JP2005310237A - Objective lens drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve reduction of unnecessary resonance at the time of driving to a focusing direction and driving to a tracking direction in an objective lens drive unit. <P>SOLUTION: The strength of a base section 6 to which a 1st multipole magnet 4 and a 2nd multipole magnet 5 are attached is weakened by change of a structure, and unnecessary resonance generated at the time of driving to the focusing direction F and driving to a tracking direction T of a lens folder 2 can be absorbed in the base section 6, and consequently, unnecessary resonance can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is an objective lens driving device for an optical head mounted on an optical disk device that optically records or reproduces information on a disk-shaped recording medium, and does not cause unnecessary resonance when driven in the focusing direction and the tracking direction. The present invention relates to an objective lens driving device.

  The objective lens driving device is incorporated in a device for optically recording or reproducing information on a disc-shaped recording medium such as a compact disc (hereinafter referred to as a disc) so as to be movable in a predetermined radial direction of the disc in parallel with the disc. In order to correct focusing deviation due to disc surface deflection and tracking deviation due to decentration, the objective lens is in a direction perpendicular to the disc that is the optical axis direction of the objective lens (hereinafter referred to as focusing direction), and the disc Driving is performed in two directions of the predetermined radial direction (hereinafter referred to as tracking direction).

  In recent years, optical disk devices have increased in density and transfer rate. Therefore, the need for high-precision positioning control of the objective lens and high-speed rotation of the optical disk to record and reproduce information has increased. ing. In an optical information recording / reproducing apparatus including such an objective lens driving device, if unnecessary resonance occurs in the objective lens driving device, the unnecessary resonance increases when docked with the optical base to form an optical head. Causes oscillation.

  In addition, downsizing of the apparatus, particularly reduction in thickness, is also required at the same time, and it is more difficult to construct an objective lens driving apparatus that does not cause unnecessary resonance in a limited space.

  Hereinafter, an example of a conventional objective lens driving device in the above-described thin configuration will be described with reference to the drawings.

  FIG. 5 is an exploded perspective view showing the configuration of the conventional objective lens driving device, FIG. 6 is a plan view showing the configuration of the conventional objective lens driving device, and FIG. 7B is a first diagram of the conventional objective lens driving device. FIG. 7A is a schematic plan view for explaining the positional relationship among the pole magnet 4, the second multipole magnet 5 and the printed coil 3, and FIG. 7A is a view of FIG. 7C is a schematic side view transparently showing the positional relationship between the second multipole magnet 5 and the tracking coil portions 3b and 3c, and FIG. 7C is a view of FIG. It is the typical side view which expressed perspectively the positional relationship of the 1st multipole magnet 4 and focusing coil part 3a in the case. FIG. 8 is a schematic diagram showing a result of simulation when a conventional objective lens driving device is driven.

  5, 6, 3 (a), 7 (b), and 7 (c), F is the focusing direction, T is the tracking direction, K is the focusing direction F and the direction K perpendicular to the tracking direction T. The focusing direction F, the tracking direction T, and the direction K have directions corresponding to the directions of the coordinate axes in the three-dimensional orthogonal coordinates.

  5 and 6, reference numeral 2 denotes a lens holder made of molded resin. The objective lens 1 is mounted on the lens holder 2, and is approximately along the focusing direction F at a position avoiding the objective lens 1. A rectangular through hole is drilled. A printed coil 3 is attached to a substantially central portion of the lens holder 2 in parallel to a plane including the focusing direction F and the tracking direction T.

  The printed coil 3 has a coil structure in which a conductive material is spirally attached around an axis parallel to the direction K on the substrate to form a coil structure, and the layers constituting the focusing coil portion 3a and the tracking coil portions 3b and 3c are arranged. Consists of two types of layers. The focusing coil portion 3a is disposed on the side closer to the objective lens 1, the tracking coil portions 3b and 3c are disposed on the side far from the objective lens 1, and the tracking coil portions 3b and 3c are wired in series.

  Further, the relay terminal plate 9 is fixed to each of the two side surfaces perpendicular to the tracking direction T of the lens holder 2, and both end terminals of the focusing coil 3a formed on the printed coil 3 and both ends of the tracking coil portions 3b and 3c. The terminals are connected by soldering.

  Therefore, the objective lens 1, the lens holder 2, the print coil 3, and the relay terminal plate 9 constitute a movable body. The movable body has a symmetrical shape with respect to a plane that includes the optical axis of the objective lens 1 and is perpendicular to the tracking direction T, and the center of gravity of the movable body is on a line that intersects the surface of the printed coil 3 on the plane. It is set to be located.

  Reference numeral 4 denotes a first multipole magnet having a plurality of magnetic pole regions on the same surface, and is composed of two magnetic pole regions, a magnetic pole region 4a and a magnetic pole region 4b, separated by one magnetic field boundary line parallel to the tracking direction T. ing.

  Reference numeral 5 denotes a second multipole magnet having a plurality of magnetic pole regions on the same surface, which is formed by combining two magnetic field boundary lines substantially parallel to the focusing direction F and one magnetic field boundary line parallel to the tracking direction T. It is composed of two magnetic pole areas, a quadrangular magnetic pole area 5a and a concave magnetic pole area 5b separated by a magnetic field boundary.

  The first multi-pole magnet 4 and the second multi-pole magnet 5 are arranged at a position where the printed coil 3 is sandwiched with a gap and close to the objective lens 1, and the first multi-pole magnet 4 is arranged in the mounting portion 6 a. On the far side, the second multi-pole magnet 5 is disposed on the mounting portion 6 b and is fixed to the base 6.

  The opposing magnetic pole surfaces of the magnetic pole region 4a of the first multipolar magnet 4 and the magnetic pole region 5a of the second multipolar magnet 5 are the S pole and the N pole, respectively, and the different polarities face each other. ing. Similarly, the magnetic pole surfaces 4b of the first multipole magnet 4 and the magnetic pole regions 5b of the second multipole magnet 5 that are partially opposed to each other are N-pole and S-pole, respectively, so that the different poles face each other. Is arranged.

  In the focusing coil portion 3a, the effective coil region 3a1 that contributes to the focusing drive is opposed to the magnetic pole region 4a of the first multipole magnet 4, and the effective coil region 3a2 is opposed to the magnetic pole region 4b of the first multipole magnet 4. Yes.

  In the tracking coil portion 3b, the effective coil region 3b1 that contributes to tracking drive is opposite to the magnetic pole region 5a of the second multipole magnet 5, and the effective coil region 3b2 is opposite to the magnetic pole region 5b of the second multipole magnet 5. Similarly, in the tracking coil portion 3c, the effective coil region 3c1 that contributes to tracking driving is the magnetic pole region 5a of the second multipole magnet 5, and the effective coil region 3c2 is the magnetic pole region 5b of the second multipole magnet 5. And facing each other.

  And the width dimension M of the tracking direction T of the 1st multipole magnet 4, the width dimension N of the tracking direction T of the 2nd multipole magnet 5, and the tracking direction of the attachment part 6a of the 1st multipole magnet 4 The relationship of the width dimension L is L <M <N.

  A total of four wires 7a to 7d are connected by soldering to the two relay terminal plates 9 to which both terminals of the focusing coil portion 3a and both terminals of the tracking coil portions 3b and 3c are connected. 7 d is soldered to a fixed substrate 10 attached to a suspension holder 8 fixed to the base 6.

  The wires 7a to 7d are made of an elastic metal material such as beryllium copper or phosphor bronze, and wires or rods having a cross-sectional shape such as a circle, a substantially polygon, or an ellipse are used. Further, the support center of the wires 7a to 7d is set to substantially coincide with the center of gravity of the movable body.

  Next, the operation of the objective lens driving device configured as described above will be described with reference to FIGS. 7 (a), 7 (b), and 7 (c).

  First, the driving operation of the movable body in the focusing direction F will be described.

  In FIG. 7C, when a current is passed through the focusing coil portion 3a in the direction of the arrow shown in the figure, the magnetic pole region 4a facing the effective coil region 3a1 is the S pole, and the magnetic pole region 4b facing the effective coil region 3a2 is the N pole. Therefore, a driving force in the arrow direction Pf is generated in the effective coil regions 3a1 and 3a2 of the focusing coil portion 3a. That is, the lens holder 2 is driven in the focusing direction F by the driving force Pf generated in the focusing coil portion 3a.

  Next, the driving operation of the movable body in the tracking direction T will be described.

  In FIG. 3A, when a current is passed through the tracking coil portions 3b and 3c in the direction of the arrow shown in the drawing, the effective coil region 3b1 and the magnetic pole region 5a facing the effective coil region 3c1 are the N pole, the effective coil region 3b2, and the effective coil. Since the magnetic pole region 5b facing the region 3c2 is the S pole, a driving force in the arrow direction Pt is generated in each of the effective coil regions 3b1, 3b2, 3c1, and 3c2 of the tracking coil portions 3b and 3c. That is, the lens holder 2 is driven in the tracking direction T by the driving force Pt generated in the tracking coil portions 3b and 3c.

  As described above, when the objective lens driving device described above is driven in the focusing direction and the tracking direction, unnecessary resonance occurs in one zone of the base 6. This can be confirmed by simulation. As can be seen from the simulation results shown in FIG. 8, the place that looks whitish as a whole is a place that shows the occurrence of unnecessary resonance and spreads as a whole.

Although not the above description itself, Patent Document 1 or the like is known as an example of a conventional technique that considers unnecessary resonance.
JP 2002-279661 A

  However, the conventional example has the following problems when it is required to reduce unnecessary resonance.

  In the driving in the conventional example, the base 6 vibrates in a minute amount due to the repulsive force generated when driving in the forcing direction and the tracking direction, and unnecessary resonance occurs.

  The present invention has been made to solve such a problem, and can reduce unnecessary resonance, ensure good tracking performance even when the optical disk is rotated at high speed, and suppress deterioration of the recording / reproducing signal. An object of the present invention is to provide an objective lens driving device.

  An objective lens driving device according to the present invention includes an objective lens having an optical axis in a focusing direction that is a direction perpendicular to the disc, a movable body having a lens holder for holding the objective lens, a base, and the movable body with respect to the base. A support means that elastically supports the lens in a focusing direction and a tracking direction that is a radial direction of the disk, a focusing coil and a tracking coil that are attached to the approximate center of the lens holder, a first multipole magnet fixed to the base, and a first In the objective lens driving device having a configuration in which the objective lens is arranged at a position shifted from the center of the movable body, the focusing coil and the tracking coil are perpendicular to the focusing direction and the tracking direction. Flat with each winding axis in the direction The first multipole magnet and the second multipole magnet are arranged on the side closer to the objective lens so as to sandwich the focusing coil and the tracking coil with a gap along the winding axis direction. A multipolar magnet, a second multipolar magnet is arranged on the far side, and the strength of the base portion to which the first multipolar magnet and the second multipolar magnet are attached is weakened.

  According to the present invention, it is possible to disperse the vibration of the base generated when driving in the focusing direction and the tracking direction by reducing the strength of the base portion to which the first multipolar magnet and the second multipolar magnet are attached. Unnecessary resonance can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
1 is an exploded perspective view showing the configuration of an objective lens driving device according to Embodiment 1 of the present invention, FIG. 2 is a plan view showing the configuration of the objective lens driving device according to Embodiment 1 of the present invention, and FIG. These are the typical top views for demonstrating the positional relationship of the 1st multipole magnet 4, the 2nd multipole magnet 5, and the printed coil 3 of the objective lens drive device by Embodiment 1. FIG. ) Is a schematic side view transparently showing the positional relationship between the second multipolar magnet 5 and the tracking coil portions 3b and 3c when FIG. 3B is viewed from the direction of the arrow U, FIG. FIG. 3B is a schematic side view transparently showing the positional relationship between the first multipole magnet 4 and the focusing coil portion 3a when FIG. 3B is viewed from the direction of the arrow V. FIG. 4 is a schematic diagram showing the result of simulation when the objective lens driving device according to the present embodiment is driven.

  1, 2, 3 (a), 3 (b), and 3 (c), F is a focusing direction, T is a tracking direction, K is a focusing direction F and a direction K perpendicular to the tracking direction T. The focusing direction F, the tracking direction T, and the direction K have directions corresponding to the directions of the coordinate axes in the three-dimensional orthogonal coordinates.

  1 and 2, reference numeral 2 denotes a lens holder made of molded resin. The objective lens 1 is mounted on the lens holder 2, and is substantially along the focusing direction F at a position avoiding the objective lens 1. A rectangular through hole is drilled. A printed coil 3 is attached to a substantially central portion of the lens holder 2 in parallel to a plane including the focusing direction F and the tracking direction T.

  The printed coil 3 has a coil structure in which a conductive material is spirally attached around an axis parallel to the direction K on the substrate to form a coil structure, and the layers constituting the focusing coil portion 3a and the tracking coil portions 3b and 3c are arranged. Consists of two types of layers. The focusing coil portion 3a is disposed on the side closer to the objective lens 1, the tracking coil portions 3b and 3c are disposed on the side far from the objective lens 1, and the tracking coil portions 3b and 3c are wired in series.

  Further, the relay terminal plate 9 is fixed to each of the two side surfaces perpendicular to the tracking direction T of the lens holder 2, and both end terminals of the focusing coil 3a formed on the printed coil 3 and both ends of the tracking coil portions 3b and 3c. The terminals are connected by soldering.

  Therefore, the objective lens 1, the lens holder 2, the print coil 3, and the relay terminal plate 9 constitute a movable body. The movable body has a symmetrical shape with respect to a plane that includes the optical axis of the objective lens 1 and is perpendicular to the tracking direction T, and the center of gravity of the movable body is on a line that intersects the surface of the printed coil 3 on the plane. It is set to be located.

  Reference numeral 4 denotes a first multipole magnet having a plurality of magnetic pole regions on the same surface, and is composed of two magnetic pole regions, a magnetic pole region 4a and a magnetic pole region 4b, separated by one magnetic field boundary line parallel to the tracking direction T. ing.

  Reference numeral 5 denotes a second multipole magnet having a plurality of magnetic pole regions on the same surface, which is formed by combining two magnetic field boundary lines substantially parallel to the focusing direction F and one magnetic field boundary line parallel to the tracking direction T. It is composed of two magnetic pole areas, a quadrangular magnetic pole area 5a and a concave magnetic pole area 5b separated by a magnetic field boundary.

  Reference numeral 6 denotes a base, and the difference in shape is as shown in FIG. 1. Compared to the conventional one shown in FIG. 5, the side holes are formed longer or cuts are provided to increase the strength. It is weakening.

  The first multi-pole magnet 4 and the second multi-pole magnet 5 are arranged at a position where the printed coil 3 is sandwiched with a gap and close to the objective lens 1, and the first multi-pole magnet 4 is arranged in the mounting portion 6 a. On the far side, the second multi-pole magnet 5 is disposed on the mounting portion 6 b and is fixed to the base 6.

  The opposing magnetic pole surfaces of the magnetic pole region 4a of the first multipolar magnet 4 and the magnetic pole region 5a of the second multipolar magnet 5 are respectively S and N poles, and the different polarities face each other. Yes. Similarly, the magnetic pole surfaces 4b of the first multipole magnet 4 and the magnetic pole regions 5b of the second multipole magnet 5 that are partially opposed to each other are N-pole and S-pole, respectively, so that the different poles face each other. Is arranged.

  In the focusing coil portion 3a, the effective coil region 3a1 contributing to the focusing drive is opposed to the magnetic pole region 4a of the first multipole magnet 4, and the effective coil region 3a2 is opposed to the magnetic pole region 4b of the first multipole magnet 4. Yes.

  In the tracking coil portion 3b, the effective coil region 3b1 that contributes to tracking drive is opposite to the magnetic pole region 5a of the second multipole magnet 5, and the effective coil region 3b2 is opposite to the magnetic pole region 5b of the second multipole magnet 5. Similarly, in the tracking coil portion 3c, the effective coil region 3c1 that contributes to tracking driving is the magnetic pole region 5a of the second multipole magnet 5, and the effective coil region 3c2 is the magnetic pole region 5b of the second multipole magnet 5. And facing each other.

  The width dimension M in the tracking direction T of the first multipole magnet 4, the width dimension N in the tracking direction T of the second multipole magnet 5, and the tracking direction of the mounting portion 6 a of the first multipole magnet 4. The relationship of the width dimension L is L <M <N.

  A total of four wires 7a to 7d are connected by soldering to the two relay terminal plates 9 to which both terminals of the focusing coil portion 3a and both terminals of the tracking coil portions 3b and 3c are connected. 7 d is soldered to a fixed substrate 10 attached to a suspension holder 8 fixed to the base 6.

  The wires 7a to 7d are made of an elastic metal material such as beryllium copper or phosphor bronze, and wires or rods having a cross-sectional shape such as a circle, a substantially polygon, or an ellipse are used. Further, the support center of the wires 7a to 7d is set to substantially coincide with the center of gravity of the movable body.

  Next, the operation of the objective lens driving apparatus configured as described above will be described with reference to FIGS. 3 (a), 3 (b), and 3 (c).

  First, the driving operation of the movable body in the focusing direction F will be described.

  In FIG. 3C, when a current is passed through the focusing coil portion 3a in the direction of the arrow shown in the figure, the magnetic pole region 4a facing the effective coil region 3a1 is the S pole, and the magnetic pole region 4b facing the effective coil region 3a2 is the N pole. Therefore, a driving force in the arrow direction Pf is generated in the effective coil regions 3a1 and 3a2 of the focusing coil portion 3a. That is, the lens holder 2 is driven in the focusing direction F by the driving force Pf generated in the focusing coil portion 3a.

  Next, the driving operation of the movable body in the tracking direction T will be described.

  In FIG. 3A, when a current is passed through the tracking coil portions 3b and 3c in the direction of the arrow shown in the drawing, the effective coil region 3b1 and the magnetic pole region 5a facing the effective coil region 3c1 are the N pole, the effective coil region 3b2, and the effective coil. Since the magnetic pole region 5b facing the region 3c2 is the S pole, a driving force in the arrow direction Pt is generated in each of the effective coil regions 3b1, 3b2, 3c1, and 3c2 of the tracking coil portions 3b and 3c. That is, the lens holder 2 is driven in the tracking direction T by the driving force Pt generated in the tracking coil portions 3b and 3c.

  When the unnecessary resonance generated in the base when the objective lens driving device according to the present embodiment is driven in the focusing direction and the tracking direction is obtained by simulation, the unnecessary resonance generated in the base is obtained as shown in FIG. It can be seen that they are distributed. That is, unnecessary resonance does not spread to the whole, and only the vicinity where the first and second multipolar magnets 4 and 5 in the figure are attached is whitish, and the strength of the base 6 is lowered, so that unnecessary resonance is suppressed. I understand that.

  From the above driving operation, is it possible to disperse unnecessary resonance by reducing the strength of the base 6 in the portion where the first multipole magnet 4 and the second multipole magnet are attached, and to reduce unnecessary resonance? it can.

  Further, although the printed coil 3 in which the focusing coil portion 3a and the tracking coil portions 3b and 3c are integrally formed is used as a component constituting the focusing coil and the tracking coil, the focusing coil and the tracking coil are independently configured. Needless to say, the same effect can be obtained even when, for example, a wound coil is used.

  In the first embodiment, the constituent elements constituting the supporting means are the wires 7a to 7d, but the same effect can be obtained regardless of the supporting means.

  Further, although a multipolar magnet is used for the magnet configuration, it goes without saying that the same effect can be obtained even when a magnet that is not multipolarly magnetized is used.

  It is possible to disperse the vibration of the base that occurs during driving in the focusing direction and the tracking direction, and to reduce unnecessary resonance.

  Therefore, stable characteristics can be obtained in the objective lens driving device.

  The objective lens driving device according to the present invention disperses vibrations of the base generated during driving in the focusing direction and the tracking direction by weakening the strength of the base portion to which the first multipole magnet and the second multipole magnet are attached. Can reduce unnecessary resonance, and drives an objective lens driving device of an optical head mounted on an optical disk device for optically recording or reproducing information on a disc-shaped recording medium, driving in a focusing direction and a tracking direction This is useful as an objective lens driving device in which unnecessary resonance does not occur.

1 is an exploded perspective view showing a configuration of an objective lens driving device according to Embodiment 1 of the present invention. The top view which shows the structure of the objective lens drive device Side view and plan view showing the positional relationship between the tracking coil section of the objective lens driving device and the first and second multipole magnets Schematic diagram showing the result of simulation when the objective lens driving device is driven An exploded perspective view showing a configuration of a conventional objective lens driving device The top view which shows the structure of the conventional objective lens drive device Side view and plan view showing the positional relationship between the tracking coil section of the conventional objective lens driving device and the first and second multipole magnets Schematic diagram showing the result of simulation when a conventional objective lens driving device is driven

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3 Print coil 3a Focusing coil part 3b, 3c Tracking coil part 4 1st multipole magnet 5 2nd multipole magnet 6 Base 7a-7b Wire 8 Suspension holder 9 Relay terminal board 10 Fixed board | substrate

Claims (1)

A movable body having an objective lens having an optical axis in a focusing direction that is perpendicular to the disk and a lens holder that holds the objective lens, a base, and the movable body with respect to the base in the focusing direction and the disk It comprises a supporting means that elastically supports it so as to be movable in the tracking direction, which is a radial direction, a focusing coil and a tracking coil that are attached to substantially the center of the lens holder, and a first magnet and a second magnet fixed to the base. An objective lens driving device configured to dispose the objective lens at a position shifted from the center of the movable body,
The focusing coil and the tracking coil are flat coils each having a winding axis in a direction perpendicular to the focusing direction and the tracking direction,
The base includes the first magnet on the side closer to the objective lens and the second side on the far side so as to sandwich the focusing coil and the tracking coil with a gap along the winding axis direction. An objective lens driving device characterized in that a magnet is arranged to weaken the strength of the base portion of the first magnet and the second magnet mounting portion.

Images