JP2005251290A - Recording and reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording and reproducing device in which a recording medium can be accurately irradiated by a light to be used for recording and reproducing the information. <P>SOLUTION: An object light 71 is converged by an objective lens 310, and a reference light 72 is deflected by a hologram element 312, and by the both lights, an information recording area 106 of a hologram recording medium 1 is irradiated. By a detection light 80 transmitted through the objective lens 310, a servo information area 107 is irradiated. The positional information is detected by a photodetector 314 for servo in accordance with a reflected light of the detection light 80. By an actuator 320, the objective lens 310 and the hologram element 312 are controlled for moving to the focusing control direction or tracking control direction in accordance with a focusing drive signal and a tracking drive signal which are produced on the basis of the positional information. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording / reproducing apparatus that records information on a hologram memory medium and reproduces the recorded information.

  In recent years, rewritable optical discs such as phase change type and magneto-optical type are widely used as information recording media. In order to further increase the recording density of these optical discs, techniques such as reducing the beam spot diameter and shortening the distance between adjacent tracks or adjacent bits are required.

  As described above, the density of optical discs is increasing year by year. However, since the above optical disc records data in a plane, the recording density is limited to the diffraction limit of light, and physical recording of high density recording is performed. Approaching the limit. Therefore, in order to further increase the capacity, three-dimensional (volume type) multiplex recording including the depth direction is required.

  Therefore, a hologram memory having both a large capacity derived from a three-dimensional multiple recording area and a high speed derived from a two-dimensional batch recording / reproducing system has attracted attention as a next-generation computer file memory. Hologram memory, for example, irradiates a recording medium formed by sandwiching a recording layer made of a photopolymer or the like between two glass plates with object light corresponding to recording information and reference light, and is generated by both lights The recorded interference fringes are recorded as a change in the refractive index of the recording material. When reproducing the information, only the reference light is irradiated to the recorded interference fringes, and the recorded information is based on the diffracted light of the reference light. The optical information corresponding to is extracted.

Since this hologram memory can multiplex-record a plurality of two-dimensional data in the same area, it has been attracting attention as a terabyte memory having a huge recording capacity while having the same shape as a CD or the like. As a reproducing apparatus for such a hologram memory, for example, as shown in Patent Document 1, a technique for writing a positioning signal as hologram information separately from a data signal has been proposed.
JP 2000-268380 A

  However, although the technique described in Patent Document 1 can record data on the entire surface of a recording medium, for example, when reproducing data in different drive devices, the deviation of the spindles of the respective drive devices. The center amount is different, and the amount of eccentricity changes every time the recording medium is chucked. Therefore, there is a problem that compatibility between apparatuses is poor and accurate positioning control is difficult.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a recording / reproducing apparatus that can accurately irradiate a recording medium with light used for recording and reproducing information. .

  The present invention has been made to solve the above problems, and the invention according to claim 1 irradiates an optical recording medium with object light and reference light, and interferes with the information of the object light on the optical recording medium. In the recording / reproducing apparatus for recording information as a fringe, irradiating the interference light with the reference light, and reproducing information based on the diffracted light of the reference light, the object light and the reference light are recorded with the information. A first irradiating means for irradiating an information recording area on the optical recording medium; and a second irradiating means for irradiating a control area different from the information recording area on the optical recording medium with detection light for position detection; A recording / reproducing apparatus comprising: a control unit that controls an irradiation position of the object light and the reference light by the first irradiation unit based on a position detection result by the detection light.

  In the control area different from the information recording area on the optical recording medium, for example, a concave or convex portion is formed, which is distinguished from the information recording area. The first irradiation unit and the second irradiation unit include a light source, a lens, and the like. The light source, the lens, and the like may be shared by the first irradiation unit and the second irradiation unit. The first irradiating means irradiates the information recording area with the object light to which the information to be recorded is added and the reference light for forming the interference fringes and reproducing the information, and the second irradiating means is the information recording The detection light is irradiated to a control area different from the area. The detection light has, for example, position information in a direction parallel to the recording surface of the optical recording medium or in a direction perpendicular to the recording surface, and the control means irradiates the object light and the reference light based on the position information. To control.

According to a second aspect of the present invention, in the recording / reproducing apparatus according to the first aspect, the first irradiating means transmits the object light and the reference light to the first or second main surface side of the optical recording medium. The second irradiating means irradiates the detection light from the main surface side irradiated with the object light and the reference light.
Both the object light, the reference light, and the detection light are applied to the optical recording medium from one of the first and second main surfaces of the optical recording medium.

  According to a third aspect of the present invention, in the recording / reproducing apparatus according to the first aspect, the first irradiating unit irradiates the object light from one main surface side of the first and second main surfaces. In addition, the reference light is irradiated from the other main surface side, the second irradiation means is irradiated with the detection light from the first or second main surface side, and the control means When the main surface to be irradiated and the main surface to be irradiated with the detection light are the same, the irradiation position of the object light is controlled based on the detection result of the position by the reflected light of the detection light. The position of the reference light is controlled based on the position detection result of the transmitted light of the detection light, and the main surface irradiated with the object light is different from the main surface irradiated with the detection light. In the case, based on the detection result of the position by the transmitted light of the detection light, the object Controls the irradiation position of the light, based on the position of the detection result of the reflected light of the detection light, and controlling the irradiation position of the reference light.

  When the object light is irradiated from the first main surface side, the reference light is irradiated from the second main surface side, and when the object light is irradiated from the second main surface side, the reference light is Irradiated from the first main surface side. Further, the detection light is irradiated from the main surface side of either the first main surface or the second main surface. When the object light and the detection light are irradiated from the same main surface side, the control means determines the irradiation position of the object light based on the detection result of the position of the detection light reflected by the optical recording medium. And the irradiation position of the reference light is controlled based on the position detection result of the detection light transmitted through the optical recording medium. In addition, when the object light and the detection light are irradiated from different main surface sides, the control unit determines the irradiation position of the object light based on the detection result of the position of the detection light transmitted through the optical recording medium. And the irradiation position of the reference light is controlled based on the detection result of the position of the detection light reflected by the optical recording medium.

  According to a fourth aspect of the present invention, in the recording / reproducing apparatus according to the first aspect, the first irradiating unit irradiates the object light from one main surface side of the first and second main surfaces. In addition, the reference light is irradiated from the other main surface side, and the second irradiation means irradiates the first detection light from the one main surface side irradiated with the object light and the reference light. The second detection light is irradiated from the other main surface side irradiated with the light, and the control means determines the irradiation position of the object light based on the position detection result by the reflected light of the first detection light. In addition to controlling, the irradiation position of the reference light is controlled based on the detection result of the position of the reflected light of the second detection light.

  When the object light is irradiated from the first main surface side, the reference light is irradiated from the second main surface side, and when the object light is irradiated from the second main surface side, the reference light is Irradiated from the first main surface side. The first detection light is irradiated from the same main surface side as the main surface irradiated with the object light, and the second detection light is irradiated from the same main surface side as the main surface irradiated with the reference light. Is done. The control means controls the irradiation position of the object light based on the detection result of the position of the first detection light reflected by the optical recording medium, and the second detection light reflected by the optical recording medium. The irradiation position of the reference light is controlled based on the position detection result by the reflected light.

According to a fifth aspect of the present invention, in the recording / reproducing apparatus according to the fourth aspect, the second irradiating unit irradiates the control areas different from each other with the first detection light and the second detection light. It is characterized by doing.
In order to perform position control with higher accuracy, the control area irradiated with the first detection light and the control area irradiated with the second detection light are defined as information recording areas irradiated with the object light and the reference light. It is desirable that the adjacent regions are sandwiched.

  According to a sixth aspect of the present invention, in the recording / reproducing apparatus according to the fourth or fifth aspect, the first irradiation unit includes an object light irradiation unit that irradiates the information recording area with the object light, and Reference light irradiation means for irradiating the information recording area with reference light, and the control means includes an irradiation position of the object light by the object light irradiation means, and an irradiation position of the reference light by the reference light irradiation means. Are controlled independently.

  According to a seventh aspect of the present invention, in the recording / reproducing apparatus according to any one of the first to sixth aspects, a polarization direction of the object light and the reference light and a polarization direction of the detection light are orthogonal to each other. It is characterized by that.

  The invention according to claim 8 is the recording / reproducing apparatus according to any one of claims 1 to 7, wherein the object light, the reference light, and the detection light are generated by the same light source. It is characterized by.

  According to the present invention, the position information is detected by the detection light, and based on the position information, the irradiation position on the recording medium of the light used for recording and reproducing the information is controlled. The effect that the light used for reproduction can be accurately irradiated onto the recording medium is obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a recording / reproducing apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a hologram recording medium (optical recording medium) on which information is recorded by interference fringes formed by object light and reference light. A spindle motor 2 rotates the hologram recording medium 1 at a constant linear velocity, for example, when the outer shape of the hologram recording medium 1 is a disk. The number of rotations is controlled by the output of the driver IC 7.

  Reference numeral 3 denotes an optical pickup (first and second irradiating means, control means), and optical components (first and second irradiating means) such as a laser light source, a collimator lens, an objective lens, and a polarization beam splitter (not shown). A focusing actuator (control means), a tracking actuator (control means), and a two-dimensional light detection array as a light receiving element. The objective lens is driven in the thickness direction of the hologram recording medium 1 by a focusing actuator, and is driven in the in-plane direction of the recording surface of the hologram recording medium 1 by a tracking actuator.

  A feed motor (control means) 4 is a mechanism for sending the optical pickup 3 from the inner periphery to the outer periphery of the hologram recording medium 1, for example. The feed motor 4 controls the position of the optical pickup 3 based on the drive signal of the tracking actuator. Reference numeral 5 denotes a signal processing IC which receives a data reproduction signal, an address signal, a spindle control signal, a focus error signal, and a track error signal based on the return light from the hologram recording medium 1 incident on a light receiving element such as a two-dimensional photodetection array. Generate. Further, the signal processing IC 5 generates a focusing drive signal and a tracking drive signal based on the generated focus error signal and track error signal, and outputs them to the driver IC 7 together with the spindle control signal.

  The address signal is a signal for detecting a physical address on the hologram recording medium 1 detected based on the data reproduction signal. The spindle control signal is a signal for controlling the rotation of the spindle motor 2, and is a signal based on the address signal. The focus error signal is a signal for detecting a focus shift of the irradiation laser in the optical pickup 3, and the track error signal is a signal for detecting a track shift of the irradiation laser in the optical pickup 3. The focus error signal is generated by the astigmatism method or the like based on the return light output obtained by the light receiving element in the optical pickup 3, for example. The track error signal is generated by, for example, a push-pull method.

  Reference numeral 6 denotes a CPU (Central Processing Unit), which controls the entire apparatus based on a control program stored in a ROM (ROM: Read Only Memory) (not shown). In the present embodiment, the CPU 6 controls various servo operations related to information recording and reproduction operations on the hologram recording medium 1.

  The driver IC 7 amplifies the focusing drive signal, the tracking drive signal, and the spindle control signal input from the signal processing IC 5 to desired magnitudes, and supplies them to the focusing actuator, tracking actuator, and spindle motor 2, respectively. Further, the feed motor drive signal generated from the tracking drive signal is amplified to a desired magnitude and supplied to the feed motor 4.

  FIG. 2 is a cross-sectional structure diagram showing a cross-sectional structure of the hologram recording medium 1. In the figure, reference numeral 100 denotes a substrate having a concave (convex) portion formed in advance. On the substrate 100, a semi-transmissive film layer 101, a protective layer 102, a recording layer 103, and a protective layer 104 are stacked in this order, and the protective layer 104 is covered with the substrate 105. The recording layer 103 can be expected to have high reading (reproduction) efficiency, recording and erasing can be repeated, and there is no deterioration in characteristics due to the recording layer 103. Multiple recording is possible and high resolution can be expected. A single crystal or the like is used.

  The distance A between the concave (convex) portions is approximately 100 to 500 (μm) depending on the optical system, and the interval B between the convex (concave) portions is approximately 0.1 to 2 (μm) although it depends on the optical system. ) The flat area between the concave (convex) parts is the information recording area 106, and the concave (convex) part is the control area (servo area) 107. Reference numerals 108 and 109 denote main surfaces of the hologram recording medium 1. The outer shape of the hologram recording medium 1 may be a disk type or a card type.

  Next, the irradiation method of the object light, the reference light, and the detection light according to the present embodiment will be described. The object light is light to which information to be recorded on the hologram recording medium 1 is added. The reference light is irradiated on the information recording area 106 of the hologram recording medium 1 together with the object light at the time of recording information to generate interference fringes, and is irradiated on the information recording area 106 of the hologram recording medium 1 at the time of reading information. This light is diffracted light including reproduction information. The detection light is light for irradiating the control area 107 of the hologram recording medium 1 to detect position information for position control of the object light and the reference light.

  FIG. 3 is a schematic reference diagram illustrating a state in which object light, reference light, and detection light are irradiated from the same main surface side of the hologram recording medium 1. The object light 71 and the reference light 72 are applied to the information recording area 106 of the hologram recording medium 1 from the main surface 108 side, and the detection light 80 is also applied to the control area 107 from the main surface 108 side. FIG. 4 is a schematic reference diagram showing the above-described irradiation state including the optical system 30. An optical system 30 for irradiating object light, reference light, and detection light is provided in the optical pickup 3. When the optical system 30 is initially adjusted, the relative positions of the object light 71, the reference light 72, and the detection light 80 are in-plane with respect to the information recording area 106 and the control area 107 of the hologram recording medium 1. Adjustment is made in each of the direction and the direction orthogonal to the recording surface.

  An in-plane direction orthogonal to the concave portion (convex portion) of the recording surface based on the reflected light of the detection light 80 applied to the control region 107 by a general track detection method, focus detection method, and address detection method in an optical disk. (Tracking control direction; left and right direction in FIG. 3) and the normal direction of the recording surface (focusing control direction; vertical direction in FIG. 3) and the position in the in-plane direction perpendicular to the tracking control direction are detected. Is done. When the outer shape of the hologram recording medium 1 is a disk shape, the tracking control direction is the radial direction of the disk, and the in-plane direction orthogonal to the tracking control direction is the direction along the circumference of the disk.

  The tracking control direction can be detected by, for example, the push-pull method, the focusing control direction can be detected by the astigmatism method, and the in-plane direction orthogonal to the tracking control direction is detected based on the address information configured in the control area 107. be able to. Regarding the control performed based on these detections, first, the focusing control direction is controlled based on the focus error signal generated from the detection light 80, and then the tracking control direction control is performed based on the track error signal. Subsequently, the position in the in-plane direction perpendicular to the tracking control direction is detected based on the address signal.

  When the hologram recording medium 1 is displaced due to eccentricity or surface vibration, the irradiation positions of the object beam 71 and the reference beam 72 are shifted from the positions in the tracking control direction and the focusing control direction to be recorded or reproduced. Therefore, recording or reproduction cannot be performed. Therefore, based on the reflected light of the detection light 80 irradiated to the control region 107, the above-described positional deviation is detected, and the detection light 80 is controlled to an appropriate position, thereby positioning relative to the detection light 80. The positions of the object light 71 and the reference light 72 thus made can be controlled to desired positions.

  FIG. 5 is a schematic configuration diagram illustrating a configuration example of the optical system 30 provided in the optical pickup 3. In the figure, reference numeral 301 denotes a laser serving as a light source. Reference numeral 302 denotes a lens such as a collimator lens, which converts light emitted from the laser 301 into parallel rays. A beam splitter 303 transmits and reflects light transmitted through the lens 302 in accordance with transmission / reflection characteristics. A polarizing beam splitter 304 transmits P-polarized light (vibration direction is parallel to the incident surface) and reflects S-polarized light (vibration direction is perpendicular to the incident surface).

  Reference numeral 305 denotes a half-wave plate that emits light by rotating the polarization plane of incident light. Reference numeral 306 denotes deflection means, which includes a beam splitter 306a and a deflection surface 306b. A spatial light modulator 307 adds two-dimensional data to the transmitted light. Reference numeral 308 denotes a half-wave plate. A composite polarization beam splitter 309 includes polarization beam splitters 309a and 309b. Reference numeral 310 denotes an objective lens that collects object light and detection light and irradiates the hologram recording medium 1.

  Reference numeral 312 denotes a hologram element having a condensing function. Reference numeral 313 denotes a condensing lens having a condensing function. Reference numeral 314 denotes a two-dimensional light detection array that detects two-dimensional data included in the reflected light of the reference light 72 to which reproduction information is added during reproduction. Reference numeral 315 denotes a condenser lens. Reference numeral 316 denotes a cylindrical lens. Reference numeral 317 denotes a servo light receiving element that detects position information used for position control of the object light 71 and the reference light 72 based on the reflected light of the detection light 80.

  320 is an actuator having a function as the above-described focusing actuator and tracking actuator. The deviation between the object beam 71 and the reference beam 72 is detected as a focus error signal and a track error signal based on the output of the servo light receiving element 317, and the actuator 320 detects a focusing drive signal based on the focus error signal and the track error signal. Based on the tracking drive signal, the objective lens 310 and the hologram element 312 are integrally moved and controlled in the focusing control direction or the tracking control direction.

  The optical system 30 is an optical system based on the peristrolic multiplexing method in which the trajectory of the reference light 72 rotates around the optical axis of the object light 71 so as to draw a cone. In the peritropic multiplexing method, a plurality of pieces of information can be multiplexed and recorded in the same recording area by rotating the reference beam 72. The deflecting unit 306, the objective lens 310, and the hologram element 312 are configured to rotate together.

  The object light 71 is applied to the hologram recording medium 1 as follows. Light emitted from the laser 301 (for example, S-polarized light) is converted into parallel light by the lens 302 and passes through the beam splitter 303. This light is reflected by the polarization beam splitter 304, converted to P-polarized light by the half-wave plate 305, and separated into transmitted light and reflected light by the beam splitter 306a. The light that has passed through the beam splitter 306 a is given two-dimensional data by the spatial light modulator 307, passes through the half-wave plate 308 in the P-polarized state, passes through the polarizing beam splitter 309 a, and passes through the objective lens 310. As the object light 71, the light is condensed near the recording layer 103 in the information recording area 106 of the hologram recording medium 1. The transmission / reflection characteristics of the beam splitter 303 are, for example, 80% transmittance and 20% reflectance (non-polarized light), and the transmission / reflection characteristics of the beam splitter 306a are, for example, 50% transmittance and 50% reflectance (non-polarized light). is there.

  The light reflected by the beam splitter 306a is reflected by the deflecting surface 306b, and is referred to the information recording area 106 irradiated with the object light 71 by the hologram element 312 from the same main surface 108 side as the object light 71. Irradiated as light 72. In the recording layer 103 of the information recording area 106 of the hologram recording medium 1, the object beam 71 and the reference beam 72 interfere with each other, and interference fringes are volume-recorded. The amount of the object light 71 can be arbitrarily set by rotating the half-wave plate 308 around the optical axis. The amount of light may be selected so that the interference fringe pattern is clearest.

  When reproducing the recorded information, the half-wave plate 308 is rotated around the optical axis so that only the S-polarized light component is emitted from the half-wave plate 308. All of this light is reflected by the polarization beam splitter 309a and is not irradiated onto the hologram recording medium 1. As a result, only the P-polarized reference beam 72 is applied to the recording layer 103 of the information recording area 106 where the interference fringes are recorded. This light is diffracted by the recording layer 103 and reflected by the semi-transmissive film layer 101. The reflected light passes through the objective lens 310 and the polarization beam splitter 309a.

  The light that has passed through the beam splitter 306a is converted to S-polarized light by the half-wave plate 308 and passes through the spatial light modulator 307 and the beam splitter 306a. This light is again converted to P-polarized light by the half-wave plate 305, passes through the polarizing beam splitter 304 and the condenser lens 313, and enters the two-dimensional light detection array 314. The two-dimensional photodetection array 314 reproduces two-dimensional data based on this light. When reproducing the recorded data, it is desirable that the spatial light modulator 307 be in a totally transmissive state or removed from the optical path.

  Further, part of the light emitted from the laser 301 and converted into parallel light by the lens 302 is reflected by the beam splitter 303. The S-polarized light is reflected by the polarization beam splitters 309 b and 309 a and enters the objective lens 310. The optical axis of the light incident on the objective lens 310 is set so as to be shifted by a minute angle from the optical axis of the object light 71 by reflection optical components (such as the beam splitter 303, the polarization beam splitters 309b and 309a) in the optical path. . The light condensed by the objective lens 310 enters the control area 107 of the hologram recording medium 1 as detection light 80.

  The light modulated by the concave (convex) portion formed in the control region 107 is reflected by the semi-transmissive film layer 101 and is made into substantially parallel light again by the objective lens 310. This light is reflected by the polarization beam splitters 309 a and 309 b and passes through the beam splitter 303. Subsequently, this light is collected by a condenser lens 315, given astigmatism by a cylindrical lens 316, and enters a servo light receiving element 317. The servo light receiving element 317 detects position information based on this light.

  Next, other irradiation methods of object light, reference light, and detection light according to the present embodiment will be described. FIG. 6 is a schematic reference diagram showing a state in which object light and reference light are irradiated from different main surface sides of the hologram recording medium 1 and detection light is irradiated from one main surface side. The object light 71 and the detection light 81 are applied to the hologram recording medium 1 from the main surface 108 side, and the reference light 72 is applied to the hologram recording medium 1 from the main surface 109 side. The position of the object light 71 is controlled based on control information (information indicated by the focus error signal, the track error signal, and the address signal) generated from the reflected light of the detection light 81, and the reference light 72 is transmitted through the detection light 81. The position is controlled based on control information generated from the light 82. FIG. 7 is a schematic reference diagram showing the above-described irradiation state including the optical systems 31 and 32. The optical system 31 emits object light 71 and detection light 81, and the optical system 32 emits reference light 72.

  FIG. 8 is a schematic reference diagram showing a state when the detection light 83 is irradiated from the main surface 109 side. The object light 71 is irradiated onto the hologram recording medium 1 from the main surface 108 side, and the reference light 72 and the detection light 83 are irradiated onto the hologram recording medium 1 from the main surface 109 side. The position of the object light 71 is controlled based on control information generated from the transmitted light 34 of the detection light 83, and the position of the reference light 72 is controlled based on control information generated from the reflected light of the detection light 83.

  FIG. 9 is a schematic reference diagram showing a state in which object light and reference light are irradiated from different principal surface sides of the hologram recording medium 1 and detection light is irradiated from both principal surface sides. The object light 71 and the detection light 85 are applied to the hologram recording medium 1 from the main surface 108 side, and the reference light 72 and the detection light 86 are applied to the hologram recording medium 1 from the main surface 109 side. The position of the object light 71 is controlled based on control information generated from the reflected light of the detection light 85, and the position of the reference light 72 is controlled based on control information generated from the reflected light of the detection light 86. The detection lights 85 and 86 are applied to the same control region 107 from the opposing main surfaces 108 and 109 side. FIG. 10 is a schematic reference diagram showing the above-described irradiation state including the optical systems 31 and 32. The optical system 31 emits object light 71 and detection light 85, and the optical system 32 emits reference light 72 and detection light 86.

  FIG. 11 is a schematic reference diagram showing a state in which object light and reference light are irradiated from different principal surface sides of the hologram recording medium 1 and detection light is irradiated from both principal surface sides. What is different from the case of FIG. 9 is that the detection light is irradiated to the different control regions 107 from both main surface sides of the hologram recording medium 1. The object light 71 and the detection light 87 are applied to the hologram recording medium 1 from the main surface 108 side, and the reference light 72 and the detection light 88 are applied to the hologram recording medium 1 from the main surface 109 side. The position of the object light 71 is controlled based on control information generated from the reflected light of the detection light 87, and the position of the reference light 72 is controlled based on control information generated from the reflected light of the detection light 88. The detection lights 87 and 88 are applied to the adjacent control area 107 with the information recording area 106 (area to which the object light 71 and the reference light 72 are irradiated) interposed therebetween.

  FIG. 12 is a schematic reference diagram showing the above-described irradiation state including the optical system 31 (object light irradiation means) and 32 (reference light irradiation means). The optical system 31 emits object light 71 and detection light 87, and the optical system 32 emits reference light 72 and detection light 88. In FIG. 12, the optical system 31 that irradiates the object light 71 and the detection light 87 and the optical system 32 that irradiates the reference light 72 and the detection light 88 perform the focusing control direction and tracking control with respect to the hologram recording medium 1. The position is controlled independently in the direction. An arrow A in the figure indicates the focusing control direction, and an arrow B indicates the tracking control direction. Regarding the position control of the optical systems 31 and 32, the entire optical systems 31 and 32 may be moved, or only part of the optical systems 31 and 32 (lenses and the like) may be moved.

  As shown in FIG. 13, only one of the optical systems 31 and 32 may include a light source, and the other may guide light from the light source via an optical fiber 90 or a prism.

  As described above, according to the present embodiment, different recording / reproducing operations are performed by detecting position information using detection light and controlling the irradiation position of object light and reference light on the recording medium based on the position information. Even if there is surface wobbling or eccentricity between apparatuses or recording media, information can be recorded or reproduced at an appropriate recording position in the state of optimal irradiation light on the recording surface. Further, since the control area is irradiated with the detection light without irradiating the information recording area, high-quality recording and reproduction can be performed.

  In addition, when the object light, the reference light, and the detection light are irradiated from the same main surface side of the recording medium (see FIGS. 3 and 4), the above light is irradiated from different main surface sides of the recording medium, respectively. As compared with the optical system, the optical system can be made compact.

  In addition, the object light and the reference light are irradiated from different main surface sides, and the detection light is irradiated from one main surface side (see FIGS. 6 to 8), whereby reflected light and transmitted light of the detection light in the recording medium are transmitted. And the irradiation position of the object light and the reference light can be controlled. Therefore, it is not necessary to irradiate the detection light separately for the object light and the reference light, and the amount of light used for the detection light can be reduced.

  Also, detection light for object light irradiated from the same main surface side as the object light and detection light for reference light irradiated from the same main surface side as the reference light are respectively provided (FIGS. 9 to 9). 13), the optical system related to the object light and the optical system related to the reference light can be separated, and mass productivity is improved. Furthermore, since object light and reference light can be controlled independently, highly accurate control can be performed.

  Further, by irradiating the detection light for object light and the detection light for reference light to different control areas (see FIG. 11), the control signals do not interfere with each other, and high-precision control is performed. Can do.

  Further, by independently controlling the optical system related to the object light and the reference light, the optical system related to the object light and the reference light can be separated (see FIG. 12), and the weight per optical system is reduced. be able to. By reducing the weight of the optical system, it is possible to move to a desired information recording area at a high speed when information is recorded or reproduced, and the access speed can be improved.

  Further, as described in FIG. 5, the object light and the reference light in this embodiment are P-polarized light, and the detection light is S-polarized light. Thus, by making the polarization directions of the object light, the reference light, and the detection light orthogonal, the detection light does not affect information recording. Furthermore, since the reproduction light and the detection light can be separated by the polarizing element, high-quality recording and reproduction can be performed.

  Further, by using the same light source as the light source for the object light, the reference light, and the detection light, it is possible to reduce the size and cost of the apparatus.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes design changes and the like within a scope not departing from the gist of the present invention. It is.

It is a block diagram which shows the structure of the recording / reproducing apparatus by one Embodiment of this invention. FIG. 2 is a cross-sectional structure diagram showing a cross-sectional structure of a hologram recording medium 1 in the same embodiment. It is a schematic reference drawing which shows the mode of irradiation of the object beam, the reference beam, and the detection beam in the same embodiment. It is a schematic reference figure which shows the mode of the irradiation by the optical system 30 in the embodiment. It is a schematic block diagram which shows the structural example of the optical pick-up 3 in the embodiment. It is a schematic reference drawing which shows the mode of irradiation of the object beam, the reference beam, and the detection beam in the same embodiment. It is a schematic reference figure which shows the mode of irradiation by the optical systems 31 and 32 in the embodiment. It is a schematic reference drawing which shows the mode of irradiation of the object beam, the reference beam, and the detection beam in the same embodiment. It is a schematic reference drawing which shows the mode of irradiation of the object beam, the reference beam, and the detection beam in the same embodiment. It is a schematic reference figure which shows the mode of irradiation by the optical systems 31 and 32 in the embodiment. It is a schematic reference drawing which shows the mode of irradiation of the object beam, the reference beam, and the detection beam in the same embodiment. It is a schematic reference figure which shows the mode of irradiation by the optical systems 31 and 32 in the embodiment. In the same embodiment, it is a schematic reference figure which shows the mode of irradiation by the optical systems 31 and 32 at the time of using a single light source.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hologram recording medium, 2 ... Spindle motor, 3 ... Optical pick-up, 4 ... Feed motor, 5 ... Signal processing IC, 6 ... CPU, 7 ... Driver IC, 30, 31, 32 ... optical system, 71 ... object light, 72 ... reference light, 80, 81, 82, 83, 84, 85, 86, 87, 88 ... detection light, 100, 105 ... Substrate, 101 ... Transparent film layer, 102, 104 ... Protective layer, 103 ... Recording layer, 106 ... Information recording area, 107 ... Control area, 108, 109 ... Main surface 301 ... Laser 302 ... Lens 303,306a ... Beam splitter 304,309a, 309b ... Polarizing beam splitter 305,308 ... 1/2 wavelength plate 306 ... Deflection means, 306b .. Deflection surface, 307... Spatial light modulator, 309... Composite polarization beam splitter, 310... Objective lens, 312... Hologram element, 313, 315. Two-dimensional light detection array, 316... Cylindrical lens, 317... Light receiving element for servo, 320.

Claims (8)

Based on the diffracted light of the reference light, irradiating the optical recording medium with object light and reference light, recording the information of the object light on the optical recording medium as interference fringes, irradiating the interference light with the reference light In a recording / reproducing apparatus for reproducing information,
A first irradiating means for irradiating the information recording area on the optical recording medium on which the information is recorded with the object light and the reference light;
Second irradiating means for irradiating detection light for position detection on a control area different from the information recording area on the optical recording medium;
Control means for controlling the irradiation position of the object light and the reference light by the first irradiation means based on the detection result of the position by the detection light;
A recording / reproducing apparatus comprising: The first irradiation means irradiates the object light and the reference light from the first or second main surface side of the optical recording medium,
The recording / reproducing apparatus according to claim 1, wherein the second irradiating unit irradiates the detection light from the main surface side irradiated with the object light and the reference light. The first irradiation means irradiates the object light from one main surface side of the first and second main surfaces, and irradiates the reference light from the other main surface side,
The second irradiation means irradiates the detection light from the first or second main surface side,
In the case where the main surface irradiated with the object light and the main surface irradiated with the detection light are the same, the control means, based on the detection result of the position by the reflected light of the detection light, Control the irradiation position of the object light, and control the irradiation position of the reference light based on the detection result of the position by the transmitted light of the detection light,
When the main surface irradiated with the object light is different from the main surface irradiated with the detection light, the irradiation position of the object light is determined based on the detection result of the position by the transmitted light of the detection light. 2. The recording / reproducing apparatus according to claim 1, wherein the recording and reproducing position is controlled based on a detection result of a position of the detection light reflected by the reflected light. The first irradiation means irradiates the object light from one main surface side of the first and second main surfaces, and irradiates the reference light from the other main surface side,
The second irradiating means irradiates the first detection light from the one main surface side irradiated with the object light and the second detection from the other main surface side irradiated with the reference light. Irradiate light,
The control means controls the irradiation position of the object light based on the position detection result of the reflected light of the first detection light, and based on the position detection result of the reflected light of the second detection light. The recording / reproducing apparatus according to claim 1, wherein an irradiation position of the reference light is controlled.   5. The recording / reproducing apparatus according to claim 4, wherein the second irradiating unit irradiates the control areas with the first detection light and the second detection light, respectively.   The first irradiating means includes object light irradiating means for irradiating the information recording area with the object light and reference light irradiating means for irradiating the information recording area with the reference light. 6. The recording / reproducing apparatus according to claim 4, wherein the irradiation position of the object light by the object light irradiation means and the irradiation position of the reference light by the reference light irradiation means are controlled independently.   The recording / reproducing apparatus according to claim 1, wherein a polarization direction of the object light and the reference light and a polarization direction of the detection light are orthogonal to each other. The recording / reproducing apparatus according to any one of claims 1 to 7, wherein the object light, the reference light, and the detection light are generated by the same light source.

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