JP4395725B2 - Optical recording / reproducing apparatus and method - Google Patents

Description

  The present invention relates to a focus and tracking control method suitable for recording information on an optical recording medium for recording information three-dimensionally by laser light irradiation, and an optical recording / reproducing apparatus and method using these methods.

  In recent years, with the development of technology for digitizing and recording moving images, still images, etc., large-capacity data has been handled, and optical recording media such as optical discs have been increased in capacity. There is a tendency to promote. As a technique for increasing the capacity of this optical recording medium, an improvement in surface density and a technique of multilayering the optical recording medium are well known.

Improvement in surface density can be realized by shortening the wavelength of the laser beam used for recording or reproduction, increasing the NA (Numerical Aperture) of the objective lens for condensing the laser beam, and reducing the size of the focused spot. . On the other hand, multilayering of optical recording media is realized by adopting a structure in which two or more layers of sheets on which reflective films and recording films are formed are stacked while avoiding eccentricity and bending, and information can be recorded and reproduced on a plurality of layers. In this way, the capacity is increased (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-242677 (page 3-4, FIG. 1)

  However, in the improvement of the conventional surface density, the shortening of the wavelength of the laser beam used and the increase of the NA of the objective lens are close to the limits, and it is difficult to increase the surface density further. . In addition, it takes a lot of labor and cost to produce a recording medium by stacking recording surfaces in multiple layers, resulting in an increase in the unit price of the optical recording medium. Therefore, development of a large-capacity recording medium that is inexpensive and easy to manufacture and that is easy to use for recording and reproduction is required, and an optical recording and reproducing apparatus that can record and reproduce information on this recording medium is also required. It is said that.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to focus on recording a signal on an optical recording medium in which the capacity of the recording medium is increased without complicating the structure. And a tracking control method, and an optical recording / reproducing apparatus and method using the focus and tracking control method.

In order to achieve the above object, the present invention records a signal three-dimensionally on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes, and An optical recording / reproducing apparatus for reproducing a signal recorded on the optical recording medium, wherein the first laser light is generated by a laser generating means for generating a first laser light and a second laser light; 1. Thickness acquisition means for acquiring the thickness of the recording layer from each reflected light obtained by condensing in order on the second reference surface; and the second reference light of the optical recording medium using the second laser light. Information acquisition means for acquiring tracking information in the radial direction of the optical recording medium and address information indicating a two-dimensional position of the optical recording medium from reflected light obtained by condensing on the surface; and the acquired recording the first laser based on the thickness before and Kia dress information layer Focus position information acquisition means for obtaining the focal position of the light in the recording layer in the thickness direction, and a focus on the second reference plane of the second laser light by the tracking information obtained by the information acquisition means Tracking control means for simultaneously performing tracking control for the radial direction of the position and tracking control for the focal position of the first laser beam in the recording layer with respect to the radial direction, and a recording signal to be recorded on the optical recording medium In order to record by irradiating the focal position obtained by the focal position information acquisition means with the modulation means for modulating the first laser light and the first laser light modulated by the recording signal, the first laser light is recorded. and focus control means for focusing the laser light to the focal position of the first laser beam at the focal position of the thickness direction of the recording layer Characterized by comprising a reproduction signal obtaining means for obtaining a reproduction signal from the reflected light obtained by the light.

In the present invention, the focal position information acquisition unit may change a focal position of the first laser beam according to the address information.
In the present invention, when recording in a coil shape that moves in the thickness direction as it rotates while maintaining a constant radius concentrically on the recording layer of the optical recording medium, the focal position information acquisition means If the recording layer thickness is t, the number of recording layers in the thickness direction is n, the target recording layer is m, and the recording is performed at an address having an angle θ and a radius r indicating the two-dimensional position , the thickness is A direction pitch DP = t / n, an offset amount OFS = DP × (θ / 360 degrees) is obtained, and a target thickness d in the recording layer on which the first laser beam is focused is set to d = m × DP + OFS. It is characterized by.
In the present invention, the tracking control means may be configured such that when the number of arrangements in the thickness direction of the recording layer of recording signals having the same radius from the rotation center axis of the recording layer reaches a predetermined number, A radius of the focal position in the recording layer from the rotation center axis is changed.
In the present invention, the first and second laser beams have different wavelengths.

The present invention also provides an optical reproducing apparatus for reproducing a signal recorded three-dimensionally on a disc-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes. Laser generating means for generating one laser beam and a second laser beam, and each of the first laser beams obtained by condensing the first laser beam in advance on the first and second reference surfaces of the optical recording medium in advance. Thickness acquisition means for acquiring the thickness of the recording layer from the reflected light, and the radius of the optical recording medium from the reflected light obtained by condensing the second laser light on the second reference surface of the optical recording medium a tracking information for direction, information acquisition means for acquiring address information indicating the two-dimensional position of the optical recording medium, the first laser based on the thickness before and Kia dress information of the obtained recording layer Focus for determining the focal position of the thickness direction in the recording layer of light Position information acquisition means, tracking control of the focal position of the second laser light on the second reference plane in the radial direction and tracking of the first laser light according to the tracking information obtained by the information acquisition means Tracking control means for simultaneously performing tracking control in the radial direction of the focal position in the recording layer, and focus control means for focusing the first laser beam on the focal position obtained by the focal position information acquiring means And reproduction signal acquisition means for obtaining a reproduction signal from reflected light obtained by condensing the first laser light at the focal position in the thickness direction in the recording layer.

The present invention also provides an optical recording apparatus for three-dimensionally recording a signal on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes, the first laser A laser generating means for generating light and a second laser beam, and reflected light obtained by condensing the first laser beam in advance on the first and second reference surfaces of the optical recording medium in advance. Thickness acquisition means for acquiring the thickness of the recording layer, and tracking in the radial direction of the optical recording medium from reflected light obtained by condensing the second laser light on the second reference surface of the optical recording medium information and the information acquisition means for acquiring address information indicating the two-dimensional position of the optical recording medium, said first laser light based on the thickness before and Kia dress information of the obtained recording layer Focus position information for obtaining the focus position in the thickness direction in the recording layer And tracking control of the focal position of the second laser beam on the second reference plane in the radial direction and the recording layer of the first laser beam according to the tracking information obtained by the information acquisition unit Tracking control means for simultaneously performing tracking control of the focal position in the radial direction, modulation means for modulating the first laser light with a recording signal to be recorded on the optical recording medium, and modulation with the recording signal Focus control means for adjusting the focus of the first laser light to the focus position in order to irradiate and record the focus position obtained by the focus position information acquisition means with the first laser light. It is characterized by.

In the present invention, a signal is recorded three-dimensionally on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes, and the three-dimensionally recorded signal is recorded. An optical recording / reproducing method for reproducing a signal, the step of generating a first laser beam and a second laser beam;
Acquiring the thickness of the recording layer from each reflected light obtained by condensing the first laser light in advance on the first and second reference surfaces of the optical recording medium in advance; Tracking information in the radial direction of the optical recording medium from reflected light obtained by condensing a laser beam on the second reference surface of the optical recording medium, and address information indicating a two-dimensional position of the optical recording medium acquiring, determining a focal position of the thickness direction of the recording layer of the based on the thickness before and Kia dress information of the acquired recording layer a first laser beam, which is the acquired Tracking control of the focal position of the second laser beam on the second reference plane with respect to the radial direction and tracking of the focal position of the first laser beam in the recording layer according to the tracking information with respect to the radial direction. And performing tracking control at the same time, a step of modulating said first laser beam at the recording signal to be recorded on the optical recording medium, in the determined focus position of the first laser light modulated by the recording signal In order to irradiate and record, the step of focusing the first laser beam on the focal position and condensing the first laser beam on the focal position in the thickness direction in the recording layer are obtained. Obtaining a reproduction signal from the reflected light.

  As described above, in the present invention, the recording layer of the optical recording medium is made thick, and further, the first and second reference planes are provided with the recording layer interposed therebetween. Focus control for adjusting the focal point of the first laser beam to a predetermined position in the thickness direction in the recording layer based on the information obtained by irradiating the first and second laser beams having different values and the focal point in the recording layer Recording control is performed by three-dimensionally scanning the recording layer with the first laser light modulated by the recording information by performing tracking control to match a predetermined position in the radial direction of The focus control of the second laser beam is similarly adjusted to a predetermined position in the thickness direction in the recording layer and the tracking control is performed to adjust the focus to a predetermined position in the radial direction in the recording layer. In the recording layer A three-dimensionally recorded signal layer is recorded on a thick recording layer by scanning the dimensionally recorded signal recording row with the focus of the first laser beam and reproducing the recorded information from the reflected light obtained thereby. A large amount of information can be recorded and reproduced with a wide spread. Moreover, the recording layer of the optical recording medium is composed of a single layer, and the first and second reference surfaces having different light reflectivities are formed on both surfaces of the recording layer. The manufacturing cost of the optical recording medium that can be made can be reduced.

According to the present invention, the structure is complicated by recording and reproducing information three-dimensionally on the recording layer of an optical recording medium in which a recording layer having a thickness is disposed between reference surfaces for obtaining focus and tracking information. Thus, the capacity of the recording medium can be easily increased.
In addition, since the focus and tracking information is obtained from the reference surface, the recording layer may be a single layer integrated in the thickness direction. Therefore, there is no stacking process in manufacturing, and there is no need for adjustment of mutual eccentricity between layers. The optical recording medium can be easily and inexpensively manufactured.

  For the purpose of increasing the recording density without complicating the structure, the optical recording medium is constituted by a recording layer in which a reference surface is formed on both sides, and the first and second laser beams are generated. By performing three-dimensional focus control and tracking control of the first laser beam in the recording layer based on information obtained by scanning the two reference surfaces with two laser beams, information is stored in the optical recording layer. This was realized by recording with a three-dimensional spread.

  FIG. 1 is a cross-sectional view showing a configuration of an optical recording medium according to the first embodiment of the present invention. The optical recording medium 50 has a disk shape with a thickness of about 1 mm. A thick recording layer 2 is formed in the substrate 1, and a focus reference surface and a recording pitch determination reference are formed on the bottom surface of the recording layer 2. A surface (Al reflective film) 3 is formed, and a reflective surface of a dielectric thin film is formed on the upper surface of the recording layer 2 as a reference surface 4 for depth direction control. A portion indicated by reference numeral 60 in the recording layer 2 is a recording signal string.

  The recording layer 2 has a characteristic that optical properties change by irradiation with laser light or the like, and reproduction light is modulated by this change. For example, an internal electric field is generated by laser light irradiation and the refractive index changes. There are photorefractive media and photopolymer media in which the refractive index changes due to reaction between molecules or within molecules caused by light irradiation. In the recording layer 2 for recording signals, the absorption with respect to the wavelength of the laser beam used for recording or reproduction is smaller than that of the phase change recording film.

  Next, the signal recording form of the optical recording medium 50 will be described. As shown in the perspective view of FIG. 2A, the recording signal array 60 is such that the signal moves in the thickness direction as it rotates concentrically with the recording layer 2 of the optical recording medium 50 while maintaining a constant radius. That is, it is recorded in a coil shape. As shown in the plan view of FIG. 2B, the signals arranged in the form of a coil are arranged concentrically with a constant radial interval, thereby spreading three-dimensionally inside the recording layer 2. A signal is recorded.

  According to the present embodiment, the recording capacity 2 can be dramatically increased by forming a thick recording layer 2 on the optical recording medium 50 and recording a signal three-dimensionally on the recording layer 2. it can. Further, since the recording layer 2 of the optical recording medium 50 is a single recording layer and has a simple structure in which the reference surfaces 4 and 3 are formed on the upper and lower surfaces, and an inexpensive material such as a photopolymer medium can be used. The manufacturing cost can be reduced.

  In the multilayer film structure, the recording layer is divided into layers, so that the attenuation in the thickness direction of the laser light increases. In the single recording layer 2, the attenuation can be kept small, and the adjustment of the intensity of the laser beam can be simplified. Further, when the recording signal is reproduced, when the recording signal train is arranged in a multilayer spiral shape in the recording layer 2, a pickup jump from the outermost periphery to the inner periphery occurs when the layers are switched. In the case where the recording signal train is arranged, the pickup does not move greatly, and the mechanical movement control of the pickup can be made easy and highly accurate.

  FIG. 3 is a configuration diagram showing the configuration of an optical recording medium recording / reproducing apparatus according to the second embodiment of the present invention. An optical recording medium recording / reproducing apparatus includes a recording / reproducing optical system, a servo optical system, and a control system.

  The optical system for recording and reproduction includes a 405 nm laser diode (LD) 11, a half-wave plate (HWP) 12, a polarization beam splitter (PBS) 13, a quarter-wave plate (QWP) 14, and a spherical aberration correction lens 15. , Expander lenses 16 and 17, a condensing lens 18, and a cylindrical lens 19.

  The servo optical system includes a 690 nm laser diode (LD) 20, a diffraction grating 21, a half-wave plate (HWP) 22, a polarization beam splitter (PBS) 23, a quarter-wave plate (QWP) 24, Expander lenses 25 and 26, dichroic mirror 27, spherical aberration correction lens 28, objective lens 29, condenser lens 30, and cylindrical lens 31 are included. Note that the dichroic mirror 27, the spherical aberration correction lens 28, and the objective lens 29 are also used as an optical system for recording and reproduction.

  The control system includes a photodiode (PD) 32, a signal calculation processing unit 33, a focus determination / tracking determination and address recognition unit 34, an actuator drive circuit 35, a rotation speed setting / radius setting unit 36, an actuator 38 for an objective lens, and optical recording. An Rθ stage 39 on which the medium 50 is placed, a photodiode (PD) 40, a signal calculation processing unit 41, a focus reference storage / focus position setting unit 42, an actuator drive circuit 43, and an expander lens actuator 44 are provided.

  Next, the operation of the present embodiment will be described with reference to the flowchart shown in FIG. First, when performing three-dimensional signal recording / reproduction with respect to the optical recording medium 50, it becomes a problem how to perform focus control and tracking control when recording / reproducing the signal. This is solved by providing the reference surfaces 3 and 4 with the recording layer 2 of the optical recording medium 50 interposed therebetween. Hereinafter, how to perform focus control and tracking control in three-dimensional signal recording / reproduction will be described. However, when a signal is recorded three-dimensionally on the optical recording medium 50, or recorded three-dimensionally. The method of control is also common when reproducing the existing signal.

  First, a laser beam 100 having a wavelength of 690 nm is emitted from the laser diode 20, and this laser beam is emitted from the diffraction grating 21, the half-wave plate 22, the polarization beam splitter 23, the quarter-wave plate 24, the expander lenses 25 and 26, and the dichroic. Irradiation is performed so as to focus on the reference surface 3 of the optical recording medium 50 via the mirror 27, the spherical aberration correction lens 28, and the objective lens 29.

  The laser reflected light reflected by the reference surface 3 is incident on the objective lens 29, the spherical aberration correction lens 28, the dichroic mirror 27, the expander lenses 26 and 25, the quarter wavelength plate 24, and the polarization beam splitter 23. , And the light is condensed on the photodiode 32 through the condensing lens 30 and the cylindrical lens 31. At this time, the rotation speed setting / radius setting unit 36 rotates the Rθ stage 39 with a default value.

  As shown in FIG. 4A, the light receiving surface of the photodiode 32 has light receiving areas A, B, C, and D for main spots and light receiving areas E and F for subspots, and photoelectric conversion is performed in these light receiving areas. The A to F signals are input to the signal processing unit 33. The signal processing unit 33 calculates the focus error signal FE = (A + C) − (B + D), calculates the pull-in signal Pull-in = A + B + C + D, and calculates the tracking error signal TR = EF. The FE, the pull-in signal Pull-in, and the tracking signal TR are calculated, and these signals are sent to the focus determination / tracking determination and address recognition unit 34.

  The focus determination / tracking determination and address recognition unit 34 is formed on the reference surface 3 based on the focus determination with respect to the reference surface 3 of the laser beam 100 based on the input focus signal FE, the pull-in signal Pull-in, and the tracking signal TR. Tracking determination and address recognition are performed from the groove shape, and a focus determination result, a pull-in signal Pull-in, and a tracking signal TR are output to the actuator drive circuit 35.

  If there is a focus shift in the focus determination, the actuator drive circuit 35 controls the objective lens actuator 38 so as to eliminate the shift, and focuses the laser beam 100 on the reference surface 3 of the optical recording medium 50. The pull-in signal Pull-in is used for a servo pull-in operation when focusing. By repeating the above operation, the reference plane 3 is searched with the laser beam 100, and as a result, when the focus of the laser beam 100 matches the reference plane 3, the actuator drive circuit 35 causes the actuator 38 for the objective lens to fluctuate the surface of the reference plane 3. Following driving is performed to lock the focus (step S1).

  In order to make the focus determination / tracking determination and address recognition unit 34 identify the surface of the substrate 1, the reference surface (depth about 100 μm) 4, and the reference surface (depth about 1 mm) 3, the reflectance of the reference surface 4. The reflectance (about 50%) of the reference surface 3 is increased with respect to (about 4%). Further, when the objective lens 29 is driven, the spherical aberration associated with the focal depth is also corrected at the same time.

  Next, a laser beam 200 having a wavelength of 405 nm is emitted from the laser diode 11, and this laser beam is divided into a half-wave plate 12, a polarization beam splitter 13, a quarter-wave plate 14, a spherical aberration correction lens 15, an expander lens 16, 17. Irradiation is focused on the reference surface 3 of the optical recording medium 50 through the dichroic mirror 27, the spherical aberration correction lens 28, and the objective lens 29.

  The laser reflected light reflected by the reference surface 3 is incident on the objective lens 29, the spherical aberration correction lens 28, and the dichroic mirror 27, where the path is changed by 90 degrees, and the expander lenses 17 and 16, the spherical aberration correction lens 15, The light is incident on the quarter-wave plate 14 and the polarization beam splitter 13, where the path is changed by 90 degrees, and the light is condensed on the photodiode 40 via the condenser lens 18 and the spherical aberration correction lens 15.

  As shown in FIG. 4B, the light receiving surface of the photodiode 40 has light receiving areas A, B, C, and D for main spots, and A to D signals photoelectrically converted in these light receiving areas are signal processing units. 41 is output. The signal processing unit 41 calculates the focus error signal FE = (A + C) − (B + D), calculates the pull-in signal Pull-in = A + B + C + D, calculates the reproduction signal RF = A + B + C + D, and outputs the focus error signal FE and the pull-in signal. The data is sent to the focus reference storage / focus position setting unit 42. The focus reference storage / focus position setting unit 42 outputs the focus determination result and the pull-in signal Pull-in to the actuator drive circuit 43.

  The actuator drive circuit 43 controls the expander lens actuator 44 so that the shift is eliminated when there is a shift in focus in the focus determination, and the focus of the laser beam 200 is adjusted to the reference plane 3 of the optical recording medium 50. At this time, the pull-in signal Pull-in is used for a servo pull-in operation when focusing. By repeating the above operation, the reference plane 3 is searched with the laser beam 200. As a result, when the focus of the laser beam 200 matches the reference plane 3, the actuator drive circuit 43 locks the actuator 44 for the expander lens. At this time, the focus reference storage / focus position setting unit 42 stores the focus lock detection voltage 2 at the focus locked position (step S2).

  The focus lock detection voltage 2 is obtained by normalizing the focus error signal FE with the detected total light amount signal. When the expander lens 16 is driven, the spherical aberration associated with the recording depth is corrected at the same time so that the spherical aberration is within a predetermined range even when the depth of the reference surface 3 varies.

  The laser beam 200 having a wavelength of 405 nm emitted from the laser diode 11 is irradiated so as to focus on the reference surface 4 of the optical recording medium 50 through the same optical system as described above, and the reflected laser light from the reference surface 4 is irradiated with the photodiode. The light is received at 40 and the received light signal is input to the signal calculation processing unit 41. Since the signal calculation processing unit 41 calculates the focus error signal FE and the pull-in signal Pull-in and inputs them to the focus reference storage / focus position setting unit 42 in the same manner as described above, the actuator drive circuit 43 focuses the laser beam 200 on the focus. The focus is locked according to the reference surface 4 of the optical recording medium 50. At this time, the focus reference storage / focus position setting unit 42 stores the focus lock detection voltage 1 at the focus locked position (step S3).

  The focus lock detection voltage 1 is obtained by normalizing the focus error signal FE with the detected total light amount signal. When the expander lens 16 is driven, the spherical aberration associated with the recording depth is corrected at the same time so that the spherical aberration is within a predetermined range even when the depth of the reference surface 4 varies.

  By the way, the actuator drive circuit 35 drives the actuator 38 so that the tracking signal TR input from the focus determination / tracking determination / address recognition unit 34 becomes zero so that the objective lens 29 is moved in the radial direction of the optical recording medium 50. Control is performed so that the laser beam 100 tracks the track guide pattern (groove or address bit string with address wobble) in the reference plane 3 (step S4).

  The focus determination / tracking determination / address recognition unit 34 sets the rotation number in the rotation number setting / radius setting unit 36. Thereby, the rotation speed setting / radius setting section 36 rotates the Rθ stage 39 at a predetermined rotation speed. At that time, the focus determination / tracking determination and address recognition unit 34 reads the address (information of angle θ and radius r) from the pull-in signal PuIl-in, and sets the radius of the Rθ stage 39 so that the read address becomes a predetermined address. The optical recording medium 50 is moved in the direction (step S5). Further, by controlling the rotation speed of the Rθ stage 39 in accordance with the read radius r, the optical recording medium 50 can be scanned with the laser light 100 (or 200) at a constant linear velocity, for example.

  The focus reference storage / focus position setting unit 42 obtains the thickness t of the recording layer 2 based on the difference between the focus lock detection voltage 1 and the detection voltage 2. At that time, assuming that the number of recording layers in the depth direction is n and the target recording layer is m (= 0 to n−1), the depth direction pitch DP = t / n and the offset amount OFS = DP × (θ / 360 °). ) And a target depth d = m × DP + OFS of the recording layer 2 is determined (step S6). Note that m is the number of repetitions of the same address read by the focus determination / tracking determination and address recognition unit 34 (the same as the number of rotations when recording on the recording layer of the optical recording medium 50 is performed in one rotation). Is notified from the focus determination / tracking determination / address recognition unit 34 to the focus reference storage / focus position setting unit 42.

  Next, the focus reference storage / focus position setting unit 42 controls the drive of the expander lens 16 via the actuator drive circuit 43, thereby adjusting the focus of the laser light 200 emitted from the laser diode 11 to the depth d ( Step S7).

  By the operations from steps S1 to S7 described above, the laser beam 100 emitted from the laser diode 20 is focused on the reference plane 3, and the groove or address pit formed on the reference plane 3 is scanned by the focal point of the laser beam 100. In order to perform tracking control, the focal point of the laser beam 200 emitted from the laser diode 11 having the same optical axis is directly above the groove or address pit in the recording layer 2 of the optical recording medium 50 and The position indicated by the depth d is scanned.

  Here, the focus and tracking control of the optical pickup (portion excluding the control system described with reference to FIG. 1) in the case of recording / reproducing a signal to / from the optical recording medium 50 are the same, and the steps S1 to S7 described above are the same. When the focus and tracking control becomes possible in the operation, the operation of step S4 to step S7 is repeated thereafter, so that the focus of the laser beam 200 emitted from the laser diode 11 is within the recording layer 2 of the optical recording medium 50. The position indicated by the depth d is scanned immediately above the groove or address pit.

  At this time, during recording, the output level of the laser beam 200 emitted from the laser diode 11 by the recording signal 200 is usually higher than that during reproduction, and the laser beam 200 is modulated by the recording signal 90. Then, a modulation signal (recording signal) is recorded on the recording layer 2 of the optical recording medium 50 in the signal sequence as shown in FIG. 4 (step S8).

  On the other hand, at the time of reproduction, the unmodulated laser beam 200 is focused on the recording layer 2 of the optical recording medium 50 onto a signal sequence as shown in FIG. 4, and the reflected light is modulated by the recording signal and modulated reflected light. Is received by the photodiode 40 and further outputted as a reproduction signal from the signal calculation processing unit 41 to a reproduction system of the next stage (not shown). Thereby, video, audio, and the like are reproduced (step S8).

  According to the present embodiment, tracking control information (tracking error information and address information) when performing three-dimensional recording on the recording layer 2 of the optical recording medium 50 with a laser beam 200 having a wavelength of 405 nm is used as a laser having a wavelength of 690 nm. The reference plane 3 and the reference plane which are obtained by scanning the reference plane 3 in the recording layer 2 with the light 100 and measured by scanning the reference plane 3 and the reference plane 4 in the recording layer 2 with the laser beam 200 in advance. The recording or reproducing position in the depth direction of the recording layer 2 is acquired based on the distance between the surfaces 4 and the address information, and is specified by the position in the depth direction and the radial direction position by the tracking control information. By performing the focus control and tracking control so that the laser beam 200 is focused at the recording or reproduction position, a large capacity signal is received in the recording layer 2 of the optical recording medium 50. It is possible to perform the recording. As a result, large-capacity recording / reproduction can be accurately and smoothly performed on the optical recording medium 50 on which signals are recorded three-dimensionally.

  In the above embodiment, in order to change the relative focus bias, the objective lens 29 or another lens can be driven in the optical axis direction, or the spherical aberration amount of the objective lens 29 can be changed. It is assumed that the objective lens 29 has a spherical aberration amount that varies depending on the pupil diameter, for example, and has a mechanism that can change the pupil diameter.

  In addition, the present invention is not limited to the above-described embodiment, and can be implemented in various other forms in specific configurations, functions, operations, and effects without departing from the gist thereof. In the present embodiment, the laser beams 100 and 200 having the wavelengths of 405 nm and 690 nm are used. However, the recording layer 2 of the optical recording medium 50 is sensitive to one wavelength and the sensitivity is to the other wavelength. Any two-wavelength laser light that is small and has a wavelength difference that can be separated by the dichroic mirror 27 can be used in the same manner.

  Further, even if the laser beam to be used is not different in wavelength, it is possible to use a difference in sensitivity with respect to the recording layer 2 by utilizing the difference in power and the difference in polarization direction, and the laser beam can be separated. Can do.

  Further, as a material for forming the recording layer 2 of the optical recording medium 50, a sufficient transmittance can be obtained with respect to the wavelengths of the recording or reproducing laser beam and the laser beam for controlling the depth direction, and at the same time, the recording or reproducing laser. Various materials can be used as long as they have recording sensitivity to light.

  In the above embodiment, the recording signal trains are arranged in concentric coils. However, the present invention is not limited to this, and a spiral recording signal train having a constant depth is arranged, and the same spiral is formed by changing the depth. A structure may be adopted in which two or more layers of recording signal trains are arranged. In this case, the groove provided on the tracking reference surface 3 is not a concentric circle but needs to be formed in a spiral shape similar to the recording signal train.

1 is a cross-sectional view showing a configuration of an optical recording medium according to a first embodiment of the present invention. It is the figure which showed the shape of the signal sequence of the signal recorded on the optical recording medium shown in FIG. It is the block diagram which showed the structure of the recording / reproducing apparatus of the optical recording medium based on the 2nd Embodiment of this invention. FIG. 4 is an enlarged view showing a light receiving surface of the photodiode shown in FIG. 3. 4 is a flowchart showing an operation procedure of the recording / reproducing apparatus shown in FIG. 3.

  DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Recording layer, 3, 4 ... Reference plane, 11, 20 ... Laser diode (LD), 12, 22 ... 1/2 wavelength plate (HWP), 13, 23 ... Polarization Beam splitter (PBS), 14, 24 ... 1/4 wavelength plate (QWP), 15, 28 ... Spherical aberration correction lens, 16, 17, 25, 26 ... Expander lens, 18, 30 ... Collection Optical lens, 19, 31 ... Cylindrical lens, 21 ... Diffraction grating, 27 ... Dichroic mirror, 29 ... Objective lens, 32, 40 ... Photodiode (PD), 33, 41 ... Signal calculation processing unit, 34... Focus determination / tracking determination and address recognition unit, 35, 43... Actuator drive circuit, 36... Rotation speed setting / radius setting unit, 38. Rθ stage, 42 ...... focus criterion storage focus position setting unit, 44 ...... expander lens actuator 50 ...... optical recording medium.

Claims (10)

Optical recording for recording a signal three-dimensionally on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes and reproducing the three-dimensionally recorded signal A playback device,
Laser generating means for generating a first laser beam and a second laser beam;
Thickness acquisition means for acquiring the thickness of the recording layer from each reflected light obtained by condensing the first laser light in advance on the first and second reference surfaces of the optical recording medium in advance;
Tracking information in the radial direction of the optical recording medium from reflected light obtained by condensing the second laser light on the second reference surface of the optical recording medium, and a two-dimensional position of the optical recording medium Information acquisition means for acquiring address information indicating
And focus position information obtaining means for obtaining a focal position of the thickness direction of the recording layer of the first laser light based on the thickness before and Kia dress information of the acquired recording layer,
Tracking control of the focal position of the second laser beam on the second reference plane in the radial direction and tracking of the first laser beam in the recording layer based on the tracking information obtained by the information acquisition means. Tracking control means for simultaneously performing tracking control with respect to the radial direction of the focal position;
Modulation means for modulating the first laser beam with a recording signal to be recorded on the optical recording medium;
Focus for focusing the first laser beam on the focal position in order to irradiate and record the first laser beam modulated by the recording signal on the focal position obtained by the focal position information acquisition unit. Control means;
Reproduction signal acquisition means for obtaining a reproduction signal from reflected light obtained by condensing the first laser beam at the focal position in the thickness direction in the recording layer;
An optical recording / reproducing apparatus comprising:   The optical recording / reproducing apparatus according to claim 1, wherein the focal position information acquisition unit changes a focal position of the first laser beam in accordance with the address information.   3. The focal position information acquisition unit changes the focal position of the first laser beam so that recording signal intervals of the same address arranged in the thickness direction of the recording layer are equally spaced. Optical recording / reproducing apparatus. When recording in a coil shape that moves in the thickness direction as it rotates while maintaining a constant radius concentrically on the recording layer of the optical recording medium,
The focal position information acquisition means sets the recording layer thickness to t, the number of recording layers in the thickness direction to n, the target recording layer to m, and an address composed of an angle θ and a radius r indicating the two-dimensional position. When recording, the thickness direction pitch DP = t / n, the offset amount OFS = DP × (θ / 360 degrees) is obtained, and the target thickness d in the recording layer for focusing the first laser beam is set to d = optical recording and reproducing apparatus according to claim 1, characterized in that the m × DP + OFS.   When the number of arrangements in the thickness direction of the recording layer of the recording signals having the same radius from the rotation center axis of the recording layer reaches a predetermined number, the tracking control unit focuses the first laser beam in the recording layer. 2. The optical recording / reproducing apparatus according to claim 1, wherein a radius of the position from the rotation center axis is changed.   6. The optical recording / reproducing apparatus according to claim 5, wherein a change in radius of the focal position from the rotation center axis is at equal intervals.   2. An optical recording / reproducing apparatus according to claim 1, wherein the first and second laser beams have different wavelengths. An optical reproducing apparatus for reproducing a signal three-dimensionally recorded on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes,
Laser generating means for generating a first laser beam and a second laser beam;
Thickness acquisition means for acquiring the thickness of the recording layer from each reflected light obtained by condensing the first laser light in advance on the first and second reference surfaces of the optical recording medium in advance;
Tracking information in the radial direction of the optical recording medium from reflected light obtained by condensing the second laser light on the second reference surface of the optical recording medium, and a two-dimensional position of the optical recording medium Information acquisition means for acquiring address information indicating
And focus position information obtaining means for obtaining a focal position of the thickness direction of the recording layer of the first laser light based on the thickness before and Kia dress information of the acquired recording layer,
Tracking control of the focal position of the second laser beam on the second reference plane in the radial direction and tracking of the first laser beam in the recording layer based on the tracking information obtained by the information acquisition means. Tracking control means for simultaneously performing tracking control with respect to the radial direction of the focal position;
A focus control means for focusing the first laser beam on the focal position obtained by the focal position information obtaining means;
Reproduction signal acquisition means for obtaining a reproduction signal from reflected light obtained by condensing the first laser beam at the focal position in the thickness direction in the recording layer;
An optical reproducing apparatus comprising: An optical recording apparatus that three-dimensionally records a signal on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes,
Laser generating means for generating a first laser beam and a second laser beam;
Thickness acquisition means for acquiring the thickness of the recording layer from each reflected light obtained by condensing the first laser light in advance on the first and second reference surfaces of the optical recording medium in advance;
Tracking information in the radial direction of the optical recording medium from reflected light obtained by condensing the second laser light on the second reference surface of the optical recording medium, and a two-dimensional position of the optical recording medium Information acquisition means for acquiring address information indicating
And focus position information obtaining means for obtaining a focal position of the thickness direction of the recording layer of the first laser light based on the thickness before and Kia dress information of the acquired recording layer,
Tracking control of the focal position of the second laser beam on the second reference plane in the radial direction and tracking of the first laser beam in the recording layer based on the tracking information obtained by the information acquisition means. Tracking control means for simultaneously performing tracking control with respect to the radial direction of the focal position;
Modulation means for modulating the first laser beam with a recording signal to be recorded on the optical recording medium;
Focus for focusing the first laser beam on the focal position in order to irradiate and record the first laser beam modulated by the recording signal on the focal position obtained by the focal position information acquisition unit. Control means;
An optical recording apparatus comprising: Optical recording for recording a signal three-dimensionally on a disk-shaped rotating optical recording medium having a recording layer sandwiched between first and second reference planes and reproducing the three-dimensionally recorded signal A playback method,
Generating a first laser beam and a second laser beam;
Obtaining the thickness of the recording layer from each reflected light obtained by condensing the first laser light in advance on the first and second reference surfaces of the optical recording medium in advance;
Tracking information in the radial direction of the optical recording medium from reflected light obtained by condensing the second laser light on the second reference surface of the optical recording medium, and a two-dimensional position of the optical recording medium Obtaining address information indicating
Determining a focal position of the thickness direction of the recording layer of the first laser light based on the thickness before and Kia dress information of the acquired recording layer,
Tracking control of the focal position of the second laser beam on the second reference plane with respect to the radial direction according to the acquired tracking information and the focal position of the first laser beam in the recording layer. Simultaneously performing tracking control in the radial direction;
Modulating the first laser beam with a recording signal to be recorded on the optical recording medium;
Focusing the first laser beam on the focal position in order to irradiate and record the determined focal position with the first laser beam modulated by the recording signal;
Obtaining a reproduction signal from reflected light obtained by condensing the first laser beam at a focal position in the thickness direction in the recording layer;
An optical recording / reproducing method comprising:

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