JP3741021B2 - Optical disc and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc that needs to be annealed by a light beam and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, optical discs have been actively applied to AV (audio / visual). For example, in DVD (Digital Versatile Disc) mainly for movie content, write-once and rewritable formats such as DVD-R, DVD-RAM, and DVD-RW have been developed and are becoming popular as next-generation recorders for VTRs. . With the spread of BS digital broadcasting and broadband communications in the future, the appearance of large-capacity optical disc formats capable of recording compressed images with higher image quality, and the appearance of high-density optical disc formats that are smaller, portable, and have high network compatibility with the same capacity. Be expected. As an example for realizing such high-density recording, a DWDD (Domain Wall Displacement Detection) type optical disc, which is a kind of super-resolution type, has been proposed. In the DWDD type optical disc, it is necessary to weaken the magnetic coupling between adjacent recording tracks (reduction of magnetic anisotropy). For this reason, when manufacturing an optical disk of the DWDD system, initialization (hereinafter referred to as annealing, annealing method or annealing process) for weakening the magnetic coupling between adjacent recording tracks is performed before recording the information signal. Do.
[0003]
Japanese Patent Application No. 2001-120688 discloses an optimum setting method of annealing power in the above annealing method. In this conventional example, in order to determine the optimum power for annealing, a method for determining the optimum power for annealing by irradiating the test annealing power to the power test area provided on the optical disk and measuring the reflectivity, and the test A method for determining the optimum power by measuring the reflectance during annealing power irradiation is shown.
[0004]
[Problems to be solved by the invention]
However, in the method for determining the annealing power as described above, it has been found that since the change in reflectance with respect to the annealing power is small depending on the configuration of the recording film, the determined optimum power varies and the reproducibility may be poor. Therefore, this method is not sufficient for a usage that aims at higher density and consequently the annealing power margin becomes narrower, and a more accurate annealing power learning method is required. For this purpose, the same recording / reproduction as in actual practice is performed to check whether recording / reproduction is possible, or by measuring the jitter and error rate to determine whether annealing is optimal (referred to as normal recording / reproduction inspection). Implementation is considered best.
[0005]
By the way, since annealing is performed in the disc manufacturing process, it may be difficult to perform normal recording / playback inspection at that time. In the example of the DWDD optical disc, it is desirable that the annealing be performed with the light spot being most focused. Annealing from the light input surface side (over the substrate) for normal recording / reproduction is not practical because a lens with a high NA cannot be used due to the influence of substrate thickness unevenness or aberration due to tilt. Since the DWDD optical disk has a single-sided specification, if annealing is performed from the recording film-attached side (film surface), the light spot is not affected by the aberrations, so that a short wavelength (blue) light beam can be reduced with a high NA lens. . However, in this case as well, it is desirable to anneal from the film surface before applying the protective coating that affects the aberration. As described above, annealing is preferably performed from the film surface without the protective coating, but if the magnetic head is used without the protective coating, the recording surface will be damaged. Cannot be implemented at the stage. Even if normal recording / playback inspection can be performed using a flying magnetic head or the like, the recording / playback sensitivity slightly shifts when a protective coat is applied, so that correction is required for calculating the optimum annealing power.
[0006]
In order to perform the normal recording / reproduction inspection, it is desirable that the optical disk is a completed form in which a protective coat or the like is finished and the cartridge is contained. If it is in this form, this mass production drive device corresponding to the optical disk can be used and is economical. In the mass production drive device, the magnetic head and the optical head can be easily positioned at predetermined positions with respect to the optical disk due to the relationship between the loading mechanism and the cartridge.
[0007]
On the other hand, consider the possibility of annealing in the cartridge. First, it is necessary to overcome the aberration problem of the protective coat and enable annealing over the protective coat. Then, it is necessary to make the annealing optical head enter the cartridge opening from the magnetic head side so that the entire area of the optical disk can be accessed. To that end, it is necessary to develop a new mechanism dedicated to annealing, including loading, by placing an annealing optical head for a manufacturing apparatus using a blue laser in a size smaller than an optical head optimized for mass production. Even with such a development requiring a large investment, it is practically difficult to arrange the magnetic head and the annealing optical head on the same side in the opening of the cartridge. In other words, since annealing and the normal recording / reproducing inspection cannot be performed by the same apparatus, it is considered that there is no merit of annealing the optical disk contained in the cartridge.
[0008]
As described above, at present, there is a problem that the annealing process and the inspection process for determining the optimum annealing power with high accuracy cannot be performed in one place, and there is no effective means for determining the optimum annealing power. In order to solve this problem, the present invention provides an optical disc annealed with an optimal annealing power, and an optical disc manufacturing method.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an optical disc of the present invention is an optical disc in which both sides of a recording / reproducing track for recording / reproducing data are annealed with a light beam of a predetermined power for finding the optimum power of the annealing. A plurality of test tracks and an ID track for recording / reproducing an identification number (ID) of an annealing apparatus for performing the annealing are provided.
[0010]
According to the optical disk of the present invention, before and after annealing the recording / reproducing track of the annealing apparatus, for the test for inspecting in the downstream inspection process whether the annealing power is appropriate or how much it is shifted from the appropriate value. A track can be created. In addition, since the ID of the annealing apparatus can be recorded on the ID track at the same time, even when annealing is performed with a plurality of annealing apparatuses, the annealing apparatus can be specified in the downstream inspection process, and the annealing power is shifted, Without a doubt, the annealing power of the target annealing device can be corrected to an appropriate value (optimal annealing power).
[0011]
In the optical disc of the present invention, each bit recording of the ID of the ID track is performed by recording whether or not a plurality of sections having a predetermined length or more are annealed with the predetermined annealing power or higher annealing power. The reproduction of the ID is performed by previously recording data of a predetermined pattern on the entire ID track, and after the recording, depending on presence / absence or large / small of the data for each section on the ID track. It is preferable that the reproduction method regenerates each bit of the ID by discriminating whether there is no annealing or not. According to this preferred example, the ID recording can be performed by using the annealing function of the annealing device, and the ID reproduction can be performed by simply detecting the presence or absence of a signal in normal recording / reproducing and implementing a simple function that is adopted by a microcomputer. realizable.
[0012]
In the optical disc of the present invention, number information based on a predetermined rule is recorded on the ID track in addition to ID, and the ID and / or the number information is recorded and reproduced on a pre-recording / retrack. It is preferably used as a media ID. According to this preferred example, media ID information that can be used for copyright protection or the like can be embedded in the target optical disk without introducing a new separate process.
[0013]
Furthermore, in order to achieve the above object, an optical disc manufacturing method of the present invention is an optical disc in which both sides of a recording / reproducing track for recording / reproducing data are annealed with a light beam having a predetermined power, and an optimum power for the annealing is obtained. An optical disc manufacturing method comprising a plurality of test tracks for finding out and an ID track for recording / reproducing an identification number (ID) of an annealing apparatus for performing the annealing, wherein both sides of the pre-recording re-track are provided A first step of annealing at a set power corresponding to the predetermined power; and a second step of creating an anneal inspection track in which the test track is annealed at a plurality of different powers centered on the set power. An annealing process for annealing the optical disk using an annealing apparatus, and an annealed recording / playback track A third step of writing / verifying a part or all of the disk to determine the quality of the pre-recording re-track, and a fourth step of writing / verifying the annealing inspection track to find the optimum annealing power of the annealing apparatus. And an annealing power adjustment step of changing the set power to the optimum annealing power found in the inspection process.
[0014]
According to the optical disk manufacturing method of the present invention, the test track created in the annealing process can be actually recorded and reproduced in the optical disk inspection process to accurately determine whether the annealing power is appropriate, and the annealing power of the annealing apparatus is shifted. In such a case, the optical disk can be readjusted to the optimum annealing power, so that an optical disc annealed with the optimum annealing power is always obtained.
[0015]
In the method of manufacturing an optical disc according to the present invention, the annealing step includes a plurality of annealing apparatuses to which IDs are assigned, and each annealing apparatus includes a fifth step of recording each ID on the ID track, The optical disc inspection apparatus in the inspection step includes a sixth step of reading the ID from the ID track, and changes the set power to the optimum annealing power for each annealing apparatus specified by the ID from the plurality of annealing apparatuses. It is preferable. According to this preferred example, even when the annealing step is constituted by a plurality of annealing apparatuses, it is possible to specify the annealing apparatus and to readjust the optimum annealing power without fail.
[0016]
In the optical disk manufacturing method of the present invention, each bit recording of the ID track ID in the fifth step may be performed with a plurality of sections having a predetermined length or more with the predetermined annealing power or higher annealing power. In the recording method, recording is performed by annealing or not, and the reproduction of the ID is performed by previously recording data of a predetermined pattern on the entire ID track, and after the recording, data of each section on the ID track is recorded. It is preferable that the reproduction method reproduces each bit of the ID by discriminating whether there is no annealing or not depending on presence / absence or large / small. According to this preferred example, according to this preferred example, the ID recording may be performed by using the annealing function of the annealing apparatus, and the reproduction of the ID can be performed simply by detecting the presence / absence of a signal in normal recording / reproduction and adopting it by a microcomputer. This can be achieved simply by implementing various functions.
[0017]
In the optical disk manufacturing method of the present invention, it is preferable that the fifth step records number information based on a predetermined rule in addition to the ID as the media ID on the ID track. According to this preferred example, media ID information that can be used for copyright protection or the like can be embedded in the target optical disk without introducing a new separate process.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an overall view of an optical disc 100 according to an embodiment and uses of each track. In FIG. 1, an optical disk 100 is a sample servo type magneto-optical disk, 101 is composed of a plurality of tracks, and is a data area (recording / reproducing track) for actually recording / reproducing data such as user data and management information, It is necessary to include a test area for driving, and to record / reproduce all the recording / reproducing tracks 101 in this area by annealing. Each track is composed of a plurality of segments 102. The number of segments 102 per track is, for example, 1280, which is sufficient for tracking servo. The segment 102 includes a pit area 103 for recording sample servo signals and address signals, and a groove area 104 for recording and reproducing data. A lead-in area 105 and a lead-out area 106 are arranged on the inner and outer circumferences of the optical disc, respectively. Other than the groove area of the control track 105a, which will be described later, the segment 102 is formed in the same manner as the data area 101.
[0019]
The track configuration of each area is shown on the right side of FIG. That is, the lead-in area 105 is a test track consisting of a control track 105a in which information on how to use the disc is recorded in advance from the inner periphery, and a plurality of tracks for testing the annealing power (equivalent to power learning of normal data). It consists of three areas: an ID track 105c for recording ID information such as an ID for the annealing track 105b and an annealing apparatus ID. In the groove area 104 in the segment 102 of the control track 105a, a part of the groove is composed of prepits (also called embosses). The lead-out area 106 includes an ID track 106a and a test track 106b. Even one ID track 105c and 106a functions sufficiently.
[0020]
FIG. 2 is a diagram showing a structure when the optical disc 100 is of the DWDD playback system, and is a perspective view (2a) showing a partial cross section of the data area 101 and an enlarged view (2b) of the cross section. In FIG. 2 (2a), 201 is a substrate of the optical disc 100, which is formed by injection molding of polycarbonate or the like, and has a thickness of about 0.4 mm to 1.2 mm, for example. The track pitch is set to be as small as 0.7 μm or less for high density. Reference numerals 202 and 203 denote a groove and a land constituting the groove area 104, respectively. Reference numerals 204, 205, 206, and 213 denote a first wobble pit, a second wobble pit, an address pit, and a mirror part that constitute the pit area 103, respectively. Reference numeral 207 denotes a first dielectric layer, 208 denotes a magnetic layer, and 209 denotes a second dielectric layer, which are formed in this order on the substrate, and constitute the laminated thin film 200 as a whole. For the first dielectric layer 207 and the second dielectric layer 209, for example, Si _Three N _Four , AlN, SiO ₂ , SiO, ZnS, MgF ₂ And transparent dielectric materials such as these composite materials can be used.
[0021]
Reference numeral 210 denotes a magnetic coupling cutoff area, which separates the tracks of the optical disc 100 and prevents adverse effects from adjacent tracks during DWDD playback. For the formation of the magnetic coupling blocking region 210, an annealing apparatus described later is used in the manufacturing process of the optical disc 100. A high-power annealing light beam (light spot) 212 obtained by narrowing the laser beam with the objective lens 211 that is a part of the annealing apparatus is applied to the land 203 and the laminated thin film 200 on the extension line thereof, thereby providing magnetic characteristics. It is formed by degrading. In actual disc manufacturing, it is necessary to anneal all sides of a track on which normal recording / reproduction is performed, including the data area 101, for each optical disc. Specifically, the annealing can be realized by scanning the land of the region to be annealed with a predetermined annealing power while tracking. In this case, in order to reduce the manufacturing cost, it is required that the scanning speed be as fast as possible and realized in a short time.
[0022]
The width of the magnetic coupling blocking region 210 is preferably as small as possible in order to increase the density by narrowing the track pitch. One of the reasons why it is necessary to reduce the thickness is that the laminated thin film 200 can be locally deteriorated by increasing the energy density of the annealing light beam 212, and the scanning speed, that is, the linear speed can be increased even with the same power. Another reason is that a push-pull signal is detected from a land of a track having a smaller track pitch and tracking is performed. In order to make the diameter of the annealing light beam 212 as small as possible, a short laser light source having a wavelength λ of about 400 nm, such as a GaN semiconductor laser element or a SHG element that halves the wavelength of a red laser, is used here. Is set to 0.65 to 0.85 larger than usual, thereby narrowing down the annealing light beam determined by λ / NA.
[0023]
Further, when an objective lens having a short wavelength or high NA is used, an attempt is made to form a light beam on the laminated thin film 200 through the substrate 201 as in normal recording / reproduction (laser light is incident from the lower side of the figure). As a result, the aperture performance of the light beam is significantly degraded with respect to the tilt of the substrate as compared with a normal light beam, which is not a preferable method. Paradoxically, if a stable light beam is to be formed through the substrate, it is difficult to shorten the wavelength of the laser light source and to increase the NA of the objective lens.
[0024]
Therefore, here, in the annealing process, laser light is incident from the laminated thin film 200 side. In this way, since the influence of the substrate tilt can be removed, a small and good annealing light beam can be formed on the laminated thin film 200 by shortening the wavelength of the laser light source and increasing the NA of the objective lens. For example, the size of the annealing light beam 212 with λ = 405 nm and NA = 0.85 is about 0.44 times smaller than the light beam with the wavelength λ = 650 nm and NA = 0.6 used for normal recording / reproduction. it can.
[0025]
When the disk is viewed from the side of the laminated thin film 200, the land 203 looks forward, so it looks like a normal reproduction groove, so attention should be paid to the tracking polarity. Usually, this type of optical disc is coated with a protective coat of about several μm by spin coating after film formation. However, when this protective coat is present, the focus S-shape interferes and the accuracy of focusing on the film surface is reduced. Annealing is preferably performed without annealing since problems such as the occurrence of aberration of the objective lens due to uneven thickness of the protective coating and the influence of tilt due to the thickness of the protective coating cannot be ignored. However, the annealing process must be performed in a clean environment in order to avoid coating unevenness and defects due to dust during the protective coating.
[0026]
The land 203 is arranged mainly for realizing annealing in addition to the thermal separation effect between the tracks. In addition to the land 203, a first wobble pit 204 and a second wobble pit 205 are provided for normal recording and reproduction. Sample servo is applied so that the wobble signals have the same magnitude so that the reproduction light beam can scan the center of the groove 202. The wobble pits are devised so that the pits are alternately arranged on the odd and even tracks so that the recording / reproducing beam is tracked even when the diameter of the annealing light beam 212 is twice.
[0027]
Next, the configuration of the magnetic layer 208 will be described. In FIG. 2 (2 b), 21, 22, and 23 are a domain wall motion layer, a blocking layer, and a recording layer, respectively, and are formed on the first dielectric layer 207 in this order to constitute the magnetic layer 208.
[0028]
The thickness of the second dielectric layer 209 is set such that when the laser beam for annealing is irradiated from the second dielectric layer 209 side, the reflectance is low and the light is efficiently absorbed. Specifically, the thickness of the second dielectric layer 209 is preferably around λ / (4 × n), and λ / (12 × n) or more and λ / (2 × n) or less (preferably λ / (6 × n) or more and λ / (2 × n) or less).
[0029]
The magnetic layer 208 includes three or more magnetic layers so that reproduction can be performed by the DWDD method. The magnetic layer 208 is a layer annealed using light having a wavelength λ incident from the second dielectric layer 209 side. As an example of the magnetic layer 208, when the magnetic layer 208 includes the domain wall motion layer 21, the blocking layer 22, and the recording layer 23 that are sequentially stacked from the substrate 201 side, the following materials may be used as the material of each layer. it can. The material of the domain wall moving layer 21 is a material having a small domain wall coercive force and a small saturation magnetization in the temperature range near the Curie temperature of the blocking layer 22, which has a Curie temperature lower than that of the recording layer 23 and higher than that of the blocking layer 22. High materials can be used. For example, GdCo, GdFeCo, or an alloy thereof having a Curie temperature of about 220 ° C. to 260 ° C. can be used.
[0030]
As the material of the blocking layer 22, it is preferable to use a material having a Curie temperature lower than that of the domain wall moving layer 21 and the recording layer 23 and having a large domain wall coercive force just below the Curie temperature. For example, DyFe, TbFe, or an alloy thereof can be used, and a typical Curie temperature of 140 ° C. to 180 ° C. can be used.
[0031]
The recording layer 23 has a large domain wall coercive force, a Curie temperature higher than that of the domain wall moving layer 21 and the blocking layer 22, and a material having a small saturation magnetization in a temperature range near the Curie temperature of the blocking layer 22 can be used. . For example, TbFeCo or an alloy thereof having a Curie temperature of 280 ° C. to 300 ° C. can be used.
[0032]
FIG. 3 is a diagram illustrating the manufacturing process (3a) and the manufacturing procedure (3b) of the optical disc 100 described above, focusing on annealing. In the following description, for convenience of explanation, it is assumed that 106b of 105b and 106b is used as a test track and 106a of 105c and 106a is used as an ID track. In some cases, both are used to improve reliability.
[0033]
In the manufacturing process (3a), first, in the forming and film forming process of S301, the optical disk substrate is formed by injection molding, and the magnetic layer 208 and the like are formed on the substrate by sputtering. Thereafter, annealing is performed (S302: annealing process). The annealed optical disc 100 is coated with a protective coat and a lubricant, and a clamping plate for magnets and clamps is welded and placed in a cartridge (S303: protective coat / assembly process). The optical disk 100 stored in the cartridge is used for inspection and setting of the recording / reproduction test and the format of physical, logical, application, etc. for the non-defective optical disk in addition to the test related to the quality determination of annealing in the optical disk inspection step S304. Corresponding processing is performed. Here, the optical disc 100 which has become a non-defective product and completed is shipped to the market through a packing / shipping step S305.
[0034]
The annealing step S302 and the optical disc inspection step S304 take more time per sheet than the other steps. Therefore, in order to adjust the process time, a plurality of annealing devices and a plurality of optical disc inspection devices are arranged respectively. use. A plurality of arrows in FIG. As will be described later, in the optical disc inspection step S304, since the difference between the set annealing power and the optimum annealing power for each annealing apparatus can be measured, the annealing power of each annealing apparatus is optimally corrected based on the difference (S306: annealing power adjustment). ).
[0035]
It should be noted that there is a possibility that a malfunction may occur if the annealing power correction is performed for each optical disk due to sensitivity variation of the optical disk 100 or mixing of defects. Therefore, it is preferable to perform statistical processing such as averaging and periodically feed back to the annealing apparatus. . However, if the annealing is incomplete and recording / reproduction is poor, the target annealing apparatus is immediately stopped and the apparatus is replaced or repaired. Since the above operations are not efficient and manual errors may occur, it is preferable to introduce automation using a computer.
[0036]
Specific configuration examples of the annealing apparatus and the optical disk inspection apparatus will be described later with reference to FIGS. 6 and 7, respectively. The operation procedures (steps) are as shown in FIGS. 3 (3b1) and (3b2).
[0037]
That is, in the operation procedure of the annealing apparatus (3b1), the normal recording / reproducing groove 202 is activated while being tracked with the reproduction power, and the address is read to seek to at least one track before the data area 101. The half jump is performed to change the tracking polarity to cancel the still jump, the power is increased to the annealing setting power, the land 203 arranged in the spiral is continuously scanned, and both sides of the whole recording / playback track 101 are all scanned. Annealing is performed (S307). When the annealing is finished, the power is once returned to the reproduction power, tracked to the groove 202, and a standby state in which the address can be read is set.
[0038]
Next, the test track 106b is seeked to be used as a test track for annealing power, and the test track 106b annealed with different annealing power around the set power is created (S308). For the test track 106b, for example, the set power is 5 mW, and 13 types of 106b are created in increments of 0.25 mW from 3.5 mW to 6.5 mW. The production of the test track 106b can be realized by performing an operation that terminates the annealing operation with five lines for each power, or performing an operation of sequentially increasing the annealing power during the annealing operation.
[0039]
First, it returns to the standby state, and finally seeks to the ID track 106a to record the ID (S309). The tracking polarity at this time is basically the groove 202. The recording power of the ID is set annealing power or higher than that, and the section of the target groove is surely deteriorated. For simplification, both ends of the ID track 106a may be annealed with high power without changing the tracking polarity at the time of annealing, and the groove characteristics may be deteriorated. However, it is preferable because adjacent tracks are also deteriorated. It's not a method.
[0040]
Next, the operation procedure of the optical disk inspection apparatus (3b2) will be described. The optical disc 100 to be inspected is already in the cartridge. For an optical disk inspection apparatus, it is economically appropriate to use an ordinary drive device for mass production having normal recording and reproduction. The description of the operation here shows only those related to the quality determination of annealing, and the description of the contents related to the formatting operation as described above and other shipping inspections is omitted.
[0041]
After the optical disk is started, the optical disk inspection apparatus writes / verifies (W / V) the annealed recording / playback track 101 at a rate of, for example, 1 out of 16 tracks, and determines the quality of these tracks (S310). If a predetermined level of failure occurs at this stage, the optical disk to be inspected is determined to be defective. In order to determine whether this failure is due to annealing, the following steps are performed even if the failure is detected.
[0042]
Next, W / V is applied to the test track 106b for each set value of the annealing power created by the annealing apparatus, the upper and lower annealing powers that are NG at W / V are found, and the average power is calculated as the optimum annealing power. (S311). In this optimal power calculation step, instead of using normal GO / NOGO W / V to detect more accurate power, jitter measurement and error rate measurement are performed, and playback parameters that are more sensitive to annealing power fluctuations are changed. Thus, the optimum annealing power can be accurately found by performing the inspection of the reproduction characteristics. When the difference between the upper limit and the lower limit power found here falls below a predetermined value, it is determined as NG. Further, when a defect is found in the test track 106b, processing is performed so as to exclude it from the optimum power calculation.
[0043]
Finally, seek to the ID track 106a, read the ID information (details will be described later), specify which annealing apparatus the optical disc 100 just inspected is annealed, and use it in the annealing power adjustment S306.
[0044]
If a track jump or the like occurs during annealing and the annealing is interrupted, the annealing is retried from the point of interruption, and if the track jump still occurs, the annealing is skipped. However, the length of the track to be skipped must be limited to a level that does not affect subsequent normal recording / playback. During annealing, it is also effective to inspect the pit quality of the land 203 and the pit area 103 and feed back to the upstream molding / film forming step S301. Of course, it is also important not to create a defective optical disc by detecting a failure or failure of the annealing apparatus itself.
[0045]
FIG. 4 is a diagram for explaining a specific method of ID recording and reproduction described above. First, the record of the device ID is shown in (4a). Recording is performed by allocating ID information bits to a section obtained by dividing the ID track 106a into a predetermined length or more. Here, for simplicity, one of the segments 102 is defined as one section. In the recording of ID information, “power equal to or higher than the set annealing power” and “reproduction power level” are applied to each segment 102 in accordance with “1” and “0” of the bits.
[0046]
The part irradiated with the set annealing power or more deteriorates its magnetic characteristics as in the case of annealing. The degree of deterioration is detected by the following reproduction process. (4b) shows pattern recording before reproduction. The seek is performed on the ID track 106a, the laser intensity is set to the recording level, the magnetic head is magnetically modulated, and the recording is equivalently performed on the ID track 106a. The data pattern here is a single frequency signal. Since the recording can be performed for each segment and the low frequency capable of normal MO reproduction is sufficient instead of the high frequency that requires super-resolution reproduction, there are few mounting problems. Next, the ID track 106a prepared here is reproduced (4c). With the presence or absence of deterioration of the magnetic characteristics of the segment 102, the reproduction amplitude of the MO becomes small / large, respectively, which can be detected as an envelope and reproduced as bits “1” / “0”, respectively.
[0047]
In the above embodiment, one segment is assigned to one bit. However, since one track has as many as 1280 segments, for example, 128 bits of ID information may be inserted or 8 segments or more may be assigned to one bit. In addition, when 1 bit is assigned to a plurality of segments, in order to improve reproduction reliability, a device such as DC-free modulation that makes the number of segments annealed for each bit constant is also preferable.
[0048]
FIG. 5 shows an example of ID information recorded on the ID track 106a. If only the ID of the annealing device is sufficient, 16 bits are sufficient. However, since the recording of ID information here is carried out in a non-volatile manner for each of the optical discs 100, the media information that has been spreading rapidly in recent years. It is considered effective to expand and use as a media ID used for distribution. Another advantage is that no new process is required.
[0049]
(5a) is an example of simple ID information. 401 is a device ID, and 402 is the error detection code CRC. Here, double writing is performed in order to improve reading reliability.
[0050]
(5b) and (5c) are examples of ID information in which an ID is given to each optical disc 100 and the manufacturing history is also known. Reference numerals 403, 404, and 405 denote the manufacturer ID, date of manufacture, and serial number of the optical disc 100, respectively. As the serial number 405, a serial number initialized every manufacturing date is sufficient. The assignment ID 406 is a number given from a copyright management mechanism or the like. Reference numerals 407 and 408 respectively denote an error detection code CRC and an error correction code ECC for the above collection of information 413. In this example, it is assumed that the information set 413 is used as a media ID.
[0051]
(5c) is an example in which the information set 413 is divided into the information set 414 excluding the grant ID 406 and the grant ID 406. 409 and 410 are the former CRC and ECC, and 411 and 412 are the latter CRC and ECC. As a result, the information set 414 and the assigned ID can be used as different media IDs. In addition to the media ID, the ID information records the pit signal quality inspection result data of the optical disk that is considered to be suitable for the annealing apparatus at the same time, and the location where the error occurred during annealing. Is also possible.
[0052]
FIG. 6 is a block diagram of the main part of the annealing apparatus used in the annealing process of this embodiment. In FIG. 6, 501 is a half-wave laser of GaN of λ = 405 nm, 502 is an irradiation power detector that measures part of the emitted light of the semiconductor laser 501 as irradiation power, 503 is a beam splitter, 211 is NA0.75. It is an objective lens. Laser light emitted from the semiconductor laser 501 passes through the beam splitter 503 and the objective lens 211, and is condensed on the land 203 of the optical disc 100 to form an annealing light beam 212. The emission power of the semiconductor laser 501 is controlled by the annealing power control unit 506 by a normal power servo system based on the detection result of the irradiation power detector 502.
[0053]
The annealing light beam 212 is absorbed by the laminated thin film 200 of the optical disc 100 and changed into heat, and is reflected and returned to the annealing optical head 500 as reflected light. A λ / 4 plate (not shown) is disposed between the objective lens 211 and the beam splitter 503, and the reflected light is guided to the reflected power detector 505 by changing the optical path by the beam splitter 503. The output of the reflected power detector 505 is used for focus error signal detection, tracking error signal detection, track address reading, and the like. Reference numeral 507 denotes an optimum annealing power setting unit, in which a setting power value is set as a code in a DIP switch or an EEPROM, and a series of processing of the annealing apparatus is performed based on the value.
[0054]
Reference numeral 508 denotes an ID setting unit, which also stores device ID information in a DIP switch or EEPROM, and ID information is created based on this value and recorded in the ID track 106a. When expanding the ID information as shown in FIGS. 5 (5b) and (5c), it is preferable to send information from the host controller using the annealing apparatus as a slave. If the CRC and ECC are calculated in advance by a microcomputer for controlling the annealing apparatus (not shown), the increase in the amount of hardware can be reduced.
[0055]
FIG. 7 is a block diagram of the main part of the optical disk inspection apparatus used in the optical disk inspection process of this embodiment. In FIG. 7, 601 is a half-wave laser having a wavelength λ = 650, 602 is an emission (irradiation) power detector that measures a part of the emitted light of the semiconductor laser 601 as irradiation power, 603 is a beam splitter, 604 is NA0. 6 objective lens. Laser light emitted from the semiconductor laser 601 passes through the beam splitter 603 and the objective lens 604, and is condensed on the groove 202 of the optical disc 100 to form a recording / reproducing light beam 610. The output power of the semiconductor laser 601 is controlled by the recording / playback control unit 606 based on the detection result of the output power detector 602.
[0056]
The recording / reproducing light beam 610 is linearly polarized in order to detect the MO signal. The light beam 610 records information by magnetizing the laminated thin film 200 of the optical disc 100 with the magnetic head 609 while magnetically modulating the magnetic head 609 as recording power (frequency constant pulse modulation) during recording. The light beam 610 applies reproduction power to the laminated thin film 200 at the time of reproduction, and detects a domain wall motion and / or a normal magneto-optical state as a Kerr rotation angle change as an MO signal. The light beam 610 reflected as the MO detection signal returns to the objective lens 604 and is guided to the MO signal detector 605 by the beam splitter 603. The MO signal detector sends an MO differential signal and an addition signal for sample servo / address reading to the recording / playback control unit 606 in addition to the focus error signal and tracking error signal. Reference numeral 607 denotes an optimum annealing power storage unit that stores the optimum annealing power obtained in step S311 performed by the recording / playback control unit 606. Reference numeral 607 denotes a reproduction ID storage unit that stores the ID information read in the ID reproduction step S312 performed by the recording / playback control unit 606. If the CRC and ECC of the ID information are calculated later by a microcomputer for controlling the optical disc inspection apparatus (not shown), the addition of hardware can be reduced.
[0057]
In the above-described embodiments of the present invention, the sample servo optical disk has been described as a specific example in the DWDD reproduction method. However, the present invention is not limited to the recording material of the DWDD optical disc, but improves the characteristics of magneto-optical materials other than DWDD, and applies a predetermined power between the tracks of the phase change material to stabilize the reflectance and recording characteristics. It can also be applied to annealing between tracks in order to make it easier. Needless to say, the servo system can also be used for continuous servo. Furthermore, it is considered that the present invention can be effectively used for manufacturing other than the optical disk, such as forming a guide with a light beam on the magnetic disk.
[0058]
【The invention's effect】
As is clear from the above description, if the optical disk according to the present invention and the manufacturing method thereof are used, the annealing power of the annealing apparatus used in the annealing process can always be kept optimal, and the optical disk annealed with the optimal annealing power always. The manufacturing apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing the structure of an optical disc according to an embodiment of the present invention.
FIG. 2A is a cross-sectional perspective view of an optical disc according to an embodiment of the present invention.
(B) Enlarged view of the optical disc in the embodiment of the present invention
FIG. 3 is a diagram showing a manufacturing process and a manufacturing procedure in the embodiment of the present invention.
FIG. 4 is an explanatory diagram of an ID recording / reproducing method according to an embodiment of the present invention.
FIG. 5 is a diagram showing a data example of ID information in the embodiment of the present invention.
FIG. 6 is a block diagram of an annealing apparatus used in an optical disc manufacturing process according to an embodiment of the present invention.
FIG. 7 is a block diagram of an optical disc inspection apparatus used in an optical disc manufacturing process according to an embodiment of the present invention.
[Explanation of symbols]
100 optical disc
101 Data area (recording / playback track)
102 segments
103 Pit area
104 Groove area
105 Lead-in area
105a control track
105b Track for annealing power test
105c ID truck
106 Lead-out area
106a ID truck
106b Track for annealing power test
200 Multilayer thin film
201 substrate
202 Groove
203 rand
204 1st wobble pit
205 2nd wobble pit
206 Address pit
207 First dielectric layer
208 Magnetic layer
21 Domain wall moving layer
22 Barrier layer
23 Recording layer
209 Second dielectric layer
210 Magnetic coupling blocking region
211 Objective lens (for annealing)
212 Light beam for annealing
213 Mirror part
S301 Molding / Filming process
S302 Annealing process
S303 Protective coat and assembly process
S304 Disc inspection process
S305 Packing / shipping process
S306 Annealing power adjustment
401 Device ID
402,407,409,411 CRC
403 Manufacturer ID
404 Date of manufacture
405 serial number
406 Grant ID
408, 410, 412 ECC
500 Optical head for annealing
501 Semiconductor laser
502 Irradiation power detector
503 Beam splitter
505 Reflected power detector
506 Annealing power controller
507 Optimal annealing power setting part
508 ID information setting part
600 Optical head for recording and playback
601 Semiconductor laser
602 Output power detector
603 Beam splitter
604 Objective lens
605 MO signal detector
606 Annealing power controller
607 Optimal annealing power storage
608 Playback ID storage unit
609 Magnetic head
610 Light beam for recording and reproduction

Claims (7)

An optical disk that anneals both sides of a recording / playback track for recording / reproducing data with a light beam of a predetermined power, and a plurality of test tracks for finding the optimum power for the annealing, and annealing for performing the annealing An optical disc comprising an ID track for recording / reproducing an apparatus identification number (ID). Each bit recording of the ID of the ID track is a recording method in which recording is performed with or without annealing a plurality of sections having a predetermined length or longer with the predetermined annealing power or higher annealing power. Records data of a predetermined pattern in advance on the entire ID track, and after the recording, discriminates whether there is no annealing or not according to the presence / absence or large / small of the data for each section on the ID track. 2. The optical disk according to claim 1, wherein the reproduction method reproduces each bit of the ID. In addition to the ID, number information based on a predetermined rule is recorded on the ID track, and the ID and / or the number information is used as a media ID for data management for recording / reproducing the number information on a pre-recording / retrack. The optical disc according to claim 1 or 2, wherein An optical disc that anneals both sides of a recording / reproducing track for recording / reproducing data with a light beam of a predetermined power, a plurality of test tracks for finding the optimum power for the annealing, and an annealing apparatus for performing the annealing A method of manufacturing an optical disc having an ID track for recording / reproducing the identification number (ID) of
A first step of annealing both sides of the pre-recording re-track with a set power corresponding to the predetermined power, and creating an anneal inspection track in which the test track is annealed with a plurality of different powers centered on the set power An annealing step of annealing the optical disc using the annealing apparatus including a second step;
A third step of writing / verifying part or all of the annealed recording / reproducing track to determine the quality of the pre-recording / retracking, and writing / verifying the annealing inspection track to obtain the optimum annealing power of the annealing apparatus. An inspection step of determining pass / fail of the optical disc using an optical disc inspection apparatus including a fourth step of finding out;
An optical disk manufacturing method comprising an annealing power adjustment step of changing the set power to the optimum annealing power found in the inspection step. The annealing process includes a plurality of annealing apparatuses to which IDs are assigned, each annealing apparatus includes a fifth step of recording each ID on the ID track, and the optical disk inspection apparatus in the inspection process includes the ID A sixth step of reading an ID from a track, wherein the annealing power adjustment step changes the set power to an optimum annealing power for each of the annealing apparatuses specified by the ID from the plurality of annealing apparatuses. The method of manufacturing an optical disk according to claim 4. Each bit recording of the ID of the ID track in the fifth step is a recording method in which recording is performed with or without annealing a plurality of sections having a predetermined length or more with the predetermined annealing power or higher annealing power. Yes, the reproduction of the ID is performed by previously recording data of a predetermined pattern on the entire ID track, and after the recording, there is no annealing depending on presence / absence or large / small of the data for each section on the ID track 6. The method of manufacturing an optical disc according to claim 5, wherein the reproducing method is to discriminate the presence / absence portion and reproduce each bit of the ID. 7. The method of manufacturing an optical disc according to claim 5, wherein the fifth step records number information based on a predetermined rule in addition to the ID as the media ID on the ID track.

Images