JP3987293B2 - Information playback method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides an information reproduction method,HighThe present invention relates to a reproducing method of a density information recording medium.
[0002]
[Prior art]
For example, Japanese Patent Laid-Open No. 6-176404 discloses a conventional example of a medium for performing high density (narrow track) recording. In this example, an optical recording medium having a groove portion and an inter-groove portion on a substrate and an information recording area in both the groove portion and the inter-groove portion is used as a recording medium, and a boundary portion between the groove portion and the inter-groove portion. A pre-pit is arranged as identification information of a recording unit (sector) on the virtual extension line. Thus, the recording information is recorded in both the groove portion and the inter-groove portion, and the identification (address) information indicating the recording area is assigned to the pre-pit, and a single pre-pit corresponds to the pair of groove portions and the inter-groove portion. Sharing address information. When this method is applied to, for example, a phase change recording medium or a magneto-optical recording medium, information on adjacent groove portions or groove portions is not mixed between the groove portions and the groove portions due to the interference effect in the light spot ( (There is no crosstalk), so that the track can be narrowed and high density recording is possible.
[0003]
[Problems to be solved by the invention]
However, in the above conventional example, information indicating the position on the medium is concentrated in the pre-pit portion, and since the pre-pit portions are discretely arranged, position information cannot be obtained in portions other than the pre-pit. For this reason, it is difficult to precisely and highly reliably control the speed of the disk, and there is a problem particularly in terms of reliability with respect to defects and the like.
[0004]
  BookinventionEyesIn general, solve the above problems and assign location information to parts other than pre-pitsTheAnother object of the present invention is to provide a high-density and high-reliability information recording / reproducing method by using an information recording medium.
[0005]
[Means for Solving the Problems]
  In the present invention, the following means are used in order to achieve the above object.
  As an information recording medium used in the method of the present invention,On the disk-shaped substrate, there is a substantially spiral or concentric track composed of both the groove portion and the groove portion sandwiched between the groove portions.ShiThe recording media are grouped into a plurality of radial regions, and in each group, each track is divided into arc-shaped recording units having the same central angle in the radial direction, and each recording unit is divided. Identification information indicating the recording unit is arranged, the groups are grouped so that the arc length is substantially constant, and the grooves and the grooves are swung (wobbled) in the radial direction.Information recording media.
[0006]
  As a result, the identification information is arranged for each recording unit, and the position information can be reliably obtained even in the recording unit by swinging the groove part and the inter-groove part which is the recording part, so that the recording information can be reliably accessed. Therefore, it is possible to position the recorded information accurately. In addition, since the recording units are arranged radially in the radial direction, access between tracks becomes easy, and crosstalk between position information of each recording unit is minimized.ThisThe Since the recording units are arranged so that the lengths of the arcs are substantially the same, the recording density becomes substantially uniform in the disc, and the entire surface of the disc can be used efficiently. In addition, it is possible to perform a precise correction of tracking deviation by using this swing.
[0007]
  grooveIn each group, the period and phase of the rocking of the part and the groove part are aligned radially with the adjacent track. As a result, the rocking between adjacent tracks can be reliably reproduced without interference, and the width of each track is constant, so that the recording characteristics are not affected.
  grooveA constant integer multiple of the period of rocking between the groove and the groove is made to coincide with the length of the arc-shaped recording unit. This makes it possible to reliably detect the start point and end point of the recording unit using the oscillation cycle and to detect the exact position in the recording unit. Further, since the length of the recording unit and the oscillation cycle are synchronized, the relative speed of the recording medium can be automatically kept constant by controlling the oscillation frequency to be constant.
[0009]
  KnowledgeAnother information is formed by prepits which are minute concave portions or convex portions arranged in a portion where the groove portion and the groove portion are interrupted. Thereby, it becomes easy to mass-produce the information recording medium in which the identification information is provided in advance by a simple manufacturing process such as injection molding, and thus the productivity of the information recording medium is improved.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
  《referenceExample 1 >> Information recording medium
  FIG.Used in the methodThe track and sector arrangement of the recording medium is shown. A plurality of groups 91, 92, 93 are arranged in the radial direction of the disk-shaped recording medium 8. The track 3 is wobbled by a minute amount in the radial direction. Each track is divided into a plurality of arc-shaped sectors (recording units) 1 aligned in the radial direction. The length of the arcuate sector 1 is substantially constant regardless of the group, and the number of sectors divided per round increases as the group has a larger radius.
[0036]
  Figure 1,An example of the arrangement of tracks in one group of information recording media is shown. Groove information tracks 3 having a width of 0.7 μm and a depth of 60 nm and inter-groove information tracks 4 having a width of 0.7 μm are alternately arranged. The groove part information track 3 and the groove part information track 4 are connected to each other by a switching part 5. That is, the groove portion 3 is configured to be connected to the adjacent groove portion 4 after one track and the groove portion 4 is connected to the adjacent groove portion 3 after one track. Each track is a sectionTIt is divided into a plurality of arc-shaped recording units 1, and identification information 2 is arranged at the head of each information recording unit 1. In this example, the sector length is about 8 mm, which corresponds to a user capacity of 2048 bytes. The groove and the groove are wobbled in the radial direction with an amplitude of about 20 nm.
The wobble period was set to 1/145 of the sector length, that is, about 55 μm. The ratio of 1: 145 was selected so that the wobble period was an integral multiple of the length of recording data (channel bit length). This makes it easy to generate a recording clock from the wobble.
[0037]
  2 and 3 are partial plan enlarged views of each information identification information portion. 2 shows that the tracks before and after the identification information are grooves.Mutual, Groove partMutualFIG. 3 shows a portion where the front and rear tracks are connected at the groove portion and the inter-groove portion, that is, the track where the identification information is adjacent in the direction along the information track.MutualAnd the two tracks are arranged so as to coincide with each other. In FIG. 2, the identification information is radially arranged at two locations of the first position 21 and the second position 22 along the radial direction. The front and rear tracks are grooves 3Mutual, Groove part 4MutualConnected with. In the example of this figure, each identification information corresponds to the recording area of the information track on the right side. Further, the identification information corresponding to the groove information track 3 on the right side of the drawing is arranged at the first position 21, and the identification information corresponding to the groove information track 4 is arranged at the second position 22.
That is, the identification information is a track whose position in the direction along the information track is adjacent.MutualAnd are arranged so as to coincide with two adjacent tracks.
[0038]
In the switching unit 5 of FIG. 3, the tracks before and after the identification information are connected to each other at the groove part and the groove part. Also in this case, each identification information corresponds to the recording area of the information track on the right side thereof, and the identification information corresponding to the groove information track 3 on the right side of the drawing is in the first position 21 and in the groove information track 4. Corresponding identification information is arranged at the second position 22.
[0039]
For this reason, for example, when the light spot 7 scans the inter-groove portion 4, only one of the pits is always reproduced, and there is no fear of crosstalk from adjacent tracks. Therefore, it becomes possible to reproduce the address information arranged in the prepits satisfactorily without crosstalk. In this example, prepit address information is recorded by an 8/16 modulation code (channel bit length 0.2 μm).
[0040]
  Figure 4,The configuration of the track and the identification information is shown in perspective, and it is shown that the identification information is formed by a small depression (pit) 23.thisIn the example, since the pits 23 are evenly arranged on both sides of the track (land portion or groove portion), the influence on the tracking servo signal generated by the pits 23 is canceled out. Therefore, the track offset can be kept sufficiently small. Further, for example, when the inter-groove portion 4 is reproduced, the address information of the first prepit portion 21 and the second prepit portion 22 is continuously reproduced. For this reason, if information is arranged so that both are combined into address information, an address (track number), that is, identification information can be set independently of the groove portion 4 and the groove portion 3. . That is, the land portion and the groove portion can be identified by continuously reproducing the address information of the first prepit portion 21 and the second prepit portion 22.
[0041]
  A specific example of identification information numbering is shown in FIG. The identification information of the recording area 11 and the recording area 12 is shown. In this example, information is recorded / reproduced while relatively scanning the detection spot from the left to the right. For example, the left groove track K is connected to the right groove track K + 1 of the switching portion 5. The left groove track K + 1 is continuous after one round of this track. In this example, for example, the identification information of the information recording area 81 of the groove track K is N-1 + S. Here, S represents the sum of optical recording information units per track. When the identification information portion 6 of this track is reproduced with a light spot or the like, N-1 + 2S is reproduced as identification information at the first position, and N-1 + S is reproduced as identification information at the second position. In this case, by determining that the smaller number is always adopted as the recording area number, N−1 is used as the identification information of the information recording area 81 of the groove track K.+S is adopted. Similarly, when scanning the inter-groove track K-1, N-1 is adopted as the identification information as the identification information at the first position. At the same time, it is possible to distinguish between the groove part and the groove part depending on whether the identification information at the first position or the identification information at the second position is adopted.
[0042]
When the information track in the track switching unit 5 is reproduced, the correspondence between the identification information and the recording information and the determination of the groove part and the groove part can be performed in the same manner. Therefore, by using this relationship, it is possible to switch the tracking polarity between the groove track and the groove track.
In this example, the first and second identification information portions are shown in the case of two sets. However, as long as there are a plurality of sets, for example, in the case of four sets, the first and third pre-pit portions are located below the groove portion. And the second and fourth prepit portions may be disposed above the groove portion. By increasing the number of pre-pit portions, the reliability with respect to defects and the like is improved.
Here, a phase change recording film (GeSbTe) was used as the recording film. Therefore, the recording mark is formed in the form of an amorphous region.
[0043]
  "Example1>> Information recording and playback method
  referenceAn example of a recording / reproducing method using the recording medium of Example 1 will be described with reference to FIG.referenceThe recording medium 8 of Example 1 is rotated by a motor 162. The light intensity control means 171 controls the light generation means 131 to generate light 122 so that the light intensity commanded by the central control means 151 is generated, and this light 122 is condensed by the light collection means 132 and the light spot 7 is reflected. It is formed on the information recording medium 8. Using the reflected light 123 from the light spot 7, the light detection means 133 detects it. This light detection means is composed of a light detector divided into a plurality of parts. The reproducing unit 191 reproduces information on the medium using the reproduction signal 130 from the photodetector. In order to detect the wobble of the track on the medium, a differential output between the outputs of the multi-division detector is used. This utilizes the fact that the intensity distribution of the diffracted light from the light spot changes depending on the positional relationship between the light spot and the track. Based on the wobble signal detected by the reproducing means, the information on the positional relationship between the spot and the track, and the prepit identification information, the position control means 161 controls the position of the light collecting means 132 and sets the rotation frequency of the motor 162. Control. The rotation frequency is controlled so that the frequency of the reproduced wobble signal becomes a predetermined constant value. By performing rotation control in this way, the motor can be automatically controlled at an appropriate rotation speed regardless of the group on the medium, and this rotation information is about 55 μm in one cycle. Therefore, the density of rotation information is very high, and high-precision rotation control is possible. Further, since this rotation information is arranged throughout the entire rotation of the disk, even if a part of it is lost due to dirt or a defect, it can be reproduced with no problem and with high reliability.
[0044]
  "Example2>> Information recording and playback method
  A method for recording and reproducing by generating a clock that synchronizes with the phase of the wobble signal at the time of recording / reproducing information will be described. A PLL (Phase-Locked Loop) circuit is used to generate this clock. Because this clock is accurately synchronized with the wobble information of the recording medium
By using this clock for recording / reproduction, recording / reproduction can be performed at a timing completely synchronized with the position on the medium, so that recording / reproduction can be performed without providing an unnecessary buffer area on the recording medium. A medium with high format efficiency can be used, and the recording capacity is improved. Further, since the wobble information (rotation information) is arranged throughout the entire rotation of the disk, even if a part is lost due to dirt or a defect, it can be reproduced with no problem and high reliability.
[0045]
  《Reference example 2>> Information recording medium
  In FIG.,The present inventionAn example of the method used inThe track and sector arrangement of the recording medium is shown.
A plurality of zones (groups) 91, 92, 93 are arranged in the radial direction of the disc-shaped recording medium 8 having a diameter of 120 mm. In this example, a radius of about 24 mm to 58 mm was divided into 24 zones. Therefore, the width of the band occupied by one zone is about 1.4 mm. The track 3 is wobbled by a minute amount in the radial direction. Each track is divided into a plurality of arc-shaped sectors (recording units) 1 aligned in the radial direction. The length of the arcuate sector 1 is substantially constant regardless of the zone (group), so that the number of divisions in one peripheral sector increases as the zone has a larger radius. ThisExampleIn this example, the recording is divided so that there are 17 recording units 1 per round in a zone around the radius of 25 mm (the innermost zone), and the number of divisions increases by one as the zone moves to the outer zone. . Thus, by using the recording media grouped so that the number of divisions on the outer circumference increases, the length of the recording unit 1 on the inner and outer circumferences can be made substantially constant. That is, the density can be made substantially constant, and the surface area of the medium can be used effectively. Further, since recording / reproduction control can be performed at the same rotation speed and recording frequency within each group, the configuration of the apparatus using the medium is simplified. Of course, the length of the recording unit is slightly different between the inside and outside of each zone.
[0046]
  Figure 1,An example of the arrangement of tracks in one group of information recording media is shown. The groove information track 3 having a width of 0.74 μm and a depth of 60 nm and the groove information track 4 having a width of 0.74 μm are alternately arranged. In each zone, about 950 groove tracks and the same number of groove tracks are disposed. The groove portion information track 3 and the groove portion information track 4 are connected to each other by a switching portion 5 provided at one place around the disk. That is, the groove portion 3 is configured to be connected to the adjacent groove portion 4 after one track and the groove portion 4 is connected to the adjacent groove portion 3 after one track. Each track is divided into a plurality of arc-shaped recording units 1, and identification information 2 is arranged at the head of each information recording unit 1. In this example, the length of the recording unit is about 8.5 mm, which corresponds to a user capacity of 2048 bytes.
[0047]
The groove and the groove are wobbled in the radial direction with a half-value amplitude of about 20 nm. The wobble period was set to 1/232 of the sector length, that is, about 37 μm. Here, the ratio of 1: 232 is set to this value not only in one group (zone) but also in all recording units on the disc. The ratio of 1: 232 was selected so that the wobble period was an integral multiple (186 times in this example) of the unit length (channel bit length) of the recording data. Therefore, the length of the recording unit is equivalent to 232 × 186 = 43152 channel bits in terms of the number of channel bits. As described above, since the wobble cycle is an integral multiple of the recording channel bits, the recording clock can be easily generated by multiplying the wobble frequency by an integral multiple. In addition, since the relationship between the information recording unit 1 and the swing length is the same over the entire surface of the disk, a recording clock can be generated by using the signal obtained from the swing without switching between zones. Therefore, it is possible to make the density in the disk substantially uniform with an apparatus having a simple configuration, and it becomes easy to efficiently use the entire surface of the disk. Furthermore, by performing rotation control so that the frequency of the wobble is constant, the relative linear velocity between the light spot and the medium can be controlled to be substantially constant regardless of the position of the recording medium. In this way, controlling the linear velocity substantially constant allows recording and reproduction under the same recording conditions regardless of the location of the medium, so that control of the recording and reproduction characteristics of the medium is simplified, and the recording apparatus and The medium can be easily configured. Here, since the length of the recording area 1 is slightly different between the inside and the outside of the zone, the length of a wobble having a period of an integer of a recording unit is also different on the inner and outer circumferences of the zone, and the linear velocity is slightly different accordingly. Needless to say. However, since the central angle formed by the recording unit is constant in the zone, the rotational speed (angular velocity) in the zone is constant, so that high-speed access in the zone is possible.
[0048]
  Further, here, since the integral multiple (232 times) of the wobble (swing) period is equal to the length of the recording unit 1, the phase of the swinging between the adjacent recording units 1 is the same. Since connection can be made without a half end, it is easy to generate a timing signal such as a clock across continuous recording units 1 by using oscillation. This connection without rocking is that the rocking phase is continuous between adjacent recording units 1, and the rocking is not always physically connected. There is no need to be. That is, it is possible to use a structure in which the oscillation is missing over several cycles at the boundary portion of the recording unit 1, and in this case, if the missing portion is compensated, the adjacent recording unit region 1 is used.MutualTherefore, it is only necessary that the rocking phases are continuously connected. In fact,thisIn the example, identification information 2 consisting of pre-pits is arranged at the beginning of the recording unit, and neither the groove part 3 nor the inter-groove part 4 exists, so that no wobble is formed. For this identification information 2, wobbles are missing for about 11.2 periods. Accordingly, the actual number of wobbles is about 220.8, but the length of the recording information unit is set to be exactly 232 times the wobble cycle.
[0049]
  hereWordsThe recording unit does not necessarily match the sector length. For example, the identification information may be arranged using two or more sectors as a recording unit. A plurality of recording units may be combined into a logical sector or a logical block for error correction. In any case,hereThe recording unit is an area having a substantially constant length in which identification information is arranged at the head.
[0050]
  2 and 3 are partial plan enlarged views of each information identification information portion. 2 shows that the tracks before and after the identification information are grooves.Mutual, Groove partMutualFIG. 3 shows a portion where the front and rear tracks are connected at the groove portion and the groove portion, that is, the track where the identification information is adjacent in the direction along the information track.MutualThese are different from each other and the two tracks are arranged so as to coincide with each other. In FIG. 2, the identification information is radially arranged at two locations of the first position 21 and the second position 22 along the radial direction. The front and rear tracks are grooves 3Mutual, Groove part 4MutualConnected with. In the example of this figure, each identification information corresponds to the recording area of the information track on the right side. Further, the identification information corresponding to the groove information track 3 on the right side of the drawing is arranged at the first position 21, and the identification information corresponding to the groove information track 4 is arranged at the second position 22. That is, the identification information is a track whose position in the direction along the information track is adjacent.MutualAnd are arranged so as to coincide with two adjacent tracks.
[0051]
  The wobble is formed so as to have a sine wave shape that starts with the same phase for all information tracks, and starts from immediately after the identification information section or starts through some buffer area. . By doing this, the point where the phase of the sinusoidal wobble is 0 degree is set to the adjacent track.MutualWhen tied together, they are arranged radially in the radial direction. For this reason, the track width does not change due to wobble. For this reason, there is no worry that the wobble adversely affects the recording / reproducing characteristics. If the wobble phase is not uniform in each track, a portion where the track width is modulated by the wobble is formed, which greatly affects the recording / reproducing characteristics. Therefore,next toIt is very important for the realization of the present invention that the wobble phases (including the polarities) be aligned between the adjacent tracks.
[0052]
In the switching unit 5 of FIG. 3, the tracks before and after the identification information are connected to each other at the groove part and the groove part. Also in this case, each identification information corresponds to the recording area of the information track on the right side, and the identification information corresponding to the groove information track 3 on the right side in the figure is located at the first position 21 and the groove information track 4. The identification information corresponding to is arranged at the second position 22.
[0053]
  For this reason, for example, when the light spot 7 scans the inter-groove portion 4, only one of the pits is always reproduced, and there is no fear of crosstalk from adjacent tracks.
Therefore, it becomes possible to reproduce the address information arranged in the prepits satisfactorily without crosstalk. In this example, prepit address information is recorded by an 8/16 modulation code (channel bit length 0.2 μm). Therefore, the shortest pit length is about 0.6 μm. From the point of simplification of the recording / reproducing apparatus, it is desirable that the modulation code of the pre-pit part and the modulation code of the user information recording part be the same,hereThe modulation code and the recording linear density are the same. For this reason, most of the circuits can be shared.
[0054]
  Figure 4 shows the bookReference exampleThe configuration of the track and the identification information is shown in perspective, and it is shown that the identification information is formed by small depressions (pits) 23. BookReference exampleSince the pits 23 are evenly arranged on both sides of the track (land portion or groove portion), the influence on the tracking servo signal generated by the pits 23 is canceled out. Therefore, the track offset can be kept sufficiently small. Further, for example, when the inter-groove portion 4 is reproduced, the address information of the first prepit portion 21 and the second prepit portion 22 is continuously reproduced. For this reason, if information is arranged so that both are combined into address information, an address (track number), that is, identification information can be set independently of the groove portion 4 and the groove portion 3. . That is, the land portion and the groove portion can be identified by continuously reproducing the address information of the first prepit portion 21 and the second prepit portion 22.
[0055]
  A specific example of identification information numbering is shown in FIG. The identification information of the recording area 11 and the recording area 12 is shown. In this example, information is recorded / reproduced while relatively scanning the detection spot from the left to the right. For example, the left groove track K is connected to the right groove track K + 1 of the switching portion 5. The left groove track K + 1 is continuous after one round of this track. In this example, for example, the identification information of the information recording area 81 of the groove track K is N-1 + S. Where S is track 1ZhouThe sum of the optical recording information units around is shown. When the identification information portion 6 of this track is reproduced with a light spot or the like, N-1 + 2S is reproduced as identification information at the first position, and N-1 + S is reproduced as identification information at the second position. In this case, by determining that the smaller number is always adopted as the recording area number, N−1 is used as the identification information of the information recording area 81 of the groove track K.+S is adopted. Similarly, when scanning the inter-groove track K-1, N-1 is adopted as the identification information as the identification information at the first position. At the same time, it is possible to distinguish between the groove part and the groove part depending on whether the identification information at the first position or the identification information at the second position is adopted.
[0056]
When the information track in the track switching unit 5 is reproduced, the correspondence between the identification information and the recording area and the determination of the groove part and the groove part can be performed in the same manner. Therefore, by using this relationship, it is possible to switch the tracking polarity between the groove track and the groove track.
In this example, the case where the identification information part is the first and second sets is shown. However, as long as there are a plurality of sets, for example, in the case of four sets, the first and second pre-pit parts are located below the groove part. The third and fourth pre-pit portions may be arranged on the upper side of the groove portion (outer in the radial direction). Alternatively, the first and third prepit portions may be disposed below the groove portion, and the second and fourth prepit portions may be disposed above the groove portion. By increasing the number of pre-pit portions, the reliability with respect to defects and the like is improved.
Here, a phase change recording film (GeSbTe) was used as the recording film. Therefore, the recording mark is formed in the form of an amorphous region.
[0057]
  "Example3>> Information recording and playback method
  Reference example 2An example of recording / reproducing with the apparatus of FIG.
Reference example 2The recording medium 8 is rotated by a motor 162. The light intensity control means 171 controls the light generation means 131 to generate light 122 so that the light intensity commanded by the central control means 151 is generated, and this light 122 is condensed by the light collection means 132 and the light spot 7 is reflected. It is formed on the information recording medium 8. Using the reflected light 123 from the light spot 7, the light detection means 133 detects it. This light detection means is composed of a light detector divided into a plurality of parts. The reproducing unit 191 reproduces information on the medium using the reproduction signal 130 from the photodetector. In order to detect the wobble of the track on the medium, a differential output between the outputs of the multi-division detector is used. This utilizes the fact that the intensity distribution of the diffracted light from the light spot changes depending on the positional relationship between the light spot and the track. Based on the wobble signal detected by the reproducing means, the information on the positional relationship between the spot and the track, and the prepit identification information, the position control means 161 controls the position of the light collecting means 132 and the rotational frequency of the motor 162. To control. The rotation frequency is controlled so that the frequency of the reproduced wobble signal becomes a predetermined constant value. By performing rotation control in this way, the motor can be automatically controlled at an appropriate rotation speed regardless of the zone on the medium, and this rotation information is about 37 μm in one cycle. Therefore, the density of rotation information is very high, and high-precision rotation control is possible. Further, since this rotation information is arranged throughout the entire rotation of the disk, even if a part of it is lost due to dirt or a defect, it can be reproduced with no problem and with high reliability.
[0058]
FIG. 8 shows an example of the reproduction signal 41 of the wobble information and the reproduction signal 42 of the identification information section. Here, consider the case where there are four sets of identification information sections. It is assumed that the first and second identification information 31 and 32 are on the lower side of the groove, and the third and fourth identification information 33 and 34 are on the upper side. In this example, a photodetector that is divided into at least two in the radial direction is used as a detector, and a differential signal between the two detectors is obtained. That is, a detection system similar to the push-pull signal detection system used for normal tracking control or the like was used. However, since the frequency of the wobble signal and the identification information signal is higher than the band for tracking servo, a high-frequency amplifier and differential circuit were prepared. Reproduction signals 421, 422, 423, and 424 were obtained corresponding to the first, second, third, and fourth identification information 31, 32, 33, and 34, respectively. When the light spot does not reach the pre-pit of the identification information section, the reflected light is uniformly incident on the above-described split detector, so that the reproduction signal (differential signal) output is almost zero, but the light spot is partially in the pre-pit. In the overlapped state (FIG. 2), the distribution of the reflected light from the light spot is greatly biased due to the diffraction effect, causing an imbalance in the output of the split detector, resulting in a large differential signal output. . At this time, since the direction of the bias differs depending on the positional relationship between the light spot and the pit, the polarity is inverted between the differential output corresponding to the identification information 31 and 32 and the differential output corresponding to the identification information 33 and 34. Therefore, even if the polarity is used, it is possible to identify whether the light spot is located in the groove portion or the inter-groove track. The identification information can be obtained by binarizing and decoding the signal obtained in this way by the tracking slice circuit. At this time, since the error detection information is added to the identification information, it can be determined whether or not the error detection information is correctly detected, and only the correct one of the plurality of identification information can be used.
[0059]
The wobble signal is detected in the same manner. That is, since the positional relationship between the light spot and the groove is modulated by wobble, a signal output 41 as shown in FIG. 8 is obtained. However, since the wobble amplitude (track displacement amount: 20 nm) is smaller than the displacement amount (about 0.3 μm) of the identification information, the amplitude of the wobble signal is correspondingly small.
[0060]
Next, FIG. 10 shows an example of a method for obtaining a timing signal (clock signal) from the wobble signal detected in this way.
First, the amplitude of the identification information section is limited by passing the reproduction signal of FIG. 8 through the limiter circuit of FIG. Next, only the signal of the component synchronized with the wobble signal is extracted using the band pass filter of FIG. Next, FIG. 10 (c) is binarized by a comparator, and finally FIG. 10 (d) uses a phase comparator, a filter circuit, a VCO (voltage controlled oscillator) and a phase-locked oscillator (PLL) having a period of 186 minutes. To obtain a clock signal. At this time, the characteristics of the filter used for the PLL are sufficiently higher than the frequency corresponding to the 11.2 wobble period in this example so as not to be affected by the missing part (identification information part) of the wobble signal. Set to lower. In this embodiment, since the wobble frequency is about 160 kHz, the frequency band of the PLL is set to about 2 kHz. It is desirable that this frequency be larger than the frequency (about 700 Hz) corresponding to the length of the recording unit from the viewpoint of speeding up at the time of access.
[0061]
  Thus, a clock signal synchronized with the wobble signal was obtained. A method for recording and reproducing information using this clock signal and identification information will be described below. FIG. 9 shows a timing chart for recording and reproduction. (A), (b), (c), and (d) are an identification information detection signal, a wobble signal, a clock signal, and a recording / reproducing timing signal. The identification information detection signal is a signal indicating that the identification information is normally detected. Normally, the recording unit area to be recorded / reproduced is identified based on this signal, and the recording and reproduction timing is controlled. BookExampleThen, as shown in FIG. 9, when the identification information could not be detected normally (in the figure, the x mark indicates that it could not be detected), the identification information detected normally last was used as a reference, By counting the clock signal obtained from the wobble signal, the recording / reproducing timing signal is obtained by substituting the identification information detection signal. In this way, even when the identification information cannot be detected normally, a recording / playback timing signal can be obtained. Since this signal is generated from a wobble signal synchronized with the recording medium, the rotation speed of the medium Even if there is an error such as, there is no possibility that the error is accumulated even if it is obtained accurately and a plurality of pieces of identification information cannot be detected continuously. For this reason, it is possible to construct a recording / reproducing apparatus that greatly allows errors in the identification information itself.
[0062]
In this way, by combining the signal detected from the wobble and the identification information, it becomes possible to identify the position of the light spot at all positions on the disc, thus improving the reliability of recording and reproduction. However, if this is used, for example, the reliability of recording and reproduction can be ensured without performing any inspection on the recording medium at the time of shipment of the medium, so that the cost of the recording medium can be greatly reduced. become. Moreover, since it becomes very strong against dirt, it is not necessary to protect it in a case or the like. For this reason, it becomes possible to provide a low-priced medium.
[0063]
According to the above embodiment, the reliability of recording / reproduction is greatly improved. For example, the reliability of recording / reproduction can be ensured without inspecting the recording medium when the medium is shipped. Can be greatly reduced. Moreover, since it becomes very strong against dirt, it is not necessary to protect it in a case or the like. For this reason, it becomes possible to provide a low-priced medium.
[0064]
Furthermore, since the recording units are aligned radially in the radial direction, access between tracks is facilitated, and crosstalk between position information of each recording unit is minimized.
Further, by arranging the recording units such that the arcs have substantially the same length, the recording density becomes substantially uniform in the disk, and the entire surface of the disk can be used efficiently.
[0065]
In addition, it is possible to reliably detect the start point and end point of the recording unit by using the oscillation cycle, and it is possible to accurately detect the position in the recording unit. Also, since the length of the recording unit and the oscillation cycle are completely synchronized, the rotation speed of the recording medium is automatically controlled by controlling the oscillation frequency constant, and the relative speed of the recording medium is substantially constant. It can control to become.
In addition, since it becomes easy to make the length of each recording unit on the recording medium constant, it is possible to minimize the length of the extra gap on the recording medium.
Furthermore, since the recording / reproducing can be performed while monitoring the track deviation amount, the reliability of the positioning servo is greatly improved.
[0066]
【The invention's effect】
In the present invention, the identification information is arranged for each recording unit, and the positional information can be reliably obtained even in the recording unit by the rocking of the groove part and the inter-groove part as the recording part, so that the recording information can be reliably accessed. At the same time, accurate recording information can be positioned.
[Brief description of the drawings]
FIG. 1 shows the present invention.Used in the methodInformation recording mediaOne caseThe top view which shows track arrangement | positioning.
FIG. 2Used in the methodInformation recording mediaOne caseThe top view which shows arrangement | positioning of identification information.
FIG. 3Used in the methodInformation recording mediaOne caseThe top view which shows arrangement | positioning of the identification information of the track connection part.
FIG. 4 The present inventionUsed in the methodThe partial expansion perspective view of an information recording medium.
FIG. 5 shows the present invention.Used in the methodInformation recording mediaOne caseThe top view which shows group division of.
FIG. 6Used in the methodInformation recording mediaOne caseThe top view which shows the example of numbering of identification information.
FIG. 7Used in the methodThe block diagram which shows an example of the recording / reproducing apparatus using an information recording medium.
[Fig. 8]The figure which shows the example of the reproduction signal of a wobble information, and the reproduction signal of an identification information part.
FIG. 9The figure which showed the timing chart of recording / reproducing.
FIG. 10The figure which shows an example of the method of obtaining a timing signal from a wobble signal.

Claims (1)

A method of reproducing information recorded on an information recording medium having a concentric or spiral groove structure along a track,
The information recording medium is grouped into a plurality of areas in the radial direction, and within each group, each track is divided into arc-shaped recording units having the same central angle radially aligned in the radial direction. the recording and prepits are disposed as identification information of a unit, and the length of the arc of the prior SL between front Symbol group are grouped so as to be approximately constant, the groove portions and the groove of the front Kimizo structure the inter has swung radially at a substantially constant period, the groove before Symbol before Symbol each recording unit is provided the portion broken in the circumferential direction, the prepits are arranged in the interrupted part, the length of the pre SL each recording unit is an integer multiple of the period before KiYurado, with respect to the information recording medium, the light generated from the light generating means is irradiated with light spots condensed by the condensing means,
Detecting the reflected light of the irradiated light, and controlling the position of the light collecting means based on the identification information and the wobble information detected based on the swinging ;
An information reproduction method for reproducing information recorded on the information recording medium.

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