JP3175978B2 - Tracking error signal generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk and a tracking error signal generating device, and more particularly to an optical disk of high density recording using a sampled servo method and a tracking for generating a tracking error signal from the optical disk. The present invention relates to an error signal generation device.

[0002]

2. Description of the Related Art As a recording format of a conventional optical disk, a recording format of a sampled servo system is known.

FIG. 12 shows a recording format of a sampled servo type optical disk. The optical disk of the sampled servo system does not have a pre-group (guide groove) on the recording film of the optical disk, and has 137 of one track.
Servo areas (fields) are preformatted in six places. The sampled servo type optical disc uses this pre-format to prevent tracking error and recording / recording.
It is characterized in that a clock for reproduction and the like can be generated by sampling.

[0004] In the program area PA of the optical disk DK, as shown in FIG. 12, a spiral (spiral) signal track extending from the inner peripheral side to the outer peripheral side of the optical disk DK is formed. One track is divided into 32 sectors. Each sector consists of 43 segments, and each segment consists of 18 bytes. In the first segment # 0 of one sector, a sector synchronization signal S _sync (2 bits) for synchronizing in sector units and a sector address S _ADR for indicating the address of the sector are provided.
(16 bits) is preformatted. Preformatting is performed in the process of mastering the optical disc DK. Each of the segments # 1 to # 42 is
2-byte servo region F _S and 16-byte data area F
_D and a total area of 18 bytes.

[0005] FIG. 13 shows a recording format of the servo area F _S. The 2-byte servo area F _S is divided into two servo bytes # 1 and # 2 one by one. The first wobble pit P _W1 is pre-formatted in the third bit and the second wobble pit P _W2 is pre-formatted in the eighth bit of the servo byte # 1. As shown in FIG. 13, the position of the first wobble pit P _W1 is the third bit like P _{W1 A in} the case of 16 tracks (A), but is 16 bits.
When the track (B) is _reached , the bit shifts to the fourth bit as in _PW1B . By switching the position of the first wobble pit P _W1 every 16 tracks in this manner, the number of crossing tracks during the search can be accurately detected.

[0006] The first wobble pit P _W1 and the second wobble pit P _W2 are displaced by １ ／ of the track pitch in the trace direction left and right (in the radial direction of the write-once optical disc DK) with respect to the track center TC. The tracking error is detected based on the difference between the amount of return light at the first wobble pit P _W1 and the amount of return light at the second wobble pit P _W2 . The clock pit CP for synchronization is preformatted in the 12th bit of the servo byte # 2. Second wobble pit P _W2 and clock pit C
P is a mirror surface having an interval of 19 channel clock lengths, during which the 19 channel clocks are counted to synchronize each segment, and a focus error is detected during this synchronization detection period. Detection is also performed. More servo area F _S tracking signals read by the laser beam S _T1 (S _{T1 A} or S _T1B), shows a sector synchronization signal S _sync in Figure 13 below.

Next, a method of detecting a tracking error by wobble pits will be described with reference to FIG. A is
In the case where the central axes of the pair of wobble pits P _W1 and P _W2 on (track center axis) read beam has passed, the RF signal in this case is shown as S _A. When passing through the vicinity of the pit, the amount of reflected light becomes small and dark due to the diffraction effect of light, and becomes darkest when passing just above the clock pit CP as shown in the figure. B is a case where the read beam has passed the inner peripheral side of the track center axis, and the RF signal at that time is S _B
As shown. In this case, to pass just above the wobble pits P _W1, dark portion due to the wobble pits P _W1 still darker than the dark portion due to the wobble pits P _W2. C
Is a case where the read beam has passed through the outer peripheral side of the track center axis, RF signal in this case is shown as S _C,
In this case shows the S _B opposite waveform.

Here, a signal value obtained by performing signal sampling at the time of the wobble pit P _W1 is represented by SAMPLE.
(T ₁ ), and a signal value obtained by performing signal sampling at the time of the wobble pit P _W2 is SAMPLE (T ₂ )
SAMPLE (T ₁ ) −SAMPLE
If (T ₂ ) is taken, it becomes zero in the case of A, a negative value in the case of B, and a positive value in the case of C. Therefore, SAMPLE
If (T ₁ ) −SAMPLE (T ₂ ) = TE, TE
Can be used as a tracking error signal.

[0009]

SUMMARY OF THE INVENTION The above conventional sampler
According to the servo system, the wobble pit P for servo is used._W1, P
_W2And the clock pit CP are preformed on the optical disc.
(Pit pits), and from these pit trains
Obtain various information for servo such as a locking error signal
become.

When reading information, the laser light reflected at the signal pit PT is diffracted by the pit, and the amount of light returning to the optical pickup is reduced, and is regarded as a dark portion. Conversely, the intermediate portion between the signal pits PT is a mirror surface, and the entire laser light is reflected. Therefore, the amount of return light increases and the light pit is captured as a bright portion. In order to accurately read the servo information, it is necessary to read these light and dark portions without error. For this purpose, conventionally, as shown in FIG. 15A, the track pitch _TP is set to be smaller than the spot diameter B _L of the laser beam. It was necessary to make it large (about 1.6 μm).

In this case, in order to improve the recording density of the optical disc DK, FIG.
As shown in (c), the track pitch _TP is reduced by 1 /
Considering the case where the laser beam center is reduced to about 2 (0.8 μm), there are two cases: an on-track state where the center of the laser beam is on the center of the recording track axis, and an off-track state where the center of the laser beam is off the center of the recording track axis. In this case, there is a problem that the light amount difference becomes small and accurate servo cannot be performed, and there is a limit in reducing the track pitch width. In order to solve this problem, the applicant has proposed a method in which wobble pits are thinned out and recorded (Japanese Patent Application No. 03-64).
978). FIG. 16 shows the configuration of tracks and pits of a CAV optical disk used in the double-density recording method proposed by the applicant.

As shown in FIG. 16, the second k-th track is separated from the track center axis by L in the opposite direction,
A wobble pit P _W (2k-1) and a wobble pit P _W (2k) are provided in a so-called staggered manner, and a synchronous pit P _SYNC
And a track identification pits P _{DE T} provided on the track axis, and has a subsequent data area followed configuration and. The next (2k + 1) -th track has a configuration having wobble pits P _W (2k) and wobble pits P _W (2k + 1) in a zigzag shape opposite to the 2k-th track, and the synchronization pit P _SYNC is located on the track axis. The pits P _DET for track identification are provided but not provided.

In this case, for the second k-th track, the wobble pit P _W (2k−1) corresponds to the first wobble pit P _W1 and the wobble pit P _W (2k) corresponds to the second wobble pit P _W (2k).
It corresponds to wobble pit P _W2 , but the (2k + 1)
The wobble pit P _W (2k +
1) corresponds to the first wobble pit P _W1 , and the wobble pit P _W (2k) corresponds to the second wobble pit.

As described above, the 2k-th track and the (2
The (k + 1) th track and the wobble pit P
_W (2k) is shared. Therefore, this means that one of the staggered wobble pits is thinned out for each track, and as a result, the track pitch width T _P = 2L and the conventional example in which T _P = 4L (FIG. 15 ( a) The track pitch width T _P is 比 べ compared to that of a))
Is shortened. Accordingly, the number of tracks that can be recorded is doubled, and the recording density is doubled.

In this case, when a wobble pit is recorded as a preformat, rotation jitter or the like occurs in the recording apparatus, and for example, as shown in FIG. 17, the recording position of the wobble pit on the 2kth track and the (2k +
2) If the recording position of the wobble pit on the second track is not on the same radius line but is shifted (shift amount = Δx), a correct tracking error signal is generated when reproducing the (2k + 1) th track due to a shift in sampling timing. There are cases where they cannot be obtained.

In the case of the sampled servo system, since servo areas are adjacent between adjacent recording tracks, if a recording position of a wobble pit or a clock pit shifts, it is affected by the position shift and becomes unnecessary. Therefore, there is a problem in that a proper tracking error signal and a correct clock signal cannot be extracted due to excessive crosstalk.

Therefore, an object of the present invention is to provide a pit or clock for generating a tracking signal due to a rotation jitter of a recording apparatus at the time of recording when the track pitch is made smaller than the diameter of a reading laser beam spot for high density recording. It is an object of the present invention to provide an optical disc and a tracking error signal generation device capable of reducing the influence of a shift in the recording position of an extraction pit and generating a stable tracking error signal and clock signal.

[0018]

In order to solve the above-mentioned problems, the invention according to the first aspect of the present invention provides a recording track having a substantially concentric shape.
Data information is recorded in each of the recording tracks.
Information area for servo and servo for recording servo control information
Control information and optical data of the sampled servo system provided with
Disk, the segments constituting the recording track
M = (2n + 1) [m: natural number,
n: 0, 1, 2,...], and every m segments
In addition, the tracking error is applied to m consecutive segments.
-A pit for signal generation is provided to
All segments with or without a pit for signal generation
A pit for generating a tracking error signal is provided.
The servo control information of any one of all segments
Presence or absence of the tracking error signal generation pit in the area
A pit for discrimination is provided to indicate
In the servo control information area, a clock pin for clock extraction is used.
At least two readings using an optical disk with a slot
To generate a tracking error signal using the
A racking error signal generator, comprising:
The discriminating pin for the read beam on the track.
Compare the playback signal level corresponding to the recording position of the
Pits for tracking error signal generation
Signal of the reading beam scanning on the recording track
Discriminating means for discriminating the read beam,
Calculate the tracking error signal based on the playback signal,
Computing means for outputting.

Further, according to the second aspect of the present invention, a substantially concentric circle is provided.
A recording track is formed in the shape of
Data information area for recording data information and servo control information
Sampled control provided with servo control information for recording
In a disk-type optical disc, the recording track is structured.
M · (2n + 1) per segment
[M: natural number, n: 0, 1, 2,...]
In every other segment, the continuous m
A pit for generating a racking error signal is provided.
All segs with pits for king error signal generation
Or a pit for generating the tracking error signal
Is not provided for any one of the above segments
Generate the tracking error signal in the servo control information area
To indicate the presence or absence of pits for
Use an optical disc with clock pits
Tracking error using at least two reading beams
-A tracking error signal generator that generates signals
The read beam on an adjacent recording track.
Of the discrimination clock pit corresponding to the recording position of the discrimination clock pit.
The raw signal levels are compared and the tracking error signal
Scan over the recording track where the formation pit is formed
Determining means for determining the read signal of the read beam,
Based on the read signal of the read beam
Computing means for computing and outputting a signaling error signal.
It is characterized by the following.

[0020]

[0021]

[0022]

According to the first aspect of the present invention, the determining means includes:
Discrimination of read beams on adjacent recording tracks
The playback signal level corresponding to the recording position of the recording pit
And a pit for generating a tracking error signal is formed.
Of the reading beam scanning on the recording track
Determine the signal. The calculating means calculates the determined reading beam.
Calculate the tracking error signal based on the playback signal,
Output .

Therefore, tracking error signal generation
Radially adjacent to the segment provided with the pit
The segment has a pit for tracking error signal generation.
No optical disc with narrow track pitch
Tracking of adjacent segments when playing
There is no interference from error signal generation pits
Tracking error due to rotational jitter etc.
Is affected by the shift of the recording position of the error signal generation pit
To generate the correct tracking error signal without
Can be.

According to the second aspect of the present invention, the determination means
Indicates the read beam on the adjacent recording track.
Reproduction signal corresponding to the recording position of the discrimination clock pit
Compare levels and generate tracking error signal pits
For scanning scanning on the recording track where is formed
The reproduction signal of the beam is determined. The calculating means is configured to read the determined reading.
Tracking error signal based on the reproduction signal of the acquisition beam
Calculate and output the signal.

Therefore, the tracking error signal generation
Radially adjacent to the segment provided with the pit
The segment has a pit for tracking error signal generation.
Is not provided, and is provided with a discriminating clock pit.
Segment radially adjacent to the segment
There is no cockpit, so narrow track pitch
During playback of an optical disc
Pit for tracking error signal generation or discrimination clock
No interference from the cockpit, occurred during recording
A tracking error signal generation pin due to rotational jitter, etc.
Of recording position shift of clock and clock extraction pits
Correct tracking error signal without receiving
A clock signal can be generated.

[0026]

[0027]

[0028]

[0029]

[0030]

Next, a preferred embodiment of the present invention will be described with reference to the drawings. First Embodiment FIG. 1 shows a recording format of an optical disc according to a first embodiment. FIG. 1 shows only one segment of each recording track for simplification.

Recording tracks TR _{2n-1 to} TR _{2n + 4} (recording track numbers 2n- _{1 to 2n} +)
4, n: natural number) are each provided with a plurality of segments. Each segment corresponds to one data group, and the discrimination pit area ADP and the wobble pit area AW are sequentially viewed from the disk rotation direction side (upper side in the drawing).
P, a clock pit area ACP, and a data area ADT for recording various data are provided.

In the following description, the discrimination pit area ADP, the wobble pit area AWP and the clock pit area ACP are combined to form a servo area ASV. The determination pit area ADP, discrimination pits P _D indicating that the wobble pits will be described later is provided in the segment is provided. Specifically, in FIG. 1, the recording tracks TR _2n and TR ₂ having even-numbered recording track numbers are shown.
_{2n + 2,} TR _2n discrimination pits P _D to a segment on the ₊₄ is provided. In other words, the segment radially adjacent to the segment wobble pits is provided wobble pits and the judgment pits P _D is not provided.

In the wobble pit area AWP, wobble pits PW ₁ and PW ₂ used for generating a tracking error signal are provided on both sides of the recording track (between the recording tracks) in every other recording track.

In the clock pit area ACP, the recording tracks TR _{2n-1 to} TR _{2n + 4} are arranged in a line in the radial direction of the disk.
Is provided with a clock pit CP indicating a clock generation timing.

Here, the relationship between the reading beam irradiation positions will be described. The two read beams LB ₁ and LB ₂ are arranged at a distance d (distance between beam centers) in the circumferential direction of the optical disk so that they can be separated on a photodetector (not shown). As a result, a time delay of a delay time _Td expressed by the following equation occurs between the output signals of the two read beams.

T _d = d / V _C where V _C is the linear velocity of the read beam at the center of the read beam with respect to the optical disk.

As a result, the delay time _Td is corrected for the synchronization clock of the output signal of the photodetector (not shown) corresponding to the read beam LB ₂ , so that the optical detector (not shown) corresponding to the read beam LB ₁ It is necessary to obtain the output signal read timing. Therefore, by setting the integral multiple of the synchronizing clock period of the output signal of the light detector (not shown) corresponding to the beam LB ₂ reads the delay time T _d, a preferred becomes easy to correct the delay time T _d.

Next, the recording format of the entire optical disc will be described with reference to FIGS. In the present embodiment, the number of segments constituting a recording track is set to m · (2n + 1) [m: natural number, n: 0, 1, 2,.
..], Wobble pits as pits for generating a tracking error signal are provided in the m successive segments every m segments, and all segments having wobble pits or all wobble pits are not provided. A discrimination pit for indicating the presence or absence of a wobble pit is provided in one of the servo areas of the segment.

FIG. 2 shows the basic configuration of the recording format of the entire optical disc. FIG. 2 shows a case where m = 16 and n = 0, and a case where 16 segments are provided per round of the optical disc. In an actual optical disc, the number of segments is 1,000 or more per round.

In the case of the optical disk shown in FIG. 2, when viewed from the center point O of the optical disk in the radial direction, every other recording track, the servo area ASV _{1 of} each segment constituting one recording track (the area shown by hatching in the figure) the), wobble pits WP _1, WP ₂ shown in FIG. 1, determines pit P _D
And a clock pit CP, and only the clock pit CP is provided in the servo area ASV ₂ (shown by a white frame in the figure) of each segment constituting the other recording track.

FIG. 3 shows another example of the recording format of the entire optical disc. FIG. 3 shows a case where m = 4 and n = 1, and a case where 12 segments are provided for one round of the optical disk.

In the case of the optical disk shown in FIG. 3, when viewed in the radial direction from the center point O of the optical disk, every other recording track, the servo area ASV _{1 of} each segment constituting one recording track (the area indicated by hatching in the figure) the), wobble pits WP _1, WP ₂ shown in FIG. 1, determines pit P _D
And a clock pit CP, and only the clock pit CP is provided in the servo area ASV ₂ (shown by a white frame in the figure) of each segment constituting the other recording track.

FIG. 4 shows another example of the recording format of the entire optical disc. FIG. 4 shows that m = 1 and n = 7.
This is a special case of the optical disc, in which 15 segments are provided per round of the optical disc.

In the case of the optical disk shown in FIG. 4, when viewed from the center O of the optical disk in the radial direction, every other segment,
(In the figure, the region indicated by oblique lines) servo area ASV ₁ of one segment, the wobble pits WP _1, WP _2, discrimination pits P _D and the clock pit CP is provided, the servo region ASV ₂ (figure other segment In the middle and white frames, only the clock pit CP is provided.

[0045] In this case, the servo area of all segments, at least a clock pit CP is provided, also serves as a discrimination pits P _D of the servo area ASV ₁ as a clock pit CP, the servo region ASV ₂ is not be provided the clock pit CP, it is also possible to configure so as to extract a clock signal only in the servo area ASV _1. This eliminates interference due to the clock pits CP provided in the segments adjacent in the radial direction, stabilizes the extraction of the clock signal, and obtains an accurate clock signal. The detailed embodiment will be described later.

Next, the configuration of a main part of a reproducing apparatus for obtaining a tracking error signal using the optical disk of FIG. 1 will be described with reference to FIG. In this case, the reproducing apparatus reads the reading beam LB ₁ and the reading beam L which is the main beam.
It is assumed that signal reproduction is performed using three reading beams B ₂ (center beam) and one reading beam LB ₃ (not shown).

The reproducing apparatus 10 receives the first clock
Three reading beams LB based on the signal CLK1₁, LB_Two,
LB_ThreeReproduction signals A, B, and C (= RF signal)
Cancels the crosstalk from the playback signal S_PBAs
Output crosstalk canceller 11 and reproduction signal S_PB
To reproduce the reproduced data D_PBDecoder to output as
12 and a reading beam LB as a main beam_TwoReproduction message from
The first clock signal CLK1 based on the reproduced signal B
A first clock extracting circuit 13 for outputting the first clock signal;
Beam LB based on the signal CLK1_TwoRecords being read
Match the sampling timing of the pits for track identification
Applicable first sampling timing signal SMP1, read bee
Mu LB_TwoAt the wobble pit recording position of the reproduction signal B
Playback sample corresponding to the corresponding sampling timing
Ring timing signal B₁And playback sampling tie
Mining signal B_TwoTiming control circuit 14 that outputs
And playback based on the first sampling timing signal SMP1
The signal B is sampled and held, and the sampling signal B
_HLDA first sampling and holding circuit 15 that outputs
Read beam LB₁Based on the playback signal A, which is the playback signal from
A second clock signal for outputting a second clock signal CLK2.
Read circuit based on the output circuit 16 and the second clock signal CLK2.
LB₁Pit for discriminating the recording track being read
Second sampling corresponding to the sampling timing of
Timing signal SMP2, read beam LB ₁Playback signal by
Sampling corresponding to the recording position of wobble pit A
Reproduction sampling timing signal corresponding to timing
A₁And reproduction sampling timing signal A_TwoOutput
A second timing control circuit 17 for performing
Sampling of reproduction signal B based on timing signal SMP2
And hold the sampling signal A_HLDThe first server that outputs
Sampling hold circuit 15 and reproduction sampling tie
Mining signal A₁Or playback sampling timing signal
B₁Either reproduction signal A or reproduction signal B based on
Sampling and holding, sampling signal SP₁Out
A first reproduction signal sampling and holding circuit 20 to
Reproduction sampling timing signal A_TwoOr play sump
Ring timing signal B_TwoBased on the reproduced signal A or
Sampling and holding any of the raw signals B
Ring signal SP_TwoThe second playback sampling horn that outputs
Circuit 21 and the sampling signal A_HLDAnd sump
Ring signal B_HLDOutput the selection signal SEL based on
The selection circuit 19 and the reproduction signal A based on the selection signal SEL.
Or a first switch for selectively outputting a reproduction signal B
SW₁And playback sampling based on the selection signal SEL
Timing signal A₁Or playback sampling timing
Signal B₁Switch SW that selectively outputs
_TwoAnd the reproduction sampling time based on the selection signal SEL.
Mining signal A_TwoOr playback sampling timing signal
B_TwoChangeover switch SW for selectively outputting data_ThreeAnd the second
One reproduction signal sampling and holding circuit 19 and the second reproduction signal
Output sampler of raw signal sampling hold selection circuit 20
The difference between the ring signals is calculated, and the tracking error signal TE and
And a subtractor 22 that outputs the result.

Next, the operation of generating a tracking error signal will be described with reference to FIGS. First, FIG.
(A), the read beam LB ₁ is trace the recording track TR _{2n + 1,} the read beam LB ₂ will be described to trace over the recording tracks TR _{2n + 2.}
In this case, it is assumed that each servo pit has a position shift (shift amount: Δx) due to rotational jitter or the like of the recording apparatus during wobble pit recording. FIG. 6 (a)
, The delay time _Td between the reading beams is displayed as corrected.

First, the recording track TR_{2n + 2}Read
LB_Two1st clock signal obtained when reproduced by
Reproduction sampling timing signal corresponding to signal CLK1
B₁, B _TwoThe same timing as the timing of
When the wobble pit is not misaligned,
Consider the case where the reproduction signal A is sampled by
Considering this, the curve of the reproduced signal A in FIG.
As shown by the “x” mark, the wobble pit PW_Two'and
Wobble pit PW₁The detected peak of
This means that the wobble pit PW_Two’For Sump
Ring timing shifts and correct tracking
The error signal TE cannot be obtained.

Therefore, in this embodiment, a sampling signal B _HLD obtained by sampling the reproduction signal B by the first sampling and holding circuit 15 by the first sampling timing signal SMP1 and a second sampling timing signal SM
The reproduction signal A is converted to the second sampling and hold circuit 1 by P2.
The selection circuit 19 compares the sampled signal A _HLD sampled by the selector 8 and outputs a selection signal SEL.

[0051] This selection signal SEL, when the sampling signal A _HLD is higher than the sampling signal B _{HL D,} the first changeover switch SW _1, a second changeover switch SW
_Second and third changeover switch SW ₃ is switched to the terminal T ₁ side, the sampling signal A _{HL D} sampling signal B
If it is smaller than _HLD , the first changeover switch SW ₁ ,
The second changeover switch SW ₂ and the third changeover switch SW ₃
It is switched to the terminal T ₂ side.

[0052] Specifically, when, as shown in FIG. 6 (b), the sampling signal A _HLD sampling signal B _HLD
Is smaller than the first switch SW ₁
Is switched to the reproduction signal B side, the second changeover switch SW ₂ is switched to the sampling timing signal B ₁ side, the third changeover switch SW ₃ is so that the switching to the sampling timing signal B ₂ side.

[0053] Accordingly, the first reproduction signal sample and hold circuit 20, a timing based on the sampling timing signal B _1, i.e., in the pulse number = 5 (Fig first clock signal CLK1 shown in FIG. 6 (b), by circled numbers shown. in the corresponding timing with the rise of) samples the peak value of the wobble pits PW ₂ of the reproduction signal B, and outputs it as a sampling signal SP _1. The second reproduced signal sample and hold circuit 21, a timing based on the sampling timing signal B _2, i.e., FIG. 6
Pulse number of first clock signal CLK1 shown in (b) = 3
(Shown by circled numbers.) In the corresponding timing to the rising samples the peak value of the wobble pits PW ₁ of the reproduction signal B, and outputs the sampling signal SP _2.

As a result, the subtractor 22 outputs the following equation.
A racking error signal TE is obtained and output. TE = SP₁―SP_Two Specifically, the reading beam LB_TwoThe recording track that is playing
Tuck TR_{2n + 2}If it is in the on-track state,
Sampling signal SP₁And sampling signal SP _TwoSignal
The levels are equal, and the tracking error signal TE = 0
Becomes

Further, the read beam LB ₂ is applied to the recording track T
When shifted to R _{2n + 3} side, the size is on-track state of the sampling signal SP ₂ is read peaks (FIG. 6 (b)
Reference)). On the other hand, the sampling signal SP ₁ is increased as compared the magnitude of the read peak and on-track state (see Figure 6 (b)). As a result, the tracking error signal TE becomes TE = SP ₁ −SP ₂ <0, and it is possible to detect that the read beam LB ₂ has shifted to the recording track TR _{2n + 3} and the amount of the shift.

When the read beam LB ₂ is at the recording track TR
When shifted to _{2n + 1} side, the sampling signal SP ₂ becomes larger than the size of the read peak and on-track state (see Figure 4 (b)). On the other hand, the sampling signal S
P ₁ is the magnitude is on-track state of a read peak (Fig. 6
(See (b)). As a result, the tracking error signal TE becomes TE = SP ₁ −SP ₂ > 0, and it is possible to detect that the read beam LB ₂ has shifted to the recording track TR _{2n + 1} side and the amount of the shift.

Next, the case where the optical disc has made another rotation from the state shown in FIG. 6 and the recording position has shifted again will be described with reference to FIG. Figure 7 shows the case where the read beam LB ₁ is trace the recording track TR _{2n + 2,} the read beam LB ₂ is tracing over the recording track TR _{2n + 3.} Specifically, FIG.
In the case shown in (b), since the sampling signal A _HLD is larger than the sampling signal B _HLD , the first switch SW ₁ switches to the reproduction signal A side and
The changeover switch SW ₂ is connected to the sampling timing signal A ₁
Switched to the side, third changeover switch SW ₃ is so that the switching to the sampling timing signal A ₂ side. Accordingly, the first reproduction signal sample and hold circuit 20, a timing based on the sampling timing signal A _1, i.e., the pulse number = 5 in the second clock signal CLK2 shown in FIG. 7 (b) (in the figure, indicated by circled numbers.) in the corresponding timing to the rising samples the peak value of the wobble pits PW ₂ of the reproduced signal a, and outputs it as a sampling signal SP _1. The second reproduced signal sample and hold circuit 21, a timing based on the sampling timing signal A _2, i.e., the pulse number = 3 of the second clock signal CLK2 shown in FIG. 7 (b) (in the figure, indicated by circled numbers.)
In the corresponding timing to the rising samples the peak value of the wobble pits PW ₁ of the reproduction signal B, and outputs the sampling signal SP _2.

Thus, the subtractor 22 outputs the read beam L
If the B ₁ is in the on-track state on the recording track TR _{2n + 2} being reproduced, the signal level of the sampling signal SP ₁ and the sampling signal SP ₂ are equal, the tracking error signal TE = 0.

Further, the reading beam LB ₁ is applied to the recording track T
When the sampling signal SP ₂ shifts to the R _{2n + 3} side, the magnitude of the read peak of the sampling signal SP ₂ is in the on-track state (FIG. 7B).
Reference)). On the other hand, the sampling signal SP ₁ is increased as compared the magnitude of the read peak and on-track state (see FIG. 7 (b)). As a result, the tracking error signal TE becomes TE = SP ₁ −SP ₂ <0, and it can be detected that the read beam LB ₁ has shifted to the recording track TR _{2n + 3} and the amount of the shift.

When the read beam LB ₁ is at the recording track TR
When shifted to _{2n + 1} side, the sampling signal SP ₂ becomes larger than the size of the read peak and on-track state (see FIG. 7 (b)). On the other hand, the sampling signal S
P ₁ is the magnitude is on-track state of a read peak (Fig. 7
(See (b)). As a result, the tracking error signal TE becomes TE = SP ₁ −SP ₂ > 0, and it is possible to detect that the read beam LB ₁ has shifted to the recording track TR _{2n + 1} and the amount of the shift.

FIG. 8 shows a specific example of the tracking error signal TE.
Here is an example. As shown in FIG. 8, the tracking error signal
TE is the reading beam LB₁Is output when using
1 tracking error signal TE₁(See FIG. 8 (a))
And reading beam LB_TwoThe second token output when using
Racking error signal TE _Two(See FIG. 8B)
Pit P_DPit output signal corresponding to the presence or absence of
(C) (see FIG. 8 (e))
Reference). Concrete
Specifically, the recording track TR_2nOf light beam LB_TwoTo
(See FIG. 8 (f)).
Signal TE_TwoAs the tracking error signal TE
No, recording track TR_{2n + 1}When performing playback of the first
Racking signal TE₁With the tracking error signal TE
And use the recording track TR_{2n + 2}When playing back
Second tracking signal TE_TwoThe tracking error signal
Used as TE, recording track TR_{2n + 3}Place to play
The first tracking signal TE₁Tracking error
-Used as signal TE.

As described above, the wobble pit (PW ₁
And PW ₂ ), a tracking error signal is generated based on a reproduced signal of a light beam tracing on a recording track provided with a wobble pit even when a wobble pit is not provided. A correct tracking error signal TE can always be obtained without being affected by a shift in the wobble pit recording position due to rotational jitter or the like of the recording apparatus during recording, and tracking control can be performed reliably.

In the above-described first embodiment, wobble pits are provided in segments of even-numbered recording tracks. However, it is also possible to provide wobble pits in segments of odd-numbered recording tracks. Also, discrimination pits P _D may be configured to provide a recording track side not provided with wobble pits. In the second embodiment the first embodiment, pits for discriminating the segment in which a wobble pit P _D and the clock pit C
It has been provided both P, but the present second embodiment is an embodiment in which also serves as a clock pit CP 'as discriminating pits P _D of the first embodiment.

FIG. 9 shows the recording format of the optical disk according to the second embodiment. Recording tracks TR _{2n-1 to} TR _{2n + 4} (recording track number 2n) adjacent in the radial direction of the optical disc
The clock pit area ACP, the wobble pit area AWP, and the data area ADT for recording various data are provided in order from -1 to 2n + 4, where n is a natural number, as viewed from the disk rotation direction (upper side in the drawing). Have been.

In the following description, the above-mentioned clock pit area ACP and wobble pit area AWP are combined to form a servo area ASV. Clock pit area AC
In P, a segment provided with a wobble pit described later indicates that the segment is provided with a wobble pit described later and a clock pit CP 'indicating clock generation timing is provided.
Specifically, in FIG. 9, clock pits CP are provided in segments on recording tracks TR _2n , TR _{2n + 2} , and TR _{2n + 4} having even-numbered recording track numbers.

In the wobble pit area AWP, wobble pits PW ₁ and PW ₂ used for generating a tracking error signal are provided on both sides (between recording tracks) of every other recording track.

Next, the configuration of a main part of a reproducing apparatus for obtaining a tracking error signal using the optical disk of FIG. 9 will be described with reference to FIG. 10, the same parts as those in the first embodiment of FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The reproducing apparatus 10A shown in FIG. 10 is the same as the reproducing apparatus shown in FIG.
The difference from FIG. 10 is that the main beam, ie, the read beam LB_TwoOr
A playback signal B, which is a playback signal of the
The first clock based on the sampling timing signal
A first clock extraction circuit 13A that outputs a signal CLK1,
Read beam LB based on one clock signal CLK1_TwoReading
Clock pit sampling of the recording track
First clock sampling time corresponding to timing
Scanning signal CSMP1, reading beam LB_TwoOf the reproduced signal B
The playback sampling time corresponding to the sampling timing
Imming signal B ₁And playback sampling timing signal
Issue B_TwoA first timing control circuit 14A that outputs
Based on one clock sampling timing signal CSMP1
The reproduction signal B is sampled and held, and the sampling signal
Issue B_HLD1st sampling and hold circuit 15 which outputs
A and reading beam LB₁Playback signal that is the playback signal from
A and a second clock sampling signal described later.
The second clock extraction circuit that outputs the second clock signal CLK2
Path 16A and the read beam based on the second clock signal CLK2.
Mu LB₁Clock pit of recording track being read
The second clock sample corresponding to the sampling timing of
Pulling timing signal CSMP2, read beam LB₁By
Playback corresponding to the sampling timing of the playback signal A
Sampling timing signal A₁And regenerated sampler
Timing signal A_TwoOutput the second timing control circuit
Path 17A and the second clock sampling timing signal
The playback signal B is sampled and held based on CSMP2,
Sampling signal A_HLDOutput the second sampling
And a threshold circuit 18A.

Next, the operation of generating a tracking error signal will be described with reference to FIG. First, FIG.
(A), the read beam LB ₁ is trace the recording track TR _{2n + 1,} the read beam LB ₂ will be described to trace over the recording tracks TR _{2n + 2.}
In this case, it is assumed that each servo pit is displaced (displacement amount: Δx ″) due to rotational jitter of the recording device that occurs during wobble pit recording. In addition, in FIG. Delay time _Td
Is displayed as corrected.

First, a second clock signal obtained when the recording track TR _2n is reproduced by the read beam LB ₁
The reproduction sampling timing signal B ₁ corresponding to CLK2,
Considering the case where the reproduction signal A is sampled based on B ₂ , the wobbled pits PW ₂ ′ and the wobble pits PW ₂ ′ are indicated on the curve of the reproduction signal A in FIG. becomes sampling the detected peak of the pit PW _1, it is impossible to obtain a correct tracking error signal TE becomes the sampling timing is deviated for the wobble pits PW ₂ '.

Therefore, in the second embodiment, a sampling signal B _HLD obtained by sampling the detection peak of the clock pit CP in the reproduction signal B by the first sampling and holding circuit 15A by the first clock sampling timing signal CSMP1 and the second clock The selection circuit 19 compares the detection peak of the clock pit CP in the reproduced signal A with the sampling signal A _HLD sampled by the second sampling and holding circuit 18A by the sampling timing signal CSMP2 and outputs the selection signal SEL.

In parallel with this, the first clock extracting circuit 13
A and the second clock extraction circuit 16A compare the phase with a preset reference clock when the read beam corresponding to the recording track on which the clock pit CP is recorded reproduces the clock. Extraction is performed and a clock signal is output. Also, the clock pit CP
When the corresponding read beam is reproducing the recording track on which no is recorded, the phase comparison is not performed and the signal is output while holding the previous clock signal.

Next, sampling is performed based on the selection signal SEL.
Signal A_HLDIs the sampling signal B _HLDPlace larger than
In other words, the reading beam LB_TwoNote that is traced
Clock pit CP 'is provided on the recording track side
In the case, the first changeover switch SW₁, Second switch
SW_TwoAnd third switch SW_ThreeTo terminal T₁Cut to the side
Can be replaced. Also, the sampling signal A_HLDIs a sampler
Signal B_HLDIs smaller than
Mu LB₁Clock on the recording track side
If a pit CP is provided, the first switch
Switch₁, Second switch SW_TwoAnd third switch
Switch_ThreeTo terminal T_TwoIt is switched to the side.

Specifically, in a case as shown in FIG.
The sampling signal A_HLDIs the sampling signal B
_HLDIs smaller than the first switch S
W₁Switches to the reproduction signal B side, and the second switch SW
_TwoIs the sampling timing signal B₁Switch to the side
3 changeover switch SW_ThreeIs the sampling timing signal B
_TwoWill switch to the side. At the same time, the first clock
The clock extraction circuit 13 detects the clock pit CP '.
As a result, the first clock signal CLK1 is
Extract (update). On the other hand, the second clock extraction circuit 16
Has not been detected since the clock pit CP was detected.
The phase of the extracted second clock signal CLK2 is held.

Therefore, the first reproduction signal sampling and holding circuit 20 performs the timing based on the sampling timing signal B ₁ , that is, the first reproduction signal sampling and holding circuit 20 shown in FIG.
(Shown by circled numbers.) Pulse number = 2 of the clock signal CLK1 at the corresponding timing to the rising samples the peak value of the wobble pits PW ₂ of the reproduction signal B, and outputs the sampling signal SP _1. The second reproduced signal sample and hold circuit 21, a timing based on the sampling timing signal B _2, i.e., 4
The pulse number of the first clock signal CLK1 shown in FIG.
(Shown by circled numbers.) In the corresponding timing to the rising samples the peak value of the wobble pits PW ₁ of the reproduction signal B, and outputs the sampling signal SP _2.

Thus, the subtractor 22 calculates and outputs the tracking error signal TE according to the following equation. TE = SP ₁ -SP ₂ According to the second embodiment, the clock pit CP ′ is provided for every other recording track. Therefore, in addition to the effect of the first embodiment, the influence of the clock pit of the adjacent recording track is provided. And a stable clock signal can be obtained even when the recording track pitch is narrow.

In the second embodiment, the clock pit CP 'is provided in front of the wobble pits PW ₁ and PW ₂ (left side in FIG. 9), but behind the wobble pit (right side in FIG. 9). And between the wobble pits.

[0078]

According to the first aspect of the present invention, the track
Segment with pits for king error signal generation
The tracking error is applied to the segment radially adjacent to
-Since there is no signal generation pit,
Even when playing an optical disc with a pitch, adjacent segments
Of the pit for generating the tracking error signal
Due to rotational jitter generated during recording
Deviation of recording position of pit for generating tracking error signal
Tracking error signal without being affected by
Can be generated.

According to the second aspect of the present invention, the track
Segment with a pit for generating
Tracking error in radially adjacent segments
Since no signal generation pits are provided, narrow tracks
When playing back an optical disc with a pitch,
Of the tracking error signal generation pit
Pit for clock extraction
Segments that are radially adjacent to the
Because there is no lock extraction pit,
Even when playing an optical disc with a pitch, adjacent segments
Interference from the clock extraction pit
Tracking due to rotational jitter, etc. generated during recording
Pits for generating error signals and pits for extracting clocks
Correct track without being affected by the recording position
Can generate king error signal and clock signal
it can.

[0080]

[0081]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a recording format of an optical disc according to a first embodiment.

FIG. 2 is a diagram (1) illustrating a schematic configuration of the optical disc of FIG. 1;

FIG. 3 is a diagram (2) illustrating a schematic configuration of the optical disc in FIG. 1;

FIG. 4 is a diagram (3) illustrating a schematic configuration of the optical disc of FIG. 1;

FIG. 5 is a block diagram showing a main part of the playback device of the first embodiment.

FIG. 6 is a diagram (1) illustrating the operation of the first embodiment.

FIG. 7 is a diagram (2) illustrating the operation of the first embodiment.

FIG. 8 is an explanatory diagram of a tracking error signal.

FIG. 9 is a diagram illustrating a recording format of an optical disc according to a second embodiment.

FIG. 10 is a block diagram illustrating a main part of a playback device according to a second embodiment.

FIG. 11 is a diagram illustrating the operation of the second embodiment.

FIG. 12 is a diagram illustrating a recording format of a sampled servo system.

FIG. 13 is a diagram illustrating a recording format of a conventional servo area.

FIG. 14 is a diagram illustrating tracking error detection using a conventional wobble pit.

FIG. 15 is a diagram illustrating a conventional problem.

FIG. 16 is a diagram illustrating a proposal for solving a conventional problem.

FIG. 17 is a diagram illustrating points to be improved in the proposal of FIG. 16;

[Explanation of symbols]

Reference Signs List 10 playback apparatus 11 crosstalk canceller 12 decoder 13 and 13A first clock extraction circuit 14, 14A first timing control circuit 15, 15A first sampling and holding circuit 16, 16A second clock extraction circuit 17, 17A: second timing control circuit 18, 18A: second sampling and holding circuit 19: selection circuit 20: first reproduction signal sampling and holding circuit 21: second reproduction signal sampling and holding circuit 22: subtractor A, B, C: reproduction signal ACR ... clock pit area ATR ... tracking pit area ASV, ASV _1, ASV ₂ ... servo area CP ... clock pit DK ... optical disc LB ₂ ... read beam (main beam) LB ₁ ... read beam (sub-beam) TE ... tracking error signal TR _{2n-1 to} TR _{2n + 4} … Record truck

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/09-7/095 G11B 7/085 G11B 20/12

Claims (2)

(57) [Claims] A recording track formed substantially concentrically;
Data information for recording data information in each recording track
The area and the servo control information for recording the servo control information
In the provided sampled servo type optical disc
The number of segments constituting the recording track
M · (2n + 1) [m: natural number, n: 0, 1,
2,...] And are continuous every m segments.
For generating a tracking error signal on m segments
A pit is provided and the tracking error signal generation
All segments provided with
All segments that do not have pits for
In the servo control information area of one of the contacts.
To indicate the presence or absence of a pit for racking error signal generation
A pit for discrimination is provided, and the servo control for all segments is performed.
Clock pit for clock extraction is provided in the control information area
Using an optical disc and at least two reading beams
Tracking error that generates a tracking error signal
A signal generator for detecting a read beam on an adjacent recording track.
Reproduction signal level corresponding to the recording position of the discrimination pit
And the tracking error signal generation pit is
A reading window that scans the formed recording track
Determination means for determining the reproduction signal of the beam, and tracking based on the determined reproduction signal of the read beam.
Calculating means for calculating and outputting a king error signal; and generating a tracking error signal.
apparatus. 2. A recording track is formed substantially concentrically.
Data information for recording data information in each recording track
The area and the servo control information for recording the servo control information
In the provided sampled servo type optical disc
The number of segments constituting the recording track
M · (2n + 1) [m: natural number, n: 0, 1,
2,...] And are continuous every m segments.
For generating a tracking error signal on m segments
A pit is provided and the tracking error signal generation
All segments provided with
All segments that do not have pits for
In the servo control information area of one of the contacts.
Indicates whether there is a pit for generating racking error signal and
A discrimination clock pit for clock extraction
At least two reading beams using a radiated optical disk
Tracking signal that generates tracking error signal using
A write error signal generating device, comprising:
Reproduction signal corresponding to the recording position of the discrimination clock pit
The levels are compared and the tracking error signal
Scanning on the recording track where
Determining means for determining the reproduction signal of the taking beam; and tracking based on the determined reading signal of the reading beam.
Calculating means for calculating and outputting a king error signal; and generating a tracking error signal.
apparatus.