JPS63298870A - Signal reproducing system - Google Patents

Abstract

PURPOSE:To attain highly reliable data reproduction by providing a strobe signal triggered by a signal selected by a selection circuit. CONSTITUTION:The selection circuit 67 selects a PLL 63 for reproduction RF signal just after the steady-state of revolution of an optical disk. As a result, a selecting state passing through a synchronizing signal by a clock bit and a selecting state passing through the synchronizing signal by a reproducing data exist and any synchronizing signal is sent to the strobe circuit 39. The strobe circuit 39 segments an output signal from a comparator 37 by using either of synchronizing signals and the result is sent to a demodulation circuit and a sector address (ID) detection circuit 40 and the ID detection circuit 40 applies a processing extracting only the ID from the reproducing signal string. Thus, highly reliable data reproduction is realized independently of the fluctuation of driving motor, mounting error of medium, the variation of recording characteristic of an inner face of the medium or the change with the lapse of time such as deflection or bent.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a signal reproduction method for information recorded on an optical disk, and is particularly suitable for use in an information recording and reproducing apparatus that records and reproduces information using a sample servo method. This invention relates to a suitable signal reproduction method.

<Prior art and its problems> Recently, optical disks have been attracting attention and research as information recording media capable of high-density recording. Optical discs can be divided into write-once optical discs and rewritable optical discs, but both types of optical discs require a tracking servo to follow tracks formed on the optical disc during recording and playback by an information recording/playback device. Can be applied.

As a tracking servo method, a so-called pre-group method that traces a tracking groove has traditionally been used, but a so-called sample servo method is being used from the viewpoint of servo stability and ease of yim.

The format of an optical disc using the sample servo method will be explained with reference to FIG. In FIG. 6, a track 2 formed on an optical disc 1 has a plurality of sectors 3 along the circumferential direction.
Each sector 3 contains an ID (sector address) field 4 and data fields 5, 6°7, -8.
(Di, D2.D3.-Dm), and the servo unit 9 has a servo area 1 having a tracking pit 12 and a clock pit 14.
0 and a data area 11. therefore,
One track consists of multiple sectors 3 and each sector has a number of 10
Since the servo unit 9 is made up of servo units 9, normally 1000 or more servo areas 10 are formed per track. As a result, tracking servo using the sample servo method is performed by obtaining a tracking error signal from the servo pit 12 in the servo area 10. Note that for focusing servo at the distance between the lens and the signal surface of the optical disk, a focusing error signal is obtained from the entire surface of the medium.

In this way, in the sample servo method, the servo area 10 and the data area 11 are separated and independent as shown in FIG. 6, so even after information is recorded in the data area 11, there is no interference of the servo signal, resulting in stable tracking control. can be done.

However, in the sample servo system, the periodic signal for the entire optical disk is obtained from the clock pit 14 formed at the rear end of the servo area 10, so when the information reproduction system is synchronized at the clock pit 14, As shown in FIG. 7, in the reproduced signal (READ-SIG), a time axis error of Sl occurs due to clock jitter, resulting in a disadvantage that the window margin decreases.

To comment, Fig. 7 shows the clock pit signal (CLKPIT-3IG) that generates the reference timing for recording and reproduction in the sample servo system, the recording synchronization signal (WRITE-SIG) obtained in synchronization with this, and the timing during reproduction. The correlation with the obtained reproduction synchronization signal (READ-3IG) is shown. Since the clock pits 14 usually appear only at intervals of several tens of bytes beyond the data area, a continuous clock signal synchronized with the clock pits 14 will have a considerable time axis error due to motor rotation fluctuations and the like. Similarly, the reproduction synchronization signal also has a time axis error of Sl with respect to the clock pit 14. Therefore, a time axis error S between the recording synchronization signal and the reproduction synchronization signal is also unavoidable.

These errors can become large due to factors such as errors in mounting the optical disk, changes in eccentricity, warping, etc., changes in various physical characteristics over time, and variations between devices. This x difference s appears as skew jitter in the reproduced signal and reduces the window margin of one piece of information. In particular, in edge recording where the timing of the rise and fall of a reproduced RF signal is used as an information point, problems arise in that the skew increases, the phase margin significantly decreases, and the error rate worsens.

In view of the above-mentioned problems, the present invention provides a signal reproducing method that increases the window margin, improves the error rate, and obtains high reliability in the information reproducing method using the sample servo method.

<Means for Solving the Problems> The present invention, which achieves the above-mentioned object, provides a signal reproduction method for an information processing device that records and reproduces data using a sample servo pattern and a synchronization pattern. an optical recording medium in which data of an arbitrary pattern is recorded on a medium in which a servo area consisting of a pattern is pre-pit recorded; a phase-locked loop 1 that synchronizes with the synchronization pattern on the recording medium; a phase-locked loop 2 that synchronizes with the data recording signal that has been recorded, and a phase-locked loop 2 that achieves tracking and focusing during playback, reproduces a desired track, detects a steady state, and transfers the output signal of the phase-locked loop 1 to the phase-locked loop 2. A selection circuit that switches to an output signal, a strobe circuit that is triggered by the signal selected by the selection circuit, and a sector ID detection circuit. The selection circuit is switched using an AND signal of the sector ID detected signal, the signal envelope detection signal, the lock completion signal of the phase locked loop 2, and the pass detection signal of the servo area at the beginning of the sector. As a time point, when passing through the servo area after the second servo area of the sector to be reproduced which is in a steady state, it is assumed that the special effects are as follows.

Function〉 The strobe signal that extracts only the necessary data reproduction signal is obtained from the clock bit in the servo area.
Thereafter, a strobe signal can be obtained from the recorded data itself.

<Example> The present invention will now be described in detail with reference to FIGS. 1 to 5. 1 to 3 show an embodiment of the present invention. FIG. 1 shows an outline of a recording/reproducing apparatus for a write-once optical disc, in which a recording system into which recording information (W-DATA) is input includes a modulation circuit 30, a recording correction circuit 31, a laser drive circuit #J32, and an optical It consists of a head 33 and a modulation circuit 3.
0, the binary recording data that is the recording information is, for example, 2to7.
(Run length limited code) is converted into 2t07 recording bits. Next, the 2 to 7 recording pits are corrected to a signal for pit formation via the recording correction circuit 31, and the laser drive circuit 32 operates based on this correction signal. Then, the power of the semiconductor laser in the optical head 33 is converted, and recording bits corresponding to recording information (W-DATA) are formed on the optical disk 1.

A tracking and focusing servo circuit 34 is connected to the optical head 33, so that tracking servo and focusing servo are performed on the optical head 33 at a tracking pit or the like.

The reproduction system from which reproduction information (R-DATA) is output includes an amplification circuit 1535, an equalization circuit 36, a comparator 37, a synchronization signal generation circuit 38, a strobe [1#39, and an ID detection 1
It consists of a demodulation circuit 41. Here, the pit reproduction signal obtained from the optical head 33 is input to the equalization circuit 36 via the amplifier circuit 35. The equalization circuit 36 performs waveform shaping to stabilize the impulse response. Then, the comparator 37 binarizes the waveform-shaped signal at an appropriate slice level. Then, comparator 3
The binary data that is the output of 7 is sent to the synchronization signal generation circuit 38 and the strobe circuit H839, and the synchronous signal generation circuit 3
8 is a clock pit PLL (PLL) which extracts the clock pit in the servo area and generates a continuous signal synchronized with the four clocks, which will be explained in more detail later in FIG.
LC) and a reproduction RF signal PLL (PLL-D) that generates a signal synchronized with the overall data based on the data bits in the data area. Initially, the strobe circuit was activated using the clock pit PLL signal. A strobe signal is generated within the controller 39, and the strobe signal is then generated in the reproduced RF signal PLL by synchronizing the entire data.

The strobe circuit 39 punches out the binary data from the comparator 37 using the strobe signal, and sends this punched data to the ID detection circuit 40 and demodulation circuit 41. Then, the ID detection circuit 40 extracts only the ID from the reproduced signal, and the demodulation circuit 41 modulates the data based on the 2 to 7 modulation/demodulation rule.

Here, the synchronization signal generation circuit 38 will be mainly explained with reference to FIG. In FIG. 2, 37 is a comparator, 38 is a synchronization signal generation circuit, 39 is a strobe circuit, and 40 is an ID detection circuit. Further, the synchronization signal generation circuit 38 is divided into a clock pit PLL 62 and a reproduced RF signal PLL 63. Each of the PLLs 62 and 63 has a phase comparator 80p81, filters 82 and 83, a voltage controlled oscillator (VCO) 84°85, and a lock detection @86.
．． 87, and furthermore, in the PLL 62, a frequency dividing circuit 8
It has 8.

The RF multiplied signal after waveform shaping passes through the comparator 37, and only the clock pit signal passes through the clock pit gate 60 to operate the PLL 62, while the RF data signal itself operates the PLL 63.

When the optical disc is reproduced, an RF multiplied signal is input to the comparator 37, and when the clock pit signal passes from the clock pit gate 60, for example, when the power is turned on, the REF signal is input to the comparator 37.
-The phase comparator 80 of the PLL 62, which is locked by CLK, detects a clock pip! - Generates a voltage proportional to the phase difference caused by the signal, transmits this voltage to the VcO84 via the filter 82, outputs a signal with an oscillation frequency proportional to the input voltage at the VC084, and divides this oscillation signal. It is fed back through the circulation circuit 88. In this case, the clock pit signal is regenerated intermittently, so the intermediate clock is V
Interpolate with the output of CO84. In this way, a continuous signal synchronized with the intermittent input signal is output from the PLL 62. The waveform shown in Figure 3 shows this situation, and the CLK
-PIT is the clock pit signal, xN is the VCO before division
The output of 84, PLLC-OUT, is the output of PLL 62. Note that when the frequency is locked, an output is obtained from the lock detector 86.

While the PLL 62 is operating according to the clock pit signal, the output signal of the PLL 62 is inputted as the reference signal of the PLL 63, and the output signal of the PLL 62 is output from the PLLC-O.
Obtained UT. Here, when the reproduced RF data is input via the combinator 37, the PLL 6
The frequency is fixed in step 3. In this state, synchronization is applied by the reproduced RF data in the data area, and the PLL
G 3 (7) A synchronization signal based on a data signal is obtained from vC085 as an output. And the four-piece detector 87
Obtain lock output.

In Figure 3, the output of PLL 63 is PLLD -0
It is UT.

The selection signal generation circuit 100 controls the RF multiplied signal acquisition selection circuit 67 after waveform shaping. That is,
As long as tracking servo or focusing servo is obtained for a desired track and the RF signal to be reproduced is in a steady state, the selection circuit 67 is a circuit that obtains an output that selects the output of the PLL 63.

Immediately after the rotation of the optical disk becomes steady, the selection circuit 67 selects the PLL 63.

As a result, there is a selection state in which a synchronization signal is passed by the clock pit and a selection state in which a synchronization signal is passed by the playback data. For example, at the beginning of the rotation of an optical disk, the former is
During steady reproduction of the signal, the second winding is selected and one of the synchronizing signals is sent to the strobe circuit 39.

In the strobe circuit 39, the output signal from the comparator 37 is affected by one of these synchronization signals, and then, as described above, it is sent to the demodulation circuit 41 and the ID detection circuit 40, and the ID detection circuit 40 reproduces the reproduced signal sequence. The process of extracting only TD from is done.

Using the above two systems of clock signals, in the reproduction operation of a desired sector, a strobe signal synchronized with the bit clock signal is used at the initial stage such as when starting up the device.
Once a pre-pit section such as the D section is reproduced and a clock signal is synchronized with the recording data signal itself, a strobe signal based on this is used to reproduce the signal.

FIGS. 4 and 5 are other more specific embodiments of the present invention, and portions different from those in FIG. 2 will be explained. The selection signal generation circuit includes an envelope detection circuit 64 for detecting the presence or absence of a reproduced RF signal, a servo unit passage detection circuit 65 after the data field D1, and an AND circuit 66. The envelope detection circuit 64 receives the RF signal and detects the envelope of the reproduced signal waveform, resulting in the ENV-DTC waveform shown in FIG. The servo unit passage detection circuit 65 receives the ID detection signal ID- of the desired sector.
DTC (see Figure 5) and PL for servo area detection
With the output signal of L 62 as input, a detection signal S V -PASS (see FIG. 5) is generated when reproducing the servo area. Therefore, the AND circuit 66 uses the lock detection signal PLLD- of the PLL 63 for steady state detection.
ROCK and the 10 detection signal ID-D of the ID detection circuit 40
TC, the output signal S V -PASS of the servo unit passage detection circuit 65 after the data field D1, and the output signal ENV-DTC of the envelope detection circuit 64 are used as input signals to obtain a logical product. Therefore, in the selection signal generation circuit 100, the steady state by the desired sector is detected by the presence of the RF signal, the detection of the servo area of the desired sector, the synchronization by the clock pit, and the lock of PLI 63 for steady state detection. Become. AND of the above 4 items
During the period when the conditions are satisfied, the output of the AND circuit 66, that is, the output of the selection (number 3 generation time #1100) becomes High as shown in FIG.

As a result, the output of PLL 63 is selected in selection circuit R867. Naturally, the selection circuit 67 selects the output of the PLL 62 during a period when the above AND condition is not satisfied.

PLL 62 or PLL 6 selected by selection circuit 67
The output of No. 3 is input to the C1 strobe circuit 39 as in the first embodiment, and the output signal of the comparator 37 is punched out. The output of this strobe circuit 39 is sent to an ID detection circuit 40 and a demodulation circuit 41.

In the above description of the second embodiment, the AND condition is set to four signals, namely ENV-DTC, TD-DTC, and PLLD.
-ROCK and 5V-PASS, but these conditions can be changed as appropriate depending on the desired reliability, such as excluding envelope detection.

In addition, PLLs 62 and 63 each have a phase comparator 80.8.
1, but it is also possible to use one phase comparator in time and minutes.

Furthermore, although the above embodiments have been described assuming a write-once type optical disk, it is of course applicable to rewritable type optical disks such as a magneto-optical type or a phase change type.

Further, the modulation method is not limited to the 2 to 7 method, and the pattern form and recording method of the servo pattern and synchronization pattern can be selected as appropriate.

<Effects of the Invention> As explained above, according to the present invention, since a strobe signal is generated in synchronization with the recording signal itself of the sector to be reproduced, fluctuations in the rotating motor, errors in mounting the medium, and in-plane errors in the medium can be avoided. The advantage is that highly reliable data reproduction can be realized regardless of variations in recording characteristics and changes over time such as eccentricity and warpage.

Furthermore, data reliability can be sufficiently ensured even if a medium recorded by one drive is reproduced by different drives having different mechanical characteristics.

In particular, it is possible to suppress variations in the reproduction signal pulse width, which is a problem when edge recording is performed on an optical disk, so there is an advantage that the phase margin characteristics are significantly improved.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of the recording and reproducing system of a write-once optical disc.
FIG. 2 is a circuit block diagram representing the first embodiment that best represents the features of the present invention, FIG. 3 is an operation timing chart of FIG. 2, and FIG. 4 is a circuit representing the second embodiment. 5 is an operation timing chart of FIG. 4, FIG. 6 is an explanatory diagram of the format of the optical disk medium for sample servo, and FIG. 7 is a recording/reproduction timing chart. In the diagram, 1: optical disk medium, 2: track, 3: sector, 4
: ID field (ID), 5: Data field -
1 (D), 6: Data field-2 (D2), 7: Data field-3 (D,), 8: Data field-
([), ), 9: Servo unit, 10: Servo area, 11: Data area, 12: Servo pit, 14:
Four pits, 30: Modulation circuit, 31: Recording correction circuit, 32: Laser drive circuit, 33: Optical head, 34:
Tracking/focusing circuit, 35: Amplification circuit, 36: Equalization circuit, 37: Comparator, 38 Two-synchronization signal generation circuit, 39: Throtobe circuit, 40: ID detection circuit, 41: Demodulation circuit, 60: Clock pit passage gate, 62: PLL for clock pit (PI-L-C
), 63: PLL for reproduction RF signal (PLL-D), 6
4: Envelope/detection circuit for reproduced RF signal, 65:
Data field D, subsequent servo unit passage detection circuit, 66: AND circuit, 67: selection circuit, 80° 81
: Phase comparator, 82.83: Sample; k − k 9”
hl path, 84, 85: vco, 86° 87: lock detection circuit, 88 frequency divider circuit 1.100: selection signal generation circuit. Figure 1

Claims (2)

[Claims] (1) In the signal reproduction method of information processing equipment that records and reproduces data using sample servo and synchronization patterns, an arbitrary pattern is recorded on a medium in which a servo area consisting of a fixed servo pattern and a synchronization pattern is pre-pit recorded. An optical recording medium on which data is recorded; a phase-locked loop 1 that synchronizes with the synchronization pattern on the recording medium; and a phase-locked loop 2 that synchronizes with the data recording signal recorded on the recording medium; a selection circuit that detects a steady state and switches the output signal of the phase-locked loop 1 to the output signal of the phase-locked loop 2 when tracking and focusing are achieved and a desired track is reproduced; and a signal selected by the selection circuit. A signal reproducing method comprising: a triggered strobe circuit; and a sector ID detection circuit. (2) In the signal reproduction method according to claim 1, the selection signal of the selection circuit includes: a detected signal of the ID of the sector to be reproduced, a detection signal of the signal envelope, and a signal of the phase-locked loop 2. Using the AND signal of the lock completion signal and the passing detection signal of the servo area at the beginning of the sector, the servo area after the second servo area of the sector to be reproduced which is in a steady state is determined as the switching point of the selection circuit. A signal regeneration method characterized in that when passing, , and .