JP3903434B2 - Objective lens drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an objective lens driving device for adjusting the position of an objective lens at least in a focus direction and a tracking direction in an optical pickup apparatus that records and reproduces information on an optical disk such as a CD, DVD, MD, which is a recording medium.
[0002]
[Prior art]
An optical pickup device that constitutes an optical disk device is generally composed of an objective lens driving device having an objective lens and an optical system that transmits and receives light to the objective lens, and is movably mounted in the radial direction (tracking direction) of the optical disk. The objective lens driving device is mounted on an optical system block mounting base.
[0003]
A conventional objective lens driving device includes a lens holder that holds an objective lens, a movable part that includes a focus coil and a tracking coil, and a fixed part that includes a magnetic circuit. The movable part is partially viscoelastic. It is supported by the fixing portion via four wires surrounded and held by a damper material.
[0004]
Patent Document 1 discloses a lens holder provided with a through hole into which a rising piece provided on a base and a magnet fixed to the rising piece are inserted through a gap at both ends of the lens holder. The lens holder is movable in the tracking direction by the gap in the tracking direction between the through hole and the magnet, etc., and the magnet or the like abuts against the inner wall of the through hole, so that the operating range of the lens holder in the tracking direction is increased. It has a configuration that functions as a stopper by limiting. For the focus direction, another means for limiting the operation range in the focus direction is provided. Such an operating range limiting means is provided to protect the wire indicating the lens holder and its mounting portion and to prolong the life.
[0005]
[Patent Document 1]
JP 2002-140828 A.
[0006]
[Problems to be solved by the invention]
In the conventional objective lens driving device, since the tracking direction stopper mechanism by the contact between the inner wall of the through hole and the magnet, and the other focus direction stopper mechanism are provided, the structure becomes complicated. There is a problem.
[0007]
In view of the above problems, an object of the present invention is to provide an objective lens driving device having an operation limiting mechanism for a movable part with a simple configuration.
[0008]
[Means for Solving the Problems]
(1) The objective lens driving device of the present invention includes a base and a fixed portion having a magnet mounted on the base,
A lens holder holding an objective lens, and a movable part having at least a focus coil and a tracking coil attached to the lens holder;
The fixing portion has two rising pieces for attaching magnets on the base with a gap in the tangential direction of the optical disc, and magnets having a rectangular parallelepiped shape are attached to the rising pieces for attaching magnets so as to face each other. Configured,
The movable part is located between the opposing magnets;
By fixing the other end of the wire having one end attached to the wire attaching portion fixed to the base to the lens holder, the movable portion is supported by the fixed portion via the wire and at least in the focus direction and the tracking direction. A movable objective lens driving device,
Protruding to the opposite side of the wire attachment part on both sides of the lens holder on the opposite side of the wire attachment part, and providing a gap between both sides of the magnet on the opposite side of the wire attachment part. Providing a first stopper for limiting the operating range of the movable portion in the tracking direction;
By providing a second stopper for restricting the operating range in the focusing direction on the magnet mounting rising piece on the opposite side of the wire mounting portion, with a gap in the focusing direction with respect to the first stopper, The first stopper is also used as an operating range limiting means in the focus direction.
[0009]
(2) Moreover, the objective lens driving device of the present invention is the objective lens driving device according to (1),
Wherein each magnet has two L-shaped magnetized portion which is magnetized in reverse polarity to the tangential direction consists of a parallel horizontal section to the vertical section and the optical disk for perpendicular with respect to the optical disc, respectively,
The focus coil is constituted by a coil wound in a substantially quadrilateral shape and is fixed to both end faces of the lens holder,
The tracking coil is wound around the lens holder in a headband shape so that the vertical winding portion is located on both sides of the focus coil mounting portion on both end faces of the lens holder and the horizontal winding portion is located on the upper and lower surfaces of the lens holder. ,
And a tilt coil for correcting the tilt of the lens holder in the radial direction of the optical disk, wherein the tilt coil is wound in a headband shape on both side surfaces and both end surfaces of the lens holder. To do.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 is a side view showing an embodiment of an objective lens driving device according to the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a perspective view showing a movable portion including the lens holder, and FIG. It is a perspective view which shows the combination structure of a part and a magnet.
[0012]
1 to 3 and 4A, reference numeral 1 denotes a lens holder that holds an objective lens 2. The lens holder 1 has a relatively high bending elastic modulus such as a resin containing reinforcing fibers or a magnesium alloy. Constructed from lightweight material. Reference numeral 3 denotes a base attached to an optical system block (not shown) provided to be movable in the radial direction of the optical disk. The base 3 and the lens holder 1 have an opening (not shown) for transmitting and receiving laser light between the optical system block, the objective lens 2 and the optical disk 27. In the present embodiment, the base 3 is made of a magnetic material such as iron and has a yoke function.
[0013]
Reference numerals 4a, 4b, and 4c denote wires that support the lens holder 1 and have a function of energizing focus coils 5a and 5b, tracking coils 6a and 6b, and tilt coils 7a and 7b, which will be described later, provided on the lens holder 1. Three wires 4 a to 4 c are provided on both sides of the lens holder 1. One end side of these wires 4 a to 4 c is fixed to a wire attaching portion 8 fixed to the base 3. The wire attaching portion 8 includes a damper material accommodation block 9 and a printed board 11 fixed to the damper material containing block 9 with screws 10. The wires 4 a to 4 c penetrate so as to be held by the damper material accommodated in the damper material accommodation block 9, and are inserted into the holes of the printed board 11 and soldered to be fixed. The other ends of the wires 4a to 4c are fitted in grooves 13 of positioning projections 12a to 12c provided on the side of the lens holder 1 and fixed by an adhesive 14 (see FIG. 1), and the coils 5a, The terminals 5b, 6a, 6b, 7a and 7b are fixed to terminal winding protrusions 15a to 15c by solder 17 (see FIG. 1) and electrically connected to the terminals of the coils.
[0014]
In FIG. 2, an arrow S indicates the tangential direction of the optical disk, and an arrow T indicates the tracking direction. In the present embodiment, the focus coils 5a and 5b are substantially spirally wound in a substantially quadrilateral shape, and are attached to both end surfaces in the tangential direction of the optical disk indicated by the arrow S in the lens holder 1. Further, the tracking coils 6a and 6b are wound in a headband shape across the both end surfaces and the upper and lower surfaces of the lens holder 1 so that the vertical winding portions are positioned on both sides of the focus coils 5a and 5b on the end surface of the lens holder 1.
[0015]
The tilt coils 7a and 7b are wound around the outer periphery of the lens holder 1, that is, from both side surfaces to both end surfaces, in grooves provided in two upper and lower stages on each surface. The focus coils 5a and 5b and the tracking coils 6a and 6b are overlaid on the outer surfaces of the tilt coils 7a and 7b.
[0016]
Reference numerals 16a and 16b denote magnets fixed to the rising pieces 3a and 3b provided on the base 3 by bonding or the like so as to face both end faces of the lens holder 1 in the optical disc tangential direction. These magnets 16a and 16b are rectangular parallelepiped, and are composed of two magnetized portions 19 and 20 magnetized in an L shape and magnetized portions 21 and 22.
[0017]
FIG. 4B is a diagram showing magnetized portions 19 to 22 of the magnets 16a and 16b. The magnetized portions 19 and 20 of the magnet 16a include vertical portions a and c that are perpendicular to the optical disc, and horizontal portions b and d that are parallel to the optical disc, respectively. The horizontal portions b and d are combined so as to be parallel to each other.
[0018]
Similarly, the magnetized portions 21 and 22 of the magnet 16b include vertical portions e and g that are perpendicular to the optical disc, and horizontal portions f and h that are parallel to the optical disc, respectively. The horizontal portions f and h of 22 are combined so as to be parallel to each other.
[0019]
Reference numeral 25 denotes a flexible printed circuit board (FPC) for connecting to a circuit of an optical system block (not shown) to the wiring of the printed circuit board 11.
[0020]
FIG. 5 is a plan view showing the positional relationship between the coil and the magnets 16a and 16b. 6, 7, and 8 are views seen in the X direction of FIG. 5, and the arrangement relationship between the coil and the magnet and the relationship between the energization current and the driving force are shown for the focus coil, tracking coil, and tilt coil, respectively. It is shown.
[0021]
FIG. 6A shows a facing portion between the focus coil 5a and the magnet 16a. As can be seen from FIG. 5, the upper half 5a1 of the focus coil 5a faces the S pole of the horizontal part d above the magnetized part 20, so that the magnetic flux is changed from the back side to the front side in FIG. When the current i1 flows in the upper half portion 5a1, the force f1 that drives the lens holder 1 in the upper direction on the paper surface, that is, in the direction close to the optical disc, is generated according to Fleming's left-hand rule. At this time, a current i2 (= i1) in the opposite direction to the upper half 5a1 flows in the lower half 5a2 of the focus coil 5, and the N of the horizontal portion b below the magnetized portion 19 flows in the lower half 5a2. Since the poles face each other, the magnetic flux is directed from the front surface to the back surface of the paper, and the lower half 5a2, that is, the lens holder 1, generates a force f2 that is also driven upward.
[0022]
FIG. 6B shows a facing portion between the focus coil 5b and the magnet 16b. As shown in the figure, the N pole of the horizontal portion f on the magnetized portion 21 faces the upper half portion 5b1 of the focus coil 5b. The S pole of the horizontal portion h below the magnetized portion 22 faces the lower half portion 5b2 of the focus coil 5b. For this reason, when the currents i1 and i2 flow through the focus coil 5a, the focus coil 5b is wound so that the currents i3 and i4 having the same values as those currents flow in the direction shown in the drawing in the focus coil 5b. These currents generate forces f3 and f4 for driving the lens holder 1 upward in the upper half 5b1 and the lower half 5b2.
[0023]
When a current flows in a direction opposite to these currents i1 to i4, a driving force in a direction away from the disk is generated according to the current value, opposite to f1 to f4, respectively.
[0024]
FIG. 7A shows a facing portion between the tracking coils 6a and 6b and the magnet 16a. The vertical winding portion 6a1 of the tracking coil 6a faces the N pole of the vertical portion a of the magnetized portion 19 of the magnet 16a. Further, the vertical winding portion 6b1 of the tracking coil 6b faces the S pole of the vertical portion c of the magnetized portion 20 of the magnet 16a. Therefore, when currents i5 and i6 (i5 = i6) are passed through the tracking coils 6a and 6b in the direction shown in the drawing, the lens holder 1 is driven in the same direction in the longitudinal windings 6a1 and 6b1 of the tracking coils 6a and 6b. Driving forces tr1 and tr2 are generated.
[0025]
FIG. 7B shows a facing portion between the tracking coils 6a and 6b and the magnet 16b. The vertical winding portion 6a2 of the tracking coil 6a faces the N pole of the vertical portion e of the magnetized portion 21 of the magnet 16b. In addition, the vertical winding portion 6b2 of the tracking coil 6b faces the S pole of the vertical portion g of the magnetized portion 22 of the magnet 16b. Therefore, when currents i7 and i8 (= i5 = i6) are passed through the tracking coils 6a and 6b in the direction shown in the drawing, the lens holder 1 is driven in the same direction in the longitudinal windings 6a2 and 6b2 of the tracking coils 6a and 6b. Driving forces tr3 and tr4 are generated.
[0026]
When a current flows in a direction opposite to these currents i5 to i8, a driving force in the tracking direction T is generated in accordance with the current value, opposite to tr1 to tr4, respectively.
[0027]
FIG. 8A shows a facing portion between the tilt coils 7a and 7b and the magnet 16a. As shown in the drawing, when currents i9 and i10 (i9 = i10) are passed through the facing portions 7a1 and 7b1 of the tilt coils 7a and 7b facing the magnet 16a in the illustrated directions, the vertical portions on both sides of the magnetized portions 19 and 20 respectively. Due to the interlinkage with the magnetic fluxes at a and c, the driving forces t1 and t2 in the opposite directions are generated in the tilt coils 7a and 7b in both side portions of the drawing. On the other hand, in the central portion 26, the driving forces generated at the facing portions 7a1 and 7a2 with the magnets 16a of the tilt coils 7a and 7b are canceled out, so that only the driving forces t1 and t2 on both sides remain and eventually the tilt direction A driving force acts on the lens holder 1.
[0028]
FIG. 8B shows a facing portion between the tilt coils 7a and 7b and the magnet 16b. As shown in the figure, when currents i11 and i12 (= i9 = i10) are passed through the facing portions 7a2 and 7b2 of the tilt coils 7a and 7b facing the magnets 16b in the direction shown in the drawing, both sides of the magnetized portions 21 and 22 are perpendicular. Driving forces t3 and t4 in opposite directions are generated in the tilt coils 7a and 7b by the linkage with the magnetic flux in the parts e and g at opposite side portions of the drawing. On the other hand, in the central portion 26, the driving forces generated in the upper half and the lower half are canceled in the same manner as the facing portion with the magnet 16a, so that only the driving forces t3 and t4 on both sides remain after all. A driving force in the tilt direction acts on the lens holder 1. Accordingly, the driving forces t1 and t3 on the right side in the drawing are applied, and the driving forces t2 and t4 on the left side are applied, so that the driving force in the tilt direction acts on the lens holder 1.
[0029]
When a current flows in a direction opposite to these currents i9 to i12, a driving force in the tilt direction is generated in accordance with the current value, opposite to t1 to t4, respectively.
[0030]
Next, the operation range limiting mechanism of the lens holder 1 according to the present invention will be described. 1 to 4, reference numeral 23 denotes a first stopper for restricting the operating range in the focus direction, which protrudes on both sides of the magnet 16 a from a projection 15 b on the coil terminal fixing intermediate portion provided on both sides of the lens holder 1. It is. These first stoppers 23 have a gap g1 and the surfaces on both sides of the magnet 16a (which may be a second stopper 24 described later) as shown in FIG. 9 when the lens holder 1 is in the neutral position in the tracking direction. Thus, the lens holder 1 is provided on both sides of the lens holder 1 opposite to the wire attachment portion 8 so as to protrude to the opposite side of the wire attachment portion 8 . Accordingly, when the lens holder 1 moves in the tracking direction by the gap g1, one of the two first stoppers 23 comes into contact with the side surface of the lens holder 1 and the lens holder 1 moves excessively in the tracking direction. To prevent.
[0031]
As shown in FIGS. 1 and 2, a second stopper 24 that restricts the operating range of the first stopper 23 in the focus direction is fixed to the rising piece 3a and the magnet 16a. As shown in FIG. 9, the second stopper 24 has gaps above and below the first stopper 23 at portions located on both sides of the magnet 16 a when the first stopper 23 is in the neutral position in the focus direction. It has a protrusion 24a that is an upper limit position setting and a protrusion 24b that is a lower limit position setting portion that face each other via g2. Accordingly, when the lens holder 1 moves from the neutral position in the focus direction by the gap g2 in the focus direction, the first stopper 23 comes into contact with either of the protrusions 24a and 24b and the lens holder 1 excessively moves in the focus direction. Prevent moving.
[0032]
These stopper mechanisms prevent the lens holder 1 from moving excessively in the focus direction and the tracking direction and damaging or shortening the wires 4a to 4c and their mounting portions. Further, in the present embodiment, since one first stopper 23 is also used as an operation restricting unit in the focus direction and the tracking direction, the configuration of the stopper mechanism is simplified. Further, as in the present embodiment, the magnets 16a and 16b are magnetized in two L-shapes, and the focus coils 5a and 5b and the tracking coils 6a and 6b are vertically mounted on the lens holder 1 as the winding structure and mounting structure. Since the through hole is not required, the size can be reduced.
[0033]
FIG. 10A is a side view showing another embodiment of the present invention, and FIG. 10B is a diagram showing the positional relationship between the first stopper and the second stopper. In the present embodiment, two first stoppers 23a and 23b are provided so as to protrude from the upper and lower sides of the lens holder 1 on both sides of the magnet 16a. These first stoppers 23a and 23b have a gap g1 between the side surfaces of the magnet 16a when the lens holder 1 is in the neutral position in the tracking direction. On the other hand, the second stopper 24 provided on the rising piece 3a and the magnet 16a has a protrusion 24c located between the first stoppers 23a and 23b. When the lens holder 1 is in the neutral position in the focus direction, the gap g2 between the protrusion 24c and the stoppers 23a and 23b is set to be equal. Even with such a configuration, the configuration of the stopper mechanism can be simplified as in the above embodiment.
[0034]
Incidentally, the opposite to the respective embodiments, the stopper protrudes from the rising piece 3a and the magnet 16a side to the lens holder 1 side is provided, Rukoto provided focusing direction limit to the lens holder 1 side, the setting means lower limit position Is also possible. However, since the lens holder 1 is provided with various coils, the first stopper 23 or 23a, 23b is protruded from the lens holder 1 toward the magnet 16a as in the embodiment shown in FIGS. Therefore, it is possible to realize a structure in which orderly assembly is easy.
[0035]
【The invention's effect】
According to the present invention, either one of the fixed portion and the movable portion is provided with a tracking direction operation range limiting stopper that protrudes to the other side, and the stopper is provided with an operating range in the focus direction provided on the other side. Since the operating range in the focus direction is limited to face the limiting portion via a gap, the configuration for limiting the operating range is simplified.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of an objective lens driving device according to the present invention.
2 is a plan view of FIG. 1. FIG.
FIG. 3 is a perspective view showing a movable part including a lens holder according to the present embodiment.
4A is a perspective view showing a combined structure of a movable part and a magnet according to the present embodiment, and FIG. 4B is a perspective view showing a magnetized structure of the magnet.
FIG. 5 is a plan view showing a positional relationship between a coil and a magnet according to the present embodiment.
6 is a view taken in the direction of arrow X in FIG. 5 showing the relationship between the focus coil and the magnet in the present embodiment.
7 is a view taken along the arrow X in FIG. 5 showing the relationship between the tracking coil and the magnet in the present embodiment.
FIG. 8 is a view taken in the direction of arrow X in FIG. 5 showing the relationship between the tilt coil and the magnet in the present embodiment.
FIG. 9 is a diagram showing a positional relationship of stoppers in the present embodiment.
10A is a side view showing another embodiment of the present invention, and FIG. 10B is a diagram showing the positional relationship of the stoppers.
[Explanation of symbols]
1: lens holder, 2: objective lens, 3: base, 4a to 4c: wire, 5a, 5b: focus coil, 6a, 6b: tracking coil, 7a, 7b: tilt coil, 8: wire mounting portion, 9: damper Material housing block, 10: screw, 11: printed circuit board, 12a-12c: positioning protrusion, 13: groove, 14: adhesive, 15a-15c: terminal winding protrusion, 16a, 16b: magnet, 17: solder, 19 -22: magnetized portion, 23, 23a, 23b: first stopper, 24: second stopper, 24a: upper limit position setting protrusion, 24b: lower limit position setting protrusion, 24c: protrusion, 25: flexible printed circuit board , S: tangential direction of optical disc, T: tracking direction

Claims (2)

A fixed part having a base and a magnet mounted on the base;
A lens holder holding an objective lens, and a movable part having at least a focus coil and a tracking coil attached to the lens holder;
The fixing portion has two rising pieces for attaching magnets on the base with a gap in the tangential direction of the optical disc, and magnets having a rectangular parallelepiped shape are attached to the rising pieces for attaching magnets so as to face each other. Configured,
The movable part is located between the opposing magnets;
By fixing the other end of the wire having one end attached to the wire attaching portion fixed to the base to the lens holder, the movable portion is supported by the fixed portion via the wire and at least in the focus direction and the tracking direction. A movable objective lens driving device,
Protruding to the opposite side of the wire attachment part on both sides of the lens holder on the opposite side of the wire attachment part, and providing a gap between both sides of the magnet on the opposite side of the wire attachment part. Providing a first stopper for limiting the operating range of the movable portion in the tracking direction;
By providing a second stopper for restricting the operating range in the focusing direction on the magnet mounting rising piece on the opposite side of the wire mounting portion, with a gap in the focusing direction with respect to the first stopper, The objective lens driving device according to claim 1, wherein the first stopper is also used as an operation range limiting unit in a focus direction. The objective lens driving device according to claim 1,
Wherein each magnet has two L-shaped magnetized portion which is magnetized in reverse polarity to the tangential direction consists of a parallel horizontal section to the vertical section and the optical disk for perpendicular with respect to the optical disc, respectively,
The focus coil is constituted by a coil wound in a substantially quadrilateral shape and is fixed to both end faces of the lens holder,
The tracking coil is wound around the lens holder in a headband shape so that the vertical winding portion is located on both sides of the focus coil mounting portion on both end faces of the lens holder and the horizontal winding portion is located on the upper and lower surfaces of the lens holder. ,
And a tilt coil for correcting the tilt of the lens holder in the radial direction of the optical disk, wherein the tilt coil is wound in a headband shape on both side surfaces and both end surfaces of the lens holder. Objective lens driving device.

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