JP4215405B2 - optical disk - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a recordable optical disc having a plurality of recording layers on one side.
[0002]
[Prior art]
  The recordable optical disc includes rewritable CD-RW, DVD-RW, DVD-RAM having a phase change material in the recording layer, and non-rewritable CD-R, DVD-R having an organic dye material in the recording layer. is there.
[0003]
  The optical disc apparatus records information by forming recording marks on the recording layer of the disc by changing the intensity of the light that is condensed and applied to the recording layer of these discs. A change occurs in the physical properties of the recording material at a location where the light intensity is high, a mark is formed, and a change occurs in the physical properties where the light intensity is low, resulting in a space.
[0004]
  In reproducing information, light having a smaller intensity than that at the time of recording is irradiated so that the physical properties of the recording layer do not change, and information is read by the difference in the amount of reflected light in the mark / space.
[0005]
  As a method for improving the recording capacity of these recordable discs, there is a single-sided dual-layer disc in which two recording layers are laminated on one side of the disc. This is based on the technique adopted in the DVD-ROM which is a read-only disk, and the irradiation light is the same as that of the disk produced by separating the two recording layers by a transparent layer. The selected recording layer is reproduced by being incident from the side.
[0006]
  In this method, it is necessary to use light transmitted through the recording layer on the front side when reproducing information on the recording layer located behind the light incident side. In a disc in which the recording layer in the foreground is recorded to the middle radial position, the following problems occur when trying to reproduce the recording layer on the back side.
[0007]
  8A, 8 </ b> B, and 8 </ b> C, the back recording layer 2 and the front recording layer 3 are laminated on a single-sided dual-layer disc 1, and the disc 1 is rotated by a spindle motor 4. The situation is shown in a cross-sectional view. The light 6 condensed by the objective lens 5 is focused on the back recording layer 2.
[0008]
  In the recording layers 2 and 3, the hatched part is the recorded area 7, and the hatched part is the unrecorded area 8. 8A and 8B show a disc in which recording is started from the inner recording layer 2 and then recorded from the outer peripheral side of the front recording layer 3 toward the inner peripheral side. .
[0009]
  FIG. 8A shows a state in which the recording layer 2 is recorded and reproduced through the unrecorded area 8 of the recording layer 3, and FIG. 8B shows the recording through the recorded area 7 of the recording layer 3. The state in which the layer 2 is recorded and reproduced is shown.
[0010]
  When reproducing near the inner periphery of the recording layer 2 through the unrecorded area 8 of the recording layer 3 on the front side as shown in FIG. 8A, and on the recording layer on the front side as shown in FIG. 8B. 3, a phenomenon occurs in which the amount of reflected light is different from the time of reproducing near the outer periphery of the recording layer 2 in the back through the recorded area 7.
[0011]
  In a two-layer disc, recording layers 2 and 3 are formed in a stacked manner, and tracks are formed separately in each layer. For this reason, the degree and position of the track eccentricity do not match between the recording layer 3 on the front side and the recording layer 2 on the back side.
[0012]
  As a result, when the recording layer 2 located in the vicinity of the boundary between the recorded area 7 and the unrecorded area 8 of the recording layer 3 on the front side is to be reproduced, the disc is deviated during one rotation of the disk due to the track eccentricity shift between the layers. 8A and 8B occur, and the amount of reflected light fluctuates in a short time.
[0013]
  The fluctuation in the amount of reflected light causes a reproduction error, and the reliability of the disk is lowered. Similarly, in the case of recording, when the states shown in FIGS. 8A and 8B occur, the light intensity reaching the inner recording layer 2 fluctuates, the recording marks become uneven, and writing cannot be performed stably.
[0014]
  On the other hand, in Japanese Patent Application Laid-Open No. 2000-285469, as shown in FIG. 8C, the recording layer 3 on the front side is recorded and then the recording layer 2 on the back side is recorded. ), A method for avoiding the state of (b) is disclosed.
[0015]
  If this method is used, when recording and reproducing the recording layer 2 in the back, the recording layer 3 in the foreground is already recorded on the entire surface. Unevenness of marks can be eliminated.
[0016]
  When recording / reproducing the front recording layer 3, there is no factor that changes the light intensity in the optical path (that is, the recording layer has the same conditions as recording / reproducing for a single-layer disc). Will not happen.
[0017]
[Problems to be solved by the invention]
  However, even when the method disclosed in Japanese Patent Laid-Open No. 2000-285469 described above is used, there is a problem in that the light intensity fluctuates when recording and reproducing the inner recording layer on the outermost and innermost circumferences of the disc. Still remains.
[0018]
  The reason for this will be described. FIG. 9 shows an example in which an optical pickup performs recording from the inner periphery to the outer periphery of the front recording layer and then jumps to the outermost periphery of the inner recording layer as disclosed in Japanese Patent Laid-Open No. 2000-285469. This shows the state near the outer periphery of the disc when recording is continued.
[0019]
  Due to the difference in track eccentricity between the recording layer 2 at the back and the recording layer 3 at the front, the states shown in FIGS. 9A, 9B, and 9C can be obtained. FIG. 9A shows the case where the radial positions of the outermost tracks of the recording layer 3 on the near side and the recording layer 2 on the back coincide with each other, and FIG. FIG. 9C shows the case where the radial position of the outermost track of the recording layer 3 is closer to the outer peripheral side than the radial position of the outermost track of the recording layer 2 in the back. The reverse case.
[0020]
  That is, the same problem as that described in the above prior art occurs when recording and reproducing the outermost circumference of the recording layer 2 at the back. In the case of a single-sided dual-layer DVD-ROM, the interlayer distance is about 50 μm, and the same interlayer distance is provided even in a recordable disc.
[0021]
  If NA of the objective lens 5 is 0.6, when the focus is on the recording layer 2 in the back, the recording layer 3 on the near side is irradiated with light in a region having a diameter of approximately 42 μm. Since the difference in track eccentricity between the layers is about 300 μm at the maximum, the states of FIGS. 9A, 9B, and 9C can occur.
[0022]
  Here, the outer peripheral side of the inner recording layer 2 is described as an example, but the situation is the same on the inner peripheral side of the inner recording layer 2, and the innermost periphery and outermost periphery of the inner recording layer 2 are the same. There is a problem that the recording and reproduction in the vicinity is not stable.
[0023]
  The present invention has been made in view of the above problems, and provides an optical disc that can stably perform recording and reproduction on a single-sided, dual-layer recordable disc.
[0024]
[Means for Solving the Problems]
  The first invention of the present application is capable of recording having a plurality of recording layers on one side.And record from the front layerIn an optical disc, each recording layer is formed with a groove or land, and a track capable of recording information is formed. When viewed from the light incident side, the data area of the front recording layer is the data area of the back recording layer. It is characterized by being wider.
[0025]
  Since the data area of the front recording layer is wider than the data area of the back recording layer, the outermost radial position of the recordable area in the front recording layer can be recorded in the back recording layer when viewed from the light incident side. The innermost radial position of the recordable area in the recording layer in the back is located on the outer peripheral side of the outermost radial position of the area, and the innermost radius of the recordable area in the inner recording layer It is characterized by being on the inner circumference side from the position.
[0026]
  Furthermore, in at least one of the recordable areas in the front recording layer and the back recording layer, at least one of the outer peripheral side and inner peripheral side areas adjacent to the user recording area where information is recorded by the user , By prelightInIt is characterized in that a configured area is provided.
[0027]
  In addition, in the above optical disc, a mark by pre-writeInThe recordable area provided with the configured area is at least the recordable area in the front recording layer as viewed from the light incident side.
[0028]
  Recordable with multiple recording layers on one sideAnd record from the front layerWith respect to the optical disc, in the recording / reproducing apparatus, when jumping between recording layers, the pickup can be jumped to a target recording layer after moving the pickup in a radial direction by a specified amount. According to this recording / reproducing apparatus, the jump destination between layers is always an area where a tracking signal can be obtained. Therefore, there is no damage to the actuator due to track deviation or delay of access to the target address. It becomes possible to improve the nature.
[0029]
  Recordable with multiple recording layers on one sideAnd record from the front layerWith respect to the optical disc, in the recording / reproducing apparatus, prior to the operation of recording information by the user, at least one of the recording layers, the outer peripheral side or inner peripheral side adjacent to the user recording area where the user can record information At least one of these areas can be prewritten. According to this recording / reproducing apparatus, as viewed from the light incident side, recording / reproduction at the outermost circumference and the innermost circumference of the inner recording layer is stable, and a highly reliable optical disc can be obtained.
[0030]
  When the pre-writing is performed, the recording layer in the back can be recorded before the recording layer in front as viewed from the light incident side. As a result, pre-writing can be performed stably, and a highly reliable optical disc can be manufactured.
[0031]
  The laser power for pre-writing and the laser power for recording user data in the user recording area of the inner recording layer can be different. As a result, pre-writing can be performed stably, and a highly reliable optical disc can be manufactured.
[0032]
  Recordable with multiple recording layers on one sideAnd record from the front layerWith respect to the optical disc, in the recording / reproducing apparatus, after the user finishes recording the information, at least one of the recording layers is on the outer peripheral side or the inner peripheral side adjacent to the user recording area where the information is recorded by the user. A recording area not including user data can be produced in at least one of the areas. According to this recording / reproducing apparatus, it is possible to reduce the burden on the buffer memory of the optical recording / reproducing apparatus, and to provide a highly reliable optical disc recording system.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the same parts as those in the conventional example are denoted by the same reference numerals, and the description thereof will be omitted.
[0034]
  FIG. 1A shows an optical disc according to an embodiment of the present invention. The recording layer is a phase change recording material used for DVD-RW and the like, and has a track in which a groove is formed in a spiral shape.
[0035]
  The front recording layer 3 as viewed from the light incident side has a wider writing area than the inner recording layer 2. That is, the outermost radial position of the recording area of the recording layer 3 on the front is outside the outermost radial position of the recording area of the inner recording layer 2, and the innermost radial position of the recording area is on the front. The layer is on the inside.
[0036]
  By setting the recording area in this way, as shown in FIG. 1 (b), when writing the back recording layer 2 after writing to the front recording layer 3, it is necessary to make sure that there is a recorded front in the incident optical path. The recording layer 3 enters. As a result, it is possible to prevent fluctuations in light intensity when recording and reproducing near the outermost periphery or the innermost periphery of the inner recording layer 2.
[0037]
  The radial positions of the recording areas of the front recording layer 3 and the back recording layer 2 satisfying such conditions are as follows.
[0038]
  As shown in FIG. 2, the NA of the objective lens 5 is α, and the refractive index of air is n.₁, The refractive index of the disk substrate is n₂, Θ₁, Θ₂When the distance between the front layer 3 and the back layer 2 is L, and when the focus is on the back layer 2, the radius of the front layer 3 in the optical path is P,
α = n₁sinθ₁
n₁sinθ₁= N₂sinθ₂
P = Ltanθ₂
It becomes.
[0039]
  From these equations,
P = Lα / (n₂ ²-Α²)^1/2
Is guided.
[0040]
  As shown in FIG. 1B, the radius position of the outermost periphery of the layer 3 on the near side is R_out, Radius position of innermost circumference is R_inAnd the radial position of the outermost periphery of the back layer 2 is r_out, R is the radius of the innermost circumference_ingiven that,
r_out+ P <R_out
R_in+ P <r_in
If this condition is satisfied, if there is no track eccentricity shift between layers, there will be no fluctuation in light intensity during recording / reproduction of the back layer 2.
[0041]
  When there is an eccentric deviation δ between layers,
r_out+ P + δ <R_out
R_in+ P + δ <r_in
As long as the relationship is satisfied.
[0042]
  In the present embodiment, a disk having the same parameters as a DVD having a diameter of 12 cm is made, so α = 0.6, L = 50 μm, n₂= 1.55 and P = 21 μm. Since the eccentric deviation of each layer track with respect to the disk substrate can be within 150 μm, the eccentric deviation δ between each layer track is 300 μm at the maximum, and P + δ = 321 μm.
[0043]
  Therefore,
R_out  Minimum value of 58.0mm
r_out  Maximum value of 57.67mm
R_inThe maximum value of 22.6mm
r_in  Minimum value of 22.93mm
As a result, it was possible to produce a disc that can stably perform recording and reproduction near the outermost periphery or the innermost periphery of the back layer 2.
[0044]
  Next, the state recorded on the dual-layer disc of this embodiment will be described in a little more detail. FIG. 3A shows the recording from the inner circumference to the outer circumference of the recording layer 3 on the near side, and then continues recording from the outer circumference to the inner circumference of the inner recording layer 2. Shows the disc that has been recorded.
[0045]
  N₀, N₃, N₄, N₇, N₈Are the first address of the recordable area of the front recording layer 3, the last address of the recordable area of the front recording layer 3, the first address of the recordable area of the back recording layer 2, and the back recording layer 2. , And the last address of the recordable area of the inner recording layer 2 are shown.
[0046]
  N₀, N₃, N₄, N₈Is determined so as to satisfy the above-described conditions. The area 8a is an unrecorded area and is an area that can be recorded by the user. On the other hand, the areas 8b-1, 8b-2, 8b-3, and 8b-4 are unrecorded areas, but are not recorded by the user.
[0047]
  The reason why the regions 8b-1, 8b-2, 8b-3, and 8b-4 are provided will be described. FIG. 4A shows an unrecorded track. A pit called a land pre-pit (LPP) is formed adjacent to a track composed of grooves (G). An address number is written in the LPP.
[0048]
  When the optical disk apparatus records information, tracking is performed by a push-pull method so that the light beam spot travels on the track. In the push-pull method, a tracking signal is obtained from the relative positional relationship between the light beam spot and the groove.
[0049]
  Also, the LPP signal appearing in the push-pull signal is read to detect the address number, and the recording is started from the target address or the recording is performed up to the target address. The traveling direction of the light beam spot is the direction of the arrow in the figure.
[0050]
  FIG. 4B shows that recording has started from the kth address. The shaded area is a recording area, and the area not shaded is an unrecorded area. By the way, in order to start recording accurately from the head of the kth address, the light beam spot travels on the track from the previous address area and detects the (k-1) th address. Need to be.
[0051]
  That is, a runway for starting recording is required before the k-th address at which recording starts. This is the (k−1), (k−2), (k−3), and (k−4) th address area in FIG.
[0052]
  FIG. 4C is a schematic diagram of a two-layer disc in which recording on the inner recording layer 2 is performed following recording on the front recording layer 3. In the front recording layer 3, recording is performed up to the i-th address in the direction of the arrow 131, and after the interlayer jump in the direction of the arrow 132, recording is performed in the direction of the arrow 133 from the j-th address of the back recording layer 2. Represents the state of starting.
[0053]
  As described with reference to FIG. 4B, in order to start recording from the jth address of the back recording layer 2, a runway is required, and the (j-1) th address of the back recording layer 2 is required. The previous area 135 corresponds to that. On the other hand, an area 134 where no recording is performed is provided after the i-th address at which recording on the previous recording layer 3 is completed.
[0054]
  If the area 134 is not provided, it is necessary to perform an interlayer jump or a movement jump to another track at the same time as the recording of the i-th address area is completed. It will disappear. Such a device is unstable and unreliable.
[0055]
  Therefore, by providing the region 134, the margin of the timing for performing the interlayer jump performed in the direction of the arrow 132 is widened, and the stability and reliability of the optical disc apparatus are improved. That is, an unrecorded area is always required before and after the recording area. The above is the reason why the regions 8b-1, 8b-2, 8b-3, and 8b-4 are provided in FIG.
[0056]
  Next, explanation will be given at the time of reproduction. When reproduction is performed, tracking is performed by a method called a differential phase detection method (DPD method). In the DPD method, a tracking signal is obtained from the positional relationship between a recording mark and a light beam spot. Therefore, a tracking signal cannot be obtained in a region where no pre-pit is used as used for a recording mark or a ROM disk.
[0057]
  Further, in the above-described LPP, a tracking signal by the DPD method does not come out. That is, as long as tracking is performed by the DPD method, a tracking signal cannot be obtained from a groove or LPP, and a tracking signal can be obtained only from a recording mark or a prepit used for a ROM disk.
[0058]
FIG. 5 shows a disc that has been recorded up to the i-th address of the front recording layer 3 and subsequently recorded from the j-th address of the back recording layer 2. When reproducing the information recorded on the disc, the information is read while tracking by the DPD method.
[0059]
  Information is reproduced using an RF signal, and the optical disc apparatus recognizes the reproduction start address and the reproduction end address by detecting the address number included in the read RF information.
[0060]
  The hatched area 144 and area 147 are areas where video, audio, etc. are recorded by the user. The area before the (i-2) -th address of the front recording layer 3 and the back recording layer 2 The area after the (j + 2) th address is used for this.
[0061]
  In areas 145 and 146 represented by dots, address information is included in the RF signal, but user data such as video and audio is not included. The (i-1) th and ith address areas 145 of the front recording layer 3 and the jth and (j + 1) th address areas 146 of the inner recording layer 2 are used for this.
[0062]
  The reason why the regions 145 and 146 are provided is the same as that in which the regions 134 and 135 are provided in FIG. That is, in order to accurately reproduce from the head of the address (j + 2), a runway that can be tracked by the DPD method is necessary before that, and the region 146 plays the role.
[0063]
  Further, after reproducing the information of the (i-2) th address, it is necessary to give a margin to the timing for performing an interlayer jump or moving to another track, and the region 145 plays the role.
[0064]
  When an area for giving a margin is added to the area for running in DPD tracking and the area for giving a margin to the jump timing after reproduction of the last address in which user information is recorded, the disc produced here is shown in detail in FIG. It has become.
[0065]
  Areas 7b-1, 7b-2, 7b-3, and 7b-4 are areas in which addresses by RF signals are recorded but user information such as video and audio is not included. In the area 7a, user information is recorded.
[0066]
  Next, the process of continuously recording and reproducing information will be described with reference to FIG. At the time of recording, the following operation process is performed.
[0067]
  (W1) Address N₀The pickup is moved to the inner peripheral side of the recording medium, and the laser power at the time of reproduction is used to focus on the recording layer 3 on the near side and track by the push-pull method.
[0068]
  (W2) Read LPP address, address N₀Will switch to recording power, and records with no user data will be stored in the address N.₁Do until.
[0069]
  (W3) Address N₁To address N₂Until then, user data is recorded.
[0070]
  (W4) Address N₂To address N₃Until then, record without user data.
[0071]
  (W5) Address N₃When recording is completed, the laser power is switched to the playback power, and the address N₃Remove the tracking on the outer circumference side.
[0072]
  (W6) An interlayer jump is performed, and the address N of the recording layer 2 in the back₄The focus is turned on to the outer periphery of the head and push-pull tracking is resumed.
[0073]
  (W7) Address N₄Will switch to recording power, and records with no user data will be stored in the address N.₅Do until.
[0074]
  (W8) Address N₅To address N₆Until then, user data is recorded.
[0075]
  (W9) Address N₆To address N₇Until then, record without user data. This completes the recording process.
[0076]
  Here, the “address N” shown in (W7) above.₄To address N₅The process of “recording without user data in the area up to” is the “address N” shown in (W9) above.₆To address N₇May be performed after the process of “recording without user data in the area up to”.
[0077]
  In that case, since the time until the recording of user data on the back recording layer 2 is resumed after the recording of user data on the front recording layer 3 is completed, the buffer memory described later is full. Problems can be avoided, continuous information input to the apparatus can be recorded on the disc without interruption, and highly reliable recording can be performed.
[0078]
  At the time of reproduction, the following operation process is performed.
[0079]
  (R1) Address N₀And N₁The pick-up is moved to a radial position between and the recording layer 3 on the near side is focused on with the reproduction power, and tracking is performed by the DPD method.
[0080]
  (R2) Read address from RF signal, address N₁Will start playing user data, address N₂Play until.
[0081]
  (R3) Address N₃By the time the address arrives, the address N₄And N₅The pickup is moved to a radial position between the two, an interlayer jump is performed, the focus is turned on to the recording layer 2 at the back, and DPD tracking is resumed.
[0082]
  (R4) Address N₅Will resume playing user data, address N₆Play until.
[0083]
  (R5) Address N₆Travel on the inner circumference of the car. This completes the serial reproduction process.
[0084]
  The control accompanying the interlayer jump in the reproduction process (R3) will be described in more detail with reference to FIG.
[0085]
  (R3-1) The area 144 of the recording layer 3 on the front side is reproduced in the direction of the arrow 140, and after entering the area 145, the tracking is removed.
[0086]
  (R3-2) With the focus on the recording layer 3 on the near side, the pickup is moved to the radial position of the region 146 in the direction indicated by the arrow 141.
[0087]
  (R3-3) An interlayer jump is performed in the direction indicated by the arrow 142 to focus on the area 146 and tracking of the recording layer 2 in the back is started.
[0088]
  (R3-4) Tracking is performed in the direction indicated by arrow 143, and reproduction is resumed from address (j + 2).
[0089]
  Here, since the radial positions of the regions 145 and 146 are known in advance, the movement amount of the pickup represented by the arrow 141 in (R3-2) is known in advance. Therefore, the pickup can be brought to the target radial position by controlling the pickup movement time and position sensor.
[0090]
  By the way, since the areas 7b-1, 7b-2, 7b-3, and 7b-4 record signals that do not contain user data, video and audio input to the apparatus while writing these areas. Information is temporarily stored in a semiconductor memory as a buffer.
[0091]
  If the recording of the area is completed before the buffer is full, user data that is continuously input can be recorded on the disk without interruption. However, if it takes a longer time than expected to write the area for some reason, the buffer may become full, and as a result, the continuity of user data that can be recorded on the disc may be lost.
[0092]
  Therefore, it is conceivable to pre-write areas 7b-1, 7b-2, 7b-3, and 7b-4 in advance before recording, thereby reducing the burden on the buffer. 6A shows a disk in which the areas 7b-1 and 7b-2 are prewritten, FIG. 6B shows a disk in which the area 7b-2 is prewritten, and FIG. 6C shows the areas 7b-1 and 7b- 2, 7b-3, 7b-4.
[0093]
  By using these, it is possible to shorten the time for recording other than the user data, so it is possible to record continuous data with high reliability.
[0094]
  As shown in FIG. 6C, in order to prewrite the areas 7b-1, 7b-2, 7b-3, and 7b-4, first, the area 7b-3, which is the area of the recording layer 2 at the back, It is necessary to record 7b-4 prior to the areas 7b-1 and 7b-2 which are areas of the recording layer 3 on the front side.
[0095]
  This is because if the areas 7b-1 and 7b-2 are recorded first, the problem of the light intensity variation described in FIG. 9 occurs when the areas 7b-3 and 7b-4 are recorded.
[0096]
  The above-described prewrite may be performed by a manufacturer at the time of shipment of the disk from the factory, or when the user inserts the disk into the optical disk apparatus, the optical disk apparatus may first perform a prewrite operation.
[0097]
  Prior to user data recording, in an optical disc apparatus that performs pre-writing as shown in FIG. 6C, it is necessary to select different laser powers for pre-writing and user data recording.
[0098]
  That is, in pre-write, the laser power (P1) for recording the back recording layer 2 in a state where the front recording layer 3 is not recorded, and the laser power (P2) used for recording the front recording layer 3 These two types of laser power must be selected depending on the recording layer.
[0099]
  On the other hand, in the recording of user data, the laser power (P3) for recording the back recording layer 2 in a state where the front recording layer 3 is recorded and the laser power (P2) used for recording the front recording layer 3 It is necessary to select according to the layer for recording two kinds of laser powers.
[0100]
  FIG. 7 (a) shows a pre-written disc in which the outermost and innermost radial positions of the user recording area are the same. FIG. 7B shows a state in which recording of the front recording layer 3 is finished and user data recording is started on the back recording layer 2.
[0101]
  At this time, all the previous recording layers 3 in the optical path are already recorded, and stable recording is possible. Moreover, the user data area of the inner recording layer 2 is not narrower than the user data area of the front recording layer 3 as shown in FIG. 3B, and the recording capacity can be increased.
[0102]
  In the embodiment of the present invention described above, a DVD parameter is used as the parameter of the disc. However, the value of the parameter is not limited to that described here, and various values can be taken. . Further, the material used for the recording layer is not limited to the phase change material, and an organic dye material used for DVD-R or the like can also be used.
[0103]
  Furthermore, as for the form of the track, the case where the recording is performed from the inner periphery to the outer periphery in the front recording layer and the recording is performed from the outer periphery to the inner periphery in the inner recording layer has been described. It is not limited to what has been described here, but can take various forms.
[0104]
  Although the prewritten disc has been described, the same effect can be obtained by using prepits such as those used in a ROM disc instead of prewriting. In this case, since it is not necessary to prewrite, it is possible to reduce the cost of the disk and the time until the start of user data recording.
[0105]
【The invention's effect】
  According to the present invention, when viewed from the light incident side, recording / reproduction in the vicinity of the outermost circumference and innermost circumference of the inner recording layer is stable, and an optical disk with high reliability can be obtained.
[0106]
  Further, in at least one recording layer of the front recording layer and the back recording layer, a mark by pre-writing is provided on at least one of the outer peripheral side or inner peripheral side adjacent to the user recording area where information is recorded by the user.InSince the configured area is provided, not only can the recording / reproduction be performed in the vicinity of the outermost periphery / innermost periphery of the recording layer at the back as seen from the light incident side, but a highly reliable optical disc can be obtained. Therefore, it is possible to reduce the burden on the buffer memory of the optical recording / reproducing apparatus and to provide a highly reliable optical disc.
[0107]
  In addition, a pre-light markerInWhen the recordable area in which the structured area is provided is the recordable area in the recording layer at least on the near side when viewed from the light incident side, the outermost circumference and the outermost of the inner recording layer are viewed from the light incident side. Not only recording / reproducing in the vicinity of the inner periphery is stabilized, but also the user data area of the inner recording layer can be expanded, so that the storage capacity of the disk can be increased.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of an optical disc according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a state in which light is incident on a two-layer disc.
FIG. 3 is an explanatory diagram showing a detailed configuration of an optical disc according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a recording process.
FIG. 5 is a diagram illustrating a playback process.
FIG. 6 is an explanatory diagram showing an example of a prewritten optical disc according to the embodiment of the present invention.
FIG. 7 is an explanatory diagram showing another example of a prewritten optical disc according to an embodiment of the present invention.
FIG. 8 is an explanatory view showing a conventional optical disc.
FIG. 9 is a diagram for explaining a problem of a conventional optical disc.
[Explanation of symbols]
1 Double-layer disc
2 Back recording layer
3 Front recording layer
4 Spindle motor
5 Objective lens
6 Light beam
7 Recorded area
7a Recorded area
7b-1, 7b-2, 7b-3, 7b-4 Recorded area
8 Unrecorded area
8a Unrecorded area
8b-1, 8b-2, 8b-3, 8b-4 unrecorded area
134, 135 Unrecorded area
140, 141, 142, 143 Directional arrows
144, 147 Recorded user data
145, 146 Recorded non-user data

Claims (2)

In an optical disc having a plurality of recording layers on one side and capable of recording from the front layer , each recording layer is formed of a groove or land, and a track on which information can be recorded is formed. When viewed from the side, the outermost radial position of the recordable area in the front recording layer is on the outer peripheral side of the outermost radial position of the recordable area in the inner recording layer, and the recording in the previous recording layer The innermost radial position of the recordable area is on the inner peripheral side of the innermost radial position of the recordable area in the inner recording layer, so that the recordable area of the front recording layer is the innermost recording layer. A user whose information is recorded by the user in a recording layer that is wider than the recordable area of the recording layer and in at least one of the recordable areas in the front recording layer and the back recording layer On at least the outer peripheral side or the inner circumferential side area adjacent to the recording area, an optical disc, wherein a region composed of a mark is provided by prewriting. The optical disc according to claim 1,
The recordable area in which the area composed of marks by pre-write is provided, as viewed from the light incident side, the optical disk, characterized in that said recordable area at least the front-side recording layer.

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