JPH06333246A - Method and device for recording data on optical recording medium - Google Patents

Abstract

PURPOSE:To record pit information precisely with one beam along a spiral locus making (n) a set by reciprocally scanning a recording laser beam by (n-1) tracks while a master disk is rotated once and recording the pit information. CONSTITUTION:The atribute of a sweep signal outputted from a system controller 65 to a synthesis circuit 66 is constituted so that the spot position of the recording laser beam Lw is moved in linear to the inner peripheral side of a glass substrate 41 by (n-1) tracks while the substrate 41 is rotated once, and further, the sweep signal is made a signal waveform with a saw-tooth-wave shape retracing the Lw by (n-1) track pitches whenever the glass substrate 41 is rotated once. Thus, the Lw of one turn whose pitch is equivalent to (n) track pitches irradiates the substrate 41 applied with photoresist, and a resist latent image is formed. Thereafter, the substrate 41 is developed and processed, and a stamper is formed by electroforming. Thus, the pit information making (n) pieces a set is recorded by one laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a pit row formed on a recording surface along a track center scanned by a laser beam, and a pit row composed of a mirror surface, and a data portion is formed at a predetermined clock. A data recording method (laser cutting method) and its apparatus (laser cutting device) used when producing a master of an optical recording medium in which the pit string formed in the data section is read and reproduced as an information signal. ) Concerning.

[0002]

2. Description of the Related Art A recording format of an optical recording medium, for example, an optical recording medium (hereinafter referred to as an optical disk) which is rotationally driven by a CAV (constant angular velocity) system, for example, a recording format of a data section, is as shown in FIG. Track center T
A pit 71 having a pit width d of 0.5 μm and a pit length per clock of 0.86 μm is formed on c with a track pitch Tp of 1.6 μm in the radial direction of the optical disc. Are formed in a format in which the positions in the track direction are aligned. And pit 7
The part without 1 is a mirror surface.

These dimensions are based on manufacturing restrictions and the diameter of the beam spot 72 on the recording surface of the optical disc irradiated with the laser beam emitted from the reproducing laser light source.

In order to increase the recording density of an optical disc,
It is possible to reduce the track pitch Tp, the pit length, and the size of the beam spot 72.

For example, in a magneto-optical disk, there is a restriction that pits recorded based on access unit data and pits of other access units are independent, and all data of access units must be rewritten. ,
The pit length is shortened by so-called overwriting, in which the spot scanning speed is slowed down while maintaining the spot size of the laser beam, and the pit to be formed next overlaps a part of the pit formed previously. To increase the recording density.

That is, the recording density is increased in the track direction,
For example, a magneto-optical disk having a recording density higher than that of a so-called compact disk, which is a read-only optical disk having the same diameter, has been realized.

[0007]

By the way, in order to increase the recording density in the radial direction of the optical disc, for example, it is conceivable to narrow the track pitch Tp. The beam also irradiates the pits 71 of the adjacent tracks to cause crosstalk, which causes a problem that the S / N of the reproduction signal is lowered or, in the worst case, the data cannot be reproduced.

To solve this problem, it is conceivable to simply reduce the track pitch Tp and also reduce the size of the beam spot 72. The size of the beam spot 72 is proportional to the wavelength of the laser beam. Since it is inversely proportional to the numerical aperture NA of the objective lens, there arises a problem that a new laser light source having a short wavelength is newly developed, and an expensive large lens is required to increase the numerical aperture NA.

On the other hand, it is conceivable to maintain the size of the beam spot 72, narrow the track pitch Tp, and narrow the pit width d so as to prevent crosstalk, thereby increasing the recording density. When d is narrowed, there arises a problem that the production yield of an optical disk is reduced, and a conventionally used laser cutting device cannot be used.

Therefore, the present applicant has previously proposed that the pit width d,
We proposed an optical disc that enables high-density recording without changing the pit length and laser beam spot size. This optical disk is an exclusive logical operation type optical disk (generally called an EX-ROM) and this EX-RO.
Wobbled EX-R with wobbled pits formed on M
Proposed and developed as an OM.

The structure of the EX-ROM will be briefly described. The EX-ROM has a track pitch which is 1 / n of the spot size of the reproducing laser beam on the recording surface, and has the previous (n-1) continuous tracks. Data obtained by a predetermined logical operation of the recorded data and the input data is recorded on the next track.

According to this EX-ROM, the pit width d,
The recording capacity can be n times larger than that of, for example, a compact disc having the same size as the conventional one without changing the pit length and the spot size of the reproduction laser beam.

Then, for example, when an EX-ROM having a track pitch of 1/2 the spot size of the reproduction laser beam on the recording surface is produced, that is, the EX-R
When manufacturing a master (stamper) that is the source of OM duplication, the surface of the photoresist coated on the glass substrate is irradiated with a recording laser beam to form a desired pit pattern, and then development processing is performed. In addition, the stamper is manufactured by electroforming, but by irradiating the laser beam,
In the laser cutting step of forming a pit pattern on the photoresist surface, two recording laser beams are separated from each other and irradiated at the same time, thereby forming on the photoresist surface on the glass substrate as shown in FIG. The pit pattern will be formed along a spiral locus of two pairs.

However, in this method, the EX-ROM having a track pitch of 1/3 of the spot size of the reproducing laser beam and the quarter of the spot size are used.
When manufacturing an EX-ROM having a track pitch of 1, the optical system including the laser light source that emits the laser beam for recording becomes complicated, and it is difficult to control or position the irradiation positions of a plurality of laser beams according to the track pitch. A new problem arises.

Further, in the case of the above method, since a plurality of laser beams are radiated at a time in a spatially very narrow range,
There is a problem that the photosensitive state of the photoresist is affected by the adjacent laser beams, and it may not be possible to obtain a resist latent image corresponding to the desired pit shape, and it is difficult to manage the jitter for each laser beam. .

Further, since a plurality of laser light sources and optical modulators corresponding to the number of laser light sources are required, the number of parts as a whole is increased and the laser cutting apparatus becomes expensive.
In addition, there is a disadvantage that the manufacturing cost (cost for laser cutting) also increases.

The present invention has been made in view of the above problems, and an object thereof is 1 / n of the spot size of a reproducing laser beam such as an EX-ROM.
When manufacturing a master of an optical recording medium having a track pitch of 1, the pit information can be formed with high precision with one beam along a spiral locus of a set of n, and laser cutting can be performed. An object of the present invention is to provide a data recording method for an optical recording medium and a data recording device for an optical recording medium, which can realize such cost reduction.

Another object of the present invention is an optical recording medium having a track pitch of 1 / n of the spot size of a reproducing laser beam and having wobbled pits formed in segment units (for example, Wobbled EX-RO
In the case of producing the master of M), with one beam,
Data recording method for optical recording medium and optical recording medium capable of forming pit information with high accuracy along a spiral locus of a set of n lines and realizing cost reduction of laser cutting It is to provide the data recording device of.

[0019]

SUMMARY OF THE INVENTION The present invention is to manufacture a master of an optical recording medium having a track pitch of 1 / n of a spot size of a reproducing laser beam on a recording surface. In a data recording method of an optical recording medium in which pit information is recorded on each track of this master by using a laser beam for recording while rotating, the recording laser beam of the master is rotated while the master rotates once. At the same time as displacing one track pitch in the radial direction,
While the master disk rotates once, the recording laser beam is reciprocally scanned by (n-1) track pitches in the radial direction of the master disk to record the pit information on the master disk.

The backward scanning of the recording laser beam is performed by scanning among the positions corresponding to a plurality of mirror portions formed by only the mirror surface formed on the optical recording medium in the master.
You may make it perform in the position corresponding to at least 1 mirror part. Alternatively, it may be performed from the starting point position where the recording laser beam is positioned each time the master disk is rotated once, and the position before the position corresponding to 1 byte in the track direction.

Also, a master of an optical recording medium (for example, wobbled EX-ROM) having a track pitch of 1 / n of the spot size of the reproducing laser beam and having wobbled pits formed in segment units is used. In the case of manufacturing, when the recording laser beam is reciprocally scanned by (n-1) track pitches in the radial direction of the master, at the same time, the recording laser beam is slightly deflected according to the wobbled pit information. In this way, the pit information (including wobbled pit information) is recorded on the master.

On the other hand, another invention is to manufacture a master of an optical recording medium having a track pitch of 1 / n of a spot size of a reproducing laser beam on a recording surface, wherein the master is rotated while rotating the master. In a data recording device of an optical recording medium for recording pit information on each track of a master by using a laser beam for recording, the laser beam for recording is moved in a radial direction of the master during one rotation of the master. Simultaneously with the displacement means for displacing the track pitch and the displacement operation of the recording laser beam by the displacement means, the recording laser beam is moved in the radial direction (n- 1) An optical deflector for reciprocally scanning a track pitch is provided.

Further, a master of an optical recording medium (for example, wobbled EX-ROM) having a track pitch of 1 / n of the spot size of a reproducing laser beam and having wobbled pits formed in segment units is used. In the case of manufacturing, while the optical deflecting means reciprocally scans the recording laser beam in the radial direction of the master by (n-1) track pitches, the recording laser beam is recorded according to the wobbled pit information. Is configured to be slightly deflected.

[0024]

In the data recording method for the optical recording medium according to the present invention, first, while the master is rotated once, the recording laser beam is displaced by one track pitch in the radial direction of the master. The laser beam for recording is irradiated along a one-turn spiral locus whose pitch is equivalent to one track pitch relative to one rotation of the master.

However, in the present invention, the recording laser beam is further displaced in the radial direction of the master by one track pitch, and at the same time, the recording laser beam is moved in the radial direction of the master (n-1). ) Since the reciprocal scanning (sweep) is performed by the track pitch, the one-turn spiral in which the pitch is equivalent to the n-track pitch relative to the master that makes one rotation by the scanning of the recording laser beam in the forward direction. The recording laser beam is emitted along the trajectory.

Thereafter, the irradiation position of the recording laser beam is moved by one track pitch from the irradiation start position of the recording laser beam toward the center of the master by scanning the recording laser beam in the backward direction. I come to.

Specifically, for example, when a master of an optical recording medium having a track pitch of 1/2 the spot size of a reproducing laser beam is produced, for example, pit information is recorded from the outermost periphery of the master by a laser beam for recording. Considering the case of recording with, in the process of rotating the master once,
First, the pit information of the first track is recorded by the recording laser beam, and when the master disk makes one rotation,
It is located at the starting point of the track. Then, the irradiation position of the recording laser beam is displaced toward the outer peripheral side by one track pitch by the backward scanning (that is, track jump).
However, it is located at the starting point of the second track.

Further, when the master disk makes one revolution, the irradiation position of the recording laser beam is located at the starting point of the fourth track,
By the backward scanning thereafter, the track is displaced to the outer peripheral side by one track pitch (that is, track jump) and is positioned at the starting point of the third track. Similarly, the irradiation position of the recording laser beam is located at the starting point of the (n + 2) th track while the master disk is rotated n times, and is displaced toward the outer peripheral side by one track pitch by the backward scanning thereafter (that is, (Track jump), and the track is positioned at the starting point of the (n + 1) th track.

As described above, according to the data recording method for an optical recording medium of the present invention, an optical recording medium having a track pitch of 1 / n of the spot size of a reproducing laser beam, such as an EX-ROM. In the case of manufacturing the master disc, the pit information can be formed with one beam along a spiral locus of n sets.

That is, for example, an EX-ROM having a track pitch of ⅓ of the spot size of the reproducing laser beam.
Also in the case of manufacturing an EX-ROM having a track pitch of ¼ of the above spot size, it becomes possible to form pit information with one recording laser beam, and a plurality of recording laser beams are used. There is no need to simultaneously emit and form pit information. Therefore, it is not necessary to use a special optical system including a laser light source for emitting a plurality of recording laser beams at the same time, and moreover, it is possible to control and position the irradiation positions of the plurality of recording laser beams according to the track pitch. There is no need to do it.

Further, since it is possible to use only one recording laser beam, it is not necessary to irradiate a plurality of laser beams at one time in a spatially very narrow range, and it is possible to irradiate a plurality of laser beams at the same time. It does not cause deterioration of the photosensitive state of the photoresist (for example, deterioration of the shape of the resist latent image) caused by the above, and it is not necessary to manage the jitter for each laser beam.

Another adverse effect of simultaneously emitting a plurality of laser beams, that is, a plurality of laser light sources and optical modulators corresponding to the number of laser light sources are required, and the total number of parts increases.
There is no problem that the cost for laser cutting becomes high.

Particularly, when the recording laser beam is reciprocally scanned by (n-1) track pitches in the radial direction of the master, at the same time, the recording laser beam is slightly deflected according to the wobbled pit information. , An optical recording medium having a track pitch of 1 / n of the spot size of a reproducing laser beam and having wobbled pits formed in segment units (for example, wobbled EX-RO
In the case of producing the master of M), with one beam,
It is possible to form pit information with high accuracy along a spiral locus of a set of n pieces, and further, it is possible to realize cost reduction for laser cutting.

On the other hand, in a data recording apparatus for an optical recording medium according to another invention, first, while the master is rotated once, the recording laser beam is moved by one track pitch in the radial direction of the master by the moving means. Since it is displaced by that amount, the recording laser beam is normally irradiated along a one-turn spiral locus whose pitch is equivalent to one track pitch relative to one rotation of the master. .

However, in another invention, the recording laser beam is further displaced in the radial direction of the master by one track pitch, and at the same time, the optical deflecting means is used.
The recording laser beam is moved in the radial direction (n-
1) Since the reciprocal scanning is performed by the track pitch, the forward scanning of the recording laser beam causes a one-turn spiral locus in which the pitch is equivalent to the n track pitch with respect to the rotating master. A laser beam for recording is emitted along.

Thereafter, by scanning the recording laser beam in the backward direction, the irradiation position of the recording laser beam is separated by one track pitch from the irradiation start position of the recording laser beam toward the center of the master. Will come to.

As described above, in the data recording apparatus according to the other invention, the data recording method according to the present invention can be easily achieved by the moving means and the light deflecting means, such as an EX-ROM. In the case of producing a master of an optical recording medium having a track pitch of 1 / n of the spot size of a reproducing laser beam, one beam is used to form pit information along a spiral locus of n sets. Can be formed with high precision, and the cost for laser cutting can be reduced.

In particular, while the optical deflecting means reciprocally scans the recording laser beam in the radial direction of the master by (n-1) track pitches, the recording laser beam is changed in accordance with the wobbled pit information. A master disc of an optical recording medium (for example, a wobbled EX-ROM) having a track pitch of 1 / n of the spot size of a reproduction laser beam by finely deflecting and having wobbled pits formed in segment units, for example. In the case of manufacturing a laser beam, it is possible to form pit information with high precision along a spiral locus of a set of n beams with one beam, and to realize cost reduction of laser cutting. it can.

[0039]

EXAMPLES Examples of a data recording method for an optical recording medium according to the present invention will be described below with reference to FIGS. 1 to 16. Before that, optical recording in which data is recorded by this data recording method An example of a medium (hereinafter, simply referred to as an optical disk) will be described with reference to FIGS.

The optical disc 1 on which data is recorded by the data recording method according to this embodiment is of a type that is rotationally driven by, for example, the CAV (constant angular velocity) system, and its recording format is such that one track is composed of a plurality of sectors. Each sector is composed of a plurality of segments. Then, each segment is divided into a servo section Zs having a servo pit and a data section Zd in which original data is recorded. Further, the servo section Zs and the data section Zd are separated by the mirror section Zm which is composed of only the mirror surface (see FIG. 7).

Data part Zd of the optical disc 1 according to this example
As shown in FIG. 5, the recording format in 1 is 1 / the spot diameter of the reproducing laser beam BS on the recording surface.
It has a track pitch of n, and pits are formed based on the recording data obtained by a predetermined logical operation of the data recorded on the previous (n-1) continuous tracks and the input data. ing.

Specifically, in the optical disc 1, two adjacent tracks #n and # n + 1 are simultaneously scanned with respect to the diameter of the spot BS of the reproduction laser beam.
The track pitch Tp is set, and in each of the tracks #n and # n + 1, a pit (non-wobble pit (A)) located on the track center as the pit 11 is located in the + α direction from the track center. By providing pits (wobble pits (B)) and pits (wobble pits (C)) located in the −α direction offset from the track center, and by providing a mirror surface (M) on which the pits 11 are not formed, Four-valued information is represented.

Each of the four-valued information is A, B, C, M
, The track #n as shown in FIG.
Information A₁ , B₁ , C₁ , M₁ , On track # n + 1
Is information A₂ , B₂ , C₂ , M₂ There is a beam
Spot BS simultaneously tracks #n and # n + 1
Information A by being scanned into₁ , B
₁ , C₁ , M₁ And information A₂ , B₂ , C₂ , M₂ Combination of
16 types of data representation by pattern (Pattern P₁ ~
P₁₆) Is possible.

Therefore, the data to be recorded on the track of the optical disc 1 is the data type (A,
B, C, M) is modulated into four values according to
16-valued data of the patterns P _{1 to} P ₁₆ is reproduced.

For example, as shown in FIG. 6A, if pits 11 are formed on tracks # 1, # 2, # 3, and # 4, the pits 11 have a pit width of 0.5 μm, a pit length of 0. 86 μm. In addition, the track pitch Tp is set such that the diameter of the spot BS of the reproduced laser beam to be scanned is 1.5.
~ 1.6μm, which is about 1/2 that of 0.8μ
It is set to m.

The reproduction scanning by the beam spot BS of the reproduction laser beam is performed under the tracking control at the intermediate position of each adjacent track, and accordingly, the tracks # 1 and # 2.
The information of tracks # 1 and # 2 is read by scanning the spot scanning center R ₁ between the beam spot BS and the spot scanning center R ₂ similarly.
There track information # 2 and # 3 is read by scanning, the spot scanning center R ₃ beam spot BS
The information on the tracks # 3 and # 4 is read by scanning.

FIG. 6B shows the information recorded on each of the tracks # 1 to # 4 as A, B, C and M. Then, by scanning R ₁ , R ₂ , and R ₃ , as a combination of the information of FIG. 6B, as shown in FIG.
16 values of _{1 to} P ₁₆ will be extracted. For example, of the information of tracks # 1 and # 2 obtained by scanning R ₁ , information (A, B) is reproduced as pattern P ₂ and information (M, M) is reproduced as pattern P ₁₆ . Then, the recording capacity of the optical disc 1 is dramatically increased as compared with the conventional optical disc that reproduces the binary values of the logic "1" and "0" simply by the presence or absence of the pit 11.

The information of A, B, C, and M is made to correspond to the logic "11", "10", "01", "00" of the recording data, or by the adjacent pair of tracks (that is, , Patterns P _{1 to} P ₁₆ ) are made to correspond to 4-bit data to generate print data by A, B, C, and M.

On the other hand, as shown in FIG. 7, the servo section Zs is arranged so as to be sandwiched by mirror sections Zm formed on both sides in the track direction. The array pattern of the pits (servo pits) 11 forming the servo section Zs is different for every three tracks. Specifically, when the servo section Zs is divided into three parts at equal intervals from the beginning to the end, the first section is the area A, the next section is the area B, and the last section is the area C, the areas are included in each area. The combinations of the pit arrays that are created are divided into three patterns.

That is, in the illustrated example, first, with respect to the first spot scanning center R ₁ , the track # 1 on the outer peripheral side is
Has a pit 11 formed from the area A to the area B, and the inner track # 2 has a pit 11 formed from the area B to the area C. That is, the area B has pits 11 on both the inner and outer circumference sides, the area A has inner pits 11 and the area C has outer pits 11 on the outer circumference side.
When the beam spot BS scans the centers of # 1 and # 2 (first spot scanning center R ₁ ), each pit 11 in the B area is used as a clock mark for clock detection, and each pit 11 in the A area and the C area. Is used as a servo mark for tracking error detection.

Next, regarding the second spot scanning center R ₂ , the track # 2 on the outer peripheral side is B as described above.
The pits 11 are formed from the area to the area C, and the track # 3 on the inner peripheral side has the pits 11 formed in the areas A and C, respectively. That is, the area C has pits 11 on both the inner and outer circumference sides, the area A has inner pits 11 and the area B has pits 11 on the outer circumference side. When the beam spot BS scans the center of # 3 (second spot scanning center R ₂ ), each pit 11 in the C area is used as a clock mark for clock detection, and each pit 11 in the A area and the B area is Used as a servo mark for tracking error detection.

Next, regarding the third spot scanning center R ₃ , the track # 3 on the outer peripheral side is A as described above.
The pits 11 are formed in the area and the area C, respectively, and the track # 4 on the inner peripheral side has the shape in which the pits 11 are formed from the area A to the area B. That is, the area A has pits 11 on both the inner and outer circumference sides, the area B has pits 11 on the inner circumference side, and the area C has pits 11 on the outer circumference side. when # a center of 4 (third spot scanning center R ₃₎ the beam spot BS scans, each pit 11 in the a region is used as clock marks for clock detection, each pit P in the B region and the C region Used as a servo mark for tracking error detection.

A specific tracking servo control method using the pit arrangement of the servo section Zs will be described later in detail.

Next, a manufacturing process of the optical disc 1 according to the above example will be described. The manufacturing process of the optical disc 1 of the above example is roughly divided into a master process (mastering process) and a disc forming process (replication process).

The master process is a process until the metal master (stamper) used in the disc forming process is completed, and the disc forming process uses the stamper to mass-produce the optical disc 1 which is a replica thereof. Is a process.

Specifically, in the master process, a photoresist is applied to a polished glass substrate, and data (pit string information) is recorded on the photoresist by exposure with a laser beam. That is, laser cutting is performed. The data to be recorded must be prepared in advance,
This preparation step is also called premastering.

When the cutting is completed, a predetermined process such as development is performed, and then information is transferred onto the metal surface by, for example, electroforming, and a stamper necessary for duplicating the optical disc 1 is manufactured. .

After that, using the stamper manufactured as described above, information is transferred onto a resin substrate by, for example, an injection method, a light reflecting film is formed on the information, and then a desired disk shape is obtained. The final product (optical disk 1) is completed by performing processing such as processing.

Therefore, in this case, the device used for recording data on the optical disk 1 is a so-called laser cutting device for drawing pit string information with a laser beam on a photoresist formed on a glass substrate.

The laser cutting apparatus according to this embodiment will be described below with reference to FIG.

As shown in the figure, the laser cutting apparatus according to this embodiment includes an optical unit 40 for irradiating a glass substrate 41 having a photoresist coated on its surface with a recording laser beam Lw for cutting, and a glass substrate. It is composed of a drive unit 50 that rotationally drives 41, and a signal processing unit 60 that converts the input data into recording data and controls the optical unit 40 and the drive unit 50.

The optical section 40 converts a laser light source 42 composed of, for example, a He-Cd laser, and a recording laser beam Lw emitted from the laser light source 42 into an ultrasonic signal from a modulating ultrasonic wave generating circuit 63A described later. An acousto-optic effect type optical modulator (hereinafter, simply referred to as AOM) 43A that is modulated (on / off) based on the laser beam Lw modulated by the AOM 43A from a deflection ultrasonic wave generator 63B described later. An acousto-optic effect type optical deflector (hereinafter, simply referred to as AOD) 43B that deflects based on the ultrasonic signal of
It is composed of a prism 44 that bends the optical axis of the laser beam Lw that has passed through the AOD 43B, and an objective lens 45 that collects the laser beam Lw reflected by the prism 44 and irradiates it on the photoresist surface of the glass substrate 41. ing.

The drive unit 50 includes a motor 51 for rotating the glass substrate 41, an FG generation circuit 52 for generating an FG pulse for detecting the rotation speed of the motor 51, and a slide of the glass substrate 41 in the radial direction. And a rotation speed of the motor 51 and the slide motor 53, and the objective lens 45 in the optical unit 40.
And a servo controller 54 for controlling tracking and the like.

The signal processing unit 60 adds, for example, an error correction code or the like to the source data from the computer to generate input data, for example.
A logical operation circuit 62 for generating recording data by performing a predetermined logical operation on the input data from the formatting circuit 61; and the power of the generated ultrasonic signal is modulated based on the recording data from the logical operation circuit 62. The ultrasonic wave generating circuit 63A for modulation, which is output in the following manner, and the synthesizing circuit 6 which synthesizes and outputs the fine deflection signal generated based on the recording data and the sweep signal from the system controller 65 described later.
6 and the frequency of the generated ultrasonic signal are combined by
The deflection ultrasonic wave generator 63B that modulates and outputs the modulated ultrasonic wave based on the combined signal from the CPU, the clock generator 64 that supplies the clock signal to the logical operation circuit 62, and the servo controller 54 based on the supplied clock signal. And a system controller 65 for controlling the above.

The system controller 65 outputs the phase difference signal between the FG pulse from the FG generation circuit 52 and the clock signal from the clock generator 64 to the servo controller 5.
Supply to 4. The servo controller 54 generates a rotation servo signal based on the phase difference signal from the system controller 65, supplies this rotation servo signal to the motor 51, and controls so that the rotation speed of the motor 51 becomes constant.

At the same time, the servo controller 54
Based on the phase difference signal from the system controller 65, as shown in FIG.
Takes the elapsed time from the time when the rotating at a constant speed (that is, the start of the constant speed rotation) (the numbers on the horizontal axis indicate the number of rotations of the glass substrate 41), and when the number of track pitches is taken on the vertical axis, While the glass substrate 41 makes one rotation, the objective lens 45 sends a drive signal for linearly moving toward the inner peripheral side of the glass substrate 41 by one track pitch (0.8 μm in this example). The drive signal is generated and supplied to the slide motor 53 to control the movement of the glass substrate 41 so that the objective lens 45 relatively moves by one track pitch each time the glass substrate 41 makes one rotation.

Further, the system controller 65 uses the clock signal from the clock generator 64 and the FG generation circuit 52.
A sweep signal for supplying to the AOD 43B is generated based on the FG pulse from This sweep signal is AOD4
2B by the deflection action on the recording laser beam Lw caused by the supply of the sweep signal to 3B.
As shown in (b), when the elapsed time from the start of the constant speed rotation of the glass substrate 41 is plotted on the horizontal axis and the track pitch number is plotted on the vertical axis, the recording substrate is recorded during one rotation of the glass substrate 41. The spot position of the laser beam Lw is set on the glass substrate 41.
1 track pitch toward the inner circumference of (in this example,
0.8 μm), and has a sawtooth-shaped signal waveform that linearly moves relative to each other and further retraces the recording laser beam Lw by one track pitch each time the glass substrate 41 makes one revolution.

On the other hand, the input data to which the error correction code and the like have been added by the formatting circuit 61 is supplied to the logical operation circuit 62 and logically converted as recording data. That is, the logical operation circuit 62 has a built-in memory having a storage capacity capable of storing at least one track of recorded data, and the data (A, B, C, M recorded on the preceding track of the glass substrate 41 is incorporated therein. 4 value data)
And the recording data (A, B, C) to be recorded on the next track by performing a predetermined logical operation on the stored recording data and the input data on the next track input from the formatting circuit 61. , M
4 value data of) is generated.

Then, this recording data is supplied to the modulating ultrasonic wave generator 63A and the synthesizing circuit 66, respectively. The modulation ultrasonic generator 63A modulates the power of the generated ultrasonic signal based on the recording data, and supplies the modulated ultrasonic signal to the AOM 43A, so that the recording laser beam from the laser light source 42 is generated. The light intensity of Lw is controlled to be turned on at the bit timing when the recording data is A, B, or C, and off at the bit timing when the recording data is M.

Of the supplied recording data, the synthesizing circuit 66 makes a fine deflection signal whose amplitude is, for example, + α at the bit timing when the recording data is B, and -α at the bit timing when the recording data is C. Is generated, and the fine deflection signal and the sweep signal from the system controller 65 are combined (superposed) and output to the deflection ultrasonic wave generator 63B as a combined signal.

The deflection ultrasonic wave generator 63B modulates the frequency of the generated ultrasonic wave signal based on the level of the combined signal from the combining circuit 66, and the modulated ultrasonic wave signal A
By supplying to the OD 43B, the recording laser beam Lw whose intensity is modulated by the AOM 43A is supplied to the glass substrate 4.
While 1 rotates once, the glass substrate 41 is deflected toward the inner peripheral side by one track pitch, and the deflection direction of the recording laser beam Lw is + α at the bit timing when the recording data is B or C. Drive is controlled so that the direction is −direction or −α direction.

As a result, in this laser cutting device, the spot position of the recording laser beam Lw changes every time the glass substrate 41 makes one rotation by the movement operation of the glass substrate 41 by the slide motor 53.
It is displaced by one track pitch in the radial direction of the glass substrate 41, and at the same time, the recording laser beam L by the AOD 43B.
By the deflection operation of w, the recording laser beam Lw
Is swept by one track pitch in the radial direction of the glass substrate 41, so that as shown in FIG.
During the deflection period Ta of the recording laser beam Lw of B, the spot position of the recording laser beam Lw jumps by two track pitches every time the glass substrate 41 makes one rotation.

That is, as shown in FIG. 3, the glass substrate 41
, The pitch T is equal to 2 track pitch
The recording laser beam Lw is emitted along the spiral trajectory of the turn, and a resist latent image of pits based on the recording data is formed on the photoresist surface along the spiral trajectory. Then, during the blanking period Tb of the AOD 43B thereafter, the recording laser beam L
The spot position of w is returned by one track pitch in the outer peripheral direction.

More specifically, the glass substrate 41 is 1
In the rotating process, first, the recording laser beam Lw
At the time when the pit information of the first track is recorded and the glass substrate 41 makes one rotation, the irradiation position of the recording laser beam Lw is located at the starting point of the third track, and by the subsequent blanking deflection, It is displaced to the outer peripheral side by one track pitch (that is, a track jump) and is positioned at the starting point of the second track.

Further, when the glass substrate 41 makes one rotation, the irradiation position of the recording laser beam Lw is located at the starting point of the fourth track, and is displaced to the outer peripheral side by one track pitch due to the subsequent blanking deflection ( That is, track jump)
However, it is located at the starting point of the third track. Similarly, every time the glass substrate 41 rotates n times, the irradiation position of the recording laser beam Lw is located at the starting point of the (n + 2) th track, and is displaced to the outer peripheral side by one track pitch due to the subsequent blanking deflection. (That is, the track jump), and the track is positioned at the starting point of the (n + 1) th track.

When the laser cutting process by the above laser cutting device is completed, a developing process, an electroforming process, etc. are then performed to manufacture a stamper, and the optical disk 1 according to the above example is mass-produced by using the manufactured stamper. Produced.

As described above, according to the optical disk data recording method (cutting method by the laser cutting device) of the present invention, an optical disk having a track pitch Tp of ½ of the spot diameter of the reproducing laser beam on the recording surface. In the case of manufacturing one master (stamper), one beam Lw forms a spiral locus with one beam Lw on a glass substrate 41 coated with a photoresist which is a base for manufacturing the stamper. Along with this, pit information (resist latent image) can be formed.

Therefore, even when an optical disc having a track pitch Tp of 1/3 of the spot diameter of the reproducing laser beam or an optical disc having a track pitch of 1/4 of the spot diameter is produced, one recording Since the pit information can be formed by the laser beam Lw, it is not necessary to emit a plurality of recording laser beams at the same time to form the pit information. Therefore, it is not necessary to use a special optical system including a laser light source for emitting a plurality of recording laser beams at the same time, and moreover, it is possible to control and position the irradiation positions of the plurality of recording laser beams according to the track pitch. There is no need to do it.

As an example, when a master disc (stamper) of an optical disc having a track pitch Tp that is ¼ of the spot diameter of the reproducing laser beam is produced, the attributes of the sweep signal output from the system controller 65 to the synthesizing circuit 66. As shown in FIG. 4A, the horizontal axis indicates the glass substrate 4
When the elapsed time from the start of the constant speed rotation of 1 is taken and the track pitch number is taken on the vertical axis, the spot position of the recording laser beam Lw is set within the glass substrate 41 while the glass substrate 41 makes one rotation. 3 track pitches (2.4 μm in this example) are linearly moved toward the circumferential side,
Further, each time the glass substrate 41 makes one rotation, the recording laser beam Lw has a sawtooth signal waveform that retraces by three track pitches.

By doing so, as shown in FIG. 4B, the spot position of the recording laser beam Lw is changed every time the glass substrate 41 makes one rotation in the deflection period Ta of the AOD 43B with respect to the recording laser beam Lw. Will jump four track pitches.

That is, the glass substrate 41 is irradiated with the recording laser beam along a one-turn spiral locus having a pitch equal to four track pitches, and the recording data is recorded along this spiral locus. Therefore, a resist latent image of pits is formed on the photoresist surface. Then, the subsequent blanking period T of AOD43B
In b, the spot position of the recording laser beam Lw is returned by 3 track pitches in the outer peripheral direction.

More specifically, the glass substrate 41 is 1
In the rotating process, first, the recording laser beam Lw
At the time when the pit information of the first track is recorded and the glass substrate 41 makes one rotation, the irradiation position of the recording laser beam Lw is located at the starting point of the fifth track, and by the subsequent blanking deflection, It is displaced by 3 track pitches toward the outer circumference (that is, a track jump) and is positioned at the starting point of the second track.

Further, when the glass substrate 41 makes one rotation, the irradiation position of the recording laser beam Lw is located at the starting point of the sixth track, and by the subsequent blanking deflection, it is displaced to the outer peripheral side by three track pitches ( That is, track jump)
However, it is located at the starting point of the third track. Similarly, every time the glass substrate 41 rotates n times, the irradiation position of the recording laser beam Lw is located at the starting point of the (n + 4) th track, and is displaced to the outer peripheral side by 3 track pitches due to the flyback deflection thereafter. (That is, the track jump), and the track is positioned at the starting point of the (n + 1) th track.

Further, in the laser cutting apparatus according to this embodiment, since only one recording laser beam Lw is required, it is necessary to irradiate a plurality of laser beams at one time in a spatially very narrow range. Disappears. As a result, the deterioration of the photosensitivity of the photoresist (for example, the deterioration of the shape of the resist latent image) caused by the simultaneous irradiation of a plurality of laser beams is not caused, and it is not necessary to manage the jitter for each laser beam. .

Further, another adverse effect of simultaneously emitting a plurality of laser beams, that is, a plurality of laser light sources and optical modulators corresponding to the number of laser light sources are required, and the total number of parts increases.
There is no problem that the cost for laser cutting becomes high.

Particularly, when the recording laser beam Lw is swept in the radial direction of the glass substrate 41 by (n-1) track pitches, at the same time, the recording laser beam Lw is slightly deflected according to the wobble pit information. In the case of manufacturing a stamper of the optical disc 1 having a track pitch of 1 / n of the spot diameter of the reproducing laser beam and having wobbled pits formed in segment units, for example, one recording laser beam Lw is used. , It is possible to form pit information with high accuracy along a spiral locus of a set of n pieces, and it is possible to reduce the cost required for laser cutting.

The timing of the blanking deflection of the recording laser beam Lw by the AOD 43B is, for example, as shown in FIG. 7, of the left and right mirror sections Zm that spatially separate the servo section Zs and the data section Zd. It is arranged after the servo section Zs and is performed in a portion corresponding to a mirror section Zm (having a bit length of 8 bits, that is, a length corresponding to 1 byte) used for focus servo control. By performing the blanking deflection at this timing, it is possible to avoid the disadvantage that the pits to be formed in the data section Zd or the servo section Zs are not formed by the blanking deflection.

Next, a method of reproducing data from the optical disc 1 according to the above example will be described with reference to FIGS.
When data is reproduced from the optical disc 1, a reproduction laser beam having a spot diameter n times the track pitch Tp is used.

For example, in the data reproduction on the optical disc 1 shown in FIG. 5, the spot diameter is the track pitch T.
By irradiating a reproducing laser beam having a diameter twice as large as p, the information of the patterns P _{1 to} P ₁₆ shown in FIG. 5 is accurately extracted from the information of the diffracted light obtained by the simultaneous scanning of two tracks. It can be achieved by doing.

FIG. 8 shows the structure of a reproducing apparatus suitable for this reproducing method. As shown in the figure, this reproducing apparatus irradiates the optical disc 1 according to the above-mentioned example with a laser beam L, and the recording surface 1
The optical pickup 2 is configured to detect the light amount of the reflected light Lr reflected by a, and the signal processing unit 3 that reproduces data from the reproduction signal from the optical pickup 2.

The optical pickup 2 includes a laser light source 21 and
A collimator lens 22 that collimates the emitted light (reproducing laser beam) L from the laser light source 21 and an objective lens 23 that condenses the collimated light from the collimator lens 22 and irradiates the recording surface 1a of the optical disc 1. A beam splitter 24 disposed in the optical path between the collimator lens 22 and the objective lens 23 and separating the reflected light Lr reflected by the recording surface 1a of the optical disc 1; A photoelectric conversion element (hereinafter referred to as a photodetector) that detects the amount of the reflected light Lr 2
5, the beam splitter 24 and the photodetector 25 in the optical path, and the beam splitter 2
And a condenser lens 26 for condensing the reflected light Lr separated by 4.

The optical pickup 2 has almost the same structure as the conventional optical pickup 2 used in a compact disc reproducing apparatus or the like, except that the track pitch Tp of the optical disc 1 is emitted from the laser light source 21. The spot diameter is 1/2 of the reproduction laser beam L, and as shown in FIG. 5, the beam spot BS simultaneously scans adjacent tracks #n and # n + 1 (hereinafter, the width scanned by the spot BS is scanned. Tracking servo control is applied as described below).

The laser light source 21 of the optical pickup 2 is composed of, for example, a semiconductor laser and emits a reproducing laser beam L having the same wavelength as that of the conventional optical pickup 2. The collimator lens 22 causes the reproducing laser beam L from the laser light source 21 to enter the beam splitter 24 as parallel light.

The beam splitter 24 is composed of, for example, a half mirror, and allows the reproducing laser beam L from the laser light source 21 to pass through the objective lens 23. Objective lens 2
Reference numeral 3 has an aperture ratio NA equivalent to that of a conventional optical pickup, and collects the reproduction laser beam L from the laser light source 21 that has passed through the beam splitter 24 and irradiates the recording surface 1a of the optical disc 1.

The condenser lens 26 is composed of a cylindrical lens for obtaining a focus error signal by the astigmatism method, for example, and the reflected light Lr is reflected by the photodetector 25.
Focus on the light receiving surface of.

As shown in FIG. 9, the photodetector 25 has four light receiving regions 25a, 25b and 25c.
And 25d. This photo detector 2
Reference numeral 5 denotes the above-mentioned four regions 25a, 25 constituting the light receiving surface.
b, 25c and 25d, two regions 25a and 25d
Reflected light Lr diffracted by, for example, the pit 11 on the outer peripheral side with respect to the spot scanning center on the recording surface 1a of the optical disc 1 is incident on the other two areas 25b and 25.
c is an arrangement relationship in which the reflected light Lr diffracted by the pits 11 on the inner peripheral side is incident on the basis of the spot scanning center on the recording surface 1a of the optical disc 1, and each region 25
Detection signals S _A , S _B , S _C and S based on the light amount of the reflected light Lr photoelectrically converted by a, 25b, 25c and 25d.
_D is output from each output terminal.

On the other hand, the signal processing unit 3 has four detection signals S _A , S _B , S _C and S _D from the photo detector 25.
, And the amplified four detection signals S _A ,
An arithmetic circuit 30 for generating an RF signal and a push-pull signal from S _B , S _C and S _D, and an RF from the arithmetic circuit 27.
A signal discriminating circuit 31 which reproduces 16-valued data based on the signal and the push-pull signal and outputs the reproduced data.
Have.

Further, the arithmetic circuit 30 has four detection signals S _A , S _B , S _C and S _D from the photo detector 25.
From the above, for example, astigmatism information is calculated and output as a focus error signal, and at the same time, the four detection signals S _A ,
A tracking error signal of a sampled servo system, which will be described later, is extracted from S _B , S _C and S _D and output. These focus error signal and tracking error signal are
It is supplied to the servo controller 33.

In addition, R generated by the arithmetic circuit 30 is
The F signal is also supplied to the PLL circuit 32. This PLL
The circuit 32 is a circuit that generates a clock signal from the RF signal from the arithmetic circuit 30, and the clock signal generated by the PLL circuit 32 is supplied to the system controller 34. The system controller 34 is the PLL
Based on the clock signal from the circuit 32, operation control of the servo controller 33, the signal discrimination circuit 31 and the like, which will be described later, is performed.

The servo controller 33 sets the objective lens 23 in the optical pickup 2 in the tracking direction based on the focus error signal and the tracking error signal from the arithmetic circuit 30, the track jump from the system controller 34, the spindle rotation command information, and the like. A biaxial mechanism that holds the optical pickup 2 so that it can be driven in the focus direction and a sled mechanism that moves the optical pickup 2 in the radial direction of the optical disk are driven, and the spindle motor 35 is rotationally driven by, for example, the CAV method.

Here, the essential parts for extracting the 16-value data and the tracking error signal, that is, the configurations of the arithmetic circuit 30 and the signal discriminating circuit 31 will be described with reference to FIG.

The arithmetic circuit 30 includes the photodetector 25.
Four regions 25a, 25b, 25c and a light receiving surface
Detection signals from two areas 25a and 25d
Issue S _A And S_D The sum of the signal levels of the
Issue I₁ Adder 30a for outputting as
Detection signal S from 25b and 25c_B And S_C Each signal of
The sum of the levels is taken and the second addition signal I₂ Output as
2 adder 30b and the first adder from the first adder 30a
Addition signal I₁ And the second addition signal from the second adder 30b
Issue I₂ RF signal S_RFAs
The third adder 30c for outputting and the above first and second adders
Arithmetic signal I₁ And I₂ Of each signal level of
And a subtractor 30d for outputting as a pull signal Spp.
It

Therefore, the two detection signals S _A and S _D from one of the regions 25a and 25d of the photodetector 25 are detected.
Are added by the first adder 30a to generate a first addition signal I
_The two detection signals S _B and S _C from the other regions 25b and 25c of the photodetector 25 are added by the second adder 30b and output as the _second addition signal I _2. . The first and second addition signals I ₁ and I ₂ are added to each other by the third adder 30c and output as the RF signal S _RF , and the subtractor 3
They are subtracted from each other by 0d and output as a push-pull signal Spp.

The arithmetic circuit 30 also includes a first sample-hold circuit (hereinafter simply referred to as S / H circuit) 30e for sampling and holding the RF signal S _RF from the third adder 30c at a predetermined timing. , A tracking error signal generation circuit 30f that generates a tracking error signal based on the sample and hold signal from the first S / H circuit 30e, and an RF signal S _RF from the third adder 30c.
Has a second S / H circuit 30g for sampling and holding at a predetermined timing and outputting it as a clock generation signal.

The tracking error signal generation circuit 30
f is R according to the reproduction timing of the servo mark described later.
A tracking error signal is generated from the F signal.

On the other hand, the signal discriminating circuit 31 digitally converts the RF signal S _RF and the push-pull signal Spp from the arithmetic circuit 30 and outputs them as RF signal data and push-pull signal data, respectively. / D
The converters 31a and 31b and these first and second A /
It has a 16-value conversion circuit 31c for discriminating the 16 values (patterns P _{1 to} P ₁₆ ) described above by matrix calculation of the values of the RF signal data and the values of the push-pull signal data supplied from the D converters 31a and 31b. .

A data extraction method by the arithmetic circuit 30 and the signal discriminating circuit 31 having such a configuration will be described below.

First, as a premise of this, as shown in FIG. 10, a mirror surface M ₁ and pits A ₁ , B ₁ , C _{1 are provided} on the track #n with respect to the spot BS of the reproducing laser beam L.
And the mirror surface M ₂ and the pits A ₂ , B ₂ and C ₂ are present on the track # n + 1.

One region 25a of the photo detector 25
And 25d, that is, the signal level of the first addition signal I ₁ from the first adder 30a in the arithmetic circuit 30, and the diffraction levels obtained by the other regions 25b and 25c of the photodetector 25, that is, the arithmetic operation. The signal level of the second addition signal I ₂ from the second adder 30b in the circuit 30 is as shown in FIG.
This corresponds to 0, α, 2α and 3α, respectively.

The signal levels (diffraction level) of the first addition signal I ₁ and the second addition signal I ₂ are determined by the patterns P _{1 to} P.
Fig. 5 (c) shows each of ₁₆ items.
Then, the RF signal S _RF is the first and second addition signals I ₁
The signal level (diffraction level) as the RF signal S _RF is obtained by the sum of the respective signal levels of I and I _2.
5 has a level distribution of 0 to -6 according to the patterns P _{1 to} P ₁₆ , as shown in FIG. 5D, while the first and second addition signals I ₁ and I ₂ Push-pull signal Spp obtained by the difference between the respective signal levels of
Signal level (diffraction level) will be indicated as shown in FIG. 5 (e), the level distribution of up to -3 + 3 in accordance with the pattern P ₁ to P _16.

FIGS. 11A and 11B show the RF signal S _RF (degree of modulation) and the push-pull signal Spp. In FIGS. 11A and 11B, the vertical axis represents 0.0 and the value calculated as the mirror level. The beam position on the horizontal axis indicates the position where the beam spot BS has moved in the reproduction scanning direction with the pit center at 0.0 as shown in FIG.

Therefore, by extracting data with the reproduction clock corresponding to the beam position 0.0, information is extracted in the level range from 0 to -0.65 as the RF signal S _RF , and the push-pull is performed. Signal Sp
Information is extracted in the level range of about -0.3 to +0.3 as p.

As described above, both the RF signal S _RF and the push-pull signal Spp can be level-determined in seven types of divisions, and each of the patterns P _{1 to} P ₁₆ is shown in FIG.
As shown in 3, the RF signal S _RF and the push-pull signal Sp
Since it is located independently on the information map corresponding to the level division of p, this information map is used as the hexadecimalization circuit 3
1c is logically stored in a predetermined array variable area of the memory incorporated in 1c, and further, based on the values of the RF signal data and the push-pull signal data, referring to this information map, patterns P _{1 to} P By registering an algorithm for determining ₁₆ as a program, it is possible to easily determine which _{one of} the patterns P _{1 to} P ₁₆ is currently reproduced and scanned from the value of the RF signal data and the value of the push-pull signal data. It becomes possible to do.

For example, the value of the RF signal data is -0.2.
(That is, 2 in the information map) and the push-pull signal data value is 0.0 (0 in the information map), the hexadecimalization circuit 31c discriminates the pattern P _7, and the track #n is + α. Wobbled pit 11
The information B and the track # n + 1 are reproduced as the information C by the wobbled pit 11 of −α.

By storing the information map as shown in FIG. 13 in the memory incorporated in the hexadecimalization circuit, the value of the RF signal data and the value of the push-pull signal data are stored as described above. It is possible to discriminate the patterns P _{1 to} P ₁₆ from this, but for this purpose, as shown in FIG. 13, threshold values SL _{R1 to} SL _R6 for selecting the values of the RF signal data into the levels of 0 to 6 are used. And threshold values SL _{P1 to} SL _P6 for selecting the values of the push-pull signal data into the levels of -3 to +3.

If the reflectance is always constant for each optical disk 1, and if no intersymbol interference is observed on the optical disk 1, the threshold values SL _{R1 to} SL _R6 and the threshold values SL _{P1 to} SL _P6 are Although it can be set in advance based on experimental data or the like, actually, the values of the RF signal data and the values of the push-pull signal data based on the information of A, B, C, and M fluctuate due to intersymbol interference or the like. It is possible.

Therefore, in the predetermined area (for example, the servo section Zs) of the predetermined cycle on the optical disc 1, the data shown in FIG.
The 6 patterns of information are recorded in advance as the reference information as they are, and at the time of reproduction, the optimum threshold is determined from the value of the RF signal data and the value of the push-pull signal data obtained when each pattern in the reference information is reproduced. The values SL _{R1 to} SL _R6 and the threshold values SL _{P1 to} SL _P6 are calculated and stored in the memory incorporated in the 16-value quantization circuit 31c. This enables accurate 16-value discrimination.

Further, by recording this reference information in the servo section Zs of the so-called sample servo system (the head area of each segment in the sector dividing the track), tracking servo information can be obtained.

In this example, the beam spot BS is
Tracking is controlled at the middle position of the pair of tracks
At this time, the pattern in FIG.
P ₁ , Pattern P_Four And pattern P₁₃(All A information
The playback timing of the non-wobbled pit 11) becomes
The sampled RF signal S_RFDepending on the value of
Re-phase tracking control becomes possible.

The three-phase tracking control will be described below with reference to FIGS. 14 to 16.

The arithmetic circuit 30 and the signals shown in FIG. 9 described above.
With the configuration of the discrimination circuit 31, an RF signal is generated by reproduction scanning.
S_RFIs extracted, its RF signal S_RFIs the first S /
It is also supplied to the H circuit 30e and the second S / H circuit 30g.
It In the second S / H circuit 30g, for example, the servo of FIG.
The RF signal S is reproduced at the reproduction timing of the area A in the portion Zs. _RF
Is sampled and used as a clock generation signal P
It is supplied to the LL circuit 32 (see FIG. 8).

On the other hand, based on the clock signal generated by the PLL circuit 32, sampling clocks at the timings of the areas A, B and C are generated and supplied to the first S / H circuit 30e. The first S / H circuit 30e is
The RF signal S based on the supplied sampling clock
Three-phase signals RFA, RFB, RFC obtained by sampling _RF and having different phases as shown in FIG.
Is supplied to the tracking error signal generation circuit 30f.

Tracking error signal generation circuit 30f
Is the first S / H circuit 30 as shown in FIG.
The differential amplifiers 80a, 80b and 80c for obtaining the difference between the RF signals RFA, RFB and RFC from e, the multiplexer 81 for switching and selecting the outputs of the differential amplifiers 80a, 80b and 80c, and the differential amplifier 80.
Comprised of comparators 82a, 82b and 82c that detect the polarities of the outputs of a, 80b and 80c, and a logical operation circuit 83 that controls the multiplexer 81 by a predetermined logical operation for each output of these comparators 82a, 82b and 82c. Has been done.

The differential amplifier 80a is, for example, as shown in FIG.
As indicated by a broken line in FIG. 5 (b), the tracking error signal T is obtained by subtracting the RF signal RFB from the RF signal RFC.
RA is generated, and the differential amplifier 80b subtracts the RF signal RFC from the RF signal RFA to obtain the tracking error signal T.
The RB is generated, and the differential amplifier 80c subtracts the RF signal RFA from the RF signal RFB to obtain the tracking error signal T.
Generate RC.

Therefore, these tracking error signals TRA, TRB, and TRC are sine waves, and the phases thereof are different from each other by 120 °, and the RF signals RFA and RF.
The signal has a phase advanced by 90 ° with respect to B and RFC. Each tracking error signal TRA, TRB, TR
C is a multiplexer 81 and comparators 82a and 8a
2b and 82c.

Comparators 82a, 82b and 82c
15A and 15B respectively detect the polarities of the tracking error signals TRA, TRB, and TRC as shown in FIG. 15C, and, for example, the polarity signal PA, which becomes a logic “1” at a positive level,
PB and PC are generated and these are supplied to the logical operation circuit 83. The logical operation circuit 83 is based on the equations (1) to (3) shown below and, for example, as shown in FIG.
Control signals CA, CB, CC whose phases are different from each other by 120 °
To calculate.

When the control signal CA is logic "1", the tracking error signal TRA is selected, and when the control signal CB is logic "1", the tracking error signal T is selected.
When RB is selected and the control signal CC is logic "1", the multiplexer 81 is controlled so that the tracking error signal TRC is selected.

Ca = Pc ∩ INV (Pb) ………… (1)

Cb = Pa∩INV (Pc) ………… (2)

Cc = Pb ∩ INV (Pa) ............ (3)

In these equations (1) to (3), the symbols “∩” and “INV ()” are the logical product,
Means negative logic.

As shown by the solid line in FIG. 15B, the multiplexer 81 outputs a tracking error signal in which the three-phase tracking error signals TRA, TRB and TRC whose phases are different from each other are periodically switched. This tracking error signal is supplied to the optical pickup 2 shown in FIG. 8 after being subjected to phase compensation processing in the servo loop, and the two-axis mechanism causes the objective lens 23 to detect the tracking error signal in the radial direction of the optical disc 1. It is moved so that the level becomes zero.

By such tracking servo control, reproduction scanning is performed with the intermediate position of the adjacent pair track as the tracking center, and as described above, 16-valued pattern information by the pair track is extracted. .

By the way, when the wobbled pits 11 are provided as the information B or the information C like the optical disc 1 according to the above-mentioned example, it is possible to perform so-called detrack tracking by using these.

That is, as shown in FIG. 16, the servo pits 11s formed by the non-wobbled pits described above are set separately from a part of the reference information or the reference information, and the servos formed by the wobbled pits are set in the servo section Zs. Set pits 11SW + and 11SW-.

That is, the servo pits 11S are formed at the positions PS _{A +} , PS _{B +} , PS _{C +} by using the patterns P ₆ , P ₈ , P ₁₄ of wobbled pits of + α deviation, which are the information B.
W ₊ is provided, and the patterns P ₁₁ , P ₁₂ , P ₁₅ by wobbled pits of −α deviation that become the information C are used, and servo pits 11SW are provided at the positions PS _A− , PS _B− , PS _C−.
- the provision.

In this case, the positions PS _{A +} , PS _{B +} , P
If the tracking error signal is generated from the RF signal from the servo pit 11SW ₊ of S _{C +} as described above, the tracking control deviated by + α from the original tracking center (spot scanning center) indicated by the alternate long and short dash line.

Further, the positions PS _A- , PS _B- , PS _C-
If the tracking error signal is generated from the RF signal from the servo pits 11SW ₋ as described above, the tracking control deviates from the original tracking center (spot scanning center) by −α.

By executing this digital track tracking, it is possible to improve the discrimination efficiency of 16-valued data even with the influence of crosstalk, for example.
That is, it can be used for the verify operation.

For example, when a certain pair track is reproduced
Pattern P for the obtained data ₁ Or P₃ And
Suppose it was difficult to determine whether Where + α detra
The actual pattern P₁ 
(A₁ , A₁ ), Information A is read as information C
Therefore, the pattern P₁₁(C₁ , C₁ ) Is determined.
Also, the actual pattern P₃ (A₁ , C₂ ) Is information A
Read as information C, read information C as information M
Because it is rare, pattern P₁₂(C₁ , M₂ ) As
Be done.

Furthermore, reproduction is performed in the -α detrack state.
Therefore, the actual pattern P₁(A₁ , A₁ ) Is the emotion
Since the information A is read as the information B, the pattern P₆ 
(B ₁ , B₁ ) Is determined. Also the actual putter
P₃ (A₁ , C₂ ), Information A is read as information B
In rare cases, the information C is read as the information A.
P_Five (B₁ , A₂ ) Will be determined as.

That is, when the pattern P ₁ or P ₃ cannot be discriminated by the normal tracking reproduction, or when the accuracy is low, the reproduction is performed in the + α and −α detrack states, and the + α detrack is performed. When the pattern P _{12 is} reproduced and the pattern P ₅ is reproduced by -α detrack, the pattern can be determined to be the pattern P ₃ . Similarly, in the + α detrack reproduction, the patterns P ₁₁ , -α
When the pattern P ₆ is obtained by the detrack reproduction, it can be determined that the pattern is the pattern P ₁ .

As described above, by discriminating data using the information map as shown in FIG. 13 by the + α detrack reproduction and the information map by the −α detrack reproduction, the redundancy is improved and, for example, the influence of crosstalk is also caused. You can cancel.

Regarding the focus state, even if the ± αF defocus state is considered with the proper focus state set to zero, it can be similarly applied to the Belphi operation.

For example, even in the defocused state, the pattern P
_When the levels of the push-pull signals of ₁ , P ₇ , P ₁₆ , and P ₁₀ do not change, but the degree of modulation decreases (for example, pattern P
₁₀ occurs at level 6 → 5) or rises (for example, pattern P ₇ attains level 2 → 3), that is, + αF
Since an information map can be formed by-and -αF defocus, it can be used in the same manner as above.

By the way, in this example, the reproduction scanning is
As shown by R ₁ , R _2, ... In FIG. 6A, one track is always reproduced and scanned twice. Therefore, when the influence of crosstalk is considered, the verify operation can be performed by referring to the data obtained by the previous scan.

For example, considering the track # 2 in FIG. 6, in the 16-value quantization circuit 31c, the spot scanning center R ₁
The 4-level reproduction information of track # 2 obtained by scanning the track # 2 is temporarily stored in the memory, and the 4-level reproduction information of track # 2 obtained by scanning the spot scanning center R ₂ is When it is input, it is compared with the reproduction information by scanning to the spot scanning center R ₁ stored in the memory to confirm whether or not they match, and if they match, the reproduction information of the track # 2 is completed. To make a decision.

Similarly, the four-valued reproduction information of the track # 3 obtained by scanning the spot scanning center R ₂ and the four-valued reproduction information of the track # 3 obtained by scanning the spot scanning center R ₃ are obtained. The reproduction information of track # 3 is determined from the reproduction information. Then, after confirming that the recording data has been correctly extracted in this way, the data is logically converted into 16-valued data based on the information map. By performing such a verify operation, it is possible to reduce or eliminate a data reproduction error.

Further, it is conceivable to add the reproduction information by ± α detrack scanning described above to the verify operation to perform the verify operation. For example, track #
For # 2, by scanning with + α detracking with respect to the spot scanning center R ₁ (using the information map of + α detracking described above), it is possible to reduce the influence of crosstalk due to track # 3, and By scanning the spot scan center R ₂ by −α detrack (using the above-described −α detrack information map), the influence of crosstalk due to track # 1 can be reduced.

Thus, the optical disc 1 according to the above example
Since it becomes possible to cancel the crosstalk and reproduce the data by the above verify operation, it is also possible to set the track pitch to be substantially narrowed by ± α. That is, if there is a margin in the number of rotations of the disk and double reading with detrack tracking is possible, higher density recording is realized.

In the example described above, the wobbled pits having a deviation amount of ± α are set. However, when the S / N is good, the wobbled pits of ± α are set. In addition to the above, wobbled pits with deviation amounts of ± β and ± γ may be set.

For example, in this case, as the pit information recorded on the track, in addition to the non-wobbled pits (the above information A), the wobbled pits of ± α (the above information B and C), and the mirror surface M, ± β wobbled pits (above information D and E) and ± γ wobbled pits (above information F,
It becomes the 8 value of G).

As a result, it is possible to set 6 in adjacent pair tracks.
Since four patterns of data are recorded, 64-value data can be reproduced per 1-bit timing.
In this case, even if the pit length is 0.8 μm, a high density (32 times that of the current compact disc) substantially equivalent to 0.0125 μm / bit is realized.

In the above example, the pattern is extracted by using two tracks as a pair, but the track pitch and the spot size are set so that three or more tracks are simultaneously irradiated by the spot of the reproducing laser beam. Etc., and each track precedes the input data by 2
The record data may be generated by a logical operation with the record data in the tracks of one or more.

By the way, regarding the reproduction scanning, the scanning of FIG.
Pot scanning center R₁ , R₂ , R₃ ... each next to
In addition to scanning between adjacent tracks, for example during spot scanning
Heart R ₁ , R₃ ... and so on, one track is one
It can also be set to scan only once.

Further, in the optical disc 1 according to the above-mentioned example, the case where the information is recorded in the pit form is shown, but the present invention can be applied to the one in which the information is recorded by the so-called groove. In this case, on-track grooves and wobbling grooves having a deviation amount such as ± α are used to record three or more values.

Further, in the laser cutting apparatus according to the above-described embodiment, an example in which the laser cutting apparatus is applied to the reproduction-only optical disc 1 is shown. However, in addition to this, for example, each segment has pit string information, and information is reproduced by the Kerr effect. It can also be applied to a magneto-optical disk for reading.

[0158]

As described above, according to the data recording method of the optical recording medium of the present invention, the master disc of the optical recording medium having the track pitch of 1 / n of the spot size of the reproducing laser beam on the recording surface is obtained. In the data recording method for an optical recording medium, wherein pit information is recorded on each track of the master by using a laser beam for recording while rotating the master, while the master is rotated once, , The recording laser beam 1 in the radial direction of the master.
At the same time as the track pitch is displaced, while the master disk makes one rotation, the recording laser beam is reciprocally scanned by (n-1) track pitches in the radial direction of the master disk to record the pit information on the master disk. Since it was done, EX-R
When manufacturing a master of an optical recording medium having a track pitch of 1 / n of the spot size of a laser beam for reproduction such as OM, one beam is used for n beams.
It is possible to form pit information with high accuracy along a spiral locus forming a set, and further, it is possible to realize cost reduction for laser cutting.

According to another embodiment of the data recording apparatus for an optical recording medium, a master of the optical recording medium having a track pitch of 1 / n of the spot size of the reproducing laser beam on the recording surface is produced. In a data recording device of an optical recording medium for recording pit information on each track of the master by using a laser beam for recording while rotating the master, while the master is rotated once, Moving means for displacing the laser beam of the above-mentioned laser beam in the radial direction of the master by one track pitch, and simultaneously with the displacement operation of the recording laser beam by this moving means, while the master is making one revolution, the recording laser is moved. Since an optical deflector for reciprocally scanning the beam in the radial direction of the master by (n-1) track pitches is provided, the EX-ROM is provided.
For example, in the case of manufacturing a master of an optical recording medium having a track pitch of 1 / n of the spot size of the reproducing laser beam, one beam follows a spiral locus of one set of n. The pit information can be formed with high precision, and the cost for laser cutting can be reduced.

[Brief description of drawings]

FIG. 1 is an embodiment of a laser cutting device for realizing a data recording method for an optical recording medium according to the present invention (hereinafter, simply referred to as a laser cutting device according to the embodiment).
3 is a block diagram showing the configuration of FIG.

FIG. 2 shows an example of the displacement state of the irradiation position of the recording laser beam by the slide motor and the AOD of the laser cutting apparatus according to the present embodiment, where the horizontal axis indicates the elapsed time from the start of the constant speed rotation of the glass substrate ( The numbers on the horizontal axis indicate the number of rotations of the glass substrate) and the vertical axis indicates the number of track pitches, which are shown in the form of a graph. The figure (a) shows the laser beam for recording only by the movement operation by the slide motor. Shows the displacement of the irradiation position of the recording laser beam only by the optical deflection of the AOD, and the same figure (c) shows the combination of the movement operation by the slide motor and the optical deflection by the AOD. The displacement of the irradiation position of the recording laser beam in the case of being shown is shown.

FIG. 3 is an explanatory diagram showing an irradiation locus (spiral locus) of a recording laser beam by a slide motor and an AOD of the laser cutting apparatus according to the present embodiment.

FIG. 4 shows another example of the displacement state of the irradiation position of the recording laser beam by the slide motor and the AOD of the laser cutting apparatus according to the present embodiment, in which the horizontal axis indicates the elapsed time from the start of constant speed rotation of the glass substrate. (A number on the horizontal axis indicates the number of rotations of the glass substrate), and the vertical axis indicates the track pitch number, which is shown in the form of a graph. FIG. The displacement of the irradiation position of the beam is shown in FIG.
The displacement of the irradiation position of the recording laser beam when the optical deflection by OD is combined is shown.

FIG. 5 is a diagram showing a main part of a sample servo type optical disc on which data is recorded by the laser cutting apparatus according to the present embodiment, particularly a data part thereof, FIG.
Is a schematic diagram showing an example of a recording format in the data part, FIG. 7B is a table diagram showing the type of data to be recorded,
6C is a table showing the diffraction level of recorded data, FIG. 7D is a waveform diagram showing an RF signal waveform obtained by reproducing the data section, and FIG. 7E is the data section. FIG. 7 is a waveform diagram showing a push-pull signal waveform obtained by reproducing

6A and 6B are diagrams showing a specific example of a main part of the optical disc, in particular, a data part thereof. FIG. 6A is a schematic diagram showing an example of a recording format in the data part, and FIG. FIG. 3C is a table showing the type of data, and FIG. 6C is a table showing the data after the data to be recorded is converted into 16 levels.

FIG. 7 is a schematic diagram showing a recording format of a main part of the optical disc, particularly a servo part and a peripheral part thereof.

FIG. 8 is a block diagram showing a configuration of a reproducing apparatus that reproduces data from the optical disc, in particular, its reproducing system.

FIG. 9 is a block diagram showing a configuration of an arithmetic circuit and a signal discriminating circuit relating to signal processing of the reproduction system.

FIG. 10 is an explanatory diagram of a diffraction level by a non-wobble pit, a wobble pit, and a mirror surface recorded on the optical disc.

FIG. 11 is a characteristic diagram showing a level change with respect to a change in a reproduction laser beam position of an RF signal and a push-pull signal obtained by reproducing data in the reproduction system, and FIG. 11A is a level of the RF signal. The change is shown in FIG. 9B, which shows the change in the level of the push-pull signal.

FIG. 12 is a diagram for explaining changes in the reproduction laser beam position.

FIG. 13 is an explanatory diagram showing an information map used for 16-value discrimination in the signal discrimination circuit in the reproduction system.

FIG. 14 is a circuit diagram showing a configuration of a tracking error signal generation circuit incorporated in the arithmetic circuit.

FIG. 15 is a timing chart showing a tracking error signal generation operation in the tracking error signal generation circuit.

FIG. 16 is a schematic diagram showing a recording format of a servo unit that enables detrack tracking using the reference information of the optical disc.

FIG. 17 is a schematic diagram showing a recording format of an optical disc according to a conventional example.

FIG. 18 is an explanatory view showing irradiation loci of the two laser beams in the case where two laser beams spatially separated from each other are simultaneously irradiated to form a resist latent image of pit information on the glass substrate. is there.

[Explanation of symbols]

 1 Optical Disc 11 Pit 40 Optical Section 41 Glass Substrate 42 Laser Light Source 43A AOM 43B AOD 44 Prism 45 Objective Lens 50 Drive Section 51 Motor 52 FG Generation Circuit 53 Slide Motor 54 Servo Controller 60 Signal Processing Section 61 Formatting Circuit 62 Logical Operation Circuit 63A Modulation Ultrasonic generator 63B Deflection ultrasonic generator 64 Clock generator 65 System controller 66 Synthesis circuit

Claims (6)

[Claims] 1. A method for producing a master of an optical recording medium having a track pitch of 1 / n of a spot size of a laser beam for reproduction on a recording surface, wherein each track of the master is rotated while rotating the master. In a data recording method of an optical recording medium for recording pit information using a recording laser beam, the recording laser beam is displaced by one track pitch in a radial direction of the master while the master rotates once. At the same time, the pit information is recorded on the master by reciprocally scanning the laser beam for recording by (n-1) track pitches in the radial direction of the master while the master rotates once. Data recording method for optical recording medium. 2. The backward scanning of the recording laser beam is performed by at least one of positions corresponding to a plurality of mirror portions formed only on the mirror surface formed on the optical recording medium in the master. The method for recording data on an optical recording medium according to claim 1, wherein the recording is performed at a position corresponding to one mirror section. 3. The scanning of the recording laser beam in the backward direction is performed from the starting position where the recording laser beam is positioned every time the master rotates once, from the position corresponding to 1 byte in the track direction. The data recording method for an optical recording medium according to claim 1, wherein: 4. When the recording laser beam is reciprocally scanned in the radial direction of the master by (n-1) track pitches, at the same time, the recording laser beam is slightly deflected in accordance with wobbled pit information. Claim 1 characterized by the above-mentioned.
4. A data recording method for an optical recording medium according to any one of 3 to 3. 5. A method for producing a master of an optical recording medium having a track pitch of 1 / n of a spot size of a reproducing laser beam on a recording surface, wherein each track of the master is rotated while rotating the master. In a data recording device of an optical recording medium for recording pit information by using a recording laser beam, the recording laser beam is displaced by one track pitch in the radial direction of the master while the master rotates once. Simultaneously with the moving means and the displacement operation of the recording laser beam by the moving means, while the master disk makes one rotation, the recording laser beam is distributed in the radial direction of the master disk by (n-1) track pitch. A data recording device for an optical recording medium, comprising: an optical deflecting means for reciprocating scanning. 6. The optical deflecting means reciprocally scans the recording laser beam by (n−1) track pitches in the radial direction of the master while the recording laser beam is recorded according to wobbled pit information. 6. The data recording device for an optical recording medium according to claim 5, wherein the data recording device is slightly deflected.