JP4169753B2 - Optical element driving device - Google Patents

Description

  The present invention relates to a drive device for driving an optical element such as an objective lens in an apparatus for recording or reproducing information on an information recording medium such as a DVD (Digital Versatile Disc) recorder.

  In recent years, development of optical disc apparatuses that can handle a plurality of types of optical discs has been underway. In such an optical disc apparatus, since it is necessary to form an appropriate light spot according to the type of the optical disc, a plurality of objective lenses are switched and used depending on the type of the optical disc. Switching of the objective lens is performed by sliding the entire objective lens driving device equipped with a plurality of objective lenses in the tracking direction (see, for example, Patent Document 1).

JP-A-9-81947 (1-8 Mitsugu, Fig. 1-6)

  However, in the conventional configuration described above, when switching the objective lens, not only the lightweight objective lens and lens holder, but also the heavy components (support rod and fixed portion) are moved in the tracking direction. There is a problem that a large driving force is required and a large-scale device is required.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical element driving apparatus capable of switching optical elements with a small driving force.

An optical element driving apparatus according to the present invention includes a holder for holding two switchable optical elements for condensing light on a recording medium, elastically deformable support means for supporting the holder, and the holder as the optical element. Focusing driving means for driving in the optical axis direction and tracking driving means for driving the holder in a tracking direction substantially orthogonal to the optical axis direction, and moving the holder by the tracking driving means, An optical element driving apparatus for switching the optical element for condensing light on a medium , wherein the tracking driving means selects a coil fixed to the holder and one of the two optical elements First and second magnets arranged side by side in the tracking direction so as to face each of the coils. A third magnet disposed on the opposite side of the first and second magnets so as to face the coil even when these optical elements are selected. The optical element is held at a position for condensing light on the recording medium by a magnetic interaction between the provided magnetic body and the first, second, or third magnet .

  According to the present invention, the optical element can be switched by moving the holder in which the optical element (for example, an objective lens) is mounted in the tracking direction using the tracking drive unit. Therefore, there is no need to move a heavy component, and the optical element can be switched with a simple configuration. Since it is not necessary to provide a dedicated mechanism for switching the optical elements, an inexpensive and small optical element driving device can be obtained.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing an optical element driving apparatus according to Embodiment 1 of the present invention, and shows a state where one of two optical elements is selected. 2A, 2B, and 2C are a front view, a side view, and a plan view, respectively, showing the optical element driving device shown in FIG. FIG. 3 is a perspective view showing a state where the optical element driving apparatus shown in FIG. 1 has selected the other optical element. 4A, 4B, and 4C are a front view, a side view, and a plan view, respectively, corresponding to FIG. FIG. 5 is a perspective view showing the optical element driving apparatus shown in FIG. 1 divided into a movable part and a fixed part. 6 is an exploded perspective view showing a movable part of the optical element driving apparatus shown in FIG.

  As shown in FIG. 1, the optical element driving apparatus according to the present embodiment is elastically supported by a base 101, a support base 102 provided on the base 101, and a wire (described later) on the support base 102. A lens holder 106 having a substantially rectangular parallelepiped shape and objective lenses (optical elements) 104 and 105 held by the lens holder 106 are provided. The objective lenses 104 and 105 are disposed adjacent to each other so that their optical axes are parallel to each other. The lens holder 106 also has the objective lenses 104 and 105 so that the optical axes of the objective lenses 104 and 105 are orthogonal to the recording surface of the optical disk (recording medium) (that is, parallel to the rotation axis of the optical disk). Holding.

  In the following description, the optical axis direction of the objective lenses 104 and 105 (the direction orthogonal to the recording surface of the optical disk) is defined as the Z direction. Further, in the Z direction, the direction approaching the optical disk is defined as the upper direction, and the opposite direction is defined as the lower direction. The direction in which the objective lenses 104 and 105 are arranged, that is, the direction connecting the lens centers of the objective lenses 104 and 105 is defined as the X direction. A direction orthogonal to the X direction and the Y direction is defined as a Y direction. The X direction coincides with the radial direction of the optical disk passing through the centers of the objective lenses 104 and 105. The Y direction coincides with the track direction of the optical disc.

  The objective lenses 104 and 105 collect light with respect to the optical disc, and correspond to different types of optical discs. For example, the objective lens 104 is used for a Blu-ray disc, and the objective lens 105 is used for other methods. The objective lenses 104 and 105 are configured so as to be able to form an optimum beam spot for the optical disk used, and are attached to the objective lenses 104 and 105.

  The base 101 is made of a metal such as a magnetic material. The support base 102 described above is provided on the upper surface of the base 101 and at one end in the Y direction. The base 101 is also formed with a through hole 101e (FIG. 5) through which light incident on the objective lens (104 or 105) passes. The through hole 101e is located near the end of the base 101 opposite to the support base 102 and at the center in the X direction.

  Magnets 103 a and 103 b are arranged at the end of the base 101 opposite to the support base 102. The magnets 103a and 103b are, for example, permanent magnets, have a magnetic pole surface parallel to the XZ plane, and the magnetic pole surface faces the support base 102 side. The magnets 103a and 103b are located on both sides of the center of the base 101 in the X direction.

  On the base 101, a magnet 103c is disposed so as to be positioned between the magnets 103a and 103b and the support base 102. The magnet 103c has a magnetic pole surface parallel to the XZ plane, and the magnetic pole surface faces the magnets 103a and 103b. The magnet 103c is located at the center of the base 101 in the X direction.

  The magnets 103a and 103b and the magnet 103c are arranged so as to sandwich the lens holder 106 in the Y direction. The magnets 103a, 103b, and 103c are attached to fixed walls 101a, 101b, and 101c formed integrally with the base 101, respectively. The fixed walls 101a to 101c are formed, for example, by bending a part of the base 101 on a flat plate.

  As shown in FIGS. 2 and 3, six conductive wires (elastic bodies) 111a, 111b, 111c, 111d, 111e, and 111f are attached to both ends of the lens holder 106 in the X direction. Yes. The wires 111a to 111c are arranged in the Z direction, and each tip end is fixed to a protrusion 106a formed on one end surface in the X direction (a wall surface parallel to the YZ plane) of the lens holder 106, and each end portion is a support base 102. The substrate 112 is fixed to the substrate 112. Similarly, the wires 111d to 111f are arranged in the Z direction, and each distal end portion is fixed to a protrusion 106b formed on the other end surface in the X direction of the lens holder 106 (a wall surface parallel to the YZ plane). It is fixed to the substrate 112. The lens holder 106 is elastically supported with respect to the support base 102 by these wires 111a to 111f.

  Due to the elastic deformation of the wires 111a to 111f, the lens holder 106 can move in the substantially X direction between the position shown in FIG. 1 and the position shown in FIG. When the lens holder 106 is in the position shown in FIG. 1, the objective lens 104 is located on the through hole 101 e (FIG. 5) of the base 101. Thereby, information can be recorded on and reproduced from the optical disk by the objective lens 104, or both. When the lens holder 106 is in the position shown in FIG. 3, the objective lens 105 is located on the through hole 101 e (FIG. 5) of the base 101. Thereby, information can be recorded on and reproduced from the optical disk by the objective lens 105, or both.

  As shown in FIG. 6, the focusing coil 107 is fixed so as to surround two wall surfaces parallel to the XZ plane of the lens holder 106 and two wall surfaces parallel to the YZ plane. This focusing coil 107 has a winding axis in the Z direction and is wound in a substantially rectangular shape so that current flows in the X direction and the Y direction.

  The tracking coil 108a is fixed to one wall surface parallel to the XZ plane of the lens holder 106, and the tracking coil 108b is fixed to the other wall surface parallel to the XZ plane of the lens holder 106. Each of the tracking coils 108a and 108b has a winding axis in the Y direction, and is wound in a substantially rectangular shape so that current flows in the X direction and the Z direction.

  The tilt coils 109a and 109b are fixed to the lower surface (wall surface parallel to the XY plane) of the lens holder 106 so as to be adjacent in the X direction. Each of the tilt coils 109a and 109b has a winding axis in the Z direction, and is wound in a substantially rectangular shape so that current flows in the X direction and the Y direction. Further, the winding directions of the tilt coils 109a and 109b are opposite to each other.

  The focusing coil 107, the tracking coils 108a and 108b, and the tilt coils 109a and 109b are electrically connected to the wires 110a to 110f, and a current is supplied via the wires 110a to 110f and the substrate 112. .

  On one wall surface parallel to the XZ plane of the lens holder 106, magnetic pieces 110a and 110b are fixed so as to face the magnets 103a and 103b. Magnetic pieces 110c and 110d are fixed on the other wall surface parallel to the XZ plane of the lens holder 106 so as to face the magnet 103c.

  Next, the operation of the optical element driving device according to this embodiment will be described. First, the case where the objective lens 104 is selected (FIG. 1) will be described. FIGS. 7A, 7B, and 7C are schematic diagrams for explaining focusing control, tracking control, and tilt control, respectively. Note that the magnetic poles (N pole, S pole) and current directions of the magnets 103b and 103c shown in FIGS. 7A to 7C are merely examples.

  When the objective lens 104 is selected, as schematically shown in FIG. 7A, the magnetic piece 110b and the magnet 103b face each other, and the magnetic piece 110d and the magnet 103c face each other. Therefore, the lens holder 106 is held at the position shown in FIG. 1 by the magnetic attractive force (magnetic spring force) acting between the magnetic piece 110b and the magnet 103b and between the magnetic piece 110d and the magnet 103c.

  As shown in FIG. 7A, the portion of the focusing coil 107 where the current flows in the X direction is opposed to the magnets 103b and 103c. Further, as shown in FIG. 7B, the portions of the tracking coils 108a and 108b through which current flows in the Z direction are opposed to the magnets 103b and 103c, respectively. Further, as shown in FIG. 7C, portions of the tilt coils 109a and 109b through which current flows in the X direction are opposed to the magnets 103b and 103c.

  In this state, a deviation in the focal direction of a light spot formed on an optical disc (not shown) is detected by a focusing sensor using a known astigmatism method, and a current corresponding to the amount of the focusing deviation is focused. Flow through the coil 107. As shown in FIG. 7A, a driving force in the Z direction is generated by the magnetic action of the current flowing through the focusing coil 107 and the magnetic fields of the magnets 103b and 103c. With this driving force, the lens holder 106 is displaced in the Z direction (the optical axis direction of the objective lens 104), whereby the objective lens 104 is displaced in the Z direction, and focusing control is performed.

  Also, a deviation in the tracking direction of the light spot with respect to a desired track of the optical disc is detected by a known tracking sensor such as a differential push-pull method, and a current corresponding to the tracking deviation amount is supplied to the tracking coils 108a and 108b. . As shown in FIG. 7B, a driving force that urges the tracking coils 108a and 108b in the same direction in the X direction is generated by the action of the current flowing through the tracking coils 108a and 108b and the magnetic field of the magnets 103b and 103c. To do. With this driving force, the lens holder 106 is displaced in the X direction, whereby the objective lens 104 is displaced in the X direction (tracking direction), and tracking control is performed.

  Further, the relative tilt between the optical disk and the objective lens 104 is detected, and a current corresponding to the tilt is supplied to the tilt coils 109a and 109b. As shown in FIG. 7C, a driving force that biases the tilt coils 109a and 109b in opposite directions in the Z direction by the electromagnetic action of the current flowing through the tilt coils 109a and 109b and the magnetic field of the magnets 103b and 103c. Will occur. By this driving force, the inclination of the lens holder 106 (inclination about the axis in the Y direction) changes, and tilt control is performed.

  When switching from the objective lens 104 to the objective lens 105, a larger current is passed through the trackings 108a and 108b than during normal tracking control. By the action of the current flowing through the tracking coils 108a and 108b and the magnetic field of the magnets 103b and 103c, the above-described magnetic spring force is overcome, and the lens holder 106 moves from the state shown in FIG. 1 to the state shown in FIG. To do.

  As a result, the objective lens 105 is positioned at the center of the base 101 in the X direction (above the through-hole 101e), and information can be recorded and / or reproduced by the objective lens 105. In this state, since the magnetic piece 110a and the magnet 103a face each other, and the magnetic piece 110c and the magnet 103c face each other, the magnetic piece 110a acts between the magnetic piece 110a and the magnet 103b, and between the magnetic piece 110c and the magnet 103c. The lens holder 106 is held at the position shown in FIG. 3 by the magnetic attractive force (magnetic spring force).

  Further, in the state shown in FIG. 3, the portion of the focusing coil 107 where the current flows in the X direction faces the magnets 103a and 103c, and the portion of the tracking coils 108a and 108b where the current flows in the Z direction is the magnet 103a and 103c, respectively. 103c. Further, portions of the tilt coils 109a and 109b where current flows in the X direction are opposed to the magnets 103a and 103c. Therefore, focusing control, tracking control, and tilt control can be performed as in the state in which the objective lens 104 is selected.

  In the operation of the optical element driving apparatus described above, the position of the center of gravity of the movable part including the lens holder 106 is substantially intermediate between the objective lenses 104 and 105 in the horizontal plane (in the XY plane), and in the vertical direction (Z direction). Nearly the center position of the lens holder 106. As shown in FIG. 1, in the state where the objective lens 104 is selected, the resultant force of the driving force generated between the energized focusing coil 107 and the magnets 103b and 103c facing the focusing coil 107 is almost applied to the position of the center of gravity. It is configured as follows. Further, even when the objective lens 105 is selected as shown in FIG. 3, the resultant force of the driving force generated between the energized focusing coil 107 and the magnets 103a and 103c opposed thereto is applied to the position of the center of gravity. It is configured to be.

  The same applies to tracking control. That is, when the objective lens 104 is selected as shown in FIG. 1, the resultant force of the driving force generated between the tracking coil 108a and the magnet 103b and between the tracking coil 108b and the magnet 103c is substantially equal to the center of gravity. It is comprised so that it may be applied to a position. As shown in FIG. 3, even when the objective lens 105 is selected, the resultant force of the driving force generated between the tracking coil 108a and the magnet 103a and between the tracking coil 108b and the magnet 103c is almost at the position of the center of gravity. It is comprised so that it may be applied.

  In the operation of the optical element driving device described above, the restoring force of the lens holder 106 is obtained by the resultant force of the bending elastic force of the wires 111a to 111f and the magnetic attractive force (magnetic spring force) described above.

  As described above, according to the present embodiment, the lens holder 106 is moved in the X direction by using the tracking drive means (tracking coils 108a and 108b and magnets 103a to 103c), whereby the objective lenses 104 and 105 are moved. Since the switching is performed, it is not necessary to move a heavy component, and the objective lenses 104 and 105 can be switched with a simple configuration. Further, since it is not necessary to provide a dedicated mechanism for switching the objective lenses 104 and 105, the component cost can be reduced and the number of assembling steps can be reduced.

  Further, by utilizing the magnetic attractive force of the magnetic pieces 110a to 110d and the magnets 103a to 103c, the objective lens 104 is stably held at the position shown in FIG. 1, and the objective lens 105 is placed at the position shown in FIG. Can be held stably.

  Further, since the common magnets 103a to 103c are used for tracking control and focusing control, the number of parts can be reduced and the cost of the optical element driving device can be reduced.

  Further, it becomes possible to apply a driving force to the position of the center of gravity of the movable part made up of the holder 106 and each component mounted thereon, and as a result, focusing control and tracking control can be stably performed.

  Magnets 103a to 103c are arranged on both sides of the holder 106 in the Y direction. When the objective lens 104 is selected, the magnet 103b faces each coil. When the objective lens 105 is selected, the magnet 103a faces each coil. In either case, since the magnet 103c faces each coil, the volume of the magnet can be reduced. As a result, the optical element driving device can be reduced in size and the cost can be reduced.

  Further, by providing the tilt coils 109a and 109b, it is possible to perform attitude control, that is, tilt control, in which the optical axis of the objective lens and the recording surface of the optical disk are orthogonal.

  Further, since the holder 106 is supported using the wires 111a to 111f, the holder 106 can be supported to be movable in the focusing direction and the tracking direction, and can be supported to be movable in the tilt direction. . Furthermore, since the wires 111a to 111f also serve as current supply means to each coil, the number of parts can be reduced and the cost can be reduced.

Embodiment 2. FIG.
FIG. 8A is a perspective view showing an optical element driving apparatus according to Embodiment 2 of the present invention, and shows a state in which one of the two optical elements is selected. FIG. 8B is a perspective view illustrating a configuration example of a magnet of the optical element driving device illustrated in FIG. 9A, 9B, and 9C are a front view, a side view, and a plan view, respectively, showing the optical element driving device shown in FIG. FIG. 10 is a perspective view showing a state where the optical element driving apparatus shown in FIG. 8 has selected the other optical element. 11A, 11B, and 11C are a front view, a side view, and a plan view corresponding to FIG. 10, respectively. FIG. 12 is a perspective view showing the optical element driving apparatus shown in FIG. 8 divided into a movable part and a fixed part. FIG. 13 is an exploded perspective view showing a movable part of the optical element driving apparatus shown in FIG. 8 to 13, the same reference numerals are given to the same components as those of the first embodiment.

  As shown in FIG. 8A, in the second embodiment, two magnets 123a and 123b that are long in the X direction are arranged on both sides of the lens holder 126 in the Y direction. The magnets 123a and 123b have a length that covers the movement range of the lens holder 126 in the X direction (for example, about 1.5 times the length of the lens holder 126 in the X direction). The magnets 123a and 123b have magnetic pole faces parallel to the XZ planes facing each other. Each of the magnets 123a and 123b has a structure divided into a total of six regions (magnetic pole faces), three in the X direction and two in the Y direction, so that adjacent magnetic pole faces do not have the same polarity. Multipolar magnetized.

  As shown in FIG. 8B, the magnet 123a is divided into, for example, three magnetic pole surfaces 301, 302, and 303 divided in the X direction on the upper stage (+ Z side) and in the X direction on the lower stage (−Z side). Three magnetic pole surfaces 304, 305, and 306. For example, the magnetic pole surfaces 301, 302, and 303 of the magnet 123a are magnetized in order of N pole, S pole, and N pole, respectively, and the magnetic pole surfaces 304, 305, and 306 are sequentially changed to S pole, N pole, and S pole. Each is magnetized. The other magnet 123b has a similarly divided structure. Note that the magnetic poles (N pole and S pole) of the magnets 123a and 123b shown in FIG. 8B are merely examples.

  As shown in FIG. 8A, the base 121 has fixed walls 121a and 121b erected so that the magnets 123a and 123b can be fixed. In the fixed walls 121a and 121b, the portion between the portion where the magnets 123a and 123b are fixed and the base 121 is configured to have a narrow dimension in the X direction.

  As shown in FIG. 9, the lens holder 126 has a substantially rectangular parallelepiped shape, and two wires 131a, 131b, 131c, and 131d are attached to both ends in the X direction. The wires 131a and 131b are provided side by side in the Z direction, and the respective distal ends thereof are fixed to a protrusion 126a formed on one end surface of the lens holder 126 in the X direction. The end portions of the wires 131 a and 131 b are fixed to a substrate 132 attached to the support base 102. Similarly, the wires 131c and 131d are provided side by side in the Z direction, and the respective front ends thereof are fixed to a protrusion 126b formed on the other end surface of the lens holder 126 in the X direction. The end portions of the wires 131c and 131d are fixed to a substrate 132 attached to the support base 102. The lens holder 126 is supported by the support base 102 by these wires 131a to 131d.

  Due to the elastic deformation of the wires 131a to 131d, the lens holder 126 is movable in the substantially X direction between the position shown in FIG. 8 and the position shown in FIG. When the lens holder 126 is in the position shown in FIG. 8, information can be recorded on and reproduced from the optical disk by the objective lens 104, or both. When the lens holder 126 is at the position shown in FIG. 10, information can be recorded on and reproduced from the optical disk by the objective lens 105, or both.

  As shown in FIG. 13, two focusing coils 127 a, 127 b, 127 c, and 127 d are provided on each of two side surfaces parallel to the XZ plane of the lens holder 126. Among the focusing coils 127 a to 127 d, the focusing coils 127 a and 127 b are fixed so as to be aligned in the X direction on one side surface parallel to the XZ plane of the lens holder 126 (the surface away from the support base 102). Similarly, the focusing coils 127c and 127d are fixed so as to be aligned in the X direction on the other side surface (the surface on the support base 102 side) parallel to the XZ surface of the lens holder 126. Each of the focusing coils 127a to 127d has a winding axis in the Y direction, and is wound in a substantially rectangular shape so that current flows in the X direction and the Z direction.

  Two tracking coils 128a, 128b, 128c, and 128d are provided on each of two side surfaces of the lens holder 126 parallel to the XZ plane. Of the tracking coils 128a to 128d, the tracking coils 128a and 128b are fixed so as to be positioned approximately between the focusing coils 127a and 127b and aligned in the Y direction. Similarly, the tracking coils 128c and 128d are fixed so as to be positioned approximately between the focusing coils 127c and 127d and aligned in the Y direction. Each of the tracking coils 128a to 128d has a winding axis in the Y direction, and is wound in a substantially rectangular shape so that a current flows in the X direction and the Z direction.

  The optical element driving apparatus according to the present embodiment is configured to perform only focusing control and tracking control, and thus is not provided with a tilt coil.

  Two magnetic pieces 130 a, 130 b, 130 c, and 130 d are provided on each of two side surfaces parallel to the XZ plane of the lens holder 126. Among the magnetic pieces 130a to 130d, the magnetic pieces 130a and 130b are arranged inside the windings of the tracking coils 128a and 128b, respectively, and the magnetic pieces 130c and 130d are inside the windings of the tracking coils 128c and 128d, respectively. Is arranged.

  Next, the operation of the optical element driving device according to this embodiment will be described. First, the case where the objective lens 104 is selected as shown in FIG. 8 will be described. FIG. 14 is a schematic diagram showing the relationship between the magnet 123a and each coil. In a state where the objective lens 104 is selected, the magnetic pieces 130a and 130b attached to the lens holder 126 (not shown in FIG. 14) are the boundary portions of the magnetic pole surfaces 305 and 306 of the magnet 123a and the magnetic pole surfaces 302 and 303. It faces each boundary part. Similarly, the magnetic pieces 130c and 130d attached to the lens holder 126 are opposed to the boundary portions of the magnetic pole surfaces 305 and 306 and the boundary portions of the magnetic pole surfaces 302 and 303, respectively.

  The portion of the focusing coil 127a in which the current flows in the X direction is opposed to the magnetic pole surfaces 302 and 305 of the magnet 123a having opposite polarities, and the portion of the focusing coil 127b in which the current flows in the X direction is the opposite polarity of the magnet 123a. Are opposed to the magnetic pole surfaces 303 and 306. Similarly, the portion of the focusing coil 127c where the current flows in the X direction is opposed to the magnetic pole surfaces 303 and 306 of the magnet 123b having opposite polarities, and the portion of the focusing coil 127d where the current flows in the X direction is the portion of the magnet 123b. The magnetic pole faces 302 and 305 having opposite polarities are opposed to each other.

  Further, the two portions of the tracking coil 128a in which the current flows in the Z direction are opposed to the magnetic pole surfaces 305 and 306 of the magnet 123a having opposite polarities, and the two portions of the tracking coil 127b in which the current flows in the Z direction are The magnets 123a are opposed to the magnetic pole surfaces 302 and 303 having opposite polarities. Similarly, the two portions of the tracking coil 128c where the current flows in the Z direction are opposed to the magnetic pole surfaces 305 and 306 of the magnet 123b having opposite polarities, and the two portions of the tracking coil 128d where the current flows in the Z direction are The magnet 123b faces the magnetic pole surfaces 302 and 303 having opposite polarities.

  In this state, a deviation in the focal direction of a light spot formed on an optical disc (not shown) is detected by a focusing sensor using a known astigmatism method, and a current corresponding to the amount of the focusing deviation is focused. It flows through the coils 127a to 127d. A driving force in the Z direction is generated by the action of the current flowing through the focusing coils 127a and 127b and the magnetic field of the magnet 123a, and the action of the current flowing through the focusing coils 127c and 127d and the magnetic field of the magnet 123b. With this driving force, the lens holder 126 is displaced in the Z direction (the optical axis direction of the objective lens 104), whereby the objective lens 104 is displaced in the Z direction, and focusing control is performed.

  Further, a deviation in the tracking direction of the light spot with respect to a desired track of the optical disk is detected by a known tracking sensor such as a differential push-pull method, and a current corresponding to the tracking deviation amount is caused to flow through the tracking coils 128a to 128d. Due to the action of the current flowing through the tracking coils 128a and 128b and the magnetic field of the magnet 123a, and the action of the current flowing through the tracking coils 128c and 128d and the magnetic field of the magnet 123b, a driving force for displacing the lens holder 126 in the X direction is generated. . With this driving force, the lens holder 126 is displaced in the X direction, whereby the objective lens 104 is displaced in the X direction (tracking direction), and tracking control is performed.

  When switching from the objective lens 104 to the objective lens 105, a larger current is supplied to the tracking 128a to 128d than in the normal tracking operation. The lens holder 126 overcomes the above-described magnetic spring force by the action of the current flowing through the tracking coils 128a and 128b and the magnetic field of the magnets 123a and 123b and the action of the current flowing through the tracking coils 128c and 128d and the magnetic field of the magnet 123b. Moves in the X direction from the state shown in FIG. 8 to the state shown in FIG. Thereby, information can be recorded and / or reproduced by the objective lens 105.

  In this state, the magnetic pieces 130a and 130b attached to the lens holder 126 face the boundary portions of the magnetic pole surfaces 304 and 305 of the magnet 123a and the boundary portions of the magnetic pole surfaces 301 and 302, respectively. Similarly, the magnetic pieces 130c and 130d attached to the lens holder 126 face the boundary portions of the magnetic pole surfaces 304 and 305 and the boundary portions of the magnetic pole surfaces 301 and 302, respectively.

  Further, the two portions of the focusing coil 127a in which the current flows in the X direction are opposed to the magnetic pole surfaces 301 and 304 of the magnet 123a, and the two portions of the focusing coil 127b in which the current flows in the X direction are the magnetic pole surfaces 302 of the magnet 123a. , 305. Similarly, the portion of the focusing coil 127c where the current flows in the X direction faces the magnetic pole surfaces 302 and 305 of the magnet 123b, and the two portions of the focusing coil 127d where the current flows in the X direction are the magnetic pole surfaces 301 and 305 of the magnet 123b. It faces 304.

  Further, the portion of the tracking coil 128a in which the current flows in the Z direction faces the magnetic pole surfaces 304 and 305 of the magnet 123a, and the portion of the tracking coil 128b in which the current flows in the Z direction faces the magnetic pole surfaces 301 and 302 of the magnet 123a. To do. Similarly, the portion of the tracking coil 128c where the current flows in the Z direction faces the magnetic pole surfaces 304 and 305 of the magnet 123b, and the portion of the tracking coil 128d where the current flows in the Z direction is on the magnetic pole surfaces 301 and 302 of the magnet 123b. opposite.

  Therefore, focusing control, tracking control, and tilt control can be performed as in the state in which the objective lens 104 is selected.

  In the present embodiment, similarly to the first embodiment, it is not necessary to move a heavy component, and the objective lenses 104 and 105 can be switched with a simple configuration. Further, by combining the means for switching the objective lenses 104 and 105 and the tracking drive means, the parts cost can be reduced and the number of assembling steps can be reduced.

  In addition, in the present embodiment, since the magnets 123a and 123b are multipolar magnetized, the utilization efficiency of each coil can be increased.

  In the second embodiment, an example in which only focusing control and tracking control are performed has been described. However, tilt control can be further performed. In this case, two tilt coils having a portion in which the current flows in the X direction are arranged at the lower part of the inner surface of the lens holder 126 so as to face the permanent magnets 123a and 123b. In addition to the wires 131a to 131d, two more elastic bodies are provided between the lens holder 126 and the substrate 132, and are electrically connected to the respective tilt coils. Thereby, as described in the first embodiment, tilt control can be performed by changing the tilt of the lens holder 126 in the X direction.

  The optical element driving apparatus according to Embodiments 1 and 2 described above is configured to switch between the two objective lenses 104 and 105. However, the number of objective lenses to be switched is not limited to two, and may be three or more. Good. Further, an optical element other than the objective lens may be switched. Further, the recording medium is not limited to a Blu-ray disc or DVD, and other recording media may be used.

It is a perspective view which shows the state which the optical element drive device concerning Embodiment 1 of this invention selected one optical element. It is the front view (A), side view (B), and top view (C) which show the optical element drive device shown in FIG. It is a perspective view which shows the state which the optical element drive device shown in FIG. 1 selected the other optical element. It is the front view (A), side view (B), and top view (C) corresponding to FIG. FIG. 2 is a perspective view (A) showing the optical element driving device shown in FIG. 1 divided into a movable part and a fixed part, and a schematic view (B) showing a positional relationship between a magnet and a coil. It is a disassembled perspective view which shows the movable part of the optical element drive device shown in FIG. FIG. 6 is a schematic diagram for explaining the operation of the optical element driving device according to the first embodiment. It is the perspective view (A) which shows the state which the optical element drive device concerning Embodiment 2 of this invention selected one optical element, and the perspective view (B) which shows the structural example of a magnet. It is the front view (A), side view (B), and top view (C) which show the optical element drive device shown in FIG. It is a perspective view which shows the state which the optical element drive device shown in FIG. 8 selected the other optical element. It is the front view (A), side view (B), and top view (C) corresponding to FIG. FIG. 9 is a perspective view showing the optical element driving device shown in FIG. 8 divided into a movable part and a fixed part. It is a disassembled perspective view which shows the movable part of the optical element drive device shown in FIG. It is a perspective view which shows the positional relationship of the magnet and each coil of the optical element drive device shown in FIG.

Explanation of symbols

  101, 121 base, 102 support base, 103a, 103b, 103c, 123a, 123b permanent magnet, 104, 105 objective lens, 106, 126 lens holder, 107, 127a, 127b, 127c, 127d focusing coils, 108a, 108b, 128a, 128b tracking coil, 109a, 109b tilt coil, 110a, 110b, 110c, 110d magnetic piece, 111a, 111b, 111c, 111d, 111e, 111f wire, 112, 132 substrate.

Claims (7)

A holder for holding two switchable optical elements for condensing light on a recording medium;
Elastically deformable support means for supporting the holder;
Focusing driving means for driving the holder in the optical axis direction of the optical element;
Tracking drive means for driving the holder in a tracking direction substantially orthogonal to the optical axis direction;
An optical element driving apparatus for switching the optical element for condensing light on the recording medium by moving the holder by the tracking driving means ,
The tracking drive means includes
A coil fixed to the holder;
First and second magnets arranged side by side in the tracking direction so as to face each of the coils when one of the two optical elements is selected,
A third magnet disposed on the opposite side of the first and second magnets so as to face the coil even when any optical element is selected;
With
The optical element is held at a position for condensing light on the recording medium by a magnetic interaction between a magnetic body provided in the holder and the first, second, or third magnet. Optical element driving device. 2. The optical element driving apparatus according to claim 1 , wherein the tracking driving unit and the focusing driving unit share the first, second, and third magnets. Said first and second magnets, said a third magnet, according to claim 1, characterized in that arranged on both sides of the holder in a direction substantially perpendicular to the optical axis direction and the tracking direction, or 3. The optical element driving device according to 2. Driving force of the focusing drive means, and the driving force of the tracking drive means, according to claim 1, characterized in that acting on the center-of-gravity position of the movable part including the holder and the optical element to 3 Optical element driving apparatus. It said support means includes optical element driving device according to any one of claims 1 to 4, characterized in that a plurality of wires coupled to the holder. 6. The optical element driving apparatus according to claim 5 , wherein the plurality of wires also serve as current supply means to each coil that is a component of the focusing coil driving means and the tracking coil driving means. The apparatus further comprises tilt drive means for changing the tilt of the optical element with respect to the recording medium by rotating the holder about an axis substantially orthogonal to the optical axis direction and the tracking direction. optical element driving device according to any one of claims 1 to 6.

Images