JP2012208990A - Optical recording and reproducing method, optical recording and reproducing medium, and optical recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a transfer rate for recording or reproducing in a method of optical recording/reproducing on an optical recording medium having a servo layer and a recording/reproducing layer, even with an increased number of recordable/reproducible recording/reproducing layers.SOLUTION: When recording information on an optical recording medium 10 having servo layers 18 and 20 and a recording/reproducing layer, information is recorded in a first rotational direction when viewed from a first surface 10A side by irradiating a first recording/reproducing layer 14 with a first recording/reproducing beam 170A while performing tracking control by irradiating the servo layers 18 and 20 with a tracking beam 270A (a first recording operation). Further, information is recorded in a second rotational direction opposite to the first rotational direction when viewed from a second surface 30A side by irradiating a second recording/reproducing layer 34 with a second recording/reproducing beam 170B while performing tracking control using the serve layers 18 and 20 common to the first recording operation (a second recording operation).

Description

  The present invention relates to an optical recording medium having a plurality of recording / reproducing layers, an optical recording / reproducing method and an optical recording / reproducing apparatus for performing recording or reproduction on the optical recording medium.

  Conventionally, for viewing digital moving image contents and recording digital data, CD-DA, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD +/- RW, DVD-RAM, Optical recording media such as Blu-ray Disc (BD) are widely used. Among them, BD, which is one of the next-generation DVD standards, has a wavelength of laser light used for recording and reproduction as short as 405 nm, and a numerical aperture of the objective lens is set to 0.85. On the optical recording medium side corresponding to the BD standard, tracks are formed at a pitch of 0.32 μm. In this way, recording / reproducing of 25 GB or more is possible with respect to one recording / reproducing layer of the optical recording medium.

  By the way, the capacity of moving images and data is expected to increase more and more in the future. Therefore, a method for increasing the capacity of the optical recording medium by increasing the number of recording / reproducing layers in the optical recording medium has been studied. In the BD standard optical recording medium, a technique for realizing a super-large capacity of 200 GB by providing six to eight recording / reproducing layers has been reported (see Non-Patent Documents 1 and 2).

  More recently, there have been technical proposals for 20-layer ROM type optical recording media (see Non-Patent Document 3) and 10 to 16-layer write-once optical recording media (see Non-Patent Documents 4, 5, and 6). The possibility of achieving a recording capacity of about 500 GB using an optical system (wavelength and numerical aperture) similar to that of the BD standard is increasing.

  On the other hand, when the recording / reproducing layer is multilayered in the optical recording medium, if the recording / reproducing layer is formed with irregularities for tracking control such as grooves / lands, the medium configuration becomes complicated, and work such as eccentricity adjustment is performed. There is concern that it will be difficult. Further, each time a recording / reproducing layer is provided, a stamper as a mother die for forming irregularities is required, and the more layers are used, the more times the stamper is used and the higher the manufacturing cost.

  Therefore, in recent years, in an optical recording medium, a servo layer having irregularities and grooves and a recording / reproducing layer not having irregularities and grooves are provided separately, and tracking signals are obtained from the servo layer using a beam dedicated to tracking control. Techniques for recording information on a recording / reproducing layer using a recording / reproducing beam have been proposed (see Patent Documents 1, 2, and 3).

JP 2008-97693 A JP 2008-97694 A International Publication WO2008 / 099708

I. Ichimura et. Al., Appl. Opt, 45, 1974-1803 (2006) K. Mishima et.al., Proc. Of SPIE, 6282, 62820I (2006) A. Mitsumori et. Al., Jpn. J. Appl. Phys., 48, 03A055 (2009) T. Kikukawa et. Al., Jpn. J. Appl. Phys., 49, 08KF01 (2010) M. Inoue et. Al., Proc.SPIE, 7730, 77300D (2010) M. Ogasawara et. Al., Tech. Dig. Of International Symposium on Optical Memory 2010, 224 (2010)

  When the number of recording / reproducing layers is increased as in the above-described technique, the capacity of the optical recording medium increases, but this alone does not lead to an improvement in the recording / reproducing speed. For example, when the recording capacity of the optical recording medium is increased, but the recording speed is not improved, the waiting time of the user in the recording work becomes long and the sensory convenience is lowered.

  When the number of recording / reproducing layers is increased as in the above technique, the recording / reproducing layers are arranged over a wide range in the thickness direction in the optical recording medium. As a result, the optical pickup for recording / reproducing needs to focus the beam in a wide range in the thickness direction, so the correction range of spherical aberration must be set wide. Therefore, the configuration of the optical pickup becomes complicated and large, and the seek time of the recording / reproducing layer by the optical pickup becomes long.

  In addition, as in Patent Documents 1 to 3, if an attempt is made to increase the number of recording / reproducing layers by forming a plurality of servo layers, the recording / reproducing layers and the spacer layers are alternately laminated at the time of manufacturing the optical recording medium. The manufacturing process becomes complicated because of the process. Further, when a plurality of servo layers are formed on one side of the optical recording medium, the internal stress during film formation tends to be shifted to one side of the optical recording medium, so that the optical recording medium is likely to be warped or distorted. there were.

  The present invention has been made in view of the above-mentioned problems. For an optical recording medium having a servo layer and a recording / reproducing layer, the transfer rate at the time of recording or reproducing is increased while increasing the number of recording / reproducing layers. An object of the present invention is to provide an improved optical recording / reproducing technique.

  The above-mentioned object is achieved by the following means by the inventors' extensive research.

  That is, the present invention that achieves the above-described object includes a servo layer having irregularities or grooves for tracking control, and an irregularity for tracking control that is pre-laminated or formed on the first surface side with respect to the servo layer. A plurality of first recording / reproducing layers that are not laminated, and a plurality of second recording / reproducing layers that are pre-laminated on the second surface side with respect to the servo layer or formed afterwards and that do not have irregularities for tracking control, An optical recording / reproducing method for recording / reproducing information on / from an optical recording medium having a tracking beam by irradiating the servo layer with a tracking beam and performing tracking control from the first surface to the first recording / reproducing layer By irradiating the first recording / reproducing beam, the first recording operation for recording information in the first rotation direction as viewed from the first surface side is performed simultaneously with the first recording operation, and the first recording operation is performed. 1 While performing tracking control using the servo layer that is common to the operation, the second recording / reproducing layer is irradiated with a second recording / reproducing beam from the second surface, as viewed from the second surface side. An optical recording / reproducing method for an optical recording medium, comprising: a second recording operation for recording information in a second rotation direction opposite to the first rotation direction.

  In the optical recording / reproducing method for achieving the above object, the first recording operation and the second recording operation are simultaneously performed while maintaining the first recording / reproducing beam and the second recording / reproducing beam in a substantially coaxial state. It is characterized by performing.

  The optical recording / reproducing method that achieves the above-described object is characterized in that the first recording operation and the second recording operation are simultaneously performed by irradiating the servo layer with the common tracking beam.

  In the optical recording / reproducing method for achieving the above object, data to be recorded on the optical recording medium is recorded on the first recording operation side by the digital signal processing device for controlling the first and second recording / reproducing beams. The data is divided into data and second data on the second recording operation side.

  In the optical recording / reproducing method for achieving the above object, the optical recording medium includes, as the servo layer, a first servo layer having the unevenness or groove for tracking control in a first spiral direction, and the first spiral direction. And a second servo layer having the tracking control irregularities or grooves in the opposite second spiral direction, and using the common first servo layer from the inner circumference side to the outer circumference side of the optical recording medium And performing the first recording operation and the second recording operation while performing tracking control toward the optical disk, and from the outer peripheral side to the inner peripheral side of the optical recording medium using the common second servo layer. A step of performing the first recording operation and the second recording operation while performing tracking control.

  In the optical recording / reproducing method for achieving the above object, the wavelength of the tracking beam and the wavelength of the first or second recording / reproducing beam are different from each other.

  In the optical recording / reproducing method for achieving the above object, the wavelength of the first or second recording / reproducing beam is in a range of 380 to 450 nm.

  To achieve the above object, the present invention provides a first servo layer having the tracking control irregularities or grooves in the first spiral direction, and the tracking control irregularities or grooves in the second spiral direction opposite to the first spiral direction. A second servo layer having a groove, and a plurality of first recording / reproducing layers which are laminated in advance on the first surface side with respect to the first and second servo layers or are formed afterwards and have no unevenness for tracking control And a plurality of second recording / reproducing layers which are previously laminated on the second surface side with respect to the first and second servo layers or are formed afterwards and have no unevenness for tracking control. And an optical recording medium.

  The present invention that achieves the above-described object includes a servo layer having irregularities or grooves for tracking control, and a layer laminated in advance or formed on the first surface side with respect to the servo layer, and has irregularities for tracking control. A plurality of first recording / reproducing layers that are not stacked, and a plurality of second recording / reproducing layers that are laminated in advance on the second surface side with respect to the servo layer or are formed afterwards and have no unevenness for tracking control. A recording / reproducing apparatus for recording / reproducing information on / from an optical recording medium, the tracking optical system for irradiating the servo layer with a tracking beam, and tracking control using the tracking optical system, First recording / reproducing light that irradiates the first recording / reproducing layer from one surface to the first recording / reproducing layer and records information in the first rotation direction when viewed from the first surface side. System and the first recording / reproducing optical system, recording is performed simultaneously, tracking control using the tracking optical system is performed, and from the second surface to the second recording / reproducing layer A second recording / reproducing optical system that irradiates a second recording / reproducing beam and records information in a second rotation direction opposite to the first rotation direction when viewed from the second surface side. An optical recording / reproducing apparatus for an optical recording medium is characterized.

  The optical recording / reproducing apparatus that achieves the above object includes a first linear motion mechanism that moves both the first recording / reproducing optical system and the tracking optical system in a tracking direction, and tracking the second recording / reproducing optical system. A second linear motion mechanism that moves in a direction, and the second linear motion mechanism is controlled using the tracking signal in the tracking optical system.

  The optical recording / reproducing apparatus that achieves the above object includes: first data for recording data to be recorded on the optical recording medium on the first recording / reproducing layer by the first recording / reproducing optical system; and the second recording / reproducing device. And a second signal to be recorded on the second recording / reproducing layer by an optical system.

  According to the present invention, with respect to an optical recording medium having a servo layer and a recording / reproducing layer, the transfer rate during recording or reproduction can be improved while increasing the number of recording / reproducing layers.

1 is a block diagram showing an overall configuration of an optical recording / reproducing apparatus and an optical recording medium for realizing an optical recording / reproducing method according to an embodiment of the present invention. It is a block diagram which shows the example of an internal structure of the 1st optical pick-up of the same optical recording / reproducing apparatus. It is a block diagram which shows the example of an internal structure of the 2nd optical pick-up of the same optical recording / reproducing apparatus. It is sectional drawing which shows the laminated structure of the same optical recording medium. It is sectional drawing which shows the manufacturing procedure of the optical recording medium. It is sectional drawing which shows the manufacturing procedure of the optical recording medium. It is sectional drawing which shows the manufacturing procedure of the optical recording medium. It is sectional drawing which shows the manufacturing procedure of the optical recording medium. It is sectional drawing which shows the manufacturing procedure of the optical recording medium. It is sectional drawing which expands and shows the recording procedure to the optical recording medium by the same optical recording / reproducing method. It is sectional drawing which expands and shows the recording procedure to the optical recording medium by the same optical recording / reproducing method. It is sectional drawing which expands and shows the reproduction | regeneration procedure of the optical recording medium by the same optical recording / reproducing method. It is a perspective view which shows the recording / reproducing procedure to the optical recording medium by the same optical recording / reproducing method. It is sectional drawing which expands and shows the other reproduction | regeneration procedure of the optical recording medium by the same optical recording / reproducing method. It is sectional drawing which shows the other laminated structure example of the optical recording medium with which the same optical recording / reproducing method is applied. It is sectional drawing which shows the other laminated structure example of the optical recording medium with which the same optical recording / reproducing method is applied. It is sectional drawing which shows the other laminated structure example of the optical recording medium with which the same optical recording / reproducing method is applied. It is sectional drawing which shows the other laminated structure example of the optical recording medium with which the same optical recording / reproducing method is applied.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an optical recording medium 10 to which an optical recording / reproducing method according to an embodiment of the present invention is applied, and an internal configuration of an optical recording / reproducing apparatus 70 that realizes the optical recording / reproducing method. The recording / reproducing apparatus 70 includes first and second optical pickups 90A and 90B, first and second linear motion mechanisms 75A and 75B that move the first and second optical pickups 90A and 90B in the tracking direction, User information to be recorded or reproduced is input / output between the tracking control device 80 that controls the first and second linear motion mechanisms 75A and 75B and an external information device, and recorded data or reproduction to / from the optical recording medium 10 is performed. A digital signal processing device 86 for controlling data is provided.

  The first and second linear motion mechanisms 75A and 75B are so-called linear motors, on which the first and second optical pickups 90A and 90B are mounted. As a result, the first optical pickup 90A is moved in the radial direction of the optical recording medium 10 by the first linear motion mechanism 75A. The second optical pickup 90B is moved in the radial direction of the optical recording medium 10 by the second linear motion mechanism 75B.

  The first optical pickup 90A irradiates a beam from one first surface 10A side of the optical recording medium 10. The second optical pickup 90B irradiates the beam from the other second surface 30A side of the optical recording medium 10. Although not particularly illustrated, the optical axis of the first optical pickup 90A and the optical axis of the second optical pickup 90B are coaxial.

  The internal configurations of the first and second optical pickups 90A and 90B are partially the same and partially different. Accordingly, with respect to parts / members that are common to each other, the first optical pickup 90A adds A to the end of each symbol in the drawing or text, and the second optical pickup 90B uses B at the end of the symbol in the drawing or text. And the same number except for the end. Here, the internal configuration of the first optical pickup 90A will be described in detail, and the second optical pickup 90B will be described focusing on differences from the first optical pickup 90A.

  As shown in FIG. 2, the first optical pickup 90A includes a recording / reproducing optical system 100A and a tracking optical system 200A. The recording / reproducing optical system 100A is an optical system that performs recording / reproduction with respect to the first recording / reproducing layer group 14 of the optical recording medium 10. The tracking optical system 200A performs tracking control using the first and second servo layers 18 and 20 when recording information on the first recording / reproducing layer group 14 using the recording / reproducing optical system 100A. It becomes an optical system.

  The divergent recording / reproducing beam 170A emitted from the light source 101A of the recording / reproducing optical system 100A is transmitted through the collimator lens 153A provided with the spherical aberration correcting means 193A and is incident on the polarization beam splitter 152A. The beam 170A has a blue wavelength of 380 to 450 nm (here, 405 nm). The beam 170A incident on the polarization beam splitter 152A is transmitted through the polarization beam splitter 152A and further converted into circularly polarized light by transmission through the quarter-wave plate 154A, and then enters the beam splitter 260A of the tracking optical system 200A. Incident. The beam splitter 260A is set to have a high transmittance and a low reflectance. Specifically, the ratio of the transmittance to the reflectance is set to 10 times or more. Accordingly, the beam 170A passes through the beam splitter 260A and is converted into a convergent beam by the objective lens 156A. The beam 170A is focused on one of the first recording / reproducing layer groups 14 formed in the optical recording medium 10 and targeted for recording / reproducing.

  The aperture of the objective lens 156A is limited by the aperture 155A, and the numerical aperture NA is 0.70 to 0.90 (here, 0.85). For example, the beam 170A reflected by the first recording / reproducing layer group 14 passes through the objective lens 156A, the beam splitter 260A, and the quarter-wave plate 154A and is converted into linearly polarized light that is 90 degrees different from the forward path. Reflected by the polarization beam splitter 152A.

  The beam 170A reflected by the polarization beam splitter 152A passes through the condenser lens 159A, is converted into convergent light, and enters the photodetector 132A through the cylindrical lens 157A. Astigmatism is given to the beam 170A when it passes through the cylindrical lens 157A.

  The photodetector 132A has four light receiving units (not shown) and outputs a current signal corresponding to the amount of light received. From these current signals, a focus error (hereinafter referred to as FE) signal by an astigmatism method, a tracking error (hereinafter referred to as TE) signal by a push-pull method limited at the time of reproduction, and reproduction of information recorded on the optical recording medium 10 A signal or the like is generated. The FE signal and the TE signal are amplified and phase compensated to a desired level, and then fed back to the actuators 191A and 192A. The actuators 191A and 192A perform tilt control, tracking control, focus control, and the like for the objective lens 156A. The tracking error signal from the recording / reproducing optical system 100A is used only during reproduction.

  A divergent tracking control beam 270A having a red wavelength of 630 to 680 nm (here, 650 nm) emitted from the light source 201A of the tracking optical system 200A is transmitted through a collimator lens 253A including a spherical aberration correction unit 293A. , And enters the polarizing beam splitter 252A. The beam 270A incident on the polarization beam splitter 252A is transmitted through the polarization beam splitter 252A, further transmitted through the quarter-wave plate 254A, converted into circularly polarized light, and then reflected by the beam splitter 260A. The beam 270A is further converted into a convergent beam by the objective lens 156A, and is focused on one of the first and second servo layers 18 and 20 formed inside the optical recording medium 10. The beam 270A reflected by the first and second servo layers 18 and 20 passes through the objective lens 156A, is reflected by the beam splitter 260A, and is converted into linearly polarized light that is 90 degrees different from the forward path in the quarter-wave plate 254A. Then, the light is further reflected by the polarization beam splitter 252A. The beam 270A reflected by the polarizing beam splitter 252A passes through the condenser lens 259A, is converted into convergent light, and enters the photodetector 232A via the cylindrical lens 257A. Astigmatism is given to the beam 270A when passing through the cylindrical lens 257A.

  The photodetector 232A has four light receiving units (not shown), and outputs a current signal corresponding to the amount of light received. From these current signals, a tracking error (TE) signal is generated by the push-pull method. If information is also recorded on the first and second servo layers 18 and 20, a reproduction signal may be generated from this current signal. On the photodetector 232A side, it is not necessary to generate a focus error (FE) signal. Of course, a focus error (FE) signal may be generated.

  As already described, the beam splitter 260A is set to have a high transmittance and a low reflectance. Accordingly, a part of the return light emitted from the light source 101A of the recording / reproducing optical system 100A and reflected by any of the first recording / reproducing layer group 14 is reflected by the beam splitter 260A and proceeds to the tracking optical system 200A side. . On the other hand, most of the return light emitted from the light source 201A of the tracking optical system 200A and reflected by the first and second servo layers 18 and 20 is transmitted through the beam splitter 260A to the recording / reproducing optical system 100A side. There is a possibility to go forward. In the recording / reproducing optical system 100A and the tracking optical system 200A, even if both return lights are mixed, the recording / reproducing optical system 100A and the tracking optical system 200A have different focal points in the optical recording medium 10. Because of the position, the spread angles of the beams 170A and 270A are different. Therefore, the influence of mixing is removed by extracting only one of the beams 170A and 270A using a slit or aperture having a fixed shape (not shown) and then entering the light detectors 132A and 232A. Of course, the beams 170A and 270A may be separated by a filter having wavelength selectivity.

  In particular, the difference between the focal position of the beam 170A in the optical recording medium 10 in the recording / reproducing optical system 100A and the focal position in the optical recording medium 10 of the beam 270A of the tracking optical system 200A is always within a certain range. By doing so, the above-mentioned slits and apertures can be made simple, so that the beam can be more easily separated. In order to stabilize the difference in focal length, it can be said that the closer the focal position of the recording / reproducing beam 170A and the focal position of the servo beam 270A are, the smaller the error is.

  As shown in FIG. 3, the second optical pickup 90B includes a recording / reproducing optical system 100B, but does not include a tracking optical system. The recording / reproducing optical system 100B is an optical system that performs recording / reproducing with respect to the second recording / reproducing layer group 34 of the optical recording medium 10. The recording / reproducing optical system 100B has substantially the same configuration as the recording / reproducing optical system 100A of the first optical pickup 90A.

  When information is recorded on the second recording / reproducing layer group 34 by the recording / reproducing optical system 100B of the second optical pickup 90B, the tracking optical system 200A of the first optical pickup 90A is connected to the first and second servo layers 18, A tracking error (TE) signal obtained by irradiating 20 is used. Specifically, the actuators 191B and 192B perform tilt control, tracking control, focus control, and the like on the objective lens 156B using the tracking error signal.

  Returning to FIG. 1, the tracking control device 80 includes an access controller 82, a first driver 84A, and a second driver 84B. The access controller 82 controls the actuators 191A, 191B, 192A, 192B of the first and second optical pickups 90A, 90B, and uses the first driver 84A and the second driver 84B to reach the target tracking position. The first linear motion mechanism 75A and the second linear motion mechanism 75B are controlled.

  Specifically, the access controller 82 controls the first and second optical pickups 90A and 90B as follows.

  (Control of access controller at the time of recording) The access controller 82 receives a recording / reproducing layer to be recorded and its tracking number from a digital signal processing device 86 to be described later, and the recording / reproducing layer to be recorded becomes the first servo layer. 18 is used to determine whether recording / reproduction is performed or whether recording / reproduction is performed using the second servo layer 20. Further, the access controller 82 applies the tracking beam 270A of the first optical pickup 90A to the land / groove corresponding to the tracking number of either the first or second servo layer 18 or 20 obtained from the determination result. Irradiate. This is achieved by the access controller 82 receiving the tracking error (TE) signal from the beam 270A of the tracking optical system 200A and feedback-controlling the actuators 191A and 192A and the first linear motion mechanism 75A. In this state, the first optical pickup 90A records information by irradiating the first recording / reproducing layer group 14 with a recording / reproducing beam 170A.

  At the same time, the access controller 82 controls the actuators 191A and 192A and the second linear motion mechanism 75B using the tracking error (TE) signal of the first optical pickup 90A. That is, the actuators 191A, 191B, 192A, 192B, the first linear motion mechanism 75A, and the second linear motion mechanism 75B perform the same operation in the tracking direction. In this state, the second optical pickup 90B irradiates the second recording / reproducing layer group 34 with a recording / reproducing beam 170B to record information. As a result, in the present embodiment, the first and second optical pickups 90A and 90B are simultaneously tracking-controlled while using the common first and second servo layers 18 and 20, and the first and second recording / reproducing layer groups 14 are controlled. , 34 simultaneously record information.

  (Control of Access Controller during Reproduction) The first recording / reproducing layer group 14 is reproduced by irradiating the first recording / reproducing layer group 14 with the beam 170A of the recording / reproducing optical system 100A of the first optical pickup 90A. In this tracking control, the access controller 82 directly uses the tracking error (TE) signal of the recording / reproducing beam 170A without using the tracking beam 270A, and the actuators 191A, 192A and the first straight line are used. This is realized by feedback control of the moving mechanism 75A.

  The second recording / reproducing layer group 34 is reproduced by irradiating the second recording / reproducing layer group 34 with the beam 170B of the recording / reproducing optical system 100B of the second optical pickup 90B. In this tracking control, the access controller 82 feeds back the actuators 191B and 192B and the second linear motion mechanism 75B by directly using the tracking error (TE) signal of the recording / reproducing beam 170B of the second optical pickup 90B. Realized by controlling. That is, in the present embodiment, the first and second optical pickups 90A and 90B are separately subjected to tracking control, and information of the first and second recording / reproducing layer groups 14 and 34 is reproduced simultaneously.

  The digital signal processing device 86 includes a reproduction processing unit 87A, a recording processing unit 87B, a division / synthesis processing unit 87C, and an input / output interface unit 87D.

  The reproduction processing unit 87A reproduces information recorded on the optical recording medium 10 by controlling the power of the light sources 101A and 101B of the first and second optical pickups 90A and 90B to a predetermined reproduction level. Further, the analog reproduction signals of the first and second optical pickups 90A and 90B are received, and the analog signals are converted into digital signals.

  Specifically, the reproduction processing unit 87A decodes an analog signal into a digital signal by an A / D converter, a PR equalizer, an ML decoder, and the like (not shown). The A / D converter converts the reproduced waveform into a digital value. In the PR equalizer, the digital value is sampled, and equalization processing is performed so that the voltage level approaches the PR reference class characteristic. In the ML decoder, the maximum likelihood ideal response is selected from the signals equalized by the PR equalizer, and a binarized digital signal is generated. As a result, the information recorded in the first recording / reproducing layer group 14 is reproduced by the first optical pickup 90A to become digitized first data. Further, the information recorded in the second recording / reproducing layer group 34 is reproduced by the second optical pickup 90B to become digitized second data. The first and second data are transferred to the division / synthesis processing unit 87C.

  The recording processor 87B records and erases information on the optical recording medium 10 by individually controlling the power of the light sources 101A and 101B of the first and second optical pickups 90A and 90B based on a predetermined recording strategy. Or Specifically, the first data is recorded in the first recording / reproducing layer group 14 by controlling the recording power of the light source 101A of the first optical pickup 90A. Further, the recording power of the light source 101B of the second optical pickup 90B is controlled to record the second data on the second recording / reproducing layer group. The first data and the second data are received from the division / combination processing unit 87C.

  The division / combination processing unit 87C divides the recording schedule data received from the input / output interface unit 87C into first data and second data, and transmits the data to the recording processing unit 87B. Also, the division / combination processing unit 87C combines the first data and the second data received from the reproduction processing unit 87A into one reproduction data, and transmits this reproduction data to the input / output interface unit 87C.

  The input / output interface unit 87C performs input / output of information with an external information device. Specifically, data to be recorded is received from an external information device, or reproduction data of the optical recording medium 10 is output to the external information device.

  FIG. 4 shows an enlarged cross-sectional structure of the optical recording medium 10 of the present embodiment.

  The optical recording medium 10 has a disk shape with an outer diameter of about 120 mm and a thickness of about 1.2 mm. The optical recording medium 10 includes, in order from the first surface 10A side, a first cover layer 11, a first recording / reproducing layer group 14, a first intermediate layer group 16, a first buffer layer 17, a first servo layer 18A, and a servo. The intermediate buffer layer 19, the second servo layer 20, the support substrate 12, the second buffer layer 37, the second recording / reproducing layer group 34, the second intermediate layer group 36, the second cover layer 31, and the second surface 30A are provided. Is done.

  Here, the first recording / reproducing layer group 14 includes L0 to L5 recording / reproducing layers 14A to 14F, and has a structure capable of recording information in each of them. The L0 to L5 recording / reproducing layers 14A to 14F have a planar structure having no unevenness or grooves for tracking control, and when a recording beam 170 having high energy is irradiated from the recording / reproducing optical system 100. A recording mark is formed. The types of the first recording / reproducing layer group 14 include a recordable recording / reproducing layer in which information can be additionally written but cannot be rewritten, and a rewritable recording / reproducing layer in which information can be rewritten.

  The support substrate 12 is a disk-shaped substrate having a thickness in the range of 10 μm to 1200 μm, preferably 10 μm to 600 μm, in order to ensure the thickness (about 1.2 mm) required for the optical recording medium. Specifically, in the present embodiment, the thickness of the support substrate 12 is set to 500 μm and the diameter is set to 120 mm. On the first surface 10A side of the support substrate 12, lands 20A and grooves 20B are spirally formed from the vicinity of the center toward the outer edge. The land 20A and the groove 20B become the future second servo layer 20 and are used for tracking control.

  Note that various materials can be used as the material of the support substrate 12, and for example, glass, ceramics, and resins can be used. Of these, a resin is preferred from the viewpoint of ease of molding. Examples of the resin include polycarbonate resin, olefin resin, acrylic resin, epoxy resin, polystyrene resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, and urethane resin. Among these, polycarbonate resin and olefin resin are particularly preferable from the viewpoint of processability.

  The second servo layer 20 formed on the support substrate 12 includes tracking control irregularities (land 20A and groove 20B) formed on the surface of the support substrate 12, and a reflective layer formed thereon. Consists of. In particular, in the present embodiment, a metal film such as Al or Ag is formed as a reflective layer, and functions as a simple light reflecting film. The second servo layer 20 is designed to have a transmittance of 10% or less when the tracking beam 270A of the first optical pickup 90A is irradiated. As a result, it is avoided that the beam 270A leaks out to the opposite side and becomes a noise component on the second optical pickup 90B side. In addition, when providing the recording film which can record information in addition to a reflective function, it is good also as a film | membrane structure substantially the same as recording-reproducing layers 14A-14F mentioned later.

  The pitch P1 between adjacent lands 20A or grooves 20B in the second servo layer 20 is set to be less than 0.74 μm here. Specifically, the pitch P1 is desirably set in the range of 0.6 μm to 0.7 μm, and more preferably set in the vicinity of 0.64 μm. The pitch P1 (around 0.64 μm) between the lands 20A / grooves 20B of the second servo layer 20 is large enough to allow sufficient tracking with the beam 270A in the relatively long red wavelength region. In the present embodiment, tracking is performed using both the land 20A and the groove 20B. As a result, with respect to the pitch P1 of the second servo layer 20, the track pitch P2 of the recording mark is set to be less than 0.37 μm, desirably within the range of 0.26 μm to 0.35 μm, more preferably the pitch. It is set in the vicinity of 0.32 μm, which is half (1/2) of P1. As a result, the track pitch P2 between the recording marks is about 0.32 μm which is compatible with the BD standard. Thus, by performing tracking control using the land 20A and the groove 20B, the track pitch P2 of the recording marks of the recording / reproducing layer group 14 can be reduced without reducing the pitch P2 of the second servo layer 20. .

  The inter-servo buffer layer 19 is made of a light-transmitting acrylic ultraviolet curable resin on the surface of the second servo layer 20. This film thickness is set to 30 μm, for example. On the surface of the inter-servo buffer layer 19, lands 18 </ b> A and grooves 18 </ b> B are spirally formed by using a light-transmitting resin stamper. The land 18 </ b> A and the groove 18 </ b> B become irregularities (grooves) for tracking control of the first servo layer 18. The spiral direction of the land 18A and the groove 18B is opposite to the spiral direction of the land 20A and the groove 20B in the second servo layer 20.

  The first servo layer 18 formed on the inter-servo buffer layer 19 is formed on the unevenness (land 18A and groove 18B) for tracking control formed on the surface of the inter-servo buffer layer 19, and on that. Consists of a reflective layer. Here, a metal film such as Al or Ag is formed as a reflective layer by sputtering, and functions as a simple light reflection film. The first servo layer 18 is set to have a higher transmittance than the second servo layer 20. In addition, when providing the recording film which can record information in addition to a reflective function, it is good also as a film | membrane structure substantially the same as recording-reproducing layers 14A-14F mentioned later.

  The pitch P <b> 1 between adjacent lands 18 </ b> A or grooves 18 </ b> B in the first servo layer 18 is matched with that of the second servo layer 20. Specifically, it is set in the vicinity of 0.64 μm.

  The first buffer layer 17 is made of a light-transmitting acrylic ultraviolet curable resin and has a film thickness of 208 μm. The first buffer layer 17 is made of a material that increases the amount of light absorption as the wavelength of the beam is shorter. By doing so, the light absorption amount of the blue wavelength beam 170A is large and the absorption amount of the red wavelength beam 270A is small. As a result, the first buffer layer 17 can suppress the amount of light that the blue wavelength beam 170A reaches the servo layer 18 and reflects, thereby reducing signal noise during reproduction. On the other hand, the first buffer layer 17 actively transmits the red wavelength beam 270A, thereby increasing the amount of the tracking signal.

  In the first recording / reproducing layer group 14 (L0 to L5 recording / reproducing layers 14A to 14F) laminated on the first surface 10A side of the first buffer layer 17, dielectric films are laminated on both outer sides of the write-once recording film, respectively. It has a three-layer structure (not shown). The L0 to L5 recording / reproducing layers 14A to 14F have a light reflectance, an absorptivity, a transmittance and the like for the beam 170A in the blue wavelength region (short wavelength) in the recording / reproducing optical system 100A of the first optical pickup 90A. Has been optimized.

  In addition to the basic function of protecting the write-once recording film, the dielectric film of each recording / reproducing layer also plays a role of expanding the difference in optical characteristics before and after the formation of the recording mark.

  When the beam 170A is irradiated, if the energy absorbed by the dielectric film is large, the recording sensitivity is likely to be lowered. Therefore, in order to prevent this, it is preferable to select a material having a low absorption coefficient (k) in the wavelength region of 380 nm to 450 nm (particularly 405 nm) as the material of these dielectric films. In the present embodiment, TiO 2 is used as the material for the dielectric film.

  The write-once recording film sandwiched between the dielectric films is a film on which an irreversible recording mark is formed, and the reflectance with respect to the beam 170A is greatly different between the portion where the recording mark is formed and the other portion (blank region). . As a result, data can be recorded / reproduced.

  The write-once recording film is formed mainly of a material containing Bi and O. This write-once recording film functions as an inorganic reaction film, and the reflectance is greatly different due to a chemical or physical change caused by the heat of laser light. Specific materials include Bi-O as the main component, or Bi-MO (where M is Mg, Ca, Y, Dy, Ce, Tb, Ti, Zr, V, Nb, Ta). , Mo, W, Mn, Fe, Zn, Al, In, Si, Ge, Sn, Sb, Li, Na, K, Sr, Ba, Sc, La, Nd, Sm, Gd, Ho, Cr, Co, Ni And at least one element selected from Cu, Ga, and Pb). In this embodiment, Bi—Ge—O is used as the material of the write-once recording film.

  Here, the case where the write-once recording film is employed in the L0 to L5 recording / reproducing layers 14A to 14F is shown, but a phase change recording film capable of repeated recording can also be employed. In this case, the phase change recording film preferably contains SbTeGe as a main component.

  The first intermediate layer group 16 includes L0 to L4 intermediate layers 16A to 16E in order from the side far from the first surface 10A, and is laminated between the L0 to L5 recording / reproducing layers 14A to 14F. Each of the intermediate layers 16A to 16E is made of an acrylic or epoxy ultraviolet curable resin. The film thicknesses of the L0 to L4 intermediate layers 16A to 16E are preferably set to 20 μm or less in order to increase the number of stacked layers, the L0 intermediate layer 16A is 16 μm, the L1 intermediate layer 16B is 12 μm, and the L2 intermediate layer 16C is 16 μm, the L3 intermediate layer 16D is 12 μm, and the L4 intermediate layer 16E is 16 μm. That is, intermediate layers having two kinds of film thicknesses (16 μm and 12 μm) are alternately stacked. As a result, as the interlayer distance between the L0 to L5 recording / reproducing layers 14A to 14F, the first distance (16 μm) and the second distance (12 μm) different from the first distance are alternately set in order from the light incident surface side. It will be. The difference between the first distance and the second distance is set to 4 μm. In this way, interlayer crosstalk is reduced. Of course, all the intermediate layer groups 16 may have the same film thickness.

  The first cover layer 11 is made of a light-transmitting acrylic ultraviolet curable resin, like the first intermediate layer group 16, and has a film thickness of 40 μm.

  The second buffer layer 37 formed on the second surface 30 </ b> A side of the support substrate 12 is made of a light-transmitting acrylic ultraviolet curable resin, and has a film thickness of the inter-servo buffer layer 19 and the first buffer. The total value of the layers 17 is set to 238 μm.

  In the second recording / reproducing layer group 34 (L0 to L5 recording / reproducing layers 34A to 34F) laminated on the second surface 30A side of the second buffer layer 37, dielectric films are laminated on both outer sides of the write-once recording film, respectively. It has a three-layer structure (not shown). The L0 to L5 recording / reproducing layers 34A to 34F have a light reflectance, absorptivity, transmittance, etc., for the blue wavelength region (short wavelength) beam 170B in the recording / reproducing optical system 100B of the second optical pickup 90B. Has been optimized.

  The second intermediate layer group 36 includes L0 to L4 intermediate layers 36A to 36E in order from the side far from the second surface 30A, and is laminated between the L0 to L5 recording / reproducing layers 34A to 34F. Each of the intermediate layers 36A to 36E is made of an acrylic or epoxy ultraviolet curable resin. The film thicknesses of the intermediate layers 36A to 36E are preferably set to 20 μm or less in order to increase the number of stacked layers. The L0 intermediate layer 36A is 16 μm, the L1 intermediate layer 36B is 12 μm, the L2 intermediate layer 36C is 16 μm, L3 The intermediate layer 36D is 12 μm, and the L4 intermediate layer 36E is 16 μm. That is, intermediate layers having two kinds of film thicknesses (16 μm and 12 μm) are alternately stacked. As a result, as the interlayer distance between the L0 to L5 recording / reproducing layers 34A to 34F, the first distance (16 μm) and the second distance (12 μm) different from the first distance are alternately set in order from the second surface 30A side. Will be. The difference between the first distance and the second distance is set to 4 μm. In this way, interlayer crosstalk is reduced. Of course, all the second intermediate layer groups 36 may have the same film thickness.

  The materials of the second recording / reproducing layer group 34 and the second intermediate layer group 36 are the same as those of the first recording / reproducing layer group 14 and the first intermediate layer group 16, and thus description thereof is omitted.

  The second cover layer 31 is made of a light-transmitting acrylic ultraviolet curable resin, like the second intermediate layer group 36, and has a thickness of 40 μm.

  As a result of the above configuration, the boundary (second servo layer 20) between the support substrate 12 and the first buffer layer 17 in the optical recording medium 10 is located at a distance of 350 μm from the first surface 10A. The first servo layer 18 is located at a distance of 320 μm from the first surface 10A.

  The L0 recording / reproducing layer 14A farthest from the first surface 10A in the first recording / reproducing layer group 14 is located at a distance of 112 μm from the first surface 10A, and the L1 recording / reproducing layer 14B is 96 μm from the first surface 10A. The L2 recording / reproducing layer 14C is 84 μm from the first surface 10A, the L3 recording / reproducing layer 14D is 68 μm from the first surface 10A, the L4 recording / reproducing layer 14E is 56 μm from the first surface 10A, and L5 closest to the first surface 10A. The recording / reproducing layer 14F is located at a distance of 40 μm from the first surface 10A. The overall thickness of the first recording / reproducing layer group 14 (distance between the L0 recording / reproducing layers 14A to L5 recording / reproducing layer 14F) is 72 μm. .

  In the second recording / reproducing layer group 34, the L0 recording / reproducing layer 34A farthest from the second surface 30A is located at a distance of 112 μm from the second surface 30A, and the L1 recording / reproducing layer 34B is the second surface 30A. To 96 μm, the L2 recording / reproducing layer 34C from the second surface 30A to 84 μm, the L3 recording / reproducing layer 34D from the second surface 30A to 68 μm, the L4 recording / reproducing layer 34E from the second surface 30A to 56 μm, and the second surface 30A The near L5 recording / reproducing layer 34F is located at a distance of 40 μm from the second surface 30A. The overall thickness of the second recording / reproducing layer group 34 (distance between the L0 recording / reproducing layers 34A to L5 recording / reproducing layer 34F) is 72 μm.

  That is, the optical recording medium 10 has a symmetrical structure in the thickness direction, except that the first and second servo layers 18 and 20 are arranged asymmetrically. As a result, since internal stress generated during the production of the optical recording medium 10 is generated symmetrically in the thickness direction, warpage and deformation can be reduced. In particular, even if the support substrate 12 is made thinner than 700 μm, here 100 μm, it is possible to suppress warping and deformation of the optical recording medium 10.

  Next, a method for manufacturing the optical recording medium 10 of this embodiment will be described.

  As shown in FIG. 5A, first, a support substrate 12 in which grooves and lands are formed only on one side is manufactured by a polycarbonate resin injection molding method using a metal stamper. By using an injection mold, the support substrate 12 is provided with recording conditions including address information, recording / reproducing power, etc. of the first recording / reproducing layer group 14 and the second recording / reproducing layer group 34, and the position of each recording / reproducing layer. Alternatively, basic information that should be held in advance when the medium is manufactured, such as the distance between layers, is preformatted. Specifically, basic information is preformed using the wobble of the land 20A or the groove 20B. The production of the support substrate 12 is not limited to the injection molding method, and may be produced by the 2P method or other methods.

  Thereafter, the second servo layer 20 is formed on the surface of the support substrate 12 on the side where the grooves and lands are provided. The second servo layer 20 is formed by a sputtering method or the like with a film that is reflective to the light source of the tracking optical system 200A (for example, a metal film such as Al or Ag).

  Next, as shown in FIG. 5B, the inter-servo buffer layer 19 is formed on the second servo layer 20 side of the support substrate 12 on which the second servo layer 20 is formed. At this time, grooves 18B and lands 18A are formed on the surface of the inter-servo buffer layer 19. Specifically, a viscosity-adjusted acrylic or epoxy UV curable resin is formed on both surfaces of the support substrate 12 by spin coating or the like, and the groove 18B is formed on the inter-servo buffer layer 19 side with a transparent resin stamper. And after forming land 18A, it is hardened by irradiating with ultraviolet rays. As a result, the inter-servo buffer layer 19 is formed. The inter-servo buffer layer 19 can also be formed on the surface of the second servo layer 20 by spraying, DIP method or the like instead of the ultraviolet curable resin.

  Thereafter, the first servo layer 18 is formed on the surface of the inter-servo buffer layer 19. Specifically, a film (for example, a metal thin film such as Al or Ag) having both reflectivity and transparency with respect to the light source of the tracking optical system 200A is formed on the surface of the inter-servo buffer layer 19 by a sputtering method or the like. Form.

  Next, as shown in FIG. 5C, the first buffer layer 17 and the second buffer layer 37 are simultaneously formed on the surface of the first servo layer 18 and the surface 30A of the support substrate 12 on the opposite side. For example, a viscosity-adjusted acrylic or epoxy ultraviolet curable resin is formed into a film on both surfaces of the support substrate 12 by a spin coat method or the like, and this is cured by irradiating ultraviolet rays to the first and second buffers. Layers 17 and 37 are formed. Instead of the ultraviolet curable resin, a light transmissive sheet made of a light transmissive resin is attached to both surfaces of the support substrate 12 using an adhesive, an adhesive, or the like, and the first and second buffer layers 17 and 37 are attached. It can also be. In addition, the first and second buffer layers 17 and 37 can be formed on both surfaces of the support substrate 12 by spraying, DIP method, or the like.

  Next, as shown in FIG. 5D, the L0 recording / reproducing layer 14A and the second recording / reproducing layer group 34 of the first recording / reproducing layer group 14 are respectively formed on the first buffer layer 17 and the second buffer layer 37. The L0 recording / reproducing layer 34A is simultaneously formed. Specifically, a dielectric film, a write-once recording film, and a dielectric film are formed in this order using a vapor phase growth method. Among these, it is preferable to use a sputtering method. Thereafter, the L0 intermediate layer 16A of the first intermediate layer group 16 is formed on the L0 recording / reproducing layer 14A of the first recording / reproducing layer group 14, and the L0 recording / reproducing layer 34A of the second recording / reproducing layer group 34 is formed. The L0 intermediate layer 36A of the second intermediate layer group 36 is formed. These formations are performed simultaneously. The L0 intermediate layers 16A and 34A are formed, for example, by forming a film of an ultraviolet curable resin whose viscosity has been adjusted by spin coating or the like, and then irradiating and curing the ultraviolet curable resin with ultraviolet rays. By repeating this procedure, the first recording / reproducing layer group 14 and the first intermediate layer group 16 are alternately stacked on the first buffer layer 17 side, and the second recording / reproducing layer group 34 on the second buffer layer 37 side. And the 2nd intermediate | middle layer group 36 is laminated | stacked alternately.

  When the formation of the L5 recording / reproducing layer 14F of the first recording / reproducing layer group 14 and the formation of the L5 recording / reproducing layer 34F of the second recording / reproducing layer group 34 are completed, as shown in FIG. The second cover layers 11 and 31 are simultaneously formed to complete the optical recording medium 10. The first and second cover layers 11 and 31 are formed by, for example, coating a viscosity-adjusted acrylic or epoxy UV curable resin by a spin coating method or the like, and irradiating the UV with respect to this to cure. To form. In addition, although the said manufacturing method was demonstrated in this embodiment, this invention is not specifically limited to the said manufacturing method, Another manufacturing technique can also be employ | adopted.

  Next, an optical recording / reproducing method for recording / reproducing information on / from the optical recording medium 10 using the optical recording / reproducing apparatus 70 of the present embodiment will be described with reference to FIGS. In the present embodiment, the first servo layer 18 is used to simultaneously record information in the first and second recording / reproducing layer groups, and the second servo layer 20 is used to record the first and second recording / reproducing layer groups. The process of simultaneously recording information is repeated alternately.

  First, preconditions for performing this optical recording / reproducing method will be described. As shown in FIG. 9, the optical recording medium 10 is disposed on the spindle S with the first surface 10A on the lower side and the second surface 30A on the upper side. When the spindle S is viewed from below, the optical recording medium 10 rotates clockwise. The first spiral direction of the land 18A and the groove 18B of the first servo layer 18 is such that when the optical recording medium 10 is viewed from the first surface 10A side, it spreads counterclockwise from the inner peripheral side to the outer peripheral side. Is set. On the other hand, the second spiral direction of the land 20A and the groove 20B of the second servo layer 20 is a direction spreading from the inner peripheral side to the outer peripheral side along the clockwise direction when the optical recording medium 10 is viewed from the first surface 10A side. That is, it is set in the direction opposite to the first spiral direction. Here, the case where recording or reproduction is performed on the first recording / reproducing layer group 14 using the first optical pickup 90A is referred to as first recording / reproducing operation, and second recording is performed using the second optical pickup 90B. A case where recording or reproduction is performed on the reproduction layer group 34 is referred to as a second recording / reproduction operation.

  <Simultaneous recording of information in the first and second recording / reproducing layer groups using the first servo layer>

  The input / output interface unit 87C in the digital signal processing device 86 receives data to be recorded from an external information device, and transmits the data to the division / synthesis processing unit 87C. In the division / combination processing unit 87C, the transmitted data to be recorded is divided into first data and second data and transmitted to the recording processing unit 87B. The recording processor 87B controls the recording power of the light source 101A of the first optical pickup 90A to record the first data on the first recording / reproducing layer group 14 (first recording / reproducing operation). At the same time, the recording processor 87B controls the recording power of the light source 101B of the second optical pickup 90B to record the second data on the second recording / reproducing layer group 34 (second recording / reproducing operation). The details of the first and second recording / reproducing operations are as follows.

  (First Recording / Reproducing Operation) As shown in FIGS. 6 and 9A, when recording information on the L0 recording / reproducing layer 14A of the first recording / reproducing layer group 14, the tracking optical of the first optical pickup 90A is recorded. Tracking is performed by irradiating the first servo layer 18 with a beam 270A in the red wavelength region of the system 200A from the first surface 10A. Specifically, tracking is performed by irradiating the spot of the beam 270A to the groove 18B and the land 18A in the first servo layer 18.

  Simultaneously with the tracking, the L0 recording / reproducing layer 14A is irradiated from the first surface 10A with the recording beam 170A in the blue wavelength region of the recording / reproducing optical system 100A of the first optical pickup 90A.

  As a result, the optical recording medium 10 rotating clockwise as viewed from the first surface 10A side moves from the inner periphery to the outer periphery along the grooves 18B and lands 18A, and information is transferred to the L0 recording / reproducing layer 14A. Is recorded. The track pitch P2 of the recording mark formed on the L0 recording / reproducing layer 14A is half of the pitch P1 between the groove 18B or the land 18A.

  (Second Recording / Reproducing Operation) When information is recorded on the L0 recording / reproducing layer 34A of the second recording / reproducing layer group 34, the second light is utilized by using the tracking error signal of the first optical pickup 90A in the first recording / reproducing operation. Tracking control of the pickup 90B is performed. As a result, the first optical pickup 90 </ b> A and the second optical pickup 90 </ b> B are opposite to each other in optical axis and are substantially coaxial. In this state, the L0 recording / reproducing layer 34A is irradiated with a recording beam 170B in the blue wavelength region of the recording / reproducing optical system 100B of the second optical pickup 90B.

  As a result, as shown in FIG. 9A, the grooves 18B and lands 18A of the first servo layer 18 are formed on the optical recording medium 10 that rotates counterclockwise as viewed from the second surface 30A side. The information is recorded on the L0 recording / reproducing layer 34A while moving from the inner periphery to the outer periphery. The track pitch P2 of recording marks formed on the L0 recording / reproducing layer 34A is also half of the pitch P1 between the grooves 18B or lands 18A of the first servo layer 18.

  By proceeding simultaneously with the first recording operation and the second recording operation, simultaneous recording of information on the first and second recording / reproducing layer groups 14 and 34 using the first servo layer 18 is realized.

  In the first servo layer 18, basic specifications relating to the optical recording medium 10 and information relating to the number of stacked first and second recording / reproducing layer groups 14 and 34 are recorded in advance in recording pits and BCA (burst cutting area). Has been. Accordingly, the beam 270A in the red wavelength region is always read out before the start of tracking control. The basic specifications relating to the optical recording medium 10 include rules regarding the positions of the first and second servo layers 18 and 20, the positions of the recording / reproducing layers, and the interlayer distance of the recording / reproducing layer group.

  After the necessary information has been recorded on the L0 recording / reproducing layer 14A of the first recording / reproducing layer group 14 and the L0 recording / reproducing layer 34A of the second recording / reproducing layer group 34, this additional recording information (related to recording) Address information, content information, etc.) are simultaneously recorded in a management area reserved in advance in a part of the L0 recording / reproducing layers 14A, 34A.

  Thereafter, when recording information on the L0 recording / reproducing layers 14A, 34A is resumed, first, the management area of the L0 recording / reproducing layers 14A, 34A is reproduced, the position where the previous recording is completed is confirmed, and the recording is started from that position. Continue. In this way, the recording operation is continued at the same time until information recording is completed for all of the data areas in the L0 recording / reproducing layers 14A and 34A.

  <Simultaneous recording of information to the first and second recording / reproducing layer groups using the second servo layer>

  When recording in the data area of the L0 recording / reproducing layers 14A, 34A is completed, as shown in FIGS. 7 and 9B, data in the L1 recording / reproducing layers 14B, 34B adjacent to the L0 recording / reproducing layers 14A, 34A is obtained. Start recording for the area.

  (First Recording / Reproducing Operation) When information is recorded on the L1 recording / reproducing layer 14B of the first recording / reproducing layer group 14, the beam 270A in the red wavelength region of the first optical pickup 90A is emitted from the first surface 10A to the second servo layer. 20 is tracked. Specifically, tracking is performed by irradiating the spot of the beam 270A to the groove 20B and the land 20A in the second servo layer 20.

  Simultaneously with the tracking, the L1 recording / reproducing layer 14B is irradiated from the first surface 10A with the recording beam 170A in the blue wavelength region of the recording / reproducing optical system 100A of the first optical pickup 90A.

  As a result, as viewed from the first surface 10A side, the optical recording medium 10 rotating in the clockwise direction (first rotation direction) moves from the outer periphery to the inner periphery along the groove 20B and the land 20A. Information is recorded on the recording / reproducing layer 14B. The track pitch P2 of the recording marks formed on the L1 recording / reproducing layer 14B is half of the pitch P1 between the groove 20B or the land 20A.

  (Second Recording / Reproducing Operation) When information is recorded on the L1 recording / reproducing layer 34B of the second recording / reproducing layer group 34, the second light is utilized by using the tracking error signal of the first optical pickup 90A in the first recording / reproducing operation. Tracking control of the pickup 90B is performed. Simultaneously with this tracking, the L1 recording / reproducing layer 34B is irradiated with the recording beam 170B in the blue wavelength region of the recording / reproducing optical system 100B of the second optical pickup 90B.

  As a result, when viewed from the second surface 30A side, the optical recording medium 10 that rotates counterclockwise (second rotation direction) from the outer periphery to the inner periphery along the groove 20B and the land 20A of the second servo layer 20 is obtained. The information is recorded on the L1 recording / reproducing layer 34B while moving to. The track pitch P2 of the recording marks formed on the L1 recording / reproducing layer 34B is also half of the pitch P1 between the groove 20B or the land 20A of the second servo layer 20.

  By simultaneously proceeding the first recording operation and the second recording operation described above, simultaneous recording of information on the first and second recording / reproducing layer groups 14 and 34 using the second servo layer 20 is realized.

  After the necessary information has been recorded on the L1 and L2 recording / reproducing layers 14B and 34B, the current additional recording information (address information, content information, etc. relating to recording) is stored in the L0 recording / reproducing layer 14A, It is recorded in the management area 34A.

  As a result of repeating the above recording operation, in the present optical recording / reproducing method, as indicated by an arrow Q in FIG. 7, the first servo layer 18 is used to move from the inner side to the outer side in the radial direction of the optical recording medium 10. Recording and recording from the outer side to the inner side in the radial direction of the optical recording medium 10 by using the second servo layer 20 are performed alternately.

  In the present embodiment, in the first and second recording / reproducing layer groups 14 and 34, information is simultaneously recorded on a pair of recording / reproducing layers having the same stacking order from the center side in the thickness direction. In particular, a pair of recording / reproducing layers are selected in the order of lamination from the center side in the thickness direction of the optical recording medium 10 to the outside, and information is recorded.

  Although the case where the management area is secured in the L0 recording / reproducing layers 14A and 34A is illustrated here, other recording / reproducing layers may be used as the management area. Further, when the first and second servo layers 18 and 20 are provided with a recording film, a management area is secured in the first and second servo layers 18 and 20 and additional information is recorded therein. preferable. For recording on the first and second servo layers 18 and 20, a beam 270A for tracking control may be used. By consolidating the management information in the first and second servo layers 18 and 20, it becomes possible to simultaneously grasp the management information of both the first recording / reproducing layer group 14 and the second recording / reproducing layer group 34.

  <Simultaneous reproduction of information in first and second recording / reproducing layer groups>

  When the digital signal processor 86 receives a reproduction request for data recorded on the optical recording medium 10 from an external information device, the reproduction processor 87A of the digital signal processor 86 uses the first and second optical pickups 90A. The information recorded on the optical recording medium 10 is reproduced by controlling the power of the 90B light sources 101A and 101B to a predetermined reproduction level. As already described in the recording operation, in the present embodiment, the data to be recorded is divided into the first data and the second data, and the same stacking order of the first and second recording / reproducing layer groups 14 and 34 is set. Since the data is recorded separately on the pair of recording / reproducing layers, the first data and the second data are reproduced at the same time during reproduction, and the reproduced data is restored by combining them.

  (First Recording / Reproducing Operation) As shown in FIG. 8, when reproducing the first data recorded in the L0 recording / reproducing layer 14A of the first recording / reproducing layer group 14, the recording / reproducing of the first optical pickup 90A is performed. The L0 recording / reproducing layer 14A is irradiated with the beam 170A of the optical system 100A for reproduction while performing tracking control and focus control.

  (Second Recording / Reproducing Operation) When reproducing the second data recorded in the L0 recording / reproducing layer 34A of the second recording / reproducing layer group 34, the beam 170B of the recording / reproducing optical system 100B of the second optical pickup 90B is used. The L0 recording / reproducing layer 34A is irradiated and reproduced while performing tracking control and focus control.

  By simultaneously proceeding with the first reproduction operation and the second reproduction operation, simultaneous reproduction of the first data and the second data in the first and second recording / reproduction layer groups 14 and 34 is realized. During recording, the first and second servo layers 18 and 20 are used for tracking control. However, during simultaneous reproduction, the recording and reproduction optical systems 100A and 100B are used to perform the first and second servo layers 18 and 20, respectively. Tracking control of each of the second optical pickups 90A and 90B is performed separately.

  The reproduction processor 87A receives the analog reproduction signals of the first and second optical pickups 90A and 90B, converts the analog signals into digital signals, and obtains first data and second data. Further, the reproduction processing unit 87A transfers the first and second data to the division / combination processing unit 87C. The division / combination processing unit 87C combines the first and second data received from the reproduction processing unit 87A into one reproduction data, and transmits this reproduction data to the input / output interface unit 87C. The input / output interface unit 87C outputs the reproduction data to an external information device.

  As described above, according to the optical recording / reproducing method of this embodiment, the first or second servo layer 18 or 20 is viewed from the first surface 10A side while performing tracking control by irradiating the tracking beam 270A. The first recording / reproducing layer group 14 that rotates clockwise is irradiated with a recording / reproducing beam 170A to record or reproduce information, and at the same time, it rotates counterclockwise as viewed from the second surface 30A side. The recording / reproducing beam 170B is irradiated to the second recording / reproducing layer group 34 to record or reproduce information. As a result, information can be recorded or reproduced simultaneously with respect to the pair of recording / reproducing layers, so that the information transfer rate can be greatly increased.

  Furthermore, in this optical recording / reproducing method, the recording / reproducing beam 170A of the first optical pickup 90A and the recording / reproducing beam of the second optical pickup 90B are shared by sharing either the first or second servo layer 18, 20. Information is simultaneously recorded on the pair of recording / reproducing layers while maintaining 170B substantially coaxial with each other. As a result, since the first data and the second data are always recorded at the same tracking position, it is possible to simplify the reproduction control when reproducing simultaneously. In the second optical pickup 90B in the optical recording / reproducing apparatus 70, the tracking optical system can be omitted, and the structure can be simplified.

  In the present embodiment, if a large amount of the tracking beam 270A applied to the second servo layer 20 passes through the second servo layer 20, it adversely affects the second optical pickup 90B arranged coaxially. Easy to give. Therefore, in the present optical recording medium 10, in the second servo layer 20, the transmittance of the tracking beam 270A is set to 10% or less, thereby suppressing the adverse effect of the beam 270A on the second optical pickup 90B side. .

  The digital signal processing device 86 of the optical recording / reproducing device 70 divides recording data received from an external information device into first data for the first recording operation and second data on the second recording operation side, Simultaneous recording is performed on a pair of recording / reproducing layers. Further, the digital signal processing device 86 reproduces the first data and the second data simultaneously recorded on the pair of recording / reproducing layers, and further synthesizes the first data and the second data, as if one Output to external information equipment as if it were playback data. Therefore, since it is possible to provide the same interface as that of the conventional optical recording / reproducing apparatus for recording or reproducing with respect to one recording / reproducing layer, it is possible to change the specifications of the external information device. It can be made unnecessary.

  Furthermore, in this optical recording / reproducing method, the optical recording medium 10 includes a first servo layer 18 having a tracking control unevenness or groove in the first spiral direction as a servo layer, and a second spiral opposite to the first spiral direction. A second servo layer 20 having an unevenness or groove for tracking control in the direction is provided. A step of simultaneously performing the first recording operation and the second recording operation while performing tracking control from the inner circumference side to the outer circumference side of the optical recording medium 10 using the first servo layer 18; The steps of performing the first recording operation and the second recording operation are alternately performed every time the recording / reproducing layer is switched while performing tracking control from the outer peripheral side to the inner peripheral side of the optical recording medium 10 in common. It is like that. Therefore, as shown in FIG. 7, when the recording / reproducing layer is switched, the recording / reproducing beams 170A and 170B of the first and second optical pickups 90A and 90B are simply moved in the focus direction, and a pair of movement destinations is obtained. It is possible to quickly move to the recording start position or the reproduction start position of the recording / reproducing layer. As a result, it is possible to suppress a decrease in transfer rate when the recording / reproducing layer is switched.

  In this optical recording / reproducing method, the wavelength of the tracking beam 270A and the wavelengths of the recording / reproducing beams 170A, 170B are set to be different from each other. In particular, the tracking beam 270A is set to 630 to 680 nm in red, and the wavelengths of the recording and reproducing beams 170A and 170B are set to 380 to 450 nm in blue.

  In addition to this, in this optical recording medium 10, the reflectance of the first and second servo layers 18 and 20 when the tracking red wavelength beam 270A is irradiated, the provision of the recording / reproducing beam 170A is the first. The reflectance is set larger than the reflectance when the second servo layers 18 and 20 are irradiated. In order to achieve this specifically, for the first buffer layer 17, a material is selected that has a greater light absorption as the beam wavelength is shorter.

  In this case, even if the recording / reproducing beam 170A having a blue wavelength is incident on the first and second servo layers 18 and 20, the first buffer layer 17 is likely to absorb the first and second beams. The amount of light reaching the servo layers 18 and 20 (the amount of reflected light from the first and second servo layers 18 and 20) can be suppressed. On the other hand, since the tracking beam 270A by the first optical pickup 90A can actively transmit through the first buffer layer 17, the amount of light reaching the first and second servo layers 18 and 20 (first and second servo layers). (Amount of reflected light from 18, 20) can be increased. As a result, it is possible to improve the quality of the reproduction signal and at the same time realize stable tracking control.

  In the present embodiment, the first buffer layer 17 is provided with a characteristic that the light absorption rate differs between the tracking beam (red wavelength) and the recording / reproducing beam (blue wavelength). Although the reflectance of the second servo layers 18 and 20 is different between the tracking beam and the recording / reproducing beam, the present invention is not limited to this. For example, the wavelength dependent characteristics such that the reflectance varies depending on the wavelength may be imparted to the reflective films themselves formed on the first and second servo layers 18 and 20. In addition to the first buffer layer 17, a filter layer having wavelength dependency characteristics of light transmittance and absorption rate may be separately formed.

  Also, according to this optical recording / reproducing method, information is recorded using two independent recording / reproducing beams 170A and 170B. Accordingly, it is possible to share the focal movement range of the recording / reproducing beams 170A and 170B of the first and second optical pickups 90A and 90B in the thickness direction. As a result, even if the number of recording / reproducing layers is increased, it is possible to obtain an advantageous state with respect to coma aberration such as tilt.

  Specifically, in the present optical recording / reproducing method, the first optical pickup 90A performing the first recording operation performs recording on the first recording / reproducing layer 14 disposed on the first surface 10A side of the optical recording medium 10, In the second optical pickup 90B performing the second recording operation, recording is performed on the second recording / reproducing layer 34 disposed on the second surface 30A side of the optical recording medium 10. As a result, the optical recording medium 10 can bring the first recording / reproducing layer 14 closer to the first surface 10A and the second recording / reproducing layer group 34 closer to the second surface 30A. As a result, the number of recording / reproducing layers is increased, and this is further advantageous for coma in tilt and the like.

  Further, the first recording / reproducing layer group 14 and the second recording / reproducing layer group 34 of the optical recording medium 10 used in the present embodiment are the same in positions symmetrical with respect to the center in the thickness direction of the optical recording medium 10. Has been placed. In this way, the optical design of the first and second optical pickups 90A and 90B of the optical recording / reproducing apparatus 70, the position recognition of the recording / reproducing layer, the focus control, etc. can be shared, and the recording / reproducing speed can be increased. . In addition, since the internal stress generated in the first and second recording / reproducing layer groups 14 and 34 in the optical recording medium 10 is also symmetric in the thickness direction, the warp of the optical recording medium 10 is also suppressed. For example, even if the thickness of the support substrate 12 is set within a range of 100 μm to 1000 μm, the warp of the optical recording medium 10 can be suppressed.

  Further, in the present optical recording / reproducing method, with respect to the first recording / reproducing layer group 14 and the second recording / reproducing layer group 34, with respect to the recording / reproducing layers having the same stacking order from the center in the thickness direction of the optical recording medium 10. Information is recorded at the same time. In this way, for the pair of recording / reproducing layers to be recorded, the distances from the surfaces 10A and 30A of the optical recording medium 10 are close to each other, and the optical path of the beam is also symmetric. As a result, for example, the control signal obtained in the first optical pickup 90A, specifically, the control information such as the tilt and the surface shake of the optical recording medium 10, can be directly used in the second optical pickup 90B if the polarity of the information is reversed. Can be used as a control signal. As a result, in the second optical pickup 90B, it is possible to omit a photodiode mechanism or the like specially for obtaining this control signal.

  Further, in this optical recording medium 10, the thicknesses of the first buffer layer 17 and the second buffer layer 37 that are relatively thick are approximated, and the first and second buffer layers 17 and 37 are formed simultaneously. Thus, warping of the support substrate 12 can be suppressed. This means that the support substrate 12 can be made thin or made of a material having low rigidity, and the space for forming the recording / reproducing layer can be increased accordingly.

  In particular, in the present embodiment, when the optical recording medium 10 is manufactured, the first buffer layer 17 and the second buffer layer 37, the first recording / reproducing layer group 14, and the second recording / reproducing layer are excluded except for the inter-servo buffer layer 19. The group 34, the first intermediate layer group 16 and the second intermediate layer group 36 are formed simultaneously on both sides. As a result, the internal stress generated during UV curing acts equally on both sides of the support substrate 12, so that the warp of the optical recording medium 10 can be further reduced.

  In the optical recording / reproducing method of the above embodiment, information is recorded in the first and second recording / reproducing layer groups 14 and 34 in the order of lamination from the center side in the thickness direction of the optical recording medium 10 to the outside. Although illustrated, this invention is not limited to this. For example, in the first and second recording / reproducing layer groups 14 and 34, it is possible to record information in the order of lamination from the outer side of the optical recording medium 10 toward the center side. Further, a pair of recording / reproducing layers having the same stacking order may be randomly extracted from the first and second recording / reproducing layer groups 14 and 34 and recorded.

  Furthermore, in the optical recording / reproducing method of the above embodiment, the case where information is recorded or reproduced on a pair of recording / reproducing layers having the same stacking order from the center side in the thickness direction of the optical recording medium 10 is illustrated. The invention is not limited to this. For example, as indicated by an arrow Q in FIG. 10, the stacking order from the first surface 10A side of the first recording / reproducing layer group 14 in the first recording / reproducing operation, and the second recording / reproducing layer group 34 in the second recording / reproducing operation. It is also possible to select a pair of recording / reproducing layers having the same stacking order from the center in the thickness direction of the optical recording medium 10.

  In this way, the focal distance T between the focal point of the recording / reproducing beam 170A on the first optical pickup 90A side and the focal point of the recording / reproducing beam 170B on the second optical pickup 90B side is constant or relatively stable. Can be made. As a result, the number of intermediate layer groups 16 and 36 existing between the focal points of the pair of beams 170A and 170B is always constant. Accordingly, it is possible to keep the fluctuation amount of the focal distance T due to the film formation error of the intermediate layer groups 16 and 36 within a certain range, thereby reducing the focus error and the like. In particular, when the beams 170A and 170B jump to the next recording / reproducing layer, if the focal points of the beams 170A and 170B are simultaneously moved in a state where the focal distance T is fixed, the beam 170A and 170B jumps to the wrong recording / reproducing layer. Probability can be reduced.

  In the optical recording medium 10 of the above embodiment, the case where the thicknesses of the first cover layer 11 and the second cover layer 31 are the same is illustrated, but the present invention is not limited to this. For example, it is also preferable that the thicknesses of the first cover layer 11 and the second cover layer 31 are made different as in the optical recording medium 10 shown in FIG. Specifically, the thickness of the first cover layer 11 is set to be larger by the thickness of the support substrate 12 than the thickness of the second cover layer 31. By doing so, the first and second servo layers 18 and 20 are arranged at the center of the optical recording medium 10 in the thickness direction. Note that when the optical recording medium 10 is manufactured, the first cover layer 11 and the second cover layer 31 having different thicknesses are preferably laminated separately. Even if these layers are not laminated at the same time, the support substrate 12, the first and second buffer layers 17, 37, the first recording / reproducing layer group 14, the first intermediate layer group 16, the second recording / reproducing layer group 34, and the second Since the intermediate layer group 36 has already secured a certain degree of rigidity, warping and deformation of the optical recording medium 10 are sufficiently suppressed.

  Further, as in the optical recording medium 10 shown in FIG. 12, the thicknesses of the first and second buffer layers 17 and 37 are changed, and the interlayer distance and the number of layers of the first and second recording / reproducing layer groups 14 and 34 are changed. As a result, it is possible to position the first and second servo layers 18 and 20 at the center in the thickness direction.

  Further, in the above embodiment, the recording and reproducing layers of the first and second recording and reproducing layer groups 14 and 34 are shown only when the recording film is formed in advance, but the present invention is not limited to this. For example, like the optical recording medium 10 shown in FIG. 13, the first and second bulk layers 13 and 33 having a predetermined thickness are formed as a whole where the first and second recording / reproducing layer groups can be in the future. Can do. When the first and second bulk layers 13 and 33 are irradiated with the recording beams 170A and 170B, only the focal portion of the beam spot undergoes a state change to form a recording mark. That is, the optical recording medium in the present invention is not limited to the recording / reproducing layer on which the beam is irradiated, but a recording mark is formed in the planar area as needed. This includes the case where the two recording / reproducing layer groups 14 and 34 are formed in a multi-layer structure. By adopting the structure of the bulk layers 13 and 33 in the optical recording medium 10, the position of the recording / reproducing layer can be freely set within the range of the bulk layers 13 and 33. For example, even if the thickness and arrangement of the first bulk layer 13 and the second bulk layer 33 are different from each other, the distances from the first and second surfaces 10A and 30A of the first and second recording / reproducing layer groups 14 and 34 are different. , Can be matched to each other. Here, a structure in which the cover layer and the buffer layer are omitted when the first and second bulk layers 13 and 33 are employed is illustrated.

  Further, in the optical recording medium 10 to which the optical recording / reproducing method of this embodiment is applied, both the first and second servo layers 18 and 20 are formed on one side of the support substrate 12, and both sides of the support substrate 12 are formed. Although the case where the first recording / reproducing layer group 14 and the second recording / reproducing layer group 34 are arranged is shown, the present invention is not limited to this. For example, as shown in FIG. 14, the first servo layer 18 may be disposed on one side of the support substrate 12 and the second servo layer 20 may be disposed on the other side. Since the symmetry in the thickness direction of the optical recording medium 10 is further improved, warping can be reduced.

  In the present embodiment, the case where the wavelength of the tracking beam 270A and the wavelengths of the recording / reproducing beams 170A and 170B are different between red and blue is shown. However, the present invention is not limited to this, You may employ | adopt the beam of the same wavelength range between recording / reproducing.

  The optical recording medium and the like of the present invention can be applied to various optical recording media having a servo layer and a recording / reproducing layer.

DESCRIPTION OF SYMBOLS 10 Optical recording medium 11 1st cover layer 12 Support substrate 14 1st recording / reproducing layer group 16 1st intermediate | middle layer group 17 1st buffer layer 18 1st servo layer 19 Inter-servo buffer layer 20 2nd servo layer 31 2nd cover layer 34 Second recording / reproducing layer group 36 Second intermediate layer group 37 Second buffer layer 90A First optical pickup 90B Second optical pickup

Claims (11)

Servo layers having irregularities or grooves for tracking control, and a plurality of first recording / reproducing layers which are previously laminated on the first surface side with respect to the servo layer or formed afterwards and have no irregularities for tracking control, Recording information on an optical recording medium having a plurality of second recording / reproducing layers that are previously laminated on the second surface side with respect to the servo layer or formed afterwards and have no unevenness for tracking control An optical recording / reproducing method for reproducing,
By irradiating the first recording / reproducing layer from the first surface to the first recording / reproducing layer while performing tracking control by irradiating the servo layer with the tracking beam, the servo layer is viewed from the first surface side. A first recording operation for recording information in the first rotation direction;
A second recording / reproducing beam that is executed simultaneously with the first recording operation and performs tracking control using the servo layer that is common to the first recording operation, from the second surface to the second recording / reproducing layer. A second recording operation for recording information in a second rotation direction opposite to the first rotation direction as viewed from the second surface side,
An optical recording / reproducing method for an optical recording medium, comprising: The first recording operation and the second recording operation are performed simultaneously while maintaining the first recording / reproducing beam and the second recording / reproducing beam in a substantially coaxial state.
The optical recording / reproducing method of the optical recording medium according to claim 1. Irradiating the servo layer with the common tracking beam, and simultaneously executing the first recording operation and the second recording operation,
An optical recording / reproducing method for an optical recording medium according to claim 1 or 2. Data to be recorded on the optical recording medium by the digital signal processing device that controls the first and second recording / reproducing beams is divided into first data on the first recording operation side and second data on the second recording operation side. It is divided into data,
4. An optical recording / reproducing method for an optical recording medium according to claim 1. The optical recording medium is the servo layer,
A first servo layer having the tracking control irregularities or grooves in the first spiral direction; and a second servo layer having the tracking control irregularities or grooves in the second spiral direction opposite to the first spiral direction; So that
Performing the first recording operation and the second recording operation while performing tracking control from the inner circumference side to the outer circumference side of the optical recording medium using the common first servo layer;
And performing the first recording operation and the second recording operation while performing tracking control from the outer peripheral side to the inner peripheral side of the optical recording medium using the common second servo layer. Characterized by the
5. An optical recording / reproducing method for an optical recording medium according to claim 1. The wavelength of the tracking beam and the wavelength of the first or second recording / reproducing beam are different from each other,
An optical recording / reproducing method for an optical recording medium according to claim 1. The wavelength of the first or second recording / reproducing beam is in a range of 380 to 450 nm,
An optical recording / reproducing method for an optical recording medium according to claim 1. A first servo layer having the tracking control irregularities or grooves in a first spiral direction;
A second servo layer having the unevenness or groove for tracking control in a second spiral direction opposite to the first spiral direction;
A plurality of first recording / reproducing layers which are previously laminated on the first surface side with respect to the first and second servo layers or are formed afterwards, and have no unevenness for tracking control;
A plurality of second recording / reproducing layers that are pre-laminated on the second surface side with respect to the first and second servo layers or formed afterwards, and do not have irregularities for tracking control;
An optical recording medium comprising: Servo layers having irregularities or grooves for tracking control, and a plurality of first recording / reproducing layers which are previously laminated on the first surface side with respect to the servo layer or formed afterwards and have no irregularities for tracking control, Recording information on an optical recording medium having a plurality of second recording / reproducing layers that are previously laminated on the second surface side with respect to the servo layer or formed afterwards and have no unevenness for tracking control A recording / reproducing apparatus for reproducing,
A tracking optical system for irradiating the servo layer with a tracking beam;
While performing tracking control using the tracking optical system, the first recording / reproducing beam is irradiated from the first surface to the first recording / reproducing layer, and the first rotation is viewed from the first surface side. A first recording / reproducing optical system for recording information in a direction;
Recording is performed simultaneously with the first recording / reproducing optical system, tracking control is performed using the tracking optical system, and second recording is performed from the second surface to the second recording / reproducing layer. A second recording / reproducing optical system that irradiates a reproducing beam and records information in a second rotation direction opposite to the first rotation direction when viewed from the second surface side;
An optical recording / reproducing apparatus for an optical recording medium, comprising: A first linear motion mechanism that moves both the first recording / reproducing optical system and the tracking optical system in a tracking direction;
A second linear motion mechanism for moving the second recording / reproducing optical system in the tracking direction,
The second linear motion mechanism is controlled using the tracking signal in the tracking optical system,
An optical recording / reproducing apparatus for an optical recording medium according to claim 9. Data to be recorded on the optical recording medium is recorded on the first recording / reproducing layer by the first recording / reproducing optical system, and on the second recording / reproducing layer by the second recording / reproducing optical system. A digital signal processing device that divides the second data into
11. An optical recording / reproducing apparatus for an optical recording medium according to claim 9 or 10.

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