JP2006085882A - Objective lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens driving device which has strong rigidity and can stably respond to a high frequency. <P>SOLUTION: In the objective lens driving device 1 provided with a lens holder 5 for holding an objecting lens 4 located between a pair of back yokes 3, 3 formed on a base 2, a pair of magnets 10, 10 located between the paired back yokes 3, 3 and the lens holder 5, a focus coil 6 wound along the periphery of the lens holder 5, and a tracking coil 9 arranged in the lens holder 5, counter yokes 7 of a pin shape or a flat plate are formed inside the paired magnets 10, 10 on the base 2 in the direction of connecting between the paired back yokes 3, 3, and through-holes 8 for housing the counter yokes 7 of a pin shape or a flat plate are formed in the lens holder 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an objective lens driving device used for an optical pickup for recording or reproducing an optical disk.

When recording / reproducing an optical disk, an objective lens driving device for focusing and tracking is used.
This objective lens driving device is described in Patent Document 1.

That is, a pair of yokes, a pair of permanent magnets provided inside the pair of yokes, a movable body supporting an objective lens provided between the pair of permanent magnets (first magnetic gap), and the movable Between the first and second focusing coils provided on the body and the first and second seek coils for winding the pair of yokes provided in a direction orthogonal to the pair of permanent magnets, and the pair of permanent magnets Can be moved in the radial direction of the disk by supporting the movable magnet and a permanent magnet disposed opposite to the pair of yokes so that one side passes through a second magnetic gap having a magnetic field direction orthogonal to the magnetic field direction It is described that it can improve the working frequency band of the focus, increase the driving force in the seek direction, and move between tracks at high speed.

Further, as shown in FIG. 10, an objective lens driving device having an opening 18A at both ends of the lens holder 18 and a U-shaped yoke 23 having a permanent magnet 24 inside the opening 18A. There are 16 as well.
Specifically, the objective lens driving device 16 includes a lens holder 1 in which an objective lens 17 is placed at the center and a pair of openings 18A and 18A are formed so as to sandwich the objective lens 17 therebetween.
8, a focus coil 19 wound along the side surface of the lens holder 18, and a pair of tracking coils 20 formed in the side surface of the lens holder 18 in a direction connecting the pair of openings 18 </ b> A and 18 </ b> A, 20, a pair of printed circuit boards 21 and 21 formed on both side surfaces of the lens holder 18 different from the surface on which the pair of tracking coils 20 and 20 are formed, and four attached to the pair of printed circuit boards 21 and 21 A suspension spring 22, and a pair of openings 18 </ b> A and 18 </ b> A of the lens holder 18 is provided with a U-shaped permanent magnet 24 having a U-shape and having one end housed in the yoke 23.
With this configuration, the magnetic flux density that passes through the focus coil 19 and the pair of tracking coils 20 and 20 can be increased, so that the sensitivity of the lens holder 18 can be increased.
On the other hand, Patent Document 2 describes that the U-shaped yoke 23 shown in FIG. 10 as described above is configured not to penetrate the lens holder 18.
Japanese Patent Laid-Open No. 5-15133 Japanese Patent Laid-Open No. 2003-15209

However, in the case of the objective lens driving device shown in Patent Document 1, the rigidity of the objective lens driving device is low because of the first magnetic gap. Further, in the case of the objective lens driving device shown in FIG. 10, since the lens holder 18 has an opening, the rigidity of the lens holder 18 is low and the high-order resonance frequency cannot be increased. As a result, stable tracking up to a high frequency could not be performed. Further, as described in Patent Document 2, since the U-shaped yoke 23 is configured not to protrude the lens holder 18, the overlap between the yoke 23 and the focus coil becomes a part, so that the magnetic flux leakage Was produced. As a result, the sensitivity of the lens holder could be increased only slightly.

Therefore, the present invention has been proposed in view of the above-described problems, and an object thereof is to provide an objective lens driving device that has high rigidity and can stably follow a high frequency.

According to a first aspect of the present invention, a lens holder that supports an objective lens disposed in the center between a pair of back yokes formed on a base, and is placed between the pair of back yokes and the lens holder. A pair of magnets, a focus coil wound around the periphery of the lens holder, and a tracking coil provided on a side surface of the lens holder in a direction connecting the pair of back yokes. In the objective lens driving device that moves the lens holder with respect to the disk by the interaction between the magnetic field generated by the current and the current flowing through the focus coil and the tracking coil, a direction in which the pair of back yokes are connected on the base And a plurality of pin-shaped or flat counter-shaped yokes are formed inside the pair of magnets. , The lens holder provides an objective lens driving device, wherein a through hole for accommodating a plurality of pin-like or plate-shaped counter yokes are formed.
According to a second aspect of the present invention, there is provided a lens holder that supports an objective lens disposed in the center between a pair of back yokes formed on a base, and a pair that is placed between the pair of back yokes and the lens holder. Magnetic field generated by the pair of magnets, a focus coil wound around the periphery of the lens holder, and a tracking coil provided on a side surface of the lens holder in a direction connecting the pair of back yokes And an objective lens driving device for moving the lens holder relative to the disk by the interaction between the current flowing in the focus coil and the tracking coil, and the lens holder is formed with a recess parallel to the pair of back yokes. One end is fixed on the base, and the pair of back yokes and the magnets Covering the section and side, and the other end to provide an objective lens driving apparatus characterized by shield portion of the recess at the bottom thereof is housed so as not to contact the the U-shape is formed.
According to a third aspect of the present invention, there is provided a lens holder that supports an objective lens disposed in the center between a pair of back yokes formed on a base, and a pair that is placed between the pair of back yokes and the lens holder. Magnetic field generated by the pair of magnets, and a focus coil wound around the periphery of the lens holder and a tracking coil provided on a side surface of the lens holder in a direction connecting the pair of back yokes And an objective lens driving device for moving the lens holder relative to the disk by the interaction between the current flowing in the focus coil and the tracking coil, and on the base, in a direction connecting the pair of back yokes. A plurality of pin-shaped or flat counter yokes are formed inside the pair of magnets; The holder is provided with a storage portion that stores one of the plurality of pin-shaped or flat plate-shaped counter yokes, and an upper end of the plurality of pin-shaped or flat plate-shaped counter yokes that is stored in the storage portion is the tracking member. Provided is an objective lens driving device which is flush with the upper end of a coil.

According to the present invention, on the base, a plurality of pin-shaped or flat counter yokes are formed inside the pair of magnets in a direction connecting the pair of back yokes. Since the through holes for accommodating the plurality of pin-shaped or flat plate-shaped counter yokes are formed, it is possible to stably follow the high frequency range.
Further, the lens holder is formed with a recess parallel to the pair of back yokes, one end is fixed on the base, covers the pair of back yokes and the upper and side surfaces of the magnet, and the other end is the Since the U-shaped shield part that is housed in the recess so as not to contact the bottom part is formed, the tip of the vertical part of the shield comes into contact with the bottom part of the recess when the lens holder is fully displaced upward. Therefore, the amount of upward displacement of the lens holder can be suppressed without requiring a special stopper.

Hereinafter, each embodiment of the objective lens driving device according to the present invention will be described in detail with reference to FIGS. 1 to 9.
FIG. 1 is a perspective view showing an objective lens driving device according to the first embodiment of the present invention.
FIG. 2 is a side view showing the objective lens driving apparatus according to the first embodiment of the present invention.
FIG. 3 is a diagram for explaining the flow of magnetic flux in the objective lens driving device according to the first embodiment of the present invention.
FIG. 4 is a perspective view showing an objective lens driving apparatus according to the second embodiment of the present invention.
FIG. 5 is a side view showing an objective lens driving apparatus according to the second embodiment of the present invention.
FIG. 6 is a diagram for explaining the flow of magnetic flux in the objective lens driving device according to the second embodiment of the present invention.
FIG. 7 is a perspective view showing an objective lens driving apparatus according to the third embodiment of the present invention.
FIG. 8 is a side view showing an objective lens driving apparatus according to the third embodiment of the present invention.
FIG. 9 is a diagram for explaining the flow of magnetic flux in the objective lens driving device according to the third embodiment of the present invention.

First, the first embodiment will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the objective lens driving device 1 penetrates through a pair of back yokes 3, 3 formed on the base 2 and a central portion formed inside the pair of back yokes 3, 3. Hole 5
A lens holder 5 that houses the lens portion of the objective lens 4 in the through-hole 5A and supports both ends thereof, a focus coil 6 wound along the side surface of the lens holder 5, and a base 2 A total of four pin-shaped counter yokes 7 which are arranged on the inside of the pair of back yokes 3 and 3 and are formed two for each back yoke 3. The lens holder 5 is formed with a total of four through-holes 8 for accommodating a total of four pin-shaped counter yokes 7. These total four through-holes 8 are total when the lens holder 5 is displaced to the maximum. The four pin-like counter yokes 7 are made as small as possible so as not to interfere with the lens holder 5.

Further, a pair of tracking coils 9 and 9 formed on the side surface of the lens holder 5 in a direction connecting the pair of back yokes 3 and 3 of the lens holder 5 and a pair of the tracking coils 9 and 9 on the base 2, A pair of magnets 10 and 10 having the same polarity, which are bonded and fixed between the back yokes 3 and 3, and the base 2, outside the back yoke 3 of one of the pair of back yokes 3 and 3. And a suspension base 11 formed.
The lens holder 5 is connected to a suspension base 11 via suspension springs 12 and 12.
And is movable up and down and left and right along with the movement of the suspension spring 12.

Next, the operation will be described with reference to FIG.
Due to the interaction between the current passed through the focus coil 6 and the pair of tracking coils 9, 9 and the magnetic field generated by the pair of magnets 10, 10, the recording / reproducing light incident on the objective lens 4 is focused on the disk by the focus coil 6. Direction and tracking coil 9
The lens holder 5 is moved via the suspension springs 12 and 12 by applying a force in the tracking direction (disc radial direction) to the disc 9. Thus, focus and tracking can be taken.
At this time, as shown in FIG. 3, the magnetic flux generated by the pair of magnets 10, 10 can be collected in the four opposing yokes 7, 7, 7, 7. Therefore, the focus coil 6 and the pair of tracking coils 9. , 9 can be increased, and the lens holder 5 can be moved at a high-order frequency, so that the lens holder 5 can be stably followed up to a high frequency range.

As described above, according to the first embodiment of the present invention, the pair of back yokes 3 on the base 2.
3 and a plurality of pin-shaped counter yokes 7 arranged opposite to each other, and a plurality of through-holes 8 for accommodating the plurality of pin-shaped counter yokes 7 formed in the lens holder 5, so that the rigidity is strong, Stable tracking up to high frequency range.
Note that a flat counter yoke may be used instead of the pin-shaped counter yoke 7. In this case, the through hole 8 may have a shape that accommodates the flat counter yoke.

Next, a second embodiment of the present invention will be described with reference to FIGS.
The same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIGS. 4 and 5, the objective lens driving device 13 of the second embodiment is a pair of instead of the through holes 8 formed in the lens holder 5 of the objective lens driving device 1 of the first embodiment. A concave portion 14 having a predetermined width parallel to the back yokes 3 and 3 and having a predetermined depth is formed, and one end is bonded and fixed on the base 2 instead of the opposing yoke 7, and the back yokes 3 and 3, the magnet 10, 10 has a U-shaped shield portion 15 that is stored in the concave portion 14 of the lens holder 5 so that the other end does not contact the bottom thereof, and the other end of the shield 15 accommodated in the concave portion 14 is covered. A vertical portion 15A is formed, and the rest is the same.

As shown in FIG. 6, since the magnetic flux generated by the pair of magnets 10 and 10 can be collected in the vertical portion 15A of the shield portion 15, the magnetic flux density passing through the focus coil 6 and the pair of tracking coils 9 and 9 is reduced. The lens holder 5 can be stably tracked up to a high frequency range.

According to the second embodiment, in addition to the effects of the first embodiment, the tip of the vertical portion 15A of the shield portion 15 is brought into contact with the bottom portion of the concave portion 14 when the lens holder 5 is maximum displaced upward. Therefore, the amount of upward displacement of the lens holder 5 can be suppressed without requiring a special stopper.

Next, a third embodiment of the present invention will be described with reference to FIGS.
The same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIGS. 7 and 8, the objective lens driving device 25 of the third embodiment is configured so that the pair of back yokes 23 of the objective lens driving device 16 shown in FIG. 10 do not protrude from the surface of the lens holder 5. A pair of back yokes 23 are provided. The lens holder 5 has a predetermined parallel width, and the opposing yoke 26 that is the tip of the pair of back yokes 23 and the upper ends of the pair of focus coils 6 are flush with each other. is there.

  Conventionally, when the tip of the opposing yoke 26 is not more than flush with the upper end of the focus coil 6, effective magnetic flux density cannot be collected, and from the upper end of the lens holder 5 as shown in FIG. When the opposing yoke 26 penetrates, the shielding effect is lost and magnetic flux density leakage occurs.

  On the other hand, as shown in FIG. 9, in the third embodiment of the present invention, a lens holder 5 that supports the objective lens 4 disposed at the center between a pair of back yokes 23 formed on the base 2. A pair of magnets 10 placed between the pair of back yokes 23 and the lens holder 5, a focus coil 6 wound around the lens holder 5, and a pair of back yokes 23. A tracking coil 9 provided on the side surface of the lens holder 5, and the lens holder 5 is movable with respect to the disk by the interaction between the magnetic field generated by the pair of magnets 10 and the current flowing through the focus coil 6 and the tracking coil 9. In the objective lens driving device 25 to be operated, the pair of magnets 10 are arranged on the base 2 in the direction connecting the pair of back yokes 23. A plurality of pin-shaped or flat plate-shaped counter yokes 26 are formed on the side, and the lens holder 5 is provided with a storage portion 27 for storing one of the plurality of pin-shaped or flat plate-shaped counter yokes 26. Magnetic flux density that allows the focus coil 6 and the pair of tracking coils 9 and 9 to pass through is configured such that the upper ends of the accommodated pin-shaped or flat counter yokes 26 are flush with the upper end of the tracking coil 5. Therefore, the sensitivity of the lens holder 5 can be increased.

It is a perspective view which shows the objective lens drive device which concerns on 1st Embodiment of this invention. It is a side view which shows the objective lens drive device which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the flow of the magnetic flux of the objective lens drive device which concerns on 1st Embodiment of this invention. It is a perspective view which shows the objective lens drive device which concerns on 2nd Embodiment of this invention. It is a side view which shows the objective lens drive device which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the flow of the magnetic flux of the objective lens drive device which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the objective lens drive device which concerns on 3rd Embodiment of this invention. It is a side view which shows the objective lens drive device which concerns on 3rd Embodiment of this invention. It is a figure for demonstrating the flow of the magnetic flux of the objective lens drive device which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the objective lens drive device of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 13, 25 ... Objective lens drive device, 2 ... Base, 3, 23 ... Back yoke, 4 ... Objective lens, 5 ... Lens holder, 5A, 8 ... Through-hole, 6 ... Focus coil, 7 ... Opposing yoke, 9 DESCRIPTION OF SYMBOLS ... Tracking coil, 10 ... Magnet, 11 ... Suspension base, 12 ... Suspension spring, 14 ... Recessed part, 15 ... Shield part, 15A ... Vertical part, 26 ... Back yoke end (opposite yoke), 27 ... Lens holder recessed part (storage part) )

Claims (3)

A lens holder that supports an objective lens disposed in the center between a pair of back yokes formed on the base, a pair of magnets placed between the pair of back yokes and the lens holder, and the lens holder A focus coil wound around the periphery of the lens, and a tracking coil provided on a side surface of the lens holder in a direction connecting the pair of back yokes,
An objective lens driving device that moves the lens holder relative to the disk by the interaction between the magnetic field generated by the pair of magnets and the current flowing through the focus coil and the tracking coil.
On the base, a plurality of pin-shaped or flat counter yokes are formed inside the pair of magnets in a direction connecting the pair of back yokes, and the lens holder includes the plurality of pin-shaped yokes. Alternatively, the objective lens driving device is characterized in that a through hole for accommodating the flat counter yoke is formed. A lens holder that supports an objective lens disposed in the center between a pair of back yokes formed on the base, a pair of magnets placed between the pair of back yokes and the lens holder, and the lens holder A focus coil wound around the periphery of the lens, and a tracking coil provided on a side surface of the lens holder in a direction connecting the pair of back yokes,
An objective lens driving device that moves the lens holder relative to the disk by the interaction between the magnetic field generated by the pair of magnets and the current flowing through the focus coil and the tracking coil.
The lens holder is formed with a recess parallel to the pair of back yokes, one end is fixed on the base, covers the pair of back yokes and the upper and side surfaces of the magnet, and the other end is the recess. An objective lens driving device, wherein a U-shaped shield portion is formed so as not to contact the bottom portion. A lens holder that supports an objective lens disposed in the center between a pair of back yokes formed on the base, a pair of magnets placed between the pair of back yokes and the lens holder, and the lens holder A focus coil wound around the periphery of the lens, and a tracking coil provided on a side surface of the lens holder in a direction connecting the pair of back yokes,
An objective lens driving device that moves the lens holder relative to the disk by the interaction between the magnetic field generated by the pair of magnets and the current flowing through the focus coil and the tracking coil.
On the base, a plurality of pin-shaped or flat counter yokes are formed inside the pair of magnets in a direction connecting the pair of back yokes, and the lens holder includes the plurality of pin-shaped yokes. Alternatively, a storage portion for storing one of the flat counter yokes is provided, and upper ends of the plurality of pin-shaped or flat counter yokes stored in the storage portion are flush with the upper ends of the tracking coils. An objective lens driving device.

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