JPH10199044A - Disk-like recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk-like recording medium capable of stably performing recording/reproducing operation even when the track pitch of a recording medium is made narrowed, and its production method. SOLUTION: Since respective servo pits Pt1 (Pt2 ) in a servo area on a disk are formed so as to be shared between adjacent tracks, and the pit width PtW of the servo pit Pt1 (Pt2 ) in the radial direction of the disk is formed so as to become wider than a regular pit width, a sufficient tracking modulation degree is secured, and the amplitude having grade capable of generating a servo clock is obtained even when a laser beam of a recording/reproducing device passes through the position being the most away from the servo pit Pt1 (Pt2 ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk-shaped recording medium capable of stably recording and reproducing various data including, for example, data for a computer, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Various data (application programs, file data, management data, etc.) used in computer equipment are provided by using recording media such as optical disks, magneto-optical disks, magnetic disks, memory cards, and magnetic tapes. It has become common for a user to arbitrarily store various data using these recording media.

[0003] Such recording media include a read-only ROM disk, a recordable RAM disk, a read-only ROM area, and a recordable / reproducible rewritable area (R).
There is a partial ROM disk or the like having an AM area. Among these recording media, for example, in a recording medium employing a sample servo method, a servo area is provided at the head of each area (segment) formed on the disk. Is provided.

In this servo area, a pit row having a predetermined pattern for expressing tracking servo information, information for generating a servo clock, and segment type information is formed (hereinafter referred to as a servo area in this specification). The pits formed inside are called servo pits).

FIG. 9 shows an example of a conventional servo pit formed on a recording medium. As shown in FIG. 9, the conventional servo pit Pt is formed at a position displaced (wobbled) by about 1/4 track pitch TP1 from the track center indicated by the broken line toward the inner circumference or the outer circumference of the disk. I have. That is, for example, in the servo pit Pt is in position PS _A, is formed at a position inner periphery side by about 1/4 track pitch TP1 wobble disk with respect to the track center, in the servo pits Pt in position PS _B, trucks Approximately 1/4 track pitch TP on the outer circumference of the disc relative to the center
It is formed at a position deviated by one. The track pitch size TP1 is, for example, 1.2 μm.

Then, a laser spot LSP is irradiated from the tracking servo system to the recording surface of the disk on which such servo pits Pt are formed, and a servo clock or tracking is performed based on the amount of reflected light reflected on the recording surface. An error signal or the like is generated.

FIG. 11 is a diagram schematically showing the conventional servo pit Pt shown in FIG. 9, and FIG. 12 is a diagram showing the conventional servo pit Pt shown in FIG. It shows a waveform of a reproduced pit signal obtained when the position indicated by the arrow is moved.

When the position shown by the arrow in FIG. 11 is moved in the positive direction of the X axis while irradiating the laser spot LSP to the disk from the tracking servo system, the tracking servo system reproduces the data as shown in FIG. A pit signal (hereinafter simply referred to as "pit signal") is obtained. That is, as shown by the arrow, the laser spot LSP moves from the track center to a position detracked by about 0.3 μm in the positive direction of the X-axis, so that
SP is when passing through farthest position (X-axis direction to 0.83μm approximately moved position) from the servo pits Pt _10, a relatively small pit signal P1 of the amplitude can be obtained. On the other hand, when the laser spot LSP passes directly over the servo pits Pt ₁₁ (X-axis direction to 2.91μm moved position), the smallest pit signal P2 amplitude is obtained.

That is, the amplitude of the pit signal obtained by the tracking servo system based on the pit signal value "1" becomes relatively small when the laser spot LSP passes through the position farthest from the servo pit Pt. When the laser spot LSP passes right above the servo pit Pt, it becomes largest, and this level difference becomes tracking information by the servo pit.

In the tracking servo system, the difference between the amplitudes of the pit signals P1 and P2 is detected as a tracking modulation degree, and a tracking error signal is generated based on the tracking modulation degree. In the decoding system, the pit signals P1, P2 are generated. A servo clock is generated based on

Since the pit signals P1 and P2 are used not only for the tracking servo but also for the reproduction clock extraction, the servo pits Pt formed in the servo area of the optical disk are used.
Indicates that the laser spot LSP is in a detrack state,
A pit signal P1 having a certain amplitude is provided so that the pit signal P1 having a certain amplitude can be obtained even when passing through a position farthest from a certain servo pit Pt. It is arranged to secure enough.

[0012]

By the way, in the above-mentioned recording medium, large capacity is always required, and therefore, high density recording of data is required. For example, when considering an optical disk, it is required to narrow a track pitch.

FIG. 10 is a diagram showing a conventional arrangement of servo pits formed on an optical disk capable of high-density recording by narrowing a track pitch. The track pitch TP2 of the optical disk in this example is, for example, 0.85 μm.
m.

The servo pit Pt shown in FIG.
The servo pits Pt having the same shape as the servo pits Pt shown in FIG. 9 are formed in the same arrangement. That is, the servo pits Pt is in position PS _A, is formed on the outer peripheral side of the disc with respect to the track center, the servo pits in the position PS _B Pt
Is formed on the inner peripheral side of the disc with respect to the track center.

However, in this case, the track pitch TP
2 is smaller than the track pitch TP1 of the optical disk shown in FIG. 9, the amount of deviation of the servo pits Pt is accordingly reduced. For this reason, when the laser spot LSP emitted from the tracking servo system detracks and passes through the position farthest from the servo pit Pt, the amount of light reflected on the recording surface increases, and the pit signal obtained by the tracking servo system is increased. Becomes large.

As a result, the waveform of the pit signal detected by the tracking servo system is shown by a solid line A in FIG. 14, and the tracking modulation degree, which is the amplitude difference between the pit signals P2 and P3, is shown in FIG. Track pitch TP1
Therefore, there is a problem that the tracking servo system cannot generate an accurate tracking error signal.

Therefore, as shown in FIG. 10B, for example, servo pits Pt are formed at positions deviated by 1/2 track pitch TP2 so that the servo pits Pt can be used mutually in adjacent tracks. It is conceivable to increase the amount of deviation from the servo pit Pt to the servo pit Pt. That is, the position PS _A to form a servo pits Pt servo pit Pt and the same shape as shown in FIG. 9 substantially in the center between the track center A, B shown by the broken line. Also, a servo pit Pt is formed at the position PS _B on the outer peripheral side of the disk with respect to the track center A,
For the track center B, a servo pit Pt is formed on the inner peripheral side of the disk.

When the servo pits Pt are formed in this manner, the amount of deviation from the track center to the servo pits Pt can be increased. For example, the laser spot LSP irradiated from the tracking servo system to the disk is detracked. When the position indicated by the arrow in FIG. 13 is moved in the positive direction of the X-axis, the pit signal indicated by the broken line B in FIG. 14 is obtained in the tracking servo system. That is, the laser spot LSP
A pit signal P5 is obtained when passes through the position farthest from the servo pit Pt, and a pit signal P6 is obtained when the laser spot LSP passes directly above the servo pit Pt.

When the servo pits Pt are formed as described above, as can be seen from FIG. 14, in the tracking servo system,
A sufficient tracking modulation degree can be obtained. However, when the laser spot LSP passes through the position farthest from the servo pit Pt, the amplitude of the pit signal P5 becomes very small, and a problem arises that a servo clock cannot be generated.

For this reason, in the recording medium of the conventional sample servo system, when the track pitch is narrowed,
It has been very difficult to perform a stable recording / reproducing operation.

[0021]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a recording / reproducing operation can be stably performed even when a track pitch of a recording medium is narrowed. An object of the present invention is to provide a disk-shaped recording medium and a method for manufacturing the same.

In order to achieve the above object, the disk-shaped recording medium of the present invention has a servo area in which a pair of servo pits displaced on both sides from a tracking center are formed to obtain at least servo information and clock information. Each servo pit in this servo area is formed so as to be shared between adjacent tracks, and the pit width of the servo pit in the disk radial direction is formed to be wider than a normal pit width. . Further, the pit width of the servo pit is formed to be wider by overlapping a plurality of pits having a normal pit width.

Further, the method of manufacturing a recording medium according to the present invention has a servo area in which a pair of servo pits displaced on both sides from a tracking center are formed in order to obtain at least servo information and clock information. In which the servo pits are formed so as to be shared by adjacent tracks, and the pit width of the servo pits in the radial direction of the disk is formed to be wider than the normal pit width. During the cutting operation of the servo pit, the output of the laser power for cutting is increased so that the pit width of the servo pit is made wider than the normal pit width.

Further, at the time of the servo pit cutting operation, the pit width of the servo pit is made wider than the normal pit width by displacing the cutting laser at a high frequency in the disk radial direction at the servo pit cutting timing. . Furthermore, during the servo pit cutting operation, one servo pit is formed by a plurality of pit forming operations deviated in the disk radial direction so that the pit width of the servo pit becomes wider than the normal pit width. To be formed.

According to the disk-shaped recording medium of the present invention, the servo pits in the servo area are formed so as to be shared between adjacent tracks, and the pit width of the servo pits in the disk radial direction is set. Since it is formed so as to be wider than the normal pit width, a sufficient tracking modulation degree can be ensured, and even when the laser beam detracks and passes through the position farthest from the servo pit, a certain degree is maintained. A pit signal having an amplitude can be obtained.

According to the recording medium manufacturing method of the present invention, the output of the cutting laser power is increased during the servo pit cutting operation, or the cutting laser is directed in the disk radial direction at the servo pit cutting timing. By displacing at high frequency, the pit width of the servo pit can be easily formed to be wider than the normal pit width. Furthermore, by forming one servo pit by a plurality of pit forming operations in which each servo pit is deviated in the disk radial direction, the pit width can be formed to be wider than the normal pit width.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a disk-shaped recording medium and a method of manufacturing the same according to the present invention will be described in the following order. Note that the object to be manufactured of the cutting device to which the present invention described in the present embodiment is applied is a partial ROM disk. [I disk format] <I-1. Track / Frame / Segment Structure><I-2. Structure of Servo Pit> [II Recording / Reproducing Device] <II-1. Apparatus Configuration and Operation> [III Cutting Apparatus] <III-1. Device Configuration><III-2. Servo pit cutting operation example>

[I Disk Format] <I-1. Structure of Track / Frame / Segment> First, the structure of the optical disk of this embodiment will be described. The optical disk of this example is an optical disk of a zone CAV system and of a sample servo system.

FIG. 1 shows tracks, frames,
It is the figure which showed the structure of the segment typically in the circumferential direction. One track of the optical disk of this example shown in FIG.
Nine 100 frames are formed, and one frame is formed with a unit area of 14 segments. Therefore, one track is composed of 1400 segments.

FIG. 1 shows that one round of the track on the optical disk is one.
400 segments (segments SEG0 to SEG1
399). Also one
Four segments (for example, segments SEG0 to SEG
13) also shows that one frame is formed.

The segments SEG0 to SEG1399 are
Address segment ASEG0 as its content type
~ ASEG99 and data segment DSEG0 ~ DSE
G1299.

In the address segment ASEG, position information in the radial direction (ie, track number) and position information in the tangential direction (ie, segment number) on the disk are recorded in advance by emboss pits. The address segment ASEG exists every 14 segments. That is, one exists in one frame. Therefore, there are 100 address segments ASEG0 to ASEG99 in one track. The address segments ASEG0 to ASEG99 are the leading segments of the frames 0 to 99, respectively.

There are 13 segments between one address section ASEG and the next address segment ASEG, and each of the 13 segments is a data segment DSEG. That is, for one frame, for example, data segments DSEG0 to DSEG
12, there are 13 data segments DSEG, and 1 track has 1300 data segments (D
SEG0 to DSEG1299).

Each segment (SEG0 to SEG1)
399) are formed in an area for 216 servo clocks with respect to the servo clock SCK. An area for 24 servo clocks is set as a servo area ARs, and an area for 192 servo clocks is set as a data area ARd.

The data in the address segment ASEG is recorded on the disk in advance by embossing pits or the like. Data segment DSEG also
Same length as address segment ASEG (216SC
Similarly, a servo area (24SCK) in which servo pits described later are formed by embossing or the like is arranged at the beginning of the segment.

<1-2. Structure of Servo Pit> Next, the structure of the servo pit formed in the servo area ARs of the optical disk as described above will be described. FIG. 2 is an enlarged view showing servo pits formed in the servo area ARs of the optical disc of the present embodiment. Note that FIG.
(A), track pitch TP of the optical disc shown in (b)
2. For example, 0.85 μm which enables high-density recording of data
It has been.

The servo pit Pt ₁ shown in FIG.
Servo pits Pt ₁ formed on adjacent tracks are arranged so as to be commonly used for each track. For example, servo pits Pt _{1 at} position PS _A are:
It is formed substantially at the center between the track centers A and B shown by the broken lines. Also, the servo pit Pt of the position PS _B
1 is formed on the outer peripheral side of the disk with respect to the track center A and on the inner peripheral side of the disk with respect to the track center B. In other words, every other servo pit is formed at the position where the servo pits Pt ₁ of a plurality of tracks provided in the servo area are formed. Furthermore, the pit width Pt _w of these servo pits P ₁ are formed so as to be larger than the pit width of a conventional servo pits Pt shown in FIG. Although not shown, a normal data pit such as RO
The pits are wider than the pits of the pits forming the M data and the address data.

The servo pit Pt shown in FIG.
₂ are arranged so that the servo pits Pt ₂ formed on adjacent tracks can be commonly used for each track, and _two pits Pt ₂ having the same shape as the conventional servo pit Pt shown in FIG. and some are formed so as to overlap the are formed such that the servo pits Pt ₁ and the same pit width Pt _W shown in FIG. 2 (a).

The servo pit P shown in FIG.
At t ₂ , two pits P of normal pit size
By forming such that a portion of the t overlap, but the pit width Pt _W is formed to have a wider pit width Pt by further overlapping a plurality of pits Pt
It is also possible to form _W to be wide.

[II Recording / Reproducing Apparatus] <II-1. Apparatus Configuration and Operation> Next, a recording / reproducing apparatus for performing a recording / reproducing operation on the optical disk on which servo pits are formed according to the present embodiment as described above will be described with reference to the block diagram of FIG.

The optical disk 1 is, for example, a ROM disk,
It is a RAM disk or a partial ROM disk. The optical disk 1 is rotationally driven at a predetermined rotational speed for each zone by a spindle motor 2. The rotation speed servo control of the spindle motor 2 is performed by the spindle control unit 3. For example, the spindle control unit 3 detects the rotation speed of the spindle motor 2 based on an FG pulse (frequency signal synchronized with the rotation speed) from the spindle motor 2, and supplies reference speed information SK for each zone from the controller 6, By comparing the speed information SK with the rotation speed of the spindle motor 2 and performing acceleration / deceleration of the spindle motor 2 based on the error information, a disk rotation operation at a required rotation speed is realized.

For the optical disc 1 being rotated,
Laser light from the optical pickup 4 is irradiated. The optical pickup 4 includes, for example, a laser light source 4c such as a laser diode or a laser coupler, an optical system 4e such as various lenses or a beam splitter, an objective lens 4a serving as an output end of a laser beam, and a detector 4d detecting reflected light from a disk. And a biaxial mechanism 4b for holding the objective lens 4a movably in the tracking direction and the focus direction. On / off of the laser output from the laser light source 4c and the output level in the optical pickup 4 are controlled by the laser control unit 5.

The recording / reproducing apparatus is connected to the host computer 90 by the interface unit 19, and the recording / reproducing operation of the data is executed by the controller 6 receiving the recording request and the reproducing request from the host computer 90. Will be.

At the time of recording, from the host computer 90,
Data to be recorded is supplied together with the recording request. The recording data D _REC is supplied from the interface unit 19 to the encoder 25, where necessary encoding processing is performed.

When the disk 1 is a RAM disk or a partial ROM disk, data can be magneto-optically recorded in the rewritable area.
Recording methods are roughly classified into an optical modulation method and a magnetic field modulation method.

In the light modulation method, an external magnetic field is applied in a fixed direction perpendicular to the disk recording surface,
This method modulates laser light with recording data. That is, when this method is adopted, at the time of recording, the controller 6 causes the magnetic head driver 26 to apply an external magnetic field of N or S from the magnetic head 27 to the disk recording surface.
Then, the recording data encoded by the encoder 25 is supplied to the laser control unit 5, and the laser control unit 5 turns on / off the laser output from the laser light source 4c according to the recording data. As a result, the portion irradiated with the laser has the polarity of the external magnetic field, and the recording data is recorded on the disk 1 as magnetic field information.

On the other hand, the magnetic field modulation method is a simple magnetic field modulation method in which a magnetic field modulated based on recording data is applied to a disk recording surface and a laser beam is continuously irradiated with a constant light amount. There is a laser strobe magnetic field modulation method in which a magnetic field modulated based on recording data is applied to a surface and a laser beam is pulsed.

When these magnetic field modulation methods are employed, during recording, the controller 6 controls the laser control unit 5 so that the laser output from the laser light source 4c is continuously emitted or pulsed. The recording data encoded by the encoder 25 is supplied to a magnetic head driver 26, and the magnetic head driver 26
Applies an N or S magnetic field from the magnetic head 27 according to the recording data. As a result, the recording data is recorded on the disk 1 as magnetic field information.

The data reading position of the optical pickup 4 can be moved in the radial direction. Although not specifically shown, a sled mechanism is provided to allow the entire optical pickup 4 to move in the radial direction of the disc, thereby performing a large movement of the reading position, and moving the objective lens 4a to the biaxial mechanism 4b. Is moved in the radial direction of the disk, that is, the reading position is moved slightly by the tracking servo operation.

Instead of the sled mechanism for moving the optical pickup 4, a mechanism for sliding the disk 1 together with the spindle motor 2 may be provided. In addition, the objective lens 4a is moved by the biaxial mechanism 4b in a direction in which the objective lens 4a comes into contact with and separates from the disk 1, so that the laser spot L
SP focus control is performed.

When the disk 1 is loaded by a loading mechanism (not shown), the rotation drive by the spindle motor 2 is started. When the disk 1 reaches a predetermined rotation speed, the reading position is controlled so that the optical pickup 4 reads data in the GCP zone formed on the inner or outer peripheral side of the disk 1. This GCP
In the zone, necessary start-up processing such as focusing is performed, and then a recording or reproducing operation according to a request from the host computer 90 is started.

As the detector 4d of the optical pickup 4, for example, a four-segment detector having a four-segment light receiving area, or magnetic field data (M
O data) is detected for each polarization component by the magnetic Kerr effect, and a detector or the like for obtaining an RF signal as MO data is provided.

From each light receiving area of the detector 4d,
A current signal S1 corresponding to the amount of received light is output, and these are supplied to the I / V conversion matrix amplifier 7. The I / V conversion matrix amplifier 7 performs current-voltage conversion on the received light amount signal S1, and generates necessary signals such as an RF signal, a push-pull signal, and a focus error signal FE by performing arithmetic processing on signals from the respective light receiving regions. I do.

A focus error signal FE serving as focus state error information is supplied to the servo controller 8. The servo controller 8 is equipped with a focus phase compensation circuit, a focus driver, and the like as a processing unit of a focus system, and generates a focus drive signal based on the focus error signal FE and applies the signal to the focus coil of the two-axis mechanism 4b. As a result, a focus servo system for converging the objective lens 4a to the just focus point is formed.

From the I / V conversion matrix amplifier 7, an RF signal used for generating the servo clock SCK and the data clock DCK is output as a signal S2. The signal S2 is obtained by removing the low frequency fluctuation of the RF signal by the clamp circuit 9 and digitizing the signal S by the A / D converter 10.
It becomes 3. This signal S3 is supplied to the controller 6, the PLL circuit 11, and the tracking error generator 16.

The PLL circuit 11 generates the servo clock SCK synchronized with the RF signal by controlling the oscillation frequency of the internal oscillator based on the phase error between the signal S3 and the oscillation output and performing a predetermined frequency dividing process. This servo clock SCK is used as a sampling clock in the A / D converter 10 and is supplied to the timing controller 17. In the PLL circuit 11, the data clock DCK is generated by dividing the frequency of the servo clock SCK.
4. It is supplied to the laser control unit 5.

The timing controller 17 generates a necessary timing signal for each section based on the servo clock SCK and the data clock DCK. For example, a sampling timing Ps for extracting a servo pit for a three-phase tracking operation, a synchronization timing DSY for a decoding operation in the data detection unit 14, and the like are generated.

The tracking error signal T by the so-called three-phase tracking control is generated by the PLL circuit 11, the timing controller 17, and the tracking error generator 16.
E is generated and supplied to the servo controller 8. However, the controller 6 controls the tracking error generator 16 and the servo controller 8 to perform polarity switching control for the tracking error signal TE, switching control using a servo pit pattern, and the like, thereby realizing necessary scanning. Also, detrack tracking can be executed by, for example, giving an offset to the tracking error signal TE. For example, a scan that passes just above one servo pit track can be executed.

From the I / V conversion matrix amplifier 7, an RF signal and a push-pull signal used for data extraction are output as a signal S4. This signal S4 becomes a signal S5 digitized by the A / D converter 13 after the low frequency fluctuation of the RF signal is removed by the clamp circuit 12.

This signal S5 is supplied to a data detector (ie, a decoder) 14. In the data detector 14, the timing controller 17 performs data decoding processing based on the synchronization timing DSY generated based on the data clock DCK, and obtains reproduction data D _PB . For example, a waveform equalization process, a demodulation process for a modulation process adopted as a recording format, an error correction process, and the like are performed, and the data is encoded as reproduction data D _PB . This reproduced data D
_{The PB} is supplied to the host computer 90 via the interface unit 19.

When recording / reproducing the various types of discs described above in the recording / reproducing apparatus configured as described above, the laser beam emitted from the optical pickup 4 depends on the amount of light received when passing through the servo area ARs of the optical disc 1. The obtained current signal S1 is obtained as a pit signal, and the servo clock SCK and the tracking error signal TE are generated based on the pit signal.

FIG. 4 schematically shows the structure of servo pits formed in the servo area ARs of the optical disk of this embodiment shown in FIG. 2, and FIG. 4 (a) shows the structure of FIG. 2 (a). servo pits Pt ₁ shown, FIG. 4 (b) are shown respectively of the servo pits Pt ₂ shown in FIG. 2 (b).

When the optical pickup 4 of the recording / reproducing apparatus shown in FIG. 3 passes through the position indicated by the arrow in FIGS. 4A and 4B while irradiating the laser light, the optical pickup 4 The pit signal shown by the solid line in FIG. 5 (a) was obtained. That is, while irradiating a laser beam from the optical pickup 4, a distance of about 0.4 μm
By moving the detracked position in the positive direction of the X axis, the amplitude is relatively small when the laser beam passes through a position farthest from the servo pit Pt (a position moved by about 0.83 μm in the X axis direction). A pit signal P1 was obtained, and it was found that a pit signal P2 having the largest amplitude was obtained when the laser beam passed directly above the servo pit Pt (a position shifted by 2.91 μm in the X-axis direction).

From this result, when the track pitch of the optical disk was narrowed, the servo pits P as shown in FIG.
t ₁ (or Pt ₂ ) are arranged so that they can be commonly used in adjacent tracks, and the servo pit P
By forming the pit width Pt _{W of} t ₁ (or Pt ₂ ) to be wider than the normal pit width, FIG.
As shown by the dashed line in (a), it has been found that the amplitude of the pit signal can be obtained even when the laser beam, from which a pit signal could hardly be obtained conventionally, passes through the position farthest from the servo pit Pt. Therefore, an accurate servo clock can be generated in the recording / reproducing apparatus.

FIG. 5B is a diagram showing the relationship between the detrack amount of the optical pickup 4 and the degree of tracking modulation. From this result, when servo pits of the optical disk are formed as in this example, It was found that even when the detrack amount was changed, a tracking modulation degree almost the same as that of the related art was secured. Therefore, an accurate tracking error signal can be generated in the recording / reproducing apparatus.

Next, a cutting apparatus and a cutting method for forming the servo pits Pt ₁ (or Pt ₂ ) of the disk recording medium of the present invention as described above will be described. [III cutting device] <III-1. Device Configuration>

For example, the manufacturing process of a partial ROM disk can be roughly divided into a so-called mastering process (mastering process) and a disc forming process (replication process). The mastering process is a process up to completion of a metal master (stamper) used in the disc making process, and the disc making process is a process of mass-producing an optical disc, which is a duplicate of the stamper, using the stamper.

More specifically, in the mastering step, so-called cutting is performed in which a photoresist is applied to a polished glass substrate, and pits Pt are formed on the photosensitive film by exposure to a laser beam. The information as the pit Pt to be recorded includes pit data in a ROM area, address data in an address segment,
Further, it is a servo pit in the servo area ARs.

The pit data and the like in the ROM area are prepared in a preparation process called premastering. When the cutting is completed, after performing a predetermined process such as development, the information is transferred onto the metal surface by, for example, electroforming, and a stamper necessary for duplicating the disc is created.

Next, by using this stamper, information is transferred onto a resin substrate by, for example, an injection method and the like, a reflective film is formed thereon, and processing such as processing into a required disk form is performed. Complete the final product.

As shown in FIG. 6, for example, the cutting apparatus includes an optical unit 40 for irradiating a photoresist glass substrate 41 with a cutting laser beam to perform cutting, and a driving unit 50 for driving the glass substrate 41 to rotate.
And a signal processing unit 60 that converts the input data into recording data and controls the optical unit 40 and the driving unit 50.

The optical section 40 includes a laser light source 42 made of, for example, a He-Cd laser, and an acousto-optic light modulator 43A for modulating (on / off) the light emitted from the laser light source 42 based on the recording data. (AOM), an acousto-optic light deflector 43B (AOD) for deflecting the light emitted from the laser light source 42 based on the recording data, and a prism 44 for bending the optical axis of the modulated beam from the light deflector 43B.
And an objective lens 4 for condensing the modulated beam reflected by the prism 44 and irradiating the photoresist surface of the glass substrate 41 with the modulated beam.
5 are provided.

The driving unit 50 includes a motor 51 for driving the glass substrate 41 to rotate, an FG 52 for generating an FG pulse for detecting the rotation speed of the motor 51, and a glass substrate 4.
1 comprises a slide motor 53 for sliding the slider 1 in its radial direction, and a servo controller 54 for controlling the rotation speed of the motor 51, the slide motor 53, the tracking of the objective lens 45 and the like.

The signal processing section 60 further comprises a formatting circuit 61 for forming input data by adding, for example, an error correction code to the source data from the computer.
A logical operation circuit 62 for performing predetermined arithmetic processing on input data from the formatting circuit 61 to form recording data; and an optical modulator 43A and an optical deflector based on the recording data from the logical operation circuit 62. A driving circuit 63 for driving the driving circuit 43B, a clock generator 64 for supplying a clock to the logical operation circuit 62 and the like, a system controller 65 for controlling the servo controller 54 and the like based on the supplied clock, and a laser A laser driving circuit 66 for controlling the driving of the light source 42 is provided.

In this cutting apparatus, the servo controller 54 operates the motor 51 at the time of cutting.
Thus, the glass substrate 41 is driven to rotate at a predetermined constant angular velocity for each zone, and while the glass substrate 41 is being rotated by the slide motor 53, the glass substrate 41 is slid so as to form a spiral track at a predetermined track pitch. At the same time, the light emitted from the laser light source 42 is converted into a modulated beam based on the recording data via the optical modulator 43A and the optical deflector 43B, and is emitted from the objective lens 45 to the photoresist surface of the glass substrate 41. The photoresist is exposed based on the recorded data.

On the other hand, the input data to which the error correction code or the like has been added by the formatting circuit 61 is supplied to a logical operation circuit 62 to form recording data. The logical operation circuit 62 generates data to be recorded as the above-described two-channel twin pits, or generates data to be recorded as the logical twin pits.

The recording data is supplied to a drive circuit 63, which controls the optical modulator to be turned on at a bit timing at which a pit Pt is to be formed in accordance with the recording data. The optical modulator is controlled to be turned off at a bit timing and a period in which is not formed (that is, a mirror surface M and a land LD).

Further, the drive circuit 63 operates when the servo pit does not coincide with the tracking center at that time, that is, when a servo pit track which does not coincide with the groove track / land track in the rewritable area is formed. In order to form the servo pit at a position shifted in the radial direction from the tracking center, drive control is performed so that the deflection direction by the optical deflector becomes the + Δt direction or the −Δt direction at the servo pit timing.

When the expression using the wobble pits is performed in the ROM area as described above, the deflection direction by the optical deflector is set to the + Δt direction or the −Δt direction at the bit timing corresponding to the wobble pits. Control.

By such an operation, an exposure portion corresponding to the groove / servo pit / address information and the like is formed on the glass substrate 41 based on the format.
Exposure portions corresponding to pits as data in the OM area are formed. Thereafter, development, electroforming and the like are performed to produce a stamper, and a partial ROM disk is produced using the stamper.

<III-2. Example of Servo Pit Cutting Operation> An example of a servo pit cutting operation formed on an optical disk by the cutting apparatus as shown in FIG. 6 will be described with reference to FIGS.

FIG. 7 shows an example of a cutting operation when forming the servo pit Pt ₁ of the present example as shown in FIG. 2A. In this case, the deflection direction of the optical deflector 43B is changed to the + Δt direction or the −Δ
Drive control is performed in the t direction. The optical modulator 43a in the bit timing of forming the servo bits Pt ₁
Is turned on, and a high-frequency signal is applied to the optical deflector 43B. By performing such control, an exposed portion corresponding to the servo pit Pt ₁ having the increased pit width is formed on the glass substrate 41.

Note that, without applying a high-frequency signal to the optical deflector 43B, for example, by controlling the drive so that the output level of the laser light source 42 is increased by the laser drive circuit 46, the exposure portion corresponding to the servo pit Pt ₁ is controlled. Will be formed. Thereafter, a stamper is generated by performing development, electroforming, and the like, and a partial ROM disk is produced using the stamper.

FIG. 8 shows an example of a cutting operation when a servo pit Pt ₂ is formed by partially overlapping two pits Pt as shown in FIG. 2B. FIG. 8 (a), to form the servo pits Pt ₂ at a position shifted from the track center in the radial direction of the disk, the polarization direction by the optical deflector 43B at the timing of forming the servo pits Pt ₂ + Delta] t direction or -
Drive control is performed in the Δt direction, and the optical modulator 43A is controlled to be turned on at a bit timing at which a servo pit Pt ₂ is to be formed. By such a control operation, the glass substrate 4
Exposure portions corresponding to the two pits Pt to be servo pits Pt ₂ are formed on 1.

When the servo pits Pt ₂ are formed by the _two pits Pt as described above, for example, a laser light source 42, an optical modulator 43A, an optical deflection device constituting the optical section 40 of the cutting device shown in FIG. Device 43B, a prism 44, and another objective lens 45 are separately provided,
To form a position radially offset servo pits Pt ₂ from the track center as shown in FIG. 9, each of the optical deflector 43B, and the drive control so that the + Delta] t direction or -Δt direction the polarization direction of the 43B Keep it. Then, at the bit timing for forming the bit Pt, the optical deflectors 43B and 43B are further driven and controlled in the + and-directions, and the optical modulator 43A is controlled to the on state. By such a control operation, it is also possible to form an exposed portion on the glass substrate 41 corresponding to the two pits Pt to be the servo pits Pt ₂ .

[0086]

As described above, in the disk-shaped recording medium of the present invention, the servo pits in the servo area are formed so as to be shared between adjacent tracks, and the disk of the servo pits is formed. Since the pit width in the radial direction is formed to be wider than the normal pit width, a sufficient tracking modulation degree can be secured, an accurate tracking error signal can be generated, and the reproduction laser Even when the light passes through a position farthest from the servo pit, a pit signal having a certain amplitude can be obtained and a servo clock can be generated. Therefore, a disk-shaped recording medium capable of performing a stable recording / reproducing operation even when the track pitch is narrowed can be provided.

Further, according to the recording medium manufacturing method of the present invention, the laser power for cutting is increased during the cutting operation of the servo pit, or the laser for cutting is transmitted at a high frequency in the radial direction of the disk at the cutting timing of the servo pit. , The pit width can be easily formed to be wider than the normal pit width. Furthermore, when one servo pit is formed by a plurality of pit forming operations deviated in the disk radial direction, the power of the cutting laser is increased or the cutting laser is displaced at a high frequency. There is an advantage that the pit width can be made wider than the normal pit width without any problem.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a track / frame / segment image of a disk according to an embodiment of the present invention.

FIG. 2 is a diagram showing a shape of a servo pit in a servo area according to the embodiment.

FIG. 3 is a block diagram of a recording / reproducing device corresponding to the disk of the embodiment.

FIG. 4 is a diagram schematically showing a structure of a servo pit of the disk according to the embodiment;

FIG. 5 is a diagram showing pit signals obtained from servo pits of the disk according to the embodiment.

FIG. 6 is a block diagram of the disk cutting device according to the embodiment;

7 is a diagram illustrating a cutting operation example of the servo pits Pt ₁ disk embodiment.

FIG. 8 is a diagram showing an example of a cutting operation of a servo pit Pt ₂ of the disk of the embodiment.

FIG. 9 is a diagram showing a structure of a servo pit formed in a servo area of a conventional disk.

FIG. 10 is a diagram showing a structure of a servo pit formed in a servo area of a conventional disk capable of high-density recording.

11 is a diagram schematically showing the structure of the servo pit shown in FIG.

FIG. 12 is a diagram illustrating a waveform of a pit signal obtained from a servo pit when a laser spot passes through a position indicated by an arrow in FIG. 11;

FIG. 13 is a diagram schematically showing the structure of the servo pit shown in FIG. 10 (b).

14 is a diagram showing a waveform of a pit signal obtained from the servo pit when the laser spot detracks in the servo pit shown in FIG.

[Explanation of symbols]

1 disc, 2 spindle motor, 3 spindle controller, 4 optical pickup, 4a objective lens, 4
b 2 axis mechanism, 4c laser light source, 4d detector, 4
e Optical system, 5 Laser controller, 6 Controller, 7
I / V conversion matrix amplifier, 8 servo controller, 8a phase compensation circuit, 8b 2-axis driver, 9, 1
2 Clamp circuit, 10, 13 A / D converter, 11
PLL circuit, 14 data detector, 16 tracking error generator, 16a sample and hold circuit, 16b
Error signal generation circuit, 17 timing controller, 19 interface section, 25 encoder, 2
6 magnetic head driver, 27 magnetic head, 40 optical unit, 41 glass substrate, 42 laser light source, 43A optical modulator, 43B optical deflector, 44 prism, 45 objective lens, 50 drive unit, 51 motor, 52FG, 5
3 slide motor, 54 servo controller, 60
Signal processing unit, 61 formatting circuit, 62 logical operation circuit, 63 drive circuit, 65 system controller, LSP laser spot, Pt pit, Pt ₁ ,
Pt ₂ servo pit, ARs servo area, ARd
Data area

Claims (5)

[Claims] 1. A servo area having a pair of servo pits displaced on both sides from a tracking center to obtain at least servo information and clock information, wherein each servo pit in this servo area is shared between adjacent tracks. A disk-shaped recording medium characterized in that the servo pits are formed so that the pit width of the servo pits in the radial direction of the disk is wider than a normal pit width. 2. The disk-shaped recording medium according to claim 1, wherein the servo pits are made wider by overlapping a plurality of pits each having a normal pit width. 3. A servo area in which a pair of servo pits displaced on both sides from a tracking center to obtain at least servo information and clock information is formed, and each servo pit in this servo area is shared between adjacent tracks. The pit width in the disk radial direction of the servo pits is formed so as to be wider than the normal pit width. A method for manufacturing a disk-shaped recording medium, wherein the pit width of a servo pit is made wider than a normal pit width by increasing the output of a cutting laser. 4. A servo area in which a pair of servo pits displaced on both sides from a tracking center to obtain at least servo information and clock information is formed, and each servo pit in this servo area is shared between adjacent tracks. The pit width in the disk radial direction of the servo pits is formed so as to be wider than the normal pit width. A method for manufacturing a disk-shaped recording medium, wherein a pit width of a servo pit is made wider than a normal pit width by displacing a cutting laser at a high frequency in a disk radial direction at a servo pit cutting timing. 5. A servo area in which a pair of servo pits displaced on both sides from a tracking center to obtain at least servo information and clock information is formed, and each servo pit in this servo area is shared between adjacent tracks. The pit width in the disk radial direction of the servo pits is formed so as to be wider than the normal pit width. A disk wherein one servo pit is formed by forming a plurality of pits deviated in the radial direction of the disk, so that the pit width of the servo pit becomes wider than a normal pit width. Method for manufacturing a recording medium.