JP2001052343A - Optical disk and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk which is less in mark deviation, double copying, and ghost as an optical disk which uses a sample servo tracking system, and its manufacture. SOLUTION: This optical disk has a resin-molded substrate 11, and an enhancement film 12 formed of a dielectric thin film, a heat insulating film 14, a reflecting film 15, and a protective coat 16 which are laminated on the resin- molded substrate 11, which is 0.7 mm thick or smaller. Since the thickness of the resin-molded substrate is 0.7 mm or smaller, an optical disk which is less in mark deviation, double copying, and ghost is obtained as an optical disk which uses a sample servo tracking system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, an optical disk is mainly formed by injection molding. However, when a signal mark imprinted on a stamper is transferred to a molding substrate, the mark is displaced (mark shift), and the pitch is originally small. Marks were sometimes formed in the parts that should not be used (double transfer / ghost). These molding defects are one of the causes of the characteristic failure of the optical disk.

[0003] The mark misalignment and the double transfer / ghost appear remarkably especially on a resin molded substrate of a format employing a sample servo tracking system. FIG. 11 is a schematic plan view showing an example of a servo area of a conventional optical disk using the sample servo tracking method.

Referring to FIG. 11, a conventional optical disk is
A resin molded substrate 1 made of plastic such as polycarbonate is provided. In a servo area on the resin molded substrate 1, wobble marks 3 and 4 for tracking and a clock mark 5 are arranged along a virtual track center line 2. ing. As shown in FIG. 11, the sample servo tracking method does not use a guide groove for tracking, but includes tracking wobble marks 3 and 4 meandering along the virtual track center line 2.
The wobble marks 3 and 4 are arranged so as to be substantially equally displaced from the virtual track center line 2 on the left and right sides, and tracking can be performed by detecting the wobble marks 3 and 4 with a light spot.

The lengths of the wobble marks 3 and 4 and the clock mark 5 in the disk radial direction are, for example, 0.3 μm.
０．６0.6 μm. The optical depths of the wobble marks 3 and 4 and the clock mark 5 are both
A value near λ / (4 × n) (where λ is the reading laser wavelength and n is the refractive index of the disk).

[0006] A servo area as shown in FIG. 11 is required at 1,000 to 3,000 locations around the disk. The other portions are mirror surfaces except for the address portion, and the area occupied by marks (marks such as wobble marks and clock marks) in the entire optical disk is very small, about 10%.

When the resin molded substrate 1 of the optical disk having a small area occupied by the marks is formed by injection molding, the original marks (wobble marks 3 and 4 and clock mark 5) are double-transferred as shown in FIG. As a result, unintended marks such as the ghost marks 3a, 4a and 5a are formed. 3
In some cases, double or quadruple marks are formed. Such double transfer adversely affects the tracking signal, and there is a problem that tracking does not operate normally.

As a measure for preventing the above-described mark misalignment, double transfer and ghost, a servo area having wobble marks is provided with a plurality of grooves and / or continuous marks on the inner and outer peripheral sides (Japanese Patent Laid-Open No. 63-211
No. 137), a disk in which a concave groove is formed in the circumferential direction of the base body and is displaced in the radial direction of the base body with respect to the center of the recording track in the width direction (Japanese Patent Laid-Open No. 3-203826). One provided with an undercut portion of a V-groove or a chevron at the center of the outer peripheral end face in the thickness direction (Japanese Patent Application Laid-Open No. 1-160627), and undercuts other than the information recording area of the mirror surface facing the stamper One having an uneven portion (JP-A-1-306214) has been proposed. In addition, the amount of an additive (release agent) containing a component for increasing the surface tension with the stamper contained in the resin molding material is set to 0.01% by weight or less (Japanese Patent Laid-Open No. 5-109125). There has been proposed one in which the anchor effect between a molded substrate and a stamper is improved.
Further, molding is performed under molding conditions in which the final pressure of the injection compression before opening the mold is set lower than usual (Japanese Patent Application Laid-Open No. Hei 7-246644).
Publication).

[0009]

However, a servo area provided with a plurality of tracks on the inner and outer peripheral sides of the servo area, a concave area formed at a position displaced in the radial direction of the substrate body, In the case where the undercut concave and convex portions are formed other than the information recording area on the mirror surface facing the stamper, there is a problem that the area of the recordable area is reduced. Further, an additive (release agent) containing a component for increasing the surface tension with the stamper is added to 0.01%.
A method for improving the anchor effect by setting the weight% or less is to interweave an optical disk having a small area occupied by a mark in the entire optical disk and a resin molded substrate of the optical disk in which marks and grooves are arranged on the entire surface using the same injection molding equipment. In the case of injection molding (by simply changing the stamper), it is necessary to replace the resin pellets for molding, which necessitates unnecessary disposal of the molding resin, and also takes time to replace the molding resin. was there. A method of forming an undercut portion of a V-groove or a chevron at a central portion in a thickness direction of an outer peripheral end surface of a disk;
The method of molding under the molding conditions in which the final pressure of the injection compression before opening the mold is set to a pressure lower than usual has a problem that a sufficient improvement effect on mark misalignment, double transfer and ghost cannot be obtained.

[0010] In order to solve the above problems, an object of the present invention is to provide an optical disk using a sample servo tracking method, which has less mark shift, double transfer and ghost, and a method of manufacturing the same.

[0011]

In order to achieve the above-mentioned object, an optical disk according to the present invention includes a resin molded substrate and has a plurality of servo areas and a plurality of data areas alternately arranged in a circumferential direction of the disk. An optical disc, wherein the servo area includes a clock mark arranged along a virtual track center line, and wobble marks arranged in a meandering manner along the virtual track center line, and the thickness of the resin molded substrate is reduced. It is not more than 0.7 mm. In the optical disc of the present invention, since the thickness of the resin molded substrate is 0.7 mm or less, even if the sample servo tracking method having a large data area is used, mark shift and double transfer when forming the resin molded substrate, An optical disk with few ghosts can be obtained.

In the optical disk of the present invention, it is preferable that the resin molded substrate is a substrate formed by injection molding.

It is preferable that the optical disk of the present invention further includes a recording film made of a magnetic material formed above one main surface of the resin molded substrate. With the above configuration, an optical disk capable of magnetically recording an information signal can be obtained.

In the above optical disk of the present invention, the distance (track pitch) between adjacent virtual track center lines.
However, it is preferable that the wobble mark be smaller than twice the radial width. With the above configuration, the recording density can be improved.

In the optical disc of the present invention, it is preferable that the wobble mark has a meandering direction different for each adjacent virtual track center line. With the above configuration, it is possible to prevent interference of signals from adjacent tracks.

It is preferable that the optical disk of the present invention has an address mark sequence including a plurality of address marks, and that the address mark sequence is distributed over a plurality of servo areas.

In the optical disc of the present invention, a learning area for detecting warpage of the resin molded substrate is provided following all or a part of the plurality of servo areas, and the learning area includes a plurality of wobble areas. It is preferred to have a bullmark. With the above configuration, it is possible to suppress the influence of the warpage of the resin molded substrate caused by thinning the resin molded substrate.

In the optical disk of the present invention, it is preferable that the servo area has an index mark indicating the existence of the learning area.

It is preferable that the optical disc of the present invention further includes control information, and the control information is formed on an outer peripheral portion.

In the optical disk of the present invention, a dielectric thin film and a magnetic thin film are sequentially stacked from the resin molded substrate side between the resin molded substrate and the recording film, and the data area is When light is irradiated from the resin molded substrate side, it is preferable that the reflectance in the wavelength region of approximately two thirds of the recording / reproducing wavelength is lower than the reflectance in the wavelength region of the recording / reproducing wavelength. With the above configuration, a non-recordable area can be easily formed in the data area.

In the optical disc of the present invention, a control film made of a magnetic material is further provided between the magnetic thin film and the recording film, and the Curie temperature of the control film is determined by the Curie temperature of the magnetic film and the recording temperature. Preferably, it is lower than the Curie temperature of the membrane. With the above configuration, the signal recorded on the recording film can be easily reproduced with higher resolution.

In the optical disk of the present invention, the length of the recording mark recorded in the data area is at least 10% of the effective diameter of a light spot irradiated for reproducing data recorded in the data area. Is preferred. With the above configuration, data recorded in the data area can be accurately reproduced.

In the optical disk of the present invention, it is preferable that the resin molded substrate is made of a polycarbonate resin.

The method of manufacturing an optical disk according to the present invention is a method of manufacturing an optical disk including a resin molded substrate and using a sample servo tracking method. A step of forming the resin molded substrate having a thickness of 0.7 mm or less. In the optical disk manufacturing method of the present invention, the thickness is 0.7 m by injection molding.
Since a resin-molded substrate having a size of m or less is formed, it is possible to prevent the occurrence of mark shift, double transfer, and ghost when forming the resin-molded substrate.

In the method for manufacturing an optical disk according to the present invention,
Preferably, the stamper is made of nickel, and the resin is a polycarbonate resin.

[0026]

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

(Embodiment 1) In Embodiment 1, an example of an optical disk of the present invention will be described.

FIG. 1A is a plan view of the optical disc 10 according to the first embodiment, and FIG.
Referring to FIG. 1, an optical disk 10 includes a resin molded substrate 11.
And an enhancement film 12, a recording film 13, a heat insulating film 14, a reflection film 15, and a protective coat 16 which are laminated on a resin molded substrate 11 and made of a dielectric thin film.

The resin molded substrate 11 is made of, for example, a polycarbonate resin, a polyolefin resin, a methacryl resin, or the like, and can be formed by injection molding. The resin molded substrate 11 has a diameter of, for example, about 60 mm. Also,
The resin molded substrate 11 has a thickness of 0.7 mm or less. It is preferable that the resin molded substrate 11 has a thickness of 0.3 mm or more. 0.3 mm thick resin molded substrate 11
With the above, the warpage of the optical disk 10 can be reduced. That is, the thickness of the resin molded substrate 11 is particularly preferably 0.3 mm or more and 0.7 mm or less.

The enhancement film 12 is a film for adjusting the light reflectance to an appropriate value. The enhance film 12 is made of a dielectric thin film, and for example, a SiN thin film having a thickness of about 90 nm can be used.

The recording film 13 is a film for forming the data area 22 (see FIG. 2), and has a thickness of about 15 nm, for example.
TbFeCo perpendicular magnetization film can be used. The recording of the information signal on the recording film 13 can be performed by, for example, recording by a thermomagnetic effect or recording by magnetic field modulation recording.

The heat insulating film 14 is composed of the recording film 13 and the reflective film 15
For example, an SiN film having a thickness of about 10 nm can be used.

The reflection film 15 is a film that reflects light transmitted through the recording film 13, and is, for example, an Al film having a thickness of about 40 nm.
A Ti film can be used.

The protective coat 16 is a film for preventing the reflection film 15 from being damaged. For example, an ultraviolet curable resin having a thickness of about 10 μm can be used.

FIG. 2 is an enlarged schematic view of a main part of the optical disc 10 shown in FIG.
Shown in Referring to FIG. 2, optical disk 10 includes a plurality of servo areas 21 and a plurality of data areas 22 alternately arranged in the disk circumferential direction on at least one principal surface side of resin molded substrate 11. The optical disk 10 of the present invention performs tracking of an irradiated light spot by a sample servo tracking method. That is, the servo area 21
Are wobble marks 24 (first wobble marks) and wobble marks 25 (second wobble marks) arranged meandering along the virtual track center line 23, and clock marks arranged along the virtual track center line 23. 26, and a control mark 27 such as an address mark or a synchronization mark. These marks are formed on the resin molded substrate 11 as convex portions or concave portions.

The servo area 21 and the data area 22
It exists alternately in the circumferential direction of the disk, and the number is
The number is 1000 to 3000 for one track.

The radial widths of the wobble marks 24 and 25, the clock mark 26 and the control mark 27 are as follows:
The size is about one-half to three-quarters of the track pitch (the distance between the virtual track center lines 23 adjacent in the radial direction). For example, when the track pitch is about 0.7 μm, the width of each mark in the disk radial direction is about 0.5 μm.
m and the length can be 0.3 μm to 0.6 μm. The depth of each mark is from λ / (8 × n) to λ /
The depth may be a predetermined depth within a range of (4 × n) (where λ is the reading laser wavelength and n is the refractive index of the disk). For example, the depth may be about 90 nm.

The control mark 27 may include an address mark string composed of a plurality of address marks. In this case, the address mark strings are dispersedly arranged in the plurality of servo areas 21. In the case of a distributed address mark in which the address mark array is dispersedly arranged in the plurality of servo areas 21, mark shift, double transfer, and ghost are likely to occur when the resin molded substrate 11 is formed. Is effective.

When the optical disk 10 of the first embodiment is stored in an optical disk drive (not shown) for recording and reproducing information, light radiated from an optical pickup built in the optical disk drive uses an objective lens or the like. And irradiates the virtual track center line 23 of the optical disc 10 as a light spot. Then, the light spot is scanned along the virtual track center line 23 using an appropriate servo means.

The wobble marks 24 and 25 have different meandering directions for adjacent tracks in the radial direction of the disk. The distance (track pitch) between the adjacent virtual track center lines 23 is the wobble marks 24 and 2
5 is smaller than twice the width in the disk radial direction. When the track pitch is smaller than twice the radial width of the wobble marks 24 and 25 (for example, when the radial width of the wobble marks 24 and 25 is about 0.5 μm).
m and the track pitch is about 0.7 μm), it is necessary to change the meandering direction of the wobble marks 24 and 25 for each adjacent track. This is because if the track pitch is smaller than twice the width of the wobble marks 24 and 25 in the radial direction of the disk, and if the wobble marks meander in the same direction (see FIG. 11), the signal from the wobble marks of the adjacent tracks is reduced. This is because a problem of leaking occurs.

Resin molded substrate 11 having a thickness of 0.7 mm
Optical disk 10 of the first embodiment using
With respect to an optical disk using a conventional resin molded substrate having a thickness of 1 mm, the frequency of occurrence of transfer errors (mark shift, double transfer, ghost) when forming the resin molded substrate 11 was measured. FIG. 3 shows the measurement result of the optical disk 10 and FIG. 13 shows the measurement result of the conventional optical disk. As is apparent from FIG. 3, the transfer error of the optical disk 10 of the first embodiment was smaller than that of the conventional optical disk.

Further, as is apparent from FIG. 3, transfer errors occur more frequently in the inner and outer peripheral portions of the disk, and when the inner and outer peripheral portions are compared, the transfer error in the outer peripheral portion is larger. It turned out to be less. In the case of an optical disc, a position at which recording or reproduction is started is generally called a lead-in area. In the lead-in area, there are important information such as system information for recording and reproduction and an index table of recorded information. Control information is arranged. Therefore, in the optical disk 10, it is preferable that the control information is formed on the outer peripheral portion so that recording and reproduction are performed from the outer peripheral side to the inner peripheral side of the disk. By performing recording and reproduction from the outer peripheral side to the inner peripheral side of the disc, tracking control of the light spot is often started from the outer peripheral side where the transfer error is small, and the access performance is improved. Therefore, a highly reliable optical disk can be obtained by the above configuration.

In the optical disk of the first embodiment, by reducing the thickness of the resin molded substrate 11 of the optical disk, it is possible to obtain an optical disk with less occurrence of mark shift, double transfer and ghost. We examined the occurrence of transfer errors (mark shift and double transfer / ghost) by changing the thickness of the resin-molded substrate. However, when the thickness of the resin-molded substrate was 1.2 mm, a very severe transfer error occurred. , The servo area did not perform its function. When the thickness of the resin molded substrate was 0.8 mm, the frequency of occurrence of transfer errors was improved as compared with the case where the thickness was 1.2 mm, but the servo area still did not function sufficiently. On the other hand, when the thickness of the resin molded substrate was 0.6 mm, the servo region exhibited its function sufficiently and the signal quality was good.

In the first embodiment, a TbFeCo film is used as an example of the recording film 13.
Similar effects can be obtained by using an amorphous phase change film. For example, ZnS or GeN
GeSbTe, InSbT as the recording film 13
A film made of e, InGaSb, GeSnTe or AgSbTe can be used, a ZnS.SiO ₂ film can be used as the heat insulating film 14, and a film made of Au, Al, Ti, Ni or Cr alone or an alloy thereof can be used as the reflective film. .

In the optical disk 10 of the first embodiment, since the thickness of the resin molded substrate 11 is 0.7 mm or less, an optical disk using the sample servo tracking method, which has few mark shifts, double transfer, and ghost, can be used. can get.

Further, in the optical disk 10 of the first embodiment,
Since the sample servo tracking method is used, an optical disk having a sufficient data area can be obtained.

(Embodiment 2) In Embodiment 2, a method for manufacturing the optical disk 10 of the present invention will be described. Note that a duplicate description of the portions described in the first embodiment will be omitted.

In the method of manufacturing the optical disk 10 according to the second embodiment, first, after the resin molded substrate 11 is injection molded, the enhancement film 12, the recording film 13, the heat insulating film 14, the reflection film 15, the protective film A coat 16 is formed.

Enhancement film 12, recording film 13, heat insulation film 1
4 and the reflection film 15 can be formed by, for example, a sputtering method, a vacuum evaporation method, a CVD method, or the like. The protective coat 16 can be formed, for example, by applying an ultraviolet curable resin on the reflective film 15 and then irradiating ultraviolet rays to cure the resin.

Next, an example of a method for forming the resin molded substrate 11 will be described. First, an example of an injection molding apparatus for manufacturing the resin molded substrate 11 of the optical disc 10 of the present invention will be described.

FIG. 4 is a schematic sectional view showing an example of a main part of an injection molding apparatus 40 used in the manufacturing method according to the second embodiment.
Shown in

Referring to FIG. 4, injection molding apparatus 40 includes a stamper 41 for forming a mark on the surface of resin molded substrate 11, a fixed mirror plate 42 for mounting stamper 41, and a fixed mirror. A rear plate 43 for fixing the face plate 42 to the fixed mold body (not shown), an inner stamper retainer 44 for fixing the stamper 41 to the fixed mirror plate 42, and a sprue installed inside the inner stamper retainer 44. A bush 45, a movable mirror plate 46, a rear plate 47 for fixing the movable mirror plate 46 to a movable mold body (not shown), an outer stamper retainer 48, and installed inside the movable mirror plate 46. Movable bush 49, a punch cutter 50 installed inside the movable bush 49, an ejector pin 51 installed inside the punch cutter 50, and an inner stamper presser 4
4 and an air passage 52 provided between the sprue bush 45
, An air passage 53 provided between the movable mirror plate 46 and the movable bush 49, and an injection nozzle 54. The stamper 41, the movable mirror plate 46, and the outer stamper retainer 48 form a molding cavity 55 that is a space filled with a resin material. The injection molding device 40
The resin molding substrate 11 is formed by injecting a resin material into the molding cavity 55 through the gate 56.

The function of the injection molding device 40 will be described below.

The fixed-side mirror plate 42 is attached to a fixed mold body (not shown) via a rear plate 43, and is attached to a fixed plate of a mold clamping device (not shown) via the fixed mold body. I have.

The fixed side mirror plate 42 and the back plate 43 are arranged on the same axis as the molding cavity 55. And
Inside the fixed-side mirror plate 42 and the back plate 43, an inner stamper retainer 44 is provided at a position concentric with the molding cavity 55 so as to penetrate the fixed-side mirror plate 42 and the back plate 43.
And a sprue bush 45 are formed. Between the outer peripheral surface of the sprue bush 45 and the inner peripheral surface of the inner stamper retainer 44, there is formed an annular air passage 52 with minute clearance communicating with the molding cavity 55.

The air passage 52 is selectively connected to a vacuum suction device or an air pressure supply device (not shown) through a pipe (not shown) provided through a fixed mold body (not shown). It has become. As will be described later, when the movable mold body is opened from the fixed mold body after the resin molded substrate 11 is molded, air is sucked through the air passage 52. Further, when the resin molded substrate 11 is released from the stamper 41 after the mold is opened, predetermined compressed air is blown out from the air passage 52.

The sprue bush 45 has a double cylindrical structure provided with a cooling water passage. At the time of molding the resin molded substrate 11, the resin material injected from the injection nozzle 54 is guided to the molding cavity 55 through the sprue bush 45.

A movable mirror plate 46 forming a molding cavity 55 together with the stamper 41 is attached to a movable mold body (not shown) via a back plate 47, and the mold is clamped via the movable mold body. It is attached to a movable board (not shown) of the apparatus.

The molding cavity 5 of the movable mirror plate 46
An outer stamper retainer 48 is disposed on the outer peripheral portion on the fifth side. The stamper 41 is provided with an inner stamper retainer 44.
And the outer stamper retainer 48. The stamper 41 is made of, for example, nickel and has an uneven shape corresponding to a mark (such as a wobble mark or a clock mark) to be formed on the resin molded substrate 11. By injecting a resin material into the molding cavity 55 to form the resin molded substrate 11, the uneven shape of the stamper 41 is transferred to the resin molded substrate 11.

In the center of the movable side mirror plate 46 and the back plate 47, the movable side mirror plate 4
6 and the movable bush 4 so as to pass through the back plate 47.
9 are arranged.

An annular air passage 53 having minute clearance is formed between the outer peripheral surface of the movable bush 49 and the inner peripheral surface of the movable mirror plate 46. An air pressure supply device is connected to the air passage 53 via a pipe (not shown) provided through a movable mold body (not shown).
When the movable mirror plate 46 is opened from the fixed mirror plate 42, predetermined compressed air is blown to the molding cavity 55 through the air passage 53.

Inside the movable bush 49, a punch cutter 50 is disposed coaxially with the molding cavity 55 so as to penetrate the movable bush 49. The punch cutter 50 is arranged so as to be movable in the direction of the central axis of the movable bush 49. The punch cutter 50 has a double cylindrical structure provided with a cooling water passage. An ejector pin 51 is formed at the center of the punch cutter 50 so as to penetrate the punch cutter 50. Ejector pin 51
Are arranged so as to be movable in the central axis direction of the punch cutter 50.

A driving means (not shown) such as a double-acting cylinder is provided at the end of the punch cutter 50, and the punch cutter 50 is moved by a predetermined distance in the direction of the central axis by using this driving means. be able to. Punch cutter 5
When 0 is drawn in the opposite direction to the injection nozzle 54, an annular gate 56 is formed between the sprue bush 45 and the punch cutter 50. In addition, by projecting the punch cutter 50 in the direction of the sprue bush 45, a central hole of the resin molded substrate 11 molded in the molding cavity 55 can be punched.

The ejector pin 51 can also be moved a predetermined distance in the direction of the central axis by a predetermined driving means (not shown). By projecting the ejector pins 51 toward the sprue bush 45 after the mold is opened, the resin in the central portion punched from the resin molded substrate 11 can be separated.

Next, an example of a method for manufacturing the resin molded substrate 11 using the injection molding apparatus 40 will be described below.

First, as shown in FIG. 4, with the punch cutter 50 and the ejector pin 51 pulled into the movable mold body, the movable mold body is matched with the fixed mold body. Then, with the molds matched, the injection nozzle 54 of the injection device is brought into contact with the sprue bush 45,
The resin material is injected from the injection nozzle 54. The injected resin material is injected through a sprue bush 45 and a gate 56 into a molding cavity 55 formed between the stamper 41 and the movable mirror plate 46. Note that the distance between the stamper 41 and the movable mirror plate 46 is set so that the thickness of the formed resin molded substrate is 0.7 mm or less. Further, the distance between the stamper 41 and the movable mirror plate 46 is preferably set such that the thickness of the formed resin molded substrate is 0.3 mm or more.

After the filling of the resin material into the molding cavity 55 is completed and a predetermined cooling / solidification period has elapsed, the punch cutter 50 is protruded, so that the center of the resin molding substrate 11 molded in the molding cavity 55 is formed. Punch a hole.

After the center hole is punched out, the movable platen (not shown) of the mold clamping device is retracted, so that the movable die body is detached from the fixed die body. That is, a mold opening operation is performed.

At the same time as starting the mold opening operation or immediately before the mold opening operation, a predetermined compressed air is supplied from the air passage 52 to the molding cavity 55 side. At the same time, the molding cavity 55 is
Suction inside. The resin molded substrate 11 molded in the molding cavity 55 is separated from the stamper 41 by compressed air blown out from the air passage 52. On the other hand, the resin molded substrate 11 is adsorbed to the movable mirror plate 46 by suction of air through the air passage 53.

That is, when the movable mold main body is opened from the fixed mold main body, the resin molded substrate 11 formed in the molding cavity 55 is detached from the stamper 41,
It is held on the movable mirror plate 46. In addition, the resin molded substrate 1
The resin in the central hole punched portion punched from 1 remains on the movable mold body side.

After the mold opening operation is completed by moving the movable mold body from the fixed mold body by a predetermined distance, the ejector pin 51 is protruded to remove the resin in the central hole punched portion from the movable mold body.

Thereafter, the resin molded substrate 11 held on the movable mirror plate 46 is taken out by a predetermined take-out device. When the resin molded substrate 11 is taken out from the movable mirror plate 46, an air passage 53 is usually used to assist the detachment (mold release).
Is connected to an air pressure supply device to supply compressed air from the air passage 53. Through the above steps, the resin molded substrate 11 is formed.

When a resin molded substrate having a thickness of 1.2 mm (conventional resin molded substrate) is formed by the above steps,
A transfer error as shown in FIG. 13 occurred. As shown in FIG. 13, it has been found that in the conventional manufacturing method, a transfer error (mark shift, double transfer, ghost) tends to occur at the inner peripheral portion and the outer peripheral portion of the resin molded substrate. It is considered that such a transfer error occurs when the mold is opened and the resin molded substrate is released from the stamper 41 after molding the resin molded substrate. Such a transfer error is caused by the cooling rate of the resin (for example, polycarbonate resin) as the material of the resin molded substrate 11 (that is, the curing rate of the resin),
This is considered to be caused by the difference in the heat shrinkage between the stamper 41 and the resin molded substrate 11.

That is, the stamper 41 comes into contact with the resin molded substrate again at the time of release from the difference in thermal shrinkage between the stamper 41 and the resin molded substrate, and the ghost marks 3a, 4a and 5a are formed by the convex portions formed on the stamper 41. It is thought to be formed. Since the resin molded substrate 11 and the stamper 41 have different heat shrinkage ratios by about one digit (the heat shrinkage ratio of the polycarbonate resin is 6 × 10 ^{−5 to} 7 × 10 ⁻⁵ [cm /
cm / ° C.] and the heat shrinkage of nickel is 1.28 × 1
0 ⁻⁵ [cm / cm / ° C.]), it is considered that a force always acts on the contact surface between the stamper 41 and the resin molded substrate 11 in a direction to shift the contact surface. Therefore, the stamper 41 and the resin-molded substrate 1 are used, for example, when the mold is opened.
If the contact frictional force changes so that the contact frictional force of the stamper 41 becomes weaker, the displacement between the stamper 41 and the resin molded substrate 11 is likely to occur.

Here, when the mark groups and grooves are formed at high density on the entire surface of the stamper 41, the anchor effect is large, and the displacement between the stamper 41 and the resin molded substrate hardly occurs. Further, when the mark groups and grooves are formed at high density on the entire surface of the stamper 41, the contact area between the stamper 41 and the resin molded substrate is large, so that the heat transfer from the resin molded substrate to the stamper 41 is large. it is conceivable that. For this reason, the temperature drop of the resin when the mold is opened is large, and the hardness of the resin is also large, so that it is considered that a transfer error is unlikely to occur.

On the other hand, in the case of the optical disk 10 using the sample servo tracking method described in the first embodiment, since the area of the mark occupying the resin molded substrate 11 is small, the adhesion between the resin molded substrate 11 and the stamper 41 is weak. , Poor anchor effect.

Since the heat transfer from the resin molded substrate 11 to the stamper 41 is also poor, the temperature of the molded resin is not sufficiently lowered at the time of opening the mold, and the hardness of the molded resin is low. -Ghosts are likely to occur. As described above, in the injection molding, double transfer easily occurs at the inner peripheral portion and the outer peripheral portion of the resin molded substrate 11, but the molding cavity 55 in this portion is formed by combining some mold parts. However, it is expected that the heat transfer will be worse than in the middle peripheral region because there are many spaces that hinder the heat transfer. Therefore, poor heat transfer and a small temperature drop of the molding resin can be considered as one of the causes of the occurrence of double transfer between the inner and outer peripheral portions of the resin molded substrate 11.

As described in the second embodiment, when the thickness of the resin molded substrate 11 is reduced to 0.7 mm or less,
Even in the case of an optical disk using the sample servo tracking method in which the area occupied by the mark in the entire disk is small, it is possible to suppress the occurrence of mark shift, double transfer, and ghost. There are two possible reasons for this.

One reason is that since the thickness of the resin molded substrate 11 is small, the total heat capacity of the resin molded substrate 11 is reduced, and the molding resin after the molding resin is filled into the molding cavity 55 is reduced. The reason may be that the temperature drop rate increases, the resin temperature drops sufficiently, and the hardness of the resin increases. Another reason is that the displacement force acting between the stamper 41 and the resin molded substrate 11 caused by the difference in the thermal shrinkage between the stamper 41 and the resin molded substrate 11 becomes weaker because the resin molded substrate 11 becomes thinner. There may be a reason.

The occurrence of a transfer error (mark shift, double transfer, ghost) was examined by changing the thickness of the resin molded substrate to be formed. When the thickness of the resin molded substrate was 1.2 mm, the transfer error was considered. Occurred very intensely and the servo area did not perform its function. When the thickness of the resin molded substrate was 0.8 mm, the frequency of occurrence of transfer errors was improved as compared with the case where the thickness was 1.2 mm, but the servo area still did not function sufficiently. On the other hand, when the thickness of the resin molded substrate was 0.6 mm, the servo region exhibited its function sufficiently and the signal quality was good.

In the case of a distributed address mark in which the address mark strings are dispersedly arranged in the respective servo areas 21, the stamper 41 and the centralized arrangement in which the address mark strings are arranged in the specific servo area are compared. Resin molded board 1
1 has low adhesion, and the structure of the present invention is effective.

Embodiment 3 In Embodiment 3, another example of the optical disk of the present invention will be described. The optical disc according to the third embodiment differs from the optical disc 10 according to the first embodiment only in that it has a learning area and that an index mark is formed in the servo area 21. . The structure of the optical disc described in the third embodiment is the same as the structure shown in FIG. 1, and can be manufactured by the manufacturing method of the second embodiment. At this time, a stamper having an uneven shape corresponding to the optical disc of the third embodiment may be used as the stamper 41.

The resin molded substrate 1 of the optical disk according to the third embodiment
FIG. 5 schematically shows an enlarged view of a main part of FIG.

The optical disk of the third embodiment has a servo area 2
A learning area 51 is provided following all of 1a or a part of the servo area 21a. That is, the optical disc of the third embodiment includes the learning area 51 between the servo area 21a and the data area 22. The servo area 21a includes a wobble mark 24 (first wobble mark), a wobble mark 25 (second wobble mark), a clock mark 26, a control mark 27, and an index mark 50.

The index mark 50 is a mark for indicating the existence of the learning area 51, and is formed on the resin molded substrate 11 as a concave portion or a convex portion. By detecting the index mark 50, it can be recognized that the learning area 51 exists following the servo area 21a.

The learning area 51 is an area for detecting the warp of the resin molded substrate 11 (that is, the warp of the optical disk), and includes a wobble mark 52 (third wobble mark).
And the wobble mark 53 (the fourth wobble mark),
A wobble mark 54 (fifth wobble mark) and a wobble mark 55 (sixth wobble mark) are provided.
The wobble marks 52 to 55 are formed on the resin molded substrate 11 as concave portions or convex portions.

The wobble marks 52 and 53 are arranged offset from each other by an equal distance from the virtual track center line 23 in opposite directions. That is, the wobble marks 52 and 53 are meanderingly arranged along the virtual track center line 23 as a pair of wobble marks.
The wobble marks 54 and 55 are arranged to be shifted from each other by the same distance from the virtual track center line 23 in opposite directions. That is, the wobble mark 54
And 55 are meanderingly arranged along the virtual track center line 23 as a pair of wobble marks. Here, the distance between the wobble mark 52 and the wobble mark 53 in the disc radial direction is wider than the distance between the wobble mark 24 and the wobble mark 25. In addition, wobble mark 5
The distance between the wobble mark 55 and the wobble mark 55 in the disk radial direction is
The distance between the wobble mark 24 and the wobble mark 25 is narrower.

The lower part of FIG. 5 schematically shows a change in a detection signal when the light spot 56 emitted from the optical head onto the optical disk is tracked and moves on the wobble mark. FIG. 5 shows a change in the detection signal when the warp of the optical disk is small. Similarly, FIG. 6 shows a change in the detection signal when the warp of the optical disk is large.

As described in the first and second embodiments, even in the sample servo tracking type optical disk having a low mark density, by reducing the thickness of the resin molded substrate 11, it is possible to prevent the mark shift, the double transfer and the ghost. . However, as the thickness of the substrate decreases, the tendency of the substrate to warp increases. Several methods have been proposed to eliminate such warpage. For example, a method has been proposed in which a dedicated light source for measuring the warpage is prepared, the optical disk is irradiated with light, and the position and intensity of the reflected light are measured to detect the warpage (Japanese Patent Laid-Open No. 59-198538). Gazette and JP-A-2-193329). However, the above method requires a separate optical system other than for recording and playback,
There were problems in terms of cost and space saving. As a method of measuring warpage using a light source for recording and reproduction,
Japanese Patent Application Laid-Open Nos. Hei 1-57425 and Hei 7-57425 propose a method in which information is read from a specific track of a warped optical disk, and at the same time, information previously recorded in an adjacent track is read to determine the magnitude of the warp. −
No. 50026). However, in this method, it is necessary to provide the specific track and the adjacent track other than the recording / reproducing track, and there is a problem that the recording capacity is reduced.

On the other hand, the optical disk of the third embodiment detects the warpage of the disk using the wobble mark. The method will be described below.

As shown in FIG. 5, in the case of a disk having a small warp, a perfect circular light spot 56 is irradiated on the optical disk. Then, the tracking-controlled light spot 56 moves on the virtual track center line 23 so that the magnitudes of the detection signals (reflected light amounts) at the wobble marks 24 and 35 become equal. When the perfect circular light spot 56 moves on the virtual track center line 23,
The magnitudes of the detection signals at the wobble marks 52 and 53 are equal, and the magnitudes of the detection signals at the wobble marks 54 and 55 are equal.

On the other hand, when the optical disk has a large warp, the optical disk is irradiated with a light spot 56a whose light intensity distribution and shape are asymmetric. And FIG.
As shown in FIG.
“a” moves along the virtual track center line 23 so that the magnitudes of the detection signals (reflected light amounts) at the wobble marks 24 and 25 become equal. That is, in this case, since the light intensity distribution and the shape of the light spot 56a are asymmetric, the center of the light spot 56a moves a position slightly shifted from the virtual track center line 23. When the center of the light spot 56a passes through the wobble marks 52 to 55 with the center slightly shifted from the virtual track center line 23, the meandering distance (the meandering distance in the disk radial direction) of each wobble mark pair is different.
2 and the wobble mark 53 have different detection signal magnitudes. Similarly, the magnitude of the detection signal is different between the wobble mark 54 and the wobble mark 55. As described above, since the detection signal in the learning area 51 is different between the case where the optical disc has no warp and the case where there is the warp, the warp of the optical disc can be detected. Then, by adjusting the angle between the optical axis of the light spot and the optical disk so that the detection signals at the pair of wobble marks 52 and 53 and the pair of wobble marks 54 and 55 become substantially equal, the influence of the warp of the optical disk is reduced. Can be removed.

As a method of adjusting the angle between the optical axis of the light spot and the optical disk, for example, an optical pickup is installed on a cantilevered guide rail, and the opposite side of the guide rail is moved in a direction perpendicular to the optical disk surface. Then, a method of adjusting the tilt angle of the optical pickup with respect to the optical disk can be mentioned (see Japanese Patent Application Laid-Open No. 62-62439).

FIG. 7 shows another example of the case where the optical disk is warped. FIG. 7 shows an example in which the shape of the light spot becomes an asymmetric shape different from the light spot 56a shown in FIG. Referring to FIG. 7, tracking-controlled light spot 56b moves along virtual track center line 23 such that the detection signals (reflected light amounts) at wobble marks 24 and 25 have the same magnitude. That is, in this case, since the light spot 56b is asymmetric, the center of the light spot 56b moves a position slightly shifted from the virtual track center line 23. The center of the asymmetric light spot 56 is the virtual track center line 2
When passing through the wobble marks 52 to 55 slightly deviated from the wobble mark 52, as in the case of FIG.
And the wobble mark 53 have different detection signal magnitudes. Similarly, the magnitude of the detection signal is different between the wobble mark 54 and the wobble mark 55. As described above, by adjusting the angle between the optical axis of the light spot and the optical disk so that the detection signals at the pair of wobble marks 52 and 53 and the pair of wobble marks 54 and 45 are substantially equal, the warpage of the optical disk is adjusted. Can be suppressed.

The method of Embodiment 3 for preventing the influence of the warp of the optical disk by using the learning area 51 is the case where the magnetic recording is performed on the recording film by the magnetic field modulation recording (for example, see Japanese Patent Application Laid-Open No. H08-208,1992).
-227542) is particularly effective. That is, when magnetic recording is performed on a recording film by magnetic field modulation recording, a magnetic field is applied to an optical disk using a magnetic head. The magnetic head is attached to a component called a slider, and the slider is fixed to the optical disk. The position of the magnetic head is determined by pressing the magnetic head with the force. At this time, since the warp of the optical disc changes depending on the force pressing the slider, the method of suppressing the influence of the warp of the optical disc described in the third embodiment functions more effectively.

According to the optical disk of the third embodiment, the same effects as those of the optical disk of the first embodiment can be obtained. Further, in the optical disc according to the third embodiment, by using the learning area 51, the influence of the warp of the optical disc can be suppressed.

In the third embodiment, an example of adjusting the angle between the optical axis of the light spot and the optical disk has been described as a method of correcting the positional deviation of the light spot. However, other methods, for example, an offset is applied to the tracking correction. Alternatively, a method of shifting the position where the light spot travels, or a method of giving an offset to the focus correction and shifting the position where the light spot is focused may be used.

In the third embodiment, the case where the control mark 27 and the index mark 50 are each formed of a single mark has been described. However, these may be formed of a plurality of marks. Similarly, the wobble marks 52 to 55 in the learning area 51 are also examples, and other configurations may be used as long as the warp of the optical disc can be detected.

(Embodiment 4) In Embodiment 4, another example of the optical disc of the present invention will be described. The same parts as those in the above embodiment will not be described repeatedly.

FIG. 8A is a schematic plan view of the optical disc 10a according to the fourth embodiment, and FIG.

Referring to FIG. 8B, the optical disk 10a
Are a resin molded substrate 11, an enhancement film 12 made of a dielectric thin film laminated on the resin molded substrate 11, and a reproduction film 8.
1, a control film 82, a recording film 13, a protective film 83, and a protective coat 16. The resin molded substrate 11 is the same as that of the first embodiment.
This is the same as that described above. The resin molded substrate 11 has a thickness of about 0.6 mm and a diameter of about 60 mm, for example, and is made of polycarbonate. As the enhance film 12, for example, a SiN film having a thickness of 50 nm can be used. The recording film 13 has a thickness of, for example, 80 nm.
TbFeCo perpendicular magnetization film can be used. The Curie temperature of the recording film 13 is higher than the Curie temperature of the reproducing film 81, for example, about 300 ° C. Protective coat 16
For example, an ultraviolet curable resin having a thickness of 10 μm can be used.

The reproducing film 81 is a film for reproducing a magneto-optical signal by irradiating a light spot, and is made of a magnetic thin film. The reproducing film 81 has, for example, Gd having a thickness of 50 nm.
An FeCo magnetic film can be used. The Curie temperature of the reproducing film 81 is lower than the Curie temperature of the recording film 13,
For example, it is approximately 230 ° C.

The control film 82 has a predetermined temperature (for example, approximately 2 ° C.).
The magnetic domain information of the recording film 13 is read at a temperature of 30 ° C. or less.
1 is a film for eliminating the magnetic transfer between the recording film 13 and the reproducing film 81 at a temperature higher than a predetermined temperature (for example, approximately 230 ° C.) and facilitating the movement of the domain wall of the reproducing film 81. Consists of The control film 82 has, for example, a thickness of 10
nm TbFe film can be used. The Curie temperature of the control film 82 is lower than the Curie temperature of the reproducing film 81 and the Curie temperature of the recording film 13, for example, about 150 ° C.
It is.

The protective film 83 is a film for protecting the recording film 13, the reproducing film 81, the control film 82, and the like from water vapor, oxygen, and the like. For example, an SiN film having a thickness of 100 nm can be used.

FIG. 9 is a schematic enlarged view of a main part of the optical disk 10a. Referring to FIG.
Numeral 0a denotes a servo area 21 and a data area 2 which are alternately arranged in the disk circumferential direction, with one main surface of the resin molded substrate 11 being alligated.
2a. The servo area 21 is the same as that described in the first embodiment.

The data area 22a is an area where the recording mark 91 is recorded, and has a non-recordable area 92.

The recording mark 91 is magnetic data recorded in the data area 22a and reproduced. Non-recordable area 9
Reference numeral 2 denotes an area where a magnetic signal cannot be recorded.

FIG. 14 shows an example of a data area of a conventional optical disk having no non-recordable area 92. As shown in FIG. 14, in the data area 6 of the conventional optical disc without the non-recordable area 92, recording marks 7 on adjacent tracks are connected, and there is a problem that crosstalk occurs.

The optical disk 10a is, as shown in FIG.
A non-recordable area 92 is provided between the virtual track center lines 23 in the data area 22a. With such a configuration, the recording marks 91 are read separately from each other in the tracks, so that a read signal from an adjacent track that enters the end of the light spot can be prevented, and an optical disc with less crosstalk can be realized.

The non-recordable area 92 is formed by changing the magnetic properties of the reproducing film 81 between the non-recordable area 92 and other parts. That is, the non-recordable area 9
The reproducing film 81 is formed so that the magnetic spins are magnetized in a direction perpendicular to the film surface in the portions other than the region 2, and the magnetic spin of the reproducing film 81 is always parallel to the film surface in the non-recordable region 92. The reproduction film 81 is formed so as to face in a desired direction. As a result, the magnetic information signal of the recording mark 91 recorded as the direction of the perpendicular magnetization is not displayed in the non-recordable area 92.

More specifically, the non-recordable area 92 is formed by irradiating a laser having a large power exceeding the recording power to this part to partially age (increase) the magnetization of the reproduction film 81. . For example, tracking control may be performed using the wobble marks 24 and 25 to scan the light spot. It is considered that the width of the non-recordable area 92 is smaller than the track pitch, and its size is preferably about one third of the track pitch or less. In this case, in consideration of the tracking properties of the wobble marks 24 and 25, the wavelength of the laser forming the non-recordable area 92 is the laser wavelength used for recording and reproduction (for example, 780 nm in the case of the fourth embodiment).
A wavelength of about two thirds or less is suitable. For this reason, when the optical disk 10a is irradiated with light from the resin molded substrate 11, the reflectance in the wavelength region of approximately two thirds of the recording / reproducing wavelength is lower than the reflectance in the wavelength region of the recording / reproducing wavelength. Is preferred.

For the optical disc 10a of the fourth embodiment,
FIG. 10 shows an example of the wavelength dependence of the reflectance when light is irradiated from the resin molded substrate 11 side. In FIG. 10, the vertical axis indicates the reflectance, and the horizontal axis indicates the wavelength of the irradiated light. As shown in FIG. 10, the lower the reflectivity in the wavelength region (for example, 520 nm) of about two thirds of the recording / reproducing wavelength, the better the absorption of the laser light, and the more efficiently the laser light with low laser power.
Alternatively, the non-recordable area 92 can be formed in a short time with a large laser power.

Next, an example of the operation of recording and reproducing a data signal on the optical disk 10a will be described. The recording of the data signal is performed by using a focused laser beam (for example, using an optical pickup installed in an optical disk drive or the like).
(Wavelength: 780 nm) by scanning while irradiating the reproduction film 81 as a light spot through the resin molded substrate 11 and the enhancement film 12. At this time, the recording film 13 at a position corresponding to the reproducing film 81 irradiated with the light spot
The power and irradiation time of the laser light to be irradiated are adjusted so that the temperature of the laser beam becomes equal to or higher than the Curie temperature (about 300 ° C.). By applying an appropriate external magnetic field from a magnetic head installed in an optical disk drive or the like at the same time as irradiating the laser beam, recording is performed according to the magnetization direction of the recording film 13 according to the direction of the external magnetic field when the temperature drops.

On the other hand, reproduction is performed using laser light having a lower power than the laser light used for recording. At room temperature, the information recorded on the recording film 13 as the direction of magnetization is transferred to the control film 82 by magnetic exchange coupling, and the information of the control film 82 is transferred to the reproducing film 81. The light spot where the laser light is focused is irradiated on the reproducing film 81. At this time, the temperature near the center of the light spot is higher than the Curie temperature of the control film 82 and lower than the Curie temperature of the reproducing film 81. The power of the laser beam is adjusted so as to be as follows. In this case, since the magnetization of the control film 82 disappears, the magnetization of the reproduction film 81 is hardly affected by the magnetic coupling from the control film 82. Further, since the magnetic coupling between the reproduction film 81 and the non-recordable region 92 is not strong, the magnetization of the reproduction film 81 is relatively easy to move. Therefore, the direction of magnetization of the recording film 13 transferred to the reproducing film 81 via the control film 82 outside the vicinity of the center of the light spot is also reflected near the center of the light spot irradiated on the reproducing film 81 for reproduction. Is done. As described above, the information of the magnetization of the recording film 13 in the temperature region lower than the Curie temperature of the control film 82 is spread and transferred to the temperature region higher than the Curie temperature of the control film 82, and is transferred to the outer peripheral portion of the light spot. The corresponding information on the recording film 13 is reproduced on the reproduction film 81 while spreading over the entire light spot. Therefore, according to the configuration of the optical disk 10a, it is possible to read the recording mark 91 which is smaller than the size of the light spot.

In the optical disc 10a of the fourth embodiment,
When the effective diameter of the light spot is, for example, about 750 nm, the reading error starts increasing when the size of the recording mark 91 is shorter than 150 nm, and the reading error rapidly increases when the size of the recording mark 91 is shorter than 80 nm. Therefore, the length of the recording mark 91 is 10% or more of the effective diameter of the light spot, and 20% of the effective diameter of the light spot for more accurate reproduction.
% Or more.

According to the optical disc 10a of the fourth embodiment, the same effects as those of the optical disc of the first embodiment can be obtained.
Further, according to the optical disk 10a, the recording / reproduction of the recording mark 91 can be performed with high reliability.

In the fourth embodiment, the non-recordable area 92
Is shown only in the data area 22a, but the non-recordable area 92 may be formed in the servo area 21. Laser light of various wavelengths can be used as the laser light used for recording / reproducing by appropriately adjusting the wavelength dependence of the reflectance. Recording wavelength of 620 nm to 650 nm
, The formation wavelength of the non-recordable region 92 is
It can be 50 nm.

The non-recordable area 92 also has the effect of weakening the coupling force of the magnetic exchange coupling. By forming the non-recordable area 92, the magnetic domain wall energy is less changed when the magnetic domain wall is generated and the magnetic domain wall is moved, and reading is easy. There is also an effect that a proper reproduction film 81 can be obtained.

[0119]

As described above, in the optical disk of the present invention, since the thickness of the resin-molded substrate is 0.7 mm or less, in the optical disk using the sample servo tracking method, mark shift, double transfer, ghost, etc. An optical disk with less noise can be obtained.

Further, according to the optical disk manufacturing method of the present invention, since a resin molded substrate having a thickness of 0.7 mm or less is formed by injection molding, it is possible to prevent a transfer error of the concavo-convex shape of the stamper.

[Brief description of the drawings]

FIG. 1 shows an example (a) of an optical disc according to the present invention.
It is a schematic plan view and (b) a schematic sectional view.

FIG. 2 is a schematic enlarged view showing an example of a main part of the optical disc of the present invention.

FIG. 3 is a graph showing the frequency of occurrence of transfer errors for the optical disc of the present invention.

FIG. 4 is a schematic view showing an example of an injection molding apparatus for manufacturing the optical disc of the present invention.

FIG. 5 is a schematic diagram showing an example of a servo area, a learning area, and a detection signal in the optical disc of the present invention.

FIG. 6 is a schematic diagram showing another example of a servo area, a learning area, and a detection signal for the optical disc of the present invention.

FIG. 7 is a schematic diagram showing another example of a servo area, a learning area, and a detection signal in the optical disc of the present invention.

8A and 8B are a schematic plan view and a schematic cross-sectional view of another example of the optical disc of the present invention.

FIG. 9 is a schematic diagram showing another example of a servo area and a data area in the optical disc of the present invention.

FIG. 10 is a graph showing an example of the wavelength dependence of the reflectance of the optical disc of the present invention.

FIG. 11 is a schematic diagram showing an example of a servo area for a conventional optical disc.

FIG. 12 is a schematic diagram showing a state of double transfer of a conventional optical disc.

FIG. 13 is a graph showing the frequency of occurrence of transfer errors in a conventional optical disc.

FIG. 14 is a schematic diagram showing an example of a data area of a conventional optical disc.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Resin molding board 12 Enhancement film 13 Recording film 14 Heat insulation film 15 Reflection film 16 Protective coat 21, 21a Servo area 22, 22a Data area 23 Virtual track center line 24, 25, 52, 53, 54, 55 Wobble mark 26 Clock mark 27 Control Mark 40 Injection Molding Device 41 Stamper 50 Index Mark 51 Learning Area 56, 56a, 56b Light Spot 81 Reproduction Film 82 Control Film 83 Protective Film 91 Recording Mark 92 Non-Recordable Area

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Motoyoshi Murakami 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5D029 JB04 JB18 JC02 KA07 KA15 KB14 LA05 LB02 MA13 5D090 AA01 BB10 CC14 DD03 DD05 FF03 GG03 GG27 HH01 HH08 KK03 5D121 AA01 AA02 DD05 EE13

Claims (15)

[Claims] 1. An optical disc including a resin molded substrate and having a plurality of servo areas and a plurality of data areas alternately arranged in a circumferential direction of the disc, wherein the servo areas are arranged along a virtual track center line. An optical disk, comprising: a clock mark formed thereon; and wobble marks arranged in a meandering manner along the virtual track center line, wherein the thickness of the resin molded substrate is 0.7 mm or less. 2. The optical disk according to claim 1, wherein the resin molded substrate is a substrate formed by injection molding. 3. A recording film comprising a magnetic material formed above one main surface of the resin molded substrate.
Or the optical disc according to 2. 4. The optical disc according to claim 3, wherein a distance between adjacent virtual track center lines is smaller than twice a radial width of the wobble mark. 5. The wobble mark has a meandering direction different for each adjacent virtual track center line.
An optical disk according to claim 1. 6. The optical disc according to claim 3, further comprising an address mark sequence including a plurality of address marks, wherein the address mark sequence is distributed over a plurality of servo areas. 7. A learning area for detecting warpage of the resin-molded substrate following all or a part of the plurality of servo areas, wherein the learning area includes a plurality of wobble marks. 4. The optical disc according to 3. 8. The optical disk according to claim 7, wherein the servo area includes an index mark indicating the existence of the learning area. 9. The optical disk according to claim 3, further comprising control information, wherein the control information is formed on an outer peripheral portion. 10. A semiconductor device comprising: a dielectric thin film and a magnetic thin film sequentially laminated from the resin molded substrate side between the resin molded substrate and the recording film; and the data area is arranged from the resin molded substrate side. 4. The optical disk according to claim 3, wherein, when irradiated with light, the reflectance in a wavelength region of approximately two thirds of the recording / reproducing wavelength is lower than the reflectance in a wavelength region of the recording / reproducing wavelength. 11. A control film comprising a magnetic material between the magnetic thin film and the recording film, wherein the Curie temperature of the control film is higher than the Curie temperature of the magnetic film and the Curie temperature of the recording film. 11. The optical disk according to claim 10, wherein the optical disk is also low. 12. The recording mark according to claim 3, wherein a length of the recording mark recorded in the data area is 10% or more of an effective diameter of a light spot irradiated for reproducing data recorded in the data area. Optical disk. 13. The optical disk according to claim 3, wherein said resin molded substrate is made of a polycarbonate resin. 14. A method of manufacturing an optical disk including a resin molded substrate and using a sample servo tracking method, wherein a resin having a thickness of 0.7 mm or less is injected into a molding cavity provided with a stamper having an uneven shape. A method for manufacturing an optical disk, comprising a step of forming the resin molded substrate. 15. The method according to claim 14, wherein the stamper is made of nickel, and the resin is a polycarbonate resin.