JP4040563B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus of an optical disc having tracking lands / grooves and capable of recording both grooves / lands, and more particularly to an optical disc apparatus capable of accurately reading address information in the lands and grooves.

  In recent years, there has been a demand for higher density for optical discs, and various methods have been proposed in order to meet this demand. As one of such systems, land / groove recording is being studied. This land / groove recording is a method of recording on both the land and the groove formed on the optical disc. In this case, it is necessary to record the address on both the land and the groove. As address information recording methods, for example, methods described in Patent Document 1 and Patent Document 2 described below have been proposed.

  FIG. 13 is a diagram for explaining the address signal detection method described in Patent Document 1. In FIG. As shown in FIG. 13, in this method, only one side wall (1a in the figure) of the groove is meandered according to the address. Then, address information is obtained by detecting the meandering frequency of the meandering side wall 1a from the tracking error signal using a light spot smaller than twice the groove width (land width).

In the address signal detection method described in Patent Document 2, the groove width (land width) is changed in accordance with the address signal in the address recording area. Then, the address signal is reproduced by utilizing the fact that the total light amount of the reflected light from the optical disk changes according to the groove width (land width).
JP-A-5-314538 JP-A-6-301976

  However, the conventional optical disc described in Patent Document 1 has a problem that the information reproduction signal is deteriorated because the reflectivity changes due to the land and groove widths being different depending on the location. In addition, although information recording at a very high density is possible, since the land and groove widths differ depending on the location, there is a problem that a track offset tends to occur in the beam spot and affects the reproduction signal.

  Further, in the optical disk disclosed in Patent Document 2, the address signal is reproduced with the total light quantity, but the threshold value of the total light quantity is easily influenced by the fluctuation of the laser light quantity, the fluctuation of the groove width, the difference in reflectivity for each disk, and the like. Therefore, the system for preventing it becomes complicated.

  Furthermore, in the above two conventional examples, both the land and the groove are not constant in width, and thus there is a problem that manufacture is difficult.

  The present invention has been made to solve the above problems, and provides an optical disc apparatus for an optical disc that can reliably give an address signal to a groove and a land and can give a high-quality information reproduction signal. The purpose is to provide.

An optical disc apparatus according to the present invention is an optical disc having a recording track consisting of a groove and a land, and an address area having the same angular position as the head of an adjacent recording track is formed on at least a part of the recording track, The first recording track, which is one of the groove and the land, has both side walls meandering according to address information in the address area and is formed to have substantially the same width, and according to the address information. Among the meandering portions, meandering portions corresponding to the respective bits of the address information are synchronized between the first recording tracks adjacent to each other, and the synchronized meandering portions are identical to each other when viewed from the address reproducing system. An optical disc apparatus for reproducing information from an optical disc having a length, wherein the light beam follows the first recording track When and, by detecting the meandering of the side wall, is characterized by comprising a first address reproducing means for reproducing address information in the first recording track.
In the optical disk apparatus according to the present invention, in the optical disk apparatus described above, the first address reproducing means detects meandering of a side wall from a tracking signal, and the optical beam is made to follow the first recording track or adjacent thereto. Whether to follow the second recording track sandwiched between the two first recording tracks is selected by inverting the polarity of the tracking signal.
The optical disk apparatus according to the present invention is characterized in that, in the optical disk apparatus described above, the first address reproducing means detects a meander of a side wall from a tracking signal, and the tracking signal is obtained by a push-pull method. .
The optical disc apparatus according to the present invention has a recording track composed of a groove and a land, and an address area starting at the same angular position as an adjacent recording track is formed on at least a part of the recording track. The first recording track, which is one of the lands, is an optical disc apparatus for reproducing information from an optical disc in which both side walls meander in accordance with address information and are formed to have substantially the same width in the address area. When the light beam follows the first recording track, the first address reproducing means for reproducing the address information in the first recording track by detecting the meandering of the side wall, and the light beam are adjacent to each other. When following a second recording track sandwiched between two first recording tracks, the shapes of the side walls on both sides are different. Detecting means for detecting a difference unit which are based on the detection result of the detection means, and a second address reproducing means for reproducing the address information of the second recording track, to become a features.

The optical disc apparatus according to the present invention has a recording track composed of a groove and a land, and an address area starting at the same angular position as an adjacent recording track is formed on at least a part of the recording track. The first recording track, which is one of the lands, has both side walls meandering according to the address information in the address area and is formed to have substantially the same width. The address information recorded on the first recording track is An optical disc apparatus for reproducing information from an optical disc composed of a Gray code that differs in only one bit from the address information recorded in the adjacent first recording track, when the light beam follows the first recording track In addition, by detecting the meandering of the side wall, the first address information is reproduced from the first recording track. A dress reproducing means and a detecting means for detecting a different portion in which the shape of the side wall on both sides thereof is different when the light beam follows a second recording track sandwiched between two adjacent first recording tracks. And second address reproducing means for reproducing address information of the second recording track based on the detection result of the detecting means.

The optical disc apparatus according to the present invention is the optical disc apparatus according to the above , wherein the detecting means follows that the light beam follows a second recording track sandwiched between two adjacent first recording tracks. In addition, it is characterized in that a difference portion in which the shape of the side wall on both sides of the second recording track is different is detected by detecting the change location of the total signal depending on the amount of light reflected from the optical disc.

The optical disk apparatus according to the present invention is the optical disk apparatus according to the above , wherein the second address reproducing means meanders the side wall at the matching part other than the different part when the light beam follows the second recording track. A matching part signal detection means for obtaining a matching part signal based on the above, and adding the signals in the different part to the matching part signal assuming that the signals in the different part are "0" and "1", thereby generating at least two hypothetical signals And synthesizing means for selecting one of the at least two hypothetical signals based on a predetermined rule and using it as address information of the second recording track.

The optical disc apparatus according to the present invention is determined as a reading error in the optical disc apparatus described above, when two of the at least two hypothetical signals are not address information of two adjacent first recording tracks. The first error detecting means is provided.

The optical disc apparatus according to the present invention is the above- described optical disc apparatus, wherein the second error detection is performed to determine a reading error when the number of the different parts existing in one second recording track does not match a predetermined value. It is characterized by having a means.

  In the optical disk apparatus of the present invention, since the different portions where the meandering states of the side walls on both sides are different are detected, it is possible to accurately reproduce the address information of the land or groove.

  Further, the address signal can be easily reproduced by using the gray code as the address information.

  Also, assuming that the signals in the different parts are “0” and “1”, two hypothetical signals are generated, and the recording tracks whose addresses are defined by the hypothetical signals are the same type of recording tracks (land or If the reading error of the address information is detected depending on whether or not it is a groove), the reliability of the reproduced address information can be improved.

  If the reading error of the address information is detected based on the number of different parts, the reliability of the reproduced address information can be improved.

[Embodiment 1]
An embodiment of the optical disk substrate according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a plan view of an optical disk substrate according to the present embodiment, FIG. 2 is a sectional view in the radial direction, and a tracking groove 1 (first recording track in claims) and a land 2 (in claims) A second recording track) is formed. The width of the land 2 is set to be approximately equal to the width of the groove 1.

  In the optical disk of the present embodiment, in the first area (address area in the claims) for obtaining address information, both side walls of the groove 1 (first groove a, second groove b in FIG. 1) are address information. Accordingly, the optical disk substrate 5 meanders in the radial direction. The first area of each groove has the same start position as that of at least one of the adjacent grooves (for example, when information is recorded by the ZCAV method, the first area is in the same radius area (zone)). The start position of the first region of the groove to which the groove belongs is on the same line segment connecting the center and the outer periphery of the disc). In adjacent grooves 1, meandering portions corresponding to the same bits of address information are formed synchronously (with the same length as viewed from the address reproduction system) (that is, on the side walls of adjacent grooves 1). The meander is formed based on a synchronized reference clock).

  The meander frequency is set higher than the tracking frequency of the tracking servo system. For this reason, the light beam does not follow the meandering of the side wall, but scans substantially the center of the groove 1 or land 2 (first land a). The second area is an area where information is recorded, reproduced or erased. Grooves 1 are formed with substantially the same width through the first region and the second region.

  Whether the recording / reproducing light spot 4 follows the groove 1 or the land 2 can be easily selected by inverting the polarity of the tracking signal. The tracking signal is obtained by a push-pull method, for example.

  In such an optical disc, in order to read the address information recorded from the land 1 and the groove 2, the meandering state of the side walls in the land 1 and the groove 2 may be detected. In order to secure a signal component for obtaining address information, the meandering amplitude may be ± 5 nm or more. Increasing the amount of amplitude increases the amount of signal, but makes it difficult to produce. From the viewpoint of production, it is preferable to set a range of ± 10 nm to ± 50 nm.

  Hereinafter, the address information reproducing method according to the present embodiment will be described in detail with reference to FIG. In FIG. 1, in the first area, the first groove a meanders in the radial direction of the optical disk substrate 5 while maintaining substantially the same width in accordance with the address information modulated into the gray code corresponding to (1001). The second groove b meanders in the radial direction of the optical disk substrate 5 while maintaining substantially the same width according to the address information modulated into the gray code corresponding to (1011). Needless to say, the swing directions of the information “0” and “1” in FIG. 1 may be reversed.

  First, a method for reproducing address information from the groove 1 in such an optical disc will be described.

  As described above, the recording / reproducing light spot 4 scans substantially the center position of the first groove a and the second groove b, and reproduces address information during this scanning. In the first region, since the side walls of the first groove a and the second groove b meander, the positional relationship between the recording / reproducing light spot 4 and the first groove a and the second groove b changes, and accordingly tracking is performed. The error signal changes. That is, when the side walls of the first groove a and the second groove b meander to the inner peripheral side, the recording / reproducing light spot 4 is relatively shifted to the outer peripheral side (the tracking error signal is recorded on the recording / reproducing light spot 4). Is a signal indicating that the position is shifted to the outer peripheral side). When the side walls of the first groove a and the second groove b meander to the outer peripheral side, the recording / reproducing light spot 4 is relatively shifted to the inner peripheral side (the tracking error signal is recorded on the recording / reproducing light spot 4). Is a signal indicating that the position has shifted to the inner circumference side). Therefore, if the tracking error signal is monitored, the meandering state of the groove 1 (the first groove a and the second groove b) can be detected, and the address information recorded there can be reproduced.

  3 (1) and 3 (3) are schematic diagrams of tracking error signals in the first groove a and the second groove b in FIG. 1, respectively. As shown in this figure, the level of the tracking error signal changes between H and L as the side walls meander to the inner or outer peripheral side of the optical disc. Therefore, by detecting the change in the tracking error signal, it is possible to obtain the address information of (1001) from the first groove a and (1011) from the second groove b.

  Next, a method for reproducing address information from the land 2 will be described. In this case, since the side walls on both sides of the first land a meander in the same direction at the y portion in the first region (the matching portion in the claims), the meander is detected in the same manner as in the case of the groove 1. be able to. However, in the x part (the different part in the claims), the side wall of the land a meanders in different directions on both sides, and the state of the tracking error signal is different here. Specifically, in the portion x in FIG. 1, since both side walls meander in the direction of narrowing the width of the first land a, the first land a in this portion is an abbreviation of the recording / reproducing light spot 4. It will be located in the center. Therefore, the tracking error signal in the x portion is a signal indicating that there is no positional deviation.

  FIG. 3B is a schematic diagram showing a tracking error signal from the first land a. As shown in this figure, in the portion x, the level of the tracking error signal is different from other portions (portions where the side walls on both sides are meandering in the same manner), and the intermediate level M between H and L described above. It becomes. This intermediate level M can be detected by ternary detection or the like, whereby the x portion can be detected.

  In the optical disk apparatus according to the present embodiment, the address information is reproduced from the land 2 based on the detection result of the x part. For example, it is performed as follows.

  When the x part is detected, the signal at the x part is assumed to be “0” and “1” and added to the signal obtained from the y part ((10X1) in FIG. 1, X is a signal at the x part). Thus, two hypothetical signals ((1001) and (1011)) are obtained. Since these two hypothetical signals must be the address information of the two grooves a and b adjacent to the first land a, the address information of the land 2 is adjacent to the inner circumference side, for example. If the same signal as the address information of the groove 1 is determined, the address information of the inner peripheral side of the groove 1 having the two address information can be selected and used as the address information of the land 2. In the case of FIG. 1, since there is only one x part, the address information can be easily generated as described above. However, when there are a plurality of x parts, it is necessary to perform complicated processing.

  In this example, the land 2 has the same address information as that of the adjacent groove 1, but even if the land 2 and the groove 1 are set to the same address information in this way, the light depends on the polarity of the tracking error signal. Since it is possible to determine whether the beam is scanning the land 2 or the groove 1, it is possible to accurately specify the track according to the determination result.

  As described above, in the optical disc of the present embodiment, the start position of the area where the address information is recorded is at the same angular position as the adjacent track, and the address information is the same in the two adjacent grooves. Since the meandering portion corresponding to 1 bit is formed synchronously, the address information recorded in the two grooves 1 existing on both sides of the land 2 when the recording / reproducing light spot scans the land 2. Can be detected, and based on this, the address information of the land 2 can be reproduced. Accordingly, the address information can be accurately obtained from both the land 2 and the groove 1, and based on this, processing such as reproduction and recording can be performed.

  The reproduction of the address information from the land 1 is not limited to the above method. For example, a signal obtained by ternary detection (in the case of FIG. 3 (2), a signal (HLMH)) is directly used as an address signal. The track address may be determined based on the ternary signal. In addition, an address signal may be generated based on the position where the intermediate level M exists (the position where the x portion exists).

  Further, the detection of the x portion is not limited to the above method. For example, the detection can be performed using a total signal that depends on the amount of light reflected from the optical disk. This is because the width of the land 2 is substantially constant in a portion other than the x portion, and the reflected light amount is substantially constant regardless of the presence or absence of meandering. In the x portion, the width of the land increases and decreases, and the reflected light amount changes. is there. In the case of FIG. 1, the total signal is as shown in FIG. 3 (4), and the x part can be detected by detecting the change. Accordingly, even if the above three-value detection is not performed, the tracking error signal H (or L) is discriminated (other than H (or L) is regarded as L (or H)) and the change location of the total signal is detected. Only the address information can be reproduced.

  In the example of FIG. 1, the address information of groove 1 is composed of a gray code that differs from adjacent groove 1 only by one bit. By doing so, there is only one x part in each land 2 described above, and the detection becomes simple and accurate.

  Next, a method for detecting an address information reading error in the optical disc as described above will be described.

  As shown in FIG. 1, when the address information is composed of a gray code, there is always one x part (different part) in each land 2. For this reason, an address reading error can be determined when two or more x portions are detected or not detected. Of course, this error detection is not effective only when there is only one x part, and can be applied when the number of x parts is predetermined. That is, when the number of x portions is other than the predetermined number, it can be determined as a reading error.

  As described above, when the address information of the land 2 is the same as the address information of the adjacent groove 1, the signals obtained when the signals of the x part are assumed to be “0” and “1” are adjacent. If the address information of the two grooves 1 is not obtained, it can be determined that an address reading error has occurred.

  By performing such error detection, the reliability of the address information can be improved.

  Further, in the optical disk substrate 5 of the present embodiment, accurate address information can be obtained by making the diameter of the recording / reproducing light spot 4 larger than the track pitch and smaller than twice the track pitch.

  As described above, in the optical disk and the optical disk apparatus according to the present embodiment, the address information can be reproduced by the tracking error signal. . Further, since the meandering shape is curved as shown in FIG. 1, high-frequency noise is less likely to occur when address information is read from the meandering portion (first region), and the address information is reliably read out. It becomes possible. This is very important when address information is recorded only in a part as in the present application.

  Next, a manufacturing process of the optical disk substrate 5 will be described with reference to FIGS. 4 (a) to 4 (e).

  (A) A photoresist 6 is applied to one side of the glass substrate 5.

  (B) The laser beam is condensed on the photoresist 6 by the objective lens 7, and the photoresist 6 is exposed to a desired groove 1 pattern.

  (C) The exposed photoresist 6 is removed by development, and a desired pattern is formed from the remaining photoresist 6.

  (D) The glass substrate 5 and the photoresist 6 are etched by dry etching or wet etching to form a desired pattern on the glass substrate 5.

  (E) The remaining photoresist is removed by ashing.

  FIG. 5 shows an apparatus for exposing the photoresist 6 to the groove 1 pattern. As shown in FIG. 5, a laser light source 11a for exposing the photoresist 6 and a focus laser light source 11b for the objective lens 7 are provided. For example, an Ar laser is used as the laser light source 11a, and the laser light source 11b is used. For example, a He—Ne laser is used.

  The laser light from the laser light source 11 a is reflected by the mirrors 19 and 20 after entering the light modulator 22 after optical noise is reduced by the noise suppression device 12 a. As the optical modulator 22, for example, an acousto-optic element can be used. In this case, the focusing lens 21 is disposed before and after the optical modulator 22.

  The laser light that has passed through the optical modulator 22 enters the optical deflector 23. As the optical deflector 23, for example, an electro-optic element or an acousto-optic element can be used, and the traveling direction of the laser beam can be changed.

  Further, the laser beam is enlarged to an appropriate beam diameter by the beam expander 24 and is incident on the objective lens 7 by the two-color mirror 15. Then, the light is focused on the photoresist 6 on the glass substrate 5 as a photosensitive light spot by the objective lens 7.

  The light modulator 22, the light deflector 23, and the beam expander 24 are controlled by drivers 25, 26, and 27, respectively.

  On the other hand, the laser light from the laser light source 11b is reduced in optical noise by the noise suppression device 12b, passes through the polarizing beam splitter 13, the (1/4) wavelength plate 14, and the two-color mirror 15, and is made into glass by the objective lens 7. The light is focused on the photoresist 6 on the substrate 5.

  The reflected light is condensed again by the objective lens 7, passes through the two-color mirror 15, the (¼) wavelength plate 14, and the polarization beam splitter 13, and is condensed on the photodetector 18 by the objective lens 16 and the cylindrical lens 17. Is done. Based on the signal from the light detector 18, the focus servo system drives the objective lens 7 in the focus direction, and the objective lens 7 is focused on the photoresist 6 on the glass substrate 5 rotated by the spindle motor.

  In the above configuration, the light beam spot is first positioned. That is, the magnitude of the DC voltage applied to the optical deflector 23 is adjusted by the driver 26. Thereafter, a voltage obtained by superimposing the signal voltage corresponding to the meandering on the DC voltage is applied to the optical deflector 23 by the driver 26 only in the meandering area according to the address information of the groove 1. Thereby, the area | region where the groove | channel 1 meanders according to address information can be formed.

  Further, the manufacturing method is not limited to the present embodiment, and it is possible to manufacture using two beams, and is not limited to these manufacturing methods.

  Further, the optical disk substrate 5 of the present embodiment is not limited to the above, but is made of a plastic resin by injection molding or injection compression molding using a stamper created by the processes of FIGS. 6 (a) to 6 (f). It may be a thing.

  (A) A photoresist 6 is applied to one side of the glass substrate 5.

  (B) The laser beam is condensed on the photoresist 6 by the objective lens 7, and the photoresist 6 is exposed to a desired groove 1 pattern.

  (C) The exposed photoresist 6 is removed by development, and a desired pattern is formed from the remaining photoresist 6.

  (D) A conductive thin film 8 is formed on the pattern made of the photoresist 6 by sputtering or electroless plating.

  (E) A metal layer 9 is formed on the thin film 8 by electroforming or the like.

  (F) The thin film 8 and the metal layer 9 are peeled from the glass substrate 5 and the photoresist 6.

  The material of the thin film 8 is Ni, Ta, Cr or an alloy thereof, or a composite film thereof. The material of the metal layer 9 is Ni, Ta, Cr, an alloy thereof, or a composite film thereof. Used.

  The thin film 8 and the metal layer 9 peeled off in the step (f) are called a stamper 10, and the optical disk substrate 5 made of plastic is manufactured by injection molding or injection compression molding using the stamper 10. As the plastic material, a thermoplastic resin such as polycarbonate resin, acrylic resin, ethylene resin, ester resin, nylon resin, or APO is used.

  In addition, the manufacturing method of the stamper 10 according to the present embodiment is not limited to the above, and a mask master disk in which the side walls of the grooves meander according to address information may be created and manufactured using the mask master disk.

  Further, the material and manufacturing method of the optical disk substrate 5 are not limited to those described above.

  In the optical disk of the present embodiment, the width of one of the land and the groove is substantially constant, so that it can be manufactured with one laser beam, is easy to manufacture, and is very Precise manufacturing is possible.

[Embodiment 2]
The following will describe another embodiment of the optical disk substrate of the present invention with reference to FIGS.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiment 1], and has a different groove shape based on address information.

  The groove shape according to the present embodiment is shown in FIG. A tracking groove 1 and a land 2 are formed on the substrate 5. The width of the land 2 is set to be approximately equal to the width of the groove 1.

  Both side walls of the groove are swung to both the inner and outer peripheral sides of the optical disk substrate 5 according to address information “1”, and the frequency of the wobbling is set higher than the tracking frequency of the tracking servo system. ing.

  Thus, detection of address information from the groove 1 or land 2 meandering the side wall can be performed in substantially the same manner as in [Embodiment 1]. However, in this embodiment, the recording / reproducing light spot is the groove 1 or land 2. Address information is generated on the basis of a signal obtained by differentiating the tracking error signal during scanning. The differentiated signal waveform is the same as the signal waveform schematically shown in FIG.

  In the meandering shape as shown in FIG. 7, it is not necessary to change the meandering frequency at the time of manufacturing, and the control mechanism of the manufacturing apparatus can be simplified.

[Embodiment 3]
The following will describe another embodiment of the optical disk substrate of the present invention with reference to FIGS.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiment 1], and has a different groove shape based on address information. .

  The groove shape according to the present embodiment is shown in FIG. A tracking groove 1 and a land 2 are formed on the substrate 5. The width of the land 2 is set to be approximately equal to the width of the groove 1. Both side walls of the groove have a shape that returns to the original after swinging toward the inner peripheral side (or outer peripheral side) of the optical disk substrate 5 in accordance with “1” of the address information, and the meandering frequency is the tracking frequency of the tracking servo system. Is set higher than. Of course, it may swing in the opposite direction.

  By adopting such a shape, since the meandering shape is simple, the reproduction signal can be easily detected.

  In the above [Embodiments 1 to 3], the meandering shape of the side walls is curved, but it goes without saying that it may be rectangular.

[Embodiment 4]
Another embodiment of the optical disk of the present invention will be described below with reference to FIG.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiments 1 to 3], and the groove portion and the land portion are reversed. In this way, both side walls of the land are meandered. That is, the land address information is read as it is, and the groove address information is reproduced by combining the address information from adjacent land portions. The reproduction method may be the same as described in [Embodiments 1 to 3].

[Embodiment 5]
The following will describe another embodiment of the optical disk of the present invention with reference to FIG.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiment 1] to [Embodiment 3], and has a groove depth (land height). Is different).

  The groove depth (land height) of the optical disk substrate 5 is in the vicinity of λ / 6n [refractive index of substrate: n, recording wavelength: λ], and the groove depth (land height) can be changed. The etching ratio is changed, the etching conditions are changed, the groove depth (land height) of the stamper 10 is set near λ / 6n, or the molding conditions are changed.

  If the groove depth (land height) of the optical disk substrate 5 is in the vicinity of λ / 6n, crosstalk between tracks (around noise from adjacent track signals) can be reduced, and high density can be achieved.

[Embodiment 6]
The following will describe another embodiment of the optical disk of the present invention with reference to FIG.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiment 1] to [Embodiment 3], and has a groove depth (land height). Is different).

  The groove depth (land height) of the optical disk substrate 5 is in the vicinity of λ / 8n [the refractive index of the substrate: n, the recording wavelength: λ], and the groove depth (land height) can be changed. The etching ratio is changed, the etching conditions are changed, the groove depth (land height) of the stamper 10 is set near λ / 8n, or the molding conditions are changed.

  When the groove depth (land height) of the optical disk substrate 5 is in the vicinity of λ / 8n, the tracking signal becomes maximum and stable track following is possible.

[Embodiment 7]
The following will describe another embodiment of the optical disk of the present invention with reference to FIG.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiment 1] to [Embodiment 3], and has a groove depth (land height). Is different).

  The groove depth (land height) of the optical disk substrate 5 is in the vicinity of λ / 10n [the refractive index of the substrate: n, the recording wavelength: λ], and the groove depth (land height) can be changed. The etching ratio is changed, the etching conditions are changed, the groove depth (land height) of the stamper 10 is set in the vicinity of λ / 10n, or the molding conditions are changed.

  When the groove depth (land height) of the optical disk substrate 5 is in the vicinity of λ / 10n, the reproduction signal becomes large and stable reproduction signal characteristics can be obtained.

[Embodiment 8]
Another embodiment of the optical disk of the present invention will be described below with reference to FIG.

  The optical disk substrate 5 used in the present embodiment has the same characteristics, substrate material, and manufacturing process as the optical disk substrate 5 of [Embodiment 1] to [Embodiment 3], and has a groove depth (land height). Is different).

  The groove depth (land height) of the optical disk substrate 5 is λ / 3n or more [refractive index of the substrate: n, recording wavelength: λ], and the groove depth (land height) can be changed. The etching ratio is changed, the etching conditions are changed, the groove depth (land height) of the stamper 10 is set to λ / 3n or more, or the molding conditions are changed.

  If the groove depth (land height) of the optical disk substrate 5 is λ / 3n or more, even when the intensity of light beam irradiation is high, cross erase (erasely erases the recorded information in the adjacent track when erasing information). ), The intensity control of the light beam becomes easy, and a stable erasing operation can be performed.

[Embodiment 9]
The embodiment of the optical disk of the present invention will be described below with reference to FIG.

  In the optical disk of the present embodiment, as shown in FIG. 10, a magneto-optical recording layer 28a and an overcoat layer 29 are sequentially formed on the optical disk substrate 5 of [Embodiment 1] to [Embodiment 8]. It is configured. Although not shown, the magneto-optical recording layer 28a includes a light-transmitting dielectric layer, a magnetic layer, a protective layer, and a reflective layer. The magnetic layer is, for example, DyFeCo, TbFeCo, DyTbFeCo. , GdTbFe, GdTbFeCo and other rare earth metal-transition metal alloys. The magnetic layer exhibits the property of perpendicular magnetization from room temperature to the Curie point.

  When recording in the above configuration, the temperature of the magnetic layer is raised to near the Curie point by irradiating laser light so that the magnetization of the magnetic layer is zero or reversed by the recording magnetic field, for example, upward recording By applying a magnetic field, the magnetization of the magnetic layer is aligned upward, and then the laser beam is also irradiated to raise the temperature of the magnetic layer to near the Curie point, and the magnetization of the magnetic layer is reversed to zero or by a recording magnetic field. Recording is performed by aligning the magnetization of the magnetic layer downward by applying a downward recording magnetic field (opposite direction) in such a state.

  Actually, there are a light modulation recording method for modulating a laser beam and a magnetic field modulation recording method for modulating a recording magnetic field.

  As a result, a magneto-optical disk which is an optical disk that can be rewritten over 1 million times is obtained.

  Further, the magnetic layer is not limited to a single layer but may be a multilayer film. In the case of a multilayer film, an overwrite function or the like can be added, and higher performance can be achieved.

[Embodiment 10]
An embodiment of the optical disk of the present invention will be described below with reference to FIG.

  As shown in FIG. 11, the optical disk of the present embodiment has a phase change recording layer 28b and an overcoat layer 29 on the optical disk substrate 5 described in [Embodiment 1] to [Embodiment 8]. The structure is formed sequentially. Although not shown, the phase change recording layer 28b includes a light-transmitting dielectric layer, a recording layer, a protective layer, and a reflective layer. The recording layer is, for example, a phase such as GeSbTe. Made of changeable recording material.

  When recording is performed in the above configuration, recording is performed by irradiating the high power laser light to make the recording layer amorphous, and irradiating the low power laser light to make the recording layer crystalline.

  As a result, a phase-change optical disk, which is an optical disk that can be rewritten only by laser light, is obtained.

[Embodiment 11]
Embodiment 11 of the optical disk of the present invention will be described with reference to FIG.

  As shown in FIG. 9, the optical disk of the present embodiment has a magneto-optical recording layer 28c and an overcoat layer 29 sequentially formed on the optical disk substrate 5 described in [Embodiment 1] to [Embodiment 8]. It has a formed configuration. Although not shown, the magneto-optical recording layer 28c includes a light-transmitting dielectric layer, a reproducing magnetic layer, a recording magnetic layer, and a protective layer. The reproducing magnetic layer includes, for example, GdFeCo, The rare earth metal-transition metal alloy such as GdDyFeCo and the recording magnetic layer are made of a rare earth metal-transition metal alloy such as DyFeCo, TbFeCo, DyTbFeCo, GdTbFe, GdTbFeCo, for example.

  The reproducing magnetic layer exhibits in-plane magnetization from room temperature to a predetermined temperature and exhibits a characteristic of perpendicular magnetization from the predetermined temperature, and the recording magnetic layer exhibits a characteristic of perpendicular magnetization from a room temperature to a Curie point.

  When recording is performed in the above configuration, it is the same as [Embodiment 10], and reproduction is performed as follows. When the reproducing magnetic layer is irradiated with the light beam, the temperature distribution of the irradiated portion becomes a Gaussian distribution, so that only the temperature smaller than the diameter of the light beam rises. As the temperature rises, the magnetization at the temperature rise portion shifts from in-plane magnetization to perpendicular magnetization. That is, the direction of magnetization of the recording magnetic layer is transferred to the reproducing magnetic layer by exchange coupling between the reproducing magnetic layer and the recording magnetic layer. When the temperature rise portion shifts from in-plane magnetization to perpendicular magnetization, only the temperature rise portion shows a magneto-optic effect, and information recorded on the recording magnetic layer is reproduced based on the reflected light from the temperature rise portion. .

  When the light beam moves and the next recording bit is reproduced, the temperature of the previous reproducing portion is lowered and the perpendicular magnetization is shifted to the in-plane magnetization. Along with this, the temperature-decreasing portion does not show the magneto-optical effect, and the magnetization recorded in the recording magnetic layer is masked by the in-plane magnetization of the reproducing magnetic layer and cannot be reproduced. Thereby, a signal from an adjacent bit that causes noise is not mixed.

  As described above, since only the region having a temperature equal to or higher than the predetermined temperature is involved in reproduction, a recording bit smaller than the diameter of the light beam can be reproduced, and the recording density is remarkably improved.

  In addition, a non-magnetic layer made of a dielectric multilayer or a metal layer is formed between the reproducing magnetic layer and the recording magnetic layer, and the reproducing magnetic layer may be reproduced using a leakage magnetic field from the recording magnetism during reproduction. . Further, a reflective layer or a protective layer may be provided after the protective layer.

  As described above, the optical disc according to the present invention has a recording track composed of a groove and a land, and an address area starting at the same angular position as the adjacent recording track is formed on at least a part of the recording track. A first recording track that is one of the groove and the land is an optical disc, and both side walls meander in accordance with address information and are formed to have substantially the same width in the address area, The meandering portion corresponding to each bit of the address information is formed in synchronism between adjacent first recording tracks.

  In the optical disc, the side walls on both sides of either the recording track of the groove or the land meander according to the address information, and the meandering portion corresponding to each bit of the address information is synchronized with at least one adjacent recording track. Therefore, the difference in address information between two adjacent recording tracks can be detected, and by using this detection result, the address information can be accurately obtained from both the land and the groove. Moreover, since the width of either the groove or the land is substantially constant, the manufacturing is easy.

  Further, in addition to the above configuration, the optical disc includes that the address information recorded on the first recording track is composed of a gray code that is different from the address information recorded on the adjacent first recording track only by one bit. It may be a feature. By making the address information gray code, the address signal can be easily reproduced.

  Further, in addition to the above configuration, the groove depth of the optical disk may be set in the vicinity of λ / 6n [refractive index of substrate: n, recording wavelength: λ]. By setting the groove depth in the vicinity of λ / 6n, crosstalk between tracks can be reduced, and high-density recording becomes possible.

  In addition to the above configuration, the groove depth of the optical disk may be set in the vicinity of λ / 8n [refractive index of substrate: n, recording wavelength: λ]. By setting the groove depth in the vicinity of λ / 8n, the tracking signal is maximized and stable track following is possible.

  Further, in addition to the above configuration, the groove depth of the optical disk may be set in the vicinity of λ / 10n [refractive index of substrate: n, recording wavelength: λ]. By setting the groove depth in the vicinity of λ / 10n, the reproduction signal is maximized and stable reproduction signal characteristics can be obtained.

  In addition to the above configuration, the groove depth of the optical disk may be set to λ / 3n or more [refractive index of substrate: n, recording wavelength: λ]. By setting the groove depth to λ / 3n or more, even when the irradiation intensity of the light beam is strong, there is no cross erase (the recorded information in the adjacent track is erased accidentally when erasing information), and the light The beam intensity can be easily controlled, and a stable erase operation can be performed.

  The optical disc apparatus according to the present invention is a first recording track in the optical disc apparatus for reproducing information from the optical disc by detecting meandering of the side wall when the light beam follows the first recording track. 1 is provided with first address reproducing means for reproducing the address information.

  Further, in addition to the above configuration, the optical disc apparatus has different side wall shapes when the light beam follows the second recording track sandwiched between two adjacent first recording tracks. Detection means for detecting a different portion, and second address reproduction means for reproducing address information of the second recording track based on a detection result of the detection means. In the optical disc apparatus, since the different portions where the meandering states of the side walls on both sides are different are detected, the address information of the land or groove can be accurately reproduced.

  Further, in addition to the above configuration, the optical disk apparatus may be configured such that the second address reproducing means is based on meandering of the side wall at the matching portion other than the different portion when the light beam follows the second recording track. At least two hypothetical signals are generated by matching unit signal detection means for obtaining a coincidence unit signal and adding the signals in the different unit to the coincidence unit signal assuming “0” and “1”. And synthesizing means for selecting one of the at least two hypothetical signals based on the set rule and making it the address information of the second recording track. Assuming that the signals in the different portions are “0” and “1”, two hypothetical signals are generated, and the recording tracks (lands or grooves) of the same type in which the recording tracks whose addresses are defined by the hypothetical signals are adjacent to each other. If the reading error of the address information is detected depending on whether or not it is, the reliability of the reproduced address information can be improved.

  Further, in addition to the above configuration, the optical disc apparatus may include a first error that is determined as a reading error when two of the at least two hypothetical signals are not address information of two adjacent first recording tracks. You may have a detection means.

  In addition to the above configuration, the optical disc apparatus further includes second error detection means for determining a reading error when the number of the different parts existing in one second recording track does not match a predetermined value. You may do it. If the reading error of the address information is detected based on the number of different parts, the reliability of the reproduced address information can be improved.

It is a schematic top view schematically showing an example of the configuration of the optical disk substrate of the present invention. It is a cross-sectional schematic diagram which shows one structural example of the optical disk substrate of this invention. It is a schematic diagram showing the reproduction signal from the optical disk substrate of the present invention. It is explanatory drawing which shows the manufacturing process of the optical disk board | substrate of FIG. It is explanatory drawing which shows the manufacturing apparatus of the optical disk board | substrate of FIG. It is explanatory drawing which shows the other manufacturing process of the optical disk board | substrate of FIG. It is a schematic upper surface schematic diagram which shows the other structural example of the optical disk board | substrate of this invention. It is a schematic upper surface schematic diagram which shows the other structural example of the optical disk board | substrate of this invention. It is a schematic upper surface schematic diagram which shows the other structural example of the optical disk board | substrate of this invention. It is a cross-sectional schematic diagram which shows the structure of the other optical disk using the optical disk board | substrate of this invention. It is a cross-sectional schematic diagram which shows the structure of the other optical disk using the optical disk board | substrate of this invention. It is a cross-sectional schematic diagram which shows the structure of the other optical disk using the optical disk board | substrate of this invention. It is a schematic upper surface schematic diagram showing the configuration of a conventional optical disk substrate.

Explanation of symbols

1 Groove 2 Land 4 Optical spot for recording and reproduction 5 Disc substrate

Claims (9)

An optical disc having a recording track consisting of a groove and a land, and an address area starting at the same angular position as an adjacent recording track is formed on at least a part of the recording track, and either the groove or the land On the other hand, the first recording track has both side walls meandering according to the address information and substantially the same width in the address area, and among the portions meandering according to the address information, The meandering portion corresponding to each bit of the address information is synchronized between the first recording tracks adjacent to each other, and the synchronized meandering portions are formed to have the same length as viewed from the address reproducing system. An optical disk device for reproducing information from
When the light beam follows the first recording track, it has first address reproducing means for reproducing address information in the first recording track by detecting meandering of the side wall. Optical disk device. The optical disc apparatus according to claim 1,
The first address reproducing means detects the meandering of the side wall from the tracking signal,
Whether the light beam follows the first recording track or the second recording track sandwiched between two adjacent first recording tracks is selected by inverting the polarity of the tracking signal. An optical disc device characterized. 3. The optical disk apparatus according to claim 1 , wherein the first address reproducing means detects meandering of a side wall from a tracking signal, and the tracking signal is obtained by a push-pull method . A recording track comprising a groove and a land, and an address area starting at the same angular position as the adjacent recording track is formed on at least a part of the recording track, and the first one of the groove and the land One recording track is an optical disc apparatus for reproducing information from an optical disc in which both side walls meander according to address information and are formed to have substantially the same width in the address area,
When the light beam follows the first recording track, by detecting the meander of the side wall, the first address reproducing means for reproducing the address information in the first recording track, and the two light beams are adjacent to each other. Detecting means for detecting a different portion in which the shape of the side wall on both sides thereof is different when following the second recording track sandwiched between the first recording tracks;
An optical disc apparatus comprising: second address reproducing means for reproducing address information of the second recording track based on a detection result of the detecting means . A recording track comprising a groove and a land, and an address area starting at the same angular position as the adjacent recording track is formed on at least a part of the recording track, and the first one of the groove and the land One recording track has both side walls meandering in accordance with the address information in the address area and is formed to have substantially the same width. The address information recorded on the first recording track is transferred to the adjacent first recording track. An optical disk device for reproducing information from an optical disk composed of a Gray code that differs from recorded address information by only one bit,
When the light beam follows the first recording track, by detecting the meander of the side wall, the first address reproducing means for reproducing the address information in the first recording track, and the two light beams are adjacent to each other. Detecting means for detecting a different portion in which the shape of the side wall on both sides thereof is different when following the second recording track sandwiched between the first recording tracks;
An optical disc apparatus comprising: second address reproducing means for reproducing address information of the second recording track based on a detection result of the detecting means . 6. The optical disc apparatus according to claim 4, wherein the detecting means is configured to detect the optical beam from the optical disc when the light beam follows a second recording track sandwiched between two adjacent first recording tracks. An optical disc apparatus, wherein a difference portion in which the shape of the side wall on both sides of the second recording track is different is detected by detecting the change location of the total signal depending on the amount of reflected light. 7. The optical disk apparatus according to claim 4, wherein the second address reproducing means is adapted to meander the side wall at the matching portion other than the different portion when the light beam follows the second recording track. A matching part signal detecting means for obtaining a matching part signal based thereon, and adding at least two hypothetical signals by assuming that the signals in the different part are "0" and "1", and generating the at least two hypothetical signals; An optical disc apparatus comprising: combining means for selecting one of the at least two hypothetical signals based on a predetermined rule and using it as address information of the second recording track. 8. The optical disk apparatus according to claim 7, wherein a first error detecting means for determining a reading error when two of the at least two hypothetical signals are not address information of two first recording tracks adjacent to each other. An optical disc apparatus comprising: 9. The optical disc apparatus according to claim 4, wherein the second error is determined as a reading error when the number of the different portions existing in one second recording track does not match a predetermined value. An optical disc apparatus comprising a detecting means.

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