JP2009070470A - Optical disk device and tilt adjusting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of cross-talk, and to perform stable servo operation by suppressing a tilt error within a mechanically allowable range, in an optical disk device in which all of focus servo, tracking servo, radial tilt servo, and tangential tilt servo are performed. <P>SOLUTION: An optical disk device 100 is provided with an actuator 110 performing focusing operation of an optical pickup 111, tracking operation, and tilt operation in the radial direction; and a tilt adjusting mechanism 120 performing tilt adjustment of the tangential direction for the optical pickup 11. The tilt adjusting mechanism 120 has an actuator supporting part 130 supporting an actuator 110, and a tilt correcting part 140 performing tilt correction in which a tilt angle formed by a recording plane of an optical disk 5 and a lens plane of the optical pickup 111 is adjusted by rotating an actuator supporting part 130 around a straight line in the radial direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that records and / or reproduces data with respect to an optical disc, and a tilt adjustment mechanism provided in the optical disc apparatus.

  In recent years, a data recording medium is required to have a so-called removable characteristic that allows a medium on which data is recorded to be carried separately from a head for recording and reproducing data. In a data recording medium having such a removable characteristic (hereinafter referred to as “removable recording medium”), data is loaded when it is inserted into a recording / reproducing apparatus and data is recorded and reproduced. In order to perform this loading, it is usually necessary to perform focus servo and tracking servo when the removable recording medium is an optical disk such as a CD or a DVD.

  In the case of an optical disk, a tilt error occurs due to the surface shake of the disk. The tilt error is a deviation (tilt angle) between the spindle direction and the normal direction to the recording surface of the disk. This tilt error occurs when the disc rotation axis does not coincide with the rotation axis of the spindle that rotates the disc, assuming that the disc is a disc-like disc having a perfect plane. When a tilt error occurs, the end of the lens of the optical pickup may come into contact with the recording surface of the optical disc. In this case, the focus servo and tracking servo become unstable.

Therefore, for example, in order to suppress the tilt error within a mechanically acceptable tilt angle range (tilt margin) such that contact between the end of the optical pickup lens and the recording surface of the optical disk can be avoided. A tilt servo that controls the tilt of the optical pickup is also required. In view of such a need, an optical disc apparatus including a so-called triaxial actuator capable of simultaneously performing focus servo, tracking servo, and radial tilt (radial tilt) servo of an optical disc has been proposed (for example, Patent Documents). 1).
JP 2003-317286 A

  Incidentally, the tilt error as described above occurs not only in the radial direction of the optical disc but also in the tangential direction, and it is necessary to perform tilt (tangential tilt) servo in the tangential direction. Therefore, an optical disk device requires a mechanism that can perform all of focus servo, tracking servo, radial tilt servo, and tangential tilt servo.

  However, if tilt servo in both the radial direction and the tangential direction of the optical disk is performed with a single actuator together with the focus servo and tracking servo, problems such as so-called crosstalk occur. This problem of crosstalk is particularly noticeable when a solid immersion lens (SIL) having a high numerical aperture (NA value) is used. That is, when the SIL is used as the lens of the optical pickup, the distance between the lens surface of the optical pickup and the recording surface of the optical disk is as short as about 25 nm, and crosstalk is likely to occur.

  In addition, the optical disc actually does not have a perfect plane as described above, but due to complex factors such as deformation of the disc itself (for example, warpage of the disc) and vibration mode in which the disc inherently vibrates. The disc has a larger tilt angle than when the disc is assumed to be flat. Such deformation and vibration mode of the disc itself are larger in the tangential direction than in the radial direction of the disc, and crosstalk tends to occur.

  Accordingly, the present invention has been made in view of such a problem. In an optical disc apparatus that performs all of focus servo, tracking servo, radial tilt servo, and tangential tilt servo, and a tilt adjustment mechanism provided therein, crosstalk is provided. It is an object of the present invention to prevent the occurrence of the above-described problem and suppress a tilt error within a mechanically acceptable range and perform a stable servo operation.

  In order to solve the above-described problem, according to an aspect of the present invention, an optical pickup for recording and / or reproducing data is mounted in an optical disk apparatus that records and / or reproduces data with respect to an optical disk. An actuator that performs a focusing operation, a tracking operation, and a tilting operation of the optical disc in a radial direction of the optical pickup, and a tilt adjustment mechanism that performs a tilt adjustment of the optical disc in the tangential direction of the optical pickup. The tilt adjustment mechanism includes an actuator support portion that supports the actuator, and the actuator support portion is rotated about a straight line in the radial direction as a rotation axis. The recording surface of the optical disc and the optical pin A tilt correction portion for performing tilt correction of adjusting the tilt angle formed by the lens surface of the backup, the optical disk apparatus having a are provided.

  Here, the tilt correction unit is connected to a fixed unit fixedly installed in the optical disc apparatus, and to the fixed unit so as to be rotatable about a straight line in the radial direction as a rotation axis. A movable part coupled so as to cooperate with a part, and the movable part and the stationary part are installed so as to be inserted through the inside of the movable part and the stationary part. And an operating means for rotating the movable part relative to the fixed part with a connecting part with the movable part as a fulcrum.

  At this time, the connecting portion may be formed of an elastic hinge, and the movable portion may be rotated around the elastic hinge so that a tilt angle in the tangential direction changes.

  Furthermore, the tilt correction unit is connected at both ends to the fixed unit and the movable unit, and the movable unit returns from a state where the movable unit is inclined at a predetermined angle to the tangential direction to a position parallel to the tangential direction. You may have further the elastic body which supplies a restoring force.

  The actuating means may be a piezoelectric element or a magnetostrictive element that deforms in the normal direction of the disk surface.

  The optical pickup may include an objective lens that collects light from a light source and a lens driving unit that drives the objective lens, and a solid immersion lens may be used as the objective lens.

  Moreover, it is preferable that the rotation axis of the movable part passes through the center of the lens surface of the objective lens provided in the optical pickup.

  In order to solve the above-mentioned problems, according to another aspect of the present invention, a focusing operation of an optical pickup for performing data recording and / or reproduction on an optical disc, a tracking operation, and a tilt in the radial direction of the optical disc A tilt adjustment mechanism provided in an optical disc apparatus including an actuator for performing an operation, wherein the actuator support unit supports the actuator on which the optical pickup is mounted, and the actuator support unit is used as a rotation axis on the radial line. A tilt adjustment mechanism that includes a tilt correction unit that performs a tilt correction that adjusts a tilt angle formed between the recording surface of the optical disc and the lens surface of the optical pickup during the recording and / or reproduction of the data by rotating. Is provided.

  As described above, according to the optical disc device and the tilt adjustment mechanism provided in the optical disc device according to the present invention, the actuator support unit coupled to the movable unit is moved in the radial direction by rotating the movable unit with respect to the fixed unit. The straight line is rotated about the rotation axis. Then, the rotation of the actuator support unit causes the optical pickup mounted on the actuator installed in the actuator support unit to be tangential with a radial straight line located at the center of the coupling portion such as an elastic hinge as a rotation axis. The direction can be tilted.

  In addition, according to the optical disk device and the tilt adjustment mechanism provided in the optical disk device according to the present invention, a linearly displacing member such as a piezoelectric element is used as an operating means for rotating the movable part, By using an elastic hinge or the like as the connecting portion, the movable portion (and thus the optical pickup) can be rotated by a minute angle, and precise tilt servo can be performed.

  According to the present invention, in an optical disc apparatus that performs all of focus servo, tracking servo, radial tilt servo, and tangential tilt servo, and a tilt adjustment mechanism provided therein, the tangential tilt servo is replaced with the focus servo, tracking servo, and radial tilt servo. By using a mechanism separate from the actuator that performs the servo, it is possible to prevent the occurrence of crosstalk, suppress the tilt error within a mechanically acceptable range, and perform a stable servo operation.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Necessity of tilt servo)
First, prior to describing an optical disc apparatus according to an embodiment of the present invention, as a premise thereof, the optical axis is always kept perpendicular to the optical disc by electrically detecting warpage of the optical disc and tilt variation during rotation. The necessity of tilt servo for tracking the optical pickup will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing the contents of the tilt error in the radial direction and the tilt error in the tangential direction. FIG. 2 is an explanatory diagram showing a mechanism of tilt generation when the optical disk is assumed to be a perfect plane. FIG. 3 is an explanatory diagram showing the tilt angle when the optical disk is assumed to be a perfect plane. FIG. 4 is an explanatory diagram showing an example of the relationship between the surface shake of the optical disc and the tilt amount. FIG. 5 is an explanatory diagram showing an example of an allowable tilt range when a solid immersion lens is used as the objective lens. FIG. 6 is an explanatory diagram showing an example of the relationship between tilt error and jitter in the case of FIG.

  As shown in FIG. 1, the optical disk 5 as a removable recording medium is rotated by the spindle motor 3 with the spindle axis S of the spindle motor 3 as the rotation axis while being sandwiched between the clamp 1 and the turntable 2. With the optical disk 5 rotating in this way, the laser light emitted from the light source is collected by the objective lens 13 provided in the optical pickup 11, and the collected light is emitted to the recording surface side of the optical disk 5. . The optical pickup 11 is provided with a light receiving portion (not shown), and the light receiving portion receives the reflected light of the laser light irradiated on the recording surface of the optical disc 5 to perform recording and reproduction with respect to the optical disc 5. Is called.

In this manner, loading is performed when data is recorded or reproduced. When this loading is performed, it is necessary to perform focus servo and tracking servo. In addition, when a removable recording medium such as the optical disk 5 is used as the data recording medium, a tilt error occurs due to a surface shake of the optical disk 5 or the like. As shown in FIG. 1, the tilt error includes a tilt error (tilt angle θ ₁ ) in the radial direction R of the optical disc 5 and a tilt error (tilt angle θ ₂ ) in the tangential direction T. Here, the “radial direction” refers to the radial direction of the optical disc 5, and the “tangential direction” refers to the track tangential direction orthogonal to the radial direction of the optical disc 5. The “radial tilt error” refers to the angle θ _{1 in} the radial direction R formed by the flat surface of the lens 13 and the recording surface of the optical disc 5, and “the tilt error in the tangential direction”. The angle θ _{2 in} the tangential direction T formed by the flat surface of the surface of the lens 13 and the recording surface of the optical disk 5 is referred to.

As shown in FIG. 2, when the optical disk 5 is assumed to be a disc-shaped disk having a complete plane, the tilt error of the optical disk 5 is the rotation axis Dd of the optical disk 5 and the spindle that rotates the optical disk 5. This is considered to occur when the rotation axis S does not match and has a predetermined angle θ. That is, in such a case, a radial tilt error θ ₁ and a tangential tilt error θ ₂ as shown in FIG. 1 occur. At this time, for example, in the xyz coordinate space, if the optical disc 5 is represented by the expression “ax + by + cz + d = 0”, the vector hd representing the rotation axis Dd of the optical disc 5 is “hd = (a, b, c)”. The vector hs representing the rotation axis S of the spindle is represented by “hs = (0, 0, 1)”.

  Further, the maximum value and the minimum value of each of the tilting components of the optical disc 5 and the radial and tangential tilt components have a constant period during one rotation of the optical disc 5. Each rotation has a cycle in which there are a maximum value and a minimum value twice. This relationship is shown in FIG. That is, the upper graph in FIG. 3 shows the relationship between the rotation angle of the optical disk 5 and the amount of surface deflection [μm], where 360 deg is when the optical disk 5 rotates once. The lower graph of FIG. 3 shows the relationship between the rotation angle of the optical disk 5 and the tilt angle [deg] in the tangential direction, with 360 deg being when the optical disk 5 makes one rotation. The graph shown in FIG. 3 is an example when it is assumed that the optical disk 5 is a perfect plane.

Here, as shown in FIG. 4, for example, the direction of the recording surface of the optical disc 5 in a state where there is no surface deflection of the optical disc 5 is assumed to be “ _Dial”, and the direction of the recording surface of the optical disc 5 in the state where there is surface deflection of the optical disc 5 D _real , the tilt angle of the optical disk 5 in the tangential direction is θ _a , the surface blur amount of the optical disk 5 is δ _a , the intersection of D _ideal and D _real is C, and the surface blur measurement radius (from the end E of the D _real When the distance) between the intersection and C of the perpendicular and _{D ideal} drawn down to D _ideal to _{r m,} it is derived relationship as equation (1) below.
θ _a = tan ⁻¹ (δ _a / r _m ) (1)

That is, as shown in the equation (1), the tilt angle theta _a can be expressed by a function of the runout [delta] _a. For example, if the tilt angle in the tangential direction shown in FIG. 3 in the case of 0.07Deg, where the runout measurement radius _{r m} and 55mm from the equation (1), the surface vibration of 134μmPP (± 67μm) It corresponds to the amount. In addition, since the reference plane shake amount at the time of servo design is usually 80 μm PP (± 40 μm), in this case, the tilt angle is ± 0.042 deg from equation (1). If the allowable range (tilt margin) is set to ± 0.07 deg, it is within the tilt margin.

  Here, the reference of the tilt margin will be described with reference to FIG. For example, when a solid immersion lens (SIL) is used as the objective lens 13, the diameter D of the distal end portion (front side) of the objective lens 13 as shown in FIG. 5 is about 40 μm. Further, the distance d between the optical disk 5 and the tip of the objective lens 13 is about 25 nm when the distance is maintained by gap servo (equivalent to a focus servo of a general optical disk apparatus). In this case, the maximum tilt angle for preventing the corner of the tip of the objective lens 13 from contacting the optical disc 5 is ± 0.07 ° in both the radial direction and the tangential direction (± 2 (d / D ) [Rad.] ≈ ± 0.07 [deg.]). When the tilt angle is larger than this, the optical disc 5 and the objective lens 13 are in principle in contact with each other, so that the focus servo and tracking servo become unstable. Therefore, when SIL is used as the objective lens 13, the tilt margin is ± 0.07 °, and the relationship between jitter (%) and tilt error (deg) is, for example, as shown in FIG.

  As described above, for example, the tilt error is within a mechanically acceptable tilt angle range (tilt margin) such that contact between the end of the objective lens 13 of the optical pickup and the recording surface of the optical disk 5 can be avoided. In order to suppress this, a tilt servo for controlling the tilt of the optical pickup is also required.

  In particular, when the near-field method using near-field light using a solid immersion lens (SIL) is adopted, the tilt margin becomes narrower than the tilt margin assumed from the quality of the servo signal and the jitter value. A precise tilt servo is required.

  By the way, the tilt error as described above occurs not only in the radial direction of the optical disc 5 but also in the tangential direction, and it is necessary to perform tilt servo in the tangential direction. Therefore, an optical disk device requires a mechanism that can perform all of focus servo, tracking servo, radial tilt servo, and tangential tilt servo.

  However, if tilt servo in both the radial direction and the tangential direction of the optical disk 5 is performed by a single actuator together with the focus servo and tracking servo, problems such as so-called crosstalk occur. This problem of crosstalk is particularly noticeable when a solid immersion lens (SIL) having a large numerical aperture (NA value) is used.

  In addition, the optical disk 5 does not actually have a perfect plane as described above, but due to complex factors such as deformation of the disk itself (for example, warping of the disk) and vibration mode in which the disk vibrates naturally. The tilt angle is larger than that when the disk is assumed to be flat. Such deformation and vibration mode of the disc itself are larger in the tangential direction than in the radial direction of the disc, and crosstalk tends to occur.

  Therefore, in the optical disk apparatus according to the first and second embodiments of the present invention described below, all of the focus servo, tracking servo, radial tilt servo and tangential tilt servo are performed at the same time, and each servo is independent. Therefore, the tangential tilt is adjusted using a mechanism separate from other servos. As a result, according to the optical disk device according to the first and second embodiments of the present invention, the occurrence of crosstalk is prevented, and the tilt error is suppressed within a mechanically acceptable range, thereby achieving stable servo operation. Can be performed. Hereinafter, the overall configuration of the optical disc apparatus 100 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 7 is a perspective view showing the overall configuration of the optical disc apparatus 100 according to the present embodiment.

(First embodiment)
<Configuration of Optical Disc Device 100>
As shown in FIG. 7, the optical disk apparatus 100 is an apparatus for recording and / or reproducing data on an optical disk, and includes a clamp 101, a spindle motor 103, an actuator 110, and a tilt adjustment mechanism 120. Prepare mainly.

  The clamp 101 holds the optical disc 5 together with a turntable (not shown). Further, the spindle motor 103 has a clamp 101 attached to its tip, and rotates the optical disc 5 held by the clamp 101 at a high speed with the spindle axis as a rotation axis. The clamp 101 and the spindle motor 103 are provided on a spindle support member 104.

  The actuator 110 is mounted with an optical pickup 111 that records and / or reproduces data with respect to the optical disc by irradiating the recording surface of the optical disc 5 with laser light and receiving reflected light from the recording surface. Yes. The actuator 110 performs a focusing operation, a tracking operation, and a tilting (radial tilt) operation of the optical disc 5 in the radial direction.

  In addition, since a known technique can be used for the operation mechanism of the focusing operation, the tracking operation, and the radial tilt operation by the actuator 110 (for example, JP-A-2005-332449, JP-A-2007-35160, etc.) The detailed description is omitted here. The actuator 110 is guided by a tracking guide rail 131 provided on an actuator support member 130 described later, and can move in the tracking direction along the tracking guide rail 131.

  The optical pickup 111 generally includes an objective lens 113 that collects light from a light source, and a lens driving unit (not shown) that drives the objective lens 113. For example, a solid immersion lens (SIL) is used as the objective lens 113. Moreover, as a lens drive part, a voice coil motor (VCM) etc. can be used, for example. When the SIL is used as the objective lens 113, a near-field method using near-field light is adopted, and as described above, the tip (surface) of the objective lens 113 and the recording surface of the optical disc 5 are close to each other. Position. Therefore, when the tilt operation of the optical pickup 111 is performed, the corner portion of the tip of the objective lens 113 and the recording surface of the optical disk 5 are likely to come into contact with each other, and a more precise tilt operation is required. Therefore, if the actuator 110 tries to perform two axes in the radial direction and the tangential direction at the same time, the problem of crosstalk tends to occur. Therefore, the optical disc apparatus 100 according to the present embodiment performs a tangential tilt operation by a tilt adjustment mechanism 120 described below.

  The tilt adjustment mechanism 120 is a mechanism that performs tilt adjustment in the tangential direction of the optical disc 5 with respect to the optical pickup 111, and includes an actuator support portion 130 and a tilt correction portion 140.

  The actuator support part 130 is, for example, a substantially plate-like member, and supports the actuator 110 installed on the actuator support part 130. On the actuator support portion 130, a tracking guide rail 131 is provided as a rail-like member parallel to the tracking direction (Y-axis direction in FIG. 7). The guide rail 131 guides the movement of the actuator 110 installed on the actuator support member 130 in the tracking direction. One end of the actuator support 130 is connected to a movable part 141 of a tilt correction unit 140, which will be described later, and the actuator support 130 rotates (tanger) using a straight line in the radial direction of the movable part 141 as a rotation axis. In association with the tilting operation in the local direction), the rotation is performed with the straight line in the radial direction as the rotation axis in cooperation with the operation of the movable portion 141.

  The tilt correction unit 140 rotates the actuator support unit 130 about a straight line in the radial direction as a rotation axis, thereby recording the recording surface of the optical disc 5 and the lens of the objective lens 113 of the optical pickup 111 during data recording and / or reproduction. Tilt correction is performed to adjust the tilt angle between the surface and the surface.

<Configuration of tilt correction unit 140>
Here, a detailed configuration of the tilt correction unit 140 according to the present embodiment will be described with reference to FIGS. 7 and 8. FIG. 8 is a front view showing the configuration of the tilt correction unit 140 according to this embodiment.

  As shown in FIGS. 7 and 8, the tilt correction unit 140 mainly includes a fixed unit 141, a movable unit 143, and a piezoelectric element 145.

  The fixing unit 141 is a substantially rectangular parallelepiped member, for example, and is fixedly installed in the optical disc apparatus 100. More specifically, for example, as shown in FIG. 7, the fixed portion 141 is opposite to the side on which the optical disk 5 is installed by the fixed portion support member 107 connected to the servo mechanism support base 105 via the connection member 109. It is fixed in the optical disc apparatus 100 by being supported from the side (Y-axis negative direction in FIG. 7). Further, as shown in FIG. 8, a fixed portion side piezoelectric element mounting portion 141 a for inserting a piezoelectric element 145 described later is formed in the fixed portion 141. For example, when the piezoelectric element 145 has a rod shape, the fixed portion side piezoelectric element mounting portion 141 a is formed in a shape like a through hole having a cross section larger than that of the piezoelectric element 145.

  The movable portion 143 is, for example, a substantially rectangular parallelepiped member, and is rotatably connected to the fixed portion 141 with a straight line in the radial direction as a rotation axis. That is, for example, the movable portion 143 has an upper surface side (the Z-axis positive direction side in FIGS. 7 and 8) connected to the fixed portion 141 via a connecting portion 147 as shown in FIG. With the direction straight line 147a as a rotation axis, it can be rotated so as to be inclined at a predetermined angle from the tangential direction. A movable region 147b is formed between the movable portion 143 and the fixed portion 141, and the movable portion 143 rotates within the movable region 147b.

  Further, the movable portion 143 has a front side (Y-axis positive direction side in FIG. 7) connected to the actuator support portion 130, and the movable portion 143 and the actuator 130 are connected by an operating means such as a piezoelectric element 145 described later. Can rotate in cooperation. In the present embodiment, the movable portion 143 is configured as a separate member from the actuator support portion 130, but is not limited to this case. For example, the movable part 143 may be configured integrally with the actuator support part 130. That is, the actuator support part 130 itself may be a movable part and may be connected to the fixed part 141 via the connection part 147.

  Further, as shown in FIG. 8, a movable part side piezoelectric element mounting part 143 a for inserting a piezoelectric element 145 described later is formed in the movable part 143. For example, when the piezoelectric element 145 has a rod shape, the movable portion side piezoelectric element mounting portion 143a is formed in a shape like a through hole having a cross section larger than that of the piezoelectric element 145.

  The piezoelectric element 145 is an example of an operation unit according to the present embodiment, and is an element formed of a piezoelectric ceramic material such as lead zirconate titanate (PZT). The piezoelectric element 145 is linear with a displacement of about 0 to 40 μm in the normal direction (Z-axis direction in FIGS. 7 and 8) of the disk surface of the optical disk 5 by applying a voltage of about 0 to 150 V, for example. Deforms. Further, the piezoelectric element 145 is inserted into the fixed part side piezoelectric element mounting part 141a and the movable part side piezoelectric element mounting part 143a in a preloaded state. Then, by increasing the applied voltage to the piezoelectric element 145 from this pre-loaded state, the piezoelectric element 145 is displaced in the extending direction (Z-axis negative direction in FIG. 8), and by decreasing the applied voltage to the piezoelectric element 145, The piezoelectric element 145 is displaced in the contracting direction (Z-axis positive direction in FIG. 8).

  The piezoelectric element 145 is installed so as to pass through the inside of the fixed portion 141 and the movable portion 143, and is displaced in the normal direction of the disk surface of the optical disc 5, thereby connecting the fixed portion 141 and the movable portion 143. The movable part 143 is rotated with respect to the fixed part 141 with fulcrum as a fulcrum. Further, the maximum angle of rotation of the movable portion 143, and hence the maximum tilt angle of the optical pickup 111, is the installation position of the piezoelectric element 145, that is, the fixed portion side piezoelectric element mounting portion 141a and the movable portion side piezoelectric element mounting portion 143a. By adjusting the distance of the formation position from the rotation shaft 147a, it can be designed to have a desired maximum tilt angle. The details of the rotating operation of the movable portion 143 by the piezoelectric element 145 will be described later.

  The operation means in the present invention is not limited to the above-described piezoelectric element 145, and any one that can be deformed in the normal direction of the disk surface of the optical disk 5 can be used. In addition, a magnetostrictive element or the like can also be used. In addition to these, a voice coil motor (VCM) or the like can be used as the operating means. However, in piezoelectric elements using PZT, etc., the force generated by voltage application is large and the response of the force generation is fast. However, VCM has a small force generated by voltage application and a large number of coil turns. Then, it generates heat and power consumption increases. Therefore, it is preferable to use a piezoelectric element or a magnetostrictive element rather than VCM as the actuating means in the present invention, and the piezoelectric element is most preferable from the viewpoint of the generated force and the speed of response.

  In the present embodiment, the connecting portion 147 is formed of an elastic hinge having an arc-shaped cutout portion formed of a material such as an elastomer, for example. Then, when the operating means such as the piezoelectric element 145 is displaced in the normal direction of the optical disc 5, the movable portion 143 rotates so that the tilt angle in the tangential direction changes with the elastic hinge as the central axis. Can do. In general, the elastic hinge has the advantages that it can improve positioning accuracy because there is no stick-slip due to friction, and can increase the moving speed with less heat generation. Therefore, by using an elastic hinge as the connecting portion 147, the response of the tangential tilt operation of the movable portion 143 to the displacement of the operating means such as the piezoelectric element 145 can be accelerated.

  In addition, the tilt correction unit 140 may further include an elastic body 149. As the elastic body 149 in the present invention, for example, a member that linearly displaces by a predetermined elastic force such as a coil spring or a leaf spring as indicated by a broken line in FIG. 8 can be used. Further, as shown in FIG. 8, for example, both ends of the elastic body 149 are connected to the fixed portion 141 and the movable portion 143 on the side opposite to the piezoelectric element 145 with respect to the connecting portion 147. The elastic body 149 supplies a restoring force for returning the movable portion 143 from a state inclined by a predetermined angle with respect to the tangential direction to a position parallel to the tangential direction. That is, when the piezoelectric element 145 is displaced in the normal direction of the optical disc 5 (for example, the negative Z-axis direction), the elastic body 149 is displaced in the direction opposite to the piezoelectric element 145 (for example, the positive Z-axis direction). The elastic body 149 has a restoring force in the same direction as the direction of displacement of the piezoelectric element 145 (that is, the direction of the force applied to the movable part 143 by the piezoelectric element 145), and the rotating part 143 is rotated by this restoring force. To assist.

<Operation of Tilt Correction Unit 140>
Next, the operation of the tilt correction unit 140 according to the present embodiment having the above-described configuration will be described with reference to FIG. FIG. 9 is a front view showing the operation of the tilt correction unit 140 according to the present embodiment.

  First, as shown in FIG. 9A, when the voltage applied to the piezoelectric element 145 is increased from the state where the movable portion 143 is located in a position parallel to the tangential direction, the state shown in FIG. Thus, the piezoelectric element 145 is displaced in the extending direction (downward in FIG. 9). When the piezoelectric element 145 is displaced in this way, the lower end portion of the piezoelectric element 145 presses the bottom of the movable part side piezoelectric element mounting part 143a downward, and faces downward to the bottom part of the movable part side piezoelectric element mounting part 143a of the movable part 143. The power of is added. Here, in the present embodiment, the movable portion side piezoelectric element mounting portion 143a is formed on the right side of the connecting portion 147. Therefore, due to the downward force applied to the movable portion 143 by the piezoelectric element 145, the movable portion 143 rotates a straight line 147a in the radial direction passing through the central portion of the connecting portion 147 with the connecting portion 147 as a fulcrum. As a moving axis, it rotates clockwise so as to be inclined at a predetermined angle with respect to the tangential direction (state shown in FIG. 9B). At this time, although not shown in FIGS. 9A to 9C, when the elastic body 149 described above is present, the elastic body 149 is contracted by the clockwise rotation of the movable portion 143 ( 9 is displaced upward, and has a restoring force in a direction opposite to the displaced direction (downward in FIG. 9).

  Next, when the voltage applied to the piezoelectric element 145 is decreased from the state shown in FIG. 9B, the piezoelectric element 145 is displaced in the contracting direction (upward in FIG. 9). When the piezoelectric element 145 is displaced in this way, the downward force applied to the bottom of the movable part side piezoelectric element mounting part 143a is not applied. Therefore, when the connecting part 147 is an elastic hinge, due to the elastic force, The movable part 143 rotates counterclockwise with the connecting part 147 as a fulcrum, and returns to the state of FIG. At this time, since the force for rotating the movable portion 143 is weak with the elastic force of only the elastic hinge and the rotation speed (response) is slow, it is preferable that the elastic body 149 is provided. In this case, the elastic body 149 has a downward restoring force as described above. Therefore, since the downward force is applied to the left side of the connecting portion 147 of the movable portion 143 by this restoring force, the counterclockwise rotation of the movable portion 143 can be assisted, and thereby the rotation of the movable portion 143 can be assisted. It is possible to increase the dynamic speed (response).

  Furthermore, when the voltage applied to the piezoelectric element 145 is decreased from the state shown in FIG. 9A, the piezoelectric element 145 is displaced in the contracting direction (upward in FIG. 9). When the piezoelectric element 145 is displaced in this way, the downward force applied to the bottom of the movable part side piezoelectric element mounting part 143a is not applied. Therefore, when the connecting part 147 is an elastic hinge, due to the elastic force, The movable portion 143 uses the connecting portion 147 as a fulcrum, and more specifically, uses a radial straight line 147a passing through the central portion of the connecting portion 147 as a rotation axis so as to incline at a predetermined angle with respect to the tangential direction. It rotates around (state shown in FIG. 9C). At this time, although not shown in FIGS. 9A to 9C, when the above-described elastic body 149 exists, the elastic body 149 extends in the counterclockwise rotation of the movable portion 143. It is displaced in the downward direction (in FIG. 9) and has a restoring force in a direction opposite to the displaced direction (in the upward direction in FIG. 9). In addition, about the effect | action of the restoring force of the elastic body 149 when returning to the state of Fig.9 (a) from the state of FIG.9 (c), when returning to the state of Fig.9 (a) from the state of FIG.9 (b) Is the same principle.

  As described above, when the movable portion 143 rotates with respect to the fixed portion 141, the actuator support portion 130 connected to the movable portion 143 rotates about the radial straight line as the rotation axis. The rotation of the actuator support 130 causes the optical pickup 111 mounted on the actuator 110 installed on the actuator support 130 to rotate the radial straight line 147a positioned at the center of the connecting portion 147 such as an elastic hinge. A tilting operation in the tangential direction can be performed as a moving axis.

  Further, a linearly displacing member such as a piezoelectric element 145 is used as an operating means for rotating the movable portion 143, and an elastic hinge or the like is used as the connecting portion 147 serving as the rotation center of the movable portion 143. The unit 143 (and thus the optical pickup 111) can be rotated by a minute angle, and precise tilt servo can be performed. Further, the maximum angle at this time can be designed to be a desired maximum angle as appropriate based on the amount of displacement of the piezoelectric element 145, the stress of the elastic hinge, and the like.

(Modification of the first embodiment)
Next, a modified example of the optical disc device 100 according to the first embodiment of the present invention will be described. In the optical disc apparatus according to this modification, the objective lens 113 is installed so that the rotation shaft 147a of the movable portion 143 passes through the center of the lens surface of the objective lens 113 provided in the optical pickup 111.

<Configuration of Tilt Correction Unit 140 According to Modification of First Embodiment>
Hereinafter, the configuration of the tilt correction unit 140 according to this modification will be described with reference to FIGS. 10 and 11. FIG. 10 is an explanatory diagram showing the positional relationship between the rotation shaft 147a of the movable portion 143 and the center C of the tip portion (surface) of the objective lens 113 according to this modification. FIG. 11 is a front view showing the configuration of the tilt correction unit 140 according to this modification.

  First, as shown in FIG. 10B, the optical pickup 111 including the objective lens 113 is simply tilted in the tangential direction. For example, the rotation center C ′ of the tilt operation is the tip of the objective lens 13. Does not match, the irradiation direction of the laser light from the light source collected by the objective lens 13 greatly changes with the tilting operation. As described above, when the laser beam irradiation direction changes greatly, the laser beam irradiation position on the recording surface of the optical disk 5 may change greatly in the focusing direction or the tracking direction. It may be a disturbance factor.

  Therefore, in this modified example, the objective lens 113 is installed so that the rotation shaft 147a of the movable portion 143 passes through the center of the lens surface of the objective lens 113 provided in the optical pickup 111. With such a configuration, as shown in FIG. 10A, the objective lens 113 according to this modification example has a radial direction passing through the center position C of the tip of the objective lens 113 with respect to the recording surface of the optical disc 5. Rotation (tilt operation) can be performed with a straight line as a rotation axis. That is, as shown in FIG. 11, in the tilt correction unit 140 according to this modification example, the movable unit 143 has a radial straight line passing through the center position C of the distal end portion of the objective lens 113 at the center position of the connecting unit 147. This coincides with the rotation shaft 147a.

  As described above, in this modification example, the straight line in the radial direction passing through the center position C of the distal end portion of the objective lens 113 and the rotation shaft 147a of the movable portion 143 at the center position of the connecting portion 147 are matched. It is possible to suppress a change in the irradiation direction of the laser light from the light source collected by the objective lens 13 with the tilting operation. Therefore, the irradiation position of the laser beam on the recording surface of the optical disk 5 is not greatly changed in the focusing direction or the tracking direction due to the tilt operation of the objective lens 113. Therefore, the tilt servo operation is a disturbance factor of the focus servo or tracking servo. The possibility of becoming can be avoided.

  Note that the other configuration of the tilt correction unit 140 according to the present modification example is the same as that of the tilt correction unit 140 according to the first embodiment described above, and a description thereof will be omitted.

<Operation of Tilt Correction Unit 140 According to Modified Example of First Embodiment>
Next, the operation of the tilt correction unit 140 according to this modification example having the above-described configuration will be described with reference to FIG. FIG. 12 is a front view showing the operation of the tilt correction unit 140 according to this modification.

  First, as shown in FIG. 12A, when the voltage applied to the piezoelectric element 145 is increased from the state where the movable portion 143 is located in a position parallel to the tangential direction, the state shown in FIG. Thus, the piezoelectric element 145 is displaced in the extending direction (downward in FIG. 12). When the piezoelectric element 145 is displaced in this way, the lower end portion of the piezoelectric element 145 presses the bottom of the movable part side piezoelectric element mounting part 143a downward, and faces downward to the bottom part of the movable part side piezoelectric element mounting part 143a of the movable part 143. The power of is added. Here, in this modified example, the movable part side piezoelectric element mounting part 143 a is formed on the right side of the connecting part 147. Therefore, the downward force applied to the movable part 143 by the piezoelectric element 145 causes the movable part 143 to rotate clockwise so as to be inclined at a predetermined angle with respect to the tangential direction with the connecting part 147 as a fulcrum (see FIG. 12 (b) state). At this time, the objective lens 113 of the optical pickup (not shown) tilts clockwise as the actuator support portion (not shown) connected to the movable portion 143 rotates. The rotation axis of the tilt, that is, the radial straight line passing through the center position C of the tip of the objective lens 113, and the rotation axis 147a of the movable part 143 at the center position of the connecting part 147 remain in alignment. The objective lens 113 performs a tilt operation.

  Next, when the voltage applied to the piezoelectric element 145 is decreased from the state shown in FIG. 12B, the piezoelectric element 145 is displaced in the contracting direction (upward in FIG. 12). When the piezoelectric element 145 is displaced in this way, the downward force applied to the bottom of the movable part side piezoelectric element mounting part 143a is not applied. Therefore, when the connecting part 147 is an elastic hinge, due to the elastic force, The movable part 143 rotates counterclockwise with the connecting part 147 as a fulcrum, and returns to the state of FIG. Also at this time, the tilt rotation axis of the objective lens 113, that is, the radial straight line passing through the center position C of the tip of the objective lens 113, and the rotation axis 147a of the movable portion 143 at the center position of the connecting portion 147. The objective lens 113 performs a tilting operation in a state where and match.

  Further, when the voltage applied to the piezoelectric element 145 is decreased from the state shown in FIG. 12A, the piezoelectric element 145 is displaced in the contracting direction (upward in FIG. 12). When the piezoelectric element 145 is displaced in this way, the downward force applied to the bottom of the movable part side piezoelectric element mounting part 143a is not applied. Therefore, when the connecting part 147 is an elastic hinge, due to the elastic force, The movable part 143 rotates counterclockwise so as to be inclined at a predetermined angle with respect to the tangential direction with the connecting part 147 as a fulcrum (state shown in FIG. 12C). Also at this time, the tilt rotation axis of the objective lens 113, that is, the radial straight line passing through the center position C of the tip of the objective lens 113, and the rotation axis 147a of the movable portion 143 at the center position of the connecting portion 147. The objective lens 113 performs a tilting operation in a state where and match.

  As described above, when the movable portion 143 rotates, the radial straight line passing through the center position C of the tip portion of the objective lens 113 and the rotation shaft 147 a of the movable portion 143 at the center position of the connecting portion 147. The objective lens 113 can perform a tilting operation while always matching. That is, the objective lens 113 can always perform a tilting operation using a radial straight line passing through the center position C of the tip of the objective lens 113 as a rotation axis. Therefore, according to this modification, the tilt servo operation is focused. The possibility of becoming a disturbance factor of the servo and tracking servo can be avoided.

  Since other operations of the tilt correction unit 140 according to this modification example are the same as those of the tilt correction unit 140 according to the first embodiment described above, description thereof will be omitted.

(Tilt servo method)
Next, a tilt servo method in the optical disc apparatus according to the first embodiment of the present invention and a modified example thereof (hereinafter referred to as “this embodiment”) will be described with reference to FIGS. 13 and 14. FIG. 13 is a block diagram illustrating a functional configuration for realizing the tilt servo according to the present embodiment, and FIG. 14 is an explanatory diagram illustrating an example of a result of tilt correction to which the tilt servo method according to the present embodiment is applied. It is.

  As shown in FIG. 13, as a functional configuration for realizing the tilt servo method according to the present embodiment, the optical disc apparatus according to the present embodiment includes a tilt control unit 161, a tilt adjustment unit 163, an optical system 165, and a tilt. And a detection unit 167.

  The tilt control unit 161 performs the tilt operation of the optical pickup 111 on the tilt adjustment unit 163 in accordance with the tilt error detected by the tilt detection unit 167, that is, the tilt angle formed between the normal direction of the optical disc 5 and the spindle axis. Command.

  The tilt adjustment unit 163 controls the operation of the tilt adjustment mechanism 120 based on a command from the tilt control unit 161. Specifically, for example, the tilt adjustment unit 163 determines a voltage to be applied to the piezoelectric element 145 based on a command from the tilt control unit 161. The tilt adjustment unit 163 notifies the optical system 165 of the adjusted tilt angle.

  The optical system 165 generates a tilt error signal indicating the magnitude of the tilt error based on the adjusted tilt angle notified from the tilt adjusting unit 163. The generated tilt error signal is supplied to the tilt detector 167 and other processing units.

  The tilt detector 167 detects a tilt error based on the tilt error signal generated by the optical system 165. Further, the tilt detection unit 167 converts the detected tilt error into a voltage value and feeds it back to the tilt control unit 161. Note that the tilt detection unit 167 may refer to the tilt angle after adjustment by the tilt adjustment unit 163 when detecting a tilt error.

  An example of the result of tilt correction servo-controlled by the signal processing unit as described above is shown in FIG. In FIG. 14, the “input signal to the PZT driver” is a signal input to the PZT driver that applies a voltage to a piezoelectric element such as PZT, and the “tan GESPP signal” It means a tilt error signal measured through a method of detecting a tilt using a difference between signals of a 4-part PD.

  As shown in FIG. 14, according to the servo method according to the present embodiment, when the control by the tilt control unit 161 is started, the tilt error becomes very small, and stable tilt servo is possible.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, the case where the tilt correction unit 140 includes the fixed unit 141, the movable unit 143, and the operation unit (piezoelectric element 145) has been described. However, the configuration of the tilt correction unit 140 is the above-described configuration. Not limited.

  For example, in the embodiment described above, the case where an elastic hinge is applied to the connecting portion 147 has been described as an example, but a plate spring or the like may be used in addition to the elastic hinge.

It is explanatory drawing which shows the content of the tilt error of a radial direction, and the tilt error of a tangential direction. It is explanatory drawing which shows the mechanism of the tilt generation | occurrence | production when an optical disk is assumed to be a perfect plane. It is explanatory drawing which shows the tilt angle at the time of assuming that an optical disk is a perfect plane. It is explanatory drawing which shows an example of the relationship between the surface shake of an optical disk, and the amount of tilts. It is explanatory drawing which shows an example of the tolerance | permissible_range of a tilt at the time of using a solid immersion lens as an objective lens. FIG. 6 is an explanatory diagram showing an example of a relationship between tilt error and jitter in the case of FIG. 5. 1 is a perspective view showing an overall configuration of an optical disc apparatus according to a first embodiment of the present invention. It is a front view which shows the structure of the tilt correction part which concerns on the same embodiment. It is a front view which shows operation | movement of the tilt correction part which concerns on the same embodiment. It is explanatory drawing which shows the positional relationship of the rotational axis of the movable part which concerns on the example of a change of the embodiment, and the center of the front-end | tip part (surface) of an objective lens. It is a front view which shows the structure of the tilt correction part which concerns on the example of a change. It is a front view which shows operation | movement of the tilt correction part which concerns on the example of a change. It is a block diagram which shows the function structure for implement | achieving the tilt servo which concerns on the said embodiment and the said modification. It is explanatory drawing which shows an example of the result of the tilt correction | amendment which applied the tilt servo method which concerns on the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical disk apparatus 110 (3-axis) actuator 111 Optical pick-up 113 Solid immersion lens (SIL)
120 Tilt adjustment mechanism 130 Actuator support member 131 Tracking guide rail 140 Tilt correction part 141 Movable part 143 Fixed part 145 PZT
147 Elastic hinge 149 Spring 161 Tilt control unit 163 Tilt adjustment unit 165 Optical system 167 Tilt detection unit

Claims (8)

In an optical disc apparatus for recording and / or reproducing data on an optical disc,
An optical pickup for recording and / or reproducing the data, and an actuator for performing a focusing operation, a tracking operation, and a radial tilt operation of the optical disc;
A tilt adjustment mechanism that performs tilt adjustment in the tangential direction of the optical disc with respect to the optical pickup;
With
The tilt adjustment mechanism includes:
An actuator support for supporting the actuator;
The tilt angle formed by the recording surface of the optical disc and the lens surface of the optical pickup during the recording and / or reproduction of the data is adjusted by rotating the actuator support portion about the radial straight line as a rotation axis. A tilt correction unit for performing tilt correction, and
An optical disc apparatus comprising: The tilt correction unit is
A fixing unit fixedly installed in the optical disc device;
A movable portion coupled to the fixed portion so as to be rotatable about a straight line in the radial direction as a rotation axis, and coupled to cooperate with the actuator support portion;
The movable portion is installed so as to be inserted through the movable portion and the fixed portion, and is displaced in the normal direction of the disk surface of the optical disc, whereby the movable portion is configured with the connecting portion of the fixed portion and the movable portion as a fulcrum. An operating means for rotating with respect to the fixed portion;
The optical disc apparatus according to claim 1, wherein The connecting portion is composed of an elastic hinge,
The optical disk apparatus according to claim 2, wherein the movable portion rotates about the elastic hinge so as to change a tilt angle in the tangential direction.   The tilt correcting unit is connected to the fixed unit and the movable unit at both ends, and the restoring force for returning the movable unit from a state inclined at a predetermined angle with respect to the tangential direction to a position parallel to the tangential direction. The optical disk apparatus according to claim 3, further comprising an elastic body for supplying the optical disk.   4. The optical disk apparatus according to claim 3, wherein the actuating means is a piezoelectric element or a magnetostrictive element that is deformed in a normal direction of the disk surface. The optical pickup includes an objective lens that collects light from a light source, and a lens driving unit that drives the objective lens,
The optical disk apparatus according to claim 1, wherein a solid immersion lens is used as the objective lens.   The optical disc apparatus according to claim 2, wherein a rotation axis of the movable part passes through a center of a lens surface of an objective lens provided in the optical pickup. A tilt adjustment mechanism provided in an optical disc apparatus provided with an actuator for performing a focusing operation, a tracking operation, and a radial tilt operation of the optical disc for recording and / or reproducing data on the optical disc,
An actuator support for supporting the actuator with the optical pickup mounted thereon;
The tilt angle formed by the recording surface of the optical disc and the lens surface of the optical pickup during the recording and / or reproduction of the data is adjusted by rotating the actuator support portion about the radial straight line as a rotation axis. A tilt correction unit for performing tilt correction, and
A tilt adjustment mechanism comprising:

Images