JPH0944854A - Optical disk and recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to confine the amplitude of reproduced signals within nearly a specified range and to surely binarize the reproduced signals even in higher-density recording by making both sides in the longitudinal directions of the densest pit strings long. SOLUTION: Both sides in the longitudinal direction of prepits are made long without changing the positions of the prepits of the densest pit strings of the optical disk and the duty ratio 50%% of the prepits of the densest bit strings and the blank parts therebetween is so set as to be shorter in the blank parts and to attain 0.3/0.7%. The blank parts of the other pit strings are set at the length of the blank of the densest pit strings. Thereby, irregularity does not occur at intervals of 1, 0 after the binarization at the time of production as shown by (d) and (e) in the fig. In addition, the differences in the levels of the amplitudes of the reproduced signals between the densest patterns and the coarsest patterns are decreased and, therefore, such inconvenience that the reading of header parts is no longer possible, is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc and a method for manufacturing the optical disc, and more particularly to an optical disc capable of high density recording and a recording method for forming and recording a preformat on the optical disc.

[0002]

2. Description of the Related Art In recent years, with the increase in capacity of information, an optical disk has been attracting attention as a memory for storing the information. Since an optical disk has recording marks of substantially the same size formed on a recording film by a laser beam focused on a beam spot having a diameter of about 1 μm, extremely high density recording is possible.

An optical disk is a rewritable type typified by a CD or an LD, a write-once type typified by an electronic filing device that can be written only once, and rewritable like an HDD or an FDD. It is roughly divided into rewritable type. Further, in a rewritable type optical disk, a magneto-optical recording method in which a magnetic field is applied to a perpendicularly magnetized film and a laser beam is irradiated to record / erase information, and the recording film is made amorphous and crystalline by laser beam irradiation. There is a phase change recording method in which information is recorded / erased by being selectively changed to and.

With the recent increase in the density of these optical disks, the density of the embossed pit information written on the optical disk in advance has also been increased. As the pit mark string, for example, the preamble portion as shown in FIGS. 8A and 8B is a close-packed pattern of embossed pits P1, followed by other relatively sparse pits P2 such as a header. When the patterns of FIG. 8 are arranged, the light beam spot Bs normally has two pits P1 as shown in FIG. 8B if the closest pattern is sufficiently spaced from the light beam spot. , P2 are not simultaneously irradiated, and the signal amplitude of the densest pattern and the signal amplitude of the sparsest pattern do not change much as shown in (c) of FIG. As shown by the broken line, the binarized threshold level Th can be made substantially constant. In order to increase the recording density of information with respect to such an array, if the interval between the embossed pits P1 of the close-packed pattern is narrowed as shown in FIGS. ), The light beam spot Bs is simultaneously formed in the two closest pits, and the upper end of the reproduction signal becomes lower and the lower end becomes higher as shown in FIG. 9C. As a result, the signal amplitude of the close-packed pattern becomes smaller.

When the slice level is set for the binarization of the reproduced signal waveform shown in FIGS. 8C and 9C, the closest packing as shown in FIG. When the signal amplitude of the pattern and the signal amplitude of the relatively sparse pattern are substantially the same, the slice level Th is substantially constant as described above, and does not change so much at the transition of the pattern.
On the other hand, as shown in FIG. 9C, when the signal amplitudes of the close-packed pattern and the signal amplitudes of other patterns are significantly different, the slice levels Th1 and Th2 that are constantly set at the approximate centers of the amplitudes. However, there is a problem that the pit string in the header part becomes unreadable because the signal amplitude cannot keep up with the change.

In order to solve this problem, the following proposals have been made. That is, FIG. 10 shows an example in which the prepit pattern is improved. In this example, in a close-packed pattern in which short pit rows are densely arranged, a pattern corresponding to 1 and 0 is formed with a duty ratio of 50%, and a concave portion where a signal is dark, that is, a pit is a convex portion, That is, the duty ratio is set to, for example, 60% to 70% so as to be longer than the blank as the flat portion between pits. Further, the concave portion that becomes darker is set longer than the normal setting even for a sparse pattern in which a relatively long pit row is arranged such as the ID portion, and the convex portion is set to be the same as the close-packed pattern. .

As described above, the effect of suppressing the fluctuation of the threshold level for binarization will be described even if the duty ratio of the concave portion is increased and the convex portion is shortened to increase the density.

First, the light beam spots a1 and a whose centers are substantially formed in the flat portion between the pits shown in FIG. 9B showing the pit arrangement in the conventional optical disk.
Focusing on No. 2, when the pre-pits of the close-packed pattern are formed with a duty ratio of 50%, the bright parts in the light beam spots a1 and a2 are the convex part in the close-packed pattern part and the convex part in the sparsest pattern part. The ratio of dark areas is exactly the same. Further, focusing on the concave portions of the densest pattern and the sparsest pattern, that is, the light beam spots b1 and b2 whose centers are substantially located in the pits, the spots corresponding to the densest pattern portions are the sparsest pattern portions. It can be seen that there are more bright areas than in the spot hit. As a result, the intensity of light returning from the convex portions of the densest pattern and the sparsest pattern is substantially the same, and the intensity of light returning from the concave portions is darker in the sparse pattern. . Therefore, the reproduced signal can be obtained as shown in FIG.

Next, the improved pit train is shown in FIG.
This will be described with reference to FIG. As shown in (b) of FIG. 10, in the light beam spots c1 and c2 which hit the convex portions of the densest pattern and the sparsest pattern, the ratio of the bright portion and the dark portion is the same, but (b) of FIG. 10), the bright part is narrower than that of the spots a1 and a2 shown in FIG.
As shown in FIG. 9, the light intensity returned from the bright portion is darker than in the case of FIG. 9C. On the other hand, FIG.
As shown in (b) of 0, the ratio of the bright part and the dark part in the light beam spots d1 and d2 formed in the recesses of the densest pattern and the sparsest pattern is larger in the dark part of the sparser pattern. Comparing the light beam spot b1 shown in (b) of 10 and the light beam spot d1 shown in (b) of FIG. 10, it can be seen that the ratio of the dark portion is larger in the light beam spot d1.

The above is the absolute value of the signal level of the reproduction signal (signal level A1 in FIG. 9C and FIG. 10C).
, A2, B1, B2, C1, C2, D1, D2. ), A1 = A2> C1 = C2, B1> B2, D1> D2 and B1> D1, B2 = D2, and comparing the amplitudes of the reproduced signals, A1-B1 <C1-D1, A2 -B2> C2-D2, and as is clear from the comparison between FIGS. 9 and 10, the reproduction signal amplitude from the densest pattern is larger and the reproduction signal amplitude from the sparsest pattern is smaller. .
As a result, the relative change amount of the reproduced signal amplitude from the densest pattern and the sparsest pattern is small.

However, this improved proposal also has the following drawbacks. As shown in (a) to (c) of FIG. 11, in the case of the conventional example, the reproduced waveforms of the densest pattern and the sparsest pattern have large amplitude fluctuations. The patterns are basically arranged at equal intervals. However, as shown in (d) to (e) of FIG. 11, the duty of the dark portion is unidirectionally applied from one end (the wavy line portion in the figure) of the concave portion which should originally be dark. As the reproduction waveform is increased, some of the reproduced waveform has large jitter. When this is binarized, (f) in FIG.
As you can see from the sequence of 1 and 0 in (g), g1 and g
Irregularities such as 2, g3, and g4 occurred, which caused an error.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when reproducing prepits having an increased recording density, the densest pattern is followed by the sparsest pattern. A prepit pattern is formed in advance so as to minimize a slice level variation when binarizing, or a slice level variation when binarizing a densest pattern subsequently to a sparsest pattern, and a reproduction signal It is an object of the present invention to provide an optical disc and a method for manufacturing the same that can suppress the occurrence of errors without increasing the jitter.

[0013]

The optical disc of the present invention has a synchronization data composed of a plurality of pits arranged in a dense pattern on each of a plurality of tracks, and a closest packing pit row composed of a plurality of blanks between the pits. A beam formed on a pit row by a focused beam focused on the sparse pit row consisting of a plurality of pits arranged in a sparse pattern and a plurality of blanks between the pits The spot spreads to the end of one blank and two pits continuous to it in the closest pit row, or one pit of the closest pit row fits into the light spot. In the case where multiple pre-format data in which is set are recorded, the pre-format data Set the duty ratio of the pits in the closest pit row and the blank part between them so that the blank part is shorter than the other, by increasing both sides in the length direction of the pit without changing the original position of the pit. The blank portions of the other pit rows are set to the blank length of the closest pit row.

The optical disk of the present invention is arranged in a sparse pattern with synchronization data composed of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits. Address data consisting of sparse pit rows consisting of multiple pits and multiple blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is the closest pit row. A plurality of pits and blanks are set in such a way that one blank and two pits continuous with the blank extend to both ends, or one pit in the closest packed pit row enters the light spot. Preformatted data of is recorded, data is recorded following the preformatted data, and this recorded data is Of the preformatted data, the pits in the closest packed pit row and the blanks between them are made longer by lengthening both sides of the pits in the closest packed pit row without changing the original position of the pits. The duty ratio of is set so that the blank portion becomes shorter, and the blank portions of the other pit rows are set to the blank length of the closest pit row.

The optical disc of the present invention is arranged in a sparse pattern with synchronization data composed of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packed pit row consisting of a plurality of blanks between the pits. Address data consisting of sparse pit rows consisting of multiple pits and multiple blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is the closest pit row. A plurality of pits and blanks are set in such a way that one blank and two pits continuous with the blank extend to both ends, or one pit in the closest packed pit row enters the light spot. Preformatted data is recorded, and the recorded data is reproduced after the preformatted data. The duty ratio of the pits of the closest pit row and the blank portion between them is set to the blank portion by lengthening both sides in the length direction of the pits of the preformatted data without changing the original position of the pits of the closest pit row. Is set to be shorter, and the blank portions of the other pit rows are set to the blank length of the closest pit row.

The optical disk of the present invention is arranged in a sparse pattern with synchronization data composed of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits. Address data consisting of sparse pit rows consisting of multiple pits and multiple blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is the closest pit row. A plurality of pits and blanks are set in such a way that one blank and two pits continuous with the blank extend to both ends, or one pit in the closest packed pit row enters the light spot. Preformatted data is recorded, and data is recorded following the preformatted data, the preformer In the data, the duty ratio of the pits in the closest pit row and the blank portion between them is set to be greater than that of the pits in the closest pit row by extending both sides in the longitudinal direction of the pit row without changing the original position of the pits in the closest pit row. Is set to be short, and the blank part of other pit rows is
It is set to the blank length of the closest pit row.

The optical disk of the present invention is arranged in a sparse pattern with synchronization data consisting of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits. Address data consisting of sparse pit rows consisting of multiple pits and multiple blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is the closest pit row. A plurality of pits and blanks are set in such a way that one blank and two pits continuous with the blank extend to both ends, or one pit in the closest packed pit row enters the light spot. Of the preformatted data of the preformatted data, the pits in the closest packed pit row originally exist. By setting both sides in the length direction of the pits to be long without changing the position, the duty ratio of the pits in the closest pit row and the blank area between them is set to be shorter in the blank area, and The blank part of is set to the blank length of the closest pit row.

The recording apparatus of the present invention records preformatted data composed of a reference synchronization code at the time of reproduction and address data indicating a position on the optical disc at predetermined intervals on a track on the optical disc. Converting means for converting the address data corresponding to the upper position into a code, generating means for generating a light beam according to the synchronization code and the code converted by this converting means, and an optical disk by the light beam generated by this generating means A plurality of pits arranged in a dense pattern corresponding to the sync code above and a closest pit row consisting of a plurality of blanks between pits, and a plurality of pits arranged in a sparse pattern corresponding to the address data code Pre-formatted data consisting of sparse pit rows consisting of multiple blanks in between The close-packed pit string is provided with a recording unit and by making both sides of the pre-format data recorded by this recording unit in the longitudinal direction of the close-packed pit string longer without changing the original position of the pit. The duty ratios of the pits and the blank portion between them are set so that the blank portion becomes shorter, and the blank portions of the other pit rows are set to the blank length of the closest pit row.

In the recording method of the present invention, preformatted data consisting of a reference synchronization code at the time of reproduction and address data indicating a position on the optical disk is recorded on a track on the optical disk at predetermined intervals. The address data corresponding to the upper position is converted into a code, a light beam is generated according to the sync code and the converted code, and the generated light beam causes a dense pattern corresponding to the sync code on the optical disc. Closed pit string consisting of multiple pits arranged in a row and multiple blanks between pits, and sparse pit string consisting of multiple pits arranged in a sparse pattern corresponding to the address data code and multiple blanks between pits The pre-formatted data consisting of The lengths of both sides in the longitudinal direction of the pits are made longer without changing the original position of the pits so that the duty ratio of the pits in the closest pit row and the blank part between them becomes shorter in the blank part. Set the blank portion of the other pit row to the length of the blank of the closest pit row.

The master disc manufacturing apparatus of the present invention is a pre-format composed of a reference synchronization code at the time of reproduction with respect to a track on the master disc used for producing an optical disc and address data indicating a position on the optical disc. In data recording, a conversion means for converting address data corresponding to a position on the master into a code, a generation means for generating a light beam according to the synchronization code and the code converted by the conversion means, and this generation means The densified pattern corresponding to the code of the address data and the closest pit row consisting of multiple pits arranged in a dense pattern corresponding to the synchronization code on the master and multiple blanks between the pits by the light beam generated by A preformer consisting of sparse pit rows consisting of multiple pits arranged and multiple blanks between the pits. It has a generating means for generating data,
The preformat data created by this creating means lengthens both sides in the length direction of the closest packed pit row without changing the original position of the pits in the closest packed pit row, and thus the pits in the closest packed pit row and the blanks between them. The duty ratio of the portion is set to be shorter in the blank portion, and the blank portions of the other pit rows are set to the blank length of the closest pit row.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An optical disc according to an embodiment of the present invention and a method of recording and forming preformatted data on the optical disc will be described below with reference to the drawings. FIGS. 1A to 1C and FIGS. 2A to 2E show an example of a pattern of a preformatted pit row P formed by the preformat recording method for the optical disc 1 of the present invention. An example of the reproduction signal is shown.

In general, it is formatted, eg, M
In the CAV-formatted optical disc, the tracks are arranged in a substantially concentric pattern, and are divided into a plurality of belt-shaped regions, that is, a plurality of zones in the radial direction, that is, a plurality of zones, and data are arranged along the circumferential direction. Is divided into multiple sectors as a unit for recording
The number of sectors is set to be the same. For each zone, a data clock having a unique specific frequency for reproducing data from a track belonging to that zone and for recording data is defined and recorded in advance in the header part of the track. There is. Each sector of each zone of the optical disk is composed of a header portion as a preformatted area which is recorded in advance as format information and a data field as a data area in which the user later records information. In the header section, a sector mark section that clearly indicates the start of one sector, a VFO section in which a synchronization code for deriving a data clock is recorded, and a plurality of ID sections in which ID information is recorded are arranged periodically. In addition, at the end of the data field, a gap area in which no data is written is provided to clarify the boundary between the next sector and the data field.
The VFO section, the ID information section, and the data field are (2-
7) Modulated data, "0" between "1" and "1"
A pit mark is formed on the optical disc 1 by the modulated data in the form of 2 to 7 inserted and reproduced. I
A track number, a sector number, and a CRC code are recorded as ID information in the D section. In the VFO section,
A synchronization code such as "101010 ..." In which "1" is read at a constant cycle is recorded. These signals are
It is supplied to the data processing circuit as a reproduction signal, and in this data processing circuit, ID information as pre-formatted data, that is, address information (track number, sector number, etc.) and reproduction data are read by a data clock unique to each zone. .

In the close-packed pattern in which short pit rows are densely arranged like the VFO portion of the present invention, a pattern corresponding to 1 and 0 is formed at a duty ratio of 50%, and a concave portion where a signal becomes dark That is, the duty ratio is set to, for example, 60% to 70% so that the pit becomes longer than the blank as the convex portion, that is, the flat portion between the pits. At this time, the length of the pits is increased by lengthening both sides of the pre-pits in the lengthwise direction of the pre-pits in the densest pit row without changing their original positions. Also,
Even for a sparse pattern in which relatively long pit rows are arranged, such as an ID part, the darkened concave portion is set longer than the normal setting, and the convex portion is set to be the same as the close-packed pattern.

As described above, as shown in FIGS. 1A and 1B and FIGS. 2A and 2B, the center position of the embossed pit to be produced with the conventional duty of 50% is not changed. It is characterized in that a concave portion corresponding to a dark portion is extended to both sides with respect to the center of the pit. By doing this, (c) of FIG.
As shown in (c) of FIG. 2, the center positions of the bright and dark parts do not change. Therefore, as shown in (d) and (e) of FIG. Since the regularity does not occur and the amplitude difference between the reproduction signals of the densest pattern and the sparsest pattern is reduced, the problem that the header part becomes unreadable is also eliminated.

The method for manufacturing the optical disk of the present invention will be described below with reference to examples. (Embodiment 1) A process of manufacturing an optical disk master used for manufacturing the optical disk of the present invention will be described with reference to FIGS. First, the glass substrate 5 is washed as shown in FIG.
Then, this glass substrate 5 is dried. Next, as shown in FIG. 3B, a photoresist 6 is applied to this glass substrate 5. The glass original plate 5 coated with the photoresist 6 is referred to as an optical disc master. As shown in FIG. 3C, a laser beam 7 modulated according to the format information is focused on the photoresist 6 by the objective lens 8 and the photoresist 6 is exposed. As a result, the photosensitive portion 9 is formed on the photoresist 6. Then, the photosensitive portion 9 is removed by developing the optical disk master shown in FIG. 3C, and pits 10 are formed as shown in FIG. 3D.

The cross-sectional shape of the pit 10 is usually rectangular or trapezoidal. The reproduction signal has the maximum film thickness d of the conventional optical disk master. λ / 4n (λ: reproducing laser wavelength, n: refractive index of the substrate), and the film thickness d and the pit depth d are set to be the same.

Under this background, the following simulation was performed using the master disk manufacturing apparatus. As shown by reference characters b1 and d1 in FIGS. 9 and 10, in order to simulate high density recording, it is assumed that the minimum pit corresponding to the close-packed pattern completely fits into the beam spot of the reproducing laser beam. First, in order to set the duty ratio of 50% in the conventional example with or without pits, the photoresist 6 was exposed to light by turning on and off the pulse width of the laser light 7 at a duty ratio of 50%. The length of the pit actually formed on the substrate is uniquely determined by the rotation speed of the photoresist-coated substrate and the on / off time of the laser beam. In the case of this example, since the reproduction light beam has a wavelength of 685 nm and an NA of the objective lens of 0.6, the diameter of the laser spot focused on the substrate is about 1 μm. Therefore, in this example, a master was prepared so that the pit length of the concave portions was 0.5 μm and the convex portion length without pits was 0.5 μm. The length of the recess without pits is 0.5 μm even when the long pits other than the close-packed pattern are continued. This master is sample A
I named it.

Next, in order to confirm the effect of the present invention that the amplitude fluctuation of the reproduction signal in the optical disc in which the duty ratio of the closest pit pattern is changed as shown in FIG. Correspondingly, the duty ratio of the irradiation laser pulse on and off was changed to 60% and 40%, 70% and 30%, 80% and 20%, and irradiation was performed on the photoresist to correspond to the closest pattern on the disk. Actual physical pit (recess) and blank (convex)
Are 0.6 μm and 0.4 μm, 0.7 μm and 0.
The masters having the sizes of 3 μm, 0.8 μm and 0.2 μm were prepared, and these were designated as sample B, sample C and sample D, respectively. The irradiation laser pulse is turned on /
When turned off, cutting was performed so as to extend the recesses on both sides without changing the original center position of the physical pits (recesses). In Samples B, C, and D, the lengths of blanks (projections) following long pits other than the close-packed pattern were 0.
It goes without saying that the sizes are 4 μm, 0.3 μm, and 0.2 μm, and the center position of the convex portion is not displaced from the original position. These relationships are shown in (a), (b) of FIG.
(C) and (d) show.

By using the thus prepared 3.5-inch disk masters of Samples A, B, C, and D, plating was performed to manufacture a stamper. These stampers A,
Further, plastic substrates were molded using B, C, and D, and disc substrates A, B, C, and D made of polycarbonate and having a diameter of 3.5 inches and a thickness of 1.2 mm were manufactured.
Further, these disk substrates were set in a vacuum vapor deposition device, and a reflective film made of Al was formed. The finally prepared disc samples for reproduction were named Samples A, B, C and D corresponding to the first master discs.

These 3.5 inch diameter sample disks A, B, C and D were loaded into the disk drive device shown in FIG. 5 and binarization experiments of reproduced signals were conducted. The disk 21 shown in FIG. 5 was rotated by the spindle motor 22 to a predetermined rotation speed. The disk 21 has a pit-shaped group groove formed by the previous master recording, and the optical head 20 moves so as to follow the surface deviation of the group groove and the disk, and the focus drive control 31 and the track drive control 32. It is controlled by each circuit. The prepits on the disk surface 29 are read by the laser beam controlled by the laser driver circuit 27 and reproduced by the optical head 20, and the reproduced analog signal is amplified by the preamplifier 23 and by the binarization circuit 24. It is converted into a binary signal of 1 and 0, passes through the modulation / demodulation circuit 25, and is reproduced as the original information 26 recorded on the master.

The binarizing circuit 24 refers to a certain slice level for binarizing the analog signal, detects a peak of a waveform higher than that level, and outputs a logical value 1 as the detection output. . Further, a waveform lower than that level is detected and a logical value 0 is output. Such a slice level is generally set at the center of the waveform amplitude.

These sample disks A, B, C, D
Since the computer data is input as information, first, the slice level of the binarization circuit is pulled in by the PLL. Therefore, the closest part of the pre-pit pattern called the preamble and the header part indicating the address of the following data. , And then the data part.

In this embodiment, it was tested whether the header portion following the preamble could be read by the binarization circuit of this drive. As a result, in the sample A and B discs, the slice level varied greatly in the header portion following the preamble portion, and the header could not be read. On the other hand, in the samples C and D, the header could be read normally. (A), (b),
(C) and (d) show reproduced analog waveforms of the sample disks A and C produced in this example. In (c) and (d) of FIG. 6, the step difference between the preamble signal and the header signal amplitude is large, whereas in (a) of FIG.
In (b), it can be easily understood that the change is largely gradual.

Next, when the read rates of the headers of Samples C and D of these were measured, they were over 99.999% for the inner, middle and outer rims of the disc, respectively, and it was confirmed that no error occurred on both discs. confirmed.

As described above, according to the present invention, information is reproduced by irradiating an information recording medium such as an optical disk with continuous light, and the uneven pre-pits formed on the substrate and the pre-pits on the substrate are reproduced. The relationship of the diameter of the condensed light spot (the diameter of the part where the central intensity of light becomes 1 / e2) is (1) at least the light spot diameter is applied to both ends of two pre-pits corresponding to the close-packed pattern. In case (2), one pre-pit corresponding to the close-packed pattern almost enters the light spot, both sides of the pre-pit should be changed without changing the position where the original pre-pit should be. By stretching, the duty ratio is set so that the blank part becomes shorter without changing the center position of the pre-pit part corresponding to the densest pattern and the blank part between them. By setting the blank part for other sparse patterns to be the same as the length of the blank corresponding to the close-packed pattern, the fluctuation of the jitter of the reproduced waveform during reproduction is reduced, and as a result, the occurrence of errors is suppressed, and yet , It is possible to stabilize the slice level of the signal processing by reducing the fluctuation of the reproduction signal amplitude between the densest pattern and the other particularly sparsest pattern, and perform stable binarization.

The present invention, in both the conventional example and the embodiment,
Although the pre-pit portion is a concave portion and the blank portion is a convex portion, it is needless to say that the same effect can be expected even when the pre-pit portion is convex and the blank portion is concave. Further, although the present invention has been described with respect to the case where the pre-pits are formed in advance on the substrate, the recording film is formed on the substrate, and the laser light of the drive device is focused on the recording film to make the write-once type. It is needless to say that the same effect can be expected even in the case of recording or erasable recording. Examples of the phase change type recordable / erasable optical disc will be described below.

(Example 2) As shown in FIG. 7, ZnS.SiO 2 was formed on a polycarbonate substrate having a diameter of 3.5 inches and a thickness of 1.2 mm in which continuous group grooves were formed.
The dielectric film 51 made of 2700A, GeSbTe 3
The phase-change recording film 52 made of the original alloy is 200 A, ZnS
Recording / reproduction was performed using the optical disk drive device shown in FIG. 5 with respect to the phase change type optical disk in which the SiO2 dielectric film 53 was 200 A and the reflection film 54 made of Al alloy was 2000 A, which were laminated in this order.

The pulse pattern generator 34 passes the generated close-packed pattern and arbitrary waveform pattern in this order through the A / D converter 35, and then the optical head 20 is driven by the laser drive circuit 27 to drive the laser on the optical disk surface. Marks corresponding to the close-packed pattern and the arbitrary pattern were recorded on the phase change optical disk 21 with a recording power of 13 mW. In this case, the laser wavelength is 685 nm and the objective lens NA is 0.6.
Therefore, the diameter of the focused laser is about 1 μm. The phase change optical disk 21 has a reflectance of about 2 in the unrecorded area.
When recording is performed at 0%, the reflectance of the mark portion is reduced to 10%.

The minimum mark diameter recorded is about 0.5 μm.
When the shortest pit pitch is about 1.0 μm in m,
The same experiment was performed as in the case of the prepits of FIGS. 6A, 6B, 6C, and 6D. That is, by controlling the pulse width of the recording laser, the length of a dark recording mark having a reflectance of 10% is set to 0 by extending it to both sides of the mark without changing the center position of the mark to be originally recorded. .5μ
m, 0.6 μm, 0.7 μm, 0.8 μm, corresponding to this, a bright blank part with a reflectance of 20% is 0.5 μm.
The closest-packed pattern was recorded so that m, 0.4 μm, 0.3 μm, and 0.2 μm. Further, after each close-packed pattern, the recording mark has an arbitrary length, and the blank portions have 0.5 μm, 0.4 μm, 0.3 μm, and
Data was recorded according to the pit position recording by (2, 7) modulation so as to be 0.2 μm. These recorded data are treated in the same manner as shown in FIG. 4, and data A, B, C, D
And Then, the laser power was lowered to 0.7 mW and reproduction was performed with continuous light. In the binarization method, the center of the reproduced waveform was sliced as in the first embodiment. In the second embodiment, unlike the first embodiment, the dark portion (center position of the mark) of the reproduction light amount becomes 1 and the bright portion (center of the blank portion) becomes 0. Similar to the first embodiment, the PLL is pulled in with the preamble corresponding to the close-packed pattern, and when the subsequent data portion is binarized, the data A cannot be discriminated, but the data B, C,
D was able to reproduce the information when it was recorded.

As described above, according to the present invention, information is recorded / erased / reproduced by irradiating a recording medium such as an optical disk with a laser beam, and the shortest recording mark corresponding to the closest pattern is condensed. The relationship between the light spot diameters (the diameter of the portion where the central intensity of light becomes 1 / e2) is (1) when at least the light spot diameters are applied to both ends of two recording marks corresponding to the close-packed pattern, or ( 2) In the case where one of the shortest recording marks corresponding to the close-packed pattern almost enters the light spot, the length of the marks should be changed without changing the center position where the recording marks should be originally formed. By extending to both sides, the shortest recording mark corresponding to the densest pattern and the duty ratio of the blank part between them are recorded so that the blank part becomes shorter, and it is recorded to other sparse patterns. The rank portion is recorded in the same length as the blank corresponding to the close-packed pattern so that the center position of the mark portion and the center position of the blank portion are not changed during the reproduction binarization signal processing. It is possible to stabilize the slice level of the signal processing and to perform stable binarization without increasing the jitter of, and by suppressing the amplitude variation between the densest pattern and other patterns, especially the sparsest pattern. .

[0041]

As described above, according to the recording method of the present invention, the amplitude of the reproduction signal can be kept within a substantially constant range, and the reproduction signal can be surely binarized even in the high density recording. An optical disc can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a pit array arranged at high density of an optical disc of the present invention, a plan view showing a relationship between a focused spot diameter and a pre-pit array of this high density array, and a waveform of a reproduced signal reproduced. It is a figure.

FIG. 2 is a diagram showing a position of an embossed pit of the present invention with respect to an embossed pit to be produced with a conventional duty of 50%, a reproduction signal by the embossed pit, and a binarized output.

3 is a cross-sectional view schematically showing a process of manufacturing a master for manufacturing the optical disc shown in FIGS. 1 and 2. FIG.

4A to 4C are plan views showing various examples of pit rows of a sample optical disk made from various masters manufactured by the process shown in FIG.

FIG. 5 is a block diagram schematically showing an optical disc device for reproducing the sample optical disc shown in FIG.

6 is a waveform diagram showing a reproduction signal reproduced from the sample disc shown in FIG.

FIG. 7 is a sectional view of an optical disc to which the recording method of the present invention is applied.

FIG. 8 is a cross-sectional view showing a pit train of a conventional optical disc, a plan view showing a relationship between a focused spot diameter and a pre-pit train, and a waveform diagram of a reproduced signal reproduced.

FIG. 9 is a cross-sectional view showing a pit array arranged in high density of a conventional optical disc, a plan view showing a relationship between a focused spot diameter and pre-pit arrays in this high density array, and a waveform diagram of a reproduced signal reproduced. Is.

10 is a cross-sectional view showing a pit array arranged at high density of an optical disc for the example in which the problem of FIG. 9 is improved, a plan view showing a relationship between a focused spot diameter and a pre-pit array of this high density array, FIG. 6 is a waveform diagram of a reproduced signal that is reproduced.

FIG. 11 illustrates a reproduction signal and a binarized output by an embossed pit to be produced with a duty of 50% and a reproduction signal and a binarized output by an improved embossed pit for explaining the problem in the improved example of FIG. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk P ... Pre-format pit row 5 ... Glass substrate 6 ... Photoresist 8 ... Objective lens 9 ... Photosensitive part 20 ... Optical head

Claims (8)

[Claims] 1. Synchronous data consisting of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits, and a plurality of pits arranged in a sparse pattern. And address data consisting of a sparse pit row consisting of a plurality of blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is one blank in the closest pit row. And spread to both ends of two consecutive pits, or 1 of the closest pit row
In an optical disc that records multiple preformat data in which pits and blanks are set in relation to the size of one pit entering the light spot, the pits in the closest pit row of the preformat data should be the original pits. By increasing both sides in the length direction of the pit without changing the position, the duty ratio of the pits in the closest pit row and the blank area between them is set to be shorter in the blank area, and An optical disc characterized in that the blank portion is set to the blank length of the closest pit row. 2. Synchronous data consisting of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits, and a plurality of pits arranged in a sparse pattern. And address data consisting of a sparse pit row consisting of a plurality of blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is one blank in the closest pit row. And spread to both ends of two consecutive pits, or 1 of the closest pit row
Plural preformat data in which pits and blanks are set in relation to the size of one pit entering the light spot, data is recorded following the preformat data, and this recorded data is reproduced. In an optical disc to be used, by lengthening both sides of the pre-format data in the longitudinal direction of the pits in the closest packed pit row without changing the original position of the pits in the closest packed pit row, An optical disc characterized in that the duty ratio is set to be shorter in the blank portion, and the blank portions in the other pit rows are set to the blank length of the closest pit row. 3. Synchronous data consisting of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits, and a plurality of pits arranged in a sparse pattern. And address data consisting of a sparse pit row consisting of a plurality of blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is one blank in the closest pit row. And spread to both ends of two consecutive pits, or 1 of the closest pit row
In an optical disc in which multiple preformat data in which pits and blanks are set in relation to the size of one pit entering the light spot and the data recorded after the preformat data is reproduced, By increasing both sides in the length direction of the pits in the format data without changing the original positions of the pits in the closest pit row, the duty ratio of the pits in the closest pit row and the blank area between The optical disc is characterized in that the shorter one is set, and the blank portions of the other pit rows are set to the blank length of the closest pit row. 4. Synchronous data composed of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packing pit row consisting of a plurality of blanks between the pits, and a plurality of pits arranged in a sparse pattern. And address data consisting of a sparse pit row consisting of a plurality of blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is one blank in the closest pit row. And spread to both ends of two consecutive pits, or 1 of the closest pit row
In an optical disc in which multiple preformat data in which pits and blanks are set in relation to the size of one pit entering the light spot and data is recorded following the preformat data, By increasing both sides of the pits in the closest pit row in the length direction without changing the original position of the pits, the duty ratio of the pits in the closest pit row and the blank portion between them becomes shorter in the blank portion. The optical disc is characterized in that the blank portions of the other pit rows are set to the blank length of the closest pit row. 5. Synchronous data composed of a plurality of pits arranged in a dense pattern on each of a plurality of tracks and a closest packed pit row consisting of a plurality of blanks between the pits, and a plurality of pits arranged in a sparse pattern. And address data consisting of a sparse pit row consisting of a plurality of blanks between pits, and the beam spot formed on the pit row by the focused beam focused on this pit row is one blank in the closest pit row. And spread to both ends of two consecutive pits, or 1 of the closest pit row
In an optical disc that records multiple preformat data in which pits and blanks are set in relation to the size of one pit entering the light spot, the pits in the closest pit row of the preformat data should be the original pits. By increasing both sides in the length direction of the pit without changing the position, the duty ratio of the pits in the closest pit row and the blank area between them is set to be shorter in the blank area, and The blank portion is set to the blank length of the closest pit row, which is a recording method. 6. A recording device for recording pre-format data, which comprises a reference synchronization code at the time of reproduction and address data indicating a position on the optical disc at predetermined intervals with respect to a track on the optical disc, at a position on the optical disc. A conversion means for converting the corresponding address data into a code, a generation means for generating a light beam in accordance with the synchronization code and the code converted by this conversion means, and a light beam generated by this generation means on the optical disk. Between a plurality of pits arranged in a dense pattern corresponding to the synchronization code and between the pits, and between a plurality of pits arranged in a sparse pattern corresponding to the code of the address data and the closest packing pit row and between the pits Recording means for recording pre-formatted data consisting of a row of sparse pits consisting of a plurality of blanks The preformatted data recorded by this recording means has the pits in the closest packed pit row that are lengthened on both sides in the longitudinal direction of the closest packed pit row without changing the original positions of the pits in the closest packed pit row. The recording is characterized in that the duty ratio of the blank portion between them and the blank portion are set so that the blank portion becomes shorter, and the blank portions of the other pit rows are set to the blank length of the closest pit row. apparatus. 7. A recording method for recording pre-formatted data consisting of a reference synchronization code at the time of reproduction on a track on an optical disc and address data indicating a position on the optical disc, at a position on the optical disc. The corresponding address data is converted into a code, and a light beam is generated according to the sync code and the converted code, and the generated light beam arranges a dense pattern corresponding to the sync code on the optical disc. Pre-format consisting of multiple pits and a close-packed pit sequence consisting of multiple blanks between pits, multiple pits arranged in a sparse pattern corresponding to the address data code, and a sparse pit sequence consisting of multiple blanks between pits Data is recorded, and the pits in the closest pit row of this recorded preformat data By setting both sides in the length direction of the pits without changing the position that should be originally, the duty ratio of the pits of the closest pit row and the blank part between them is set to be shorter in the blank part, and other A recording method characterized in that the blank portion of the pit row is set to the blank length of the closest pit row. 8. A master disc manufacturing method for recording pre-formatted data, which is composed of a reference synchronization code at the time of reproduction and address data indicating a position on the optical disc, at predetermined intervals with respect to a track on the master disc used for producing an optical disc. In the apparatus, conversion means for converting the address data corresponding to the position on the master to a code, generating means for generating a light beam according to the synchronization code and the code converted by this conversion means, and the generation means The pits are arranged in a dense pattern corresponding to the sync code on the master by the optical beam and are arranged in a sparse pattern corresponding to the code of the address data and the closest packed pit row consisting of a plurality of blanks between the pits. Preformatted data consisting of sparse pit rows consisting of multiple pits and multiple blanks between pits By forming the preformatted data created by this creating means, by making both sides in the pit length direction longer without changing the position where the pits in the closest packed pit should originally be, The duty ratio of the pits in the dense pit row and the blank portion between them is set so that the blank portion is shorter, and the blank portions of other pit rows are set to the blank length of the closest pit row. Master manufacturing equipment characterized by.