JP2010055712A - Recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize reproduction of multi-layer recording, with respect to a recording and reproducing device. <P>SOLUTION: The recording and reproducing device includes: a rotary drive means (motor) for rotation-driving of a recording medium 1 being multi-layers recordable; lenses 6, 7 for recording and reproducing arranged oppositely to the recording medium 1 rotation-driven by this rotation-drive means, a lens 5 for address detection arranged oppositely to the recording medium 1; a light source 39 for recording and reproducing, for supplying light for recording and reproducing to the lenses 6, 7 for recording and reproducing; and a light source 9 for address for supplying light for address to the lens 5 for address detection, and constituted so that recording for the recording medium 1 is performed by forming interference fringes wherein the reference light made incident on this recording medium 1 through the lens 6 for recording and reproducing is interfered with the recording light made incident on this recording medium 1 through the lens 7 for recording and reproducing, and wherein multi-layer recording for the recording medium 1 are performed successively toward the recording light incident side from the reference light incident side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording / reproducing apparatus that performs recording and reproduction on a recording medium capable of multilayer recording.

  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, a conventional recording / reproducing apparatus includes a rotation driving unit that rotationally drives a recording medium capable of multi-layer recording, a lens that is opposed to the recording medium that is rotationally driven by the rotation driving unit, and a recording / reproducing light on the lens. The recording / reproducing light source for supplying the light 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 conventional recording / reproducing apparatus, recording on the medium is performed by causing the reference light incident on the recording medium through the recording / reproducing lens and the recording light to interfere with each other, thereby forming interference fringes in the recording medium. It was the structure performed by forming.

  The problem in the conventional example as described above is that the operation becomes unstable when the recording medium is reproduced.

  That is, in the conventional example, when trying to perform multilayer recording in a recording medium, it is considered that multilayer recording is sequentially performed on the recording medium from the recording light side (for example, the upper surface side) toward the reference light side (for example, the lower surface side). It was.

  However, even in such a case, at the time of reproduction, the recording of each layer is read from the reference light side (for example, the lower surface side), so this reading becomes unstable.

  This point will be specifically described below.

  When performing multilayer recording sequentially from the recording light side (for example, the upper surface side) toward the reference light side (for example, the lower surface side), if attention is paid to the reference light incident on the recording medium, the recording medium is directed to an interference point with the recording light. There is no existing interference fringe in the optical path of the reference light.

  However, when reading information from multiple layers of the recording medium, for example, the 10th layer from the bottom during playback, there are interference fringes from the 1st to 9th layers below it in the optical path of the reference light. Since the state of the optical path is too different between recording and reproduction, as described above, this reading is unstable and reproduction is unstable.

  Accordingly, the object of the present invention is to stabilize reproduction.

  In order to achieve this object, the present invention comprises a rotation driving means for rotationally driving a recording medium capable of multilayer recording, a recording / reproducing lens disposed opposite to the recording medium rotated by the rotation driving means, An address detection lens disposed opposite to a recording medium, a recording / reproducing light source for supplying recording / reproducing light to the recording / reproducing lens, and an address light source for supplying address light to the address detecting lens Recording on a medium is performed by a recording / reproducing apparatus configured to cause interference between the reference light incident on the recording medium via the recording / reproducing lens and the recording light to form interference fringes. Multi-layer recording is performed sequentially from the reference light incident side to the recording light incident side, thereby achieving the initial purpose.

  As described above, the present invention has a configuration in which recording on the recording medium is performed by causing the recording light to interfere with the reference light incident on the recording medium via the recording / reproducing lens to form interference fringes. In the recording / reproducing apparatus, the multilayer recording on the recording medium is sequentially performed from the reference light incident side to the recording light incident side, so that the reproduction can be stabilized.

  That is, in the present invention, multilayer recording is performed sequentially from the reference light side (for example, the lower surface side) to the recording light side (for example, the upper surface side). For example, when recording from the bottom to the tenth layer, Focusing on the reference light incident on the recording medium, there are 1 to 9 layers of interference fringes from the bottom recorded earlier in the optical path of the reference light toward the interference point with the recording light in the recording medium. Become.

  However, for example, when reproducing information from the 10th layer from the bottom, interference fringes from the 1st to 9th layers below exist in the optical path of the reference light in the same way as at the time of recording. From the viewpoint of light, since the state of the optical path is exactly the same during recording and during reproduction, this reading can be performed stably, and as a result, reproduction is stabilized.

  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. Opposite to the one surface side of the media 1, they are arranged side by side in the proximity state.

  Of course, the address detection lens 5 and the recording / reproducing lens 6 are separate and independent, and the address detecting lens 5 has a configuration suitable for address detection, and the recording / reproducing lens. 6 has a configuration suitable for multilayer recording and reproduction.

  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, which constitute a part of the digital signal.

  Then, the interference fringes are intermittently formed on one plane (inside the 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, the intersections of the light by the recording and reproducing lenses 6 and 7 are moved by moving them to a plurality of recording surfaces in the thickness direction of the recording medium 1. In addition, since the video and audio are recorded as digital signals on one plane and can be formed in a plurality of layers in the thickness direction of the recording medium 1, the recording capacity of the recording medium 1 may be extremely large. It can be done.

  Further, as a major feature of the present embodiment, when multilayer recording is performed in the thickness direction of the recording medium 1, recording is sequentially performed from the lower side to the upper side in FIG.

  In this case, the light emitted from the recording / reproducing lens 6 to the recording medium 1 is referred to as reference light, and the light emitted to the recording medium 1 through the recording / reproducing lens 7 after being reflected by the retroreflector 26 is recorded. It is called light.

  Therefore, in other words, when multilayer recording is performed in the thickness direction of the recording medium 1, recording is performed sequentially from the incident side of the reference light toward the incident side of the recording light as shown in FIG. It is a feature.

  If the recording capacity of the recording medium 1 is increased, for example, if security information of the surveillance camera is recorded on the recording medium 1, it is possible to record one year on the recording medium 1. It will be understood that this makes the recording capacity extremely large.

  The address detection lens 5 is provided to perform multilayer recording using the recording / reproducing lenses 6 and 7 described above and 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.

  Further, the position where the address detection lens 5 appropriately reads the address 8 of the recording medium 1 becomes the reference position of the address detection lens 5, and the position of the recording / reproducing lens 6 is controlled based on this reference position. It has become so.

  The reason why the address detecting lens 5 having such a role is provided separately from the recording / reproducing lens 6 is to appropriately read the address 8 provided on the lower surface side of the recording medium 1. is there.

  That is, when the address 8 is subdivided in order to increase the recording density, in order to read the address 8 of the subdivided recording medium 1, it is better to provide the address detection lens 5 dedicated to address reading. It is easy to increase the reliability of the operation.

  Since recording / reproduction to / from the recording medium 1 is performed based on the segmented address information, the recording density is increased and the capacity can be increased.

  Further, since the recording / reproducing light is supplied to the recording medium 1 through the recording / reproducing lenses 6 and 7, and the address light is supplied to the recording medium 1 through the address detecting lens 5, recording is performed. Interference between the recording / reproducing light and the address light in the medium 1 hardly occurs, and as a result, the address detection via the address detecting lens 5 and the recording medium via the recording / reproducing lenses 6 and 7 are applied. Recording and playback operations are stabilized.

  Next, the light source and the like for performing multi-layer recording using these recording / reproducing lenses 6 and 7 and subsequent reproduction and reading an address using the address detecting lens 5 will be described with reference back to FIG. .

  In the present embodiment, address reading using the address detection lens 5 is performed by address light from the light source 9. Further, multilayer recording on the recording medium 1 using the recording / reproducing lenses 6 and 7 and subsequent reproduction are performed by recording / reproducing light from the light source 39.

  In the present embodiment, a laser emitting blue light having a wavelength of 405 nm is used as the light source 9 (green light is also possible).

  The blue light from the light source 9 is first corrected to be enlarged in diameter and rounded by the relay lens 10, and then has a function of reflecting the beam splitter 11 (blue light passes, red light, and infrared light reflect). The collimator lens 12 then changes the light into parallel light. The parallel light passes one after another through the beam splitter 14, the beam splitter 16, and the quarter wavelength plate 17, and then passes through the address detection lens 5 and is condensed to the address 8.

  When the address 8 of the recording medium 1 is irradiated with blue light from the light source 9, reflection occurs at the address 8, and this reflected light is detected as address information.

  Specifically, the reflected light from the address 8 enters the beam splitter 16 after passing through the address detection lens 5 and then the quarter wavelength plate 17. By passing through the quarter-wave plate 17 twice in the path up to this point, it becomes S deflection, and as a result, it is reflected by the beam splitter 16 by 90 degrees, and this reflected light passes through the hologram 18 and becomes astigmatism. The light is collected by the aberration lens 19, and the collected light reaches the address detection element 20.

  Then, the address information is detected based on the information that has reached the address detection element 20, and based on this address information, the above-described recording / reproducing lenses 6 and 7 perform multilayer recording and subsequent reproduction.

  Further, the focus information of the address detection lens 5 with respect to the address 8 of the recording medium 1 is also detected based on the information reaching the address detection element 20.

  In other words, the position of the address detection lens 5 is adjusted so that the light reaching the address detection element 20 is focused on the address detection element 20, and this becomes the reference position, and the recording / reproduction lenses 6 and 7. Position control is 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. In this embodiment, the P-polarized light of the blue light from the light source 9 passes through the beam splitter 16 and the S-polarized light is reflected by the beam splitter 16 (note that the beam splitter 16 is light from a light source 39 described later. Is not reflected).

  That is, the P-polarized light emitted from the light source 9 and passed through the beam splitters 14 and 16 passes through the quarter wavelength plate 17 twice and becomes S-polarized light. It goes to the detection element 20.

  Thus, in this embodiment, the traveling direction of the addressing light can be changed by using the beam splitter 16 that separates the light according to the rotation direction of the circularly polarized light.

  In the present embodiment, as described above, recording / reproduction from the light source 39 is performed based on the address information detected by the address detection element 20 and the focus information of the address detection lens 5 with respect to the address 8 of the recording medium 1. Multi-layer recording using recording light and recording / reproducing lenses 6 and 7 and subsequent reproduction are performed.

  Specifically, the light source 39 is a light source that selectively emits red light having a wavelength of 650 nm and infrared light having a wavelength of 785 nm. Such a light source 39 that selectively emits red light of 650 nm and infrared light of 785 nm is still available as a commercial product at a low cost, and the specific frequency (wavelength is 650 nm or 785 nm). ) With a concentrated peak.

  The light source 39 is also used for recording and reproduction with respect to a DVD described later. When performing recording and reproduction on a DVD, a superimposing circuit is provided in a circuit for supplying power to the light source 39, and the electric signal for causing the light source 39 to emit light is superimposed so that red light emitted from the light source 39 is emitted. Is a mountain-shaped characteristic including other wavelengths (frequencies) other than 650 nm.

  Therefore, as shown in FIG. 1, when this light source 39 is used as light for recording / reproducing for multi-layer recording on a multi-recordable recording medium 1 and subsequent reproduction, a superimposing circuit for supplying power to the light source 39 The red light having a peak concentrated at a specific frequency (wavelength is 650 nm) can be easily obtained from the light source 39 by simply removing the superimposing circuit from the circuit that supplies power to the light source 39. It can be made to emit.

  Then, red light having a peak concentrated at a specific frequency (wavelength is 650 nm) is emitted from the light source 39 as shown in FIG. 1 and passes through the half-wave plate 13 and is orthogonal to each other. It is converted into light having polarization components (P-polarized light and S-polarized light).

  Then, light having two polarization components orthogonal to each other (P-polarized light and S-polarized light) passes through the diffraction grating 40 and enters the beam splitter 11, where (P-polarized light and S-polarized light) are also reflected by 90 degrees, The lens 12 changes the light into parallel light (that is, the beam splitter 11 can reflect both P-polarized light and S-polarized light of red light).

  Now, the S-polarized light of the parallel light after passing through the collimator lens 12 is reflected by the beam splitter 14 at a right angle to the left side of FIG. 1, and then reflected by the mirror 21 at a right angle again. After passing through the quarter-wave plate 22 and the spherical aberration correction element 23 one after another, the light is condensed in the recording medium 1 by the recording / reproducing lens 6 and then expanded from its focal point, and then the recording / reproducing lens. 7 is converted back to parallel light.

  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.

  At this time, as described above, since the light source 39 emits red light having a peak concentrated at a specific frequency (wavelength is 650 nm), the interference fringes can be made extremely clear.

  The recording / reproducing light is supplied to the recording medium 1 via the recording / reproducing lens 6, and the address light is supplied to the recording medium 1 via the address detecting lens 5. Therefore, a horizontal distance is formed between the two, and as a result, interference between the recording / reproducing light and the addressing light in the recording medium 1 hardly occurs. As a result, the address detecting lens 5 is Thus, the address detection via the recording medium and the recording / reproducing operations on the recording medium 1 via the recording / reproducing lenses 6 and 7 become stable.

  At this time, the address light from the address light source 9 is blue (or green) and the recording / reproduction light from the recording / reproduction light source 39 is red. Address detection and recording / reproducing operations on the recording medium 1 via the recording / reproducing lenses 6 and 7 can be further stabilized.

  That is, since the address detection lens 5 and the recording / reproducing lenses 6 and 7 are close to each other, the leaked light may reach each lens or the address part or the recording part in the recording medium 1. Since the address light from the light source 9 is blue (or green) and the recording / reproducing light from the recording / reproducing light source 39 is red, the recording / reproducing light in each lens unit and the recording medium 1 Interference with the address light hardly occurs, and as a result, the address detection via the address detection lens 5 and the recording and reproduction operations on the recording medium 1 via the recording and reproduction lenses 6 and 7 are stabilized. It becomes a thing.

  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 respect to the recording medium 1 in order to appropriately read the address 8 of the recording medium 1 by the address detection element 20, and the recording / reproducing lens 6, 7 requires that the focal points of the recording medium are correctly formed on the set recording surface portion, and these recording / reproducing lenses 6 and 7 need to perform multilayer recording in the thickness direction of the recording medium 1. Therefore, the drive control is important.

  Prior to this description, the address detection element 20 determines whether the information from the address 8 of the recording medium 1 is supplied via the astigmatism lens 19, and the address detection lens for the address 8 of the recording medium 1. The focus of 5 is determined. Then, the following adjustment is performed in order to focus the address detection lens 5 on the address 8 of the recording medium 1.

  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 quarter wavelength plate 22 and the spherical aberration correction element 23 are also used for the recording / reproducing lens. 6 and held at a constant interval.

  For this reason, in the present embodiment, the position information of the address detection lens 5 with respect to the recording medium 1 and the recording using the quarter wavelength plate 17, the quarter wavelength plate 22, and the spherical aberration correction element 23. The position information of the reproduction lens 6 is obtained.

  In this embodiment, the address detection lens 5 and the recording / reproducing lens 6 are arranged in the frame 27 along the upstream and downstream sides of the track-like address of the recording medium 1. In some cases, the recording / reproducing lens 6 is arranged in the frame 27 along the radial direction of the recording medium 1.

  As described above, in the present embodiment, the frame 27, the screw shaft 28, and the motor 29 constitute the frame driving means for moving the frame 27 in the radial direction of the recording medium 1, so that the address can be obtained only by moving the frame 27. The detection lens 5 and the recording / reproducing lens 6 can be moved together. Therefore, the operation is fast, and the relationship between the address detection lens 5 and the recording / reproducing lens 6 can be easily kept constant.

  This leads to the fact that the adjustment amount can be reduced when adjusting the recording / reproducing lens 6 based on the position of the address detection lens 5 as in the present embodiment, resulting in faster operation, Stability is also increased.

  In other words, in the present embodiment, the address detection lens 5 is arranged on the upstream side of the rotation of the recording medium 1 relative to the recording / reproducing lens 6 in the frame 27. In this state, electromagnetic coils 30 for adjusting the distances between the address detection lens 5, the recording / reproducing lens 6 and the recording medium 1 are provided at the four corners of the frame 27.

  That is, the electromagnetic coil 30 has the positional information of the address detection lens 5 with respect to the address 8 of the recording medium 1 detected by the address detection element 20 with respect to the distance between the address detection lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1. Therefore, the lens distance adjusting means for adjusting is used. At this time, since the address detection lens 5 and the recording / reproducing lens 6 are unitized in the frame 27, the adjustment of the address detecting lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1 can be performed in a short time. It can be done stably.

  Further, the position of the address detection lens 5 with respect to the address 8 of the recording medium 1 detected by the address detection element 20 by fine adjustment of the individual distances of the address detection lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1. In order to adjust based on the information, electromagnetic coils 31 and 32 are provided at the four corners of the address detecting lens 5 and the recording / reproducing lens 6, respectively.

  That is, these electromagnetic coils 31 and 32 are also lens distance adjusting means for adjusting the distance between the address detecting lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1.

  It should be noted that the arrangement of the address detection lens 5 and the recording / reproducing lens 6 in a balanced manner on the left and right sides in the frame 27 also allows the frame 27 to move smoothly and increases stability against vibration. Become.

  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. The screw shaft 33 and the motor 34 constitute driving means for moving the recording / reproducing lens 7 in the radial direction of the recording medium 1.

  Further, in order to adjust the distance of the recording / reproducing lens 7 with respect to the recording medium 1, an electromagnetic coil 35 is provided, and this electromagnetic coil 35 constitutes a lens distance adjusting means.

  Further, the recording / reproducing lens 6 and the address detecting lens 5 in the frame 27 are provided with lens position correcting means for adjusting the position in the frame 27, respectively.

  Specifically, as shown in FIG. 3B, the recording / reproducing lens 6 and the address detecting lens 5 are provided in the frame 27. As described in FIG. A portion of the frame 27 surrounding the outer periphery of the recording / reproducing lens 6 and the address detecting lens 5 is a square frame (rectangular frame). Capacitor electrodes are respectively provided on the four orthogonal inner peripheral surfaces of the square frame. (Not shown) is arranged.

  In addition, the outer shape of the recording / reproducing lens 6 and the address detecting lens 5 arranged at predetermined intervals in the square frame of the frame 27 is also a square shape. Capacitor electrodes (not shown) are also arranged on the four square outer peripheral surfaces of the lens 5.

  That is, four capacitors are formed on the outer peripheral surfaces of the recording / reproducing lens 6 and the address detecting lens 5.

  Therefore, if the capacitances of the capacitors on the outer peripheral four surfaces of the recording / reproducing lens 6 and the address detecting lens 5 are detected, the positional relationship between the recording / reproducing lens 6 and the address detecting lens 5 within the square frame of the frame 27 is detected. Can be determined.

  Based on this discrimination information, an electromagnetic coil (not shown) is energized to correct the positional relationship between the recording / reproducing lens 6 and the address detecting lens 5 within the square frame of the frame 27. That is, the lens position correcting means is constituted by the capacitor electrode (not shown) and the electromagnetic coil (not shown) in this portion.

  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, 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 transmitted to the recording / reproducing lens 6, then the spherical aberration correcting element 23, the quarter wavelength plate 22, then the mirror 21, and the beam splitter. 14, and then passes through the quarter-wave plate 36 and the astigmatism lens 37, and then is detected by the light receiving element 38.

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

  Also in this case, the position information of the recording / reproducing lens 6 is based on the position information of the address detecting lens 5, and the recording / reproducing lens 6 is always based on the position information of the address detecting lens 5. , 7 focus control is performed.

  Next, the response speed when the recording medium 1 is vibrated will be described.

  That is, the vibration of the recording medium 1 is generated when external kinetic energy (impact) is applied to the recording medium 1 or when the recording medium 1 itself is slightly curved from the horizontal state (surface wavy state). Even in this case, in this embodiment, the address 8 of the recording medium 1 is first read to continue the recording and reproducing operation.

  That is, in the present embodiment, as described above, the position information of the address detection lens 5 is used as a reference, and the focus control of the recording / reproducing lenses 6 and 7 is always performed using the position information of the address detection lens 5 as a reference. Is to be done.

  For this reason, even when the vibration of the recording medium 1 occurs, first, the focus information of the address detection lens 5 with respect to the address 8 of the recording medium 1 is detected based on the information reaching the address detecting element 20.

  The focus information is first transmitted to a circuit that drives the electromagnetic coil 30 in FIG. 3, thereby roughly adjusting the distance between the address detection lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1 together with the frame 27. Do.

  That is, in the present embodiment, the address detection lens 5 and the recording / reproducing lens 6 are unitized in the frame 27, so that rough adjustment of the address detecting lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1 is shortened. It can be done stably in time.

  Further, the fine adjustment of the individual distances of the address detecting lens 5 and the recording / reproducing lens 6 with respect to the recording medium 1 is performed by the position of the address detecting lens 5 with respect to the address 8 of the recording medium 1 detected by the address detecting element 20. This is performed by energizing the electromagnetic coils 31 and 32 provided at the four corners of the address detecting lens 5 and the recording / reproducing lens 6 based on the information.

  Here, in the present embodiment, the focus adjustment information by the electromagnetic coil 31 (first focus adjustment means) for the address detection lens 5, that is, the current direction and the current magnitude are finely adjusted. Before completion, the control information is supplied in advance to a circuit that drives an electromagnetic coil 32 (second focus adjusting means) that performs focus adjustment of the recording / reproducing lens 6.

  In other words, on the recording / reproducing lens 6 side (the circuit that drives the electromagnetic coil 32), it is notified in which direction and how much adjustment is necessary before the position adjustment of the address detecting lens 5 is completed. Therefore, the adjustment can be started as soon as possible.

  For this reason, even if the recording medium 1 is vibrated, an appropriate distance adjustment can be made in accordance with the recording medium 1 that vibrates the address detection lens 5 and the recording / reproducing lenses 6 and 7. It is possible to increase the reliability of

  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 FIG.

  In this case, as described above, the position of the address detection lens 5 and the position of the recording / reproducing lens 6 are determined and set.

  After that, the number of layers of the recording medium 1 to be recorded or the number of layers from which recording 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 39 goes straight to the beam splitter 16 as indicated by a broken line, and then is reflected on the back surface side of the quarter-wave plate 17. After being reciprocated through the / 4 wavelength plate 17, it is changed to S-polarized light, then passes through the beam splitter 16, is then reflected 90 degrees at the beam splitter 14, and then subjected to circular deflection at the ¼ wavelength plate 36, It goes to the light receiving element 38.

  On the other hand, the S-polarized light traveling from the light source 39 to the beam splitter 14 is reflected toward the mirror 21 and travels toward the recording / reproducing lens 6 as shown in FIG. However, a part of the light traveling from the mirror 21 toward the recording / reproducing lens 6 is reflected on the back surface side (spherical aberration correction element 23 surface side) of the quarter-wave plate 22 and proceeds to the mirror 21. At this time, a part of the reflected light as shown by the broken line passes through the quarter-wave plate 22 to be P-polarized, so that the light traveling from the mirror 21 toward the beam splitter 14 passes through the beam splitter 14. Then, after being subjected to circular deflection by the quarter wavelength plate 36, it goes to the light receiving element 38.

  Here, the reflected light from the back surface side of the quarter wavelength plate 17 reaching the light receiving element 38 and the reflected light from the back surface side of the quarter wavelength plate 22 (the front surface side of the spherical aberration correction element 23) are: Each is slightly inclined with respect to the optical axis connecting the center of the astigmatism lens 37 and the light receiving element 38. 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 by using the frame 27 as described above. Even when the recording / reproducing lens 6 is moved, the address detecting lens is used. 5 must read address 8 correctly.

  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 by blue light from the light source 9. Since the address is detected by irradiating light to the address 8 using the lens 5 for address detection, even if the address 8 of the recording medium 1 is extremely high in density, it is accurately detected. It can be read by the element 20.

  Therefore, as shown in FIG. 5, the multi-layer recording into the recording medium 1 performed by the red recording / reproducing light from the light source 39 is very dense in each layer, and the capacity can be increased accordingly. .

  For example, if the information supplied to the light source 39 is for security, specifically, video from a surveillance camera, the security information for one year 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.

  Although the address light source 9 is blue, it may be green. What is important is that the address light source 9 has a shorter light wavelength than the recording / reproducing light (red) light source 39.

  In other words, in order to perform detailed information recording / reproduction, if there is no more detailed address information, it is impossible to perform such detailed information recording / reproduction. The light wavelength is shorter than the light source 39 of the recording / reproducing light.

  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.

  As described above, in the present embodiment, recording and reproduction on the recording medium 1 are performed extremely stably. For this reason, as described above, as a major feature of the present embodiment, the recording medium 1 When multilayer recording is performed in the thickness direction, recording is sequentially performed from the lower side to the upper side in FIG.

  The light emitted from the recording / reproducing lens 6 to the recording medium 1 is called reference light, and the light emitted to the recording medium 1 through the recording / reproducing lens 7 after being reflected by the retroreflector 26 is called recording light. Therefore, in other words, when performing multi-layer recording in the thickness direction of the recording medium 1, as a major feature of the present embodiment, the reference light incident side is directed to the recording light incident side as shown in FIG. Are recorded sequentially.

  Next, the effect of recording sequentially from the reference light incident side to the recording light incident side will be described.

  FIG. 10A shows the embodiment of the present invention, in which multilayer recording is sequentially performed from the reference light side (recording / reproducing lens 6 side) to the recording light side (recording / reproducing lens 7 side). It is.

  FIG. 10B shows a comparative example for the present invention, in which multilayer recording is sequentially performed from the recording light side (recording / reproducing lens 7 side) to the reference light side (recording / reproducing lens 6 side). .

  First, the problem of the comparative example will be described with reference to FIG.

  As shown in FIG. 10B, when sequentially performing multilayer recording from the recording light side (recording / reproducing lens 7 side) to the reference light side (recording / reproducing lens 6 side), interference occurs when viewed from the reference light. At the fringe formation point, recording on each layer is performed in a state where the existing interference fringes 15 do not exist.

  However, at the time of reproduction after recording is completed, only the reference light is incident on the recording medium 1 and the interference fringes 15 are read as one of the digital data. 1 to 9 layers of interference fringes 15 exist from below, and in this situation, the tenth interference fringe 15 from the bottom must be read.

  That is, for the reference light at the time of reproduction, even when reading the interference fringes 15 of the same layer, this reading must be performed in a state different from that at the time of writing. It becomes unstable.

  On the other hand, in the embodiment of the present invention shown in FIG. 10A, multilayer recording is sequentially performed from the reference light side (recording / reproducing lens 6 side) to the recording light side (recording / reproducing lens 7 side). Therefore, when viewed from the reference light, the state at the interference fringe formation point is the same during recording and during reproduction.

  For example, in the case of recording on the tenth layer from the bottom, when attention is paid to the reference light incident on the recording medium 1, the optical path of the reference light toward the interference point with the recording light in the recording medium 1 is first recorded. There will be 1 to 9 layers of interference fringes 15 from the bottom.

  Next, for example, even when reproducing information from the tenth layer from the bottom, the interference fringes 15 from the first to ninth layers below exist in the optical path of the reference light. As can be seen, since the state of the optical path is exactly the same during recording and during reproduction, this reading can be performed stably, and as a result, reproduction is stabilized.

  This is the greatest characteristic point in the present embodiment. In order to further enhance the effect, the present embodiment is configured to write a write completion signal on the recording medium 1 for each recording surface.

  That is, as described above, in order to make the optical path state exactly the same at the time of recording and at the time of reproduction when viewed from the reference light, recording is performed on a layer above it (for example, the second layer on the recording / reproducing lens 7 side). When switching surfaces, the writing completion signal is written in the first layer.

  The reason for this is that, for example, when recording is performed after switching to the second layer while the first layer recording area is still vacant, and the recording area is recorded again after recognizing that the first layer recording area is vacant. From the viewpoint of the reference light, the second layer interference fringe 15 overlapped with the first-layer recording portion recorded later is viewed from the reference light even if the optical path state is made to be exactly the same during recording and reproduction. The state of the optical path is different between recording and reproduction.

  Therefore, in the present embodiment, the recording medium 1 is configured to write a write completion signal for each recording surface, and in this way, when viewed from the reference light, during recording and during reproduction, Since the state of the optical path is exactly the same, this reading can be performed stably, and as a result, the reproduction is stabilized.

  Note that the recording / reproducing light supplied from the same light source 9 as the addressing light has the same effect.

  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 (785 nm) is emitted from the light source 39 and passes through the path indicated by the arrow shown in FIG. The data 42 is written on the recording surface provided on the recording surface, or the data 42 on the recording 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. Further, as a standard peculiar to the DVD 43, there is a point provided with a diffraction grating 40 for separating red light from the light source 39 into three, but since this is a well-known technique, description thereof is omitted.

  In addition, the writing of data 44 to the DVD 43 and the reading detection of the data 44 by the light receiving element 38 are also the same route as the CD 41, and this is also a well-known technique, so the description is omitted.

  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.

  In other words, in the present embodiment, the information can be recorded and read out on the recording medium 1 capable of multi-layer recording, but the recording medium can be recorded and reproduced on the CD 41, the DVD 43, and the BD 45.

  As described above, the recording / reproducing apparatus of the present invention performs extremely dense and large-capacity information recording and can reproduce the information, and has high operational stability. It will be widely used in various fields where a large capacity of recording is required. 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 (A) Block diagram showing this embodiment (b) Block diagram showing a comparative example with respect to this embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium 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 Interference fringes 16 Beam splitter 17 1/4 wavelength plate 18 Hologram 19 Astigmatism lens 20 Address detection element 21 Mirror 22 1/4 wavelength plate 23 Spherical aberration correction element 24 Spherical aberration correction element 25 Shutter 26 Retro reflector 27 Frame 28 Screw shaft DESCRIPTION OF SYMBOLS 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 (15)

Rotation drive means for rotating a recording medium capable of multilayer recording;
A recording / reproducing lens disposed opposite to the recording medium rotated by the rotation driving means;
An address detection lens disposed opposite to the recording medium;
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;
In the recording / reproducing apparatus configured to perform recording on the recording medium by causing the recording light to interfere with the reference light incident on the recording medium via the recording / reproducing lens, and forming interference fringes,
A recording / reproducing apparatus configured to sequentially perform multilayer recording on the recording medium from a reference light incident side to a recording light incident side. 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. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus is configured by a lens, the first recording / reproducing lens is for reference light incidence, and the second recording / reproducing lens is for recording light incidence. The recording / reproducing apparatus according to claim 2, wherein the first recording / reproducing lens and the address detecting lens are unitized. 4. The recording / reproducing apparatus according to claim 3, wherein the first recording / reproducing lens and the address detecting lens are provided in the frame. 5. The recording / reproducing apparatus according to claim 4, wherein the frame is provided with frame driving means for moving the frame in a radial direction of the recording medium. 6. The first recording / reproducing lens, the second recording / reproducing lens, and the address detecting lens are provided with lens distance adjusting means for adjusting the distance of each lens to the recording medium. The recording / reproducing apparatus as described in one. 7. The recording / reproducing apparatus according to claim 4, wherein the first recording / reproducing lens and the address detecting lens in the frame are each provided with lens position correcting means for adjusting the position in the frame. 8. The recording / reproducing apparatus according to claim 7, wherein the lens position correcting means is configured to correct the lens position in the frame by changing the capacitance of a capacitor formed between the lens and the frame. 9. The outer periphery of the first recording / reproducing lens and the address detection lens in the frame is provided with a rectangular frame surrounding the outer periphery of each lens, and capacitor electrodes are arranged on four orthogonal surfaces of each rectangular frame. The recording / reproducing apparatus as described. 10. The recording / reproducing apparatus according to claim 4, wherein the address detecting lens and the first recording / reproducing lens are arranged in a frame side by side upstream and downstream of the track-like address of the recording medium. 10. The recording / reproducing apparatus according to claim 4, wherein the address detecting lens and the first recording / reproducing lens are arranged in a frame side by side in a radial direction of the recording medium. The recording / reproducing lens according to any one of claims 2 to 11, wherein the recording / reproducing lens is optically connected to a light receiving element that detects a defocus between the first recording / reproducing lens and the second recording / reproducing lens. Playback device. The recording / reproducing apparatus according to claim 1, wherein a writing completion signal is written to the recording medium for each recording surface. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing light source and the addressing light source are shared. 15. The recording / reproducing apparatus according to claim 1, wherein security information is supplied to the recording / reproducing light source.

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