JP2743920B2 - disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information relates to a recording or reproduction of the discs of the (signal), in particular pin <br/> Tsu preparative modulation in reproducing pit signal modulation degree (the tracking error signal and pit ) Is substantially flat.

[0002]

2. Description of the Related Art As a tracking system in an information recording / reproducing apparatus using an optical disk, there are a continuous servo system and a sample servo system. 1 for these methods
"Dual Feature of Continuous Groove Method and Sample Servo Method" described on pages 163 to 170 of Nikkei Electronics published on December 15, 986, and Showa 62
It is described in "Optical Disc Standardization Trend Explanatory Meeting Materials" issued by the Optoelectronic Industry and Technology Promotion Association's Optical Disc Roundtable and Information Processing Society of Japan Information Standards Investigation Committee published on December 3, 2012. The continuous groove servo method is a method that has been developed for a long time. On the other hand, the sample servo method is a method that has been actively developed recently because attention is paid to its good tracking stability.

An optical disk used for a conventional sample servo type recording / reproducing apparatus will be described with reference to FIG.

FIG. 2 shows a schematic plan view of an optical disk and a partially enlarged view thereof. As shown in the figure, tracks 17 and 1 are placed on a reading surface 16 of a disk substrate 11 of the optical disk.
8 are provided. An optical head (not shown) of the recording / reproducing apparatus travels on the tracks 17 and 18.
In the sample servo method, tracking sample marks 12 and 13 are provided on tracks 17 and 18 respectively. The sample marks 12 and 13, arranged distributed in the radial direction of the disc around a track 17, 18 are formed as a wobble pin Tsu bets.

[0005] The optical head was the wobble pin Tsu door 12,
Tracks 17 and 1 indicate that the amount of reflected light from
8, and this point is set as the traveling position. The tracks 17 and 18 indicated by broken lines are examples of arrangement, and a large number of tracks 17 and 18 are actually provided. The local enlarged view of FIG. 2, the wobble pin Tsu sheet 1 in the other tracks
2, 13 are also described. The clock pin Tsu door 14
It is provided in order to perform the detection of the data pins Tsu bets to be recorded (not shown) after the recording and reproducing apparatus. Further, the disk substrate 11 is a replica substrate made of plastic or glass.

[0006] The wobble pin Tsu door 12 and 13 and the clock
Disk circumferential length of the pin Tsu bets 14, i.e. Pi Tsu DOO length l becomes 90ns in terms of travel time of the optical head. Actual dimensions of pin Tsu DOO length l is the disk radius r and 30 mm, is about 0.5μm When 1800rpm rotational speed of the optical disk. Also when the disk radius r to 60 mm, pin Tsu DOO length l is approximately 1.0 .mu.m.

On the other hand, the optical depths of these pins Tsu metropolitan,
If the wavelength of the reading laser used in the optical head is λ, it is λ / 4. Here, the wavelength λ is usually selected to be 830 nm. Such pin Tsu preparative sample mark area provided in one revolution (one track) per 1000-3
000 locations are required, usually 1376 locations. Further, there are 32 portions other than the sample mark area, that is, 32 sector address portions 15 in one track. The sector address section 15 is provided with a pit (not shown) indicating an address.

[0008] The wobble pin Tsu preparative 12, 13 and the clock of the optical disc corresponding to such a sampled servo system
Pi Tsu DOO 14, similar to the video disc or compact disc, formed by on the master, such as plastic or glass to form a photoresist film is irradiated with cutting laser beam finely focused to develop a master after irradiation Is done. The irradiation power P _B of the cutting laser light by the cutting machine is represented by P _B = Jv, where V is the linear velocity at an arbitrary point on the reading surface of the master optical disc, and J is the irradiation density of the laser light. Controlled to meet.

[0009] Figure 3 for pin Tsu preparative length l of this case, the disk radial pin Tsu-wide (hereafter, referred to as a pit width) W
Shows the measured values. As can be seen from FIGS. 2 and 3, pin Tsu preparative length l is the even greater peak <br/> Tsu-wide W longer for normal cutting machine. Therefore, in the optical disc of the sample servo method used by rotating at a constant angular velocity, as shown in FIG. 2, the wobble pin Tsu preparative 12,1
Pit length l of 3 and a clock pin Tsu DOO 14 becomes different between the inner and outer peripheries of the optical disc. Similarly, the pit width W differs between the inner and outer circumferences. For that matter, if Pi Tsu preparative length l which is formed on the reading surface of the optical disk is smaller than the beam spot diameter of the cutting laser beam, Pi Tsu-wide that pin <br/> Tsu preparative length l is formed shorter W becomes narrower.

[0010]

In the above prior art,
The manufacturing time of the master for an optical disk, is formed differently in the inner periphery of the pin Tsu preparative length l and width W TogaHikari disk. That is, peak Tsu bets increases in the outer peripheral side. For this, the phenomenon of peak Tsu preparative signal modulation (tracking error signal and pit modulation) would change occurs within the recording area on the surface reading at the time of reproducing the optical disc. That is, the prior art has not considered this point.

An object of the present invention is to provide a disk having a pit signal modulation degree which is substantially flat.

[0012]

SUMMARY OF THE INVENTION The above object is achieved by a disk having a plurality of pits, a width of the disk radial direction of pits is provided in the innermost periphery of the pit sac Chide disk radial direction This is achieved by making the length longer than the length in the disk circumferential direction.

[0013]

[Action] Pi Tsu preparative area and peak Tsu preparative signal modulation degree in FIG. 4 (a tracking error signal and the pit modulation factor) experimental data representing the relation between are shown. According to FIG. 4, the tracking error signal and the peak Tsu DOO modulation has a maximum value respectively pin Tsu preparative area, these variation with respect to a change in peak Tsu DOO area near the maximum value (differential value) is It is getting smaller.

Therefore, the tracking error signal and
The pin Tsu bets modulation degree substantially constant at the variation is small state, it is effective to set the peak Tsu bets on pin Tsu preparative area corresponding to these maximum values. Also, peak <br/> Tsu preparative length l of the disk circumferential direction is different in the inner periphery of the disk radial direction is longer than the pin Tsu preparative length li of the inner peripheral side pin Tsu bets length lo of the outer peripheral side. As a result, the relationship between the pit width Wi and the pit width Wo of the inner circumferential pits in the radial direction of the disc is determined by Wi> Wo while forming the pits on the disc master while maintaining the pit area substantially constant (hereinafter referred to as "means ( a) "hereinafter.) by employing the inner if peripheral side pin Tsu-wide Wi longer than the outer peripheral side pin Tsu <br/>-wide Wo and the inner periphery of the pin Tsu preparative area and the outer periphery side it can be made substantially the same and a peak Tsu preparative area.

[0015] Incidentally, the peak Tsu preparative length lo and pin Tsu-wide Wi same size, and it is preferable to set the peak Tsu preparative length li and the pin Tsu-wide Wo identical dimensions. Further, in FIG.
Since the tracking error signal when pin Tsu preparative area a (l × W) of about 0.35 .mu.m ² is substantially constant preferred. Furthermore, if the interval Tr of tracks is large enough, it is also possible to employ a pin Tsu preparative area located in the middle between the maximum value and the maximum value of Pi Tsu bets degree of modulation of tracking error signal.

Furthermore, experimental data representing the relation between the peak Tsu-wide W and the tracking error signal is shown in FIG. Here pin Tsu door length l is about 0.5~1.0μm. As can be seen from FIG. 5, the tracking error signal has a maximum value with respect to pin Tsu-wide W, variation is reduced in the vicinity of the maximum value with respect to the change of the peak Tsu <br/>-wide W ing. Therefore, in the constant tracking error signal with little variation in the state, the optimum value Pi Tsu-wide (the value of the peak Tsu-wide corresponding to the maximum value of the tracking error signal) is present. Means for forming pits on a master disc (hereinafter referred to as "means (B)"), with the relationship between the pit width Wi of the inner pit and the pit width Wo of the outer pit being WiＷWo.
The employed need only be substantially constant around the optimum value Pi Tsu-wide W. Then, the optimal value of the peak Tsu-wide W in FIG. 5 is approximately 0.5 [mu] m. Although not shown,
As will be described later, it has been confirmed that the pit modulation degree becomes substantially constant by making the pit width W substantially constant near the optimum value.

The measurement data of FIGS. 4 and 5 are as follows. Pi Tsu For preparative forms specifications, numerical aperture NA of about 0.7 of an objective lens (described later), the beam spot diameter φ is approximately 0 the intensity of the laser light is diameter reduced to 1 / e ² spot center 0.9 μm, the track pitch Tr is 1.
5 [mu] m, peak Tsu DOO length l of about 0.5 to 1.0 [mu] m, the optical peak <br/> Tsu preparative depth (lambda / 4) is a refractive index of about 1.59 of poly Capo sulfonate as a disk substrate When used, about 13
0.0 nm. Also, regarding the reproduction optical system specifications, N
A is about 0.5, the laser wavelength λ is about 830 nm, the laser beam diameter φ is about 1.5 μm, and the beam cross-sectional area is about 1.8 μm ² .

Here, a pit forming method will be described.
First, the rotation means, so rotates the linear velocity at radial position on the surface of the master disk as a predetermined value v, the position of the master to form the pin Tsu bets is updated. Since the laser irradiation means for irradiating the cutting laser beam on the position of the master to form the pin Tsu bets, to form a pin Tsu bets on the master. Since irradiation power control means controls the irradiation power of the cutting laser beam function _{(J 1 v + J 0 '} ), depending on the position of the disk radial direction, to change the size of the pin Tsu bets to be formed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic plan view and a partially enlarged view of a sample servo type optical disk according to a first embodiment of the present invention. In Figure 1, the disk substrate 1 is made of poly Capo sulfonate (PC), an inner diameter phi ₁ of the hole 6 provided in its center 15 mm, outer phi ₀ of the disc substrate 1 is 130 mm, the thickness t is 1.2mm The data area 7 has a radius r in the range of 30 to 60 mm. The track pitch Tr is 1.5 [mu] m, the optical peak Tsu preparative depth (lambda /
4), assuming that the refractive index of PC is about 1.59, about 130.
0 nm. Here, the laser wavelength λ is 830 nm. A helium cadmium (He-Cd) laser generator having a laser wavelength λ ₀ of 441.6 nm is used as a laser light source for cutting. A positive resist is used as the photoresist. Reference numeral 5 in the figure denotes a sector address portion similar to 15 in FIG.

The local enlarged view shown at the bottom of FIG. 1 shows a part (r) of a track at a radius r = 30 mm on the horizontal axis side.
30) and a part (r60) of the track at a radius r = 60 mm, and the vertical axis represents the means (A) and the means (B) employed.

[0022] Here, the 2 and 3 have the same wobble pin Tsu bets and 12, 13 of FIG. 2, 4 is the same clock pit 14 of FIG. First, the case where the above-described means (A) is employed will be described. Relationship between the peak Tsu-wide Wo = W ₂ of pins <br/> Tsu-wide Wi = W ₁ and r60 parts of r30 parts in this case is to set the W1> W2. Incidentally, by setting approximately 0.7μm inner circumferential side pin Tsu-wide W1, the outer peripheral side pin Tsu-wide W ₂ of about 0.35μm forming a pin Tsu bets in this embodiment, pin Tsu <br/> The surface area was kept constant at approximately 0.35 μm ² .

[0023] Now, it will be described a method of forming a peak Tsu bets predetermined area. Generally pin Tsu bets size is proportional to the irradiation power P of the laser light during cutting. Further, as shown in FIG. 3, to form a pin Tsu bets by conventional irradiation power control method (P _B = Jv), narrows the inner circumferential side pin <br/> Tsu-wide Wi, the outer peripheral side pin Tsu G. The width Wo increases. Therefore, a method of setting the irradiation power P to a constant J ₀ ≒ 2.7 mJ is adopted as the irradiation power control method, and cutting is performed on the rotated disk master. As a result, pin Tsu door area is almost constant, the relationship between the pin Tsu door width W
_1> W ₂ become. As a result, in the recording area, about a tracking error signal and the peak Tsu bets modulation respectively 40
%, About 70%.

In the first embodiment described [0024] above, peak <br/> Tsu is the door area was 0.35 .mu.m ² constant, peak Tsu preparative area 0.2 to 0.8 [mu] m ² even sufficient tracking error signal and peak Tsu bets modulation degree is obtained. Pi Tsu DOO area when this is equivalent to 10-45% of the beam area 1.8 .mu.m ² of the reproducing light.

[0025] Incidentally, it has dealt with the case of controlling the size of the irradiation power P as irradiation power control method, to obtain a constant peak <br/> Tsu preparative area by controlling the pin Tsu preparative cutting time T Can be.

[0026] A conventional pin Tsu door cutting time T ₀ = 90
Correction for ns (control) pin Tsu bets cutting time after T _A, T _B, a time chart in FIG. 7 for T _D.
In FIG. 7, the horizontal axis represents time, and the vertical axis represents the irradiation of the cutting laser light. Conventional pin Tsu preparative cutting time T ₀ is indicated by a broken line. In addition, in this time chart, the wobble from the left side pin Tsu Doo 2
The peak Tsu preparative cutting time T _0, the time T ₀ of the wobble pin Tsu bets 3, described in the order of time T ₀ of the clock pin Tsu bets 4. 7 (a) is pin Tsu bets cutting time at r30 parts T _A =
This indicates 120 ns.

FIG. 7B shows the radius r = 45 m of the optical disk.
Pi Tsu DOO cutting time in the portion of the track in the m (r45 parts) shows the T _B = 85ns. FIG.
(C) the peak Tsu bets cutting time at r60 parts T _D = 5
0 ns. Thus the time T ₀ with the value of the radius r of the optical disk, the time T _A, T _B, when going to correct the T _D is also substantially constant peak Tsu preparative area (0.35 .mu.m ²⁾ is obtained Can be

Next, referring to FIG.
The case where is adopted will be described. In this case, r30
Part of the pin Tsu-wide Wi = W ₃ and r60 parts of the pin Tsu-wide Wo = W ₄
Is set such that W ₃ ≒ W ₄ . Incidentally, to form a pin Tsu preparative set to W ₃ ≒ W ₄ ≒ 0.5μm in this embodiment.

[0029] now be described with reference to FIG. 6 method for forming a pin Tsu City of predetermined peak Tsu-wide W. FIG. 6 shows the laser irradiation power P with respect to the disk radius r for each irradiation power control method. The broken line in the figure indicate the conventional irradiation power control scheme (P _B = Jv), irradiation power control method of the solid lines present invention used in the case of producing a pin Tsu City of predetermined area (P = J ₀ ). The one-dot chain line in FIG.
It was used in order to fix the pin Tsu-wide W, indicating the irradiation power control method of the present invention _{(P = J 1 v + J} 0 ').
Here, J ₁ and J ₀ ′ are irradiation densities of laser light. In this method (P = J ₁ v + J ₀ ), J ₁ ≒ 0.65 m
Cutting was performed on the master disc rotated by setting J, J ₀ ′ ≒ 1.7 mJ. In this manner, when performing the cutting, the pin Tsu-wide W is substantially constant, the relationship of Pi <br/> Tsu-wide is the W ₅ ≒ W _4. As a result, in the recording area, about 35% to 40% the tracking error signal and the peak Tsu bets modulation, respectively, could be produced substantially constant optical disk and approximately 60-80%.

[0030] Incidentally, it was possible to substantially obtain a constant peak Tsu-wide W by controlling the pin Tsu preparative cutting time T. This is applied to the case of FIG.
Rain Tsu door cutting time in the part T _A is 120ns, r4
Rain in 5 parts Tsu door cutting time T _B is 105ns, r
Pi Tsu DOO cutting time T _D in 60 parts becomes 90ns. Thus the conventional pin Tsu preparative cutting time T ₀ with the value of the radius r of the optical disk, the time T _A, T _B, T
When it is going to correct the _D also substantially constant peak Tsu-wide (0.5 [mu] m) is obtained.

Further, on the reading surface of the optical disk in the above embodiment, pin Tsu bets circular or pin Tsu-wide W from pin Tsu preparative length l
Has been described what is long, the beam spot diameter smaller than the shortest pin Tsu preparative the disk circumferential direction of the cutting laser beam (track direction), Pi Tsu-wide W is
Be formed long pin Tsu preparative than Pi Tsu preparative length l can be constant at the inner periphery of the pin Tsu-wide W. This embodiment is shown in FIG.

[0032] Figure 8 is a shows a schematic plan view and a local enlarged view of an optical disc as in FIG. 2, the disc substrate 81, 82 and 83 wobble pin Tsu DOO, 84 clock pin Tsu DOO, 85 is a sector address part. This FIG.
It can be obtained a substantially constant optical disks peak Tsu preparative signal modulation system in the embodiment. Furthermore, so that the beam spot size at the time of cutting the same and minimum peak Tsu preparative length, the same effect can go narrow with an optical system is obtained.

[0033] Now, the cutting machine to be used for peer Tsu preparative formation of the optical disk of the present invention will be briefly described by way of example.

FIG. 9 is a configuration diagram of a cutting machine used in the present invention. In the illustrated cutting machine, in forming a pin <br/> Tsu DOO, first, reading the glass master 28 having the photoresist film 29 on the surface, using a rotating means (not shown.), The rotation center axis 30 Rotate around. Further, the head moving unit 25 including the optical deflector 26 and the objective lens 27 is moved in the radial direction as the glass master 28 rotates. Here, the movement of the head moving unit 25 is equivalent to one track pitch in one rotation.
In such an operation state of the mechanical system, the helium-cadmium (He-Cd) laser generator 21 emits the laser light 20.
Is output. The laser light 20 passes through the irradiation power controller 22, the mirror 23, the collimator lens 24, the light modulator 31, the collimator lens 32, and the mirror 33, and sequentially enters the head moving unit 25. The laser beam 20 ′ incident on the head moving section 25 is irradiated on a photoresist film 29 via an optical deflector 26 and an objective lens 27. As a result the cutting is performed as is not being peer Tsu bets formation.

The control of the laser irradiation power P (P = J ₁ v + J ₀ ′) described in FIG. 6 and the like is performed by the irradiation power controller 22. The linear velocity v was set based on the position of the head moving unit 25 detected by a potentiometer (not shown) and based on the detected value (however, the method is not limited to this). Further, the optical modulator 31 at the timing shown in pin Tsu preparative cutting time T _C in Figure 7, irradiation on the laser beam 20 for cutting, the control of the irradiation off (modulation)
I do. Then, the laser light 20 ′ modulated by the light modulator 31 is deflected by the light polarizer 26. This deflection, there is carried out only when forming a wobble pin Tsu bets, at symmetrical positions in the disk radial direction around the track, is performed to irradiate the cutting laser beam.

[0036]

According to the present invention, it can be made substantially constant peak Tsu preparative signal modulation (flat), can provide a high-quality optical disk.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and a partially enlarged view of an optical disc of an embodiment according to the present invention.

FIG. 2 is a schematic plan view and a partially enlarged view of a conventional optical disk to which a sample servo method is applied.

FIG. 3 is a characteristic diagram for explaining the present invention.

FIG. 4 is a characteristic diagram for explaining the present invention.

FIG. 5 is a characteristic diagram for explaining the present invention.

FIG. 6 is a characteristic diagram for explaining the present invention.

FIG. 7 is a characteristic diagram for explaining the present invention.

FIG. 8 is a schematic plan view and a partially enlarged view of an optical disc of an embodiment according to the present invention.

9 is a block diagram showing an example of a cutting machine used to pin Tsu preparative formation of the optical disk of the present invention.

[Explanation of symbols]

1, 11, 81 ... disk substrate, 2, 3, 12, 13,
82, 83 ... wobble pin Tsu door, 4,14,84 ... clock pin Tsu door, 5,15,85 ... sector address section.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Ishigaki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi Nichido Seisakusho Home Appliances Research Institute (72) Inventor Yukio Fukui 292 Yoshida-cho, Totsuka-ku, Yokohama-shi Nichichi Seisakusho Inside the Home Appliance Research Laboratory (56) References JP-A-61-214149 (JP, A)

Claims (2)

(57) [Claims] 1. A disc having a plurality of pits,
Disks width of the disk radial direction of pits is provided in the innermost periphery of the pit sac Chide disk radial direction is equal to or longer than the length of the disk circumferential direction. 2. The disk according to claim 1, wherein the width of the pits provided on the inner peripheral side in the radial direction of the disk is substantially equal to the width of the pits provided on the outer peripheral side.