JP2006164519A - Optical means driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical means driving device which can easily be driven in the tracking direction. <P>SOLUTION: The optical means driving device has an optical means for condensing laser light in a disk-like recording medium; a holder which holds the optical means; a fixing member which is arranged at a predetermined interval of the holder; a focusing coil, a tracking coil, and a tilt coil for driving the optical means; and a pair of support means constituted of at least three linear elastic objects which supports the holder movable in three directions, a part of the tracking coil coming to the outside of a rectangular formed by an end part of a pair of linear elastic members closest to the disk-like recording medium on the holder side and an end part of a pair of linear elastic objects farthest from the disk-like recording medium on the holder side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information recording / reproducing apparatus for recording or reproducing information by forming a beam spot on a recording surface of a disc-shaped recording medium, and more particularly to an optical means driving apparatus for forming the beam spot at an accurate position. Is.

  An optical means driving apparatus for driving a condensing lens for forming a beam spot on a disc-shaped recording medium such as a DVD (Digital Versatile Disc) or a CD (Compact Disc) has a converging lens in a direction perpendicular to the disc surface ( Control is performed so that the beam spot is accurately formed on the pit row by driving in the focusing direction) and in the radial direction of the disk (tracking direction). Further, when the optical axis tilt (hereinafter referred to as tilt) of the condensing lens with respect to the disc surface occurs due to surface deflection or disc deflection due to disc rotation, the optical means driving device mounts the condensing lens around the tangential direction of the disc. Rotating tilt control is performed.

  An example of the optical means driving device that drives the condenser lens in the focusing direction, the tracking direction, and the tilt direction as described above is described in Patent Document 1 shown below. FIG. 10 shows a perspective view of the optical means driving apparatus described in Patent Document 1. In FIG. The objective lens 101 is fixed to the lens holder 102. In addition, six strip-shaped metal plate springs 103a to 103c and 103d to 103f are provided on the side surface of the lens holder 102, and printed coils 104a and 104b are fixed to other side surfaces. On the other hand, the base 105 includes a suspension holder 106 for supporting the lens holder 102 and permanent magnets 107 a to 107 d for controlling the lens holder 102. The lens holder 102 is supported by the base 105 by connecting the strip-shaped metal plate springs 103a to 103c and 103d to 103f and the suspension holder 106 with suspension wires (linear elastic bodies) 108a to 108c and 108d to 108f. ing. At this time, the printed coil 104a is disposed between the permanent magnet 107a and the permanent magnet 107b, and the printed coil 104b is disposed between the permanent magnet 107c and the permanent magnet 107d.

  The lens holder 102 is moved in the optical axis direction Fo (hereinafter also referred to as the focusing direction) by supplying current so that electromagnetic force in the same direction is generated in the focusing coils (not shown) built in the print coils 104a and 104b. Be controlled. Further, by supplying current so that electromagnetic force in the same direction is generated in tracking coils (not shown) built in the print coils 104a and 104b, the lens holder 102 is in the tracking direction which is the radial direction of the optical recording medium. Controlled by Tk. Further, by supplying a current so that an electromagnetic force in the reverse direction is generated in the focusing coil (not shown), the lens holder 102 receives a rotational moment about the tracking direction Tk and is controlled in the tilt direction Ti. FIG. 11 is a cross-sectional view showing how the lens holder is controlled in the tilt direction Ti. When an electromagnetic force in the opposite direction is generated in the focusing coil (not shown), the twist angle and the amount of deflection of the strip-shaped metal plate spring 103a and the strip-shaped metal plate 103c are the same in size and reverse in direction. As a result, the center of the strip-shaped metal plate spring 103b becomes the rotation center O in the tilt direction Ti, and the lens holder 102 is rotated by θ and driven in the tilt direction. By the above control, driving in three directions of the focusing direction Fo, the tracking direction Tk, and the tilt direction Ti can be performed.

JP 2001-297460 A

  In the optical means driving apparatus shown in FIG. 10, since the six strip-shaped metal plate springs 103a to 103f are used as the contacts on the lens holder 102 side of the suspension wires 108a to 108f, the parts cost is increased and the assembly is performed. There was a problem that man-hours increased. In addition, since the six strip-shaped metal plate springs 6a to 6f are used as the support mechanism of the lens holder 102, there is a problem that variations occur in products, and accordingly, tilt operations vary.

  The present invention has been made in view of the above problems, and provides an optical means driving device that can stably perform three-way driving in a focusing direction Fo, a tracking direction Tk, and a tilt direction Ti and can be easily manufactured. The purpose is to do.

The optical means driving device according to the present invention is
Optical means for condensing laser light on a disk-shaped recording medium;
A holder for holding the optical means;
A fixing member disposed at a predetermined interval from the holder;
A focusing coil for driving the optical means in the optical axis direction of the laser light, a tracking coil for driving the optical means in the radial direction of the disc-shaped recording medium,
A tilt coil for rotating the optical means around the central axis about an axis orthogonal to the optical axis direction;
A pair of support means composed of at least three linear elastic bodies for supporting the holder so as to be movable around the optical axis direction, the radial direction, and the central axis;
Each of the linear elastic bodies has one end fixed to the holder and the other end fixed to a fixing member,
Each of the linear elastic bodies forming a pair is disposed at a position that is substantially the same in the optical axis direction,
A part of the tracking coil is located on the holder side end of the pair of linear elastic bodies closest to the disk-shaped recording medium and on the holder side of the pair of linear elastic bodies farthest from the disk-shaped recording medium. It is supposed to be outside the quadrangle formed by the end portions.

  Since the optical means driving apparatus according to claim 1 of the present invention is configured as described above, the force in the tracking direction can be efficiently transmitted to the holder.

FIG. 1 is a perspective view of an optical means driving apparatus according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing configurations of a fixed portion 15 and a movable portion 14 of the optical means driving apparatus shown in FIG. FIG. 3 is a view showing (a) the upper surface portion and (b) the side surface portion of the optical means driving apparatus shown in FIGS. 1 and 2.
As shown in FIG. 2, the fixed portion 15 includes a yoke 7, permanent magnets 6 a and 6 b, and a circuit board 8. The permanent magnets 6 a and 6 b are magnetized to a single pole and are fixed to the yoke 7. The yoke 7 is formed with convex portions 7a and 7b and a through hole 7h through which laser light passes.

  On the other hand, the movable portion 14 includes a condenser lens 1, a holder 2, a focusing control coil 3, tracking control coils 4a, 4b, 4c, 4d, and tilt control coils 5a, 5b. The condensing lens 1 is fixed to the upper part of the holder 2, and condenses the laser beam that has passed through the through hole 7h onto a disk-shaped recording medium. The holder 2 is integrally provided with a focusing control coil 3, tracking control coils 4a to 4d, and tilt control coils 5a and 5b. The focusing control coil 3 is wound around the holder 2, and the tilt control coils 5 a and 5 b are held by a pair of rectangular column parts 20 a and 20 b provided at the lower part of the holder 2. The focusing control coil 3 and the tilt control coils 5 a and 5 b are arranged such that the central axis of each coil is in the same direction as the optical axis of the condenser lens 1. On the other hand, the tracking control coils 4 a and 4 b are arranged on the side surface of the holder 2. As shown in FIG. 2, positioning members 12 a and 12 b for arranging the tracking control coils 4 a and 4 b at appropriate positions are provided on the side surface of the holder 2. Similarly, the tracking control coils 4c and 4d are positioned on the opposite side surface of the holder 2 by positioning members 12c and 12d (not shown). The holder 2 is provided with insertion holes 2a and 2b through which convex portions 7a and 7b formed in the yoke 7 are inserted.

  On the other side surface of the holder 2, a pair of supports 2c and 2d are provided. Each support 2c, 2d is provided with stators 29a-29c, 29d-29f to which one ends of linear elastic bodies 9a-9c and 9d-9f having conductivity are connected. The linear elastic bodies 9a to 9f are fixed to the supports 2c and 2d by the stators 29a to 29f and are electrically connected to the start and end of each of the three control coils. The other ends of the linear elastic bodies 9 a to 9 f are electrically connected to the circuit board 8 via a stator (not shown) provided in a circular arc shape on the side surface of the yoke 7. Thus, the linear elastic bodies 9a to 9f support the movable portion 14 so as to be movable in the three control directions of the focusing direction Fo, the tracking direction Tk, and the tilt direction Ti, and supply a control current to the control coils.

  As shown in FIG. 4, the stators 29a to 29c and 29d to 29f (and the corresponding stators of the yoke 7) of the supports 2c and 2d are arranged on an arc indicated by a broken line. That is, the linear elastic bodies 9 a to 9 c and 9 d to 9 f are arranged on cylindrical surfaces having different centers and support the holder 2. Here, each cylindrical surface may have the same center.

  The operation of the optical means driving apparatus shown in FIGS. The condensing lens 1 detects the focusing deviation of the condensing spot formed on the disk-shaped recording medium and the track deviation of the condensing spot with respect to a desired track by a known method such as an astigmatism method or a phase difference method. At that time, by supplying a signal corresponding to the amount of focusing deviation and the amount of tracking deviation to the focusing coil 3 and the tracking coils 4a and 4b, each of them is interacted with the magnetic field formed by the permanent magnets 6a and 6b. Forces in the focusing direction Fo and the tracking direction Tk are generated in the coil. Thus, focusing control and tracking control for moving the condenser lens according to the amount of focusing deviation and the amount of tracking deviation are performed.

  At the same time, when the tilt of the optical axis with respect to the disk surface of the laser beam occurs due to surface deflection caused by bending or rotation of the disk-shaped recording medium, this tilt amount is detected by a known method, and a signal corresponding to the tilt deviation amount is generated. This is supplied to the tilt control coils 5a and 5b. At this time, by supplying a current that drives the tilt control coil 5a in the + Fo direction (or -Fo direction) and the tilt control coil 5b in the opposite -Fo direction (+ Fo direction), the holder 2 moves in the focusing direction Fo. The axis is rotated in the tilt direction indicated by Ti in the drawing with the axis orthogonal to the tracking direction Tk (axis parallel to the longitudinal direction of the linear elastic bodies 9a to 9f) as the center. At this time, since the linear elastic bodies 9a to 9c and 9d to 9f are arranged on the cylindrical surface, they are twisted in the tilt direction Ti while maintaining substantially the same length. Thereby, when the holder 2 is rotated in the tilt direction Ti, it is possible to reduce the bending force in the longitudinal direction generated in the linear elastic bodies 9b and 9e arranged at the center. That is, the holder 2 can be stably tilted in the tilt direction Ti. That is, since the deformation of the linear elastic bodies 9a to 9f at the time of tilt control can be limited to only bending deformation, three-direction control including focusing control, tracking control, and tilt operation can be performed stably.

  As can be seen from FIG. 3B and FIG. 4, in the optical means driving apparatus according to the present embodiment, the widths of the tracking control coils 4a to 4d in the height direction are set to the linear elastic bodies 9a and 9c, 9d and 9f. The distance is smaller than the interval, and the side of each control coil located outside the holder 2 is projected outward. This is the portion indicated by A in FIG. 4 where the force in the tracking direction Tk acts on the tracking control coils 4a and 4b. In order to perform tracking control efficiently, A of the tracking control coils 4a and 4b. This is because it is desirable to keep the portion A ′ where the force acting in the direction opposite to the force acting on the portion indicated by (3) acts away from the permanent magnets 6a and 6b. That is, the force in the tracking direction can be efficiently transmitted to the holder 2 by expanding the width of the tracking control coils 4a and 4b relative to the width of the permanent magnets 6a and 6b.

  In the present embodiment, as shown in FIG. 4, the central linear elastic bodies 9b, 9e are arranged outside the other linear elastic bodies 9a, 9c, 9d, 9e, and the tracking control coils 4a, 4b. The width of the tracking control coils 4a and 4b is increased with respect to the permanent magnets 6a and 6b by making the width in the height direction smaller than the interval between the linear elastic bodies 9a and 9c, 9d and 9f. Thereby, during tracking control, the reaction force acting on the portion A ′ can be reduced, and the driving force in the tracking direction can be efficiently transmitted to the holder 2.

  FIG. 5 is a view showing a modification of the optical means driving apparatus according to the present embodiment. FIG. 6 is a view showing (a) the upper surface portion and (b) the side surface portion of the optical means driving apparatus shown in FIG. The optical means driving apparatus shown in FIGS. 5 and 6 drives the holder 2 by a single permanent magnet 6 provided on the yoke 7.

  When the holder 2 is driven using the single permanent magnet 6 in this way, the driving points (power points) for focusing control, tracking control, and tilt control and the condensing lens 1 as the action point can be matched. Can not. The driving points for focusing control, tracking control, and tilt control are the facing portions of the focusing control coil 3, the tracking control coils 4a and 4b, and the tilt control coils 5a and 5b facing the permanent magnet 6. When performing each control, if the distance between the drive point and the action point is increased, the driving force is indirectly transmitted to the action point, and the control becomes unstable. Such a problem can be solved by adjusting the position of the fulcrum, that is, the positions of the supports 2c and 2d. That is, the supports 2c and 2d may be provided at appropriate positions between the focusing control, tracking control, and tilt control drive points and the condensing lens 1 as the action point. Further, a counterweight may be provided so that the center of gravity of the holder 2 is in an appropriate position so that unnecessary vibration does not occur in the holder 2. By using the single permanent magnet 6 in this way, the cost can be suppressed.

  FIG. 7 is a diagram illustrating another configuration of the movable portion 14. In the movable part 14 shown in FIG. 7, the tracking coil 4c is composed of a single coil. Thus, the cost can be suppressed by using one tracking coil.

  FIG. 8 is a perspective view showing another modification of the optical means driving apparatus. The permanent magnet 6c of the optical means driving apparatus shown in FIG. 8 is configured wider than the permanent magnets 6a and 6 of the optical means driving apparatus shown in FIGS. Correspondingly, as shown in FIG. 9, the portions indicated by A ′ of the tracking control coils 4f and 4g are arranged outside the linear elastic bodies 9b and 9e in order to secure a distance from the permanent magnet 6a. Yes. By increasing the width of the permanent magnet 6c in this way, the amount of magnetic flux acting on the focusing coil 3 and the tilt coils 5a and 5b is increased, so that sufficient driving force for focusing control and tilt control is ensured. Can do. For tracking coils 4f and 4g, the driving force in the tracking direction Tk is efficiently transmitted to the holder by arranging the portion A 'where the reaction force acts during tracking control outside the linear elastic bodies 9b and 9e. Stable tracking control can be performed.

According to the optical means driving apparatus according to the present invention described above, the linear elastic bodies 9a to 9c and 9d to 9f that support the holder 2 are connected to the supports 2c and 2d in a substantially arc shape, respectively. It is possible to reduce the bending force generated in the longitudinal direction of the linear elastic bodies 9b, 9e disposed in the, and to perform stable tilt control.
Further, by arranging the linear elastic bodies 9a to 9c and 9d to 9f in an arc shape, the widths of the tracking coils 4a to 6d are expanded with respect to the permanent magnets 6a and 6b, and a force opposite to the tracking direction is generated. Thus, stable tracking control can be performed.
Moreover, as shown in FIGS. 5-8, manufacturing cost can be held down by using one permanent magnet and one tracking coil.

It is a perspective view which shows one Embodiment of the optical means drive device based on this invention. It is a disassembled perspective view of the optical means drive device concerning this invention. It is a figure which shows the upper surface part and side part of the optical means drive device based on this invention. It is a side view of the movable part of the optical means drive device concerning this invention. It is a perspective view which shows one Embodiment of the optical means drive device based on this invention. It is a figure which shows the upper surface part and side part of the optical means drive device based on this invention. It is a perspective view of the optical means drive device concerning this invention. It is a perspective view which shows one Embodiment of the optical means drive device based on this invention. It is a side view of the movable part of the optical means drive device concerning this invention. It is a perspective view which shows an example of an optical means drive device. It is a figure which shows operation | movement of an optical means drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical means, 2 Holder, 2a, 2b Insertion hole, 2c, 2d Support body, 29a, 29b, 29c, 29d, 29e, 29f Stator, 12a, 12b Positioning member, 20a, 20b Rectangular column member, 3 Focusing control coil 4a, 4b, 4c, 4d, 4f, 4g Tracking control coil, 5a, 5b Tilt control coil, 6, 6a, 6c Permanent magnet, 7 Yoke, 7a, 7b Convex part, 8 Circuit board, 9a, 9b, 9c, 9d, 9e, 9f Linear elastic body, 14 movable part, 15 fixed part.

Claims (5)

Optical means for condensing laser light on a disk-shaped recording medium;
A holder for holding the optical means;
A fixing member disposed at a predetermined interval from the holder;
A focusing coil for driving the optical means in the optical axis direction of the laser light, a tracking coil for driving the optical means in the radial direction of the disc-shaped recording medium,
A tilt coil for rotating the optical means around the central axis about an axis orthogonal to the optical axis direction;
A pair of support means composed of at least three linear elastic bodies for supporting the holder so as to be movable around the optical axis direction, the radial direction, and the central axis;
Each linear elastic body has one end fixed to the holder and the other end fixed to a fixing member,
Each of the linear elastic bodies forming a pair is disposed at a position that is substantially the same in the optical axis direction,
A part of the tracking coil is located on the holder side end of the pair of linear elastic bodies closest to the disk-shaped recording medium and on the holder side of the pair of linear elastic bodies farthest from the disk-shaped recording medium. An optical means driving device characterized in that it is outside a quadrangle formed by an end portion. The holder includes a pair of supports disposed on each of two opposing side surface portions,
The optical means driving apparatus according to claim 1, wherein one end of the linear elastic body is connected to each of at least three stators arranged in a substantially arc shape on each of the supports. 3. The optical means driving apparatus according to claim 1, wherein the linear elastic bodies have the same length. The tracking coil is disposed on a side surface of the holder perpendicular to the central axis, and one side of the tracking coil is disposed outside a magnet provided to face the tracking coil. The optical means driving device according to any one of claims 1 to 3. The single permanent magnet for driving the holder is provided, and the tracking coil is arranged on one side of the holder facing the permanent magnet. Optical means driving device.

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