JP2786659B2 - Method and apparatus for recording servo pattern on optical memory master - Google Patents

Description

Description: Object of the Invention (Industrial Application Field) The present invention relates to a method and an apparatus for recording a servo pattern on a master used for manufacturing an optical memory such as an optical disk, and particularly to a sample servo format. And a method and apparatus for recording a servo pattern on an optical memory master.

(Prior Art) A sample servo format is known as one of the recording formats of an optical disc. This divides a concentric or spiral track on the optical disk 1 into a servo area 2 and a data area 3 as shown in FIG. 12, and records a servo pattern as shown in FIG. Things.

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

Such an optical disk is manufactured using a master on which a servo pattern is recorded in advance. Conventionally, when a servo pattern is recorded on a master, a single laser beam is used, and the laser beam is deflected by a 1/4 track pitch using an AO modulator or an EO modulator to irradiate the master disc with wobble. Dots are recorded, and clock pits are recorded by irradiating the laser beam without deflecting it.

However, in an optical disk manufactured using the master on which the servo pattern is recorded in this manner,
When the reflected signal from the clock pit is detected during reproduction to extract the clock signal, the degree of modulation of the detection signal (amplitude of the detection signal) is compared with that during on-track when the laser beam irradiation position is off-track. ) Is significantly reduced. For example, when a clock pit having a depth of 1300 mm and a width of 0.6 μm is formed at NA = 0.6, laser beam filling rate 1.0, λ = 830 nm, track pitch 1.5 μm, depth 1300 °, width of the detection signal from the clock pit is on-track. At times it is 80% compared to 10% off-track.

If the modulation degree of the detection signal decreases to this level, it becomes difficult to extract the clock signal. The reason for the difference in the modulation degree of the detection signal between the on-track time and the off-track time is because there is a difference in the amount of reflected light leaking from the adjacent track.

(Problems to be Solved by the Invention Glass) As described above, according to the conventional servo pattern recording technique of an optical memory master, when a signal is reproduced from an optical memory, the modulation degree of a detection signal from a clock pit is significantly reduced in an off-track state. As a result, there is a problem that it is difficult to extract the clock signal.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for recording a servo pattern on an optical memory master, which can form a clock pit on an optical memory so that a clock signal can be stably extracted even during off-track.

[Configuration of the invention]

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

As a result, the clock pits are recorded in a direction substantially perpendicular to the track direction longer than the wobbled pits, continuously, or at a high density.

(Operation) When the clock pits are elongated on the optical memory master in the direction substantially perpendicular to the track direction, are continuously formed, or are recorded at a high density in this manner, when the signal is reproduced from the optical memory, the on-track time and the on-track time are reduced. The amount of leakage of the reflected light from the adjacent track decreases during the track, and the difference in the modulation degree of the detection signal also decreases. As a result, the clock signal can be stably extracted even during off-track.

(Example) Hereinafter, an example of the present invention is described with reference to drawings.

FIG. 1 shows a recording apparatus for a master optical disc according to an embodiment of the present invention. In FIG. 1, a laser light source 1 is, for example, an Ar ⁺ laser, and a laser beam emitted from the laser light source 1 is split into two by a half mirror 102 and a mirror 103. The first laser beam is a convex lens 104, AO
(Acousto-optic) modulator 106, slit plate 108 and convex lens 11
Similarly, the second laser beam is guided to the mirror 112 via the convex lens 105, the AO modulator 107, the slit plate 109 and the convex lens 111.

The first laser beam reflected by the mirror 112 is A
The light is deflected by the O modulator 114, further guided by a mirror 115, guided to convex lenses 116 and 117, and enters a polarization beam splitter 124.

On the other hand, the second laser beam reflected by the mirror 113 includes a mirror 118, a cylindrical lens 119, and a convex lens.
The light passes through a beam shaping system including a slit plate 121, a slit plate 121, and a convex lens 122, is further guided by a mirror 123, and is incident on a polarization beam splitter 124.

The first and second laser beams guided on the same optical path by the polarizing beam splitter 124 are focused and irradiated on the optical disk master 127 by the objective lens 126 while being guided by the mirror 125, and record a servo pattern.

The optical disc master 127 has, for example, a structure in which a resist layer is formed directly or through an adhesion layer on a glass disc, a metal layer is formed on a glass disc, and a resist layer is formed thereon directly or through an adhesion layer. A configuration in which a resist layer is formed directly or through an adhesion layer on a metal disk, or a configuration in which a metal layer is formed on a metal disk and a resist layer is formed thereon directly or through an adhesion layer Has become.

FIG. 2 shows the beam shapes and arrangements of the first and second laser beams 21 and 22 focused and irradiated onto the optical disk master 127 by the configuration of FIG. 1. The first laser beam 21 The circular beam and the second laser beam 22 have a shape that is long in a direction substantially perpendicular to the track direction (circumferential direction) (radial direction of the disk) (hereinafter, referred to as a horizontally long beam). These laser beams 21 and 22 are arranged in the track direction.

Note that the shape of a horizontally long beam such as the second laser beam 22 is obtained by a beam shaping system including a beam expander including a cylindrical lens 119, a convex lens 120, and a convex lens 122 in FIG. Can be 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 second beam shape and arrangement. First, in FIG. 3A, the first laser beam
By deflecting 21 to both sides of the track by the AO modulator 114, wobbled pits 31 and 32 are recorded, and a horizontally long clock pit 33 formed by the second laser beam 22 is recorded on the track center line. ing.

In FIG. 2B, wobbled pits 31 and 32 are recorded in the same manner, and clock pits 34 continuous in the disk radial direction are recorded. In order to record such continuous clock pits 34, the width of the second laser beam 22 in the disk radial direction is set to a size (for example, about 2 μm) such that the bit formed by the laser beam 22 overlaps an adjacent pit. You can choose.

In FIG. 3 (c), the wobbled pits 31 and 32 are recorded in the same manner, and when recording the clock pit, the track pitch is halved, and the first pit is placed on the original track center line.
A clock pit 35 formed by the laser beam 21 is recorded, and a horizontally long clock pit 36 formed by the second laser beam 22 between the original tracks.
Is recorded. That is, the interval between the clock pits 35 and 36 is reduced in the disk radial direction, and the clock pits are recorded at a 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. As in FIG. 2, the first laser beam 41 is a circular beam, The laser beam 42 has a shape of a horizontally long beam that is long in the radial direction of the disk. In this example, these laser beams 41 and
42 are arranged in the disk radial direction, that is, in the direction substantially perpendicular to the track direction.

FIG. 5 shows a servo pattern recorded using the laser beams 41 and 42 having the beam shape and arrangement as shown in FIG. In FIG. 5 (a), the wobbled pits 51 and 52 are in the third position.
Recording by the first laser beam 41 as in the case of the figure,
As in the case of FIG. 3 (c), the clock pit 53 formed by the first laser beam 41 on the original track center line and the second laser A horizontally long clock pit 54 formed by the beam 42 is simultaneously recorded. As a result, the clock pits 53 and 54 are
And the clock pits are recorded at a high density.

In FIG. 5B, a clock pit 55 continuous in the disk radial direction is recorded as in FIG. 3B by simultaneously using the first and second laser beams 41 and 42 at the time of recording the clock pit. doing.

FIG. 6 shows an example in which first and second laser beams 61 and 62 composed of circular beams arranged in the track direction are used.
In this case, the track pitch of the clock pit is halved in the same manner as in FIG. 3C, and the wobbled pits 71 and 72 are formed by the first laser beam 61 as shown in FIG. Clock pit formed by the second laser beam 62 located on the original track center line
73, and a clock pit 74 formed by the second laser beam 62 and located between the original tracks. As described above, the interval between the clock pits 73 and 74 is reduced in the disk radial direction, and the clock pits are recorded at a high density.

FIG. 8 shows first and second laser beams 8 composed of circular beams arranged at intervals corresponding to the amount of wobble of wobbled pits (1/2 track pitch) in the radial direction of the disk.
This is an example using 1,82.

FIG. 9 shows a servo pattern recorded by using the laser beams 81 and 82 having the beam shape and arrangement as shown in FIG. 8. In FIG. 9 (a), the wobbled pit 91 is formed by the first laser. Second wobbled pit 92 by beam 81
And the clock pits 93 and 94 are recorded by 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 pits, and the position clock pits 93 and 94 centered on the original tracks are recorded by the laser beams 81 and 82, and further, between the original tracks Also laser beam 81,8
2, the clock pits 95 and 96 are recorded.

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

FIG. 11 is a servo pattern recorded using laser beams 81 and 82 having the beam shape and arrangement as shown in FIG.
The wobbled pits 91 and 92 are recorded by the laser beam 81, and the clock pits 97 and 98 are recorded by using both the laser beams 81 and 82, whereby the clock pits 97 and 98 are recorded.
At a high density in the radial direction of the disk.

It should be noted that the present invention is not limited to the above embodiment, and the method of the present invention can be applied to an apparatus for recording a servo pattern on an optical card. Further, an EO (electro-optic) modulator may be used instead of the AO modulator used in the embodiment.

In addition, the present invention can be variously modified and implemented without departing from the gist.

〔The invention's effect〕

According to the present invention, when recording a servo pattern composed of wobbled pits and clock pits on an optical memory master, in particular, the clock pits are made longer or continuous than the wobbled pits in a direction substantially perpendicular to the track direction, or Recording can be performed at a high density.

When an optical memory of the sample servo format is manufactured using the master on which the servo pattern is recorded in this way, when servo information is obtained from the optical memory, the reflected light leaks from the adjacent track during on-track and off-track. Since the difference in the amount decreases and the difference in the modulation degree of the detection signal also decreases, the clock signal can be stably extracted even during off-track.

[Brief description of the drawings]

FIG. 1 shows a servo pattern recording apparatus for an optical disk master according to one embodiment of the present invention, and FIG. 2 shows a first example of the shapes and arrangements of first and second laser beams used in the present invention. FIG. 3 is a diagram showing a servo pattern recorded by the laser beam of FIG. 2, and FIG. 4 is a diagram showing a second example of the shape and arrangement of the first and second laser beams used in the present invention. FIG. 5 is a view showing a servo pattern recorded by the laser beam shown in FIG. 3, and FIG.
FIG. 7 is a diagram showing a third example of the shape and arrangement of the second laser beam, FIG. 7 is a diagram showing a servo pattern recorded by the laser beam of FIG. 6, and FIG. FIG. 9 is a view showing a fourth example of the shape and arrangement of the second laser beam, FIG. 9 is a view showing a servo pattern recorded by the laser beam of FIG. 8, and FIG. FIG. 11 is a view showing a fifth example of the shape and arrangement of the laser beam of FIG. 2, FIG. 11 is a view showing a servo pattern recorded by the laser beam of FIG. 10, and FIG. FIG. 13 is a diagram showing a servo pattern in a conventional sample servo format. 1 ... optical disc, 2 ... servo area, 3 ... data area, 11, 12, 31, 32, 51, 52, 71, 72, 91, 92 ... wobbled pit, (first signal), 13 , 33-36,53-55,73,74,93
~ 98 ... clock pit (second signal), 21,41,61,81
... First laser beam, 22, 42, 62, 82... Second laser beam.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/00 G11B 7/26 G11B 7/24 563

Claims (5)

(57) [Claims] An energy beam is radiated onto an optical memory master, so that the first light beam is distributed to the right and left of the track.
And a second signal, at least a part of which is located on the track center line, is recorded as a servo pattern. The first signal is recorded by a first energy beam, and the second signal is recorded in a track width direction. Recording with a second energy beam having a dimension larger than the dimension in the track direction. 2. The method according to claim 1, further comprising: irradiating an energy beam onto the master optical memory to thereby divide the first track divided into right and left tracks.
And a second signal, at least a part of which is located on the track center line, is recorded as a servo pattern, using the first and second energy beams arranged substantially vertically in the track direction. Recording a signal with a first energy beam, and recording a second signal with a first energy beam and a second energy beam. 3. An optical memory master disc is irradiated with an energy beam, so that the first disc is divided into right and left tracks.
And a second signal, at least part of which is located on the track center line, is recorded as a servo pattern. In the method, the size of the second signal is larger in the direction substantially perpendicular to the track direction than in the first signal. , Or continuously,
Alternatively, a method for recording a servo pattern on an optical memory master, wherein recording is performed at a high density. 4. An optical memory master is irradiated with an energy beam, so that the first light beam distributed to the left and right of the track is separated.
And a second signal at least partially located on the track center line, as a servo pattern, means for recording the first signal with a first energy beam, and recording the second signal on a track. Means for recording with a second energy beam having a dimension in the width direction larger than the dimension in the track direction. 5. The method according to claim 1, further comprising irradiating an energy beam onto the optical memory master, thereby arranging the first beam on the left and right of the track.
And a second signal having at least a part thereof located on the track center line as a servo pattern, comprising: means for generating first and second energy beams arranged in a direction substantially perpendicular to the track direction; Means for recording a first signal by a first energy beam; and means for recording a second signal by a first and a second energy beam. .