JP3243735B2 - Optical disc playback device - 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 reproducing apparatus suitable for use in a reproducing apparatus for reproducing information recorded on an optical disk.

[0002]

2. Description of the Related Art Recording media for recording by optical modulation include a write-once type (WORM: Write Once Read Many), a rewritable type and a read-only type. These recording media store digital signals supplied at the time of recording by, for example, an optical disc recording device.
The information is recorded by turning on / off the laser beam in accordance with “1” or “0” to form pits, which are uneven recording traces, on the recording medium. The recorded information is reproduced by detecting the return light reflected from the recording medium by the laser light emitted from the optical disc reproducing apparatus.
Utilizing the fact that the reflected light from the pits formed on the recording medium (ie, when it is “1”) is small, and the reflected light from the recording medium where no pits are formed (ie, when it is “0”) is large. ing.

[0003] As described above, the optical disc device controls the built-in optical head by various servos such as a tracking servo and a focus servo in order to perform high-speed access to recording information recorded at a high density to perform recording and / or reproduction. Is going. In order to perform this servo control efficiently, the recording medium employs various methods such as introducing a mirror portion by interrupting a groove serving as a guide groove or adding a wobble pit staggered with respect to a track center. Information is recorded. In order to enable high-speed access, the recording medium records absolute time (Absolute Time In Pregroove: hereinafter referred to as ATIP) information, which is one of the address information, and forms a pre-groove in advance. The aim is to improve the information recording density and simplify the optical disk device.

FIG. 3 shows a part of a pre-groove 31 spirally formed from the innermost side to the outermost side while wobbling. The disc 30 is formed by forming a U-groove or a V-groove in the pre-groove 31 and forming a pit in the pre-groove 31 or in a region between the pre-grooves.
Address information such as the ATIP is recorded in advance by performing M modulation.

[0005]

By detecting the pits formed on the ATIP and the amplitude in the radial direction of the ATIP, the ATIP information can be actually detected. This pit is written in the range of about 200 kHz to 750 kHz.

However, in general, the shape of the pit is not necessarily formed in a direction perpendicular to the radial direction at the amplitude position of the ATIP information because, for example, heating by laser beam irradiation is not performed uniformly. In many cases, the pit shape is affected by deformation.

Further, a photodetector for detecting the return light from the pit outputs, for example, a push-pull error signal from the photodetector. Here, for example, it is known that the push-pull signal which is the difference between the light amounts A and B detected by the two-divided photodetector shown in FIG. However, an asymmetrical pattern is the same as an offset superimposed due to the influence of beam deviation. This is a push-
The fact that the pull error signal becomes essentially zero by canceling the difference AB is a problem caused by the narrow tolerance of the positional deviation F in the positional relationship between the beam and the pit shown in FIG. Further, in the beam image, pit components appear due to the influence of the first-order diffraction of the pit image 40, which is asymmetric with respect to the broken line indicating the boundary between the two photodetectors.

The images 41 and 42 in the beam image are diffraction images from adjacent grooves.

Further, the push-pull error signal is affected by diffraction by the guide groove. The optical disk device servo-controls the optical head unit using the push-pull error signal, but the various effects affect the reading of the ATIP information. As described above, when detecting the ATIP information affected by various effects, the error rate of the signal detected by the photodetector is extremely deteriorated, and the reproducibility is reduced due to a decrease in accuracy. For this reason, the conventional optical disc reproducing apparatus can perform tracking servo control and focus servo control, but the accuracy of servo control is not high. As for the accuracy of the ATIP information, it is difficult to stably obtain a required accuracy.

As described above, the information pits are formed so as to scan over the guide grooves and trace the information. Here, the information actually required by focusing attention is not the information of the pits but the guide grooves. ATIP information written in (groove). Therefore, if only the ATIP information can be read, the accuracy of the read information can be improved.

Therefore, the present invention has been made in view of such circumstances, and extracts only the address information of a stable guide groove, and records pits or pits between recording traces according to the presence or absence of a groove. Absolute time information for the section of
It is an object of the present invention to provide an optical disk reproducing apparatus capable of performing servo control of an optical head unit using one or both of (ATIP).

[0012]

In order to solve the above-mentioned problems, an optical disk reproducing apparatus according to the present invention records a main information signal along a guide groove including a sub-information signal formed in the rotation direction of the optical disk. In an optical disc reproducing apparatus for reproducing an optical disc recorded as a trace, an optical signal detecting means for detecting a signal optically read from the optical disc, and a section between the recording traces of an output signal from the optical signal detecting means. And outputs a sampling signal and masks the output of the sampling signal based on the length of the detected section. A sub-information signal for reproducing the sub-information signal by sampling with the sampling signal output from the inter-trace interval detecting means; It is characterized by having a raw device.

An optical disk reproducing apparatus according to the present invention is an optical disk reproducing apparatus for reproducing an optical disk recorded and formed by displacing a pit string of a main information signal in a radial direction of the disk by a sub information signal. Optical signal detecting means for detecting a signal read in a specific manner, recording trace forming section detecting means for detecting a forming section of each pit in the pit row, and optical means for detecting the section detected by the recording trace forming section detecting means. The above-mentioned object is attained by providing a sub-information signal reproducing means for reproducing the sub-information signal corresponding to the displacement of the pit row in the radial direction of the disk in accordance with the output signal from the target signal detecting means.

Here, the recording trace indicates a pit or a recording area of a rewritable magneto-optical disk. The guide groove is formed by wobbling recording with an FM modulation signal of sub-information having a lower frequency than the main information in the radial direction of the disk.

When the recording trace formed on the optical disk is a pit, the recording trace interval detecting means detects the interval between the recording traces by performing signal level discrimination using the RF reproduction signal level. When the optical disk is a magneto-optical disk, the recording trace formation section detecting means detects the section where the recording trace is formed by performing signal level discrimination using the magneto-optical reproduction signal level.

The sub-information signal reproducing means outputs the output from the inter-recording-trace-section detecting means or the recording-trace-forming-section detecting means on an optical disk on which the pits are formed or magneto-optical recording is performed. Is used as a sampling pulse to sample and hold the push-pull error signal to reproduce the sub information signal. The sub information signal is, for example, absolute time information that is address information to be written in advance.

[0017]

According to the present invention, there is provided an optical disk reproducing apparatus for reproducing an optical disk in which a main information signal is recorded as a recording trace along a guide groove including a sub information signal formed in a rotation direction of the optical disk. Then, a signal between the recording traces is detected by detecting a signal optically read from the data. The sub-information signal is reproduced according to the output signal from the optical signal detecting means in the detected section of the recording trace section. For example, the information in the section "1" where the amount of light reflected from the optical disk is large and which is larger than the threshold level is sampled, and is held below the threshold level to continuously reproduce desired absolute time information as a sub information signal. This optical disk reproducing apparatus can perform servo control by using one or both of a pit and a sub information signal which are main information signals.

Also, in an optical disk reproducing apparatus for reproducing an optical disk on which a recording trace of a main information signal is displaced in a radial direction of the disk by a sub information signal, the recording trace is read by a signal optically read from the optical disk. Is detected. The sub-information signal is reproduced according to the output signal from the optical signal detecting means in the section where the recording trace is made. Servo control can be performed using this sub information signal.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic hardware configuration of an optical disk reproducing apparatus according to the present invention.

The optical disk reproducing apparatus according to the first embodiment reproduces an optical disk on which a main information signal is recorded as a recording trace along a guide groove (groove) including a sub information signal formed in the rotation direction of the optical disk. The present invention relates to an optical disk reproducing device.

The optical disk reproducing apparatus includes a two-split push-pull optical detector 127 which is an optical signal detecting means for detecting a signal optically read from the optical disk.
An A / D conversion circuit 18 which is a section between recording traces for detecting a section between the recording traces of the output signal from the split-push-pull photodetector 127, and a section detected by the A / D conversion circuit 18 And a sampling and holding circuit 20 which is a sub-information signal reproducing means for reproducing the sub-information signal in accordance with the output signal from the two-split-pull-pull photodetector 127.

This optical disk reproducing apparatus is provided with a delay circuit 21 between the sample and hold circuit 20 for performing sample and hold based on the sampling pulse signal from the A / D converter 18. The operation of the delay circuit 21 will be described later with reference to FIG.

A read command signal (C
W) is supplied to the laser (LD) drive circuit 11. The laser (LD) drive circuit 11 supplies a drive signal to the optical head unit 12 so that an optimum light amount is obtained based on the read command signal.
The light is supplied to a laser diode 121 which is a light emitting element. The optimum light amount is specified in the so-called Orange Book.

The optical head unit 12 includes the laser diode 121, the collimating lens 122, the beam splitter 123, the objective lens 124, and the objective lens driving coil 1.
25, a converging lens 126 and a two-part push-pull photodetector 127.

The laser light emitted from the laser diode 121 is converted into a parallel light beam through a collimator lens 122, passes through a beam splitter 123, and passes through the objective lens 12.
4 The objective lens 124 is servo-controlled through an objective lens drive coil 125 by a drive signal supplied from a lens drive circuit 16 described later.
The laser beam is irradiated through the objective lens 124 onto the optical disc 13 on which so-called pits, which are recording traces, are formed. The return light reflected on the optical disc 13 according to the presence or absence of the pits is reflected by the beam splitter 123 through the objective lens 124 at right angles to the emission direction of the laser light. The reflected return light forms a beam image on the two-split push-pull light detector 127 via the converging lens 126.

The two-part push-pull photodetector 127
The supplied beam is received by a photodetector (for example, a photodiode) which is divided into two, and is converted into an electric signal. At this time, the two-split push-pull photodetector 127
Outputs the difference between the received electrical signals. When the difference between the electric signals is on the track, the difference is theoretically canceled to zero as described above. However, the output of the difference varies due to the influence of the first-order diffracted light from the surroundings and especially the pit component.

The two-part push-pull photodetector 127
This output signal is supplied to the amplifier 14, the matrix amplifier 17 and the amplifier 19, respectively. The signal via the amplifier 14 is supplied to the phase compensation circuit 15 as a servo error signal. The servo error signal phase-compensated by the phase compensation circuit 15 is supplied to a lens drive circuit 16. The lens drive circuit 16 supplies a drive control signal for controlling the position and the like of the objective lens 124 to an objective lens drive coil 125 in the biaxial actuator to perform servo control.

The signal passed through the matrix amplifier 17 is R
The signal is supplied to the A / D conversion circuit 18 as an F signal. This RF
The signal is converted into digital data by the A / D conversion circuit 18 and supplied to the subsequent signal processing circuit. The A / D conversion circuit 18 supplies a sampling pulse signal for controlling the respective timings of sampling and holding of a sample and hold circuit 20 described later via a delay circuit 21.

The signal passed through the amplifier 19 is supplied to a sample and hold circuit 20 as a push-pull error signal. The sample hold circuit 20 samples and holds the push-pull error signal according to the sampling pulse signal supplied from the A / D conversion circuit 18. The sample-and-hold circuit 20 samples information of a necessary portion, and holds the sampled information as information of an unnecessary portion, so that the sample-and-hold circuit 20 extracts and outputs only the necessary portion. For example, the absolute time information ATIP pre-recorded before recording on the optical disc 13 as a necessary part is the same as the absolute time information ATIP having the same quality as before recording which is not affected by the pit component from the sample hold circuit 20. You will get.

The signals used in the optical disk reproducing apparatus include a tracking error signal and an RF signal in ascending order of frequency.
A signal, a main information signal (pit information signal), and these frequencies are used.

When the optical disk reproducing apparatus reproduces the optical disk having the pits, which are the main information signals, formed along the guide groove including the sub information signal, the push-pull error of a frequency lower than the frequency of the main information signal is obtained. It is possible to stably obtain absolute time information recorded between pits in which signals are controlled so that diffraction of the pits does not affect the pits.

Next, the operation of the schematic block diagram will be described with reference to the timing chart shown in FIG. FIG. 2A shows a pit row P of recording traces recorded on an optical disk. When this pit row is traced, the RF signal output from the two-split-pull-pull photodetector 127 via the matrix amplifier 17 shows the RF envelope shown in FIG. That is, the amount of reflected light from the pit row P in which the pits are formed is small, and the amount of reflected light from the portion B between the pits is large. The RF signal is supplied to an A / D conversion circuit 18 and converted into digital data.

An A / D conversion circuit 18 for this RF signal
Sets the threshold level shown in FIG. For example, the A / D conversion circuit 18 outputs “1” when an RF signal level higher than the threshold level is input, and outputs a signal by discriminating “0” at an RF signal level lower than the threshold level. The A / D conversion circuit 18 supplies the level-discriminated output signal as a sampling timing signal as a synchronization timing signal of the sample-and-hold circuit 20.

The output signal shown in FIG. 2C indicates a sampling pulse signal output from the A / D conversion circuit 18. In accordance with the sampling pulse signal, the sampling pulse circuit 20 holds during the period of the level "0" indicating the main information signal from the pit, and performs wobbling recording during the period of the level "1" indicating the section between the pits. The sub information signal is sampled. This sampling pulse signal is delayed by a delay amount D shown in FIG.
To supply.

The push-pull error signal supplied to the sample-and-hold circuit 20 is used to determine how the pits are formed on the optical disk and how the reflection from the pits is divided. Is a signal having a relatively low frequency. Until now, reading the absolute time information ATIP from the push-pull error signal, for example, has not been performed stably due to errors due to the extremely narrow allowable range and the influence of pit diffraction.

Therefore, the delay circuit 21 suppresses the influence of the diffracted light due to the rear end of the pit 40 shown in FIG. 4 at the start of the first reading between the pits so as not to include at least the diffraction error due to the pit shape. It is provided to eliminate it. However, it is difficult to remove the influence of the diffracted light due to the start portion of the next pit formation (that is, the end portion between the pits) because it is unknown when the start portion comes.

Actually, for example, a compact disk signal in a currently used write-once type compact disk CD-WO has 3T to 11
It is written with a length up to T. Here, between short pits, the absolute absolute time information ATIP cannot be obtained from the guide groove because it is close to the diffraction limit of the beam. For example, 3 between pits
If the signals obtained at T and 4T are masked, unreliable short-time guide grooves can be avoided, and multiple information from long and reliable guide grooves can be obtained.

In order to remove the above uncertain part,
By setting the threshold level shown in FIG.
A short-time change portion E in the F signal can be easily masked. By using the sampling signal from the A / D conversion circuit 18 shown in FIG. 2F, a highly stable push-pull signal can be obtained.

As described above, the information between the pits affected by the diffraction of the pits can be detected and demodulated by delaying the start of the reading to detect the absolute time information not including the above error.

Another embodiment according to the optical disk reproducing apparatus will be described. This optical disk device relates to an optical disk reproducing device for reproducing an optical disk on which a recording trace of a main information signal is displaced in a radial direction of the disk by a sub-information signal and which is recorded and formed. In such an optical disc, for example, there is no guide groove, and a row of pits that are recording traces wobble in the radial direction.

Since the circuit configuration of this optical disk reproducing apparatus is the same as the circuit configuration shown in FIG. 1, it is an optical signal detecting means for detecting a signal optically read from the optical disk, given the same reference numeral. A two-split push-pull photodetector 127 and an A / D conversion circuit 18 which is a recording trace forming section detecting means for detecting the recording trace forming section.
And a sample-and-hold circuit 20 serving as a sub-information signal reproducing means for reproducing the sub-information signal in accordance with the output signal from the 2-split-pull-pull photodetector 127 in the section detected by the A / D conversion circuit 18. It consists of.

In the reproduction of an optical disk in which the pit train is modulated in the radial direction, in this case, by sampling the wobbled pit train, a frequency lower than the frequency of the main information signal is used to perform the FM modulation signal. The written sub-information is sampled and reproduced. That is, the region of level "0" shown in FIG. 2C is sampled, and R is held so that the region of level "1" is held.
It is clear that by discriminating the level of the F signal level, the sub information signal can be stably reproduced from the information of only the pit train. A recording medium without such a guide groove, which is found in the standards of a magneto-optical disk (MO) and a write-once disk, is important for improving the recording density.

By sampling necessary information in accordance with the sampling pulse signal from the A / D conversion circuit, address information can be read at the time of reproduction with the same quality as before recording. Servo control can also be performed using one or both of the main information signal and the sub information, which are recording traces.

[0045]

According to the optical disk recording apparatus of the present invention, an optical disk reproduction for reproducing an optical disk on which a main information signal is recorded as a recording trace along a guide groove including a sub information signal formed in a rotation direction of the optical disk. In the device,
Optical signal detecting means for detecting a signal optically read from the optical disc; and detecting a section between the recording traces of the output signal from the optical signal detecting means to output a sampling signal and detecting the detected signal. The sub-information signal is reproduced by sampling the output signal from the optical signal detecting means using the sampling signal, and a recording mark interval detecting means for masking the output of the sampling signal based on the length of the section. With such a sub information signal reproducing means, it is possible to stably obtain the absolute time information which is the sub information signal written in the section between the recording traces. Specifically, when the section between the recording traces (pits) is short such that it is close to the diffraction limit of the light beam, considering that an accurate sub information signal cannot be obtained from the guide groove,
By masking the output of the sampling signal, it is possible to avoid the guide groove in the indeterminate short section between the recording traces and obtain long and reliable sub-information from the guide groove. Further, the optical disk reproducing apparatus can perform servo control of the optical head using either the main information signal from the pit written on the optical disk or the absolute time information as the sub information signal.

Also, the optical disk apparatus according to the present invention is an optical disk reproducing apparatus for reproducing an optical disk formed by recording traces of a main information signal being displaced in the radial direction of the disk by a sub information signal. Optical signal detecting means for detecting a signal read at a time, a recording trace forming section detecting means for detecting a recording trace forming section, and the optical signal detecting means for a section detected by the recording trace forming section detecting means And a sub-information signal reproducing means for reproducing the sub-information signal corresponding to the displacement of the recording trace in the radial direction of the disk in accordance with the output signal from the optical disk. The apparatus performs wobbling recording of pits in a recording trace formation section in the radial direction by FM modulation at a lower frequency than the main information signal. Signal can be reproduced stably, the head light using the sub information signal may be servo-controlled.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a first embodiment of an optical disk reproducing apparatus according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the optical disc reproducing apparatus of the embodiment.

FIG. 3 is a schematic diagram illustrating an example of a light receiving image of a two-split push-pull photodetector.

FIG. 4 is a schematic diagram illustrating an example of a light receiving image of a two-split push-pull photodetector.

[Explanation of symbols]

 10 Input terminal 11 Laser drive circuit 12 Optical head unit 13 Optical disk 14 19 ·················································································· A / D conversion circuit Delay circuit 127... 2 split-push-pull photodetector

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 005-7/095 G11B 27/28

Claims (2)

(57) [Claims] 1. An optical disk reproducing apparatus for reproducing an optical disk on which a main information signal is recorded as a recording trace along a guide groove including a sub information signal formed in a rotation direction of the optical disk, wherein the optical information is optically read from the optical disk. Optical signal detecting means for detecting a signal; detecting a section between the recording traces of the output signal from the optical signal detecting means to output a sampling signal; and outputting a sampling signal based on the length of the detected section. a recording trace between section detecting means for masking the output of the sampling signal, the recording trace the output signal from the optical signal detecting means
An optical disc reproducing apparatus comprising: a sub-information signal reproducing unit that reproduces the sub-information signal by sampling with a sampling signal output from the inter-segment detecting unit . 2. An optical disk reproducing apparatus for reproducing an optical disk recorded and formed by displacing a pit string of a main information signal in a radial direction of the disk by a sub information signal, wherein the optical system detects a signal optically read from the optical disk. Signal detection means, recording trace formation section detection means for detecting a formation section of each pit in the pit row , and an output signal from the optical signal detection means for a section detected by the recording trace formation section detection means. the pitch in accordance with
An optical disc reproducing device comprising: a sub information signal reproducing means for reproducing the sub information signal corresponding to the displacement of the train in the radial direction of the disk.