JP2009181614A - Optical disk and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical disk device quickly and smoothly entering a reproducing operation, and to provide an optical disk. <P>SOLUTION: The number of layers of recording layers arranged in a disk is discriminated (S102). When the three or more layers are discriminated in the recording layers (S104:YES), a central recording layer (Lc) arranged in the lamination direction is decided as an initial recording layer (Lp)(S105, S106), the focal position of a laser beam is pulled in the initial recording layer by controlling an optical pickup device in a standby state before reproduction (S202). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc and an optical disc apparatus, and is particularly suitable for use in an optical disc in which three or more recording layers are arranged in the stacking direction and an optical disc apparatus that performs recording / reproduction on this optical disc.

  In recent years, with the increase in capacity of optical discs, the number of recording layers has been increasing. By including a plurality of recording layers in one disc, the data capacity of the disc can be remarkably increased. In the case of laminating recording layers, two single-sided layers have been common so far, but recently, in order to further increase the capacity, it is also considered to arrange three or more recording layers on one side. . Here, when the number of recording layers is increased, the capacity of the disk can be increased. On the other hand, the interval between recording layers is narrowed, and signal degradation due to interlayer crosstalk increases. However, if unnecessary light (stray light) from other than the target recording layer can be appropriately suppressed / removed, a smooth reproduction operation can be realized even when the number of stacked layers is three or more.

The following Patent Document 1 describes a technique for removing stray light using a pinhole. Patent Document 2 below describes a technique for preventing the influence of interlayer loss talk in a single-sided two-layer information recording medium.
JP 2006-260669 A JP 2007-080367 A

  When playing back a disc having a plurality of recording layers, usually, focus pull-in (focus search) is performed on the target recording layer, and then focus servo and tracking servo are applied to start playback. However, when the number of recording layers is increased, it takes time to focus on the target recording layer, and there is a problem that it is not possible to quickly shift to the reproducing operation. Normally, focus pull-in is performed by sequentially scanning the focus position of the laser beam from the outside of the disk surface to the target recording layer. However, in this case, if the deepest recording layer when viewed from the disk surface is the target recording layer, the focus position of the laser beam needs to be greatly scanned during focus pull-in, which requires a long time for focus pull-in. End up.

  In addition, when a large number of recording layers are arranged in the disc as described above, the distance from the disc surface to each recording layer differs for each recording layer. For this reason, it is necessary to provide aberration correction means such as a beam expander in the optical pickup device to correct the aberration for each recording layer. However, in this case, if the target recording layer is at the innermost position as described above, the expander is moved from the initial position (position adapted to the recording layer closest to the disk surface) to the innermost recording layer at the time of aberration correction. Therefore, it takes a long time for the drive control of the expander. Therefore, also from this point, rapid regeneration transition is hindered.

  On the other hand, when the drive speed of the expander is increased in order to avoid this problem, the power consumption increases accordingly, and the amount of heat generation also increases. If the calorific value increases in this way, the optical system may be adversely affected.Furthermore, when dust or the like is generated due to friction from the expander drive unit due to high-speed driving, the dust may interfere with the drive of the expander. There is also a risk of it occurring.

  An object of the present invention is to solve such a problem, and an object thereof is to provide an optical disc apparatus and an optical disc capable of quickly and smoothly shifting to a reproduction operation.

  An optical disc device according to a first aspect of the present invention includes an optical pickup device that irradiates a disc with laser light, a layer number discriminating unit that discriminates the number of recording layers arranged in the disc, and the layer number discriminating unit. A recording layer determining unit that determines a central recording layer as an initial recording layer among the recording layers arranged in the stacking direction when the number of recording layers determined by the recording unit is three or more, and in a standby state before transition to reproduction And a reproduction preceding processing unit that controls the optical pickup device and draws the focal position of the laser light into the initial recording layer.

  According to the optical disk device of this aspect, in the standby state before the transition to reproduction, the focal position of the laser beam is drawn into the central recording layer among the three or more recording layers arranged in the stacking direction. The amount of movement of the laser beam focal position can be suppressed to about half of the distance between the recording layer closest to the laser beam incident surface side and the innermost recording layer farthest from the incident surface. . For this reason, regardless of which recording layer is the target recording layer to be reproduced, the focal position of the laser beam can be quickly drawn into the target recording layer, and the time required to start reproduction can be shortened.

  Further, when the aberration correction means is configured by an expander as described above, the drive amount of the expander at the time of reproduction transition can be reduced to about half of the maximum stroke. Can be quickly adjusted to a state corresponding to the target recording layer. Therefore, also from this point, according to the optical disc apparatus according to this aspect, it is possible to speed up the reproduction transition.

  In the first aspect of the present invention, the “standby state” refers to a state in which a movie information menu screen is displayed, for example, a state in which a subsequent operation shifts to a reproduction operation, that is, a reproduction operation. It means the state of the previous stage. Here, up to which stage before the transition to the reproduction operation is set to the “standby state” is a matter that can be appropriately determined for each apparatus.

  In the optical disc apparatus according to the first aspect, when the number of recording layers arranged in the disc is three or more and an even number, the recording layer determining unit is one of the two central recording layers. Is determined as the initial recording layer. In this case, for example, the recording layer determination unit may be configured to determine, as the initial recording layer, a recording layer on the back side as viewed from the laser light incident surface side, out of the two central recording layers.

  The optical disc according to the second aspect of the present invention includes three or more recording layers in the stacking direction, and management information for managing information recorded on the disc is recorded on at least the central recording layer among these recording layers. It is characterized by.

  In the optical disc according to this aspect, since the central recording layer in which the management information is recorded is read in the initial operation after the disc is mounted, the focal position of the laser beam can be easily set on the central recording layer after the initial operation. Can be positioned. Therefore, when the optical disc according to this aspect is played back by the optical disc apparatus according to the first aspect, the focal position of the laser beam is recorded at the center in the standby state from the initial operation after the disc is loaded to the playback operation. It can be positioned smoothly in the layer.

  When the optical disc according to the second aspect of the present invention includes three or more and even number of recording layers in the stacking direction, the management information can be recorded on at least one of the two central recording layers. In this case, for example, the management information can be recorded in the recording layer on the back side when viewed from the laser light incident surface side, of the two central recording layers.

  An optical disc device according to a third aspect of the present invention includes an optical pickup device that irradiates a disc with laser light, a recording control unit that controls the optical pickup device to record information on the disc, and an optical disc device disposed in the disc. A layer number discriminating unit for discriminating the number of recorded layers, wherein the recording control unit is arranged in the stacking direction when the number of recording layers discriminated by the layer number discriminating unit is three or more. Management information for managing information recorded on the disc is recorded in a central recording layer of the recording layers.

  In the optical disc device according to this aspect, when the number of recording layers is three or more, management information is recorded in the central recording layer. Therefore, when a disc recorded by the optical disc apparatus according to this aspect is loaded into a player, the central recording layer in which the management information is recorded is read out in the initial operation. The focal position of the laser beam can be easily positioned on the central recording layer. Therefore, when the disc recorded by the optical disc apparatus according to this aspect is reproduced by the optical disc apparatus according to the first aspect, the laser beam is in a standby state from the initial operation after the disc is mounted to the reproduction operation. Can be smoothly positioned on the central recording layer.

  In the optical disc apparatus according to the third aspect, when the number of recording layers arranged in the disc is three or more and an even number, the recording control unit is configured to output at least one of the two central recording layers. The management information is recorded in In this case, for example, the management information can be recorded in the recording layer on the back side when viewed from the incident surface side of the laser beam, of the two recording layers in the center.

  As described above, according to the present invention, it is possible to provide an optical disc apparatus and an optical disc that can quickly and smoothly shift to a reproducing operation.

The features and significance of the present invention will become more apparent from the following description of embodiments. However, the following embodiment is merely an example for carrying out the present invention, and the present invention is not limited by the following embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, the present invention is applied to an optical disc having three or more recording layers corresponding to a blue wavelength band laser beam and a recording / reproducing apparatus thereof.

  FIG. 1 shows the structure of a disk 10 having three recording layers. As shown in the figure, the disk 10 has a structure in which three recording layers 12, two intermediate layers 13, a substrate 14, and a printing layer 15 are sequentially laminated on a substrate 11.

  The substrates 11 and 14 are formed of a material that easily transmits laser light having a wavelength of about 400 nm, such as polycarbonate. In addition, as a material for forming the substrates 11 and 14, a biodegradable material mainly composed of polyolefin, polylactic acid, or the like can be used. On the substrates 11 and 14, tracks made of pit rows, grooves, and the like are formed in a spiral shape. These substrates 11 and 14 are formed by injection molding.

  When the disk 10 is a ROM (Read Only Memory) medium, of the three recording layers 12, the first (layer 0) and second (layer 1) recording layers from the laser light incident side are half. The innermost recording layer 12 (layer 2) is formed of a transmissive material, and is formed of a high reflectance material. When the disk 10 is an R (Recordable) medium, the first (layer 0) and second (layer 1) recording layers are formed by laminating a recording film and a semi-transmissive film. In the third recording layer (layer 2), the recording film and the reflective film are laminated.

  Of the three recording layers 12, the first (layer 0) and third (layer 2) recording layers 12 are formed by sputtering or the like on the surfaces of the substrates 11 and 14 on which the tracks are formed, respectively. Then, an ultraviolet curable resin is applied on the recording layer 12 of the first layer (layer 0), a stamper having a track on the surface is pressed thereon, and ultraviolet rays are irradiated in this state to cure the ultraviolet curable resin. . Thereafter, the stamper is peeled off to form the first intermediate layer 13 to which the tracks on the stamper are transferred.

  An ultraviolet curable resin is further applied onto the intermediate layer 13, and a substrate 14 on which the recording layer 12 is formed is overlaid from the recording layer 12 side. Thereafter, the ultraviolet curable resin is cured by irradiating with ultraviolet rays. As a result, a second intermediate layer 13 is formed, and the substrate 11 and the substrate 14 are bonded together with the intermediate layer 13 as a medium. Here, the two intermediate layers 13 are formed of an ultraviolet curable resin having a low absorption rate for light having a wavelength of about 400 nm.

  In the configuration of FIG. 1, the distance between the recording layers 12 of the first layer (layer 0) and the second layer (layer 1), and the recording layers 12 of the second layer (layer 1) and the third layer (layer 2). Both distances are d1. Here, the distance d1 is set to about 15 to 40 μm, for example, in order to suppress interlayer crosstalk.

  FIG. 2 is a diagram illustrating a configuration (optical system) of the optical pickup device. 2A is a plan view of the optical system excluding the quarter-wave plate 107 and the objective lens 108. FIG. 2B is a plan view of the rising mirror 106, the quarter-wave plate 107 and the objective lens 108. FIG. It is a side view of the optical system in a part.

  The semiconductor laser 101 emits laser light having a wavelength of about 400 nm. The diffraction grating 102 divides the laser beam emitted from the semiconductor laser 101 into a main beam and two sub beams. The collimating lens 103 converts the laser light incident through the diffraction grating 102 into parallel light. The polarization beam splitter 104 transmits the laser light incident from the collimating lens 102 side substantially completely and reflects the laser light incident from the expander 105 side substantially totally.

  The expander 105 is a combination of a concave lens and a convex lens, and one of these lenses is driven in the optical axis direction by the aberration actuator 133. Here, the aberration actuator 133 includes a motor, a worm gear, and the like, and is driven according to a servo signal for correcting the aberration of the laser light on the recording layer 12.

  The raising mirror 106 reflects the laser beam incident from the expander 105 side toward the objective lens 108. The quarter wavelength plate 107 converts the laser light incident from the rising mirror 106 side into circularly polarized light, and converts the laser light incident from the objective lens 108 side (reflected light from the disk 10) into the rising mirror. The laser beam is converted into linearly polarized light that is orthogonal to the polarization direction of the laser light when incident from the side 106. The objective lens 108 converges the laser light on the recording layer 12. Here, the NA of the objective lens 108 is 0.65.

  The quarter-wave plate 107 and the objective lens 108 are mounted on a common holder 131. Here, the holder 131 is driven in the focus direction and the tracking direction by the objective lens actuator 132. The objective lens actuator 132 includes a conventionally known coil and a magnetic circuit, and the coil is mounted on the holder 131. By supplying a servo signal to the objective lens actuator 132, the quarter-wave plate 107 and the objective lens 108 are displaced integrally with the holder 131 in the focus direction and the tracking direction.

  The anamorphic lens 109 introduces astigmatism into the laser light (reflected light from the disk 10) reflected by the polarization beam splitter 104. The photodetector 110 receives the laser beam converged by the anamorphic lens 109 and outputs a detection signal. The photodetector 110 is provided with a quadrant sensor that receives the main beam and a sensor that receives each of the two sub beams. The photodetector 110 is arranged so that the optical axis of the main beam passes through the intersection position of the sensor dividing line of the four-divided sensor, and the two sub beams are appropriately irradiated to the corresponding sensors.

  FIG. 3 shows the configuration of an optical disk apparatus that records and reproduces data on the disk 10. This optical disk apparatus can be applied to a disk having two or less recording layers or four or more recording layers in addition to the disk 10 shown in FIG.

  As shown, the optical disc apparatus includes an encoder 201, a modulation circuit 202, a laser drive circuit 203, an optical pickup device 204, a signal amplification circuit 205, a demodulation circuit 206, a decoder 207, a servo circuit 208, a controller. 209.

  The encoder 201 performs encoding processing such as addition of an error correction code on the input recording data, and outputs it to the modulation circuit 202. The modulation circuit 202 performs predetermined modulation on the input recording data, generates a recording signal, and outputs the recording signal to the laser driving circuit 203.

  The laser drive circuit 203 supplies a drive signal corresponding to the recording signal from the modulation circuit 202 to the semiconductor laser 101 in the optical pickup device 204 during recording, and emits laser light with a constant power during reproduction. A drive signal is supplied to the semiconductor laser 101 in the pickup device 204. Here, the laser power during recording and reproduction is controlled by the controller 209. At the time of recording, the controller 209 performs test writing in the test writing area and sets the laser beam to the optimum power.

  The optical pickup device 204 includes the optical system shown in FIG. The signal amplifying circuit 205 amplifies and calculates the detection signal in the photodetector 110 in the optical pickup device 204 to generate a reproduction RF signal, a focus error signal, a tracking error signal, and the like, and converts these signals into corresponding circuits. Supply.

  In this embodiment, the astigmatism method is used as a focus error signal generation method, and the three-beam method is used as a tracking error signal generation method. The photodetector 110 in the optical pickup device 204 has sensor patterns corresponding to these methods, and the signal amplification circuit 205 also performs arithmetic processing on signals from these sensor patterns so as to adapt to these methods. A focus error signal and a tracking error signal are generated.

  The demodulation circuit 206 demodulates the reproduction RF signal input from the signal amplification circuit 205 to generate reproduction data, and outputs this to the decoder 207. The decoder 207 performs decoding processing such as error correction on the data input from the demodulation circuit 206 and outputs the decoded data to a subsequent circuit.

  The servo circuit 208 generates a focus servo signal and a tracking servo signal from the focus error signal and tracking error signal input from the signal amplification circuit 205 and outputs them to the objective lens actuator 132 in the optical pickup device 204. In addition, the servo circuit 209 drives the aberration actuator 133 in the optical pickup device 204 as described later during the recording / reproducing operation.

  The controller 209 includes a CPU (Central Processing Unit) and a memory, stores various data in the memory, and controls each unit according to a control program stored in the memory in advance.

  The controller 209 determines the number of recording layers arranged in the disc according to the control program, and determines which recording layer from among the recording layers arranged in the disc as the initial recording layer. “Recording layer determination process” for determining whether to set (L0), and “reproduction preceding process” for drawing the focal position of the laser light emitted from the optical pickup device 204 into the initial recording layer (L0) in the standby state before the transition to reproduction. "And execute.

  FIG. 4 is a flowchart showing the operation of the optical disc apparatus when the disc is loaded. Among the processes in this flowchart, S102 is “recording layer determination processing”, and S104, S105, S106, and S107 are “recording layer determination processing”.

  When the disc is loaded (S101: YES), the controller 209 detects how many recording layers are arranged in the loaded disc (S102). For this detection, for example, the focus position of the laser beam emitted from the optical pickup device 204 is scanned from the outside of the laser beam incident surface of the disc to the inside of the disc, and an S-character appears on the focus error signal at that time. This is done by counting the number of curves.

  When the number of recording layers is detected, the controller 209 causes the optical pickup device 204 to access the management information recording position of the disc, reads the management information from the disc, and stores the read management information in the memory. (S103). Here, the management information is information for managing main information recorded on the disc. For example, the start information of each file recorded on the disc and a recording sector are linked to form a series of information. Link information and the like.

  At the time of reading the management information, the servo circuit 208 receives a command from the controller 209, executes a focus search, and records the focus position of the laser beam emitted from the optical pickup device 204 to hold the management information. Pull into the layer. Further, the servo circuit 208 supplies a focus servo signal and a tracking servo signal to the objective lens actuator 132 in the optical pickup device 204, and executes focus servo and tracking servo for the objective lens. Further, the servo circuit 208 monitors the reproduction RF signal at the time of management information reading, and controls the aberration actuator 133 so that the reproduction RF signal becomes the best.

  When the management information is read, the controller 209 determines whether the number of recording layers detected in S102 is 3 or more (S104). If the number of recording layers is three or more (S104: YES), the central recording layer (Lc) among these recording layers arranged in the stacking direction is discriminated (S105), and this recording layer (Lc ) Is set in the initial recording layer (Lp) (S106). On the other hand, if the number of recording layers of the disc is two or less (S104: NO), the first recording layer (layer 0) from the laser light incident surface side is set as the initial recording layer (Lp) (S107). . The “initial recording layer” refers to a recording layer in which the focal position of the laser beam is drawn in the standby state before the transition to reproduction, among the recording layers present in the disc.

  Note that in S105, if the number of recording layers detected in S102 is n, the recording layer of the order obtained by the following equation is determined as the central recording layer (Lc) from the laser light incident side.

Lc = 1 + INT (n / 2) (1)
Here, INT (k) is a function for obtaining the maximum integer among integers not exceeding k.

  Therefore, when the number of recording layers of the loaded disc is 3 or more and an even number, the controller 209 determines that the recording layer on the back side as viewed from the laser light incident surface side of the two central recording layers. Is the central recording layer (Lc). For example, when the number of recording layers is four, the controller 209 determines that the third recording layer (layer 2) from the laser light incident surface side is the central recording layer (Lc).

  FIG. 5 is a flowchart showing the operation of the optical disc apparatus during disc playback. Among the processes in this flowchart, S201 to S204 and S207 are “reproduction preceding processes”.

  In this processing flow, first, it is determined whether or not the optical disc apparatus has been set to a standby state before transition to reproduction (S201). Here, the “standby state” refers to a state in which a subsequent operation shifts to a reproduction operation, for example, a state in which a movie information menu screen is displayed, that is, a state in a previous stage of the reproduction operation. . Here, up to which stage before the transition to the reproduction operation is set to the “standby state” can be appropriately determined for each apparatus. Note that when the flow shown in FIG. 4 is executed after the disc is loaded, there is a high possibility of shifting to the reproduction operation thereafter. Therefore, normally, the state in which the flow shown in FIG. 4 is completed is a “standby state”.

  When the optical disk device is set to the standby state before the transition to reproduction (S201: YES), the controller 209 controls the servo circuit 208 to determine the focal position of the laser light emitted from the optical pickup device 204 in FIG. It is drawn into the initial recording layer (Lp) set in S106 or S107 (S202). In response to this, the servo circuit 208 performs a focus search, and draws the focal position of the laser light emitted from the optical pickup device 204 into the initial recording layer (Lp).

  For example, if the disc to be reproduced is the disc 10 shown in FIG. 1, since the second recording layer (layer 1) from the laser light incident surface is set as the initial recording layer (Lp), the focus of the laser light The position is drawn from the laser light incident surface to the second recording layer (layer 1). Further, if the reproduction target disc has two recording layers, the first recording layer (layer 0) from the laser light incident surface is set as the initial recording layer (Lp). The position is drawn from the laser light incident surface to the first recording layer (layer 0).

  Thus, when the focal position of the laser beam is drawn into the initial recording layer (Lp), the controller 209 causes the servo circuit 208 to execute focus servo, tracking servo, and aberration servo for a predetermined track. In response to this, the servo circuit 208 supplies a focus servo signal and a tracking servo signal to the objective lens actuator 132 in the optical pickup device 204, and executes focus servo and tracking servo for the objective lens. Further, the servo circuit 208 monitors the reproduction RF signal when the track designated by the controller 209 is read, and controls the aberration actuator 133 so that the reproduction RF signal becomes the best. After that, the servo circuit 208 keeps these servos ON, and repeats one track jump for each disk rotation, and controls the optical pickup device 204 so that the focal position of the laser beam repeatedly operates on the designated track. To do.

  In parallel with this, the controller 209 activates a built-in timer (S203), and then determines whether a reproduction operation (reproduction operation of a predetermined file) is started (S204). If the reproduction operation is not started before the measured time T of the timer exceeds the predetermined threshold time Ts (S204: NO, S207: YES), the controller 209 cancels the pull-in to the initial recording layer (Lp). Then, the optical pickup device 204 is set to the OFF state (S208). In this case, the controller 209 determines in S201 whether or not the optical disc apparatus is set to the standby state again. When the optical disk device is set to the standby state again (S201: YES), the same processing as described above is executed.

  On the other hand, when the reproduction operation is started before the timer measurement time T exceeds the predetermined threshold time Ts (S207: NO, S204: YES), the controller 209 controls the servo circuit 208 to focus the laser beam. The position is drawn into the recording layer to be reproduced. In response to this, the servo circuit 208 executes a focus search, and draws the focal position of the laser light into the recording layer to be reproduced (S205).

  Thereafter, the servo circuit 208 supplies a focus servo signal and a tracking servo signal to the objective lens actuator 132 in the optical pickup device 204, and executes focus servo and tracking servo for the objective lens. Further, the servo circuit 208 monitors the reproduction RF signal at the time of management information reading, and controls the aberration actuator 133 so that the reproduction RF signal becomes the best.

  Thus, when various servos are turned on, the reproducing operation for the recording layer is executed (S206). When the reproduction operation is completed, the process returns to S201, and the controller 209 again waits for the optical disc apparatus to enter a standby state.

  As described above, according to the present embodiment, when the reproduction target disc has three or more recording layers, in the standby state before the reproduction transition, the central recording of the recording layers in which the focal positions of the laser beams are arranged in the stacking direction is provided. Be drawn into the layer. For this reason, the distance between the recording layer closest to the laser beam incident surface side and the innermost recording layer farthest from the incident surface is the maximum amount of movement of the laser beam focal point during reproduction transition. It can be reduced to about half. Therefore, regardless of which recording layer is the target recording layer to be reproduced, the focal position of the laser beam can be quickly drawn into the target recording layer, and the time required to start reproduction can be shortened.

  Further, the drive amount of the expander 105 at the time of playback transition can be reduced to about half of the maximum stroke, so that the drive state of the expander 105 can be quickly adjusted to a state corresponding to the target recording layer. . Therefore, also from this point, it is possible to speed up the reproduction transition.

  In the present embodiment, when the optical disc includes three or more recording layers in the stacking direction, management for managing main information recorded on the disc in at least the central recording layer among these recording layers. It is desirable that information be recorded.

  This makes it possible to smoothly draw the focal position of the laser beam into the initial recording layer (Lp) when shifting from the initial operation (FIG. 4) when the disc is loaded to the standby state. That is, if the management information is held in the central recording layer, the central recording layer is read in S103 of FIG. 4, and this recording layer is set as the initial recording layer (Lp) in S106. . For this reason, when shifting from the initial operation of FIG. 4 to the standby state, the drawing state for the recording layer read in S103 may be continued as it is, and drawing to the initial recording layer (Lp) is performed separately. There is no need to do it. Therefore, if management information is held in the central recording layer in this way, the focal position of the laser beam can be positioned smoothly on the initial recording layer (Lp) in the standby state after the processing of FIG. 4 is completed. it can.

  FIGS. 6 and 7 are diagrams showing a configuration example of the area format when the management information is held in the central recording layer 12 (layer 1) in the disc 10 shown in FIG. FIG. 6 is a configuration example of an area format when the disk 10 is a ROM (reproduction-only) medium, and FIG. 7 is a configuration example of an area format when the disk 10 is an R (write-once) medium. is there. Here, the ROM medium and the R medium have the same area format so that they can be interchanged.

  First, referring to FIG. 6, when the disk 10 is a ROM medium, the recording layer 12 of the first layer (layer 0) from the laser light incident surface has a burst cutting area (BCA), The area is divided into a system middle area, a connection area, an inner middle area, a data area, and a data lead-out area.

  In addition, the recording layer 12 of the second layer (layer 1) from the laser light incident surface is divided into a system lead-in area, a connection area, a data lead-in area, a data area, and an outer middle area in order from the inner circumference side of the disc. The

  Further, the third recording layer 12 (layer 2) from the laser light incident surface is divided into a system middle area, a connection area, an inner middle area, a data area, and an outer middle area in order from the inner circumference side of the disc.

  In the BCA, predetermined information regarding the disc is recorded. Specifically, information such as a BCA_ID and a book number of a standard document to which the disc complies is recorded. Such information is recorded by intermittently erasing the recording layer 12 in the disk circumferential direction. Note that the disappearance of the recording layer 12 is performed, for example, by burning out using a high power laser. Note that BCA is not arranged in layers 1 and 2. In the area corresponding to the BCA of layer 1, the recording layer 12 remains as it is.

  When the beam spot is positioned on the BCA, the reflected light becomes bright and dark according to the disappeared portion and the non-disappeared portion of the recording layer 12. By demodulating this change in brightness, the information recorded in the BCA is reproduced.

  Information related to physical parameters (pit size, track pitch, etc.) of the disk 10 and management information for managing main information in the disk 10 are recorded in the system lead-in area. In the data lead-in area, the same information as the system lead-in area is recorded. In this case, the optical disc apparatus can acquire management information by accessing either the system lead-in area or the data lead-in area in S103 of FIG.

  The connection area is a flat mirror surface. Main information is recorded in the data area. Predetermined information is recorded in each of the system middle area, inner middle area, outer middle area, and data lead-out area. For example, in these areas, attribute information (area type) indicating which area of which layer belongs is recorded. This attribute information is similarly recorded in the system lead-in area, data lead-in area, and data area.

  Based on these attribute information, the optical disc apparatus can determine in which area the reproduction position is located. For example, even if the optical disc apparatus accesses the inner middle area by mistake when accessing the data lead-in area, it is possible to immediately determine the wrong access, and the access destination layer is a layer including the data lead-in (layer 1). ) Can be clearly classified.

  A pit row is formed in a spiral shape in each area on the outer peripheral side of the BCA, and a track is constituted by this pit row. Here, the track pitch of the system lead-in area and the system middle area is wider than the track pitch of each area on the outer peripheral side from the connection area. In this way, by widening the track pitch between the system lead-in area and the system middle area, in particular, information recorded in the system lead-in area (information on physical parameters and management information) can be reliably read by the optical disc apparatus. Can be. Further, by narrowing the track pitch in the outer peripheral area from the connection area, the recording density of the area can be increased, and the recording capacity of the disc can be increased.

  The pit length in each area is as shown in the table below. When the physical parameters such as the track pitch are made equal at the same radial position in this way, the S-curve for each recording layer is generated under the same physical parameter, so that the recording layer can be easily identified.

  In the disc 10, data (main information) starts to be recorded from the inner periphery of the central recording layer 12 (layer 1). The main information continues to the outermost periphery of the recording layer 12 (layer 1), and then the main information continues from the outer periphery to the inner periphery of the uppermost recording layer 12 (layer 2). Then, main information continues from the inner periphery to the outer periphery of the lowermost recording layer 12 (layer 0) and reaches the data lead-out area.

  By adopting such an optical disc configuration, the jump distance from the initial recording layer to the target recording layer and the jump distance from the target recording layer to the initial recording layer can be in the range of the maximum d1. The drive amount of the expander 105 that accompanies this can be reduced.

  At the start of reproduction, the laser beam convergence position is jumped from the initial recording layer to the target recording layer. At the end of reproduction, the laser beam convergence position is jumped from the target recording layer to the initial recording layer. As described above, the jump is performed between the initial recording layer and the target recording layer each time the reproducing operation is frequently performed, and the expander 105 is driven accordingly. At this time, if the jump distance is large, the expander 105 must be driven instantaneously with a large stroke, the amount of heat generated by the drive of the expander 105 becomes large, and dust is generated by friction or the like when the expander 105 is driven. There is a possibility that it will occur.

  On the other hand, when the central recording layer is set as the initial recording layer as described above, the jump distance in the frequently occurring jump operation can be set in the range of the maximum d1, and the drive stroke of the expander 105 can be set. Can be limited to a stroke range corresponding to the distance d1 at the maximum. Therefore, heat generation of the expander 105 can be suppressed, and generation of dust due to friction can be suppressed.

  When the disk 10 is an R (write-once) medium, the area format is the same as the area format in the case of the ROM medium shown in FIG. 6, as shown in FIG. In each area, information similar to the information recorded in each area in the case of a ROM medium is recorded.

  However, when the disk 10 is an R (write-once) medium, a spiral groove is formed in each layer in place of the pit row in the area outside the connection area. In addition to the lead-in information, various information such as recorded addresses are recorded. Even when the disk 10 is an R (write-once) medium, pit rows are formed in a spiral shape in the system lead-in area and the system middle area as in the case where the disk 10 is a ROM medium. Various information is recorded in columns.

  When the disk 10 is an R (write-once) medium, the optical disk apparatus advances recording from the inner periphery of the central recording layer 12 (layer 1) toward the outer periphery. When the data area of the recording layer 12 (layer 1) is used up for recording, the optical disc apparatus advances recording from the outer periphery to the inner periphery of the uppermost recording layer 12 (layer 2). When the data area of the recording layer 12 (layer 2) is used up for recording, recording proceeds from the inner periphery to the outer periphery of the lowermost recording layer 12 (layer 0). The optical disk device updates management information for managing main information and writes it in the data lead-in area each time recording is completed. Therefore, the latest management information is recorded in the lead-in area arranged in the central recording layer (layer 1).

  In the area format of FIGS. 6 and 7, since the system lead-in area and the data lead-in area are held in the central recording layer 12 (layer 1), the disc 10 having this area format is related to the present embodiment. When reproduced by the optical disk device, as described above, the focus position of the laser beam can be smoothly drawn into the initial recording layer (Lp) when shifting from the initial operation (FIG. 4) when the disk is loaded to the standby state.

  That is, when the disc 10 having the area format of FIGS. 6 and 7 is mounted on the optical disc apparatus, the central recording layer 12 (layer L1) is read in S103 of FIG. 4, and this recording layer 12 (layer L1) is read. Is set in the initial recording layer (Lp) in S106. For this reason, when shifting from the initial operation of FIG. 4 to the standby state, the drawing state with respect to the central recording layer 1212 (layer L1) read in S103 may be continued as it is. There is no need to perform a pull-in operation. Therefore, when the area format of the disk 10 is configured as shown in FIGS. 6 and 7, the focus position of the laser beam can be smoothly positioned on the initial recording layer (Lp) in the standby state after the processing of FIG. 4 is completed. it can.

  In the above description, the area format in the case where the disc 10 has the three recording layers 12 is shown. However, as shown in FIG. 8, the disc 10 may have four recording layers 12. When the disc 10 has four recording layers 12 as described above, the area format can be changed as shown in FIGS. 9 and 10, for example. FIG. 9 is a configuration example of an area format when the disk 10 is a ROM (reproduction-only) medium, and FIG. 10 is a configuration example of an area format when the disk 10 is an R (write-once) medium. is there.

  If the disk 10 is a ROM medium, reproduction can be performed based on information in the system lead-in area without providing a separate data lead-in unless consideration is given to compatibility with the R medium. Therefore, in the ROM medium, the data lead-in area can be omitted as appropriate from the area format.

  From this point, in the area format of FIG. 9, the data lead-in area is omitted and the data area is expanded. Here, information related to physical parameters (pit size, track pitch, etc.) of the disk 10 and management information for managing main information in the disk 10 are held in the lead-in area. In the inner middle area, the outer middle area, and the lead-out area, area attribute information is recorded as in the case of FIG. This attribute information is also held in the lead-in area. In the area format shown in FIG. 6, the data area may be expanded by omitting the data lead-in area, as in the area format shown in FIG.

  In the area format of FIG. 9, the data (main information) recording start position is the data area start position of the back recording layer 12 (layer 2) of the two central recording layers 12 (layer 1 and layer 2). Is set. The main information continues to the outermost periphery of the recording layer 12 (layer 2), and then the main information continues from the outer periphery to the inner periphery of the uppermost recording layer 12 (layer 3). The main information continues from the inner periphery to the outer periphery of the lowermost recording layer 12 (layer 0), and further, the main information continues from the outer periphery to the inner periphery of the second recording layer (layer 1) from the bottom, It reaches the data lead-out area.

  The area format in FIG. 10 (area format when the disk 10 is an R medium) is obtained by adding one recording layer (layer) to the area format in FIG. Each area of FIG. 10 holds the same information as the corresponding area of FIG. In the area format shown in FIG. 10, a system lead-in area and a data lead-in area are set in the inner periphery of the inner recording layer 12 (layer 2) of the two central recording layers 12 (layer 1 and layer 2). Has been.

  The optical disc apparatus advances the recording from the inner periphery of the central recording layer 12 (layer 2) toward the outer periphery. When the data area of the recording layer 12 (layer 2) is used up for recording, recording proceeds from the outer periphery to the inner periphery of the uppermost recording layer 12 (layer 3). When the data area of (Layer 3) is used up for recording, recording proceeds from the inner periphery to the outer periphery of the lowermost recording layer 12 (Layer 0). When the data area of the recording layer 12 (layer 0) is used up for recording, recording proceeds from the outer periphery to the inner periphery of the second recording layer 12 (layer 1) from the bottom. The optical disk device updates management information for managing main information and writes it in the data lead-in area each time recording is completed. Therefore, the latest management information is recorded in the lead-in area arranged in the central recording layer (layer 2).

  Also in the area format of FIGS. 9 and 10, since the system lead-in area and the data lead-in area are held in the central recording layer 12 (layer 2), the disk 10 having this area format is used in this embodiment. When playback is performed with such an optical disk device, the focus position of the laser beam is set to the initial recording layer (Lp) when shifting from the initial operation when the disk is mounted (FIG. 4) to the standby state, as in FIGS. Can be pulled in smoothly.

  FIG. 11 shows a processing flow when recording is performed on an unrecorded disc having three or more recording layers 12. Even when this disc is loaded, the processing flow of FIG. 4 is executed, and the number of recording layers 12 of the disc is detected.

  When the recording operation for the disc is started, the controller 209 determines the central recording layer (Lc) based on the number of recording layers detected in S102 of FIG. 4, and determines the recording layer (Lc). The recording layer (Ls) for starting recording is set (S301). Here, the central recording layer (Lc) is set based on the above equation (1) as in S105 of FIG.

  When the recording start recording layer (Ls) is set, the controller 209 controls the servo circuit 208 to draw the focal position of the laser beam into the recording start recording layer (Ls) (S302). Further, the controller 209 sets a data lead-in area in the inner periphery of the recording layer (Ls) (S303), and controls each part to record from the start of the data area following the data lead-in area toward the outer periphery of the disc. Is executed (S304).

  While executing such a recording operation, the controller 209 determines whether the recording capacity of the recording layer (Ls) has been used up for recording (S305). If the recording capacity of the recording layer (Ls) remains (S305: YES), it is determined whether the recording operation is completed (S306). If the recording operation is not completed (S306: NO), the recording layer is determined. The recording operation for (Ls) is continued (S304). On the other hand, when the recording capacity of the recording layer (Ls) is used up (S305: NO), it is determined whether there are other recordable recording layers (S307), and other recordable recording layers remain. If so (S307: YES), the controller 209 executes a pull-in operation for the next recording layer (S308), and executes recording for this recording layer (S304).

  Thereafter, when the recording operation ends (S306: YES), or when there is no recordable recording layer (S307: NO), the controller 209 generates management information for the recorded main information. Recording is performed in the data lead-in area set in the recording layer (Ls) (S309). Thereby, the process at the time of the recording is completed.

  When recording is performed according to the processing flow shown in FIG. 11, the data lead-in area is held in the central recording layer 12. For this reason, when the disc 10 is reproduced by the optical disc apparatus according to the present embodiment, as in the case of FIGS. 7 and 8, the transition from the initial operation at the time of loading the disc (FIG. 4) to the standby state is performed. The focal position of the laser beam can be smoothly drawn into the initial recording layer (Lp).

  FIG. 12 is a diagram showing a modification of the disk 10 shown in FIG. In the configuration example of FIG. 8, the distance between adjacent recording layers 12 is constant (d1). However, in the configuration example of FIG. 12, the distance d2 between the second layer and the third layer is wider than the distance d1. It has been. This makes it easy to draw the focal position of the laser beam into the third recording layer, that is, the initial recording layer (Lp) as follows.

  FIG. 13A schematically shows the state of the focus error signal when the focal position of the laser light is moved from the laser light incident surface side to the inside of the disk at a constant speed in the disk 10 shown in FIG. It is.

  As shown in the figure, the focal position of the laser beam is the first recording layer 12 (layer 0), the second recording layer 12 (layer 1), and the third recording layer 12 (layer 2) from the laser beam incident surface. When the recording layer 12 (layer 3) is reached, S-shaped curves S0, S1, S2, and S3 are generated on the focus error signal. Positions F0, F1, F2, and F3 at which these S-shaped curves S0, S1, S2, and S3 cross the reference level (the level of the focus error signal before and after the appearance of the S-shaped curve) are layer 0, layer 1, and layer 2 and the on-focus position of the laser beam with respect to the layer 3.

  Here, connecting sections MLa, MLb, and MLc exist between the generating sections L0, L1, L2, and L3 of the S-shaped curves S0, S1, S2, and S3. In such sections MLa, MLb, and MLc, the focal position of the laser beam moves in the intermediate layer 13 disposed between the recording layers 12, and ideally, the focus error signals in the sections MLa, MLb, and MLc are flat. It becomes. However, when the distance d1 between the recording layers 12 is set to about 15 to 40 μm as in the present embodiment, the focus error signals in the sections MLa, MLb, and MLc are flat as shown in FIG. It will not tilt, but will tilt at an angle while lifting from the reference level. For this reason, it becomes difficult to separate the S-shaped curve, and thus it becomes difficult to draw the focal position of the laser light into each recording layer.

  In particular, the S-shaped curves of the second recording layer (Layer 1) and the third recording layer (Layer 2) have waveforms as shown in FIG. 13A due to the influence of stray light from the upper and lower recording layers. For this reason, in the disk 10 shown in FIG. 8, it is difficult to draw the focal position of the laser beam into the second recording layer (layer 1) and the third recording layer (layer 2). For this reason, when the initial recording layer (Lp) is set as the third recording layer (layer 2) as in the above-described embodiment, it takes time to pull into the initial recording layer (Lp) in the standby state. There is a possibility that the playback operation cannot be smoothly shifted.

  On the other hand, when the distance d2 between the second layer and the third layer is increased as in the configuration example of FIG. 12, the section MLb becomes wider as shown in FIG. 13B, and the third recording layer (layer 2). ) Is easily discriminated. Therefore, the focal position of the laser beam is easily drawn into the third recording layer (layer 2).

  Further, when the distance d2 between the second layer and the third layer is increased in this way, the influence of stray light from the third recording layer (layer 2) is suppressed for the second recording layer (layer 1). In addition, with respect to the third recording layer (layer 2), the influence of stray light from the second recording layer (layer 1) is suppressed. For this reason, as shown in FIG. 13B, the waveform deterioration in the S-shaped curves of the second and third recording layers is suppressed, and the focal position of the laser beam is set on the second and third recording layers. It becomes easy to pull in.

  As described above, when the distance d2 between the second layer and the third layer is increased as in the configuration example of FIG. 12, the focal position of the laser beam is easily drawn into the third recording layer (layer 2). For this reason, when the initial recording layer (Lp) is set as the third recording layer (layer 2) as in the above-described embodiment, the initial recording layer (Lp) is quickly pulled in in the standby state. Therefore, it is possible to smoothly shift from the standby state to the reproduction operation.

  In the configuration example of FIG. 12, since the number of recording layers is four, the distance d2 between the second and third layers is widened. However, when the number of recording layers is three, five layers are used. In the above case, the same effect as described above can be obtained by widening the gap between the initial recording layer (Lp) and the recording layer at a position close to the laser light incident surface by one layer with respect to this recording layer. Can be done.

  Further, even if the interval between the initial recording layer (Lp) and the recording layer separated from the recording layer by one layer from the laser light incident surface side is widened, the S-shaped curve of the initial recording layer (Lp) is increased. Waveform deterioration can be suppressed. In this case, a flat section between the S-shaped curve for the initial recording layer (Lp) and the S-shaped curve for the recording layer separated from the recording layer by one layer from the laser light incident surface side widens. The S-shaped curve for the initial recording layer (Lp) can be discriminated smoothly. Therefore, the focal position of the laser light can be smoothly drawn into the initial recording layer (Lp).

  However, in this case, since a long flat section appears next to the S-shaped curve of the initial recording layer (Lp), after this S-shaped curve goes too far, this is the S-shaped curve of the initial recording layer (Lp). Determined. Therefore, as described above, the initial recording layer (Lp) is larger than the case where the gap between the initial recording layer (Lp) and the recording layer at a position close to the laser light incident surface by one layer is increased. ) Is a little longer.

  In the above-described embodiment, when the number of recording layers is three or more and an even number, the inner recording layer of the two central recording layers is the initial recording layer. This is because of the following reason. Is. That is, when there are four recording layers as shown in FIG. 8, for example, after two recording layers 12 are formed on each of the substrate 11 side and the substrate 14 side, they are mutually connected with the middle intermediate layer 13 as an adhesive layer. The disk 10 is formed by bonding. For this reason, the central intermediate layer 13 usually has poor optical characteristics as compared with the other intermediate layers 13, and therefore the innermost recording layer 12 in contact with the central intermediate layer 13 is the most of the four recording layers 12. Playback performance is poor. For this reason, if a jump is made to the inner recording layer 12 of the two central recording layers 12 during continuous playback, the laser beam cannot be rapidly drawn into the recording layer 12 and the continuous playback is hindered. May occur.

  At this time, if the initial recording layer is set to the front recording layer 12 out of the two central recording layers 12, a jump occurs when the recording layer 12 on the back side with poor reproduction performance is used as the target recording layer at the start of reproduction. There is a possibility, and in this case, there is a possibility that it takes time to start reproduction for the above reason. On the other hand, if the inner recording layer 12 of the two central recording layers 12 is the initial recording layer as described above, even if the target recording layer is the inner recording layer 12, the initial recording layer 12 is already the initial recording layer. Since the pull-in as the recording layer has been completed, it is not necessary to perform a new jump operation, and it is possible to smoothly shift to the reproduction operation. For this reason, in the present embodiment, when the number of recording layers is three or more and an even number, the inner recording layer of the two central recording layers is set as the initial recording layer.

  As mentioned above, although embodiment of this invention and its modification example were demonstrated, this invention is not restrict | limited to these, Moreover, various changes besides the above are possible for embodiment of this invention.

  For example, in the above embodiment, the number of recording layers is detected based on the number of S-shaped curves, but information regarding the disc type and the number of recording layers is stored in the BCA and the BCA is read. Thus, the number of recording layers may be determined. In this case, the BCA is held on the first recording layer (layer 0) from the laser light incident surface side as shown in FIGS. 6, 7, 9, and 10 so that the BCA can be read quickly and properly. It is good to make it.

  In particular, when the number of recording layers increases, the S-curve with respect to the recording layer on the back side deteriorates considerably in the state where the expander 105 is fixed due to the influence of aberration, and the focal position of the laser beam is set on the recording layer on the back side. It takes time to pull in. In this case, if the number of recording layers is detected based on the number of S-shaped curves as described above, it takes time to detect the number of layers. Therefore, when a large number of recording layers (for example, 10 layers or more) are arranged, the BCA is arranged in the foremost recording layer, and preferably the BCA is arranged in the foremost recording layer (layer 0). good.

  However, when the expander 105 is set to the back side in advance, the BCA may be set to the innermost recording layer, and the radius at which the BCA is arranged to facilitate the BCA reproduction. It is preferable not to arrange BCA in the other recording layer at the position.

  Further, information regarding the number of recording layers may be recorded in the system lead-in information, and this may be read to determine the number of recording layers. Furthermore, the number of recording layers may be determined by appropriately comparing the number of S-curves, information read from the BCA, and system lead-in information. By doing so, erroneous determination of the number of layers can be prevented.

  In the above embodiment, an R type (write-once) type disc is shown as a recordable disc. However, when three or more recording layers are arranged on an RW (Rewritable) type disc. However, recording / reproduction may be performed in the same manner as in the above embodiment, and a data format similar to the above may be applied.

  Further, the optical system of FIG. 2 is not configured to suppress stray light by a pinhole, but a pinhole is disposed between the anamorphic lens 109 and the photodetector 110 and the stray light is removed by this pinhole. May be. In this case, the pinhole is arranged at a position where the spot of reflected light from the target recording layer is minimized.

  The present invention is not limited to the optical disks shown in Table 1 and FIGS. 6, 7, 9, and 10, and can be applied to various multilayer optical disks and recording / reproducing apparatuses thereof. For example, in a multilayer optical disc in which a high NA optical system and a laser beam having a wavelength of 420 nm or less are used, the distance between layers is shortened and the influence of crosstalk is increased. The present invention is also useful in such a case. .

  In addition, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

The figure which shows the layer structure of the optical disk based on Embodiment The figure which shows the optical system of the optical pick-up apparatus which concerns on embodiment The figure which shows the structure of the optical disk apparatus which concerns on embodiment 6 is a flowchart showing an operation when a disc is loaded according to the embodiment. The flowchart which shows the operation | movement at the time of the reproduction | regeneration operation | movement which concerns on embodiment. The figure which shows the area format of the optical disk which concerns on embodiment The figure which shows the area format of the optical disk which concerns on embodiment The figure which shows the layer structure of the optical disk based on Embodiment The figure which shows the area format of the optical disk which concerns on embodiment The figure which shows the area format of the optical disk which concerns on embodiment 6 is a flowchart showing an operation during a recording operation according to the embodiment. The figure which shows the layer structure of the optical disk based on Embodiment The figure explaining the effect of the optical disk which concerns on embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical disk 12 Recording layer 204 Optical pick-up apparatus 208 Servo circuit 209 Controller

Claims (9)

An optical pickup device for irradiating the disc with laser light;
A layer number discriminating unit for discriminating the number of recording layers arranged in the disc;
A recording layer determining unit that determines a central recording layer as an initial recording layer among the recording layers arranged in the stacking direction when the number of recording layers determined by the layer number determining unit is three or more;
A reproduction preceding processing unit that controls the optical pickup device in a standby state before transition to reproduction and draws the focal position of the laser light into the initial recording layer;
An optical disc device characterized by the above. In claim 1,
When the number of recording layers arranged in the disc is three or more and an even number, the recording layer determination unit determines one of the two central recording layers as the initial recording layer,
An optical disc device characterized by the above. In claim 2,
When the number of recording layers arranged in the disc is three or more and an even number, the recording layer determination unit is the back of the two central recording layers as viewed from the laser light incident surface side. A recording layer on the side is determined as the initial recording layer,
An optical disc device characterized by the above. With three or more recording layers in the stacking direction,
Management information for managing information recorded on the disc is recorded in at least the central recording layer among these recording layers,
An optical disc characterized by the above. In claim 4,
3 or more and even number of recording layers in the stacking direction,
The management information is recorded in at least one of the two central recording layers,
An optical disc characterized by the above. In claim 5,
Of the two recording layers in the center, the management information is recorded on the recording layer on the back side when viewed from the incident surface side of the laser beam.
An optical disc characterized by the above. An optical pickup device for irradiating the disc with laser light;
A recording control unit for controlling the optical pickup device to record information on the disc;
A layer number discriminating unit for discriminating the number of recording layers arranged in the disc;
The recording control unit manages information recorded on the disc in the central recording layer among the recording layers arranged in the stacking direction when the number of recording layers determined by the layer number determination unit is 3 or more. Record management information
An optical disc device characterized by the above. In claim 7,
When the number of recording layers arranged in the disc is three or more and an even number, the recording control unit records the management information in one of the two central recording layers.
An optical disc device characterized by the above. In claim 8,
When the number of recording layers arranged in the disc is 3 or more and an even number, the recording control unit, of the two central recording layers, is the back side as viewed from the laser light incident surface side. Recording the management information on the recording layer of
An optical disc device characterized by the above.

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