JP2006107668A - Device and method for recording/reproducing information, and 3-dimensional recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for recording/reproducing information, having sure servo characteristics, and capable of high-speed random accessing, additional recording, and achieving a 3-dimensional high density recording, and a 3-dimensional recording medium. <P>SOLUTION: An interlayer movement to another recording layer is executed only in a predesignated area during recording/reproducing while applying beams emitted from a recording/reproducing light source 1 and a servo light source 16 to a 3-dimensional recording medium 8 provided with a servo layer 31 indicating positional information or the like beforehand and capable of recording data in a depth direction. The focal position movement of a recording/reproducing beam is carried out only by the lens movement of the recording medium side of a relay lens 5, and a spherical aberration accompanying the interlayer movement is corrected by a liquid crystal element 7. A recording mark is formed in the recording track of a radial direction adjacent to each recording mark by shifting only an interlayer half in a depth direction. Thus, a recording track pitch in the radial direction is narrowed, thereby achieving a high density. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information recording / reproducing apparatus, a recording / reproducing method, and an information recording medium, and more particularly, to record information that is continuously or randomly recorded and reproduced by three-dimensionally forming recording marks in the thickness direction of the recording medium. The present invention relates to a reproducing apparatus, a recording / reproducing method, and a three-dimensional recording medium on which three-dimensional recording marks are formed.

  In recent years, with the increase in information capacity, high-density recording technology using optical recording has been actively developed. In optical recording, the limit is said to be about 500 nm due to light diffraction. This diffraction limit is proportional to the wavelength of light, and further inversely proportional to the figure of merit (NA) of the lens.

  For this reason, one direction of increasing the density is to shorten the wavelength of light and to increase the NA of the aperture lens. Another method is to use an optical phenomenon that does not depend on the diffraction limit. As a recording medium, there is a method of forming a super-resolution film on the recording film. In the optical head, recently, a near field in light has attracted attention as a method for promoting these. For example, a high NA is realized using SIL (Solid Immersion Lens), and a spot diameter smaller than that using a normal optical lens is obtained.

  As described above, a method for further increasing the capacity by recording in the depth direction of the recording medium is considered in addition to the direction of reducing the beam spot for recording. One of them is to perform three-dimensional recording / reproduction on a recording medium in a bulk state as described in Patent Document 1.

  Various methods for recording and reproducing such a bulk state are conceivable. Among them, spiral recording as performed in the prior art has a great merit in that recording and reproduction can be performed continuously without waste. That is, the recording marks are sequentially formed on the spiral trajectory by rotating the optical disk and moving the light beam in the depth direction while scanning the optical beam in the radial direction of the optical disk. At this time, the recording mark can also be formed on the tree-annular locus by fixing the light beam at a predetermined position in the radial direction of the rotating optical disk and moving the light beam in the depth direction.

JP 2000-228014 A

  As in the prior art, in spiral recording and tree-ring recording, the recording marks are recorded while being shifted slightly in the depth direction, so they are recorded continuously for reliable servo and recording / reproduction. The relative positional relationship between the two recording marks is important. According to the prior art, the difference d between the distance L on the locus of the recording mark to be recorded and the relative position in the depth direction of the recording mark satisfies the relationship “0 <d / L <2.5”. .

  However, there is a case where the recording mark is greatly shifted in the depth direction of the recording mark due to a thermal influence during recording, and at that time, there is a possibility that the allowable range is not reached. Furthermore, there is a possibility that the recording mark spacing increases depending on the recording modulation method, and servo such as AF (auto focus) and tracking is not applied. Further, since the depth continuously changes, it is necessary to continually correct spherical aberration, and focus control is difficult.

  Further, as an example of the prior art, when reproduction of the same planar area is completed and the movement to the next layer is performed, the recording marks are arranged in a spiral manner at the connecting portion between the layers (from the innermost periphery to the outermost periphery). Then, since the moving distance between the recording marks and in the layer direction cannot be made so large, it takes a considerable time to move between the layers. Furthermore, the distance between the layers must be increased.

  In the prior art, the formation of recording marks in the depth direction can be performed by mechanical control of the recording apparatus. However, since there is no information in the depth direction in such spiral recording, recording once written is performed. It is difficult to perform high-speed playback and additional recording of marks. Even if information such as an address is written on the recording track, the target address cannot be reached unless it is continuously reproduced, and high-speed access is impossible. Of course, a reproduction method by mechanically controlling the depth direction is also conceivable, but the error of the depth position is large due to the difference between apparatuses and so on, which is not practical.

  The present invention solves such problems in the prior art, and provides an information recording / reproducing method capable of high-speed random access and additional recording with reliable servo characteristics and high density in three-dimensional recording. And a recording / reproducing apparatus and an information recording medium.

In order to solve this problem, the recording / reproducing apparatus of the present invention has the following features.
(1) Information that records information on this recording medium using a three-dimensional recording medium that has a servo layer having projections and depressions for representing information such as addresses and radial positions in advance and that can record data in the depth direction. The recording / reproducing apparatus comprises at least a servo light source for irradiating the servo layer with a beam and a recording / reproducing light source for irradiating the recording layer in the recording medium with a focal point of each beam emitted from each light source. Position control is possible separately, and during recording or reproduction of information by the recording / reproducing beam, recording marks in the depth direction in the recording medium are formed on other recording layers to be formed or to be formed. It is characterized in that it is executed only in an area provided for carrying out interlayer movement.

  Here, for convenience, an area provided for performing interlayer movement to another recording layer is referred to as an “interlayer switching area”.

  Here, the recording layer includes a virtual layer that is substantially parallel (coplanar) to the servo layer with a certain distance from the depth direction of the recording medium. That is, a recording film, a protective film, or the like is not formed as a recording layer in advance, and the recorded marks are arranged so that there is another layer on the same plane. Further, when recording is to be performed from now on, recording on the same plane as the virtual recording layer is performed.

  The servo layer has concavity and convexity grooves formed concentrically or spirally. A metal film or the like may be formed on the uneven surface as necessary.

  During recording or reproduction of information by the recording / reproducing beam, interlayer movement to another recording layer separated by a distance between recording marks in the depth direction is performed in the “interlayer switching region” while the recording medium rotates once. It is characterized by executing.

  Further, if the interlayer movement to another recording layer that is separated by the distance between the recording marks in the depth direction is performed every time the recording medium rotates, recording and reproduction in the depth direction can be continuously performed. . For example, recording / reproducing is started from a specific place in the first recording layer at a certain radius, and the recording / reproducing beam is transmitted to the next third recording layer while the recording medium makes one rotation. ”, And in the next rotation, the third layer moves from the third layer to the fifth layer through the“ interlayer switching region ”. Here, the reason for moving to the third layer without moving from the first layer to the second layer is that, as will be described later, the recording mark of the recording track adjacent in the radial direction is shifted in the depth direction with respect to each recording mark. Since recording is performed, when viewed at the same radius, the recording layer moves in every two layers in the depth direction (distance between recording marks). In this case, when the amount of information to be recorded / reproduced is small, the recording / reproduction is mainly moved in the depth direction, and the moving distance in the radial direction is reduced. For example, access to the recording start location at the time of additional recording Save time. The “interlayer switching region” here is formed in the depth direction ((number of recording layers / 2) −1) at the same radius.

  One feature of the present invention is that layer information is recorded or reproduced for each interlayer movement area in the “interlayer switching area” when moving to another recording layer separated by a distance between recording marks in the depth direction. It is. The layer information here may be expressed by wobbling a DC (continuous) mark or a mark row. That is, position information in the radial direction is controlled by the servo layer, and position control in the depth direction is performed by reading this layer information. As a result, high-speed access is possible during information reproduction. At this time, an AF pull-in part and an interlayer switching part by DC (continuous) marks are provided simultaneously with the layer information. This AF pull-in section is provided with this DC (continuous) mark to facilitate the pull-in of AF because it is difficult to pull in the AF in the recording mark row of information when random access is made. Similarly, an interlayer switching unit is provided to ensure AF during interlayer movement. From this point of view, it is preferable to make the width of these DC (continuous) marks wider than the width of the recording marks. User data is not recorded in this “interlayer switching area”. As an actual operation, the recording / reproducing beam is first moved from the servo layer side to the recording layer side, thereby detecting the reproduction signal of the AF pull-in portion by the DC (continuous) mark formed between the recording layers. When the number of reproduction signals of the AF pull-in unit is counted and the layer comes before the target layer, AF control is performed in the AF pull-in unit, and the layer information can be read immediately to enable reliable interlayer movement. . Based on the layer information, recording / reproduction is performed on the next recording layer through the interlayer switching unit.

  In addition, in order to improve random accessibility during information reproduction, an “interlayer switching region” that performs interlayer movement to another recording layer that is separated by a distance between recording marks in the depth direction is formed at the same radius. You may make it not overlap in the direction. That is, the area corresponding to each recording layer is shifted in the circumferential direction of the recording track. As an actual operation, the recording / reproducing beam is first moved from the servo layer side to the recording layer side, thereby detecting the reproduction signal of the AF pull-in portion by the DC (continuous) mark formed between the recording layers. The position in the circumferential direction where the reproduction signal of the AF pull-in portion is detected corresponds to the position (address, etc.) in the circumferential direction on the servo layer which is known in advance, so that the position in the depth direction is immediately known. . When the target layer comes before the target layer, AF control is performed by the AF pull-in unit, and the layer information can be read immediately to enable reliable interlayer movement. Based on the layer information, recording / reproduction is performed on the next recording layer through the interlayer switching unit. Note that once the relationship between the distance between the recording layers and the moving distance of the focal position of the recording / reproducing beam is examined, high-speed access is possible unless the recording medium is removed from the recording / reproducing apparatus.

  When performing additional recording, it is necessary to search again for the last position recorded before or to store it in the recording layer or in the internal memory of the recording / reproducing apparatus. However, as described above, an “interlayer switching area” for performing interlayer movement to another recording layer that is separated by the distance between the recording marks in the depth direction should be provided so as not to overlap in the depth direction at the same radius. You can quickly find the last position you recorded earlier.

  Further, the present invention is characterized in that it is executed only in an area provided for performing a movement to an adjacent recording track in the radial direction in a recording medium during recording or reproduction of information by a recording / reproducing beam.

  Here, for convenience, an area provided for performing the movement to the adjacent recording track is referred to as a “recording track switching area”. This “recording track switching area” often serves as the same area as the “interlayer switching area”.

  The movement to the adjacent recording track in the radial direction is simultaneously performed when moving between the lowermost layer or the uppermost layer of the recording layer in the recording medium. For example, at the time of reproducing information as well, when moving to the uppermost layer of the recording layer formed on the recording medium, a beam is irradiated in the radial direction along the DC (continuous) mark formed in the “recording track switching area”. Move the recording track. Since the recording track is provided for the unevenness provided in advance in the servo layer, the objective lens is moved in the radial direction by changing the polarity of the tracking servo in the servo beam, for example, from the convex part to the concave part of the servo layer. I will let you. The tracking servo in the “recording track switching area” at this time may be controlled by a recording / reproducing beam. At this time, when moving to the adjacent recording track in the radial direction, the recording head moves by about half the distance between the recording marks in the depth direction. By doing so, it shifts from the adjacent recording mark in the depth direction, and the recording density can be increased.

  In addition, when a recording medium that has never been recorded is set in the apparatus, it is possible to reduce the influence of recorded recording marks by sequentially recording from the recording layer close to the servo layer. It is preferable.

  In some cases, a buffer memory for the total scanning time of the “interlayer switching area” and the “recording track switching area” may be provided in the recording apparatus.

  Furthermore, in order to reliably and quickly form a recording mark, it is preferable to perform recording and reproduction simultaneously using a plurality of beams because recording and reproduction can be completed in a short time.

(2) An information recording / reproducing apparatus for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information in advance and is capable of recording data in the depth direction, A servo light source for irradiating the servo layer with a beam and a recording / reproducing light source for irradiating the recording layer in the recording medium with a beam, and control of the focal position of each beam emitted from each light source is possible. Beam position variable means in the depth direction for aligning the beam emitted from the recording / reproducing light source to at least the target recording layer, and the relationship between the moving distance of the focal position and the amount of spherical aberration is obtained in advance. An aberration correction mechanism is provided that automatically corrects the aberration according to the distance that the focal position of the beam emitted from the light source moves in the direction of the recording layer from the servo layer surface.

  In the present invention, in order to enable reliable servo and access, a servo layer is provided and AF control and tracking control are performed by a dedicated servo beam. In addition to this, reliable recording and reproduction are performed using a recording and reproduction beam. In this case, since the two beams use the same objective lens, the two beams cannot be controlled simultaneously by one objective lens. Therefore, the objective lens is controlled only by the servo beam. That is, the vertical shake and eccentricity generated during the rotation of the recording medium are controlled by the servo beam, and the objective lens is not controlled by the recording / reproducing beam. Here, the optical axes of the servo beam and the recording / reproducing beam with respect to the objective lens are the same. In the recording / reproducing apparatus of the present invention, the focal position of the servo beam and the focal position of the recording / reproducing beam can be arbitrarily changed. In the present invention, in the initial state, the focal position of the recording / reproducing beam is made farther than the focal position of the servo beam with respect to the objective lens. Actually, a relay lens is used to vary the focal position of the recording / reproducing beam in the depth direction. Further, by moving only the lens on the recording medium side of the relay lens, the focus position of the recording / reproducing beam can be reliably controlled without any change in the position where the parallel light is focused in the relay lens. In addition, by installing a pinhole at the focal point in the relay lens, the reflected beam other than the reflected beam from the target recording mark in the recording medium can be removed by this pinhole, and a reliable reproduction signal can be obtained. Can be obtained. Strictly speaking, it is preferable to automatically adjust the focal position of the recording / reproducing beam in accordance with the movement of the objective lens.

Usually, spherical aberration occurs depending on the thickness of a layer (a substrate, a protective layer, etc.) through which a recording / reproducing beam is transmitted. This spherical aberration is proportional to NA ⁴ × d / λ, where d is the thickness of the layer and λ is the wavelength of the beam. That is, it is necessary to correct spherical aberration by the thickness of this layer. Therefore, in the present invention, a liquid crystal element is used to correct spherical aberration. Since this liquid crystal element has anisotropy in the dielectric constant and the refractive index, the refractive index changes depending on the voltage applied to the liquid crystal element. By utilizing this physical property, spherical aberration is corrected.

Next, a method for automatically correcting spherical aberration will be described.
In the recording medium set in the recording / reproducing apparatus for the first time, each AF control means executes so that both the servo beam and the recording / reproducing beam are focused on the servo layer at the initially set radius. The parameter values (relay lens position, focus servo gain, etc.) at that time are stored in a memory in the apparatus. An area for acquiring these parameters may be provided at a radial position different from the recording / reproduction area (initial adjustment area).

  Further, the relationship between the moving distance of the focal position of the recording / reproducing beam and the amount of spherical aberration is stored in advance in an internal memory in the recording / reproducing apparatus.

  The beam emitted from the recording / reproducing light source moves in the direction of the recording layer with reference to the lens position on the recording medium side of the relay lens in a state where both the servo beam and the recording / reproducing beam are focused on the servo layer. When moved, the aberration correction amount is controlled by changing the lens position on the recording layer side. For example, when the recording / reproducing beam is focused on the third recording layer, about 20 μm from the lens position (reference position) on the recording medium side of the relay lens with the servo layer surface in focus. Assuming that the lens has moved, correction is performed by applying a voltage to the liquid crystal element by the correction amount when the lens is shifted by 20 μm based on the voltage correction distribution data stored in the internal memory (here, the layer thickness is known to some extent). If). In the present invention, correction data when 13 μm is shifted from the reference position by 5 μm is stored (13 data). If the layer thickness is several hundreds of micrometers, there is no problem in reproduction quality if aberration correction is performed even if it is deviated by about 5 micrometers, and the lens movement amount on the recording medium side is rounded off. This spherical aberration correction is preferably performed in the “interlayer switching region” or “recording track switching region”.

  Further, the optimum aberration correction amount corresponding to the moving amount of the focal position of the recording / reproducing beam is obtained again from the state where the two beams are focused on the servo layer, and recording / reproducing in the recording medium is performed based on the calculated value. Aberration correction may be automatically performed according to the distance moved from the reference position of the beam. In this case, spherical aberration can be corrected more reliably.

(3) An information recording / reproducing apparatus for recording information on the recording medium using a three-dimensional recording medium that has a servo layer indicating position information in advance and is capable of recording data in the depth direction. A servo light source for irradiating the servo layer with a beam and a recording / reproducing light source for irradiating the recording layer in the recording medium with a beam, and control of the focal position of each beam emitted from each light source is possible. The recording by the recording / reproducing beam emitted from the recording / reproducing light source is characterized in that the recording mark of the recording track adjacent to the radial direction is shifted in the depth direction with respect to each recording mark.

  Recording is performed at the highest density in three-dimensional recording by performing recording by shifting the recording mark of the recording track adjacent in the radial direction to each recording mark by about half of the distance between the recording marks in the depth direction. it can. That is, a high density of about 13.4% can be achieved in the radial direction.

  The servo layer is formed of a convex portion and a concave portion, and corresponds to the concave portion of the servo layer with respect to the distance between the recording mark closest to the servo layer corresponding to the convex portion of the servo layer and the convex portion of the servo layer. If recording is performed such that the distance between the recording mark closest to the servo layer and the concave portion of the servo layer is larger, the efficiency is further improved.

  As described above, by providing the “interlayer switching area” and “recording track switching area”, high-speed random access, which has been a problem in the past, has become possible, and the time required for interlayer switching can be greatly reduced. . In addition, the focal position of the recording / reproducing beam is moved only by moving the lens on the recording medium side of the relay lens, and the spherical aberration accompanying the interlayer movement is automatically corrected by the liquid crystal element, so that reliable recording / reproducing can be performed. It was. Furthermore, the recording track pitch in the radial direction can be reduced by forming the recording mark by shifting the recording track adjacent to each recording mark in the radial direction by half of the interlayer in the depth direction. It has become possible.

  Thus, according to the present invention, there are provided an information recording / reproducing apparatus, a recording / reproducing method, and an information recording medium capable of further increasing the density.

  The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the drawings.

(Example)
FIG. 1 is a diagram for explaining a recording / reproducing apparatus for a three-dimensional recording medium to which the present embodiment is applied. The recording / reproducing apparatus 100 includes a recording / reproducing high-power semiconductor laser 1 that emits laser light having a wavelength of 405 nm, a collimating lens 2 that collimates a beam from the recording / reproducing high-power semiconductor laser 1, and a polarization beam splitter 3. The λ / 4 plate 4, the relay lens 5 for changing the focal position of the recording / reproducing beam, the pinhole 6 provided in the relay lens 5 for increasing the SN of the reproduction signal, and the spherical surface for correcting the spherical aberration. An aberration correction plate (liquid crystal element) 7, an objective lens 9 for focusing the recording / reproducing beam and servo beam in the three-dimensional recording medium 8, and a signal reproducing and AF based on the beam returned from the recording medium And a beam splitter 10 that divides the beam into tracking beams, a narrowing lens 11 that narrows down the parallel rays for signals divided by the beam splitter 10, And can 12, and a detector 15, a narrowing lens 13 and cylindrical lens 14 to narrow the beam for the AF and tracking.

  In addition, the recording apparatus 100 includes a servo semiconductor laser 16 that emits a laser beam having a wavelength of 650 nm used for a servo beam, a collimator lens 17, a polarization beam splitter 18, a λ / 4 wavelength plate 19, and a wavelength of 405 nm. It has a dichroic mirror 20 that selectively transmits laser light and selectively reflects laser light having a wavelength of 650 nm, a reflection mirror 21, a focusing lens 22, a cylindrical lens 23, and a detector 24 for AF control. .

  Further, the recording apparatus 100 uses the laser driver 25 for controlling the recording / reproducing high-power semiconductor laser 1, the laser driver 26 for controlling the servo semiconductor laser 16, and the signal from the detector 24 to focus the objective lens 9. An AF & tracking control circuit 27 for adjusting the position, an AF & tracking control circuit 28 for adjusting the focal position of the recording / reproducing beam to the target recording layer, and a microprocessor 29 for comprehensively controlling servo control, recording power control, etc. It is equipped with.

  The recording / reproducing apparatus 100 has a small aberration in the spherical aberration correction plate 7 in conjunction with the actuator for adjusting the position of the objective lens 9, the moving device for moving each lens of the relay lens 5, and the relay lens 5. An automatic correction mechanism for applying a voltage so that the laser spot is moved in the radial direction of the three-dimensional recording medium 8, and a rotation device for rotating the three-dimensional recording medium 8. These are not shown in the figure.

  In the present embodiment, the high-power semiconductor laser 1 having a wavelength (λ) of 405 nm is used as a recording / reproducing beam. However, the present invention is not limited to this, and a high-power laser having a wavelength (λ) of 250 nm to 450 nm is used. It may be used. Furthermore, the light source is not limited to a high-power semiconductor laser, and a gas laser or another structure laser can be used. The wavelength of the recording beam is preferably a wavelength having a large absorption rate in the recording layer of the three-dimensional recording medium.

  In the three-dimensional recording medium, a servo layer 31 is formed on a polycarbonate substrate 30, a recording film 32 capable of three-dimensional recording is formed thereon, and sandwiched by a cover layer 33 of a 0.1 mm transparent protective plate. It has a structure.

  In this embodiment, an acrylic resin is used as the recording film 32 capable of three-dimensional recording in order to use two-photon absorption. However, the recording film 32 using a photorefractive effect or an object using the photochromism effect is irradiated with a beam. Any optical constant such as the reflectance or refractive index of the portion can be used in the present invention.

  Here, an actual recording / reproducing operation will be described based on FIG. 1, but only a recording operation when the recording medium 8 is set in the recording / reproducing apparatus 100 for the first time will be described in detail as an example.

  First, when the recording medium 8 is set, the recording medium 8 is rotated to a target rotational speed. When the rotation speed reaches a certain number, the servo beam is irradiated on the surface of the servo layer 31 on the recording track at the reference radius position (initial adjustment area) to perform AF and tracking. At the same time, the lens on the recording medium side of the relay lens 5 is moved so that the focal position of the recording / reproducing beam matches the surface of the same servo layer 31. (Here, by moving only the lens on the recording medium side of the relay lens 5, the beam focal position for recording / reproducing can be reliably controlled without changing the position where the parallel light is focused in the relay lens). Parameters (recording medium side lens position of the relay lens 5, focus servo gain, etc.) in a state where the recording / reproducing beam AF is applied to the servo layer 31 by the Tr control circuit 28 are stored in the internal memory in the recording / reproducing apparatus 100. Keep it.

  Next, the servo layer 31 is AF-controlled on the servo layer 31 based on the servo beam, and the recording medium side lens in the relay lens 5 is moved at the same time as the tracking is completed. As a result, the focal position of the recording / reproducing beam is raised from the surface of the servo layer 31 to the position of the virtual first recording layer. At this time, if the relationship between the moving distance of the focal position of the recording / reproducing beam and the moving distance of the lens on the recording medium side in the relay lens 5 is obtained in advance, the movement to the target recording layer can be performed quickly.

At this time, since the focal position of the recording / reproducing beam moves in the depth direction in the recording film 32, the amount of spherical aberration changes. This spherical aberration is proportional to NA ⁴ × d / λ, where d is the thickness of the layer and λ is the wavelength of the beam. That is, by moving the recording / reproducing beam, the total thickness of the cover layer 33 and the recording film 32 between the objective lens 9 and the focal position of the recording / reproducing beam is changed, and the total of the changed layers is changed. It is necessary to correct spherical aberration depending on the thickness. Therefore, in the present invention, the liquid crystal element 7 is used to correct the spherical aberration. Since the liquid crystal element 7 has anisotropy in dielectric constant and refractive index, the refractive index changes depending on the voltage applied to the liquid crystal element 7. By utilizing this physical property, spherical aberration is corrected.

  At this time, when the focus of the recording / reproducing beam is moved to the first recording layer, 20 μm from the lens position (reference position) on the recording medium side of the relay lens 5 in the state where the surface of the servo layer 31 is in focus. If the lens on the recording medium side is moved to some extent, correction is performed by applying a voltage to the liquid crystal element 7 by the correction amount when the deviation is 10 μm based on the voltage correction distribution data stored in the internal memory of the recording apparatus 100. . In this embodiment, correction data when 13 μm is shifted from the reference position by 60 μm is stored (13 data). In this case, when the groove depth of the unevenness of the servo layer is sufficiently large, it is necessary to correct the aberration in consideration of the groove depth.

  Furthermore, the optimum aberration correction amount corresponding to the moving amount of the focal position of the recording / reproducing beam is obtained again from the state where the two beams are focused on the servo layer, and recording / reproducing in the recording medium is performed based on the calculated value. Aberration correction may be automatically performed according to the distance moved from the reference position of the beam. In this case, spherical aberration can be corrected more reliably.

  Further, by providing a pinhole 6 at a focal point in the relay lens 5 as in the present embodiment, a reflected beam other than a reflected beam from a recording mark or the like in the target recording layer is removed by this pinhole. And a reliable reproduction signal can be obtained. Further, since only the lens on the recording medium side of the relay lens 5 is moved, there is no change in the position where the parallel light is focused in the relay lens 5, so that the focal position of the recording / reproducing beam is moved to the position of the pinhole 6. There is no need to move it every time.

A recording / reproducing method for recording layers after the recording layer 1 will be described with reference to FIG.
FIG. 2 is a medium cross-sectional view for explaining the trajectory of the recording / reproducing beam when recording is performed on the three-dimensional recording medium in the present embodiment. It is assumed that a plane substantially perpendicular to the incident direction of the laser beam is a recording layer (virtual recording layer), and a recording track for forming recording marks concentrically on this recording layer, that is, a convex for servo. Recording tracks corresponding to the portion 34 and the concave portion 35 are set. This recording track is a virtual recording track in which the shape such as unevenness is not changed. For the sake of clarity, FIG. 2 shows a cross-sectional view of the recording medium when recording marks are formed on all the recording tracks. Here, the operation in the case of reproduction will be described in detail.

  First, the objective lens 9 is moved to the radial position of the recording track to be recorded while rotating the recording medium 8. Then, for example, the recording / reproducing beam (solid line) is focused on the recording mark (1) which is the reproduction starting point. At this time, the servo beam (dotted line) is focused on the surface of the servo layer. Here, by moving the lens on the recording medium side of the relay lens 5, the focal position of the recording / reproducing beam is raised from the surface of the servo layer 31 to the position of the virtual first recording layer. At this time, if the relationship between the moving distance of the focal position of the recording / reproducing beam and the moving distance of the lens on the recording medium side in the relay lens 5 is obtained in advance, the movement to the target recording layer can be performed quickly. However, even if the focal position of the recording / reproducing beam is moved to a target position, the recording mark (1) of the first recording layer 36 may not be focused. 28 is surely adjusted. In some cases, tracking to the recording mark row may be performed by the recording / reproducing beam control circuit 28. Next, when the recording medium 8 makes one rotation while reproducing the recording mark row on the same recording track as the recording mark (1) (here, on the recording track corresponding to the convex portion 34), the same goes through the recording mark (1) '. In this embodiment, an “interlayer switching region” (described with reference to FIG. 4) is formed before making one rotation and returning to the original position. The distance between the recording marks d in the depth direction (this distance varies depending on the material of the recording film, but this value is stored in advance in the internal memory of the recording / reproducing apparatus 100) is moved toward the objective lens 9 and recorded. With respect to the mark (1), the recording mark (2) of the third recording layer 37 separated by a distance d is reproduced. Similarly, reproduction is performed only on the recording track on the convex portion 34 of the servo layer 31 (up to the fifth recording layer 38 in this figure). Then, after the fifth recording layer 38 is reproduced, it moves to the recording track corresponding to the concave portion 35 of the servo layer 31 at the same place as the “interlayer switching region”.

  This is because a “recording track switching area” (described in FIG. 4) is provided. In this “recording track switching area”, the reproducing beam moves to the recording track on the inner circumference side and also moves to the position of the sixth recording layer 39 to reproduce the recording mark (4). That is, in the “recording track switching area”, the recording medium moves in the depth direction by a half distance between the recording marks (in this embodiment, half of the distance d between the recording marks is between the recording layers: d / 2).

  Similarly, when the recording medium 8 makes one rotation while reproducing the recording mark row on the same recording track as the recording mark (4) (here, on the recording track corresponding to the recess 35), the same goes through the recording mark (4) '. In this embodiment, the distance between the recording marks in the depth direction (this distance varies depending on the material of the recording film) is moved toward the recording medium 8 in the “interlayer switching region”. With respect to the recording mark (4), the recording mark (5) of the fourth recording layer 40 separated by a distance d is reproduced. Similarly, reproduction is performed only on the recording track on the concave portion 35 of the servo layer 31 (up to the second recording layer 41 in this figure). Then, after reproducing the second recording layer 41, in the “recording track switching area”, the reproducing beam moves to the recording track on the inner circumference side and also moves to the position of the first recording layer 36 to reproduce the recording mark (7). To do. In other words, in the “recording track switching area”, the recording medium is moved by a half distance between the recording marks in the depth direction. By repeating this operation, for example, reproduction can be continuously performed on the inner circumference side. However, when the recording track is switched in the radial direction (for example, beam movement from the convex portion 34 to the concave portion 35 of the servo layer 31), it is necessary to simultaneously change the tracking polarity of the servo beam. As described above, even if the recording medium rotates on the same radius, there is no beam movement in the radial direction, and the focal point of the recording / reproducing beam moves only in the depth direction. Therefore, the concave and convex grooves formed in the servo layer are preferably concentric. As a result, the objective lens finally performs recording by shifting the recording mark of the recording track adjacent in the radial direction to each recording mark by about half the distance between the recording marks in the depth direction, as shown in FIG. In other words, it is possible to record at the highest density in the three-dimensional recording. That is, a high density of about 13.4% can be achieved in the radial direction (described in FIG. 3).

  FIG. 3 shows that the arrangement of the recording marks recorded on the three-dimensional recording medium in this embodiment can be made higher in density than the conventional arrangement. FIG. 3 (A) shows a pattern that can be recorded with the highest density as a prior art in which the range that has some influence on other marks is spherical (between recording marks: d). On the other hand, FIG. 3B shows a layout of the recording marks of the present invention. In the present invention, in order to increase the density in a range that does not have any influence from other marks, the recording marks on the recording tracks adjacent in the radial direction are shifted in the depth direction with respect to the individual recording marks. ing. At this time, as shown in FIG. 3B, it is most efficient to shift by half the distance d between the recording marks (here, the distance between the layers). When calculated, a high density of about 13.4% can be achieved in the radial direction (cos30 ° = 0.866 = 86.6%). As a result, no recording mark is formed on the recording tracks on both sides in the radial direction of the recording track. Furthermore, it is possible to further increase the density by forming the recording marks so that the recording marks do not overlap on the upper and lower recording tracks. In order to simplify the calculation, the range that has some effect on other marks is made spherical, but in reality the range that the beam affects is an oval that is long in the depth direction. However, basically, the higher the density, the higher the density recording becomes possible.

  In FIG. 3, when attention is paid to the depth direction, it can be seen that the present invention is thicker than the prior art by half the thickness d between the recording marks. However, in order to increase another layer in the prior art, a thickness corresponding to the distance d between recording marks is required. That is, in recording for three layers, it may be within 3d. In the present technology, the required thickness in the depth direction is 2.5d, so it can be said that the capacity is the same. In addition, as the number of layers in the depth direction increases, the ratio of the extra d / 2 thickness to the whole decreases.

  Further, when the recording mark is shifted in the depth direction, it is preferable to correspond to the servo unevenness. That is, the recording track just below the concave portion 35 is displaced by 1/2 layer in the depth direction from the recording track just below the convex portion 34. This is preferable because the distance from the servo track is almost constant and the recording / reproducing margin is increased (when the depth of unevenness of the servo layer is shallow).

  Although it is possible to further increase the density by controlling the positional relationship between the recording marks formed on the upper and lower recording tracks, it is actually difficult to actually control, as in this embodiment. It is preferable from the viewpoint of the apparatus to control the positional relationship between adjacent recording tracks.

  FIG. 4 shows an example of the “interlayer switching region” when information on a recording medium that has already been recorded is continuously reproduced from the first layer as an example for explaining the recording / reproducing method of this embodiment. It is shown about the case where it forms in the same position of a horizontal direction (it is a sectional view of the circumference direction unlike FIG. 2).

  For example, from the point A of the recording track having a certain radius while rotating the recording medium 8 (for example, corresponding to the recording mark (1) in the first layer 36 on the convex portion 34 of the servo layer 31 shown in FIG. 2). When recording starts and makes one turn while recording at the same planar depth, the point B is reached. In a region called “interlayer switching region”, the recording beam moves in the direction opposite to the depth direction of the recording medium (upward in this figure) by the distance between the recording marks d in the depth direction. That is, the interlayer movement is performed while the recording medium rotates once. Then, recording is continued from point C (for example, corresponding to the recording mark (2) of the third layer 37 in FIG. 2). In this way, each time the recording medium rotates once, the interlayer movement is repeated in this “interlayer switching area”, and reproduction is continuously continued in the depth direction of the recording medium. However, “recording” formed with DC (continuous) marks is formed in the depth direction from the point D of the last recording track by a half distance between the recording marks d and to the adjacent recording track (corresponding to the concave portion of the servo area). It moves on the “track switching area” 44 while performing AF & tracking control. After moving to the adjacent recording track in this way, the reproduction is continuously performed in the depth direction (downward in this figure) as shown in FIG. That is, recording is started from point E (for example, corresponding to the recording mark (4) in the sixth layer 39 on the concave portion 35 of the servo layer 31 shown in FIG. 2), and recording is performed at the same planar depth position. However, if you go around, you will come to point F. Then, in the “interlayer switching region”, the focal position of the recording beam is moved in the depth direction of the recording medium by the distance between the recording marks d. Then, the reproduction is continued from the point G. In this way, reproduction is continuously continued in the depth direction of the recording medium. However, from the point H of the last recording track, it moves to the next recording track (corresponding to the convex portion of the servo area) while servoing the “recording track switching area” by a distance half the distance d between the recording marks. . Thereafter, the target information is continuously recorded in the radial direction in the recording medium in the same manner as in FIG.

  FIG. 6 shows an example of the “interlayer switching area” in detail. In the present invention, at least the AF pull-in portion 45 and the interlayer switching portion 46 are provided in this interlayer switching region. This enables high-speed access during playback. That is, with the AF applied to the servo layer, the recording / reproducing beam is moved from the servo layer surface to the recording film side, and AF control is performed by the AF drawing area of the target layer. In this case, AF can be applied to the AF pull-in unit 45 in the target interlayer switching region by counting the number of reproduction signals from the interlayer switching unit 46 or calculating the distance from the servo layer surface. Therefore, in order to reliably obtain a reproduction signal from the interlayer switching region, it is preferable that the length of the interlayer switching unit 46 is at least half that of the interlayer switching region. Also, by providing the layer information section 47, it is possible to know how many layers and what layer the switching area is between. The layer information unit 47 may be a wobble of a DC (continuous) mark. Here, in order to perform reliable interlayer movement, the AF pull-in area 45 and the interlayer switching area 46 are formed by DC (continuous) marks. Furthermore, it is preferable to make the DC (continuous) mark width wider than the width of the recording mark because a larger reproduction signal can be obtained.

  FIG. 7 shows an example when the interlayer switching region is shifted in the circumferential direction. That is, every time the recording beam makes a round of the recording track at the same radial position, the switching area corresponding to each layer is shifted in the circumferential direction by a distance of d between recording marks. This figure shows the case of eight layers, and three switching regions are formed in the circumferential direction corresponding to each layer. This switching area requires ((number of recording layers / 2) -1). Further, when shifting in the circumferential direction as described above, a “recording track switching area” is also required. Although there is a demerit that the area that can be recorded is reduced in this way, there is also an advantage that high-speed access to the target layer is possible. That is, depending on which position in the circumferential direction of the servo layer the reflected light corresponding to the interlayer switching region can be detected by moving the focal position of the recording / reproducing beam in the depth direction with AF applied to the servo layer. Thus, it is possible to move instantaneously without counting the number of interlayer switching areas from the AF servo layer.

  Further, the present invention can be applied to a multilayer type recording medium in which narrow recording layers having a thickness of about several μm are stacked, even if the recording medium is not in a bulk state as in this embodiment.

  In this embodiment, the recording / reproducing method has been described while moving in the depth direction every rotation. For example, recording / reproduction is performed by moving to the recording track in the radial direction every rotation in the same plane. Also in the method, the recording layer may be continuously moved to another recording layer by the “interlayer switching unit” which is a feature of the present invention at the innermost periphery or the outermost periphery of the recording area. In this case as well, the recording density can be increased by forming the recording marks by shifting the protrusions and the recesses by half the distance between the recording marks as in the present invention.

Configuration diagram of recording / reproducing apparatus in this embodiment The figure which showed an example of the arrangement | positioning figure of the recording mark in a present Example Comparison of recording mark arrangement between this example and conventional example Explanatory drawing of the interlayer switching area in this embodiment (convex part) Explanatory drawing of the interlayer switching area in this embodiment (recess) The figure which showed the detail of the interlayer change area in this example (convex part) Example diagram (convex part) where the interlayer switching region in this embodiment is displaced in the circumferential direction

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High power semiconductor laser for recording / reproducing 2 Collimating lens 3, 10, 28 Polarizing beam splitter 4 λ / 4 plate 5 Relay lens 6 Pinhole 7 Spherical aberration correction plate (liquid crystal element)
8 Three-dimensional recording medium 9 Objective lens 10 Spherical aberration correction plate (liquid crystal panel)
11, 13, 17, 22 Aperture lens 12, 15, 24 Detector 14, 23 Cylindrical lens 15 Semiconductor laser for AF control 16 Semiconductor laser for servo 20 Dichroic mirror 21 Reflection mirror 25, 26 Laser driver 27, 28 AF & tracking control circuit 29 Microprocessor 30 Polycarbonate substrate 31 Servo layer 32 Recording film 33 Cover layer 34, 42 Convex part 35, 43 Concave part 36, 37, 38, 39, 40, 41 Virtual recording layer 44 Recording track switching part 45 AF lead-in part 46 Interlayer Switching unit 47 Layer information unit 100 Recording device

Claims (58)

  A recording / reproducing apparatus for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information and the like and capable of recording data in the depth direction. A servo light source for irradiating the beam and a recording / reproducing light source for irradiating the recording layer in the recording medium, and the focal position of each beam emitted from each light source can be controlled; During recording or reproduction of information by the beam for recording, the recording mark in the depth direction in the recording medium is formed or the layer movement to another recording layer to be formed is performed in a predetermined area on the servo layer. An information recording / reproducing apparatus characterized in that it is executed only.   2. An information recording / reproducing apparatus according to claim 1, wherein during recording or reproduction of information by the recording / reproducing beam, movement between layers to another recording layer separated by a distance between recording marks in the depth direction is performed on the recording medium. The information recording / reproducing apparatus is characterized in that the execution is completed during one rotation.   2. The information recording / reproducing apparatus according to claim 1, wherein during recording or reproduction of information by the recording / reproducing beam, inter-layer movement to another recording layer separated by a distance between recording marks in the depth direction is recorded. An information recording / reproducing apparatus, which is executed each time a medium rotates once.   4. The information recording / reproducing apparatus according to claim 3, wherein an area for performing interlayer movement to another recording layer separated by a distance between recording marks in the depth direction is defined in the depth direction ((recording Number of layers / 2) -1) An information recording / reproducing apparatus characterized by being formed.   4. The information recording / reproducing apparatus according to claim 3, wherein an area for performing interlayer movement to another recording layer separated by a distance between recording marks in the depth direction does not overlap in the depth direction at the same radius. An information recording / reproducing apparatus characterized by that. 2. The information recording / reproducing apparatus according to claim 1, wherein during recording or reproduction of information by the recording / reproducing beam, the layer information is moved to another recording layer separated by a distance between recording marks in the depth direction. A recording / reproducing apparatus for recording or reproducing information.   2. The information recording / reproducing apparatus according to claim 1, wherein the movement to the adjacent recording track in the radial direction in the recording medium during recording or reproduction of information by the recording / reproducing beam emitted from the recording / reproducing light source is performed in the servo layer. An information recording / reproducing apparatus, wherein the information recording / reproducing apparatus is executed only in a predetermined area above.   8. The information recording / reproducing apparatus according to claim 7, wherein when moving to the lowermost layer or the uppermost layer of the recording layer in the recording medium, the movement to the adjacent recording track in the radial direction is simultaneously performed. Recording and playback device.   9. The information recording / reproducing apparatus according to claim 8, wherein, when moving to the adjacent recording track in the radial direction, the information recording / reproducing apparatus moves by about half the distance between the recording marks in the depth direction. .   2. The information recording / reproducing apparatus according to claim 1, wherein in the case of a recording medium which has never been recorded, recording is performed in order from a recording layer close to the servo layer.   2. The information recording / reproducing apparatus according to claim 1, wherein the information recording / reproducing by the recording / reproducing beam emitted from the recording / reproducing light source is positioned on the same plane during most of the rotation of the recording medium. An information recording / reproducing apparatus characterized in that the information recording / reproducing apparatus is performed.   A recording / reproducing apparatus for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information and the like and capable of recording data in the depth direction. A servo light source for irradiating the beam and a recording / reproducing light source for irradiating the recording layer in the recording medium, and the focal position of each beam emitted from each light source can be controlled. Beam position varying means in the depth direction for aligning the beam emitted from the recording / reproducing light source to the recording layer, and the relationship between the focal position moving distance and the spherical aberration amount is obtained in advance and emitted from the recording / reproducing light source. An information recording / reproducing apparatus comprising an aberration correction mechanism for automatically performing aberration correction in accordance with a distance by which a focal position of the beam is moved in the recording layer direction from the servo layer surface.   13. The information recording / reproducing apparatus according to claim 12, wherein a relay lens is used to vary the focal position of the beam emitted from the recording / reproducing light source in the depth direction.   14. The information recording / reproducing apparatus according to claim 13, wherein only the lens on the recording medium side of the relay lens is moved in order to vary the focal position of the beam emitted from the recording / reproducing light source in the depth direction. Information recording / reproducing apparatus.   14. The information recording / reproducing apparatus according to claim 13, wherein a pinhole is installed at a position in the relay lens that is in focus.   13. The information recording / reproducing apparatus according to claim 12, wherein a liquid crystal element is used for correcting the aberration.   13. The information recording / reproducing apparatus according to claim 12, wherein the recording medium set in the recording / reproducing apparatus for the first time is emitted from a servo light source and a recording / reproducing light source on a servo layer having a radius set first. Information characterized by having AF control means for automatically adjusting each beam in focus, and means for storing parameter values (relay lens position, focus servo gain, etc.) at that time in a memory in the apparatus Recording and playback device.   18. The information recording / reproducing apparatus according to claim 17, wherein the position of the lens on the recording medium side of the relay lens in a state in which each beam emitted from the servo light source and the recording / reproducing light source is focused on the servo layer. An information recording / reproducing apparatus characterized in that, as a reference, when a beam emitted from a recording / reproducing light source moves in the recording layer direction, an aberration correction amount is controlled by a change in a lens position on the recording layer side.   18. The information recording / reproducing apparatus according to claim 17, wherein in the recording medium set in the recording / reproducing apparatus for the first time, the two light beams emitted from the servo light source and the recording / reproducing light source are focused on the servo layer. In this state, the optimum aberration correction amount corresponding to the movement amount of the focal position of the recording / reproducing beam is obtained again, and based on the value, the amount of movement from the reference position of the recording / reproducing beam in the recording medium is determined. An information recording / reproducing apparatus characterized in that aberration correction is automatically performed.   A recording / reproducing apparatus for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information and the like and capable of recording data in the depth direction. A servo light source for irradiating the beam and a recording / reproducing light source for irradiating the recording layer in the recording medium, and the focal position of each beam emitted from each light source can be controlled; An information recording / reproducing apparatus characterized in that in recording by a recording / reproducing beam emitted from a light source for recording, recording is performed by shifting a recording mark of a recording track adjacent in the radial direction with respect to each recording mark in the depth direction.   21. The information recording / reproducing apparatus according to claim 20, wherein recording is performed by shifting a recording mark of a recording track adjacent in a radial direction with respect to each recording mark by about a half of a distance between recording marks in a depth direction. Information recording / reproducing apparatus.   21. The information recording / reproducing apparatus according to claim 20, wherein the servo layer is formed of a convex portion and a concave portion, and a recording mark closest to the servo layer corresponding to the convex portion of the servo layer and a convex portion of the servo layer are formed. Recording and reproduction of information, wherein recording is performed such that the distance between the recording mark closest to the servo layer corresponding to the concave portion of the servo layer and the concave portion of the servo layer is greater than the distance. apparatus.   An information recording / reproducing method for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information in advance and is capable of recording data in the depth direction. Focus on the servo layer to control the radial position, and at least the recording and playback beam can focus on the recording layer and control the position in the depth direction to perform recording and playback at the target location. During recording or reproduction of information by the recording / reproducing beam, a recording mark in the depth direction in the recording medium is formed or moved to another recording layer to be formed on the servo layer. An information recording / reproducing method characterized in that the information recording / reproducing method is executed only in a predetermined area.   24. The information recording / reproducing method according to claim 23, wherein during recording or reproduction of information by the recording / reproducing beam, interlayer movement to another recording layer separated by a distance between recording marks in the depth direction is performed on the recording medium. The information recording / reproducing method is characterized in that execution is completed during one rotation.   24. The information recording / reproducing method according to claim 23, wherein during recording or reproduction of information by the recording / reproducing beam, inter-layer movement to another recording layer separated by a distance between recording marks in the depth direction is recorded. An information recording / reproducing method, which is executed every time the medium rotates once.   26. The information recording / reproducing method according to claim 25, wherein an area for performing interlayer movement to another recording layer separated by a distance between recording marks in the depth direction is defined in the depth direction ((recording Number of layers / 2) -1) Information recording / reproducing method, characterized in that it is formed.   26. The information recording / reproducing method according to claim 25, wherein an area for performing interlayer movement to another recording layer separated by a distance between recording marks in the depth direction does not overlap in the depth direction at the same radius. An information recording / reproducing method characterized by the above.   24. The information recording / reproducing method according to claim 23, wherein during recording or reproduction of information by the recording / reproducing beam, the layer information is moved to another recording layer separated by a distance between recording marks in the depth direction. A method for recording and reproducing information, characterized by recording or reproducing information.   24. The information recording / reproducing method according to claim 23, wherein the movement to the adjacent recording track in the radial direction in the recording medium during recording or reproduction of information by the recording / reproducing beam emitted from the recording / reproducing light source is performed by the servo layer. An information recording / reproducing method characterized in that the information recording / reproducing method is executed only in the above-specified region.   30. The information recording / reproducing method according to claim 29, wherein when moving to the lowermost layer or the uppermost layer of the recording layer in the recording medium, the movement to the adjacent recording track in the radial direction is simultaneously performed. Recording and playback method.   31. The information recording / reproducing method according to claim 30, wherein when moving to the adjacent recording track in the radial direction, the information is moved by about half the distance between the recording marks in the depth direction. .   24. The information recording / reproducing method according to claim 23, wherein in the case of a recording medium that has never been recorded, recording is performed in order from a recording layer close to the servo layer.   24. The information recording / reproducing method according to claim 23, wherein the information recording / reproducing by the recording / reproducing beam is performed at a position on the same plane during most of the rotation of the recording medium. Recording and playback method.   An information recording / reproducing method for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information in advance and is capable of recording data in the depth direction. Focus on the servo layer to control the position in the radial direction, and at least the recording and playback beam can focus on the recording layer and control the position in the depth direction to perform recording and playback at the target location Yes, if the beam focal position in the depth direction is moved in order to match the recording / reproducing beam to at least the target recording layer, the movement distance and spherical aberration of the focal position of the recording / reproducing beam obtained in advance An information recording / reproducing method, wherein aberration correction is automatically performed in accordance with the distance that the focal position of the recording / reproducing beam moves in the direction of the recording layer from the servo surface.   35. The information recording / reproducing method according to claim 34, wherein the focal position of the recording / reproducing beam is varied in the depth direction using a relay lens in the information recording / reproducing method.   36. The information recording / reproducing method according to claim 35, wherein only the lens on the recording medium side of the relay lens is moved to vary the focal position of the recording / reproducing beam in the depth direction. .   36. The information recording / reproducing method according to claim 35, wherein a pinhole is provided at a location where the relay lens is in focus.   35. The information recording / reproducing method according to claim 34, wherein the aberration correction is performed using a liquid crystal element.   35. The information recording / reproducing method according to claim 34, wherein in the recording medium set in the recording / reproducing apparatus for the first time, the focus of both the servo beam and the recording / reproducing beam on the servo layer at the initially set radius. A method for recording / reproducing information, characterized in that AF is automatically adjusted so as to match, and parameter values (relay lens position, focus servo gain, etc.) at that time are stored in a memory in the apparatus.   40. The information recording / reproducing method according to claim 39, wherein the position of the lens on the recording medium side of the relay lens in a state where both the servo beam and the recording / reproducing beam are focused on the servo layer is used as a reference. An information recording / reproducing method characterized in that, when the recording / reproducing beam moves in the direction of the recording layer, the aberration correction amount is controlled by changing the lens position on the recording layer side.   40. In the information recording / reproducing method according to claim 39, in the recording medium set in the recording / reproducing apparatus for the first time, the servo light source and the two beams emitted from the recording / reproducing light source are focused on the servo layer. In this state, the optimum aberration correction amount corresponding to the movement amount of the focal position of the recording / reproducing beam is obtained again, and based on the value, the amount of movement from the reference position of the recording / reproducing beam in the recording medium is determined. A method of recording and reproducing information, characterized in that aberration correction is automatically performed.   An information recording / reproducing method for recording information on a recording medium using a three-dimensional recording medium that has a servo layer indicating position information in advance and is capable of recording data in the depth direction. Focus on the servo layer to control the radial position, and at least the recording and playback beam can focus on the recording layer and control the position in the depth direction to perform recording and playback at the target location. An information recording / reproducing method characterized in that in recording by the recording / reproducing beam, recording is performed by shifting a recording mark of a recording track adjacent in a radial direction with respect to each recording mark in a depth direction.   43. The information recording / reproducing method according to claim 42, wherein recording is performed by shifting a recording mark of a recording track adjacent in a radial direction to each recording mark by a half of a distance between recording marks in the depth direction. Information recording and playback method.   43. The information recording / reproducing method according to claim 42, wherein the servo layer is formed of a convex portion and a concave portion, and a recording mark closest to the servo layer corresponding to the convex portion of the servo layer and a convex portion of the servo layer are formed. Recording and reproduction of information, wherein recording is performed such that the distance between the recording mark closest to the servo layer corresponding to the concave portion of the servo layer and the concave portion of the servo layer is greater than the distance. Method.   In a three-dimensional recording medium that has a servo layer indicating position information in advance and is capable of recording data in the depth direction, recording in the depth direction in the recording medium during recording or reproduction of information by a recording / reproducing beam A three-dimensional recording medium characterized in that an area dedicated for interlayer movement is provided in a predetermined area on the servo layer in order to perform interlayer movement to another recording layer on which marks are formed or to be formed.   46. The three-dimensional recording medium according to claim 45, wherein another recording layer is separated by a distance between recording marks in the depth direction during one rotation of the recording medium during recording or reproduction of information by the recording / reproducing beam. The three-dimensional recording medium is characterized in that the interlayer movement is completed.   46. The three-dimensional recording medium according to claim 45, wherein each time the recording medium rotates during recording or reproduction of information by the recording / reproducing beam, to another recording layer separated by a distance between recording marks in the depth direction. A three-dimensional recording medium characterized by repeatedly moving between layers.   48. The three-dimensional recording medium according to claim 47, wherein an area for performing interlayer movement to another recording layer separated by a distance between recording marks in the depth direction is the same radius in the depth direction ((recording layer Number / 2) -1) A three-dimensional recording medium characterized by being formed.   48. The three-dimensional recording medium according to claim 47, wherein an area for performing interlayer movement to another recording layer separated by a distance between recording marks in the depth direction does not overlap in the depth direction at the same radius. A three-dimensional recording medium characterized by being formed.   46. The three-dimensional recording medium according to claim 45, wherein layer information is recorded in an area for performing interlayer movement to another recording layer.   46. The three-dimensional recording medium according to claim 45, wherein an area for moving to an adjacent recording track in the radial direction in the recording medium during recording or reproduction of information by the recording / reproducing beam is provided on the servo layer. A three-dimensional recording medium.   52. The three-dimensional recording medium according to claim 51, wherein an area for connecting to the lowermost or uppermost layer of the recording layer in the recording medium and moving to the adjacent recording track in the radial direction is provided. A three-dimensional recording medium.   53. The three-dimensional recording medium according to claim 52, wherein the moving distance to the adjacent recording track in the radial direction is about half of the distance between the recording marks in the depth direction.   46. The three-dimensional recording medium according to claim 45, wherein in the case of a recording medium that has never been recorded, the three-dimensional recording medium is recorded in order from a recording layer close to the servo layer.   46. The three-dimensional recording medium according to claim 45, wherein the recording mark formed by the recording / reproducing beam is formed at a position on substantially the same plane.   In a three-dimensional recording medium that has a servo layer indicating position information in advance and can record data in the depth direction, the recording mark of the recording track adjacent in the radial direction is shifted in the depth direction with respect to each recording mark. A three-dimensional recording medium characterized by being recorded.   57. The three-dimensional recording medium according to claim 56, wherein the three-dimensional recording medium is recorded with a deviation of half the distance between the recording marks in the depth direction. 57. The three-dimensional recording medium according to claim 56, wherein in the information recording medium, the servo layer is formed of a convex portion and a concave portion, and the recording mark closest to the servo layer corresponding to the convex portion of the servo layer and the servo It is characterized in that the distance between the recording mark closest to the servo layer corresponding to the concave portion of the servo layer and the concave portion of the servo layer is recorded with respect to the distance from the convex portion of the servo layer. A three-dimensional recording medium.

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