor laser, a collimator lens, and an objective lens. The semiconductor laser acts as a source for emitting a light beam (a laser beam). The emitted laser beam is focused into a laser spot on the optical disc 22 by the collimator lens and the objective lens. The optical head 24 includes a 2-axis actuator for moving the objective lens to implement focusing and tracking of the laser spot with respect to a track on the optical disc 22 . The semiconductor laser is driven by a laser drive circuit in the amplifier unit 26 . The 2-axis actuator is driven by the driver 18 .

[0093] The key input unit 10 includes a plurality of keys which can be operated by a user. The key input unit 10 generates command signals in accordance with its operation by the user. The command signals are transmitted from the key input unit 10 to the system controller 12 . The command signals include a command signal for starting a recording mode of operation of the apparatus, and a command signal for starting a playback mode of operation of the apparatus. The key input unit 10 generates control data in accordance with its operation by the user. The control data are sent from the key input unit 10 to the system controller 12 .

[0094] The system controller 12 includes, for example, a microcomputer or a similar device which operates in accordance with a control program stored in its internal memory. The control program is designed to enable the system controller 12 to implement operation steps mentioned later. The system controller 12 controls the signal processor 14 , the servo processor 16 , the amplifier unit 26 , and the audio-video encoding and decoding unit 30 in response to the command signals fed from the key input unit 10 .

[0095] Control data can be fed to the system controller 12 via an input terminal (not shown). The control data fed to the system controller 12 via the input terminal, and the control data fed to the system controller 12 from the key input unit 10 include a signal for adjusting the resolution of pictures represented by contents information to be recorded, a signal for separating quickly-moving scenes such as car racing scenes represented by contents information, and a signal for giving priority to a recording time. The system controller 12 changes an actual recording time in accordance with the control data. The system controller 12 enables the setting of the actual recording time to be selected by the user.

[0096] When the apparatus is required to start operating in the playback mode, the key input unit 10 is actuated to generate the playback start command signal. The playback start command signal is sent from the key input unit 10 to the system controller 12 . The system controller 12 controls the servo processor 16 and the amplifier unit 26 in response to the playback start command signal, thereby starting the playback mode of operation of the apparatus. The control of the servo processor 16 includes steps of controlling the driver 18 . Firstly, the system controller 12 starts rotation of the optical disc 22 and application of a laser spot thereon through the control of the driver 18 . The optical head 24 is controlled by the driver 18 , thereby reading out address information (LPP address information) from the optical disc 22 . The readout address information is transmitted from the optical head 24 to the system controller 12 via the amplifier unit 26 . The system controller 12 finds or decides a target sector (a target track portion) to be played back by referring to the address information. The system controller 12 controls the optical head 24 via the servo processor 16 , the driver 18 , and the feed motor, thereby moving the optical head 24 radially with respect to the optical disc 22 and hence moving the laser spot to the target sector on the optical disc 22 . When the movement of the laser spot to the target sector is completed, the system controller 12 operates to start the reproduction of a signal from the target sector on the optical disc 22 . In this way, the playback mode of operation of the apparatus is started. During the playback mode of operation of the apparatus, the target sector is repetitively changed from one to another.

[0097] During the playback mode of operation of the apparatus, the optical head 24 scans the optical disc 22 and generates a reproduced RF signal containing information read out therefrom. The optical head 24 outputs the RF signal to the amplifier unit 26 . The amplifier unit 26 enlarges the RF signal from the optical head 24 . The amplifier unit 26 generates a main reproduced signal from the enlarged RF signal. In addition, the amplifier unit 26 generates a servo error signal (tracking and focusing servo error signals) from the output signal of the optical head 24 . The amplifier unit 26 includes an equalizer for optimizing the frequency aspect of the main reproduced signal. Also, the amplifier unit 26 includes a PLL (phase locked loop) circuit for extracting a bit clock signal from the equalized main reproduced signal, and for generating a speed servo signal from the equalized main reproduced signal. Furthermore, the amplifier unit 26 includes a jitter generator for comparing the time bases of the bit clock signal and the equalized main reproduced signal, and for detecting jitter components from the results of the time-base comparison. A signal of the detected jitter components is sent from the amplifier unit 26 to the system controller 12 . The tracking and focusing servo signals and the speed servo signal are sent from the amplifier unit 26 to the servo processor 16 . The equalized main reproduced signal is transmitted from the amplifier unit 26 to the signal processor 14 .

[0098] The servo processor 16 receives the speed servo signal and the tracking and focusing servo signals from the amplifier unit 26 . The servo processor 16 receives the rotation servo signals from the spindle motor 20 via the driver 18 . In response to these servo signals, the servo processor 16 implements corresponding servo control procedures.

[0099] Specifically, the servo processor 16 generates a rotation control signal on the basis of the speed servo signal and the rotation servo signals. The rotation control signal is sent from the servo processor 16 to the spindle motor 20 via the driver 18 . The spindle motor 20 rotates at a speed depending on the rotation control signal. The rotation control signal is designed to rotate the optical disc 22 at a speed corresponding to a selected constant linear velocity or a given constant linear velocity relating to the scanning of the optical disc 22 .

[0100] In addition, the servo processor 16 generates servo control signals on the basis of the focusing and tracking servo signals. The servo control signals are sent from the servo processor 16 to the 2-axis actuator in the optical head 22 via the driver 18 . The 2-axis actuator controls the laser spot on the optical disc 22 in response to the servo control signals, and thereby implements focusing and tracking of the laser spot with respect to a track on the optical disc 22 .

[0101] During the playback mode of operation of the apparatus, the signal processor 14 receives the main reproduced signal from the amplifier unit 26 . The signal processor 14 is controlled by the system controller 12 , thereby converting the main reproduced signal into a corresponding reproduced digital signal. The signal processor 14 detects a sync signal from the reproduced digital signal. The signal processor 14 decodes an 8-16 modulation-resultant signal of the reproduced digital signal into NRZ data, that is, non-return-to-zero data. The signal processor 14 subjects the NRZ data to error correction for every correction block (every ECC block), thereby generating a sector address signal and first and second information signals. The sector address signal represents the address of a currently-accessed sector on the optical disc 22 . The sync signal and the sector address signal are fed from the signal processor 14 to the system controller 12 .

[0102] During the playback mode of operation of the apparatus, the signal processor 14 temporarily stores the first and second information signals in the memory 28 . Thus, the signal processor 14 writes the first and second information signals into the memory 28 , and reads the first and second information signals therefrom. Writing and reading the first and second information signals into and from the memory 28 are controlled to absorb a time-domain change in the transfer rates of the first and second information signals. The memory 28 includes, for example, a D-RAM having a capacity of 4 Mbytes or 64 Mbytes. The signal processor 14 outputs the readout signal (the first and second information signals read out from the memory 28 ) to the audio-video encoding and decoding unit 30 .

[0103] In the case where the first and second information signals fed from the memory 28 via the signal processor 14 are compressed data (for example, MPEG2 data) in which audio data and video data are multiplexed, the audio-video encoding and decoding unit 30 separates the first and second information signals into compressed audio data and compressed video data. The audio-video encoding and decoding unit 30 expands and decodes the compressed audio data into non-compressed audio data. In addition, the audio-vide encoding and decoding unit 30 expands and decodes the compressed video data into non-compressed video data. During the expansively decoding process, the audio-video encoding and decoding unit 30 temporarily stores signals and data in the memory 32 . The memory 32 includes, for example, a D-RAM having a capacity of 4 Mbytes or 64 Mbytes. The audio-video encoding and decoding unit 30 converts the non-compressed audio data into a corresponding analog audio signal through digital-to-analog conversion. Also, the audio-video encoding and decoding unit 30 converts the non-compressed video data into a corresponding analog video signal through digital-to-analog conversion. The audio-video encoding and decoding unit 30 applies the analog audio signal and the analog video signal to the input/output terminal 34 . The analog audio signal and the analog video signal are transmitted to an external via the input/output terminal 34 .

[0104] When the apparatus is required to start operating in the recording mode, the key input unit 10 is actuated to generate the recording start command signal. The recording start command signal is transmitted from the key input unit 10 to the system controller 12 . The system controller 12 controls the servo processor 16 and the amplifier unit 26 in response to the recording start command signal, thereby starting the recording mode of operation of the apparatus. The control of the servo processor 16 includes steps of controlling the driver 18 . Firstly, the system controller 12 starts rotation of the optical disc 22 and application of a laser spot thereon through the control of the driver 18 . The optical head 24 is controlled by the driver 18 , thereby reading out address information (LPP address information) from the optical disc 22 . The readout address information is sent from the optical head 24 to the system controller 12 via the amplifier unit 26 . The system controller 12 finds or decides a target sector (a target track portion), on which a signal is to be recorded, by referring to the address information. The system controller 12 controls the optical head 24 via the servo processor 16 and the driver 18 , thereby moving the laser spot to the target sector on the optical disc 22 . During the recording mode of operation of the apparatus, the target sector is repetitively changed from one to another.

[0105] During the recording mode of operation of the apparatus, an audio signal and a video signal to be recorded are fed via the input/output terminal 34 to the audio-video encoding and decoding unit 30 . The audio-video encoding and decoding unit 30 converts the audio signal into corresponding audio data through analog-to-digital conversion. In addition, the audio-video encoding and decoding unit 30 converts the video signal into corresponding video data through analog-to-digital conversion. The audio-video encoding and decoding unit 30 compressively encodes the audio data and the video data into compressed audio data and compressed video data (for example, MPEG2 audio data and MPEG2 video data). The audio-video encoding and decoding unit 30 multiplexes the compressed audio data and the compressed video data to form multiplexed contents data. The audio-vide encoding and decoding unit 30 outputs the multiplexed contents data to the signal processor 14 . During the compressively encoding process, the audio-video encoding and decoding unit 30 temporarily stores data in the memory 32 .

[0106] During the recording mode of operation of the apparatus, the signal processor 14 adds error correction code signals (ECC signals or PI and PO signals) to the multiplexed contents data. The signal processor 12 subjects the ECC-added data to NRZ and 8-16 modulation encoding procedures. The signal processor 14 adds a sync signal to the encoding-resultant contents data to form sync-added contents data. The sync signal is fed from the system controller 12 . The sync-added contents data are temporarily stored in the memory 28 . The sync-added contents data are read out from the memory 28 at a data rate corresponding to a data rate of the signal recording on the optical disc 22 . The signal processor 14 subjects the readout contents data to given modulation for record. The signal processor 14 outputs the modulation-resultant signal to the amplifier unit 26 . The output signal of the signal processor 14 is an 8-16 modulation-resultant signal. The amplifier unit 26 corrects the waveform of the output signal of the signal processor 14 . The amplifier unit 26 generates a laser drive signal in response to the waveform-correction-resultant signal. The amplifier unit 26 outputs the laser drive signal to the optical head 24 . The optical head 24 records the output signal of the amplifier unit 26 on the target sector (the target track portion) on the optical disc 22 .

[0107] As shown in FIG. 13 , the amplifier unit 26 includes a servo error signal generation circuit 49 , an RF amplifier 50 , an equalizer 52 , a PLL circuit 54 , a jitter signal generation circuit 56 , a laser drive circuit 58 , a waveform correction circuit 60 , a switch 62 , a test pattern generation circuit 64 , a temperature detection circuit 66 , an asymmetry detection circuit 70 , a PLL circuit 71 , a wobble detection circuit 72 , an address detection circuit 73 , and a timing signal generation circuit 74 .

[0108] The temperature detection circuit 66 in the amplifier unit 26 is connected to the temperature sensor 36 and the system controller 12 (see FIG. 12 ). The temperature detection circuit 66 is an interface between the temperature sensor 36 and the system controller 12 . A signal representative of the ambient temperature of the optical disc 22 is transmitted from the temperature sensor 36 to the system controller 12 via the temperature detection circuit 66 .

[0109] The amplifier unit 26 operates as follows. The servo error signal generation circuit 49 and the RF amplifier 50 in the amplifier unit 26 receive the output signal of the optical head 24 . The servo error signal generation circuit 49 produces a servo error signal from the output signal of the optical head 24 . The servo error signal generation circuit 49 outputs the servo error signal to the servo processor 16 . During the playback mode of operation of the apparatus, the RF amplifier 50 enlarges the output signal o