JP2001084590A - Information recording and reproduction device and information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the read precision of tracks, sectors, etc., and to make stably recordable and reproducible data by reading address information by reproducing the reproduced signal of prepits which are previously formed on a medium and information which is previously recorded. SOLUTION: A track is divided into plural sectors and the head of each of the sectors is composed of a sensor mark for presetting, a VFO11, a magnetooptic sector mark 14 which is recorded with a magnetooptic signal through a gap part 13 by forming the low-order bit group 12 of track data, the high-order bit group 15 of the track data, a sector number 16, and a CRC code 17 as prepit information. Here, address information recorded with a magnetooptic signal, the sector mark, VFO14, the high-order bit group 15 of the track data, the sector number 16, and the CRC code 17 are recorded by reading the low-order bit group 12 of the track data formed of prepits and confirming the track position in the initialization process of the disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims at providing an information recording / reproducing apparatus and an information recording disk having a large recording capacity. More specifically, the present invention relates to an information recording / reproducing apparatus and an information recording apparatus having improved reading accuracy of track numbers and sector numbers. Regarding the medium.

[0002]

2. Description of the Related Art With the advent of the multimedia era, information recording devices used in general-purpose computers and the like must handle not only character information but also voice and image information. And D
Optical discs such as VDs are receiving attention.

On an optical disc, tracks sequentially numbered sequentially from the inner circumference (or outer circumference) are formed concentrically or spirally. Each track is
As shown in FIG. 3, the data is divided into a plurality of areas called sectors, and information recording and reproduction are performed for each sector.

At the head of each sector, as shown in FIG. 1, preformat information mainly composed of a sector mark, a VFO, an address mark, address data and a CRC (Cyclic Redundancy Check) code. Are formed as pre-pits. Address information is obtained by reading the pre-pits, and information is recorded in the data area of each sector or information in the data area is read based on the obtained address information. The sector mark is a data pattern indicating the beginning of a sector, and is a VFO (Variable Frequency Oscillator).
Is a code pattern for adjusting the timing when the address data located immediately after that is read. In the address data, data indicating the track number to which the sector to be read belongs and the sector number are recorded. C
The RC code is an error detection code for instantly detecting whether or not the address data read immediately before is correct, and is generated based on the track number and the sector number.

The pre-pits can be reproduced by changing the reflectivity when a light beam scans the substrate by previously forming irregularities on the substrate. Recording in the data area is performed by magneto-optical recording or phase change recording.

[0006]

By the way, in recent years, it is necessary to change the film configuration in order to increase the capacity of the medium, and the focus position that maximizes the signal amplitude of the prepit and the magneto-optical or phase change signal amplitude have to be changed. A shift occurs in the maximum focus position, which causes a problem that a high-quality magneto-optical signal and a pre-pit signal cannot be obtained simultaneously.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide an information recording / reproducing apparatus capable of stably recording / reproducing data with good reading accuracy of address information such as tracks and sectors. It is an object to provide an apparatus and an information recording medium.

[0008]

According to a first aspect of the present invention, there is provided an information recording / reproducing apparatus for reading address information by reproducing a reproduction signal of pre-pits previously formed on a medium and information pre-recorded. I will provide a.

According to a second aspect of the present invention, information is characterized in that prepits corresponding to a part of address information are previously formed on a medium, and an area for recording a part of the address information is provided. A recording medium is provided.

According to the present invention, an address signal is recorded in a medium initialization step. In this initialization step, a pre-pit corresponding to the lower bit of the track number formed in advance on the medium is formed, the position is confirmed while reading a part of the address information from the reproduction signal obtained from the pre-pit, and the position of the address signal is confirmed. Record some or all.

In the case of magneto-optical recording, the recording is performed by increasing the laser power and applying a magnetic field while the recording film is raised to a temperature higher than the Curie temperature. In the case of phase change recording, the laser power is increased to raise the temperature of the recording film above the Curie temperature. According to the present invention, since a part of the address information can be read from the pre-pit signal and the position can be confirmed, it is possible to perform magneto-optical recording or phase change recording by confirming that the track is located on a predetermined track due to a track groove or a track error defect. It is.

In a drive for initialization, the focus position is set so that the pre-pit signal is maximized, and in a normal recording / reproducing drive, the focus position can be adjusted to magneto-optical recording or a phase change signal. Further, since the area formed as the pre-pit is only the lower bits of the address signal, it is possible to increase the bit length. By taking such a method, it is possible to stably record the address signal without omission. In particular, in the method of recording / reproducing by miniaturizing the light spot using a near field using a solid immersion lens, the focus shift is large, so that the signal quality is more remarkably improved.

In the address signal, prepits are formed in a time series in accordance with sector marks, track numbers, sector numbers, and CRC data for checking whether reading is accurate. Further, a VFO pattern may be added for adjusting the address reading timing. The sector number is the same sign in adjacent tracks, and the track number is 2
A gray code can be obtained by expressing the hexadecimal track number by exclusive OR with the immediately preceding track number, that is, the inter-code distance between adjacent tracks becomes 1 and changes by one bit. The crosstalk between tracks can be reduced. On the other hand, the CRC code is determined by the cyclic code generator polynomial, and therefore becomes a completely different code between adjacent tracks. In particular, in an information recording disk in which a head slider on which a solid immersion lens is arranged and formed is levitated above the disk to perform recording / reproduction, crosstalk between adjacent tracks is large because evanescently coupled light is used. For this reason, it is effective to perform recording in an area where a groove is provided as in the data area.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. Example 1 In this example, a double-sided recording type magneto-optical disk 100 as shown in the upper part of FIG. 2 was manufactured. As shown in the lower part of FIG. 2, the magneto-optical disk 100 has a buffer layer 2, an AlTi reflective layer 3, a SiN dielectric layer 4, a magneto-optical film 5, a SiN dielectric layer 6, It has a structure in which a hydrogen-containing carbon protective film 7 and a lubricant layer 8 are sequentially laminated. The substrate 1 was manufactured by mounting a stamper on which a concavo-convex pattern corresponding to the pre-pit data was formed in an injection molding die, and injecting a molten polycarbonate resin into the die. A track pitch of 0.5 μm and a groove width of 200
A guide groove having a width of 80 nm and a groove depth of 80 nm is formed in a spiral shape, and this guide groove is used as a track. The track is divided into a plurality of sectors. At the beginning of each sector, a prepit sector mark, VFO 11, and lower bit group 12 of track data are formed as prepit information as shown in FIG. Sector mark 14, upper bit group 15 of track data, sector number 16, C
It is composed of an RC code 17. Here, the address information, sector mark, VFO14,
Upper bit group 15 of track data, sector number 16,
The CRC code 17 reads the lower bit group 12 of the track data by the pre-pit in the initialization process of the disk,
The track position is checked and recorded. The disk surface in the area where address information was recorded by magneto-optical signals was flat. FIG. 4 shows a schematic diagram of the data. The hatched portions in the figure are concave patterns.

In this embodiment, the lower bit group 12 of the track data is 3 bits. For recording, gray code conversion was performed to reduce the influence of crosstalk between adjacent tracks. Gray code conversion is performed so that the number of different bits in the data sequence becomes 1 when the n-th data and the (n + 1) -th data are compared in a continuous data sequence, that is, the inter-code distance becomes 1. It is to convert each data. The gray code conversion of the track number may be performed as shown below, for example.

First, a desired track number is set to 2 bits of n bits.
Each bit is represented by tn, tn-1, tn-
2,... T2, t1, each bit gn, gn-1, gn-2,... Of the code after gray code conversion.
G2 and g1 are represented by the following equations.

Gm = tm + 1 ＾ tm (where m = tm + 1 ＾ tm)
1, 2,..., N−1, and ＾ indicates exclusive OR) gn = tn (n indicates the most significant bit) That is, the least significant bit t1 (first bit) of n bits And the exclusive OR of the next higher bit t2 (the second bit) is taken as the least significant bit g1 (the first bit) of the code after gray code conversion.
Next, the exclusive OR of the second bit t2 of the n bits and the third bit t3, which is one bit higher, is taken, and the obtained value is converted to the second bit g2 of the code after the gray code conversion.
And Similarly, the exclusive OR of the (n-1) th bit tn-1 of the n bits and the nth bit tn which is one order higher is taken, and the obtained value is converted to the code of the code after the gray code conversion. Let it be gn-1 of the (n-1) th bit. Then, the same bit as the most significant bit tn before the gray code conversion is added to the most significant bit gn of the code after the gray code conversion. When all the track numbers are sequentially converted in this way, the converted code obtained has an inter-code distance of 1. In this way, by performing the gray code conversion on the track number, the position where the bit is different from the track number of the adjacent track can be set at one position, that is, two positions on the tracks on both sides. Therefore, the number of locations where crosstalk occurs is reduced, and the track number can be reliably read.

Next, the pre-pit data 20 having such a configuration is described.
Using a sputtering apparatus (not shown), a buffer layer 2 made of a SiN dielectric and a reflective layer 3 made of AlTi were formed on both surfaces of a substrate 1 having a thickness of 20 nm and 80 nm, respectively. 4 with a film thickness of 2 nm and TbF
The magneto-optical film 5 made of eCo has a thickness of 20 nm, the SiN dielectric layer 6 has a thickness of 80 nm, and a hydrogen-containing carbon protective film 7.
Were sequentially formed with a film thickness of 10 nm. Next, a lubricant layer 8 made of Fomblin Z-DOL on the protective film 7
Was applied by a spin coater so that the film thickness became 2 nm. Thus, a magneto-optical disk 100 having the structure shown in FIG. 2 was manufactured.

Next, a magneto-optical disk 100 manufactured using a recording / reproducing apparatus having an optical system as shown in FIG.
Initialization and recording / reproduction are performed. The recording / reproducing apparatus includes a floating head on which the solid immersion lens 200 is mounted. A recording / reproducing apparatus having a floating head equipped with such a solid immersion lens is already known, and for example, JP-A-8-266369 can be referred to. In FIG. 5, a laser beam emitted from a laser light source 57 includes a lens 58, a prism 59a, and a prism 59a.
9b, passing through the beam splitter 60, mirrors 70 and 6
After being reflected at 9, the light enters the objective lens 71, is further condensed by the solid immersion lens 200, and focuses on the bottom surface of the solid immersion lens 200. Light oozing from the bottom surface of the solid immersion lens 200 reaches the recording layer of the magneto-optical recording medium 100 and forms a magnetic mark according to a recording signal. At the time of recording, a recording magnetic field is applied to the magneto-optical recording medium 100, and recording can be performed by any of the optical modulation method, the magnetic field modulation method, and the optical magnetic field modulation method. At the time of reproduction, the reflected light from the magneto-optical recording medium 100 is reflected by the mirrors 69 and 70, then reflected by the beam splitter 60, and split by the beam splitter 61 into light traveling toward the two beam splitters 64 and 65. The reflected light that has entered the beam splitter 65 is further split there and enters the focusing detection detector 68c and the tracking signal detection detector 68d, respectively. Also,
The reflected light that has passed through the half-wave plate 63 and the lens 67 and entered the beam splitter 64 enters photodetectors 68a and 68b that detect light of polarization components orthogonal to each other, and detects a reproduced signal. The signals from the prepits formed on the magneto-optical disk are detected by photodetectors 68a and 68b, and then output to the adder 81 of the detection circuit shown in FIG.
The adder 81 is connected to an AGC (Automatic Gain Control) amplifier 83 to stabilize the output amplitude, and the output signal is restored to a digital signal by a binarized signal processor 84. A sector pattern is detected from the data string of the restored digital signal. Further, a reproduction clock is generated from a digital signal based on the VFO pattern by a VCO (Voltage Controlled Oscillator) (not shown) of the pre-pit signal, and the lower bits of the generated reproduction clock and the track number of the digital signal can be restored.

In the initialization step, the lower bit group of the track number is confirmed, and the magneto-optical sector mark 14, the upper bit group 15 of the track data, the sector number 16, and the CRC code 17 are recorded. At this time, the track data recorded by the magneto-optical signal may be not only the upper bits but also all bits. Also, the track data is gray-coded in the same manner as the pre-pits, so that the influence of crosstalk can be reduced. In this embodiment, the track data is recorded as a 16-bit data sequence, and the sector data is recorded as a 4-bit data sequence. The CRC code represents information data composed of track data and sector data by a predetermined polynomial D (X), and generates this polynomial D (X) by a generation polynomial G (X) = X4 +
It is obtained as the remainder R divided by X + 1. To detect an error, the data including the remainder R (CRC code) and the polynomial D (X) is again divided by the generator polynomial G (X). At this time, if the remainder is 0, that is, if it is divisible, there is no error, and if the remainder is not 0, that is, if it is not divisible, there is an error. In normal recording and reproduction, a track number, a sector number, and a CRC code are restored from the data recorded in the pre-pit portion and the initialization step. With such a configuration, the correct answer rate of reading address data is dramatically improved, and the correct answer rate of about 80% when address information is formed only by prepits is 99.5% or more. Was. The accuracy rate was analyzed using a CRC code. (Embodiment 2) In this embodiment, a magneto-optical disk having the same configuration as that of Embodiment 1 was manufactured, and the configuration of the prepits was as shown in FIGS. In this configuration, CR recorded by a magneto-optical signal
By arranging the C code in an area sandwiched by the track grooves, crosstalk between tracks in CRC code reproduction is reduced. As a result, the correct reading rate of the address information was 99.7% or more.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments. For example, the information recording medium of the present invention is not limited to a magneto-optical disk, but may be a phase-change optical recording medium or a write-once optical recording medium having an organic dye in a recording layer, a read-only optical recording medium, or a land-groove recording medium. The present invention can be applied to any optical recording medium such as an optical recording medium. Further, the present invention is also applicable to a magnetic disk which records and reproduces magnetically.

[0022]

As described above, in an information recording disk in which a head slider on which a solid immersion lens is arranged and formed is levitated above the disk to perform recording and reproduction, reading accuracy from prepits is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pre-pit structure of a magneto-optical disk according to the present invention;

FIG. 2 is a configuration diagram of a disk used in the present invention.

FIG. 3 is a diagram for explaining a configuration of a track and a sector;

FIG. 4 is a schematic view of a magneto-optical disk prepit and a track groove according to the present invention.

FIG. 5 is a diagram schematically illustrating an optical system configuration of a recording / reproducing apparatus including a floating head equipped with a solid immersion lens.

FIG. 6 is a diagram schematically showing a configuration of a circuit for detecting a pre-pit signal of the recording / reproducing apparatus.

FIG. 7 is a diagram showing the structure of a magneto-optical disk prepit according to the present invention.

FIG. 8 is a schematic view of a magneto-optical disk prepit and a track groove according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disk substrate 2 Buffer layer 3 Reflection film Au 4 Dielectric SiN 5 Magneto-optical film TbFeCo 6 Dielectric SiN 7 Protective film CH 8 Lubricating film 11 VFO 12 Lower bit group of track data 13 Gap portion 14 Magneto-optical sector mark 15 Track Upper bits of data 16 Sector number 17 CRC code 100 Magneto-optical disk

Claims (5)

[Claims] 1. An information recording / reproducing apparatus for reading address information by reproducing a reproduction signal of a pre-pit formed in advance on a medium and information recorded in advance. 2. The information recording apparatus according to claim 1, wherein
The address information indicates that a prepit or data is formed or recorded in a time series according to a sector mark, an address read timing adjustment VFO pattern, a track number, a sector number, and CRC data for checking whether reading is accurate. Characteristic information recording device. 3. The information recording / reproducing apparatus according to claim 1, wherein the recording / reproducing is performed by floating a head slider on which a solid immersion lens is disposed on a disk. 4. The information recording apparatus according to claim 1, wherein
An information recording apparatus, wherein pre-pits formed in advance on a medium correspond to lower bits of a track number. 5. An information recording medium, wherein prepits corresponding to a part of address information are previously formed on a medium, and an area for recording a part of the address information is provided.