JP2000293855A - Pre-pit information detection device for optical disk drive - Google Patents

Abstract

(57) [Problem] To provide information based on a pre-pit signal more accurately even when a noise component is superimposed on a wobbling signal. SOLUTION: A wobbling signal phase comparator 23, a pre-pit phase comparator 24, a switch 27, a VCO 28, and a frequency divider 32 receive an input binary wobbling signal:
Generate a recording clock: VCK synchronized with Swb,
When the synchronization is established, the switch 27 is switched so that the input pre-pit detection signal: the recording clock signal: VCK which is more accurate than that synchronized with the phase of the Spd is output from the pre-pit signal decoding timing signal generator 20, the pre-pit detection signal. The signals are output to the signal encoder 14 and the pre-pit signal detector 19, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a conventional CD (Co)
DVD (Digital Video Disc) with a remarkably improved recording density compared to a compact disk (mpact disk).
k or Digital Versatile Dis
k) of the high-density recording medium represented by k)
O (Write Once) type recording medium (hereinafter referred to as “D
VD-R (DVD-Recordable) ")
In the above, address information necessary for position search or the like at the time of recording information such as image information or rotation control information such as a synchronization signal or wobbling signal used for rotation control of a DVD-R (hereinafter, these are collectively referred to as “ The present invention relates to a pre-pit information detection device of an optical disk drive for detecting pre-information from a DVD-R in which pre-information is recorded in advance.

[0002]

2. Description of the Related Art Conventionally, as a recording medium on which pre-information as described above is recorded in advance and information can be additionally recorded based on the pre-information, an optical disc having a recording capacity similar to that of a compact disc (CD) is used. CD-R (CD
-Recordable) is known.

[0003] In the CD-R, C
The information track (groove track or land track) on which the recording information is to be recorded at the pre-formatting stage at the time of manufacturing the D-R, the pull information to be recorded is set in advance by FM (Freq
The pre-information is recorded by wobbling in a wave form at a frequency corresponding to a signal subjected to the modulation.

When recording information is actually recorded on a conventional CD-R, the wobbling frequency of the wobbled track is detected, and the rotation of the CD-R is controlled based on the detected wobbling frequency. Extract the reference clock,
A reference clock for controlling the rotation of the CD-R is extracted based on the extracted reference clock, and a drive signal for controlling the rotation of a spindle motor for rotating the CD-R is generated based on the extracted reference clock. Along with
A recording clock signal including timing information synchronized with the rotation of the CD-R has been generated.

Further, a CD-R required for recording information is required.
With respect to the address information indicating the above address, the pre-information is reproduced at the time of recording the recording information, and the recording information is recorded by detecting a position to be recorded based on the pre-information.

However, in the above-described DVD-R, the interval between adjacent information tracks is almost half of that of a CD-R due to the demand for higher recording density. Even when trying to obtain pre-information by wobbling an information track on a DVD-R, the wobbling frequencies of adjacent information tracks may interfere with each other and the wobbling frequency may not be accurately detected.

Therefore, in the above-described DVD-R, an information track (for example, a groove track) in the DVD-R is wobbled at a frequency based on the reference clock, and in addition to this, the pre-information is duplicated. Recording is also performed by forming a pre-pit corresponding to the pre-information on a track (for example, a land rack) between the two information tracks.

Further, the pre-pits are formed almost uniformly over the entire surface of the DVD-R so that the reference clock can be reproduced from the preset if necessary. As described above, conventionally, pre-information is obtained by detecting the above-mentioned pre-pits, and accurate rotation control and recording control are performed based on the pre-information.

By the way, detection of prepits in the prior art has been performed by the following method. First, a gate signal synchronized with a signal containing a wobbling frequency component obtained by irradiating the information track with a light beam (hereinafter, referred to as a “wobbling signal”) is generated.

Next, by comparing the wobbling signal with a predetermined threshold signal, only signals exceeding the predetermined threshold signal are extracted. Then, a pre-pit signal superimposed on the wobbling signal is extracted by taking the logical product of the extracted signal and the gate signal.

Therefore, when dust or dirt adheres to the optical disk, or when crosstalk occurs from other signals recorded on the optical disk, noise is mixed into the wobbling signal, and this noise is detected by the pre-pit detection. In some cases, it was erroneously detected as a signal.

As a result, it is not possible to accurately obtain address information or synchronization signal information necessary for a position search or the like when recording information is recorded, and a recording device using a DVD-R or the like may malfunction. Was.

Therefore, there has been a demand for a device which can accurately obtain information based on a pre-pit signal when a noise component is superimposed on a wobbling signal.

Conventionally, when it is detected that a wobbling signal on which a pre-pit signal is not superimposed is repeated five times in eight cycles of a wobbling signal, detection of the pre-pit signal is performed within three cycles of the wobbling signal. There is an apparatus that detects a pre-pit signal only at a correct position where a signal should appear, and prevents erroneous detection even when a noise component is superimposed on a wobbling signal (for example, see Japanese Patent Application Laid-Open No. H10-340536).

[0015]

However, the above-described apparatus has a problem that when a noise component is superimposed on a wobbling signal, information based on a pre-pit signal cannot be obtained accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to enable more accurate information based on a pre-pit signal to be obtained even when a noise component is superimposed on a wobbling signal. I do.

[0017]

According to the present invention, in order to achieve the above object, a data recording track wobbled with a predetermined frequency component and a prepit having a predetermined phase relationship with the data recording track are formed. A pre-pit information detecting device of an optical disc driving device provided with means for detecting information based on said pre-pits when recording information on said optical disc, wherein said wobble component is extracted by extracting only a wobbling component of said data recording track. A wobble signal detecting means for generating a signal; a pre-pit signal detecting means for detecting a pre-pit of the data recording track to generate the pre-pit signal; and determining a pre-pit pattern from the pre-pit signal by a first predetermined pattern length. Detects the synchronization signal based on the determination result, and A synchronization signal detecting means for outputting,
Prepit data detection means for judging a prepit pattern from the prepit signal with a second predetermined pattern length, detecting prepit data based on the judgment result, and outputting the prepit data signal; And a synchronization state determining means for outputting a synchronization state determination signal based on the determination result, a cycle corresponding to the cycle of the wobbling signal as a count change cycle, and a generation cycle of the pre-pit signal as a full count cycle. Counting means for measuring elapsed time by self-running, and decoding a count value measured by the counting means, and outputting an enable signal for enabling output of the synchronization detection signal and the pre-pit signal based on a predetermined count value. Decoding means, the first predetermined pattern length and the second A constant pattern length is one that was set to a different pattern lengths, respectively.

In the above-described pre-pit information detecting device for an optical disk drive, it is preferable that the second predetermined pattern length is shorter than a predetermined pattern position on a fobble cycle in which the pre-pits are formed.

Further, in the above-described pre-pit information detecting device for an optical disk drive, it is preferable that the first predetermined pattern length is longer than a predetermined pattern position on a wobble cycle in which the pre-pits are formed.

In the above-described pre-pit information detecting device for an optical disk drive, the synchronous signal detecting means may determine whether or not the synchronous state is determined by the synchronous state determining means.
It is preferable to provide means for determining the pre-pit pattern based on a third predetermined pattern length different from the first predetermined pattern length when the synchronization is in a synchronized state.

Further, in the above-described pre-pit information detecting device for an optical disk drive, it is preferable that the third predetermined pattern length is shorter than a predetermined pattern position on a wobble cycle in which the pre-pits are formed.

[0022]

Embodiments of the present invention will be specifically described below with reference to the drawings. First, a pre-pit corresponding to the pre-information as the recording control information is formed, and a groove track, which will be described later, is wobbled at a predetermined frequency to record a DV as a recording medium on which rotation control information is recorded.
An embodiment of a DR disk will be described, for example, using a known technique described in Japanese Patent Application Laid-Open No. H10-340536.

First, the DVD of this embodiment will be described with reference to FIG.
The structure of the -R disc will be described. As shown in FIG. 1, the DVD-R disk 1 is a dye-type DVD-R disk having a dye film 5 and capable of writing information only once, and includes a groove track 2 as an information track and the groove track 2. A land track 3 is formed as an adjacent track for guiding a light beam B such as a laser beam as a reproduction light or a recording light.

Further, a protective film 7 for protecting them and a gold vapor-deposited surface 6 for reflecting the light beam B when reproducing recorded information are provided. Further, pre-pits 4 corresponding to the pre-information are formed on the land tracks 3. The pre-pits 4 are formed before the DVD-R disc 1 is shipped.

In the DVD-R disc 1, the groove tracks 2 are wobbled at a frequency corresponding to the rotation speed of the DVD-R disc 1. The recording of the rotation control information by the wobbling of the groove track 2 is executed in advance before the DVD-R disc 1 is shipped, like the pre-pit 4.

When recording information (this is information such as image information to be originally recorded other than pre-information and rotation control information, and the same applies to the following) on the DVD-R disc 1, In an information recording apparatus according to an embodiment of the present invention described later, rotation control information is acquired by detecting the wobbling frequency of
By controlling the rotation of the VD-R disc 1 at a predetermined rotation speed and detecting the pre-pits 4, pre-information is obtained in advance, and the optimum output of the light beam B as the recording light is set based on the pre-information. At the same time, address information or the like, which is a position on the DVD-R disc 1 where the recording information is to be recorded, is obtained, and the recording information is recorded at the corresponding recording position based on the address information.

Here, at the time of recording the recording information, a light beam B is irradiated so that the center thereof coincides with the center of the groove track 2 to form a recording information pit corresponding to the recording information on the groove track 2. Thus, recording information is formed. At this time, the size of the light spot SP is set so that a part thereof is irradiated not only on the groove track 2 but also on the land track 3 as shown in FIG.

The light detector SP divided by a division line parallel to the rotation direction of the DVD-R disc 1 using the push-pull method by using a part of the reflected light of the light spot SP applied to the land track 3 is used. By using the push-pull method (hereinafter referred to as “radial push-pull method”), pre-information is detected from the pre-pits 4 and the pre-information is obtained, and the reflected light of the light spot SP applied to the groove track 2 The wobbling signal is detected from the groove track 2 by using the reflected light of the light spot SP applied to the groove track 2 by using the above, and a clock signal for rotation control is obtained.

Next, a recording format of pre-information and rotation control information pre-recorded on the DVD-R disc 1 of this embodiment will be described with reference to FIGS. 2A and 2B.

FIG. 2A shows a signal of a portion from which a pre-pit signal can be obtained among signals obtained when recorded information is reproduced.
FIG. 2B shows the entire signal when the recorded information is reproduced.

The waveform of the wobbling signal shown in FIGS. 2A and 2B has a shape reflecting the wobbling state of the groove track 2 for recording the recording information. Further, as shown in FIGS. 2A and 2B, in this embodiment, the recording information recorded on the DVD-R disc 1 is divided in advance into sync frames as information units.

Then, 1 is determined by 26 sync frames.
One recording sector, and one ECC (Error) by 16 recording sectors.
(Correcting code) block.

One sync frame has a length of 1488 times (1448T) a unit length (hereinafter referred to as "T") corresponding to a bit interval defined by a recording format for recording the recording information. have.

The groove track 2 has a frequency of 145 kHz (one sync frame corresponds to 8
Constant wobbling frequency f0)
Wobbling at. Then, in the information recording apparatus of this embodiment described later, a signal for controlling the rotation of the spindle motor is detected by detecting the constant wobbling frequency: f0.

On the other hand, in this embodiment, the pre-information recorded on the DVD-R disc 1 is recorded for each sync frame. Here, in the recording of the pre-information by the pre-pits 4, one pre-pit 4 is always required to indicate the synchronizing signal in the pre-information on the land track 3 adjacent to the area where the synchronizing information in each sync frame in the recording information is recorded. Are formed, and two or one pre-pit 4 is formed to indicate the content (address information) of the pre-information to be recorded on the land track 3 adjacent to the first half of the sync frame other than the synchronization information. I do.

In the first half of the sync frame other than the synchronization information, the pre-pit 4 may not be formed depending on the contents of the pre-information to be recorded. In one recording sector, only even-numbered sync frames (hereinafter, referred to as “EVEN frames”) or odd-numbered sync frames (hereinafter, referred to as “OD frames”) are used.
In some cases, pre-pits 4 are formed only in the “D frame” and pre-information is recorded.

The reproduced signal of the pre-pit 4 formed in this manner is superimposed on the wobbling signal as shown in FIGS. 2A and 2B. Usually, the pre-pit signal is included in the EVEN sync frame. appear.

However, when the pre-pits 4 are adjacent to each other, crosstalk occurs between the pre-pit signals. Therefore, as shown by the dotted line in FIG.
To form

Conversely, from the ODD sync frame to the EV
The pre-pit 4 may be moved to the EN sync frame. Also, as shown in FIG. 2A, the pre-pit signal includes b0, b1, and b1 in eight cycles of the wobbling signal.
It occurs at three places indicated by b2. The pre-pit signal has the following meaning depending on the position of occurrence.

FIGS. 3A and 3B are diagrams for explaining the meaning of the pre-pit signal. FIG. 3A shows the relationship between the wobbling signal and the pre-pit signal, and FIG. FIG. 3C is a diagram showing an expected position of a pre-pit signal, and FIG. 3C is a diagram showing a break of wobbling every eight cycles.

FIG. 3D is a diagram showing an example of the generation position of the pre-pit signal when the pre-pit does not move between the EVEN sync frame and the ODD sync frame.
FIG. 3E is a diagram showing an example of a pre-pit signal generation device when the above-mentioned movement is performed.

In FIGS. 3B, 3D and 3E, the positions indicated by triangles are the positions of the prepit signals generated in the ODD sync frame, and the positions indicated by the squares are the prepits generated in the EVEN sync frame. The position of the signal is shown.

As shown in FIGS. 3B and 3C, the pre-pit signal occurs in the first three cycles of the eight cycles of the wobbling signal in any of the sync frames, and occurs in the remaining five cycles. There is no case.

As can be seen from FIGS. 3D and 3E, the pre-pit signal at the position b0 appears in each sync frame. Therefore, the value of the pre-pit signal is always "1" and functions as a sync bit for synchronizing the detection of the pre-pit signal.

The pre-pit signal at the position b1 appears only in the first sync frame. Further, the value of the pre-pit signal is always "1". When the pre-pit signal does not appear at the position b1, data such as an address is indicated by the pre-pit signal at the next position b2.

When the pre-pit signal appears at the position b1, the pre-pit signal at the position b2 becomes a signal indicating the EVEN sync frame or the ODD sync frame.

That is, as shown in (D) and (E) of FIG. 3, when the pre-pit signal appears at the positions b1 and b2, it is determined that the pre-pit signal is the head frame of the EVEN sync frame. When the pre-pit signal appears at the position b1 and the pre-pit signal does not appear at the position b2, it can be determined that the frame is the first frame of the ODD sync frame.

When the pre-pit signal does not appear at the position b1, the data value is indicated by the pre-pit signal. When the pre-pit signal appears at the position b2, the value of "1" is set. If the pre-pit signal does not appear at the position b2, the value indicates "0".

For example, in the examples shown in FIGS. 3D and 3E, the data of BIT1 becomes "1" and the data of BIT2 becomes "0".

As described above, one sector is composed of the first sync frame (indicated as “LPP SYNC” in FIG. 3) and the BIT
It is composed of data sync frames from 1 to BIT12. As described above, by decoding the pre-pit signal, sync information or data information can be obtained.

Table 1 shows the result of decoding the pre-pit signal.

[0052]

[Table 1]

Conventionally, the decoding of the pre-pit signal as described above has been performed by a circuit as shown in FIG. The pre-pit signal decoder shown in FIG. 4 extracts the pre-pit signal from the reproduction signal and binarizes it.
It comprises a digitizing circuit 100 and a wobbling signal binarizing circuit 101 for extracting a wobbling signal from a reproduced signal and binarizing the same.

The binarized pre-pit signal output from the LPP binarization circuit 100 (hereinafter referred to as "binarized LPP")
), The rising edges of the binarized wobbling signal output from the wobbling binarization circuit 101 are input to the synchronization flip-flop 102, and 1 is set to the data input of the flip-flop 102. Thus, the signals are sequentially latched by the shift register 103 at the appearance timing of the pre-pit signal.

The latched data includes a reference sync pattern previously created based on the decoding result of Table 1 and stored in the reference sync pattern generation circuit 105;
The data is compared in the comparator 104, and when they match, the information is obtained as sync information or data information.

FIG. 5 is a diagram showing a decoding example using the decoder shown in FIG. Note that in FIG.
The signal indicated by f is the signal at the position indicated by the same reference numeral in FIG.

Since the Q output of the flip-flop 102 is reset every T1 which is the period of the wobbling signal, 0 is latched in the shift register 103 when the pre-pit signal does not appear.

Then, when the pre-pit signal appears at times: t1 and t2, the Q output of the flip-flop 102 becomes "1", and the "1" becomes the shift register 103.
Latched. Then, a detection pulse is output from the comparator 104 in the twelfth cycle from the sync bit.

In the example shown in FIG. 5, the information "110" is decoded, and it can be determined that the current frame is the first frame of the ODD sync frame.

Conventionally, pre-information is obtained from a pre-pit signal in this way. However, when crosstalk occurs from other pre-pits 4 formed on the DVD-R disc 1 or when dust or dirt adheres to the DVD-R disc 1, as shown in FIG. In some cases, a noise component was superimposed on the wobbling signal.

Since the noise component may be detected as a pre-pit signal in the circuit shown in FIG. 4, an erroneous detection pulse is output at time t6 as shown in FIG. There is a problem that the detection pulse is not output at the position indicated by the dotted circle where the pulse is to be output. As a result, a correct sync phase and correct data cannot be obtained, and the recording apparatus may not operate normally.

Next, a process of detecting a pre-pit signal in the information recording apparatus according to one embodiment of the present invention will be described. FIG. 7 is a diagram showing a configuration of an information recording device which is an embodiment of the pre-pit information detecting device of the optical disk drive of the present invention.

This information recording apparatus is realized by a microcomputer including a CPU, a ROM, a RAM, and the like. When recording digital information transmitted from a host computer on the DVD-R disc 1, the present invention is applicable to the present invention. The detection processing of such a pre-pit signal is executed.

The DVD-R disc 1 contains the DVD-R
The pre-pit 4 including the address information on the R disk 1 and the groove track 2 to be wobbled are formed in advance. When recording the digital information, the pre-pit 4 is detected in advance, so that the address information on the DVD-R disk 1 is detected. The recording position on the DVD-R disc 1 for recording digital information is detected and recorded.

As shown in FIG. 7, the information recording apparatus S of this embodiment includes a pickup 10, a reproducing amplifier 11,
Decoder 12, CPU 13, pre-pit signal encoder 14, power control circuit 15, laser drive circuit 1,
6, a pre-pit signal decoder 18, a pre-pit signal detector 19, a pre-pit signal decoding timing signal generator 20, and a BPF (Band Pass Fil).
ter) 21.

Further, a wobbling signal detector 22, a wobbling signal phase comparator 23, a pre-pit signal phase comparator 24, a spindle driver 25, a spindle motor 26, a switch 27, and a VCO (Voltag)
eControlledOscillator) 28
, A reference clock generator 29, a spindle phase comparator 30, and frequency dividers 31 and 32.

Digital information Srr to be recorded from an external host computer is input to the information recording device S via the interface 17.

Next, the overall operation of the information recording apparatus S will be described. The pickup 10 includes a laser diode, a polarizing beam splitter, an objective lens, a photodetector, and the like (not shown), a laser beam, and a drive signal: Sd.
1 to irradiate the information recording surface of the DVD-R disc 1 with the light beam B, and detect the wobbling signal of the pre-pit 4 and the groove track 2 by the radial push-pull method based on the reflected light to record the digital data. Information: Srr is recorded, and if there is already recorded digital information, the already recorded digital information is detected based on the reflected light of the light beam B.

The reproduction amplifier 11 amplifies the pickup detection signal: Sdt containing information corresponding to the pre-pit 4 and the wobbling signal of the groove track 2 output from the pickup 10, and converts the signal into a wobbling signal of the pre-pit 4 and the groove track 2. A corresponding pre-information signal: Spp is output, and an amplified signal: Sp corresponding to already recorded digital information is output.

Thereafter, the decoder 12 outputs the amplified signal: Sp
Is subjected to 8-16 demodulation and deinterleaving, thereby decoding the amplified signal: Sp and demodulating the signal:
Sdm is output to the CPU 13.

On the other hand, the pre-pit signal detector 19 outputs a pulse signal as a pre-pit detection signal: Spd to the pre-pit signal phase comparator 24 and the pre-pit signal latch circuit 40 by a process described later based on the pre-information signal: Spp.

The pre-pit signal latch latches a pre-pit detection signal: Spd by a process described later, and outputs it to the pre-pit signal decoder 18 and the pre-pit signal decoding timing signal generator 20.

Further, the wobbling signal detector 22
The wobbling signal component extracted from the pre-information signal: Spp by the PF 21 is input, the input wobbling signal component is compared with a predetermined reference value by an internal comparator, and the amplitude level of the wobbling signal component is higher than the reference value. The pulse signal is output only during the period when the pulse signal is large.

That is, the wobbling signal component is converted into a pulse train, and a binarized wobbling signal: Swb,
Output to the wobbling phase comparator 23.

The wobbling phase comparator 23,
Prepit phase comparator 24, switch 27, VCO2
8 and the frequency divider 32 constitute a so-called PLL circuit, and the input binarized wobbling signal: Sw
A clock for recording: VCK synchronized with b is generated, and when synchronization is achieved, the switch 27 is switched to provide a more accurate recording clock signal than the one synchronized with the phase of the input pre-pit detection signal: Spd. : VCK is converted to a pre-pit signal decoding timing signal generator 20, a pre-pit signal encoder 14, and a pre-pit signal detector 1.
9 respectively.

On the other hand, the recording clock signal: VCK
Is input to the spindle phase comparator 30 via the two frequency dividers 32 and 31, and the spindle phase comparator 30
Performs a phase comparison between the input signal and a reference clock signal Sref including a reference frequency component of the rotation speed of the DVD-R disc 1 supplied from the reference clock generator 29, and uses the difference signal as a rotation control signal. It is supplied to a spindle motor 26 via a spindle driver 25.

Thus, the spindle servo control is performed on the spindle motor 26, and the DVD-R disc 1 rotates at a rotation speed based on the frequency and phase of the reference clock signal: Sref.

The interface 17 is connected to the CPU 1
The digital information Srr transmitted from the host computer under the control of Step 3 performs an interface operation for taking the digital information Srr into the information recording device S, and the digital information Srr after the interface processing is transmitted to the CPU 13. To the encoder 14 via the.

In this way, the encoder 14 uses the encoding synchronizing signal: Scr from the pre-pit signal decoding timing signal generator 20 as a timing signal,
The modulation signal: Sre is generated by performing C generation processing, 8-16 modulation, and scrambling processing, and is output to the power control circuit 15.

After that, the power control circuit 15
In order to improve the shape of the recording pits formed on the R disk 1, a waveform conversion (corresponding to a so-called "write strategy process") of a modulation signal: Sre is performed based on the recording clock signal: VCK, and pickup is performed. A recording signal for driving a laser diode (not shown) in 10 is output as Sd.

Further, the laser drive circuit 16 outputs a recording signal:
The laser drive signal for actually driving the laser diode to emit the light beam B based on Sd:
Sd1 is output.

Finally, the CPU 13 executes the pre-decoding based on the pre-information decoding signal: Spj output from the pre-pit signal decoder 18 based on the decode timing signal: WB3GATE output from the pre-pit signal decoding timing signal generator 20. Information corresponding to the address information included in the pre-information.
The operation of recording digital information: Srr at a position on the DR disk 1 is controlled.

In parallel with this control operation, the CPU 13
Based on the demodulated signal: Sdm, a reproduction signal corresponding to the digital information already recorded is output to the outside via the interface 17 and the overall operation of the information recording device S is controlled.

FIG. 8 is a diagram showing the configuration of the pre-pit signal latch circuit 40, and FIG. 9 is a diagram showing the operation timing of the pre-pit signal latch circuit 40. As shown in FIG. 8, in the pre-pit signal latch circuit 40, in addition to the above-mentioned pre-pit detection signal: Spd, the fVWB signal, and the LPPGAT
E signals are input respectively.

The fVWB signal is generated by a PL comprising a wobbling signal phase comparator 23, a VCO 28 and a frequency divider 32.
This is a signal provided with a phase with the above-mentioned binarized wobbling signal: Swb by the L circuit, and a recording clock: VC
This is a signal generated by dividing K.

The LPPGATE signal is a signal indicating a period in which the prepit signal is estimated to appear superimposed on the wobbling signal. The LPPGATE signal is turned on (ON) after a predetermined period from the fall of the fVWB signal. After a period, it is turned off.

In the gate generating circuit or another circuit described later, only the pre-pit signal detected when the LPPGATE signal is in the ON state is employed to detect or decode the presence or absence of the pre-pit signal.

Therefore, even if noise having an output level value equivalent to the pre-pit signal occurs at the timing when the pre-pit signal cannot appear, the noise is not erroneously detected as the pre-pit signal. The above LPPGAT
The E signal is input to an AND gate together with a pre-pit detection signal: Spd.

Therefore, as shown in FIG.
When the binarized LPP signal is output while the E signal is in the ON state, the output of the AND gate becomes “1”, and the output of the AND gate becomes S.
Since it is input to the set terminal of the R flip-flop, S
The output Qa of the R flip-flop is turned on. The reset terminal R of the SR flip-flop has fVWB
A signal is input. Therefore, the SR flip-flop is reset at the falling portion of the fVWB signal,
The output Qa of the flip-flop is turned off.

The D flip-flop operates in synchronization with the falling edge of the fVWB signal. Therefore, D
The LPPSET signal which is the output of the flip-flop is S
The next fV at which the output Qa of the R flip-flop is turned on
It is turned ON for the falling period of the WB signal.

As described above, the LPPSET signal is a signal indicating that the pre-pit signal has appeared, and the fVW
It is created so as to have one cycle width of the B signal.

FIG. 10 is a diagram showing the structure of the pre-pit signal decoding timing signal generator 20, and FIGS.
3 is a diagram showing the operation timing of the pre-pit signal decoding timing signal generator 20, respectively. For the sake of convenience in the following description, a pair of an EVEN sync frame and an ODD sync frame is defined as one unit, and is referred to as a pre-pit data frame.

One pre-pit data frame corresponds to 16 cycles of the wobbling signal. One pre-pit frame is numbered sequentially from the top in the cycle of the wobbling signal, and is called wobbling cycles 0 to 15.

As shown in FIG. 10, the LPPSET signal is input to a shift register 200 that operates using the fVWB signal as a clock. The data in the shift register is
.. Q12 in the order of Q0, Q1,... The pattern match circuit 201 decodes the output of the shift register and generates a synchronization detection signal according to a truth table shown in Table 2.
Outputs SNC1.

[0095]

[Table 2]

In other words, the truth table in Table 2 indicates that the pre-pit signal pattern of 1, 1, 0 was present in the three cycles immediately before the wobbling cycle, or the three cycles immediately before the point eight cycles from the wobbling cycle. FIG. 9 is a table showing changes in which SNC1 is turned on when there is a pre-pit signal pattern of 1, 1, 1 in FIG.

Here, in other words, referring to the decoding table of the pre-pit signal in Table 1 above, in other words, SNC1
Is turned on, the wobbling cycle is the wobbling cycle 11 in the pre-pit data frame including the head ODD sync frame, or the wobbling cycle is the pre-pit including the head EVEN sync frame. This is the wobbling cycle 11 in the data frame.

The state machine 204 determines the synchronization state of the pre-pit signal decoding timing signal generator. In the initial state, the synchronization state determined by the state machine 204 is an asynchronous state. In the asynchronous state, the state machine 204 outputs the synchronous state detection signal LOC.
K is in the OFF state.

The state machine 204 has a LOCK
Is OFF, the detection of the SNC 1 is waited. When the SNC 1 is detected, a LOAD signal is output to the flywheel counter 205 in the wobbling cycle. Further, the synchronization state is determined to be the synchronization state, and the synchronization state detection signal L is output from the next wobbling cycle.
Turn OCK ON.

The flywheel counter 205 is a counter that indicates a wobbling cycle in one pre-pit data frame. The flywheel counter 20
When the LOAD signal is input to 5, the count value is set to "12" in the next wobbling cycle.

As described above, the SNC1 is turned ON in the wobbling cycle 11, and when the SNC1 is detected in an asynchronous state, the LOAD signal is input. Therefore, the count value of the flywheel counter 205 is changed from the next fobbling cycle. This will match the wobbling cycle number.

In this way, the initial synchronization detection of pre-pit signal decoding timing signal generator 20 is performed.

FIG. 11A shows the pattern match circuit 201, the state machine 204, and the flywheel counter 20 when the leading EVEN sync frame is detected.
FIG. 11B shows the operation timing at the time of detecting the initial synchronization of the pattern match circuit 201, the state machine 204, and the flywheel counter 205 when the leading EVEN sync frame is detected. FIG.

As shown in FIG. 11A, the edge detection circuit 207 detects a rising edge of the fVWB signal. The count value of the counter 208 that counts with the recording clock signal: VCK is cleared every time a rising edge of the fVWB signal is detected.

The decoder 209 decodes the count value of the counter 208 and generates the above-described LPPGATE signal which is turned on after a predetermined period from the fall of the fVWB signal and turned off after a predetermined period. Decoder 2
06 decodes the count value of the flywheel counter 205 and decodes the signal CYC with a specific count value.
L0 + 8 and CYCL3 + 11 are generated.

The decode signal: CYCL0 + 8 is a signal output when the count value is "0" or "8". Since the count value of the flywheel counter 205 matches the number of the wobbling cycle in the synchronized state, the decode signal: CYCL0 + 8 becomes “1” in the first wobbling cycle of the EVEN sync frame and the ODD sync frame.

Decode signals: CYCL0 + 8 and LPPG
The ATE signal is input to the AND circuit, and the PCGATE signal is output. The PCGATE signal operates a pre-pit signal phase comparator, which will be described later, only while the signal is in the ON state.

The CYCL11 signal has a count value of “1”.
1 ". Since the count value of the flywheel counter 205 coincides with the number of the wobbling cycle in the synchronous state, the CYCL11 signal indicates the wobbling cycle 11, that is, the b0 position of the ODD sync frame. O in the next wobbling cycle
It becomes N.

The pattern match circuit 203 decodes the output of the shift register and outputs the LPPDAT signal and the DATAN signal according to the truth table shown in Table 3.

[0110]

[Table 3]

The LPPDAT signal is output to the pre-pit signal decoder 18. Further, the DATAN signal is ANDed with the CYCL11 signal indicating the wobbling cycle 11, and is output to the pre-pit signal decoder 18 as a DATGATE signal.

The pre-pit signal decoder 18 has a DATG
Only when the ATE signal is "1", the LPPDAT signal and the DATAN signal are checked, and the data of the pre-pit is decoded. When the DATGATE signal is monitored only in the wobbling cycle 11, Q9 and Q8 are EVEN
Q1 and Q0 correspond to the pre-pit signals of b1 and b2 of the ODD sync frame, corresponding to the pre-pit signals of b1 and b2 of the sync frame.

Therefore, when the DATEN signal is monitored only in the wobbling cycle 11, there is a pattern of "1" of the pre-pit signal at the position b1 of the ODD sync frame, or a pattern of the pre-pit signal at the position b1 of the EVEN sync frame. If there is, DA
The TGATE signal is turned off.

In other words, when the DATGATE signal is monitored only in the wobbling cycle 11, OD
When the first sync frame is detected in the D sync frame or the EVEN sync frame, the state is OFF, and otherwise the state is ON.

Therefore, the DATEN signal and CYCL1
The DATGATE signal obtained by ANDing one signal is turned ON only in the wobbling cycle 11 of the pre-pit data frame other than the head sync frame.

When the LPPDAT signal is monitored only in the wobbling cycle 11, there is a pattern of the pre-pit signal "1" at the position b2 of the ODD sync frame, or "1" of the pre-pit signal at the position b2 of the EVEN sync frame. If there is a pattern of LP
The PDAT signal becomes "1".

The pre-pit decoder 18 has a DATGAT
The LPPDAT signal is detected only at the timing when the E signal is "1", and the pre-pit data is decoded.

FIGS. 12 and 13 show the pattern match circuit 2
03, flywheel counter 205, decoder 20
FIG. 6 is a diagram showing operation timings of the AND gate and the AND gate.

FIG. 12A shows the operation timing when b0, b1, and b2 are data 1 patterns.
(B) shows the operation timing in the case of the data 0 pattern. LPPDAT at DATGATE output
Are decoded values.

FIG. 13C shows the operation timing when b0, b1 and b2 are the patterns of the head EVEN frame sync, and FIG. 13D shows the operation timing when the pattern of the head ODD frame sync is used. ing.

In these patterns, DATGA
No TE signal is output. According to the decoding table shown in Table 1, the pre-pit data is decoded from three bits b0, b1, and b2.

In the above example, three bits b0, b1 and b2 are used for detecting the first sync frame, whereas the pre-pit data is decoded from the two bits b1 and b2.

The reason why decoding is possible with these two bits is that the wobbling cycle position is known by the operation of the flywheel counter in the synchronized state of the information recording device S, and the pre-pit signal of the sync frame b0 is referred to. This is because there is no need.

If the number of bits to be referred to for the decoder is reduced, the probability that the range of bits to be referred to contains an error is reduced, and decoding errors can be reduced. Therefore, the detection reliability of the pre-pit data can be improved.
And Embodiment 2).

Next, another embodiment of the present invention will be described. The information recording apparatus S of this embodiment performs a decoding process different from that of the pattern matching circuit 201 of the information recording apparatus S described above. That is, only the decoding table described above is different. The pattern match circuit 201 of this information recording device S decodes the shift register output and
And outputs a synchronization detection signal: SNC1 in accordance with the truth table shown in FIG.

[0126]

[Table 4]

In other words, the truth table in Table 4 indicates that the pre-pit signal pattern of 0, 1, 1, 0 was present in the four cycles immediately before the wobbling cycle, or that the four bits immediately before the point eight cycles back from the wobbling cycle. 9 is a table showing that SNC1 is turned on when a prepit signal pattern of 0, 1, 1, 1 is present in a cycle.

Since the pre-pit signal is originally “0” at positions other than the b0, 1, and 2 positions, the pre-pit signal is compared with the pre-pit signal decoding table shown in Table 1 above.
When CN1 is turned on, the wobbling cycle is the wobbling cycle 11 of the pre-pit data frame including the leading ODD sync frame, or
Alternatively, the wobbling cycle is the wobbling cycle 11 of the pre-pit data frame including the leading EVEN sync frame. This is the same as the description based on Table 2 above.

FIG. 14 is a diagram showing operation timings which differ from the truth table of Table 2 when the truth table of Table 4 is used. The pre-pit data frame shown in FIG. 14 includes a leading EVEN sync frame. Therefore, a pre-pit signal exists in b0, 1, 2 (wobbling cycle 0, 1, 2) of the EVEN sync frame.

In the wobbling cycle 11, the data in the shift register 200 is (Q12, Q11, Q1).
0, Q9, Q8, Q7. . . ) = (0,0,1,1,
1,0. . . ), The condition that the SNC1 is turned ON is satisfied by using any of the truth tables in Tables 2 and 4.

Next, an operation in another wobbling cycle 4 will be considered. Wobbling cycle 4
In, the data of the shift register 200 is (...
W4, Q3, Q2, Q1, Q0) = (... 0, 1,
1,1,0). According to the truth table in Table 2, this pattern corresponds to the condition that SCN1 is turned on.

On the other hand, according to the truth table in Table 4, the SN
The condition that C1 is turned on does not apply.

That is, in the asynchronous state, in the case of the pattern match circuit 201 using the truth table of Table 2, SNC1 is output in the wobbling cycle 4 of the pre-pit data frame including the leading EVEN sync frame. As a result, the LOAD signal may be output to the above-described flywheel counter 205, and the count value may be set to 12 in the next wobbling cycle 5.

In this case, the count value of the flywheel counter does not match the wobbling cycle number.

Of course, even in this case, since the initial synchronization is detected again by detecting the asynchronous state described later, a correct synchronous state is eventually obtained, but it takes time to establish the synchronization.

However, in the case of using the truth table of Table 4 described above, since there is no such erroneous synchronization detection at the time of initial synchronization detection, synchronization is quickly established (this is the third aspect of the present invention). This corresponds to the effect of the first embodiment).

FIG. 15 is a diagram showing the operation timing of the pre-pit signal decoding timing signal generator 20 when the synchronization is lost for some reason in the synchronized state.

There are several factors that cause the loss of synchronization. For example, a wobbling signal or a pre-pit signal is lost due to a defect existing on the DVD-R disc 1 or the like, and a PLL circuit causes a lock deviation, and the fVWB and the wobbling signal are lost. There are cases where the phase relationship has shifted.

Therefore, the processing of the pattern match circuit 202 shown in FIG. 10 is made different, the output of the shift register is decoded, and the synchronization detection signal S is obtained according to the truth table shown in Table 5.
It is preferable to output NC2.

[0140]

[Table 5]

When the SNC2 is monitored only in the wobbling cycle 11, there is a pattern of 1 of the pre-pit signal at the position of b0 in the ODD sync frame, or
When there is a pattern of “1” of the pre-pit signal at the position of b0 in the VEN sync frame, SNC2 becomes “1”.

In the synchronous state, the state machine 204 refers to the CYCL11 signal input from the decoder 206 and the SNC2 signal input from the pattern match circuit 201, and determines when the CYCL11 signal is "1" (vobbing cycle 11). Outputs different signals depending on whether or not SNC2 is "1".

If the SNC2 is "1" in the wobbling cycle 11, it means that the pattern of the prepit signal b0 is detected at the position where the count value of the flywheel counter 205 is "0" or "8". The count value of the flywheel counter matches the wobbling cycle number, and it can be determined that the flywheel counter is in a synchronized state.

When the SNC2 is "0" in the wobbling cycle 11, the count value of the flywheel counter may not match the wobbling cycle number. However, there is a case where the pre-pit signal is defective and the SNC2 signal is not detected even in the synchronized state. Therefore, in this information recording apparatus S, if the SNC2 signal cannot be continuously detected in the wobbling cycle 11 as described below. Is determined to be in an asynchronous state.

First, in the wobbling cycle 11, the SNC
When 2 is “1”, the state machine 204 outputs a clear signal: CLR to the error counter 210. When SNC2 is 1 in the wobbling cycle 11,
The state machine 204 outputs a count-up signal UP to the error counter 210.

The decoder 211 includes an error counter 210
Is decoded, and when the count value reaches "3", an error signal: SNCERR is output.

In FIG. 15, the PLL circuit causes a lock deviation in the pre-pit data frame indicated by # 4, and the wobbling cycle 1 of the pre-pit data frame after # 5.
1 shows operation timings of the pattern match circuit 202, the state machine 204, the error counter 210, and the decoder 211 when the SNC 2 is continuously undetected.

In the information recording apparatus S in this case, the pattern match circuit 201 for detecting the synchronization pattern used for the initial synchronization operation and the pattern match circuit 202 for detecting the synchronization pattern used for the out-of-synchronization detection operation include: The reference bit position and the number of bits are different.

When the truth table of Table 4 is applied by the pattern match circuit 201 and the truth table of Table 5 is applied by the pattern match circuit 202, the number of bits referred to in the initial synchronization operation is “4”. On the other hand, the number of bits referred to in the out-of-synchronization operation is “3”. Then, when the number of bits to be referred to is small, the probability that an error is included in the bit range to be referred to decreases.

Thus, the probability that the SNC 2 is not detected due to a defect in the pre-pit signal is reduced even in the synchronized state, and the probability of erroneously determining that synchronization has been lost can be reduced. Therefore, it is possible to improve the detection reliability of the pre-pit data (this corresponds to the effect of the fourth and fifth embodiments of the present invention).

[0151]

As described above, in the pre-pit information detecting device of the optical disk drive according to the first and second aspects of the present invention, in the initial synchronization operation, the pre-pit signal at only a specific position in the eight periods of the wobbling signal is used. Since the synchronization is detected with reference to the reference position, even if there is a defect at a position other than the specific position to be referred to, an erroneous synchronization detection is not performed. In decoding the pre-pit data, a pre-pit signal at only a specific position smaller than a predetermined pattern position on a wobble cycle in which the pre-pit is formed is referred to, so that decoding errors can be reduced. Therefore, the detection reliability of the pre-pit data can be improved.

In the pre-pit information detecting device of the optical disk drive according to the third aspect of the present invention, in the initial synchronization operation, the synchronization is detected by referring to a pre-pit signal longer than a predetermined pattern position on a wobble cycle in which the pre-pit is formed. As a result, erroneous synchronization detection at the time of initial synchronization detection is eliminated, and synchronization can be quickly established.

Further, in the pre-pit information detecting device of the optical disk drive according to the fourth and fifth aspects of the present invention, the out-of-synchronization detection is performed by referring to a pre-pit signal only at a specific position shorter than the initial synchronization operation. Therefore, even in the synchronized state, it is possible to reduce the probability of erroneously determining out-of-synchronization due to a defect in the pre-pit signal.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a structure of a DVD-R disc used by an information recording device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a recording format of pre-information and rotation control information recorded in advance on a DVD-R disc used by the information recording apparatus of the embodiment of the present invention.

FIG. 3 is a diagram for explaining the meaning of a pre-pit signal.

FIG. 4 is a block diagram showing a configuration of a well-known decoder circuit that decodes a pre-pit signal.

FIG. 5 is a diagram illustrating a decoding example using the decoder circuit illustrated in FIG. 4;

FIG. 6 is an explanatory diagram when a noise component is superimposed on a wobbling signal.

FIG. 7 is a diagram showing a configuration of an information recording device which is an embodiment of a pre-pit information detecting device of the optical disk drive of the present invention.

8 is a diagram showing a configuration of a pre-pit signal latch circuit shown in FIG. 7;

9 is a diagram showing operation timings of the pre-pit signal latch circuit shown in FIG.

FIG. 10 is a diagram showing a configuration of a timing signal generator for pre-pit signal decoding shown in FIG. 7;

11 is a diagram showing operation timings of the pre-pit signal decoding timing signal generator shown in FIG. 10;

FIG. 12 is a diagram showing an operation timing of a timing signal generator for decoding a pre-pit signal.

FIG. 13 is a diagram showing an operation timing of a timing signal generator for decoding a pre-pit signal.

FIG. 14 is a diagram showing operation timings that differ from the truth table of Table 2 when the truth table of Table 4 is used in the timing signal generator for decoding a pre-pit signal.

FIG. 15 is a diagram showing the operation timing of the pre-pit signal decoding timing signal generator when synchronization is lost for some reason in the synchronization state.

[Explanation of symbols]

 1: DVD-R disc 2: groove track 3: land track 4: pre-pit 5: dye film 6: gold deposition surface 7: protective film 10: pickup 11: reproduction amplifier 12: decoder 13: CPU 14: pre-pit signal encoder 15: Power control circuit 16: Laser drive circuit 17: Interface 18: Prepit signal decoder 19: Prepit signal detector 20: Prepit signal decoding timing signal generator 21: BPF 22: Wobbling signal detector 23: Wobbling signal phase comparator 24: Prepit signal phase comparator 25: spindle driver 26: spindle motor 27: switch 28: VCO 29: reference clock generator 30: spindle phase comparator 31, 32: frequency divider 40: prepit signal latch circuit 100: L P binarization circuit 101: wobbling signal binarization circuit 102: flip-flop (F / F) circuit for synchronization 103: shift register 104: comparator 105: reference sync pattern generation circuit 200: shift register 201, 202, 203: pattern Match circuit 204: State machine 205: Flywheel counter 206: Decoder 207: Edge detection circuit 208: Counter 209: Decoder

Claims (5)

[Claims] 1. A data recording track wobbled with a predetermined frequency component and a data recording track, wherein information is recorded on an optical disk on which prepits having a predetermined phase relationship are formed. A pre-pit information detection device of an optical disk drive device, comprising: a wobble signal detection unit that extracts only a wobbling component of the data recording track to generate a wobble signal; and the data recording track. A pre-pit signal detecting means for detecting a pre-pit signal and generating a pre-pit signal; determining a pre-pit pattern from the pre-pit signal based on a first predetermined pattern length; detecting a synchronization signal based on the determination result; Synchronization signal detecting means for outputting a detection signal; and the pre-pit signal A pre-pit data detecting means for determining a pre-pit pattern based on a second predetermined pattern length, detecting pre-pit data based on the result of the determination, and outputting the pre-pit data signal; And a synchronization state determination unit that outputs a synchronization state determination signal based on the determination result, and a cycle corresponding to the cycle of the wobbling signal is set as a count change cycle, and the self-running is performed with a generation cycle of the pre-pit signal as a full count cycle. Counting means for measuring the elapsed time by using the decoding means; decoding means for decoding the count value measured by the counting means and outputting an enable signal for enabling the output of the synchronization detection signal and the pre-pit signal based on a predetermined count value The first predetermined pattern length and the second predetermined pattern length Pre-pit information detecting apparatus of an optical disk driving apparatus being characterized in that as Re becomes different pattern lengths respectively. 2. The pre-pit information detecting device for an optical disk drive according to claim 1, wherein the second predetermined pattern length is shorter than a predetermined pattern position on a fobble cycle in which the pre-pits are formed. A pre-pit information detection device for an optical disk drive, characterized by the following. 3. The pre-pit information detecting device for an optical disk drive according to claim 1, wherein the first predetermined pattern length is longer than a predetermined pattern position on a wobble cycle in which the pre-pits are formed. A pre-pit information detection device for an optical disk drive, characterized by the following. 4. The pre-pit information detecting device for an optical disk drive according to claim 1, wherein said synchronous signal detecting means is configured to change the pattern of said pre-pit when the synchronous state determination by said synchronous state determining means is asynchronous. An optical disc drive device comprising means for judging the prepit pattern with a third predetermined pattern length different from the first predetermined pattern length when the synchronization is in a synchronized state. Pre-pit information detection device. 5. The pre-pit information detecting device for an optical disk drive according to claim 4, wherein the third predetermined pattern length is shorter than a predetermined pattern position on a wobble cycle in which the pre-pits are formed. A pre-pit information detection device for an optical disk drive, characterized by the following.