JPH10124947A - Optical disk and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stably read of an address signal even at a narrow track pitch. SOLUTION: Prepits 14a-14e and 15a-15e are formed in lands 14 and 15 positioned between grooves 11-13 on this magneto-optical disk 10. These prepits 14a-14e and 15a-15e are formed in a sector mark pattern. An area to be recorded with the address signal (VFO, AM and ID, etc.) other than the sector mark is secured in an MO signal area (so-called magnetic field modulation recording area). Consequently, the address signal other than the sector mark can be recorded by the MO signal (in magnetic field modulation recording). As a result, even when the recording density is increased, the address signal can stably be read out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk and a method for manufacturing an optical disk, and more particularly to an optical disk capable of recording information such as a magneto-optical disk and a method for manufacturing such an optical disk.

[0002]

2. Description of the Related Art Writing information using a laser beam,
One type of rewritable optical disk that can be erased and read is a magneto-optical disk. The format of this magneto-optical disk is ISO (International
l Organization for Standardization).

FIG. 10 is a diagram showing a sector format corresponding to 1024 bytes / sector. FIG. 11 is a diagram showing a sector format corresponding to 512 bytes / sector. In either format,
In one sector format 110, 120, preformat header sections 111, 121, ALPC (Au
to Laser Power Control) & Gaps section 112,12
2, the data units 113 and 123, and the buffer unit 114,
124 are provided. Preformat header part 1
Preformatted address pits (emboss pits) are provided in 11, 121. The address signal is reproduced by reading the address pits. The address signal includes a sector mark (SM), a synchronization signal pattern (VFO: Variable Frequency Osillato).
r), address mark (AM), identification data (ID),
And postamble data (PA).

[0004] Among such formats, FIG.
The sector format 110 corresponding to 1024 bytes / sector is suitable as a CS system (continuous groove servo system). Then, on the land recording type magneto-optical disk, information according to the sector format is provided between the grooves (guide grooves).

FIG. 12 is a diagram showing a sector layout pattern of a conventional land recording system. As shown in the figure,
Grooves 131 to 133 are formed at track pitch intervals (track pitch: 1.1 to 1.6 μm). The lands 134 and 135 between the grooves 131 to 133
Are provided with header areas 134a and 135a and user areas (data areas) 134b and 135b. In the header areas 134a and 135a, pits indicating information of the preformat header section 111 of the sector format 110 are preformatted in advance. The user areas 134b and 135b are information recording areas by magnetic field modulation recording. Then, by irradiating the user regions 134b and 135b with laser beams along the grooves 131 to 133, it is possible to perform operations such as recording and reproduction while continuously applying tracking servo.

FIG. 12 shows a land recording system, but there is a groove recording system as another recording system. FIG.
FIG. 3 is a diagram showing a sector layout pattern of a conventional groove recording method. In the groove recording method, the grooves 151 and 152 also serve as a user area (data area). Prepits 153 and 154 for addresses are formed on the same radius (track) as the grooves 151 and 152. The pre-pits 153 and 154 and the grooves 151 and 15 are
2 has the same depth, and each section has a trapezoidal shape.

[0007]

However, according to the land recording method as described above, in the mastering step,
The address pits are formed as pre-pits at the center of the land, and the address pits are sandwiched between the grooves. Therefore, there is a problem that the degree of pit modulation is lower than when there is no groove. As the degree of modulation decreases, errors in reading the signal increase.

Particularly, in the case of pits of the VFO signal, since the pits are recorded in a fine pattern, the degree of pit modulation is smaller than the degree of modulation of an address marker or the like. That is, when a laser beam is irradiated during recording or reproduction, the ratio of the distribution of the amount of reflected light by the groove to the distribution of the amount of reflected light by the VFO signal pits increases. As a result, the modulation degree of the VFO signal pit itself becomes relatively small. This decrease in the modulation degree becomes more remarkable when the track pitch becomes narrower, and becomes more remarkable when the linear density is increased for higher density.

In addition, although a channel clock is generated by address pits, such a reduction in the degree of pit modulation causes a serious problem that the channel clock cannot be reproduced. In particular, since the VFO signal is a reference signal for recording / reproducing, if the modulation degree of the VFO signal does not satisfy a prescribed signal amount, a recording / reproducing system cannot be established.

Further, in the groove recording method proposed so far, the depth of the pre-pit and the groove is the same, but the depth at which the respective modulation degrees of the servo signal of the groove and the signal of the pit become maximum. Therefore, if the depth is determined so as to maximize the degree of modulation of the groove, the degree of modulation in the pit must be reduced. On the other hand, the linear density is lower than the MTF (Modulation Transfer) of the optical pickup.
Function) It has been studied to use a region beyond the limit (Irista and PRML: Partial Response Max)
imum Likelihood etc.). In order to perform the design near the limit of the linear density as described above, it is necessary to design such that the modulation degree in the pit portion is prevented from lowering as much as possible.

As described above, when the recording density is increased, it is known that the quality of the signal recorded by the emboss pit is lower than that of the MO signal. In an optical disk having a low address error rate, the number of exchanged sectors increases, resulting in a decrease in storage capacity.

The present invention has been made in view of such a point, and an object of the present invention is to provide an optical disk capable of stably reading an address signal even with a narrow track pitch.

[0013]

According to the present invention, in order to solve the above-mentioned problems, a pit indicating a signal of a sector mark is preformatted on an optical disk on which information can be written, and an address signal other than the sector mark is transmitted. The area to be recorded was secured in the magnetic recording area,
An optical disc having a header section for each sector is provided.

According to this optical disk, an address signal other than a sector mark can be magnetically recorded. If the sector mark signal is pre-formatted with pits and the address signals other than the sector mark are recorded by magnetism, when reproducing those signals, the sector mark signal and the address signal other than the sector mark are separated from the channel. Is output to For this reason, the recognition rate of the sector mark is improved, and the address signal other than the sector mark can be reliably read as a magnetic signal.

In the method of manufacturing an information writable optical disk in which header information is preformatted, a pit indicating a signal of a sector mark is preformatted in a header portion of each sector, and a pit indicating a signal of a sector mark is pre-formatted. In an optical disc in which an address area for recording the address signal is secured in a magnetic recording area, an address signal other than the sector mark is magnetically recorded in the address area in a certifying step. An optical disk manufacturing method is provided.

According to such an optical disk manufacturing method, the address signal other than the sector mark is recorded in the certifying process. Therefore, the recording of the address signal other than the sector mark before the shipment of the optical disk product is performed without increasing the number of working steps. Becomes possible.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, a magneto-optical (MO) disk is used as an information writable optical disk.

FIG. 1 is a diagram showing a layout pattern according to the first embodiment of the present invention. In the magneto-optical disk 10 to which the present invention is applied, the pre-pits 14a to 14e, 15a are provided on the lands 14, 15 between the grooves 11 to 13.
15e are formed. These pre-pits 14a
To 14e, 15a to 15e form a sector mark pattern. An area where an address signal (header information other than a sector mark such as VFO, AM, ID, etc.) is to be recorded is an MO signal area (an area for performing so-called magnetic field modulation recording).
Is secured.

As described above, since only the sector mark is constituted by the prepits 14a to 14e and 15a to 15e, and the area for recording the address signal other than the sector mark is provided in the MO signal area, the address signal is recorded by the MO signal ( Magnetic field modulation recording). As a result, the address signal can be read stably even when the recording density is increased.

When recording and reproducing data, the address is always reproduced before reading or writing the data. At this time, the sector mark is used to find the head of the address. Generally, the sector mark uses a pattern that does not exist in the modulation code to be used.

The address signal is transmitted to the magneto-optical disk 1
Write 0 in the MO signal area before shipping as a product.
This writing of the address signal can be performed in an overall quality inspection step called certification. This certification step is a step performed by most manufacturers that manufacture magneto-optical disks before shipping. Therefore, if address signals are written in the certification step, there is no cost burden.

Hereinafter, the characteristics of the signal when the signal of the header portion of the magneto-optical disk of the present invention is read will be described. FIG. 2 shows the recording / recording of information on the magneto-optical disk
FIG. 2 is a schematic configuration diagram of a magneto-optical disk device that performs reproduction. The magneto-optical disk 10 is fixed to a rotating shaft of a spindle motor 21. The magneto-optical disk 10 is rotated by the spindle motor 21 rotating the shaft at a constant rotation speed according to the rotation speed control signal.

Recording and reproduction of data on the magneto-optical disk 10 are performed by an optical pickup 22 and a magnetic head 23. During reproduction, the optical pickup 22 irradiates the magnetic disk 10 with a laser beam and observes the reflected light to determine the magnetization direction of the magnetic material of the magnetic disk 10. At the time of recording, a position where information is to be recorded is irradiated with a laser beam to raise the temperature of the magnetic body to the Curie temperature.

The magnetic head 23 includes a magnetic head driving circuit 24
A magnetic field is generated in a portion irradiated with a laser beam during data recording to perform magnetic modulation recording.
The laser output of the optical pickup 22 is controlled by a laser power control circuit 25.

The reproduced signal output from the optical pickup 22 is sent to a signal processing circuit 26. Signal processing circuit 2
Numeral 6 has a PLL circuit and a modulation / demodulation circuit, and generates a channel clock and a magnetic head driving circuit 24 for recording signals.
Output to

The linear motor 27 moves a carriage (not shown) on which the optical pickup 22 and the magnetic head 23 are mounted to a target track according to a slide signal.

The servo control circuit 28 includes the optical pickup 22
, A tracking error signal, a tracking error signal, a tracking driving signal, and a focus driving signal. Focus and tracking control is performed using these signals. That is, a slide signal is output to the linear motor 27 and a rotation speed control signal is output to the spindle motor 21.

The system controller 29 controls the operations of the laser power control circuit 25, the signal processing circuit 26, and the servo control circuit 28. Then, an error correction code is added to the data to be recorded, and errors are detected and corrected using the error correction code during reproduction.

FIG. 3 is a diagram showing an optical system of the optical pickup. In the drawing, light emitted from a laser diode 22a is collimated by a collimator lens 22b, a shaping prism 22c, a beam splitter 22d, a deflection beam splitter 22e,
And passes through the objective lens 22f to focus on the magneto-optical disk 10. The reflected light from the magneto-optical disk 10 passes through an objective lens 22f and is deflected by a deflecting beam splitter 22e.
Divided.

The light that has traveled straight through the deflection beam splitter 22e is reflected by the beam splitter 22d and is input to the photodiode 22g. The photodiode 22g converts the received light into an electric signal and outputs it as a tracking signal.

The light reflected by the deflecting beam splitter 22e passes through a half-wave plate 22h and a phase compensating plate 22i and is split into two by a deflecting beam splitter 22j. The light reflected by the deflection beam splitter 22j is
k. The photodiode 22k converts the received light into an electric signal and inputs the electric signal to the amplifiers 22n and 22o. Light traveling straight through the deflection beam splitter 22j is input to the photodiode 22m. The photodiode 22m converts the received light into an electric signal,
2n, 22o.

The amplifier 22n includes a photodiode 22k
And the sum of the signal from the photodiode 22m and the sum signal is input to the first channel (CH.1). On the other hand, the amplifier 22o is connected to the photodiode 2
The difference between the signal from 2k and the signal from the photodiode 22m is taken, and the difference signal is sent to the second channel (CH.
Enter in 2). The sum signal output from the amplifier 22n is a signal indicating the presence or absence of a pit on the magneto-optical disk 10. The difference signal output from the amplifier 22o is an MO signal detected by the Kerr effect.

With the above-described magneto-optical disk drive,
When the data on the magneto-optical disk 10 shown in FIG. 1 is reproduced, only the sector mark signal is output from the first channel (CH.1). From the second channel (CH.2), an address signal other than a sector mark signal such as a VFO signal and a data area signal are output.

The sector mark pattern is formed as a long pattern that does not meet the running length limit RLL (1, 7). FIG. 4 is a diagram showing a sector mark pattern. In the figure, the upper side shows sector mark patterns of odd-numbered bands, and the lower side shows sector mark patterns of even-numbered bands. In this figure, the bit period is represented by T. As shown in the figure, the sector mark pattern includes a long mark pattern portion in which a 6T bit sequence and a 12T bit sequence are alternately repeated, and a 6-bit lead-in portion (Lead-In).

FIG. 5 is a diagram showing a VFO field pattern. "VFO1", "VFO1"
2 and “VFO3” are shown. The VFO signal consists of 3 bits of 2-bit data.
Converted to channel bits. Therefore, "VFO
"1" has been converted to 312 channel bits and "V
FO2 "has been converted to 192 channel bits,
“VFO3” is converted into 324 channel bits.

As can be seen from a comparison between FIG. 4 and FIG. 5, the sector mark pattern has a longer pattern than the VFO field pattern. Next, the definition of each signal will be described. FIG. 6 is a diagram showing the definition of the tracking signal. This is the ISO (International Organization for Standardization) / IE
This is the definition of the tracking signal in the C (International Electrotechnical Commission) 15041 standard. The beam-irradiated portion 31 of the photodiode 30 is divided into two regions 31a and 31b, and the signals are I ₁ and I ₂ . Then
The push-pull signal is as follows: push-pull signal = (I ₁ −I ₂ ) _PP / (I ₁ + I ₂ )
_OL , and the cross-track signal is: cross-track signal = (I ₁ + I ₂ ) _PP / (I ₁ +
I ₂ ) _OL . Here, (I ₁ + I ₂ ) _OL indicates a reflected signal on the land, and (I ₁ + I ₂ ) _PP indicates a sum signal (I ₁ + I ₂ ).
₂ ) shows the difference (Peak-to-Peak) between the upper and lower limits of (I) and (I)
₁ -I _{2) PP} represents the difference between the upper and lower limits of the differential signal _{(I 1 -I 2) (Peak} -to-Peak).

FIG. 7 is a diagram showing the definition of a header signal. This is the definition of the header signal in the ISO / IEC15041 standard. In the figure, I _OL is a beam output on a groove on which no data is written, I _sm is a signal in the sector mark area 32, I _vfo is a signal in the VFO area 33, and I _P is an AM, ID, PA area 34. Signal.

The definition shown in FIG. 7 is a definition for obtaining the modulation degree of the signal in each area when all the header signals are preformatted. Magneto-optical disk 1 of the present invention
0, only the sector mark is pre-formatted, so that only the signal in the sector mark area 32 is the first signal.
Is input to the channel (CH. 1) of the VFO area 33.
Subsequent signals are not input to the first channel (CH.1). That is, the area other than the sector mark becomes a DC signal. Therefore, the possibility of misidentifying a signal other than the sector mark as a sector mark is reduced.

When there is a defect on the sector mark, a slightly different signal is detected even when the sector mark is read. At this time, even if the read pattern does not completely match the specified pattern, it is generally recognized as a sector mark if it matches at least to some extent. According to the magneto-optical disk of the present invention, as described above, it is unlikely that a signal such as a defect other than a sector mark is erroneously recognized as a sector mark. Becomes Reducing the matching rate for recognition as a sector mark improves the recognition rate of the sector mark.

In the current magneto-optical disk, if a sector mark cannot be detected, the sector is not used, and an area of one sector cannot be used due to a defect of about several bytes. Therefore, the improvement in the recognition rate of the sector mark leads to effective use of the data storage area in the disk.

On the other hand, the second channel (C
H. In 2), the signal recorded on the MO film enters.
These signals are a header part and a data part other than the sector mark. Since the reading of the MO signal is not related to the decrease in the pit modulation degree, the address signal other than the sector mark can be correctly read even if the linear density is increased.
As a result, even if the linear density is improved, the channel clock can be reproduced stably. For example, the magneto-optical disk of the present invention can be applied to an optical disk system in which the track pitch is 0.8 μm or less and the wavelength of the optical pickup is 680 nm or more.

Further, if data is recorded in the ALPC and Gap portions, the channel clock can be continuously reproduced, which is effective for surely reproducing the channel clock. If the compatibility of the sector format is neglected, the ALPC, Gap and VFO3 parts can be deleted. This increases the storage capacity by 3.1% for 1024 bytes / sector and 5.6% for 512 bytes / sector.

In the first embodiment, the grooves of the continuous grooves are provided on both sides of the sector mark.
This groove can be removed or replaced with a pit having the same function as the groove.

FIG. 8 is a diagram showing a layout pattern according to the second embodiment of the present invention. In this embodiment, the grooves 41 to 43 are provided only on both sides of the MO signal area (the area of the address signal other than the sector mark and the data area).
Are formed, and the land 4 is located between the grooves 41 to 43.
4, 45 are provided. Prepits 44a, 45a of a sector mark pattern are formed on the lands 44, 45, and a groove is not provided in a region around the prepits 44a, 45a, so that a mirror surface 46 is formed.

As described above, by using the mirror surface 46 around the pre-pits 44a and 45a, the influence of the groove on the modulation of the sector mark pattern is eliminated.
FIG. 9 is a diagram showing a layout pattern according to the third embodiment of the present invention. In this embodiment, in the MO signal area (the area of the address signal other than the sector mark and the data area), continuous grooves 51 to 53 are formed on both sides of the lands 54 and 55, and the groove 51 is formed.
Lands 54 and 55 are provided between. On the lands 54 and 55, prepits 54a and 55a of a sector mark pattern are formed.
On both sides of the continuous grooves a and 55a, the pre-pits 51a, 52a and 53 having the same function as the grooves are formed instead of the grooves of the continuous grooves.
a is provided. These pre-pits 51a, 52
a and 53a are prepits 5 of the sector mark pattern.
Patterns synchronized with 4a and 55a are formed.

As described above, since the prepits 51a, 52a, 53a having the same function as the groove are provided on both sides of the prepits 54, 55a of the sector mark pattern, the modulation of the sector mark can be performed more than in the case of the groove of the continuous groove. The degree can be improved.

Although the above embodiment is of a land recording type, the present invention can be applied to a magneto-optical disk of a groove recording type. In this case, in the header areas 153 and 154 shown in FIG. 13, only sector marks are formed by prepits, and address signals other than the sector marks are recorded by magnetic field modulation recording. As a result, even if the line density is increased, an address signal other than a sector mark such as a VFO signal can be reliably read as an MO signal. Therefore, as in the case of the land recording method, the recognition rate of the sector mark can be improved, and the VFO signal and the like can be read reliably and the channel clock can be reproduced stably.

[0048]

As described above, in the optical disk of the present invention, the pits indicating the signal of the sector mark are pre-formatted, and the area for recording the address signal other than the sector mark is secured in the magnetic recording film. Address signals such as VFOs other than marks can be magnetically recorded, and address signals can be stably read even if the recording density is increased.

Further, according to the optical disk manufacturing method of the present invention,
Since the address signal other than the sector mark is recorded in the certification step, the address signal can be magnetically recorded without increasing the number of optical disc manufacturing steps.

[Brief description of the drawings]

FIG. 1 is a diagram showing a layout pattern according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a magneto-optical disk device for recording / reproducing information on / from a magneto-optical disk according to the present invention.

FIG. 3 is a diagram showing an optical system of the optical pickup.

FIG. 4 is a diagram showing a sector mark pattern.

FIG. 5 is a diagram showing a VFO field pattern.

FIG. 6 is a diagram showing a definition of a tracking signal.

FIG. 7 is a diagram showing a definition of a header signal.

FIG. 8 is a diagram showing a layout pattern according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a layout pattern according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a sector format corresponding to 1024 bytes / sector.

FIG. 11 is a diagram showing a sector format corresponding to 512 bytes / sector.

FIG. 12 is a diagram showing a sector layout pattern of a conventional land recording method.

FIG. 13 is a diagram showing a sector layout pattern of a conventional groove recording method.

[Explanation of symbols]

10 ... magneto-optical disk, 11-13 ... groove, 14, 15 ... land, 14a-14e, 15a
~ 15e ... Pre-pit.

Claims (4)

[Claims] 1. A rewritable optical disk, wherein pits indicating sector mark signals are preformatted, and an area for recording an address signal other than the sector mark is secured in a magnetic recording area. An optical disc having a header section for each sector. 2. The semiconductor device according to claim 1, further comprising guide grooves provided on both sides of the header except for the periphery of a pit indicating the signal of the sector mark, and on both sides of a data area on the same track as the header. The optical disk according to claim 1, wherein 3. A pre-pit provided on both sides of a pit indicating the signal of the sector mark and synchronized with the pit indicating the signal of the sector mark, and both sides of an area for recording an address signal other than the sector mark. 2. The optical disk according to claim 1, further comprising: a guide groove provided on both sides of a data area on the same track as the header section. 4. A method for manufacturing an information writable optical disk in which header information is formatted in advance, wherein a pit indicating a signal of a sector mark is preformatted in a header portion for each sector, and a pit indicating a signal other than the sector mark is provided. In an optical disk in which an address area for recording the address signal is secured in a magnetic recording area, an address signal other than the sector mark is magnetically recorded in the address area in a certifying step. An optical disc manufacturing method.