JPH10312563A - Information recording and reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a tracking shift because of a tilt, etc., by generating an offset signal having a predetermined code on the basis of a comparison result between a first amplitude and a second amplitude, moving an objective lens based on the offset signal, and controlling a laser light based on a corrected tracking signal. SOLUTION: A phase comparison circuit 67 detects a first amplitude and a second amplitude from a detected wobble signal, and compares to see which of the amplitudes is larger. When the first amplitude is larger than the second amplitude, a first offset signal is generated. When the first amplitude is smaller than the second amplitude, a second offset signal of an opposite code of that of the first offset signal is generated. When the first amplitude is almost equal to the second amplitude, a tracking signal is generated. These signals are sent to a servo circuit 66. The servo circuit 66 controls to move an objective lens in an optical head 61 in accordance with the first or the second offset signal when receiving the offset signal, and then sends a reproduction signal at a new tracking position to the phase comparison circuit 67.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing apparatus for an optical recording medium capable of recording or reproducing at high density.

[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 walls of the groove. Then, the wobble formed in the data area is reproduced, and a synchronizing signal for recording or reproducing a signal is generated from the reproduced wobble signal.

[0003] As such a magneto-optical recording medium, in Japanese Patent Application No. 76199/1997, a wobble having a different waveform is provided on both sides of the groove of the address area and the data area, and the wobble of the data area is provided. The waveform discloses a magneto-optical recording medium having a structure in which one wobble waveform and the other wobble waveform of a groove have opposite phases.

[0004]

Tracking to a land or a groove of a magneto-optical recording medium is performed by push-pull. The tracking by push-pull will be described with reference to FIGS. On opposite sides of the groove 20, wobbles 24 having opposite phases are provided.
1 and 242 are provided, and when tracking is performed at the center of the groove indicated by the straight line 60, the laser beam is applied to the position indicated by the spot 63. Photodetector 120 in optical means for detecting reflected light from signal recording surface
Indicates that the direction indicated by the arrow 121 is the track direction, and the arrow 1
It is arranged so that the direction indicated by 22 is the tracking direction, and is divided into four regions A, B, C, and D.
When the laser light is applied to the position indicated by the spot 63 in FIG. 8, the light detector 120 is irradiated with the spot 123. In the push-pull method, each area A, B, C, D
The light intensities detected in the above are DA, DB, DC, and D, respectively.
When D is set, tracking is performed by controlling (DA + DB)-(DC + DD) to be zero.

[0005] However, the laser beam irradiated on the signal recording surface due to the tilt of the substrate of the magneto-optical recording medium may be tracked at a position indicated by a straight line 61 shifted from the center of the groove 20. That is, when the light is irradiated on the position indicated by the spot 64 in FIG. 8, the spot 124 is irradiated on the photodetector 120, and the laser light is shifted in the direction of the arrow 122. In this case, the area of the reflected light applied to each of the regions A and B is larger than the area of the reflected light applied to the regions C and D, but the light intensity is (DA + DB) − (DC
+ DD) is zero. This is because the areas A and B
The reflected light from the adjacent land (not shown) beyond the wobble 241 in FIG. 8 is also irradiated. Therefore, the light intensity is higher than the intensity of the reflected light applied to the regions C and D including only the reflected light from the groove. Because it becomes weak.

Accordingly, when tracking is performed by the push-pull method, tracking is performed at a position deviated from the center of the groove due to tilt, and there is a possibility that recording or reproduction of a signal on the magneto-optical recording medium cannot be performed accurately. An object of the present invention is to provide an information recording / reproducing apparatus which solves such a problem and removes a tracking deviation due to a tilt or the like to accurately record or reproduce a signal.

[0007]

The invention according to claim 1 is
An information recording / reproducing apparatus for a recordable and / or reproducible recording medium including a calibration area including lands and grooves and having wobbles of the same phase provided on both side walls of the groove, wherein a laser beam is applied to the calibration area. Optical means for irradiating and detecting the reflected light; input of a reproduction signal detected by the optical means; a first amplitude of a reproduction waveform at a first timing and a predetermined interval with respect to the first timing; The second amplitude of the reproduced waveform at the second timing shifted by the second amplitude is detected, and the first amplitude>
If it is the second amplitude, a first offset signal is generated,
If the first amplitude is smaller than the second amplitude, a second offset signal having the opposite sign to the first offset signal is generated. If the first amplitude is approximately equal to the second amplitude, the corrected tracking signal is generated. And an objective lens in the optical means is moved based on the first and second offset signals from the phase comparison circuit, and the center of the land or groove is calculated based on the corrected tracking signal. And a servo circuit for controlling the laser beam.

Further, the invention according to claim 2 further includes a first
The predetermined interval between the timing of (1) and the second timing is an interval corresponding to a half of the wavelength of the wobble provided in the calibration area. The invention according to the claim is further characterized by an information recording / reproducing apparatus for a recording medium including an address area in which wobbles having the same phase are provided on both side walls of the groove.

The invention according to claim 4 is further characterized in that the information recording / reproducing apparatus for a recording medium includes a data area in which wobbles having opposite phases are provided on both side walls of the groove. The invention according to claim 5 further includes:
An information recording / reproducing apparatus for a recording medium including an address area in which wobbles having the same phase are provided on walls on both sides of the groove and a data area in which wobbles having opposite phases are provided on walls on both sides of the groove. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 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 an example of a plan view of a magneto-optical recording medium 10 to which the present invention is applied. The magneto-optical recording medium 10 has TO
C area, and the data area 3 includes a plurality of zones 31,.
.. divided into 3n. Each zone 31, ...,
At 3n, the angular velocity of the magneto-optical recording medium 10 is constant.

The land / groove structure of the data area 3 will be described with reference to FIG. Data area 3 is
An address section 23 is provided following the calibration section 50, a data section 24 is provided following the address section 23, and an address section 25 is provided following the data section 24. That is, the address portion and the data portion are repeatedly formed as a set. Address part 23, 25
Is 96 data bytes long, and the data section 24 is 2754
Data byte length. In addition, wobbles 231 and 232 having the same phase are provided on the walls on both sides of the grooves 20 and 22 in the address portions 23 and 25, and wobbles 241 and 242 having the opposite phases are provided in the data portion. Further, in the calibration unit 50, the wobbles 51, 5 having the same phase but different from the wobbles 231 and 232 are used.
2 are provided. As a result, the calibration unit 50, the address units 23,
5, the wobbles 51, 52, 232, and 231 have the same phase.
However, in the data section 24, wobbles 242 and 241 having opposite phases
Is formed.

Referring to FIG. 3, details of wobbles 241 and 242 of opposite phases provided in data section 24 will be described. The amplitude 30 of the wobble 241 is peak to
The peak is 30 (allowable range: 5 to 60) nm, and the interval 32 between the center of the groove 20 and the center of the land 21 is:
0.6 (allowable range: 0.2 to 1.0) μm. The amplitude of the wobble 242 is the same as that of the wobble 241.
The wavelength 33 of the wobbles 241 and 242 is 1.88 μ.
m. When recording a magneto-optical signal, the wavelength is 1.8.
An 8-bit signal is recorded in 8 μm. Therefore, the length of one bit is 0.235 μm / bit. In the magneto-optical recording medium to which the present invention is applied, the wavelength 33 of the wobbles 241 and 242 may be in the range of 1.5 to 60 μm.

Referring to FIG. 4, the addresses 23, 25
Will be described in detail. The address section 23 has an area having a length of 96 data bytes, and has a data amount of 96 bits. That is, the length of one bit of the address part is eight times the recording bit, and for example, the bit length of the recording bit is 0.2.
When it is 2 μm, the length of the data bit of the address part is equivalent to 1.76 μm. The configuration of the address section 23 is 6 data bytes long as the preamble (PA) 91, 42 data bytes long as the address 1 (Address 1), 2 data bytes long as the Reserved 96, 42 data byte length as the address 2 (Address 2), and A 2 data bytes length as pattern 101,
The address mark (AM) 102 is 2 data bytes long. The address 1 (Address 1) has 4 bits as the first synchronization signal (SYNC 1) 92, 8 bits as the frame address (Frame address) 93, and the track address (Track address).
ess) 16 bits as 94, 14 as CRC95
Consists of bits. Address 2 (Address 2)
4 bits as the second synchronization signal (SYNC2) 97, bits as the frame address (Frame address) 98, and the track address (Track addr)
ess) 16 bits as 99, 1 as CRC100
It consists of 4 bits.

The wobbles 241 and 242 provided on the walls on both sides of the grooves 20 and 22 of the data section 24 of the magneto-optical recording medium shown in FIG. 2 synchronize with each other in recording or reproducing a signal on the magneto-optical recording medium. Used to generate a signal. This point is described in detail in Japanese Patent Application No. 76199, filed by the applicant of the present invention. Also,
The cross-sectional structure of the magneto-optical recording medium to which the present invention is applied is a structure in which a magnetic film is formed on a light-transmitting substrate such as polycarbonate or glass. The magnetic film includes a reproducing layer made of GdFeCo or the like and a recording layer made of TbFeCo or the like.

The details of the present invention will be described with reference to FIGS. The present invention is characterized in that the waveform shape of a reproduced signal obtained by reproducing the magneto-optical signal recorded in the calibration section is determined, and the tracking offset is corrected based on the determination result. Referring to FIG. 5, when the tracking is shifted to the upper side of the groove 20 on the paper, the magneto-optical signal is recorded in the hatched area 53 in the calibration section as shown in FIG. Is done. Accordingly, the reproduced waveform of the reproduced signal obtained by reproducing the magneto-optical signal recorded in this state has a waveform indicated by reference numeral 54. In this case, the amplitude of the reproduced waveform detected at the first timing A and the second timing B shifted from the first timing A by an interval corresponding to a half wavelength of the wavelengths of the wobbles 51 and 52. Are respectively the first amplitude,
Assuming the second amplitude, a relationship of first amplitude> second amplitude is established. Similarly, when the tracking is shifted to the lower side of the groove 20 on the paper surface, the magneto-optical signal is recorded in the hatched area 55 in FIG. The waveform shown by. In this case, the first amplitude is smaller than the second amplitude between the first amplitude detected at the first and second timings and the second amplitude.
Is established. Further, when tracking is performed at the center of the groove 20, a magneto-optical signal is recorded in the hatched area 57 of FIG. 5C, and the reproduced waveform thereof is a waveform indicated by reference numeral 58. In this case, a relationship of approximately the first amplitude = the second amplitude is established between the first amplitude and the second amplitude. Accordingly, when the relationship of the first amplitude> the second amplitude is established between the first amplitude and the second amplitude detected from the waveform of the reproduction signal of the magneto-optical signal, the tracking is performed on the paper by the arrow 59. A first offset signal is generated to shift the objective lens in the direction indicated by. When the relationship of the first amplitude <the second amplitude is satisfied, a second offset signal for shifting the tracking in the direction indicated by the arrow 60 on the paper is generated to move the objective lens. Further, when the relationship of approximately the first amplitude = the second amplitude is established, a tracking signal for tracking at that position is generated and tracking is performed.

Therefore, according to the present invention, the amplitude is detected at two predetermined timings from a reproduced waveform obtained by reproducing a magneto-optical signal,
The tracking offset is corrected based on the magnitude relationship between the two detected amplitudes. FIG. 6 shows a block diagram of an information recording / reproducing apparatus according to the present invention. The reflected light from the magneto-optical recording medium 10 is detected as a reproduction signal by a photodetector 62 in the optical head 61, and the detected reproduction signal is sent to a reproduction signal amplifier circuit 63 and amplified. Thereafter, the tracking error signal (TE) and the focus error signal (FE) of the reproduction signal are sent to the servo circuit 66, and the servo circuit 66 reads the tracking error signal and the focus error signal in the optical head 61 based on the sent tracking error signal and focus error signal. The tracking and focus servo of the objective lens not shown are performed.

The reproduction signal amplifying circuit 63 sends the wobble reproduction signals provided on both sides of the groove to the wobble detection circuit 64 and the address detection circuit 65 among the reproduction signals. The wobble detection circuit 64 detects a wobble signal from the received reproduction signal, and converts the detected wobble signal into a PL signal.
It is sent to the L circuit 68 and the phase comparison circuit 67. PLL circuit 68
Generates a synchronization signal in synchronization with the rise of the binarized signal by binarizing the sent wobble signal. The PLL circuit 68 sends the generated synchronization signal to the signal demodulation circuit 69 and the laser drive circuit 70. The signal demodulating circuit 69 synchronizes with the transmitted synchronizing signal to reproduce the magneto-optical signal (R
F) is demodulated and taken out as reproduction data. On the other hand, the laser drive circuit 70 drives a semiconductor laser (not shown) in the optical head 61 in synchronization with the transmitted synchronization signal.

Further, the address detection circuit 65 detects address information from the transmitted wobble reproduction signal, and the detected address information is used for recording or reproducing a signal on the magneto-optical recording medium 10. . Further, the reproduction signal amplification circuit 63 sends the reproduction signal of the magneto-optical signal to the phase comparison circuit 67. From the wobble signal sent from the wobble detection circuit 64, the phase comparison circuit 67
And the second timing, the first amplitude, which is the amplitude of the reproduced signal at the first timing, from the waveform of the reproduced signal sent from the reproduced signal amplifying circuit 63, and the reproduced signal at the second timing And the second amplitude, which is the amplitude of Thereafter, the magnitude relationship between the first and second amplitudes is compared. If the relationship of first amplitude> second amplitude is satisfied, a first offset signal is generated, and the first amplitude <second amplitude is generated. When the relationship of amplitude is established, a second offset signal having the opposite sign to the first offset signal is generated, and when the relationship of approximately first amplitude = second amplitude is established, a tracking signal is generated. Then, these signals are sent to the servo circuit 66. When the first or second offset signal is sent, the servo circuit 66 controls the objective lens in the optical head 61 to move according to each offset signal. After the objective lens moves based on the first or second offset signal, the optical head 61 performs a recording operation at a new tracking position, and then a magneto-optical signal is detected from a photodetector 62 in the optical head 61. Then, the reproduction signal is sent to the phase comparison circuit 67 via the reproduction signal amplification circuit 63. The same operation as described above is performed in the phase comparison circuit 67. The above operation is repeated until the tracking signal is generated from the phase comparison circuit 67. When a tracking signal is sent, the servo circuit 66 controls the objective lens in the optical head 61 so as to perform tracking at that position.

FIG. 7 shows a flowchart for correcting the tracking offset. After the start, a margin is set in step S1, an offset value is initialized to “0” in step S2, and tracking is turned on in step S3. In step S4, a magneto-optical signal is recorded in the calibration unit. In step S5, the magneto-optical signal recorded in step S4 is reproduced, and the first amplitude SR, which is the amplitude of the reproduced waveform at the first timing, is reproduced.
F1 and a second amplitude SRF2, which is the amplitude of the reproduced waveform at the second timing, is detected.
Calculate F1. When the calculation result is positive, the arrow 5 in FIG.
A first offset signal (OFST-1) for shifting the tracking in the direction of 9 is generated, and the process returns to S4 to repeat the subsequent operation. On the other hand, if the calculation result is negative, the second offset signal ((O) having the opposite sign to the first offset signal for shifting the tracking in the direction of arrow 60 in FIG.
FST + 1), and returns to S4 to repeat the operation. This operation is repeated until SRF2-SRF1 becomes 0. In addition, the value of SRF2-SRF1 is not limited to 0, but may be any value close to 0. Specifically, -0.
It only has to be in the range of 1 to +0.1.

The operation of removing the tracking offset described above is usually performed once after the magneto-optical recording medium is mounted on the information recording / reproducing apparatus. For example, it may be performed for each zone. Considering that the tilt is likely to occur at the outer peripheral portion of the magneto-optical recording medium, the tilt may be performed once each at the inner peripheral portion and the outer peripheral portion.

In the above description, only tracking to a groove has been described, but it goes without saying that tracking to a land can be similarly performed.

[0022]

According to the present invention, in an information recording / reproducing apparatus for performing tracking control by a push-pull method,
Since the tracking can be corrected near the center of the groove or the land, the recording or reproduction of the signal on the magneto-optical recording medium can be accurately performed.

[Brief description of the drawings]

FIG. 1 is a plan view of a magneto-optical recording medium of the present invention.

FIG. 2 is a diagram showing a land / groove structure of a magneto-optical recording medium according to the present invention.

FIG. 3 shows the wavelength, amplitude and land of a wobble according to the present invention.
It is a figure explaining the distance between grooves.

FIG. 4 is a diagram showing an address format of the magneto-optical recording medium of the present invention.

FIG. 5 is a diagram showing a positional relationship between a tracking position and a groove.

FIG. 6 is a block diagram of an information recording / reproducing apparatus.

FIG. 7 is a flowchart for implementing the present invention.

FIG. 8 is a diagram illustrating a problem of a tracking method using a push-pull method.

FIG. 9 is a diagram illustrating reflected light applied to a photodetector when laser light is applied to the center of a groove.

FIG. 10 is a diagram illustrating reflected light applied to a photodetector when laser light is applied off the center of the groove.

[Explanation of symbols]

 1, 2,... TOC area 3,... Data area 31,..., 3n... Zone 10 ... magneto-optical recording medium 20, 22,. Address part 24 Data part 30 Amplitude 32 Land / groove distance 33 Wobble wavelength 53 Calibration part 60, 61, 62 Linear 63, 64, 65 ..Spots 59, 60... Arrows 51, 52, 231, 232... In-phase wobble 241, 242... Out-of-phase wobble 61. Optical head 62... Photodetector 63. Signal amplification circuit 64 Wobble detection circuit 65 Address detection circuit 66 Servo circuit 67 Phase comparison circuit 68 PLL circuit 69 Signal demodulation circuit 70 Laser drive Circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 11/10 556 G11B 11/10 556C

Claims (5)

[Claims] 1. An information recording / reproducing apparatus for a recordable and / or reproducible recording medium including a calibration area including a land and a groove and having wobbles of the same phase provided on both side walls of the groove, Optical means for irradiating the calibration area with laser light and detecting the reflected light; and a reproduction signal detected by the optical means,
And a second amplitude of the reproduced waveform at a second timing shifted by a predetermined interval from the first timing, and a first amplitude> If the amplitude is 2, the first offset signal is generated. If the first amplitude is smaller than the second amplitude, a second offset signal having the opposite sign to the first offset signal is generated. Is substantially equal to the second amplitude, a phase comparison circuit for generating a corrected tracking signal, and an objective in the optical means based on the first and second offset signals from the phase comparison circuit. An information recording / reproducing apparatus, comprising: a servo circuit that moves a lens and controls the laser beam at the center of the land or groove based on the corrected tracking signal. 2. The information recording / reproducing apparatus according to claim 1, wherein the predetermined interval is an interval corresponding to a half of a wavelength of a wobble provided in the calibration area. 3. The information recording / reproducing apparatus according to claim 1, wherein the recording medium further includes an address area in which wobbles having the same phase are provided on both side walls of the groove. 4. The information recording / reproducing apparatus according to claim 1, wherein the recording medium further includes a data area in which wobbles having phases opposite to each other are provided on walls on both sides of the groove. 5. The recording medium further includes an address area having wobbles having the same phase on both sides of the groove and a data area having wobbles having opposite phases on both sides of the groove. An information recording / reproducing apparatus according to claim 1.