JPH02263326A - Servo pattern recording system for master disk of optical memory - Google Patents

Abstract

PURPOSE:To stably extract the clock signal even at the time of off-track when a servo pattern consisting of the wobbled pits and the clock pits is recorded on the master disk of an optical memory by making the length of the clock pit in the direction almost vertical to the track direction longer than the wobbled pit. CONSTITUTION:The wobbled pits are recorded by a 1st energy beam, and the clock pits are recorded by a 2nd energy beam having the size in the track width direction larger than that in the track direction. Otherwise the wobbled pits are recorded by a 1st energy beam and the clock pits are recorded by both 1st and 2nd energy beams which are set side by side in the direction almost vertical to the track direction. Then the length of the clock pit is made longer in the direction almost vertical to the track direction than that of the wobbled pit. Furthermore, the clock pits are continuously recorded with high density. Thus a stable clock signal can be extracted even at off-track.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention relates to a method for recording servo patterns on a master disk used for manufacturing optical memories such as optical disks, and particularly relates to a method for recording servo patterns on a master disc used for manufacturing optical memories such as optical disks, and in particular to a method for recording servo patterns on a master disk used for manufacturing optical memories such as optical disks. This invention relates to a method for recording servo patterns on an optical memory master.

(Prior Art) A sample servo format is known as one of the recording formats for optical discs. As shown in FIG. 12, concentric solid or spiral tracks on the optical disk 1 are divided into a servo area 2 and a data area 3, and a servo pattern as shown in FIG. 13 is created on the servo area 2. It is to be recorded.

This servo pattern is a first signal (hereinafter referred to as wobbled pit) 11 used for tracking control.
．． 12 and a second signal (
Wobbled pits 11 and 12 are distributed on both sides of the track, and are recorded, for example, at a position shifted by 1/4 track pitch from the track center line, and clock bit 13 is recorded on the track center line. ing.

Such optical discs are manufactured using master discs on which servo patterns are recorded in advance. Conventionally, when recording servo patterns on a master disc, a single laser beam was used.
By deflecting this by 1/4 track pitch using an AO modulator or EO modulator and irradiating it onto the master,
Wobbled pits are recorded, and clock bits are recorded by irradiating a laser beam without deflecting it.

However, in optical discs manufactured using master discs with servo patterns recorded in this way, when the reflected light from the clock bits is detected during playback and the clock signal is extracted, the laser beam irradiation position deviates from the track. Another problem is that during so-called off-track, the degree of modulation of the detection signal (amplitude of the detection signal) is significantly lower than when on-track. For example, NA-0.6, beam filling factor of laser beam 1.0, λ-830nm,
When a tarok pit with a track pitch of 1.5 μm, a depth of 1300 people, and a width of 0.6 μm is formed, the modulation degree of the detection signal from the clock bit is 8 when on track.
096, while it is 10% when off-track.

When the degree of modulation of the detection signal decreases to this extent, it becomes difficult to extract the clock signal. The reason why there is a difference in the degree of modulation of the detection signal between on-track and off-track is because there is a difference in the leakage m of reflected light from adjacent tracks.

(Problems to be Solved by the Invention) As described above, in the conventional optical memory master servo pattern recording technology, when reproducing signals from the optical memory, the degree of modulation of the detection signal from the clock bit decreases significantly in an off-track state. Therefore, there is a problem in that it becomes difficult to extract the clock signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a servo pattern recording method for an optical memory master, which can stably extract a tarlock signal even when off-track and can form a lock bit on an optical memory.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, wobbled pits are recorded with a first energy beam, and clock bits are recorded with a second energy beam whose dimension in the track width direction is larger than the dimension in the track direction. Record by beam. Alternatively, using first and second energy beams arranged substantially perpendicular to the track direction,
Wobbled pits are recorded with a first energy beam and clock bits are recorded with both the first and second energy beams.

As a result, the clock bits are recorded substantially perpendicularly to the track direction, longer than the wobbled pits, consecutively, or with high density.

(Function) If the clock bits are lengthened in a direction substantially perpendicular to the track direction, are made continuous, or are recorded at a high density on the optical memory master disc in this way, when reproducing signals from the optical memory, the on-track The difference in the amount of reflected light leaking from adjacent tracks between off-track and off-track is reduced, and the difference in the degree of modulation of detection signals is also reduced. This allows stable clock signal extraction even when off-track.

(Example) Below - a detailed description of the invention with reference to the drawings.

FIG. 1 shows a recording device for an optical disk master according to an embodiment of the present invention. In the figure, a laser light source 1 is, for example, an Ar+ laser, and a laser beam emitted from this laser light source 1 is transmitted to a half mirror 102 and a mirror 103.
It is divided into two by

The first laser beam includes a convex lens 104, an AO (acousto-optic) modulator 106, a slit plate 108, and a convex lens 110.
Similarly, the second laser beam is guided to a mirror 113 via a convex lens 105, an AO modulator 107, a slit plate 109, and a convex lens 111.

The first laser beam reflected by mirror 112 is
The light is deflected by the AO modulator 114, guided by a mirror 115, guided to convex lenses 116 and 117, and incident on the polarizing beam splitter 124.

On the other hand, the second laser beam reflected by the mirror 113 passes through a beam shaping system consisting of a mirror 118, a cylindrical lens 119, a convex lens 120, a slit plate 121, and a convex lens 122, and is further guided by a mirror 123 to a polarizing beam splitter 124. incident on .

The first and second laser beams guided onto the same optical path by the polarizing beam splitter 124 are guided by the mirror 125 and are guided by the objective lens 126 to the optical disk master 1.
27 and records the servo pattern.

The optical disk master 127 has, for example: ■ a resist layer formed directly or through an adhesive layer on a glass disk, or ■ a metal layer formed on a glass disk, and a resist layer directly or through an adhesive layer formed on the glass disk. A structure in which a resist layer is formed on a metal plate, either directly or through an adhesive layer,
Or (2) A metal layer is formed on a metal disk, and a resist layer is formed thereon either directly or through an adhesive layer.

FIG. 2 shows the first and second laser beams 21.2 that are focused and irradiated onto the optical disk master 127 using the configuration shown in FIG.
The first laser beam 21 is a circular beam, and the second laser beam 22 is long in the track direction (circumferential direction) and in a direction approximately perpendicular to direction 1 (disc radial direction). It is a shaped beam (hereinafter referred to as a horizontally long beam). And these laser beams 21
22 are arranged in the track direction.

The shape of the horizontally long beam such as the second laser beam 22 can be obtained by a beam shaping system consisting of a beam expander constituted by the cylindrical lens 119, convex lens 120, and convex lens 122, and the slit plate 121 in FIG. It will be done. Note that a pinhole plate may be used instead of the slit plate 121.

FIG. 3 shows a servo pattern recorded using the laser beams 21 and 22 having the beam shape and arrangement as shown in FIG. First, in FIG. 3(a), wobbled pits 31 and 32 are recorded by deflecting the first laser beam 21 to both sides of the track by the AO modulator 114, and second laser beams 31 and 32 are recorded on the center line of the track. A horizontally long clock pit 33 formed by the beam 22 is recorded.

In FIG. 3(b), wobbled pits 31 and 32 are similarly recorded, and clock pits 34 that are continuous in the radial direction of the disk are also recorded. To record such continuous clock pits 34, the width of the second laser beam 22 in the disk radial direction is set to such a size that the bit formed by the laser beam 22 overlaps the adjacent bit (for example, about 2 μm). All you have to do is choose.

In FIG. 3(e), wobbled pits 31 and 32 are recorded in the same way, and when recording clock pits, the track pitch is set to 1/2, and the first laser beam 21 is used to form the wobbled pits on the original track center line. The horizontally elongated clock bits 36 formed by the second laser beam 22 are recorded between the original tracks. That is, the intervals between the clock bits 35 and 36 in the disk radial direction are made small, and the clock bits are recorded at high density.

Next, another embodiment of the present invention will be described.

FIG. 4 shows another example of the beam shapes and arrangement of the first and second laser beams 41 and 42. Similarly to FIG. 2, the first laser beam 41 is a circular beam, and the second The laser beam 42 consists of a horizontally elongated beam that is elongated in the radial direction of the disk, and in this example, these laser beams 41 and 42 are aligned in the radial direction of the disk, that is, in a direction substantially perpendicular to the track direction.

FIG. 5 shows a servo pattern recorded using laser beams 41 and 42 having the beam shape and arrangement as shown in FIG. In Figure 5(a), Wobbled Pi) 51,5
2 is recorded by the first laser beam 41 as in the case of FIG. 3, and the clock bit is recorded by the first laser beam 41 on the original track center line as in the case of FIG. 3(C). A second laser beam 42 is inserted between the formed clock bits 53 and the original tracks.
The horizontally long clock bit 54 formed by the clock bit 54 is recorded simultaneously. As a result, the intervals between the clock bits 53 and 54 are reduced in the radial direction of the disk, and the clock bits are recorded with high density.

In FIG. 5(b), by simultaneously using the first and second laser beams 41, 42 when recording tarok bits, continuous clock bits 55 are recorded in the disk radial direction, as in FIG. 3(b). ing.

FIG. 6 shows an example in which first and second laser beams 61 and 62, which are circular beams arranged in the track direction, are used. In this case, as in FIG. 3(e), the track pitch of the clock bit is reduced to 1/2, and the wobbled bit 7 is irradiated with the first laser beam 61 as shown in FIG.
1.72 and records the clock bit 73 formed by the second laser beam 62 located on the original track centerline, and the clock bit 73 formed by the second laser beam 62 located between the original tracks. The clock bits 74 formed by beam 62 are recorded as V. Thus, clock bits 73,74 with respect to the disk radial direction
Clock bits are recorded at high density by reducing the interval between them.

Figure 8 shows an example in which first and second laser beams 81 and 82 are made up of circular beams arranged in the disk radial direction at intervals corresponding to the wobble H (1/2 track pitch) of the wobbled pits. be.

FIG. 9 shows a servo pattern recorded using laser beams 81 and 82 having the beam shape and arrangement as shown in FIG. 8. In FIG. 9(a), a wobbled pit 91 is By beam 81, wobbled pit 9
Clock bits 93° and 94 were recorded using the first and second laser beams 81° and 82, respectively.

In FIG. 9(b), the track pitch is reduced to 1/2 with respect to the clock pid, and a laser beam 81.82 is used to place the clock bit 93.94 at a position centered on the original track.
A clock bit of 95.96 was recorded by a laser beam of 81.82 between the original tracks.

FIG. 10 is an example in which the distance between the first and second laser beams 81 and 82 in FIG. 8 is widened.

FIG. 11 shows a servo pattern recorded using laser beams 81 and 82 having the beam shape and arrangement as shown in FIG.
By recording clock bit 92 and also recording clock bit 97.98 using both laser beam 81.82,
97.98 clock bits are recorded at high density in the radial direction of the disk.

Note that the present invention is not limited to the above-mentioned embodiments, and the method of the present invention can also be applied to an apparatus for recording servo patterns on an optical card. Furthermore, an EO (electro-optical) modulator may be used instead of the AO modulator used in the embodiment.

In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[Effects of the Invention] According to the present invention, when recording a servo pattern consisting of wobbled bits and clock bits on an optical memory master,
In particular, the clock bits can be recorded substantially perpendicularly to the track direction longer than the wobbled bits, or in a continuous manner, or in a higher density.

If a sample servo format optical memory is created using a master disk on which servo patterns are recorded in this way, when obtaining servo information from the optical memory, reflected light from adjacent tracks will leak when on-track and off-track. Since the difference in amount is reduced and the difference in the degree of modulation of the detection signal is also reduced, it is possible to stably extract the clock signal even when off-track.

[Brief explanation of drawings]

FIG. 1 shows a servo pattern recording device for an optical disk master according to an embodiment of the present invention, and FIG. 2 shows a first example of the shape and arrangement of the first and second laser beams used in the present invention. 3 shows a servo pattern recorded by the laser beam in FIG. 2, and FIG. 4 shows a second example of the shape and arrangement of the first and second laser beams used in the present invention. 5 shows the servo pattern recorded by the laser beam in FIG. 3, and FIG. 6 shows the servo pattern recorded by the laser beam in FIG.
FIG. 7 is a diagram showing a servo pattern recorded by the laser beam of FIG. 6, and FIG. 8 is a diagram showing a third example of the shape and arrangement of the second laser beam. A diagram showing a fourth example of the shape and arrangement of the second laser beam, FIG. 9 is a diagram showing a servo pattern recorded by the laser beam of FIG. 8, and FIG. 11 is a diagram showing a servo pattern recorded by the laser beam in FIG. 10, and FIG. 12 is an example of an optical disc using the sample servo format method. The figure shown in FIG. 13 is a diagram showing a servo pattern in a conventional sample servo format. 1... Optical disk, 2... Servo area, 3... Data area, 11, 12, 31, 32, 51.52°71
．． 72,91.92...wobbled bit (first signal), 13.33~36.53~55°73.74.9
3 to 98...Clock bit (second signal) 21
, 41, 61.81...first laser beam, 22,
42.62', 82... second laser beam. Applicant's representative Patent attorney Takehiko Suzue Figure 3 Figure 4 Figure 6

Claims (3)

[Claims] (1) In a method in which an energy beam is irradiated onto the optical memory master disk and a first signal distributed to the left and right sides of the track and a second signal located at least partially on the track center line are recorded as a servo pattern. , a servo pattern for an optical memory master, characterized in that a first signal is recorded by a first energy beam, and a second signal is recorded by a second energy beam whose dimension in the track width direction is larger than the dimension in the track direction. Recording method. (2) In a method in which an energy beam is irradiated onto the optical memory master disk and a first signal distributed to the left and right sides of the track and a second signal located at least partially on the track center line are recorded as a servo pattern. , using first and second energy beams arranged substantially perpendicular to the track direction, the first signal is recorded by the first energy beam, and the second signal is recorded by the first and second energy beams. A servo pattern recording method for optical memory master discs, which is characterized by: (3) In a method in which an energy beam is irradiated onto the optical memory master disk and a first signal distributed to the left and right sides of the track and a second signal located at least partially on the track center line are recorded as a servo pattern. , whether the second signal is recorded longer than the first signal in a direction substantially perpendicular to the track direction, or whether it is recorded continuously;
Or a servo pattern recording method for optical memory master disks, which is characterized by high-density recording.