JP2010055715A - Recording and reproducing device and recording medium used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability to multi-layer record in a recording and reproducing device. <P>SOLUTION: The recording and reproducing device includes: a rotary drive means (motor) rotation-driving a recording medium 1 being multi-layers recordable; lenses 6, 7 for recording and reproducing arranged opposing to the recording medium 1 rotation-driven by this rotation-drive means, and a lens 5 for address detection; a light source for recording and reproducing for supplying light for recording and reproducing to the lenses 6, 7 for recording and reproducing; and a light source for address for supplying light for address to the lens 5 for address detection. Data of recording layer 1B, 2A, 2B being adjacent in the front and rear surfaces direction of this recording medium 1 out of a plurality of recording layers 1B, 2A, 2B provided in the prescribed interval, for example, between the front and rear surfaces of this recording medium 1 are shifted to a direction being orthogonal to the front and rear surfaces direction of this recording medium 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording / reproducing apparatus capable of multilayer recording and a recording medium used therefor.

  In recent years, recording media capable of multilayer recording have been proposed in order to increase the recording capacity.

  The recording / reproducing apparatus that performs recording / reproducing on the recording medium has the following configuration.

That is, the conventional recording / reproducing apparatus has a rotation driving means for rotating a recording medium capable of multi-layer recording, a lens disposed opposite to the recording medium rotated by the rotation driving means, and recording / reproducing light to the lens. The recording / reproducing light source to be supplied and the address light source for supplying the address light to the lens are provided. As a document describing a technique related to a conventional recording / reproducing apparatus, for example, there is Patent Document 1 below.
JP 2002-150567 A

  In the above conventional recording / reproducing apparatus, the recording medium is irradiated with the addressing light from the addressing light source via the lens, and the recording / reproducing light from the recording / reproducing light source is based on the obtained address. Light is irradiated onto a recording medium through a lens, thereby performing multilayer recording on the recording medium.

  A problem in such a conventional example is that a large amount of information can be recorded by increasing the recording density by performing multilayer recording on a recording medium, but the reliability for recording and reproduction is low.

  That is, the multi-layer recording on the recording medium is to provide a plurality of recording layers at predetermined intervals between the front and back surfaces of the recording medium, record data on each layer, and read and reproduce data from each layer.

  However, when attention is paid to the recording medium in this state, the data of the recording layers adjacent in the front and back direction of the recording medium are recorded in a state of being overlapped with the front and back direction, although there is a predetermined interval. Therefore, the reliability of recording and reproduction is low.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the reliability of recording and reproduction.

  In order to achieve this object, the present invention provides a rotational drive means for rotationally driving a recording medium capable of multi-layer recording, a recording / reproducing lens and an address arranged opposite to the recording medium rotationally driven by the rotational drive means. A detection lens; a recording / reproduction light source that supplies recording / reproduction light to the recording / reproduction lens; and an address light source that supplies address light to the address detection lens. Of the multiple recording layers provided at intervals, the data of the recording layer adjacent in the front and back direction of this recording medium is shifted in the direction orthogonal to the front and back direction of this recording medium, thereby achieving the initial purpose. To do.

  As described above, the present invention provides a rotational driving means for rotationally driving a recording medium capable of multi-layer recording, a recording / reproducing lens and an address detection lens arranged to face the recording medium rotationally driven by the rotational driving means, A plurality of recording / reproducing light sources for supplying recording / reproducing light to the recording / reproducing lens, and address light sources for supplying address light to the address detecting lens, provided at predetermined intervals between the front and back surfaces of the recording medium Among the recording layers, the recording layer data adjacent in the front and back direction of the recording medium are shifted in a direction orthogonal to the front and back direction of the recording medium, thereby improving the reliability of recording and reproduction. Will be able to.

  That is, in the present invention, among the plurality of recording layers provided at a predetermined interval between the front and back surfaces of the recording medium, the data of the recording layers adjacent in the front and back direction of the recording medium is changed to the front and back direction of the recording medium. Therefore, even in multi-layer recording, the data of adjacent recording layers does not overlap in the front and back directions, so that the reliability of recording and reproduction can be improved. .

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

(Embodiment)
FIG. 1 shows a recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a multi-layer recordable recording medium formed of, for example, a photopolymer. It has a disk shape as shown in (a), and a through hole (2 in FIG. 3 (a)) is provided at the center.

  Then, the rotational drive shaft 4 of the motor 3 is inserted into the through hole 2, and although not shown, chucking is performed in this state, whereby the recording medium 1 passes through the rotational drive shaft 4 and the motor 3 Thus, it is driven to rotate. That is, the motor 3 and the rotational drive shaft 4 constitute a rotational drive means.

  Returning to FIG. 1 again, the description will be continued. As shown in FIG. 1, an address detection lens 5 and a recording / playback lens 6 are provided on one surface side (for example, the lower surface side) of the recording medium 1. Opposing to the one surface side of the media 1, they are arranged side by side.

  A recording / reproducing lens 7 is arranged on the other surface side (for example, the upper surface side) of the recording medium 1 so as to face the recording / reproducing lens 6 with the recording medium 1 interposed therebetween.

  Next, the address detection lens 5, the recording / reproducing lens 6, and the recording / reproducing lens 7 will be described with reference to FIG.

  First, as shown in FIG. 2, the recording medium 1 is capable of multi-layer recording in the thickness direction, and as shown in FIG. 2, at the intersection of light by the recording and reproducing lenses 6 and 7. The interference of light produces so-called interference fringes that are recorded as changes in the properties of the media material, such as refractive index changes, which constitute part of the digital signal. The interference fringes are intermittently formed on one plane (in the inner layer) where the interference fringes are formed, whereby video and audio are recorded as digital signals.

  As will be described in detail later, as is clear from FIG. 2, a plurality of recording points in the thickness direction (between the front and back surfaces) of the disc-shaped recording medium 1 are defined at the intersections of the light by the recording and reproducing lenses 6 and 7. By moving to the plane, the video and audio are recorded as digital signals on the moved plane, and can be formed in a plurality of layers with respect to the thickness direction of the recording medium 1. Can be very large.

  For example, if the information of the surveillance camera is recorded on the recording medium 1, it is possible to record one year with the recording medium 1 and this makes the recording capacity extremely large. It will be understood.

  The address detection lens 5 is provided to perform the recording using the recording / reproducing lenses 6 and 7 and the subsequent reproduction. That is, as shown in FIG. 2, the address detection lens 5 reads an address 8 provided on the lower surface side of the recording medium 1, and uses the recording / reproducing lenses 6 and 7 described above based on the read address 8. Recording and subsequent playback.

  Next, the description will be continued with reference to FIG. 1 again regarding the light source and the like for recording using the recording and reproducing lenses 6 and 7 and subsequent reproduction and reading the address using the address detecting lens 5.

  In the present embodiment, the recording on the recording medium 1 and the subsequent reproduction and reading of the address using the address detection lens 5 are performed by one light source 9.

  That is, in the present embodiment, a laser that emits blue light having a wavelength of 405 nm is used as the light source 9.

  First, the blue light from the light source 9 is then subjected to the enlargement and rounding correction by the relay lens 10, then passes through the beam splitter 11, and then converted into parallel light by the collimator lens 12. Be changed. The parallel light is then converted into light having two mutually orthogonal polarization components (P-polarized light and S-polarized light) in the half-wave plate 13.

  Of the converted light, the P-polarized light passes through the beam splitter 14, then passes through the quarter-wave plate 15, the beam splitter 16, and the quarter-wave plate 17 one after another. The light passes through the detection lens 5 and is condensed to an address 8.

  The reflected light irradiated to the address 8 of the recording medium 1 and then reflected at the address 8 is detected as address information. This reflected light is detected by the address detecting lens 5 and then 1/4. After passing through the wave plate 17, the light enters the beam splitter 16, and is then reflected by 90 ° by the beam splitter 16, and the reflected light passes through the hologram 18 and is collected by the astigmatism lens 19. The emitted light reaches the address detection element 20.

  Then, the address information is detected based on the information that has reached the address detecting element 20, and based on this address information, the recording and reproducing by the recording / reproducing lenses 6 and 7 are performed.

  Here, the beam splitter 16 that reflects the reflected light from the recording medium 1 toward the address detection element 20 will be described in more detail.

  The beam splitter 16 separates light according to the rotation direction of circularly polarized light out of the polarization components of light. Particularly in this embodiment, the counterclockwise circularly polarized light passes through the beam splitter 16, and the clockwise circularly polarized light is reflected by the beam splitter 16.

  That is, the P-polarized light emitted from the light source 9 and passed through the beam splitter 14 passes through the quarter-wave plate 15 to become counterclockwise circularly polarized light and passes through the beam splitter 16.

  Then, the counterclockwise circularly polarized light that has passed through the beam splitter 16 passes through the quarter-wave plate 17 to become S-polarized light, passes through the address detection lens 5, is condensed, and is reflected by the recording medium 1. The

  Next, the S-polarized light reflected by the recording medium 1 passes through the address detecting lens 5 and then passes through the quarter-wave plate 17 to become clockwise circularly polarized light. The reflected light from the recording medium 1 that has become clockwise circularly polarized light enters the beam splitter 16, is then reflected by 90 degrees at the beam splitter 16, and travels toward the address detection element 20.

  As described above, in this embodiment, by using the beam splitter 16 that separates the light according to the rotation direction of the circularly polarized light, the P-polarized light that is linearly polarized light emitted from the light source 9 and separated by the beam splitter 14 is converted to 1 / 4 wavelength plate 15 is passed through as circularly polarized light, and ¼ wavelength plate 17 is passed through twice, and when passing through ¼ wavelength plate 15, the direction of travel is as circularly polarized light that is reverse to that when passing through ¼ wavelength plate 15. Can be changed.

  In other words, by using the beam splitter 16 that separates the light according to the rotation direction of the circularly polarized light together with the quarter wavelength plates 15 and 17, it is possible to change the traveling direction of the linearly polarized light having a single wavelength. Become.

  In the present embodiment, as described above, recording by the recording / reproducing lenses 6 and 7 and subsequent reproduction are performed based on the address information detected by the address detecting element 20.

  Specifically, the S-polarized light of the light passing through the half-wave plate 13 is reflected by the beam splitter 14 at a right angle to the left side of FIG. The light passes through the quarter-wave plate 22 and the spherical aberration correction element 23 one after another, and then is condensed in the recording medium 1 by the recording / reproducing lens 6, and then spreads from its focal point before recording / reproducing. It is converted into parallel light again by the lens 7 for use.

  The parallel light converted by the recording / reproducing lens 7 then passes through the spherical aberration correction element 24 and the shutter 25, and then proceeds to the retroreflector 26. After being reflected by the retroreflector 26, the parallel light is converted into the shutter 25 and spherical aberration. After passing through the correction element 24, the light is condensed by the recording / reproducing lens 7, and is focused in the recording medium 1 as shown in FIGS.

  At this time, since the focal point by the recording / reproducing lens 6 is already formed on the set recording surface in the recording medium 1, the focal point by the recording / reproducing lens 7 interferes, and as a result, As described above, interference fringes are formed in the recording medium 1.

  Next, drive systems for the address detection lens 5, the recording / reproducing lens 6, and the recording / reproducing lens 7 will be described. That is, the address detection lens 5 needs to adjust the focal length with the recording medium 1 in order to appropriately read the address 8 of the recording medium 1, and the recording / reproducing lenses 6 and 7 are set. It is necessary that the focal points of the recording surfaces are correctly formed on the recording surface, and these recording / reproducing lenses 6 and 7 need to perform multilayer recording in the thickness direction of the recording medium 1, Drive control is required.

  First, as can be understood from FIGS. 2 and 3B, the recording / reproducing lens 6 and the address detecting lens 5 are unitized by being housed in a frame 27. 3A, the recording medium 1 is moved in the radial direction as shown in FIG. 3A by being driven by the screw shaft 28 shown in FIG. 3A and driving the screw shaft 28 by the motor 29 shown in FIG. . The quarter wavelength plate 17 is held on the frame 27 at a constant distance from the address detection lens 5, and the spherical aberration correction element 23 is kept at a constant distance from the recording / reproducing lens 6. Is held. For this reason, in the present embodiment, the position information of the address detecting lens 5 and the position information of the recording / reproducing lens 6 with respect to the recording medium 1 are obtained by using the quarter wavelength plate 17 and the spherical aberration correcting element 23. ing.

  In this case, the address detecting lens 5 is arranged on the upstream side of the recording medium 1 relative to the recording / reproducing lens 6. In this state, electromagnetic coils 30 for moving the frame 27 are provided at the four corners of the frame 27 in order to adjust the distances between the address detection lens 5, the recording / reproducing lens 6 and the recording medium 1. Yes.

  Further, in order to finely adjust individual distances between the recording medium 1, the address detection lens 5, and the recording / reproducing lens 6, electromagnetic coils are provided at the four corners of the address detecting lens 5 and the recording / reproducing lens 6, respectively. 31 and 32 are provided.

  On the other hand, the recording / reproducing lens 7 disposed above the recording medium 1 is driven in the radial direction of the recording medium 1 by driving the screw shaft 33 with a motor 34, as can be understood from FIGS. Driving is performed, and the distance to the recording medium 1 is adjusted by energizing the electromagnetic coil 35.

  In the above configuration, first, when the address 8 is detected by the address detection lens 5, the address detection lens 5 is attached to the electromagnetic coil 30 so that the focus on the address detection element 20 is most appropriate as described above. , 31, where a correct address 8 is read by performing so-called servo control.

  Next, the control for causing the focal points of the recording / reproducing lenses 6 and 7 to interfere with each other will be described. The light after the interference fringes are formed by the recording / reproducing lenses 6 and 7 is the recording / reproducing lens. 6. Next, after passing through the spherical aberration correcting element 23, the quarter wavelength plate 22, then the mirror 21, and the beam splitter 14, and then passing through the quarter wavelength plate 36 and the astigmatism lens 37, the light receiving element 38 Is detected.

  Then, by performing servo control on the recording / reproducing lenses 6 and 7 using the electromagnetic coils 31 and 35 based on the detection data in the light receiving element 38, the target depth of the recording medium 1 is obtained as described above. Control is performed so that an appropriate interference fringe is formed in this layer.

  In the present embodiment, as described above, in addition to the recording medium 1 capable of multi-layer recording, compatibility for performing writing and reading to a so-called CD or DVD is also provided.

  Specifically, as shown in FIG. 1, a light source 39 capable of emitting infrared light for CD and red light for DVD is provided in a direction orthogonal to the relay lens 10 of the beam splitter 11.

  This compatibility will be briefly described. First, when recording or reproducing a CD, as described above, the light source 39 emits infrared light. Further, when recording or reproducing a DVD, as described above, the light source 39 emits red light. Of course, at this time, a CD or DVD is mounted on the rotational drive shaft 4 of FIG.

  At these times, the light emitted from the light source 39 then travels to the beam splitter 11 via the diffraction grating 40.

  Here, the diffraction grating 40 is for splitting the infrared light for CD emitted from the light source 39 and the red light for DVD into three lights, respectively. By separating the light emitted from the light source 39, the servo control of the recording / reproducing lens 6 can be performed with high accuracy, and the recording / reproducing quality can be improved (these CDs and DVDs). The recording / reproducing of the data will be described in detail later).

  Hereinafter, recording / reproduction on the recording medium 1 and recording / reproduction on a CD or DVD instead of the recording medium 1 will be described.

  First, recording / reproduction on the recording medium 1 capable of multilayer recording will be described with reference to FIGS.

  In this case, the number of layers of the recording medium 1 to be recorded or the number of layers from which reading is to be performed is first set. This setting is shown in FIG.

  In FIG. 4, the P-polarized light of the light that has entered the beam splitter 14 from the light source 9 goes straight as described above, becomes circularly polarized light by the quarter-wave plate 15, passes through the beam splitter 16, and then becomes ¼. After being changed to S-polarized light by the wave plate 17, it goes to the address detection lens 5 as described above.

  At this time, a part of the light is reflected by the surface of the quarter-wave plate 17, and the reflected light passes through the beam splitter 16 as shown in FIG. The polarized light is reflected by the beam splitter 14 and then reaches the light receiving element 38 via the quarter wavelength plate 36 and the astigmatism lens 37.

  On the other hand, the S-polarized light traveling from the half-wave plate 13 to the beam splitter 14 is reflected in the direction of the mirror 21 as shown in FIG. 4, and then becomes circularly-polarized light by the quarter-wave plate 22, and then is spherical as described above. It proceeds to the recording / reproducing lens 6 via the aberration correction element 23.

  At this time, part of the light is also reflected by the surface of the spherical aberration correction element 23, and this reflected light becomes P-polarized light by the quarter-wave plate 22, which is reflected by the mirror 21, and the beam splitters 14, 1/4. The light reaches the light receiving element 38 through the wave plate 36 and the astigmatism lens 37.

  Here, the reflected light from the quarter-wave plate 17 reaching the light receiving element 38 and the reflected light from the spherical aberration correcting element 23 are respectively on the optical axis connecting the center of the astigmatism lens 37 and the light receiving element 38. On the other hand, it is in a slightly inclined state. For this reason, the arrival position of these two reflected lights to the light receiving element 38 is shifted, but two lights are irradiated on substantially the same portion, and as a result, interference between the two lights occurs, In the element 38, when the relative position between the recording / reproducing lens 6 and the address detecting lens 5 is changed, light and dark stripes that change with time are formed.

  As described above, the number of layers in the recording medium 1 to be recorded or the number of layers to be read depends on how the distance between the recording / reproducing lens 6 and the recording medium 1 is set. It is important that the position of the recording / reproducing lens 6 can be set by counting the number of times of light intensity based on the change of the interference fringes that changes with time in the light receiving element 38 ( In this case, the position of the address detection lens 5 constitutes a reference point).

  Of course, the recording / reproducing lens 6 and the address detecting lens 5 are integrated as described above. Even when the recording / reproducing lens 6 is moved, the address detecting lens 5 correctly addresses 8. Must read.

  Therefore, the focus correction for reading the address 8 using the address detection lens 5 is performed using the electromagnetic coil 31 as described above.

  Now, after setting the number of layers of the recording medium 1 as described above, recording is performed in that layer in the state shown in FIG.

  In FIG. 5, address detection using the address detection lens 5 is not described in order to avoid complication of the drawing, but as is apparent from the above description, this address detection is performed for recording and reproduction. Address detection is performed using light of the same wavelength as the light source, specifically, light from the light source 9, so that even if the address 8 of the recording medium 1 is extremely dense, it can be read accurately. Can do.

  In this embodiment, the NA (numerical aperture) of the address detection lens 5 is set to 0.85, for example, which is larger than the NA (numerical aperture) 0.65 of the recording / reproducing lenses 6 and 7. The light having the wavelength as described above, specifically, the blue light from the light source 9 can be narrowed down to a smaller spot. As a result, even if the address 8 of the recording medium 1 is miniaturized, the small address 8 Can be reliably read using the address detecting lens 5.

  Therefore, as shown in FIG. 5, the recording performed in the multilayer recording on the recording medium 1 is very dense in each layer, so that the capacity can be increased accordingly.

  For example, if the information supplied to the light source 9 is for security, specifically, video from a surveillance camera, one year of security information is recorded on one recording medium 1. Can do. This can greatly contribute to the recent demands for improving security.

  In other words, security countermeasures using such a surveillance camera is a major hindrance to having to frequently change recording media, but it is possible to perform precise information recording as in this embodiment. Then, as described above, the security information for one year can be recorded on one recording medium 1, so that the complexity is eliminated and the contribution to the spread is greatly made.

  In this embodiment, address detection and recording / reproduction are performed by one light source 9, but address detection and recording / reproduction can be performed by separate light sources.

  However, even when address detection and recording / reproduction are performed using separate light sources, the wavelength of the address light source is the same as or shorter than the wavelength of the recording / reproduction light source. It is important to keep

  In other words, in order to perform precise information recording / reproduction, it is impossible to perform such precise information recording / reproduction without the same or more precise address information. It is important that the wavelength of the recording light is the same as that of the recording / reproducing light source or shorter than that of the recording / reproducing light source.

  FIG. 6 is a diagram illustrating reading of information recorded in a multilayer on the recording medium 1. At this time, reflected light from the recording / reproducing lens 7 is prevented from returning to the light receiving element 38. Specifically, at the time of this reproduction, the shutter 25 provided in front of the retro reflector 26 is closed so that the reflected light does not return through the recording / reproducing lens 7, and thereby noise components are mixed in the reproduction data. It was set as the structure which suppresses this.

  In addition to the method of closing the shutter 25, the recording / reproducing lens 7 disposed above the recording medium 1 can be used for recording / reproducing by driving the screw shaft 33 described with reference to FIGS. By moving the lens 6 to a position that does not face the lens 6, it is possible to prevent the reflected light from returning via the recording / reproducing lens 7. That is, if the recording / reproducing lens 6 and the recording / reproducing lens 7 are displaced in the radial direction of the recording medium 1, the reflected light can be prevented from returning through the recording / reproducing lens 7 without providing the shutter 25. This makes it possible to prevent noise components from being mixed into the reproduction data.

  FIG. 7 shows a state in which the CD 41 is mounted on the rotary drive shaft 4 instead of the recording medium 1, and recording or reproduction can be performed in this state.

  At this time, since the amount of information contained in the CD 41 is not so large, infrared light is emitted from the light source 39, and this is provided near the upper surface in the thickness direction of the CD 41 through the path of the arrow shown in FIG. The data 42 is written on the recorded surface, or the data 42 on the recorded surface is read.

  That is, the CD 41, the DVD shown in FIG. 8, and the BD (Blu-ray Disc) shown in FIG. 9 have address information in the data 42, so that address confirmation and writing or reading to the address can be performed simultaneously. It is. The read data at the time of reproduction is supplied to the light receiving element 38.

  FIG. 8 shows recording / reproduction on the DVD 43, which is different from the CD 41 in FIG. 7 in that red light is emitted from the light source 39 and data is recorded on the recording surface provided near the intermediate surface in the thickness direction of the DVD 43. 44 or writing the data 44 on the recording surface near the intermediate surface. Note that the writing of the data 44 to the DVD 43 and the detection of reading of the data 44 by the light receiving element 38 have the same path as the CD 41.

  FIG. 9 shows recording / reproduction of data 46 to / from the BD 45.

  At this time, the blue light emitted from the light source 9 is recorded on the recording surface provided near the lower surface in the thickness direction of the BD 45 through the address detection lens 5 as shown in FIG. .

  The recorded data 46 is read out through the address detecting lens 5 and detected through the address detecting element 20. That is, in the present embodiment, the information that can be recorded and read to and from the recording medium 1 capable of multi-layer recording can be recorded and reproduced on the CD 41, the DVD 43, and the BD 45.

  With the above description, when the configuration and operation of each part are understood, the greatest feature point in the present embodiment will be described with reference to FIGS.

  In the present embodiment, for example, 100 layers are recorded on the recording medium 1 capable of multi-layer recording as shown in FIGS.

  Specifically, this recording medium 1 has a disk shape as shown in FIG. 10, and data is stored in a total of 100 layers of 1A to 50A and 1B to 50B at predetermined intervals from the front surface to the back surface. As described above, the recording / reproducing lenses 6 and 7 are formed of interference fringes due to light interference at the light intersections, and constitute a part of the digital signal. The interference fringes are intermittently formed on one plane (in the inner layer) where the interference fringes are formed, whereby video and audio are recorded as digital signals.

  In the present embodiment, in such a situation, between the front and back surfaces of the recording medium 1, the recording layers 1 </ b> A to 50 </ b> A and 1 </ b> B to 50 </ b> B adjacent to each other in the front and back direction of the recording medium 1. Data of the recording layer, for example, the recording layer 1B in FIG. 11, the recording layer 1A on the upper side, and the recording layer 2A on the lower side are shifted in a direction orthogonal to the front and back surface direction of the recording medium 1.

  For this reason, when the recording medium 1 is viewed from the front surface side (upper surface side), the data of the recording layer 1A and the recording layer 1B are shifted in a direction orthogonal to the front and back surfaces of the recording medium 1 as shown in FIG. (This state is also expressed as a state where tracks on which data is recorded in the recording layer 1A and the recording layer 1B are shifted in a direction perpendicular to the front and back surfaces of the recording medium 1).

  Therefore, from the viewpoint of data reading, as shown in FIG. 11, one piece of data on the recording layer 2A is present at the beam waist portion of the light (the portion where the wavefront of the light is substantially parallel) by the recording / reproducing lens 6. As a result, only one piece of data can be read, and as a result, the reliability of reading is improved.

  In FIG. 11, since the intersection of the light advances from the front of the paper to the back of the paper, the data existing on the left and right of the light beam waist is adjacent to the recording layer 2A. Track data.

  Further, the data of the adjacent recording layer 1B and the recording layer 2B exist above and below the light beam waist. In these data portions, the wavefront of the light as shown in FIG. Since it reaches in an inclined state, it cannot be properly read by the recording / reproducing lens 6, and from this point, only one data existing in the beam waist portion of the light by the recording / reproducing lens 6 is appropriate. As a result, the reliability for reading is improved.

  FIG. 12 shows a comparative example of the present embodiment. In this example, the data of the recording layers 1a to 3a are overlapped in the vertical direction. That is, in order to increase the recording density in each of the recording layers 1a to 3a, the recording layers 1a to 3a are in a state where data is recorded.

  For this reason, there are three pieces of data of the recording layer 2a in the beam waist portion of the light by the recording / reproducing lens 6, and in this case, the data of the tracks on both sides are also read, so the reliability for reading is reduced. It becomes low.

  Therefore, in the comparative example shown in FIG. 12, it is considered that the data on both sides of the three data of the recording layer 2a existing in the beam waist portion of the light by the recording / reproducing lens 6 is thinned out. If it does so, the recording density of the recording medium 1 will fall.

  Therefore, in the present embodiment, the recording layers 1B to 50B are provided between the recording layers 1A to 50A, thereby preventing a decrease in the data amount.

  Furthermore, in this embodiment, the data in the recording medium 1 can be arranged three-dimensionally more efficiently than in the comparative example, so that the recording capacity of the recording medium 1 can be improved by optimizing the distance between tracks and the distance between recording layers. Can be increased as compared with the comparative example.

  In FIGS. 11 and 12, the recording layers 1 </ b> A, 1 </ b> B, 2 </ b> A, 2 </ b> B, and 3 </ b> A are equally described in the front and back direction (thickness direction) of the recording medium 1 in consideration of easy understanding. Actually, the recording layer 1A and the recording layer 1B, the recording layer 2A and the recording layer 2B... Are close to each other, and conversely, the recording layer 1B and the recording layer 2A, and the recording layer 2B and the recording layer. 3A... The recording layer 49 </ b> B and the recording layer 50 </ b> A are largely separated from each other, thereby suppressing an increase in recording layers provided in the recording medium 1.

  Even if the recording layer 1A and the recording layer 1B, the recording layer 2A and the recording layer 2B, and the recording layer 50A and the recording layer 50B are close to each other, the data of the recording layer 1A and the recording layer 1B are as shown in FIG. The recording medium 1 is shifted in a direction perpendicular to the front and back direction of the recording medium 1 (in this state, the tracks on which data is recorded in the recording layer 1A and the recording layer 1B are in the front and back direction of the recording medium 1). Therefore, as shown in FIG. 11, at the beam waist portion of the light by the recording / reproducing lens 6, there is only one data of the recording layer 2A. Therefore, only this one data can be read, and as a result, the reliability for reading is improved.

  Even if the recording layer 1A and the recording layer 1B, the recording layer 2A and the recording layer 2B, and the recording layer 50A and the recording layer 50B are close to each other, the recording layer 1A and the recording layer 1B (hereinafter referred to as recording layer 2A) It is preferable to prevent the data between the recording layers 2B... Between the recording layers 50A and 50B) from overlapping in the front and back direction (thickness direction) of the recording medium 1.

  In the above description, data reading, that is, reproduction has been described. However, for the same reason at the time of recording, this recording can also be performed appropriately and reliability is high.

  That is, even during this recording, only one data recording is performed at the intersection of light by the recording / reproducing lenses 6 and 7, so that the recording is performed appropriately and the reliability of the recording is high. .

  As described above, since the recording / reproducing apparatus of the present invention can improve the reliability with respect to the multi-layer recording, it can be widely used in various fields that require a large recording capacity. In addition, if the recording and reproduction can be performed precisely and with a large capacity, there is no need to replace the recording medium, and it becomes extremely convenient.

1 is a block diagram of a recording / reproducing apparatus according to an embodiment of the present invention. Enlarged view of the main part (A) Enlarged perspective view of the main part (b) Enlarged plan view of the main part Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Plan view of recording medium for explaining the operation Enlarged sectional view of the recording medium for explaining the operation An enlarged sectional view of a comparative example used for explaining the operation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium 1A Recording layer 1B Recording layer 2A Recording layer 2B Recording layer 3A Recording layer 2 Through-hole 3 Motor 4 Rotation drive shaft 5 Address detection lens 6 Recording / reproducing lens 7 Recording / reproducing lens 8 Address 9 Light source 10 Relay lens 11 Beam splitter 12 Collimator lens 13 1/2 wavelength plate 14 Beam splitter 15 1/4 wavelength plate 16 Beam splitter 17 1/4 wavelength plate 18 Hologram 19 Astigmatism lens 20 Address detection element 21 Mirror 22 1/4 Wave plate 23 Spherical surface Aberration correction element 24 Spherical aberration correction element 25 Shutter 26 Retro reflector 27 Frame 28 Screw shaft 29 Motor 30 Electromagnetic coil 31 Electromagnetic coil 32 Electromagnetic coil 33 Screw shaft 34 Motor 35 Electromagnetic coil 36 1/4 wavelength plate 37 Astigmatism lens 38 Light receiving element 39 Light source 40 Diffraction grating 41 CD
42 Data 43 DVD
44 data 45 BD
46 data

Claims (12)

Rotation drive means for rotating a recording medium capable of multilayer recording;
A recording / playback lens and an address detection lens disposed opposite to the recording medium rotated by the rotation driving means;
A recording / reproducing light source for supplying recording / reproducing light to the recording / reproducing lens;
An address light source for supplying address light to the address detection lens;
Among a plurality of recording layers provided at a predetermined interval between the front and back surfaces of the recording medium, the data of the recording layer adjacent in the front and back direction of the recording medium is set in a direction orthogonal to the front and back surface direction of the recording medium. Shifted recording / playback device. Among a plurality of recording layers provided at predetermined intervals in the front and back direction of the recording medium, the data tracks of the recording layers adjacent in the front and back direction of the recording medium are orthogonal to the front and back direction of the recording medium. The recording / reproducing apparatus according to claim 1, which is shifted. The recording / reproducing apparatus according to claim 1, wherein the address light source is a blue light source. 4. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing light source and the addressing light source are shared. 5. The recording / reproducing apparatus according to claim 1, wherein the NA (numerical aperture) of the address detection lens is larger than the NA (numerical aperture) of the recording / reproducing lens. The recording / reproducing lens includes a first recording / reproducing lens provided on the address detection lens side of the recording medium, and a second recording / reproducing lens disposed opposite to the first recording / reproducing lens via the recording medium. 6. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus is a lens. 7. The recording / reproducing apparatus according to claim 1, wherein the address detecting lens and the recording / reproducing lens are arranged side by side upstream and downstream of the track-like address of the recording medium. 8. The recording / reproducing apparatus according to claim 1, wherein the address detecting lens is disposed upstream of the recording / reproducing lens with respect to the rotation direction of the recording medium. 9. The recording / reproducing apparatus according to claim 1, wherein the address detection lens and the recording / reproducing lens have means for varying a distance from one side of the recording medium. The recording / reproducing apparatus according to claim 6, wherein the recording / reproducing lens is optically connected to a light receiving element for detecting a defocus of the first recording / reproducing lens and the second recording / reproducing lens. 11. The recording / reproducing apparatus according to claim 1, wherein security information is supplied to the recording / reproducing light source. A disc-shaped recording medium, of the plurality of recording layers provided at a predetermined interval between the front and back surfaces of the disc-shaped recording medium, the data of the recording layers adjacent in the front-back direction are Recording media shifted in the direction orthogonal to the front and back direction.

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