JP2002203322A - Optical reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium, in which the structure of a groove resulted from wobbles arranged at both sides of the groove does not affect the polarization direction of laser beams emitted for reproducing a signal. SOLUTION: The light intensity detected in areas 113A, 113D and the light intensity detected in areas 113B, 113C are inputted to an adder 1151 in a wobble detecting circuit 115 through a reproduced signal amplifier circuit 114. The light intensity added by the adder 1151 is binarized in a comparator 1153 based on 0-level after the noise is removed by a band-pass filter 1152, then this binarized signal is transmitted to a PLL circuit 117. By the PLL circuit 117, synchronizing signals of twice per one period are produced on the basis of the rise timing 1 and fall timing of the transmitted signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical recording medium capable of recording or reproducing at high density and an optical reproducing apparatus therefor.

[0002]

2. Description of the Related Art Recently, a magneto-optical recording medium is known as a recording medium capable of recording and / or reproducing at high density. In this medium, a track is composed of a land and a groove. Recording or reproduction is possible for both. In order to increase the recording density, the address information is recorded not as a normal magneto-optical signal but as a wobble on the wall of the groove, and there is a data area behind the address information. A wobble different from the wobble on which information is recorded is formed on both or one of the grooves. And
The wobble formed in the data area is reproduced, and a synchronization signal for recording or reproducing a signal is generated from the reproduced wobble signal.

[0003]

However, when a clock is generated based on a wobble signal, it is desirable that the shorter the frequency or cycle of the wobble is, the higher the accuracy will be. However, as shown in FIG. As the length decreases, crosstalk improves. In addition, as shown in FIG. 21, the error rate increases as the crosstalk increases.

In the structure of a conventional magneto-optical recording medium,
Since the wobbles 151 provided on both sides of the groove have the same phase, when the laser beam 152 irradiates the groove G, the reflected light is not a polarized wave based on the magnetization of the original signal, but the light of the groove G. It has a polarized wave component in the same direction as the arrow 153 indicating the direction of the groove determined by the wobbles 151 provided on both sides. Further, when the laser beam 154 is irradiated, it has a polarized wave component in the same direction as the arrow 155 indicating the direction of the groove G at that position. Therefore, the conventional land / groove structure has a problem that the originally recorded signal cannot be accurately detected.

Therefore, the present invention solves such a problem,
Provided is an optical recording medium capable of generating a synchronization signal for reproducing a recording signal from a wobble signal provided in a data area and reproducing the recording signal based on the generated synchronization signal, and an optical reproducing apparatus for the same. Things.

[0006]

According to the present invention, there is provided a wobble which comprises a land and a groove, and has a groove on a wall on both sides of the groove in a signal recording area, the width of the groove changing at a predetermined period in the traveling direction of the laser beam. An optical reproducing apparatus for reproducing an optical recording medium provided with: a synchronizing signal generating circuit for generating a synchronizing signal from a wobble reproduction signal; and a signal in a signal recording area based on the synchronizing signal generated by the synchronizing signal generating circuit. And an optical means for reproducing.

The present invention comprises a land and a groove, and the groove in the signal recording area is provided on both sides of the groove so that the width of the groove changes at a predetermined cycle in the traveling direction of the laser beam. The groove in the address area includes wobbles, and the groove in the address area is an optical reproducing apparatus that reproduces an optical recording medium that includes wobbles having the same phase on both sides of the wall. It is characterized by including a synchronization signal generation circuit for generating a synchronization signal, and optical means for reproducing a signal in a signal recording area based on the synchronization signal generated by the synchronization signal generation circuit.

The present invention comprises a land and a groove, and the groove in the signal recording area is provided on both side walls so that the width of the groove changes at a predetermined cycle in the traveling direction of the laser beam. An optical reproducing apparatus for reproducing an optical recording medium including a wobble and another wobble having a predetermined period on at least one wall thereof, wherein the wobble provided on a groove wall of the signal recording area A synchronizing signal generation circuit that generates a synchronizing signal from the reproduction signal, and an optical unit that reproduces a signal in a signal recording area based on the synchronizing signal generated by the synchronizing signal generation circuit;
It is characterized by including.

Further, the present invention is characterized in that the optical reproducing apparatus further includes an address detection circuit for detecting address information from a wobble reproduction signal provided in the address area.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described with reference to the drawings. In the following description, portions denoted by the same reference numerals indicate the same or corresponding portions. FIG. 1 is a perspective view of an optical recording medium according to the present invention. The optical recording medium 10 has a structure in which a magnetic film 2 is formed on a translucent substrate 1 made of polycarbonate, glass, or the like. The magnetic film 2 includes a reproducing layer made of GdFeCo or the like and a recording layer made of TbFeCo or the like. The optical recording medium 10 has a planar structure including the groove 3 and the land 4.
The wobbles 5 and 5 in which the phase of the wobble provided on one wall is different from the phase of the wobble provided on the other by 180 degrees are provided. That is, the wobbles 5 and 5 are provided such that the width of the groove 3 or the land 4 changes at a predetermined cycle in the traveling direction of the laser beam.

Referring to FIG. 2, the planar structure of the optical recording medium 10 will be described in more detail. The optical recording medium 10 includes an address area A and a data area D, and the wobbles 5 are formed on both sides of the groove 3 of the address area A and the data area D. The wavelength and amplitude of the wobble 5 will be described with reference to FIG. Wobble 5 wavelength W
Is in the range of 0.8 to 20 μm, preferably 1.2.
５5 μm. The amplitude h of the wobble 5 is
The range is ± 10 to ± 200 nm, preferably ± 2.
The range is 0 to ± 60 nm. In the present invention, as described later, a synchronization signal used for reproducing a recording signal is generated from a reproduction signal of the wobble 5 in the data area D.

In the optical recording medium 10 shown in FIG. 2, address information is also recorded by the wobble 5. The address information is recorded, for example, by bi-phase modulation. With reference to FIG. 4, recording by the biphase modulation method will be described. Of the binary address information, “0” is represented by a waveform 41 and “1”
Is represented by a waveform 42, the address information (1
The waveform when recording “0110) by biphase modulation is a waveform 43. Therefore, the wobble waveform provided on one wall of the groove 3 of the address area A becomes a waveform 44, and the wobble waveform provided on the other wall becomes a waveform 45. The waveform 44 and the waveform 45 have a relationship equivalent to that obtained by symmetrically moving the waveform 44 in the tracking direction about the center of the groove 3 as an axis. Referring to FIG.
A method of recording an address in the address area A will be described. A wobble 51 and a wobble 52 are formed on one wall of the groove 31 of the address area A, and a wobble 53 and a wobble 54 are formed on the other wall. And wobbles 53 and 54 are wobbles 51 and 5
2 corresponds to a symmetrical movement in the tracking direction about the center of the groove 31 as an axis. A wobble 51 and a wobble 55 are formed on one wall of the next groove 32, and a wobble 53 and a wobble 56 are formed on the other wall. Also in this case, wobbles 53 and 56
Correspond to wobbles 51 and 55 symmetrically moved in the tracking direction about the center of groove 32 as an axis. Further, a wobble composed of a wobble 57 and a wobble 55 is formed on one wall of the next groove 33, and on the other wall,
A wobble composed of the wobble 58 and the wobble 56 is formed. Also in this case, wobbles 58 and 56 are wobbles 5
7 and 55 correspond to those obtained by symmetrically moving in the tracking direction about the center of the groove 33 as an axis. When wobbles are formed on both sides of the groove, addresses G1 and G0 are stored in the address area of the groove 31.
Are recorded with addresses G1 and G2, the grooves 33 are recorded with addresses G3 and G2, the land 41 is recorded with the address L1, and the land 42 is recorded with the address L2. Here, the address G1 and the address L1, and the address G2 and the address L2 are the same information. This is because the wobbles 51 and 53 on both sides indicating the address information G1 are the same as the wobbles 53 and 51 on both sides indicating the address L1. Therefore, in the groove 31, the address G1 is
Address L1 and groove 32 address G2.
, The address L2 in the land 42, and the groove 3
3, the address G3 is detected. Such a method of recording address information is hereinafter referred to as a staggered method.

Referring to FIG. 6, the format of an address recorded in the address area A will be described. The address area A has an area having a length of 96 data bytes, and the data amount of the address part is 96 bits. That is, the length of one bit of the address part is eight times the recording bit.
When the bit length of the recording bit is 0.22 μm, the length of the data bit of the address part is 1.76 μm. The configuration of the address area A is the same as that of the preamble (P
A) 6 data bytes as 91, address 1 (Add
res1), 42 data bytes long, Reserve
ed96 is 2 data bytes long, address 2 (Add
less2) 42 data bytes length, A pattern 1
01 for 2 data bytes, address mark (AM)
102 is two data bytes long. Address 1 (Address 1) is a first synchronization signal (SYNC).
1) 4 bits as 92, frame address (Fram
The address 93 includes 8 bits, the track address 94 includes 16 bits, and the CRC 95 includes 14 bits. Address 2 (Address2) is a second synchronization signal (SYNC).
2) 4 bits as 97, frame address (Fram
The address 98 consists of bits, the track address 99 consists of 16 bits, and the CRC 100 consists of 14 bits. Furthermore,
The preamble 91 contains (1010110101010)
The first synchronization signal 92 includes (1110001)
The signal of (0) is provided to Reserved 96 (101).
0) is included in the second synchronization signal 97 (10001).
The signal of (110) is represented by the A pattern 101, the signal of (10) is represented by the AM pattern 102, and the signal of (1100) is represented by “0” in the waveform 41 and “1” in the waveform. , Respectively, are recorded.

Referring to FIG. 7, another embodiment of the optical recording medium according to the present invention will be described. The planar structure of the optical recording medium shown in FIG. 7 is different from that shown in FIG. 2 only in the waveforms of wobbles provided on both sides of the groove 3 in the address area A. In the example shown in FIG. 7, the phases of the wobbles 6 provided on both sides of the groove 3 are the same.
In the address area A, an address is recorded by a staggered method using a wobble 6 by a biphase modulation method.
The other description is the same as the description of FIGS.

Further, the planar structure of the optical recording medium according to the present invention may be as shown in FIG. The optical recording medium shown in FIG. 8 differs from that shown in FIG. 2 only in that the groove in the address area A has a wobble 6 on one wall and a straight line 7 on the other wall. The other description is the same as in FIGS. In the optical recording medium having the structure shown in FIG. 8, one of the optical recording media serves both the address of the land and the groove, so that the recording density can be improved accordingly.

Further, the planar structure of the optical recording medium according to the present invention may be as shown in FIG. The optical recording medium shown in FIG. 9 is different from that shown in FIG. 2 in that the grooves in the address area A have wobbles formed on both side walls, and the wobbles are formed by FM-modulated wobbles 8. It is just a point. For other explanations, see FIG.
The description is omitted because it is the same as 3, 4, 5, and 6.

Further, the planar structure of the optical recording medium according to the present invention may be as shown in FIG. The optical recording medium shown in FIG. 10 differs from that shown in FIG. 2 in that grooves in the address area A and the data area D have wobbles formed on both side walls, and the wobbles are FM-modulated wobbles. 9 is only formed. The other description is the same as in FIGS. Therefore, in the optical recording medium shown in FIG. 10, the address of the data area is recorded on the groove wall of the data area by the wobble 9 in which the FM modulation is performed.

Next, an optical reproducing apparatus for the above-described magneto-optical recording medium 10 will be described. Referring to FIG. 11, an optical reproducing apparatus includes an optical head 112, a reproduced signal amplifying circuit 11
4. Signal demodulation circuit 118, wobble detection circuit 115, address detection circuit 116, PLL circuit 117, laser drive circuit 119, servo circuit 111, spindle motor 11
Consists of zero. The optical head 112 focuses and irradiates the laser beam on the magneto-optical recording medium 10 and
The reflected light from the optical recording medium 10 is detected by a photodetector 113 disposed in the optical recording medium 12. Also, the reproduction signal amplifying circuit 114
Amplifies the reproduction signal from the photodetector 113 in the optical head 112, focus error signal, tracking error signal, etc. to the servo circuit 111, reproduction signal to the signal demodulation circuit 118, wobble signal in the data area D The wobble signal in the address area A is sent to the wobble detection circuit 115 and to the address detection circuit 116, respectively. The servo circuit 111 controls the optical head 112 based on the sent focus error signal, tracking error signal, and the like.
And the spindle motor 110 is controlled. The signal demodulation circuit 118 converts the reproduced signal modulated by a predetermined modulation method into P
The signal is demodulated based on the synchronization signal sent from the LL circuit 117 and is sent as reproduced data to an output device (not shown). The wobble detection circuit 115 binarizes the sent wobble signal with a comparator, and converts the binarized signal into a PL signal.
Send to L circuit 117. The address detection circuit 116 binarizes the received wobble signal by a comparator, demodulates the binarized signal, detects address information, sends it to a microcomputer (not shown), and uses it for system control. The PLL circuit 117 generates a synchronization signal based on the received binary signal, and sends the signal to the signal demodulation circuit 118 and the laser drive circuit 119.
The laser drive circuit 119 drives a semiconductor laser (not shown) in the optical head 112 based on the transmitted synchronization signal, and reproduces a recording signal based on the synchronization signal.

The detection of the wobble 5 formed in the data area D will be described with reference to FIGS. The detection unit of the photodetector 113 has four regions 113A and 11A.
3B, 113C, and 113D.
3A and 113D and the regions 113B and 113C are arranged so as to be in the direction of the arrow 120 indicating the traveling direction of the laser beam. In this case, the light intensity detected in the regions 113A and 113D and the light intensity detected in the regions 113B and 113C are input to the adder 1151 in the wobble detection circuit 115 via the reproduction signal amplifier circuit 114.
The light intensity added by the adder 1151 is subjected to noise removal by a bandpass filter 1152,
At 53, the signal is binarized based on the 0 level, and the binarized signal is sent to the PLL circuit 117. Comparator 1
The signal sent to 153 is signal (a) as shown in FIG. Therefore, a signal obtained by binarizing this is (b)
A signal as shown in FIG. The PLL circuit 117 generates a synchronization signal twice in one cycle based on the rising timing 130 and the falling timing 131 of the transmitted signal (b). Further, since the wavelength W of the wobble 5 provided in the data area D is constant and the wavelength W is in the range of 0.8 to 20 μm, it is possible to generate a synchronization signal at a relatively short interval, and Can be reproduced accurately.

FIG. 14 is a diagram for explaining the detection of the wobble 5 in the data area D. The difference from FIG. 12 is that the light intensity from the wobble 5 is changed in the direction perpendicular to the arrow 120 which is the signal direction of the laser beam. The only difference is that the light intensity added in the direction of arrow 121 is input to the adder 1151. The other description is the same as that of FIG.

The address information recorded in the address area A can be detected with the same circuit configuration as that shown in FIGS. FIG. 19 shows the relationship between the wobble length and the crosstalk of the optical recording medium described above.
The width of the groove is 0.6 μm and the amplitude is ± 60 nm. In this case, even if the wobble length is reduced, the crosstalk does not increase. At present, it has been confirmed that crosstalk does not increase up to a wobble length of 0.8 μm. Accordingly, by shortening the wobble length and generating a synchronizing signal from the shortened wobble, it is possible to reproduce with good characteristics.

Referring to FIG. 16, cutting of an optical recording medium having the above-described wobble 5 in the data area D will be described. The cutting device shown in FIG. 16 includes an Ar laser 160 that generates a laser beam of a predetermined wavelength, for example, 458 nm, and a laser noise reduction circuit 161 that removes noise of the laser beam from the Ar laser 160.
An EO modulator 162 that changes the power of the laser beam based on a predetermined control signal 163; a reflection mirror 164 that reflects the 458 nm laser beam and transmits the laser beam from the HeNe laser 166; An objective lens 165 for focusing on the master 168, and a HeNe laser 1 with a wavelength of 633 nm for focus servo
66 and a reflection mirror 167 that reflects the laser beam from the HeNe laser 166. Since the predetermined control signal 163 indicates the intensity of the power of the laser beam, the cutting device shown in FIG.
A wobble 5 having a simplified structure is formed on both sides of the groove. Therefore, the laser beam exiting the EO modulator 162 is a laser beam whose power changes at a predetermined cycle, is reflected by the reflection mirror 164, and is reflected by the objective lens 165.
And is irradiated onto the glass master 168. As a result, the wobble 5 shown in FIG. 2 is formed on both side walls of the groove.

The apparatus for cutting the optical recording medium 10 according to the present invention may be the apparatus shown in FIG. In the device shown in FIG. 17, an EO deflector 170 is inserted next to the laser noise reduction circuit 161 in FIG. 16, and a control signal 172 output from the amplitude modulator 171 is provided.
The EO deflector 170 is controlled by the. The other description is the same as that of FIG. In the device shown in FIG. 17, the envelope of the control signal 172 is the same as that shown in FIG.
Control signal 172 so as to correspond to the waveform of wobble 5
Is produced. Therefore, on the glass master 168, the laser beam repeats a reciprocating motion at a high frequency in the tracking direction, and forms the wobble 5 on both side walls of the groove.

Further, the optical recording medium 10 according to the present invention
May be the device shown in FIG. In the device shown in FIG.
The laser beam generated from zero is split into two, and one is used for a wobble formed on one wall of the groove, and the other is used for a wobble formed on the other wall of the groove. Therefore, the laser noise reduction circuit comprises the laser noise reduction circuit 161A and the laser noise reduction circuit 1
There are two EO deflectors 61B and EO deflectors 170A and 170B. A signal 180 for controlling the movement of the laser beam in the tracking direction is input to one EO deflector 170B, and a control signal 181 obtained by inverting the control signal 180 by an inverter 182 is input to the other EO deflector 170A. . Therefore, EO
The laser beam emitted from the deflector 170A and the laser beam emitted from the EO deflector 170B move symmetrically about the center of the groove as an axis to form the wobble 5 shown in FIG. Second Embodiment Another planar structure of the optical recording medium according to the present invention will be described with reference to FIG. The cross-sectional structure, the magnetic film to be used, and the like are the same as those described in the first embodiment, and a description thereof will not be repeated. In the optical recording medium shown in FIG. 22, wobbles 220 are formed on the opposite side walls of the groove 3 of the address portion A, in which wobbles having the same phase are superimposed with wobbles having opposite phases. Addresses for the groove 3 and the land 4 are recorded in wobbles 220 provided on both sides of the groove. The data portion D is provided with wobbles having phases opposite to each other. The wobble 2 is added to the address portion A.
The same effect as that of the first embodiment can be obtained by providing 20. Third Embodiment By providing wobbles 5 having phases opposite to each other on both sides of a groove in a data portion, the amount of leakage of a recorded magneto-optical signal into the reproduction characteristics can be reduced. If they are at the center of
When tracking deviates from the center of the groove 3 due to the tilt of the substrate or the like and approaches the wobble 5 provided on the wall of the groove 3, leakage occurs in the reproduction characteristics due to the effect of the wobble 5.

Therefore, in the third embodiment,
An object of the present invention is to provide an optical reproducing apparatus for eliminating an amount of leakage into the reproduction characteristics of an optical recording medium having wobbles 5 having phases opposite to each other in a data section. With reference to FIG. 23, the relationship between the position of the laser beam applied to the groove 3 and the obtained reproduction signal will be described. The laser beam is at the center of the groove 3, that is,
When the light is irradiated to the position indicated by the spot 230, the waveform of the reproduced signal is as shown in FIG. on the other hand,
When the position of the irradiated laser light is shifted upward on the paper as shown by the spot 231, the waveform of the reproduced signal becomes a waveform having an envelope periodically as shown in FIG. In addition, the irradiated laser light is spot 232.
23, when the waveform is shifted downward on the paper, the waveform of the reproduced signal has an envelope as shown in FIG. 23C, but has a waveform that is shifted by a half cycle from the waveform of FIG. (A),
When a reproduced signal having a waveform as shown in (c) is obtained, the amount of leakage into the reproduction characteristics is detected as (h / 2) / H.
Therefore, in order to remove the leakage amount, tracking should be performed at the center of the groove 3. Embodiment 1 Referring to FIGS. 24 and 25, 1 for removing the leakage amount
One embodiment will be described. When the position indicated by the spot 240 is irradiated with the laser light, a reproduced signal having a waveform shown in FIG. 24C is obtained. The reproduced waveform of the wobble 5 provided on the walls on both sides of the groove 3 is a waveform shown in FIG. When the wobble waveform shown in (a) is binarized by a comparator, the signal in (b) is obtained. The first amplitude, which is the amplitude of the reproduced signal at the first timing 241 which is the rising timing of the signal in FIG. 2B, and the reproduction signal at the second timing 242, which is the falling timing of the signal shown in FIG. And a second amplitude which is an amplitude. [1st amplitude−second amplitude] is calculated from the detected first and second amplitudes, and [1st amplitude] is calculated from the tracking signal used for tracking to the position indicated by the spot 240. [2nd amplitude] can be used as a new tracking signal, so that the laser beam can be tracked to the center of the groove 3, and as a result, leakage of the magneto-optical signal into the reproduction characteristics can be eliminated. Becomes possible. [First
Is larger in proportion to the amount of deviation from the center of the position of the laser light applied to the groove 3, and if the tracking signal is corrected with the amount of deviation, the value of the groove 3 becomes larger. Will be able to track to the center.

Referring to FIG. 25, a description will be given of an optical reproducing apparatus for removing the leakage amount according to the first embodiment. FIG.
The optical reproducing apparatus shown in FIG. 11 is obtained by adding a tracking correction circuit to the optical reproducing apparatus shown in FIG. 11 in the first embodiment, and the operation other than the operation for removing the leakage amount is the same as that shown in FIG. The description is omitted because it is the same as 11. The reproduction signal detected by the photodetector 113 in the optical head 112 is sent to a reproduction signal amplifier circuit 114. Among the reproduction signals, the reproduction signal of the magneto-optical signal is sent to the signal demodulation circuit 118 and the tracking correction circuit 250, and the tracking error signal is sent to the tracking correction circuit. The processing of the reproduction signal of the magneto-optical signal sent to the signal demodulation circuit 118 is the same as described above. A focus error signal of the reproduction signal is sent to the servo circuit 111, and is used for focusing on an objective lens in an optical head (not shown). Further, of the reproduced signals, the reproduced signal of the wobble 5 provided on the walls on both sides of the groove 3 is sent to the wobble detection circuit 115, and the wobble detection circuit 1
At 15, the wobble signal shown in FIG.
The wobble signal is sent to the tracking correction circuit 250. The tracking correction circuit 250 detects a tracking shift amount based on the transmitted reproduction signal of the magneto-optical signal and the wobble signal, and corrects the tracking error signal based on the detected shift amount. The corrected tracking error signal is sent to the servo circuit 111 and used for tracking the objective lens in the optical head 112.

Referring to FIG. 26, the operation of tracking correction circuit 250 will be described in detail. The reproduction signal of the magneto-optical signal shown in (c) of FIG.
The wobble signal shown in FIG. 24A is input to the wobble synchronization signal generation circuit 263. The wobble synchronization signal generation circuit 263 compares the input wobble signal (a) and generates a binarized signal shown in FIG. Thereafter, a first timing signal (d) synchronized with the rising timing of the binarized signal (b)
(Shown in FIG. 24) and a second timing signal (e) synchronized with the falling timing of the binarized signal (b)
(Shown in FIG. 24), the first timing signal (d) is sent to the sample and hold circuit 262, and the second timing signal is sent to the sample and hold circuit 261.
send. The sample hold circuit 261 changes the amplitude of the reproduction signal (c) of the magneto-optical signal input from the reproduction signal amplification circuit 114 in synchronization with the second timing signal (e) sent from the wobble synchronization signal generation circuit 263. Detect
After holding the value as the second amplitude, the integration circuit 2
Send to 64. Further, the sample-and-hold circuit 262 synchronizes with the first timing signal (d) sent from the wobble synchronization signal generation circuit 263, and
After detecting the amplitude of the reproduced signal (c) of the magneto-optical signal inputted from the input terminal 14 and holding the value as the first amplitude,
It is sent to the integration circuit 265. The integrating circuits 264 and 265 integrate the transmitted signal and subtract the integrated signal into a subtractor 266.
Send to The subtractor 266 calculates the second value from the integrated value of the first amplitude.
Is subtracted from the integrated value of the amplitude of
Input to the terminal. On the other hand, a tracking signal used for tracking is input to the + terminal of the subtractor 267, and the subtractor 267 converts the tracking signal into the first signal.
Difference between the amplitude of the reproduction signal of the magneto-optical signal detected in synchronization with the timing signal and the amplitude of the reproduction signal of the magneto-optical signal detected in synchronization with the second timing signal, that is, the reproduction signal of the magneto-optical signal Is subtracted, and the result is output to the servo circuit 111 as a new tracking signal. Therefore, tracking deviation can be corrected by the tracking correction circuit 250 shown in FIG. 26, and as a result, leakage of the magneto-optical signal into the reproduced signal can be removed.

The tracking correction circuit is not limited to the one shown in FIG. 26 but may be one shown in FIG. The wobble signal (a) and the reproduced signal (c) of the magneto-optical signal are input to the multiplier 280, these signals are multiplied, and the result is sent to the minus terminal of the subtractor 267. The subtractor 267 is
From the tracking signal input to the + terminal, the multiplier 28
An operation of subtracting the signal sent from 0 is performed, and the result is output to the servo circuit 111 as a new tracking signal.

As described above, the tracking correction circuit shown in FIGS. 26 and 27 detects the reproduction signal of the magneto-optical signal, corrects the tracking signal at all times, and performs tracking based on the result. No leakage occurs in the detected reproduction signal of the magneto-optical signal. Second Embodiment With reference to FIGS. 28, 29, and 30, a description will be given of a second embodiment in which leakage of the magneto-optical signal into the reproduction characteristics is removed. In the magneto-optical recording medium 39 according to the present invention, the TOC area is provided on the inner peripheral portion 392 and the outer peripheral portion 391. In the second embodiment, the TOs provided on the inner peripheral portion 392 and the outer peripheral portion 391 are provided.
Information about the leakage amount is recorded in both or one of the areas C, and the leakage is removed from the reproduction signal by detecting this information at the time of reproduction. FIG. 29 shows a circuit configuration for removing leakage. After a reproduction signal is input to a terminal 40 and noise is removed by a band-pass filter (BPF) 41,
The signal is sent to the PLL circuit 42 and the correction signal generation circuit 44. P
A signal having a wobble waveform provided on both sides of the groove shown in FIG. 41A is sent to the LL circuit 42. The PLL circuit 42 detects a synchronization signal from the wobble waveform shown in FIG. The signal is sent to the laser drive circuit 119 and the signal demodulation circuit 118 through the signal, and the signal is reproduced in synchronization with the synchronization signal. The correction signal generation circuit 44 includes a terminal 45
The phase and amplitude of the signal (a) are made equal to the phase and amplitude of the wobble waveform of the signal (b) on the basis of the information on the leakage amount recorded in the TOC area of the magneto-optical recording medium 39 input from the MPU. And sends it to the subtractor 47.
Further, a magneto-optical reproduction signal on which the wobble waveform shown in (b) is superimposed is input from a terminal 46 to a subtractor 47. The subtracter 47 performs an operation of subtracting the corrected waveform of the signal (a) from the waveform of the signal (b) to generate a signal (c). The generated signal (c) is sent to a decoder (not shown), and after a predetermined demodulation, is extracted as a reproduced signal. As a result, leakage into the reproduced signal due to the wobble is removed. Third Embodiment With reference to FIGS. 31 and 32, a description will be given of a third embodiment in which leakage of the magneto-optical signal into the reproduction characteristics is removed. Example 3
In, the correction amount to be changed is determined based on the correction amount recorded in the TOC area of the magneto-optical recording medium 39 shown in FIG. 28, and the error rate of the reproduced signal for each changed correction amount is detected. Thereafter, a correction amount at which the error rate is minimized is determined, and a signal corresponding to the determined correction amount is detected as a reproduction signal. FIG. 31 shows a circuit used in the third embodiment. The correction amount generation circuit 420 includes the TOC
The correction amount detected from the region is input, and the correction amount generation circuit 420 determines the range of the correction amount to be changed based on the input correction amount, and sends the range to the subtracter 422. On the other hand, terminal 4
21 to the subtractor 422, the reproduced signal is input to the subtractor 4.
22 performs an operation of subtracting each correction amount determined from the reproduction signal, and sends the result to the error rate detection circuit 423. The error rate detection circuit 423 detects an error rate for each correction amount. Since the error rate for each correction amount has the relationship shown in FIG. 32, the error rate detection circuit 423 determines the correction amount that minimizes the error rate,
A reproduction signal corresponding to the determined correction amount is output from a terminal 424. In this case, the range of the correction amount to be changed is 0.3 to 3 times the correction amount. Fourth Embodiment With reference to FIGS. 33, 34, and 35, a description will be given of a fourth embodiment in which the leakage of the magneto-optical signal into the reproduction characteristics is removed. The magneto-optical recording medium 440 has a TOC area on an inner peripheral portion 392 and an outer peripheral portion 391, and an area for recording information related to a reproduction signal (hereinafter, referred to as a specific area) in a signal recording area 445.
441 and 443 and signal regions 442 and 444 are formed as a set. In the specific areas 441 and 443,
[11111 ...], [00000 ...], [10
10101...] Are reproduced, and these signals are reproduced before reproducing the signals.
These signals are equivalent to a reproduced signal in which no magneto-optical signal is recorded. That is, only the signal based on the wobble waveform is obtained. Therefore, by subtracting this signal from the reproduced signal, the amount of leakage can be eliminated. [11111 ...] and [00000 ·
..] And [1010101...] Are input, and the reproduced signal shown in FIG. On the other hand, terminal 45
45, the reproduced signal shown in (e) of FIG.
Of the subtractor 453 in synchronization with this.
The signal (d) is input from the waveform memory 451 to the terminal. The subtractor 453 subtracts the input signals (d) and (e) to obtain a signal (f) without leakage,
Output from terminal 454. Then, the signal demodulation circuit 1
18 and is extracted as a reproduced signal. In this case, [11111 ...], [00000 ...],
The leakage amount was detected from the signal [1010101...], But the leakage amount was similarly detected even when the magnetization of the reproducing layer of the magneto-optical recording medium was aligned in one direction by an external magnetic field applying means such as a magnetic head. it can. Fifth Embodiment With reference to FIGS. 36 and 37, a fifth embodiment for eliminating leakage of the magneto-optical signal into the reproduction characteristics will be described. Terminal 47
0 is input to the A / D converter 471 for A / D conversion.
After the conversion, it is sent to the subtractor 475 and the synchronous detection circuit. The synchronous detection circuit 472 detects a reproduced signal corresponding to one wavelength of the wobble waveform shown in FIG. 37 from the transmitted reproduced signal, and sends it to the adder 473. The adder 473 is 1
The reproduction signals for the wavelengths are added in a range of 100 to 10000 times and averaged. The result is sent to the waveform memory 474. The reproduced signal after the A / D conversion is input to the + terminal of the subtractor 475, and in synchronism therewith, an averaged signal is input from the waveform memory to the-terminal. The subtracter 475 can eliminate leakage by performing an operation of subtracting the averaged signal from the input reproduced signal. Sixth Embodiment With reference to FIG. 38, a description will be given of a sixth embodiment in which leakage of the magneto-optical signal into the reproduction characteristics is removed. The waveform B of the signal (g) represents a signal of 4 bytes, and the waveform C of the signal (h) represents a signal of the next 4 bytes. Waveform A
Represents a wobble waveform of the same phase formed on both sides of the groove. In the sixth embodiment, the waveform B of the signal (g)
Is subtracted from the waveform A to obtain a signal (i). Further, the signal (j) is obtained by adding the waveform A to the waveform C of the signal (h).
When the amplitude of the waveform A is A1, the amplitude of the waveform B is B1, the amplitude of the waveform C is C1, the amplitude of the signal (i) is Bh, and the amplitude of the signal (j) is Ch, (Ch−Bh) / 2 = [(C1 + A
1)-(B1-A1)] / 2 = A1, so that a reproduced signal from which the leakage amount has been eliminated can be obtained.

In the second to sixth embodiments, the description has been given of the case where the reproduction signal is directly corrected to eliminate the leakage into the reproduction signal. However, the tracking error signal is corrected to irradiate the magneto-optical recording medium. By controlling the position of the laser beam to be applied, it is possible to eliminate leakage into the reproduced signal.

[0031]

According to the present invention, since the polarization direction of the laser beam applied to the optical recording medium is not affected by the shape of the groove, the recorded signal can be reproduced accurately. Further, according to the present invention, since the wavelength of the wobble formed in the data area is as short as 20 μm or less, a high-frequency synchronization signal can be generated, and the recorded signal can be reliably reproduced.

Further, according to the present invention, wobbles in which the width of the groove changes at a predetermined period in the traveling direction of the laser beam can be easily formed on both sides of the groove. Further, according to the present invention, even if leakage occurs in the reproduction characteristic of the magneto-optical signal, the leakage can be easily removed.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical recording medium according to a first embodiment.

FIG. 2 is a plan view of the optical recording medium according to the first embodiment.

FIG. 3 is a view for explaining a wavelength and an amplitude of a wobble according to the first embodiment.

FIG. 4 is a diagram illustrating bi-phase modulation when recording address information.

FIG. 5 is a diagram illustrating a method of recording an address of a magneto-optical recording medium according to the first embodiment.

FIG. 6 is a diagram showing an address format of the magneto-optical recording medium of the present invention.

FIG. 7 is another plan view of the optical recording medium according to the first embodiment.

FIG. 8 is still another plan view of the optical recording medium according to the first embodiment.

FIG. 9 is still another plan view of the optical recording medium according to the first embodiment.

FIG. 10 is still another plan view of the optical recording medium according to the first embodiment.

FIG. 11 is a block diagram of an optical reproducing apparatus according to the first embodiment.

FIG. 12 is a diagram illustrating detection of a wobble in which a data area is formed.

FIG. 13 is a timing chart illustrating an operation of a PLL circuit.

FIG. 14 is another diagram illustrating detection of a wobble in which a data area is formed.

FIG. 15 is a diagram showing a planar structure of a conventional optical recording medium.

FIG. 16 is an optical recording medium cutting apparatus according to the present invention.

FIG. 17 is another cutting device of the optical recording medium according to the present invention.

FIG. 18 is still another cutting device for an optical recording medium according to the present invention.

FIG. 19 is a diagram showing the relationship between wobble length and crosstalk of an optical recording medium according to the present invention.

FIG. 20 is a diagram showing a relationship between wobble length and crosstalk of a conventional optical recording medium.

FIG. 21 is a diagram showing a relationship between crosstalk and an error rate of a conventional optical recording medium.

FIG. 22 is a plan view of an optical recording medium according to a second embodiment.

FIG. 23 is a diagram illustrating the difference in the waveform of a reproduction signal depending on the irradiation position of a laser beam.

FIG. 24 is a diagram illustrating a method for removing leakage into a reproduced signal according to the third embodiment.

FIG. 25 is a block diagram of an optical reproducing device according to a third embodiment.

FIG. 26 is a diagram illustrating an example of a tracking correction circuit.

FIG. 27 is a diagram illustrating another example of the tracking correction circuit.

FIG. 28 is a diagram showing a planar structure of a magneto-optical recording medium according to a third embodiment.

FIG. 29 is a block diagram of an erase circuit according to Example 2 in the third embodiment.

FIG. 30 is a diagram illustrating signals according to Example 2 in the third embodiment.

FIG. 31 is a diagram illustrating an erase circuit according to a third example of the third embodiment.

FIG. 32 is a diagram illustrating a relationship between an error rate of a reproduction signal and a correction amount according to Example 3 in the third embodiment.

FIG. 33 is a diagram showing another planar structure of the magneto-optical recording medium according to the third embodiment.

FIG. 34 is a block diagram of an erase circuit according to Example 4 of the third embodiment.

FIG. 35 is a diagram illustrating signals according to Example 4 in the third embodiment.

FIG. 36 is a block diagram of an erase circuit according to Example 4 in the third embodiment.

FIG. 37 is a diagram illustrating signals according to Example 5 in the third embodiment.

FIG. 38 is a diagram illustrating signals for explaining signal processing according to Example 6 in the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Magnetic film 3, 31, 32, 33 ... Groove 4, 41, 42 ... Land 5, 6, 8, 9, 44, 45, 51, 52, 53, 5
4, 55, 56, 57, 58 ... wobble 10 ... optical recording medium 110 ... spindle motor 111 ... servo circuit 112 ... optical head 113 ... photodetector 114 ... reproduction Signal amplification circuit 118: signal demodulation circuit 115: wobble detection circuit 116: address detection circuit 117: PLL circuit 119: laser drive circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G11B 20/10 321 G11B 20/10 321Z 351 351Z (72) Inventor Satoshi Sumi 2 Keihanhondori, Moriguchi-shi, Osaka 5-5-5 Sanyo Electric Co., Ltd. (72) Inventor Koji Uchihara 2-5-5 Sanyo Electric Co., Ltd., Sanyo Electric Co., Ltd. (72) Inventor Kenji Asano Keihan Moriguchi, Osaka 2-5-5 Hondori Sanyo Electric Co., Ltd. (72) Inventor Noboru Mamiya 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Kenji Tanase Moriguchi, Osaka Sanyo Electric Co., Ltd. 2-5-2-5, Keihanhondori-shi, Sanyo (72) Inventor Sayoko Tanaka 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Person Takahisa Suzuki 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Shigeki Hori 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72 ) Inventor Toshiaki Hioki 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hisashi Matsuyama 2-5-5 Keihanhondori, Moriguchi-shi Osaka (72) Inventor Yoshihiro Hori 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5D029 WA03 WD16 5D044 BC02 CC04 DE38 DE57 DE58 FG09 FG19 GM02 GM12 5D075 CC23 DD05 DD06 5D090 AA01 BB10 CC04 CC14 DD01 DD05 EE15 FF07 FF45 GG03 GG28

Claims (4)

[Claims] 1. An optical recording medium comprising a land and a groove, wherein a wobble whose width of the groove changes at a predetermined cycle with respect to the traveling direction of the laser beam is provided on a wall on both sides of the groove in the signal recording area. A synchronizing signal generation circuit for generating a synchronizing signal from the wobble reproduction signal; and an optical unit for reproducing a signal in the signal recording area based on the synchronizing signal generated by the synchronizing signal generation circuit. And an optical reproduction device. 2. The groove in the signal recording area, comprising lands and grooves, includes wobbles provided on both side walls so that the width of the groove changes at a predetermined cycle in the traveling direction of the laser beam, The groove of the address area is an optical reproducing apparatus for reproducing an optical recording medium including wobbles of the same phase on both sides of the wall, wherein a synchronization signal is obtained from a reproduction signal of the wobble provided on the wall of the groove of the signal recording area. An optical reproducing apparatus, comprising: a synchronizing signal generating circuit for generating; and an optical unit for reproducing a signal in the signal recording area based on the synchronizing signal generated by the synchronizing signal generating circuit. 3. The groove in the signal recording area includes wobbles provided on both sides of the signal recording area such that the width of the groove changes at a predetermined period in the traveling direction of the laser beam. An optical reproducing apparatus for reproducing an optical recording medium including another wobble of a predetermined period on at least one wall of the groove of the address area, wherein a reproduction signal of a wobble provided on a wall of the groove of the signal recording area An optical reproducing apparatus, comprising: a synchronizing signal generation circuit that generates a synchronizing signal from the optical disk; and an optical unit that reproduces a signal in the signal recording area based on the synchronizing signal generated by the synchronizing signal generating circuit. 4. The optical reproducing apparatus according to claim 1, further comprising an address detection circuit for detecting address information from a wobble reproduction signal provided in the address area.
The optical reproducing device according to any one of the above items.