JP2009170095A - Optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable excellent reading of an address signal at a low error rate in an optical disk having a first region composed of grooves having sinusoidal deflection and dispersed address pits and a second region composed of pit rows for preventing copying and dispersed address pits. <P>SOLUTION: The optical information recording medium has a supporting body and a recording layer including at least a rewritable phase change material and having at least 18 to 30% reflectance. An address output value to be an address pit signal component occupying in a playback signal in an unrecorded state lies in a range of 0.18 to 0.27 or the numerical aperture of an address pit signal occupying in the reproduction signal in the unrecorded state is 0.3 or more. The refractive index of the supporting body in a reproduction wavelength λ is 1.45 to 1.65. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical information recording medium used for a recording / reproducing apparatus (drive) for an optical information recording medium that writes and reads information by making a relative movement with respect to the optical information recording medium. The present invention relates to an optical information recording medium capable of recording and reproducing with a high density and a large capacity.

  2. Description of the Related Art Conventionally, there is a system capable of optically recording or reproducing using a disk-shaped medium as an information recording medium system that reads information by performing relative motion. The disc system is roughly classified into a read-only type (ROM type), a write-once type (write-once (R type)), and a recordable type (multiple-recording type (RW type)). In general, the recording density is high for reproduction only and is low for write-once type and recording type. For example, in a DVD system (laser wavelength 635 to 650 nm) that appeared in 1996, a read-only type (DVD-ROM, DVD video) precedes, and its recording capacity is 4.7 GB. On the other hand, the recordable DVD-RAM has a capacity of 2.6 GB, which is about 55% of the capacity of ROM. Although research and development for increasing the capacity of a recordable disc is in progress, a system having the same capacity as a DVD-ROM has not yet been completed.

  In the case of the recording type, the recording format on the disk, the material of the recording medium, etc. are important technologies. By the way, the DVD-RAM uses land / groove recording in which both the land and the groove of the optical information recording medium are used for recording. Here, addresses (addresses) necessary for recording and reproduction are recorded by cutting lands and grooves at specific intervals.

  FIG. 19 is a plan view showing the fine structure 20 (physical format structure) of the land / groove recording disk. FIG. 19 shows the appearance of the structure when not recorded, and the grooves 21 are formed in parallel. Between the grooves 21, there are lands 22, and information is recorded on both of them when recording. The address pits 23 necessary for recording / reproduction are formed by cutting the lands 22 and the grooves 21. Since this address occupies a certain area 24 together with an accompanying signal, this hinders an increase in capacity. In other words, the limited area could not be used effectively.

  For recording materials, in view of compatibility with a read-only DVD drive, a phase change recording method that does not use a magnetic head is suitable. However, this method has a drawback that the reflectance is significantly lower than that of the read-only type or the write-once type using a dye, and this also causes the recording capacity not to be improved.

  By combining and optimizing a fine structure (physical format structure) with high surface area utilization efficiency and a phase change material for high-density recording, there is a possibility that a recording capacity comparable to a read-only DVD may be achieved.

JP 11-86345 A Japanese Patent Laid-Open No. 7-44873

As a format suitable for a large-capacity optical disk, for example, an optical disk that does not have a specific address area such as the area 24 shown in FIG. That is, since there is no address area (area 24), there is a possibility that the recording density can be improved to the same level as a DVD-ROM. However, in this method, when the main recording signal is recorded in the vicinity of the address signal, an error may occur due to interference with the address signal, and subsequent rewriting may not be possible, and conversely, the address signal becomes the main recording signal. Leakage interference could cause read errors.
An object of the present invention is to propose a high-density phase-change optical information recording medium (recording disk) in which main recording signals and address signals can be recorded and reproduced without interfering with each other, and in particular, this object is realized. An address signal output range and a specific fine structure such as an address signal are shown by dimensions.
Further, the present invention is not limited to the DVD, and is to represent the fine structure dimensions by a general formula corresponding to a recording / reproducing apparatus using a short wavelength laser under development.
Another object of the present invention is to provide a high-density phase-change optical information recording medium (recording disk) having both the above-described recording / reproducing area and an area having a pit row and an address signal for preventing illegal copying. The size of the address signal performance range that allows recording and playback with minimum mutual interference between the main recording signal and the address signal and good readout of the address signal when not recorded, and the specific fine structure of the address signal, etc. There is to show.

In order to solve the above-mentioned problems, the present invention comprises a sine wave deflection groove, a first land, and first address pits having a predetermined length arranged in a distributed manner on the first land. A fine structure comprising a first region having a fine structure, a sinusoidal deflection pit row, a second land, and second address pits having a predetermined length arranged dispersed in the second land. A support having a second region, a recording layer having a reflectivity of 15% or more including at least a rewritable phase change material formed on the microstructure, and a resin layer formed on the recording layer; Information is modulated and recorded by varying the length of the recording mark on the sine wave deflection groove of the recording layer, while optical information reproduced by a quadrant detector using a reproduction wavelength λ On recording media I,
The phase change material is a phase change material having a high reflectance when not recorded and a low reflectance after recording,
The quadrant detector has four regions divided by a straight line in the radial direction of the optical disc and a straight line in the tangential direction orthogonal to the radial direction, and the inner circumference of the optical disc divided by the straight line in the tangential direction. The first address pits observed as differential output values between the first composite output value output from the two areas on the side and the second composite output value output from the two areas on the outer periphery side of the optical disc When the peak signal output value is divided by the total combined output value output from the four regions of the four-divided detector, the refractive index of the support is set to be in the range of 0.18 to 0.27, The track pitch of the sine wave deflection groove, the depth of the sine wave deflection groove and the first address pit, the width of the sine wave deflection groove, the length of the first address pit, and the recording mark Chino together with defining the shortest mark length,
The track pitch of the sine wave deflection pit row is the same as the track pitch of the sine wave deflection groove,
The depth of the sine wave deflection pit row, the depth of the second address pit, the depth of the sine wave deflection groove, and the depth of the first address pit are all the same,
The width of the sine wave deflection pit row and the width of the sine wave deflection groove are the same,
The length of the second address pit is the same as the length of the first address pit;
An optical information recording medium is provided wherein the shortest pit length of the sine wave deflection pit row and the shortest mark length are the same.

In the optical disc of the present invention, address pits are dispersedly recorded on the land, and a high-density recording type optical disc can be realized by using a phase change recording layer having a reflectance of 15% or more. The disc possessed can minimize the mutual interference between the recording mark in the groove and the address pit signal, and can perform good recording and reproduction. In addition, since the dimensions of the disk support microstructure are specified, stable disk manufacture and supply are possible.
In another optical disk according to the present invention, a high-density phase change type optical disc having both a recording / reproducing area in which address pits are dispersedly recorded on a land, and a pit row for preventing illegal copying and an area having dispersed address signals. An information recording medium (recording disk) is provided. Further, by setting the aperture ratio of the address signal within a specific range, reading at a low error rate is possible. Further, since the disk support fine structure for realizing this is specified by dimensions, stable disk production and supply are also possible.

It is a bird's-eye view which shows the Example of this invention. 1 is an enlarged plan view showing fine structures (physical formats) 10 and 101 according to an embodiment of the present invention. It is another enlarged plan view which shows the physical format of the Example of this invention. It is a figure which shows each relationship between the groove depth d and the output (PPb) of a push pull signal. It is a figure which shows the result of having measured the value of the jitter with respect to groove depth d and groove width. It is a schematic diagram of a quadrant detector. It is a figure which shows the reproduction | regeneration waveform of an unrecorded state. It is a reproduction waveform in a recording state. It is a figure which shows the measured value of the error rate of an address pit. It is the figure which measured the error rate of the recording mark. It is a figure which shows the relationship between (k) which is (address pit length (AL) / recording information mark length (ML)), and address pit output value APb. It is a figure which shows the relationship between an address pit length (AL) and an address pit output value (APb). It is a figure which shows the relationship between (k) which is (address pit length (AL) / recording information mark length (ML)), and an address pit output value (APb). 1 is a cross-sectional view of an optical disc 1. FIG. 1 is a diagram showing a cross-sectional structure of an optical disc 1 in Examples 1 and 3. FIG. It is a figure which shows the cross-section of the optical disk 1 of Example 2 of this invention. It is a physical configuration format showing an example of address information. It is a figure explaining an example of the manufacturing method of this invention. It is a top view which shows the fine structure 20 (physical format structure) of a land groove recording type disk. It is a top view which shows the Example of this invention. It is an enlarged plan view which shows the microstructure 102 of the Example of this invention. It is a figure which shows the reproduction | regeneration waveform of the unrecorded state in the fine structure. It is a figure which shows the measured value of the error rate of the address pit in the fine structure. 6 is a diagram showing a cross-sectional structure of an optical disc 100 of Example 4. FIG. It is a top view which shows Example 3, 4 of this invention. FIG. 10 is a diagram illustrating signal characteristics of a second area in the optical disc 100 according to the third embodiment. It is a figure explaining the manufacturing method of Example 2, 3. FIG. 6 is a diagram for explaining a production method of Example 4. FIG.

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The inventor of the present invention has arrived at the present invention as a result of diligent development while keeping in mind that semiconductor lasers of various wavelengths will appear in the future. In other words, many prototypes and evaluations were repeated, and the same recording capacity (4.7 GB) as that of a read-only DVD was realized at a recording / reproducing wavelength of 635 to 650 nm, and the system was established even with a laser with a shorter wavelength of 600 nm or less. It came to establish the method.

  Next, the present invention will be described with reference to the drawings. FIG. 1 is a bird's-eye view showing an embodiment of the present invention. The optical disk 1 shown in FIG. 1 is a system for recording information only in the groove 11, and the groove 11 as an information track and an address pit 13 (not shown) described later are concentric or spiral with respect to the disk. Embedded to form the microstructure 10. The cross-sectional view is as shown in FIG.

  FIG. 14 is a cross-sectional view of an embodiment of the present invention, illustrating the most basic configuration of the embodiment of the present invention. That is, the optical disk 1 is laminated in the order of the support 2, the recording layer 3, and the resin layer 4. Recording / reproduction by light is performed on the recording layer 3, from which the laser beam (wavelength λ nm) narrowed down by the objective lens (numerical aperture NA) is irradiated, that is, incident from the support 2 side, resin layer Whether the light enters from the 4th side is arbitrary. The light incident path, that is, the optical path has a predetermined refractive index n with respect to the wavelength λ, and the effective optical length is determined by the refractive index n. In FIG. 14, the support 2 is illustrated as an optical path as an example. The fine structure 10 including the groove 11 is embedded in the optical disc 1, specifically, formed on the surface of the support 2. The support 2 and the recording layer 3 are formed in parallel to each other.

  FIG. 2 is an enlarged plan view showing a fine structure (physical format) 10 according to the embodiment of the present invention, and schematically shows a state when recording is not performed. Here, the fine structure 10 indicates a physical format of the optical disc 1. Grooves 11 are formed on the support 2 of the optical disc 1 substantially in parallel. In order to extract the clock, each groove 11 is deflected at an integral multiple frequency with respect to the sync frame frequency of the entire system, and has a sine wave shape. This waveform may or may not be synchronized with the adjacent groove.

Address pits 13 are formed in a distributed manner on the lands 12 between the grooves 11 and carry address information. That is, the address pits 13 are embedded in the support 2 in advance so as to bridge the adjacent tracks (in an I shape). Specifically, the sine wave deflection groove 11 and the address pits 13 distributed between the grooves 11 are formed on the support 2 with the same depth. Since the address pits 13 bridge between the grooves 11 in this way, the address pits 13 can be read when either of the grooves 11 is used. In other words, it is arbitrary whether the inner circumference side is the address or the outer circumference side is the address with respect to the groove. The address pit 13 is arranged at a position where the sine wave groove 11 is deflected to the maximum (within the sine wave apex ± 10 degrees).
Address information is recorded based on the distance between the address pits 13. Therefore, the length (AL) of the address pit 13 itself is constant. FIG. 17 is an information format showing an example of address information. There is a sync bit (synchronization signal) at the beginning, followed by relative address data, and consists of ECC block address data (ECC: error correction code). For example, the sync has a configuration of 1 bit, relative address data of 4 bits, and ECC block address data of 8 bits.

  FIG. 3 is another enlarged plan view showing the physical format of the embodiment of the present invention, and schematically shows a state during recording on the optical disc 1. The configuration is basically the same as that in FIG. 2, but the information mark 14 is deflected and recorded in the groove 11. The information mark is recorded by phase change recording, i.e., recording layer material change.For example, the unrecorded state is crystalline and the recorded state is amorphous. It can be reproduced by utilizing the low reflectivity of the crystalline. However, depending on the selection of the material, it is possible to have a low reflectance when not recorded and a high reflectance when recording.

  The information mark 14 is a signal modulated by a known digital code, and is a signal that is an integral multiple of the channel bit (T). Therefore, all signals having the shortest mark length of 2T, 3T, 4T, 5T, etc. can be handled as in the known optical disc. For example, in a signal system in which the shortest mark length is 3T, a signal system composed of signals from 3T to 11T such as 8/14 modulation, 8/15 modulation, and 8/17 modulation, or 3T to 11T such as 8/16 modulation. A signal system composed of signals and 14T signals can be handled.

  As described above, in the optical disc 1 according to the embodiment of the present invention, the address pits 13 are distributed and recorded on the lands 12, and the specific area 24 is not provided unlike the land groove system, so that the area utilization efficiency is good. In addition, since the information mark 14 is recorded in the groove 11, it has a structure with little interference with the address pit 13 on the land 12. However, as shown in FIG. 3, the address pit 13 and the information mark 14 may be adjacent to each other, and sufficient attention must be paid to the readability of the address pit 13 and the readability of the information mark 14 after adjacent recording.

  By the way, for the material of the recording layer 2 used in the optical disc 1 which is an embodiment of the present invention, a phase change material in which the reflectance of the recording layer 2 is 15% or more is suitable, and preferably a high reflectance of 18% or more. The phase change material is suitable. Particularly suitable is a phase change material which is an alloy containing antimony, tellurium and a metal having a melting point of 1100 ° C. or less and which can provide a large reflectance contrast before and after recording. For example, as a material having practical recording sensitivity and practical signal characteristics (modulation degree, reflectance, jitter, rewritable number), antimony and tellurium are essential components, and gold, silver, copper, indium and aluminum are included in these. A material containing at least one of germanium is desirable. Particularly desirable are silver / indium / antimony / tellurium alloy (AgInSbTe), copper / aluminum / tellurium / antimony alloy (CuAlTeSb), germanium / antimony / tellurium alloy (GeSbTe), silver / germanium / antimony / tellurium alloy (AgGeSbTe), Gold, germanium, antimony, tellurium alloy (AuGeSbTe) and the like.

  Here, various dimensions are defined in order to explain the recording / reproducing performance described later. In FIG. 2 (unrecorded state), the distance between the center lines of the sine wave deflected groove 11 is defined as the track pitch TP, the width of the groove 11 itself is defined as w, and the address pit 13 Define the length as AL. Since the address pits 13 are driven almost in the center of the land 12, the distance between the center line of the address pits 13 and the center line of the groove 11 is approximately TP / 2 (not shown). Further, the groove 11 and the address pit 13 are both engraved at the same depth with respect to the support 2, and although not shown in the drawing, the depth is both d. In FIG. 3 (recording state), the length of the information mark 14 after recording has various lengths due to modulation, and the length of the shortest mark is ML.

  Using these phase change materials for high-density recording, optical disks with various fine structure dimensions (TP, d, w, ML, AL) were actually made and evaluated for recording / reproducing characteristics. The numerical value range of the address output of the optical disc 1 and the range value of the fine structure dimension could be obtained. The optical disk and the optical disk drive described as an embodiment of the present invention are assumed to have a length of about 60 to 70% TP and about 35 to 45% ML with respect to the reproduction spot diameter (λ / NA). .

(1) Tracking performance of unrecorded disc Since the recording disc 14 having a difference in reflectance is formed in the groove on the recorded disc as shown in FIG. 3, various methods can be used for tracking. For example, DPD tracking or DPP tracking. However, when recording is not performed, only the groove 11 is used as shown in FIG. 2, and the tracking method can be practically only the push-pull method.

  The relationship between the groove 11 depth d and the push-pull signal output (PPb) was examined and shown in FIG. In addition, it measured about the range of W / TP = 0.35-0.55 here. As shown in FIG. 4, the smaller d is, the smaller PPb is. Although it becomes maximum at so-called d = 0.125λ / n (n is the refractive index of the optical path), the tracking itself is stable even with a relatively small PPb. When the limit of tracking of the phase change disk 1 with distributed address pits according to the present invention was actually investigated, Pb = 0.22. In other words, it is necessary that d ≧ 0.05λ / n.

(2) Recording mark reproduction performance Jitter is one of the indicators of the recording mark 14 reading performance. This is obtained by performing reproduction after recording and dividing the fluctuation (standard deviation) in the time axis direction by the clock. The smaller the numerical value, the more stable reproduction is obtained. For example, in the DVD standard, after passing through the equalizer, it is determined to be 8.0% or less.

  FIG. 5 shows the measurement of the jitter value (5 tracks, 10 times overwriting) with respect to the groove depth d and the groove width. The groove width is expressed by w / TP, a value obtained by standardizing the width w with respect to the track pitch TP. As shown in FIG. 5, the smaller the groove depth d, the better the jitter. The reason is that the shallower the groove, the higher the reflectivity and the degree of signal modulation, and the relatively lower base noise. The influence of the groove width w / TP on the jitter is relatively small.

  In order to obtain a jitter of 8.0% or less, although it depends on the groove width, it is necessary that d ≦ 0.1λ / n. Further, it is necessary that 0.35 ≦ (w / TP) ≦ 0.55. Since the address pit 13 is formed in an I shape with respect to each groove, the width of the address pit 13 itself takes a value of 0.65 to 0.45 in TP ratio.

(3) Address Pit Reproduction Performance and Interference from Record Marks A four-divided photodetector is used for a pickup of a reproduction apparatus represented by a DVD player. An address pit signal can be generated efficiently by adding / subtracting / dividing the respective outputs. FIG. 6 is a schematic diagram of the quadrant detector 9 as described above. Corresponding to FIGS. 2 and 3, the vertical axis is the radial direction, and the horizontal axis is the tangential direction (track direction). The reproduction outputs of the quadrant detector are Ia, Ib, Ic, and Id, respectively. Here, Ia and Ib are detectors arranged on the inner peripheral side and Ic and Id are arranged on the outer peripheral side corresponding to FIGS. . In reproduction, the address pits 13 can be reproduced with high contrast by synthesizing the outputs so that (Ia + Ib)-(Ic + Id).

7 and 8 show waveforms reproduced in this way. FIG. 7 shows a reproduction waveform in an unrecorded state, in which address pits 13 are synthesized with the waveform of the groove 11 deflected by a sine wave and reproduced. Thus, only the address pit 13 can be projected and detected, so that the address can be read. Therefore, a normalized value corresponding to this protrusion can be defined as an unrecorded address pit output. Specifically, a value obtained by dividing the absolute value of (Ia + Ib) − (Ic + Id) by the sum of all detectors, that is, the absolute value of (Ia + Ib + Ic + Id) is defined as an unrecorded address pit output (APb). The address pit output value (APb) means the value of the address pit signal component occupied in the unrecorded reproduction signal.
APb = | (Ia + Ib) − (Ic + Id) | / | (Ia + Ib + Ic + Id) |

  For accurate measurement, it is desirable to insert a filter to remove various noise components. For example, when measuring the absolute value of (Ia + Ib + Ic + Id), a low-pass filter having a cutoff of 30 kHz is inserted. Conversely, when measuring the absolute value of (Ia + Ib)-(Ic + Id), it is desirable to use an amplifier with a bandwidth of 20 MHz or more.

Since the address pit output value is obtained by the diffraction of the address pit 13, it strongly depends on the depth d and the length AL. If the address pit output value APb is small, it is difficult to read and the error rate tends to increase.
FIG. 8 shows a reproduction waveform in the recording state. The signal of the information mark 14 recorded in the groove 11 is overwritten on the waveform of FIG. Since this signal is superimposed on the groove 11 like noise, it greatly affects the reading of the address pit 13. In other words, even if the address pits can be correctly decoded when unrecorded, there may be cases where the address pits cannot be decoded after recording.

The error rate of the address pit before recording was measured for an optical disk manufactured by varying d and AL. Thereafter, random recording was performed on the groove 11, and then the error rate of the address pit was measured again. Note that the reliability condition is that the error rate after recording is less than 5%. FIG. 9 shows the measured values. Here, the horizontal axis is the address pit output value APb, and the vertical axis is the block error rate measured for 1000 ECC blocks or more. The error rate before recording (BER-b) and the error rate after recording (BER-a) are plotted together.
Thus, the larger the address pit output value APb, the easier it is to read the address pit and the lower the error rate. Comparing before and after recording, it is easy to read before recording, but after recording, it is easy to cause errors in reading. This is because the recording signal is likely to interfere, and a sufficient APb value is required. From the above, it can be said that the address pit output value APb needs to be 0.18 or more to ensure an error rate after recording of less than 5%. When a signal analysis is performed in detail when the error rate after recording is 5%, RF signal superposition is considerably observed, and the aperture ratio of the address pits in FIG. 8, that is, Δ / APs in FIG. 8 is only 10%. In other words, it can be said that Δ / APs is required to be 10% or more.

(4) Interference from address pit to recording mark Since address pit 13 and groove 11 are in partial contact, address pit 13 may interfere with reproduction of recording mark 14 after recording. Therefore, for the optical disc having various address pit output values (APb), the recording mark 14 was read and the number of errors was measured. FIG. 10 shows the measured values. Here, the horizontal axis is the address pit output value APb, and the vertical axis is the number of PI errors (the number of erroneous block sequences of 1 byte or more for consecutive 8 ECC blocks). It can be seen that errors increase sharply at a certain value of APb. It is understood that the diffracted light of the address pit 13 interferes with the recording mark 14 and causes a reading error. For example, since the DVD standard requires that the PI error is 280 or less, the address pit output value APb is suitably 0.27 or less.

(5) Size of fine structure for obtaining desired address pit output value APb As described above, the optical disk and drive according to the present invention assume a small TP and a small shortest mark length with respect to the reproduction spot diameter (λ / NA). Yes. Further, as discussed in (1) and (2), a depth sufficiently shallower than the reproduction wavelength is assumed. The conditions of AL and d for obtaining a desired address pit output value APb under such conditions were examined.

Since AL and ML are considered to be relatively the same order in view of mutual interference, it is assumed that k = AL / ML, the value of k and the address pit output value APb, and the value of d and the address pit output. The value APb was examined. As a result, it was found that APb increases as d increases and k increases. Specifically, APb can be expressed by the following function.
APb = 0.14k + 4.11n (d−26) / λ

As described above, the address pit output (APb) that does not hinder the actual operation of the recording / reproducing drive has been obtained, and the dimensions (TP, d, w, k) of various microstructures have been studied. The above studies (1) to (5) can be summarized as follows.
That is, the range of the address pit output value (APb) which is the address pit signal component occupied in the unrecorded reproduction signal:
0.18 <APb <0.27
Various fine dimensions satisfying the above address pit output:
0.05λ / n ≦ d ≦ 0.1λ / n and 0.35 ≦ (w / TP) ≦ 0.55 and 0.18 <0.14k + 4.11n (d−26) / λ <0.27
Dimensions d, w, and k satisfying the following relationship simultaneously.

  As described above, the optical disc 1 having the address pit output according to the present invention can minimize the mutual interference between the recording mark 14 in the groove and the address pit 13 and perform good recording and reproduction. Further, the support 2 having the fine structure dimensions according to the present invention and the optical disc 1 containing the same can minimize the reproduction interference between the recording mark 14 and the address pit 13.

Further, the present invention specifies the fine structure dimensions of the support 2 when manufacturing such a disk 1, and thus enables stable manufacture and supply. Next, a specific manufacturing method according to the present invention will be described with reference to FIG. A known blank master (resist board) is mastered by a laser beam recorder (LBR) to form the microstructure 10 according to the present invention (FIG. 18a). For this, for example, a recorder with a built-in laser whose light source is a wavelength of 458 nm, 442 nm, 413 nm, 407 nm, 364 nm, 351 nm, 325 nm, 275 nm, 266 nm, 257 nm, 244 nm, etc. is desirable. is there. Specifically, the master beam is used for forming the groove 11 and the sub beam is used for forming the address pit 13. The master beam is deflected by a sine wave by passing a deflector (for example, EOD or AOD). Further, the sub beam is intermittently modulated by passing a modulator (for example, EOM or AOM).
The mastering by the two beams is preferably performed at the same time because the positional accuracy is insufficient when each is performed independently. In that case, it is necessary to set the interval between the master beam and the sub beam to TP / 2. At this stage, an image is recorded on the blank master, but the shape is not changed.

  Subsequently, a known alkali development is performed on the recorded blank master to convert the mastering image into irregularities (FIG. 18b). This shape has a microstructure 10 that is substantially the same as the support 2 described later. The glass master is subjected to a known stampering process, that is, a conductive process and an electroforming process to form a stamper (FIG. 18c). This shape has a fine structure in which the unevenness is substantially reversed from that of the support 2 described later.

  Then, using the obtained stamper, known forming is performed to constitute the support 2 (FIG. 18d). The material of the support 2 is polycarbonate resin, polysulfone resin, polyphenylene oxide resin, polystyrene resin, polynorbornene resin, polymethacrylic resin, polymethylpentene resin, various copolymers having these resin skeletons, block polymers, etc. These synthetic resins can be used. However, when the support 2 is used as an optical path, attention must be paid to its optical characteristics such as refractive index (n) and birefringence, as is well known. For example, when the refractive index is n = 1.45 to 1.65 and the birefringence is 100 nm or less in a double pass, compatibility with the DVD can be kept good.

Then, the recording layer 3 is formed on the support 1. Specifically, the recording layer 3 is formed on the microstructure 10 (FIG. 18e). The phase change material which is the main component of the recording layer 3 is as described above, but may be sandwiched between various optical interference films for the purpose of adjusting the optical characteristics, adjusting the heat propagation characteristics, and the like as necessary. For example, dielectric materials such as SiN, SiC, SiO, ZnS, ZnSSiO, GeN, AlO, MgF, InO, and ZrO are useful. Among them, ZnSSiO (mixture of ZnS and SiO ₂ ) is a phase change recording material. Especially good heat balance.
Alternatively, the recording layer 3 may be configured by laminating a known light reflecting film (aluminum, gold, silver, or an alloy containing these) together for the purpose of adjusting the reflectance, adjusting the heat propagation characteristics, and the like. In order to perform high-density recording / reproduction, a known super-resolution mask film or contrast enhancement film may be used in combination. As a method for forming such a film, a known vacuum film forming method such as a sputtering method, an ion plating method, a vacuum vapor deposition method, or a CVD method can be used. In particular, the phase change material and the sputtering method are compatible with each other and have high mass productivity.

  Subsequently, the resin layer 4 is formed on the recording layer 3. This resin layer guards the recording layer 2 chemically or mechanically, and depending on the structure of the optical disc 1, it may be provided with adhesiveness. The material of the resin layer 4 can be selected from an ultraviolet curable resin, various radiation curable resins, an electron beam curable resin, a thermosetting resin, a moisture curable resin, a multiple liquid mixed curable resin, and the like. As a film forming method, a known spin coating method, screen printing, offset printing, or the like can be used.

  The method for manufacturing the optical disc 1 according to the present invention has been described above. The configuration diagram of the optical disc 1 shown in FIG. 14 is only basic, and various modifications are possible. For example, it may be bonded to another support to increase the strength, or two optical disks 1 shown in FIG. 14 may be prepared and bonded together to form a disk (double-sided disk or double-layer disk).

Example 1
An example in which the optical disk 1 according to one embodiment of the present invention is applied to a disk system using a red semiconductor laser will be described. Note that λ used is 650 nm, and the numerical aperture NA of the objective lens is 0.6. Therefore, the reproduction spot diameter (λ / NA) is 1083 nm (1.083 μm).

FIG. 15 shows a cross-sectional structure of an optical disc 1 that is one embodiment of the present invention. The support 2, the recording layer 3, the resin layer 4, and the dummy support 5 are laminated in this order. Here, the microstructure 10 described later is embossed on the surface of the support 2. Here, the support 2 is an optical path from the laser to the recording layer 3, and its thickness is 0.6 mm. Both the support 2 and the dummy support 5 are made of polycarbonate resin, and the refractive index n at 650 nm is 1.58. The recording layer 3 has a laminated structure mainly composed of a phase change material having a high reflectance when not recorded and a low reflectance when recording.
Specifically, the recording layer 3 is laminated by sputtering from the support 2 side in the order of ZnSSiO / AgInSbTe / ZnSSiO / AlTi. The reflectance is 18-30%. With this structure, the recording sensitivity at 650 nm is 7.5 to 14.0 mW. Recording can also be performed with 635 nm light, and the recording sensitivity can be maintained in the range of 7.0 to 13.0 mW, which is almost the same as 650 nm.

  The microstructure 10 when not recorded is as shown in FIG. The groove 11 has a spiral shape, and its track pitch TP is 0.74 μm, which is the same as DVD-ROM, and is sinusoidally deflected. The groove period is recorded at a frequency eight times that of the sync frame. The wave amplitude is arbitrarily set within the range of 9 to 17 nm. Further, the phase between adjacent tracks is random because of CLV (constant linear velocity) recording. An address pit 13 having a predetermined length AL is carved in accordance with the address value on the land outside the groove 11.

  The fine structure 10 at the time of recording is as shown in FIG. The signal to be recorded is an 8/16 modulation signal, and the shortest mark length ML is 0.40 μm. This value is the same as that of the DVD-ROM, and this makes it possible to realize a recording capacity of 4.7 GB on a 120 mm diameter disc (recording range is a radius of 24 to 58 mm). At this time, TP corresponds to 68% of the reproduction spot diameter, and the length (ML) of the shortest mark corresponds to 37%.

The recording mark 14 in the groove and the address pit 13 do not interfere with each other, and the range of address pit output in which satisfactory recording and reproduction can be performed, that is, the dimensions of various microstructures satisfying 0.18 <APb <0.27. The conditions are as follows.
0.05 · 650 / 1.58 ≦ d ≦ 0.1 · 650 / 1.58,
That is, 20 nm ≦ d ≦ 41 nm and 0.35 ≦ (w / 0.74) ≦ 0.55,
That is,
0.26 μm ≦ w ≦ 0.41 μm and 0.18 <0.14k + 4.11 · 1.58 (d−26) / 650 <0.27,
That is, 0.18 <0.14k + 0.01 (d−26) <0.27.
Here, since ML = 0.4 μm,
It can also be expressed as 0.18 <0.35AL + 0.01 (d−26) <0.27, that is, 44 <35AL + d <53.

  In particular, in order to clarify the range between d and k, the relationship between k and APb is displayed in a graph as shown in FIG. From the limitation of APb at d = 20 nm which is the limit of tracking performance and the limitation of APb at d = 41 nm which is the limit of jitter, d and k can take a range within the parallelogram shown in the figure. That is, it is a range surrounded by (d, k) = (41, 0.22), (41, 0.85), (20, 2.34), (20, 1.70). Considering manufacturing variations (manufacturing variation of groove depth d and address pit length AL), (d, k) = (39.5, 0.34), (39.5, 0.95), ( The range surrounded by 21.5, 2.23) and (21.5, 1.60) is desirable.

  Since ML = 0.4 μm, FIG. 11 can be rewritten by replacing k with AL. In FIG. 12, the horizontal axis is AL. The range of the present invention is a range surrounded by (d, AL) = (41, 0.08), (41, 0.34), (20, 0.94), (20, 0.68). In consideration of manufacturing variations, (d, AL) = (39.5, 0.136), (39.5, 0.380), (21.5, 0.892), (21. 5, 0.640) is preferable.

(Example 2)
An example in which the optical disk 1 according to the embodiment of the present invention is applied to a disk system using a green semiconductor laser will be described. Λ used is 532 nm, and the numerical aperture NA of the objective lens is 0.75. Therefore, the reproduction spot diameter (λ / NA) is 709 nm (0.709 μm).

  FIG. 16 shows a cross-sectional structure of an optical disc 1 that is an embodiment of the present invention. The support 2, the recording layer 3, the resin layer 4, and the transmission layer 7 are laminated in this order. Here, the microstructure 10 described later is embossed on the surface of the support 2. Here, the transmission layer 7 is an optical path from the laser to the recording layer 3, and the thickness thereof is 0.1 to 0.12 mm. The transmission layer 7 is an acetate resin, and the refractive index n at 532 nm is 1.6. The recording layer 3 is a phase change material having a high reflectance when not recorded and a low reflectance when recording, and mainly uses CuAlTeSb having a reflectance of 15 to 32%. Specifically, the recording layer 3 has a laminated structure, and is laminated in the order of AgPdCu / ZnSSiO / CuAlTeSb / ZnSSiO from the support 2 side. With this structure, the recording sensitivity at 532 nm is 4.5 to 7 mW.

  The microstructure 10 when not recorded is as shown in FIG. The track pitch TP of the groove 11 is 0.468 μm and is sinusoidally deflected. The period of the groove 11 is recorded at a frequency six times that of the sync frame. The wave amplitude is arbitrarily set within the range of 5 to 9 nm. Further, because of CAV (constant rotation speed) recording, the phases of adjacent tracks are accurately synchronized and are always completely parallel to each other. An address pit 13 having a certain length AL is carved in accordance with the address value on the land 12 inside the groove 11.

  The fine structure 10 at the time of recording is as shown in FIG. The signal to be recorded is an 8-15 modulation signal, and the shortest mark length ML is 0.269 μm. As a result, a recording capacity of 11.8 GB on a 120 mm diameter disk can be realized (the recording range is a radius of 24 to 58 mm). At this time, TP corresponds to 66% of the reproduction spot diameter, and the length (ML) of the shortest mark corresponds to 38%.

The recording mark 14 in the groove and the address pit 13 do not interfere with each other, and the range of address pit output in which satisfactory recording and reproduction can be performed, that is, the dimensions of various microstructures satisfying 0.18 <APb <0.27. The conditions are as follows.
0.05 · 532 / 1.60 ≦ d ≦ 0.1 · 532 / 1.60,
That is, 17 nm ≦ d ≦ 33 nm and 0.35 ≦ (w / 0.468) ≦ 0.55,
That is, 0.16 μm ≦ w ≦ 0.26 μm, and 0.18 <0.14k + 4.11 · 1.60 (d−26) / 532 <0.27,
That is, 0.18 <0.14k + 0.012 (d−26) <0.27.

  In particular, in order to clarify the range of 0.18 <APb <0.27, the relationship between k and APb is displayed in a graph as shown in FIG. From the limit of APb at d = 17 nm, which is the limit of tracking performance, and the limit of APb at d = 33 nm, which is the limit of jitter, the length of the address pit can take a range within the parallelogram shown in the figure. That is, it is a range surrounded by (d, k) = (33, 0.68), (33, 1.32), (17, 2.68), (17, 2.04).

  As described above, the embodiment of the present invention has been described with respect to the high-density optical disc 1 in which the address pits are arranged between the grooves. The above-described embodiment is merely an example of the present invention, and various modifications can be made in accordance with the spirit of the present invention. Various constituent elements can be interchanged with each other without departing from the spirit of the present invention. For example, the laser wavelengths used for reproduction or recording / reproduction are 650 nm and 532 nm, but are not limited thereto. For example, 830 nm, 635 nm, 515 nm, 460 nm, 430 nm, 405 nm, 370 nm, or the like can be used. The lens numerical aperture NA may be 0.4, 0.45, 0.55, 0.65, 0.7, 0.8, 0.85, 0.9, etc. in addition to 0.60 and 0.75. Is possible. Further, a numerical aperture of 1 or more typified by a solid immersion lens is also possible.

Further, the microstructure 10 shown in FIG. 2 is for explaining only the main part of the present invention in order to simplify the description. In addition to the groove, land, address pit, etc. shown in FIG. It may be chopped. For example, as the fine structure of the support 2, a pit row for carrying a lead-in signal and a pit row for preventing dump copy and counterfeiting are combined to an inner peripheral portion, for example, an arbitrary radial width within a range of 15 mm to 24 mm. It may be recorded. Further, a write-once information management area called BCA (described in US Pat. No. 5,617,408) may be similarly provided in the inner periphery.
Moreover, the thickness of various layers, its internal structure, external dimensions, and constituent materials can be changed as needed.

  As described above, the optical disc 1 according to the present invention (a support on which sinusoidal deflection grooves and address pits dispersed between the grooves are formed, a recording layer having a reflectivity of 15% or more including at least a rewritable phase change material, and Two examples have been described for an optical disc comprising at least a resin layer formed on a recording layer, and means for extending the present invention to other than these examples have been described. Next, as an application example, an optical disc 100 in which a special pit row for preventing dump copy (a whole copy of software) is provided in another area and address pits are embedded in the pit row will be described.

  FIG. 20 is a plan view of an optical disc 100 according to the present invention, which is composed of a fine structure 101 in a first region and a fine structure 102 in a second region. The fine structure 101 in the first region is a region where sinusoidal deflection grooves and address pits distributed between the grooves are formed, and has the same fine structure as the fine structure 10 in the optical disc 1 of the present invention described above. ing. That is, the fine structure in an unrecorded state is the same as in FIG. Further, recording can be performed on the groove 11, and the fine structure of the recording state is the same as that shown in FIG.

The fine structure 102 in the second region is composed of at least address pits arranged in a pit row and land portions. An example of the microstructure 102 is shown in an enlarged plan view in FIG. FIG. 21 schematically shows an unrecorded state, in which pit rows 15 (shortest pit length PL, pit width is W2) composed of copy-preventing modulation signals are substantially parallel to the support 2. In rare cases, a track is formed (track pitch is TP2). In order to extract the clock, each pit row 15 is deflected at an integral multiple frequency with respect to the sync frame frequency of the entire system, and has a sine wave shape. This waveform may or may not be synchronized with the adjacent pit row. Address pits 13 are distributed and engraved between the tracks, that is, in the land portion 12, and carry address information. That is, since the address pit 13 is formed in the land portion 12, it can be read out by a reproducing / recording / reproducing apparatus having the four-divided detector 9, like the optical disc 1 described above.
Address information is recorded based on the distance between the address pits 13. Therefore, the length (AL2) of the address pit 13 itself is constant. FIG. 17 is an information format showing an example of address information. There is a sync bit (synchronization signal) at the beginning, followed by relative address data, and consists of ECC block address data (ECC: error correction code). For example, the sync has a configuration of 1 bit, relative address data of 4 bits, and ECC block address data of 8 bits. Here, it is arbitrary whether the inner peripheral side is the address or the outer peripheral side is the address with respect to the pit row 15. The address pit 13 is arranged at a position where the sine wave groove 11 is deflected to the maximum (within the sine wave apex ± 10 degrees). The pit row 15 and the address pit 13 have the same depth d2 (not shown).

The optical disc 100 according to the present invention has two different fine structures, that is, fine structures 101 and 102, and the arrangement thereof is arbitrary. That is, it may be arranged on either the inner peripheral side or the outer peripheral side. Furthermore, a structure in which the fine structure 102 is housed in the fine structure 101 may be used. The vertical cross-sectional structure of the optical disc 100 according to the present invention includes at least the support 2, the recording layer 3, and the resin layer 4 like the optical disc 1. For example, any of FIGS. The recording layer 3 includes at least a phase change recording material and has a reflectance of 15% or more.
The microstructures 101 and 102 may have different physical parameters such as different track pitches (TP, TP2), different depths (d, d2), and different widths (w, w2). However, in order to simplify the system and facilitate disk manufacture, it is desirable that some of the parameters are the same, and it is more desirable that all are the same. In addition, the recording layer 3 and the resin layer 4 also preferably have the same composition and the same film thickness on the fine structure 101 and the fine structure 102. As for the address information to be engraved, it is desirable to share a consistent table between the fine structures 101 and 102 and use them so as not to overlap each other.

  Since the first area (fine structure 101) of the optical disk 100 according to the present invention is an area for recording / reproducing, as with the optical disk 1 described above, it is necessary to read the address information both when unrecorded and during recording. It is necessary to consider the coherence with respect to. For this purpose, a signal output and a fine structure dimension that satisfy the conditions (1) to (4) described above are required.

  On the other hand, the second area (fine structure 102) is an area for preventing dump copy, and various dimensions of the fine structure 102 are determined so that the system breaks down when a malicious copy person performs a recording act. It is done. For example, if the dimensions of the first area are almost the same, the signals of the two are mixed and cannot be read by writing by dump copy. For example, TP2 = TP1 and PL = ML are ideal.

  Assuming illegal copying in this way, it is not necessary to consider the readability of the address pits 13 after recording (after dump copying). However, it is necessary to read the address information correctly when it is not recorded. As can be seen from FIG. 21, the pit row 15 and the address pit 13 are similar signals, and the signal output of the address pit 13 exceeding the output of the pit row 15 is required.

Therefore, the readability of the address pit 13 in the second area (surface fine structure 102) in the unrecorded state was examined for the optical disc 100 of the present invention. The signal of the address pit 13 was observed by reproducing the combined output (Ia + Ib) − (Ic + Id) using the quadrant detector 9 of FIG. FIG. 22 shows a waveform of (Ia + Ib) − (Ic + Id) reproduced through an amplifier having a bandwidth of 20 MHz or more. The pit row 13 is superimposed on the sine wave deflected track as if it were noise. The address pit 13 is synthesized with the waveform of the pit row 15 and reproduced.
Thus, if only the address pit 13 protrudes and can be detected, the address can be read. The reading performance is better when the output of the address pit 13 is larger and the leakage from the pit row 13 is smaller. Therefore, the larger the address pit aperture ratio in FIG. 22, the lower the error rate. Here, the aperture ratio in the second region is R, and its definition is
R = Δ2 / AP2
And Then, in order to obtain the correlation between the aperture ratio R and the error rate of the address pits 13, the optical disc 100 was manufactured by varying AL2 in various ways. However, the pit train was 8/16 modulation, and all the pits 15Z adjacent to the address pits 13 were aligned to 14T (synchronization signal). The error rate of the address pit 13 when not recorded was measured for the prototype disk.

  FIG. 23 shows the measured values. Here, the horizontal axis is the opening ratio R of the address pits, and the vertical axis is the block error rate measured for 100 ECC blocks or more. Note that the reliability condition is that the error rate when not recorded is less than 3%. Thus, as the value of the address pit aperture ratio R is larger, the address pits are easier to read and the error rate is smaller. In order to ensure an error rate of less than 3%, it has been found that the aperture ratio R of the address pits needs to be 0.3 or more (30% or more).

As described above, in the optical disc 100, the address pit performance that does not hinder the actual operation of the recording / reproducing drive has been studied. The above considerations can be summarized as follows. That is, the performance index of the unrecorded address pit signal has the following conditions.
First region (microstructure 101): 0.18 <APb <0.27
Second region (microstructure 102): R> 0.3
The fine dimensions satisfying the performance of the address pit signal, particularly the fine dimensions for the second region, have many parameters and are not easily specified. However, the limit range of the second area is much wider than that of the first area where it is necessary to ensure an address error rate for both recording and reproduction. Further, as described above, it is desirable that the parameters of the first area and the second area are as common as possible. Therefore, for each case, it is examined whether the restriction range of the first area can be taken in as it is. It is better to use it with partial modification. However, in many cases, it is possible to bring in the limited range of the first region almost as it is.

(Example 3)
An example in which the optical disk 100 according to one embodiment of the present invention is applied to a disk system using a red semiconductor laser will be described. Note that λ used is 650 nm, and the numerical aperture NA of the objective lens is 0.6. Therefore, the reproduction spot diameter (λ / NA) is 1083 nm (1.083 μm).

FIG. 15 shows a cross-sectional structure of an optical disc 100 that is an embodiment of the present invention. This disc is a single-sided disc and has a structure that allows recording and reproduction from one side of the disc. Microstructures 101 and 102 described later are embossed on the surface of the support 2. Further, the support 2 is an optical path from the laser to the recording layer 3, and its thickness is 0.6 mm. The material of the support 2 is a polycarbonate resin, and the refractive index n at 650 nm is 1.58. The recording layer 3 has a laminated structure mainly composed of a phase change material having a high reflectance when not recorded and a low reflectance when recording.
Specifically, the recording layer 3 is laminated by sputtering from the support 2 side in the order of ZnSSiO / AgInSbTe / ZnSSiO / AlCr. The reflectance is 18-30%. In manufacturing the disc, the manufacturing method shown in FIG. 27 was followed. Although the description of the parts common to the manufacturing method of FIG. 18 is omitted, after the recording layer 3 is formed on the support 2 (FIG. 27e), a dummy support 5 having a thickness of 0.6 mm is separately prepared (FIG. 27f). Subsequently, these two sheets were bonded together through the resin layer 4 to complete the disc (FIG. 27g). With this structure, the recording sensitivity of the recording layer 3 at 650 nm is 7.5 to 14.0 mW. Recording can also be performed with 635 nm light, and the recording sensitivity can be maintained in the range of 7.0 to 13.0 mW, which is almost the same as 650 nm.

  The fine structure at the time of non-recording is as shown in FIG. That is, the first area for recording / reproduction (microstructure 101) and the second area for preventing dump copy (microstructure 102) are alternately configured. The first area is an area (FIG. 2) in which recording / reproducing grooves 11 and address pits 13 are engraved, and the second area is an area in which dump copy prevention special pit rows 15 and address pits 13 are engraved (FIG. 2). 21). Specifically, the first region, the second region, and the first region are configured in this order from the inner periphery toward the outer periphery.

The groove 11 (width w) in the first region is spiral, and its track pitch TP is 0.74 μm, which is the same as DVD-ROM, and is sinusoidally deflected. The period of the groove 11 is recorded at a frequency eight times that of the sync frame. The wave amplitude is arbitrarily set within the range of 9 to 17 nm. Further, because of CLV (constant linear velocity) recording, the phases of adjacent tracks are random. An address pit 13 having a predetermined length AL is carved in accordance with the address value on the land outside the groove 11. Further, the depth of the groove 11 is the same as the depth of the address pit 13 and both are d.

  The special pit row 15 (width w2) in the second area is also spiral, and its track pitch TP2 is 0.74 μm, which is the same as in the first area, and is sinusoidally deflected. The groove period is recorded at a frequency eight times that of the sync frame. The wave amplitude is arbitrarily set within the range of 9 to 17 nm. Further, because of CLV (constant linear velocity) recording, the phases of adjacent tracks are random. An address pit 13 having a predetermined length AL2 is carved in accordance with the address value on the land outside the pit row 15. The depth of the pit row 15 is the same as the depth of the address pit 13 and both are d2. The special pit row 15 was 8/16 modulated, and its shortest pit length PL (3T signal) was 0.40 μm. All address pits 13 are provided with pits 15Z composed of 14T signals adjacent to each other.

  The fine structure 101 at the time of recording in the first area is as shown in FIG. The signal is recorded in the groove 11, and the recording mark 14 is an 8/16 modulated signal. The shortest mark length ML is 0.40 μm. At this time, TP (= TP2) corresponds to 68% of the reproduction spot diameter, and the length ML (= PL) of the shortest mark corresponds to 37%.

Regarding the first region, the range of the address pit output in which the interference between the recording mark 14 in the groove 11 and the address pit 13 is minimized, that is, the dimensions of various microstructures satisfying 0.18 <APb <0.27, Like Example 1, the conditions are as follows. That is, 20 nm ≦ d ≦ 41 nm, 0.35 ≦ (w / 0.74) ≦ 0.55, and 44 <35AL + d <53.
And the range of d and AL for realizing this is within the range of the parallelogram described in FIG. That is, it is a range surrounded by (d, AL) = (41, 0.08), (41, 0.34), (20, 0.94), (20, 0.68).
Subsequently, whether or not these fine dimensions can be applied to the second region is also examined. That is, with respect to the four points constituting the parallelogram, each of w2 / TP2 (= w2 / 0.74) is varied from 0.35 to 0.55 to make a prototype, and the second area aperture ratio R when unrecorded, The error rate (the block error rate when measured for 100 ECC blocks or more) was measured. The results are shown in FIG. It can be seen that when d2 = 20 nm, R = 0.45 to 0.75, and when d2 = 41 nm, R = 0.48 to 0.78. All of these values were R> 0.3, the actually measured error rate was 2.3% or less, and a sufficiently low error rate was obtained. In other words, it can be said that the fine dimensions (d2, w2, AL2) of the second region may be in the same range as that of the first region. Therefore, there is no difficulty in designing a system that performs reproduction of two areas.

Example 4
An example in which the optical disk 100 according to one embodiment of the present invention is applied to a disk system using a red semiconductor laser will be described. Note that λ used is 650 nm, and the numerical aperture NA of the objective lens is 0.6. Therefore, the reproduction spot diameter (λ / NA) is 1083 nm (1.083 μm).

  FIG. 24 shows a cross-sectional structure of an optical disc 100 that is one embodiment of the present invention. This disc is a double-sided disc and can be played from either side of the disc. That is, it is manufactured according to the manufacturing method shown in FIG. 28. First, two disk intermediates comprising the support 2 and the recording layer 3 are prepared (FIG. 28e). Then, the recording layers 3 are bonded together with the resin layer 4 so that the recording layers 3 face each other, thereby completing the disc (FIG. 28f).

  Here, fine structures 101 and 102, which will be described later, are embossed on the surface of the support 2. Further, the support 2 is an optical path from the laser to the recording layer 3, and its thickness is 0.6 mm. The material of the support 2 is a polycarbonate resin, and the refractive index n at 650 nm is 1.58. The recording layer 3 has a laminated structure mainly composed of a phase change material having a high reflectance when not recorded and a low reflectance when recording. Specifically, the recording layer 3 is laminated by sputtering from the support 2 side in the order of ZnSSiO / AgInSbTe / ZnSSiO / AlTi. The reflectance is 18-30%. With this structure, the recording sensitivity at 650 nm is 7.5 to 14.0 mW. Recording can also be performed with 635 nm light, and the recording sensitivity can be maintained in the range of 7.0 to 13.0 mW, which is almost the same as 650 nm.

  The fine structure at the time of non-recording is as shown in FIG. That is, the first area for recording / reproduction (microstructure 101) and the second area for preventing dump copy (microstructure 102) are alternately configured. The first area is an area (FIG. 2) in which recording / reproducing grooves 11 and address pits 13 are engraved, and the second area is an area in which dump copy prevention special pit rows 15 and address pits 13 are engraved (FIG. 2). 21). Specifically, the first region, the second region, and the first region are configured in this order from the inner periphery toward the outer periphery.

  The groove 11 (width w) in the first region is spiral, and its track pitch TP is 0.74 μm, which is the same as DVD-ROM, and is sinusoidally deflected. The period of the groove 11 is recorded at a frequency eight times that of the sync frame. The wave amplitude is arbitrarily set within the range of 9 to 17 nm. Further, because of CLV (constant linear velocity) recording, the phases of adjacent tracks are random. An address pit 13 having a predetermined length AL is carved in accordance with the address value on the land outside the groove 11. Further, the depth of the groove 11 is the same as the depth of the address pit 13 and both are d.

  The special pit row 15 (width w2) in the second area is also spiral in the same rotational direction as the first area, and the track pitch TP2 is 0.74 μm, the same as in the first area, and is sinusoidally deflected. . The groove period was recorded at a frequency eight times that of the sync frame, and the wave amplitude was matched with that of the first region. Note that because of CLV (constant linear velocity) recording, the phases of adjacent tracks are random. Similarly to the first area, address pits 13 having a predetermined length AL2 are carved in accordance with the address values on the lands outside the pit row 15. The depth of the pit row 15 is the same as the depth of the address pit 13 and both are d2. The special pit row 15 was 8/16 modulated, and its shortest pit length PL (3T signal) was 0.40 μm. All address pits 13 are provided with pits 15Z composed of 14T signals adjacent to each other.

In manufacturing, specific dimensions of the first region and the second region were set to 20 nm ≦ d ≦ 41 nm, 0.35 ≦ (w / 0.74) ≦ 0.55, and 44 <35AL + d <53. Further, in order to facilitate manufacture, d2 = d, w2 = w, and AL2 = AL.
Reading of the address pits 13 when the optical disk 100 manufactured in this way was not recorded was good in both the first area and the second area. Further, recording was performed on the first area as shown in FIG. That is, an 8/16 modulation signal having the shortest mark length ML of 0.40 μm was recorded in the groove 11 (record mark 14). At this time, the readability of the address pit 13 after recording was also good. Further, the recording mark 14 could be reproduced satisfactorily.

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Support body 3 Recording layer 4 Resin layer 5 Dummy support body 7 Transmission layer 9 4 division | segmentation detector 10 Fine structure 11 Groove 12 Land 13 Address pit 14 Information mark 15 Copy prevention pit row | line | column 15Z For copy prevention adjacent to an address pit Pit 20 Fine structure 21 Groove 22 Land 23 Address pit 24 Address area 100 Optical disc 101 Fine structure of the first area 102 Fine structure of the second area

Claims (2)

A first region having a fine structure comprising a sine wave deflection groove, a first land, and a first address pit having a predetermined length distributed in the first land, and a sine wave deflection pit A support having a row, a second land, and a second region having a fine structure composed of second address pits having a predetermined length distributed in the second land, and the fine At least a recording layer having a reflectance of 18 to 30% including a rewritable phase change material formed on the structure, and an adhesive resin layer formed on the recording layer, and the sine of the recording layer By varying the length of the recording mark on the wave deflection groove, the recording mark having a readable reflectance that is lower than the reflectance of the recording layer is modulated and recorded. But, With live wavelength lambda, an optical information recording medium to be reproduced by the 4-division detector,
The phase change material is a phase change material having a high reflectance when not recorded and a low reflectance after recording,
The quadrant detector has four regions divided by a straight line in the radial direction of the optical information recording medium and a straight line in the tangential direction orthogonal to the radial direction, and the divided by the straight line in the tangential direction. The difference between the first combined output value output from the two areas on the inner peripheral side of the optical information recording medium and the second combined output value output from the two areas on the outer peripheral side of the optical information recording medium When the peak signal output value of the first address pit observed by the output value is divided by the total synthesized output value output from the four areas of the four-divided detector, the range of 0.18 to 0.27 The refractive index of the support, the track pitch of the sine wave deflection groove, the depth of the sine wave deflection groove and the first address pit, the width of the sine wave deflection groove, the first address pit Length, with determining the shortest mark length of the recording mark,
The track pitch of the sine wave deflection pit row is the same as the track pitch of the sine wave deflection groove,
The shortest pit length and the shortest mark length of the sine wave deflection pit row are the same,
An optical information recording medium having a refractive index of 1.45 to 1.65 at the reproduction wavelength λ. The reproduction wavelength λ is 650 nm,
2. The optical information recording medium according to claim 1, wherein a refractive index of the support at the reproduction wavelength λ is 1.58.

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