JP2002092916A - Objective lens drive device of optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a dedicated magnet for adjusting the tilt of an objective lens in an objective lens drive device of an optical pickup. SOLUTION: A magnetic circuit including at least one magnet 5 magnetized in multipole is formed. A coil unit 3 on which a focus coil 3f, a tracking coil 3tr and a tilt coil 3ti are mounted is arranged in the magnetic gap 5g of the magnetic circuit. The tilt of the objective lens is also adjusted by the magnet 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device of an optical pickup which constitutes an optical disk device capable of optically reading information by projecting a light spot on a recording medium on a disk.

[0002]

2. Description of the Related Art An optical pickup constituting an optical disk apparatus generally comprises an objective lens driving device having an objective lens and an optical system for transmitting and receiving light to and from the objective lens. It has a structure in which an objective lens driving device is arranged. The objective lens driving device includes an objective lens, a focus coil, a movable unit including a tracking coil, and a fixed unit including a magnetic circuit.
The movable part is supported by the fixed part by four wires partially surrounded and held by an elastic damper material such as a viscoelastic material.

Japanese Patent Application Laid-Open No. 9-231595 discloses an objective lens driving device which not only drives the objective lens in the focusing direction and the tracking direction but also corrects coma aberration and astigmatism of a spot formed on a disk. Are known. This prior art is shown in FIGS.
As shown in FIG. 3, at least a pair of optical sensors 301 and 302 are provided on the optical disk facing surface of the lens holder 101 in the radial direction or the tangential direction of the optical disk of the objective lens 103.
In addition, a coil 105 for performing tilt correction is provided on one or both side surfaces of the lens holder 101 in the radial direction of the optical disc to perform tilt correction on the yokes 113 and 114 facing the side surface of the lens holder 101. A pair of magnet members 106 and 107 having opposite poles are provided in correspondence with the arrangement of the coil 105, and the inclination of the optical disk 100 is detected based on the outputs of the optical sensors 301 and 302. Coil 10 for performing tilt correction based on the calculated value of the deviation from the lens optical axis
5 is driven by a current, and the magnet members 106 and 107 of opposite polarity are driven.
The side surface of the lens holder 101 is driven by electromagnetic interaction with the lens holder, and servo control is performed so that the lens holder 101 can be tilted freely.

A pair of optical sensors 301 and 302 are attached to both sides of the objective lens 103 of the lens holder 101, and as shown in FIG. 22, are emitted from an optical head and diffracted by an optical disk groove. 201, 202
Is received. The electric signals from the optical sensors 301 and 302 are amplified by amplifiers 407 and 408 and differentially input to a differential amplifier 403 as shown in FIG. From the output of the differential amplifier 403, the optical disc 100 and the lens holder 10
The inclination with 1 is calculated.

[0005] As shown in FIG. 24, from the inclination angle and the deviation between the optical axis of the objective lens and the optical axis of the collimator, an optimal lens inclination is obtained by a preset unit 404 preferably set in a ROM (read only memory). A phase compensation circuit 40 for applying a servo based on the calculation results of both
5 and the drive amplifier 406, the tilt correction coil 10
5 is driven.

The lens holder 101 is provided with two slits 102 for passing a yoke member 109 on its plane.
At the center, an objective lens 103 is mounted, and two rectangular flat coils 104 for tracking drive are provided on a pair of opposing side surfaces, for a total of four. Also, a pair of rectangular flat coils are provided on opposite sides in the radial direction (R) of the optical disk as coils 105 for performing tilt correction, and copper foil portions 115 and 116 are provided above and below the coil 105 for performing tilt correction. A printed circuit board (not shown), which is supported and supported, is attached.

The actuator base 108 is provided with yoke portions 109 and 110 projecting therefrom.
A substantially closed magnetic path for driving in the focus direction and the tracking direction is formed via the reference numeral 12. Further, on both side surfaces of the actuator base 108, side yokes 11 for driving the lens holder tilt adjustment having a U-shape in plan view are provided.
3, 114 are provided. And the side yoke 1
13 and 114 are long magnets 106 having opposite poles corresponding to the upper and lower sides of the coil 105 for performing the inclination correction.
And 107 are provided.

The actuator base 108 includes:
Square printed boards 117 and 118 are similarly attached via copper foil portions 119 and 120. Then, the spring wire 121 of phosphor bronze is connected to the spring wire 1.
21 are fixed to the printed circuit boards arranged at both ends and relayed by four, and elastically support the lens holder 101 (see the plan view of FIG. 23 for fixing the spring wire 121).

In FIG. 21, F indicates the focus axis of the moving system of the objective lens actuator, R indicates the tracking axis, and T indicates the tangential axis of the optical disk.

Referring to FIG. 22, the tilt driving of the lens holder 101 according to the prior art will be described. The coils 105 provided on both sides of the lens holder 101 in the radial direction of the optical disk for correcting the left and right tilts are described. When the current directions are the same and the magnetic field directions of the left and right magnets 106 and 107 provided corresponding to the upper and lower sides of the coil 105 for which the inclination is corrected are symmetrical, the electromagnetic drive of both coils is performed by Fleming. The left and right directions of the electromagnetic driving force differ according to the left-hand rule (see arrows F and F ′ in the figure). Accordingly, the center of gravity or the support center of the lens holder 101 is
Although they are almost the same point, they can be rotated around this point, and the inclination of the optical disc 100 can be corrected.

[0011]

However, in this prior art, in order to correct the tilt of the objective lens, a coil 105 for newly correcting tilt is provided separately from a coil for tracking servo and focus servo and a magnet.
In addition, since the magnets 106 and 107 must be provided, the cost is increased. In addition, this prior art includes a coil 105 and a magnet 1 that perform tilt correction on a radial side surface of an optical disc 100 of a lens holder 101 that holds an objective lens 103.
Since the lenses 06 and 107 must be arranged, there is a problem that the lateral width and the weight of the objective lens driving device increase.

The present invention has been made for the purpose of solving such problems of the prior art.

[0013]

Means for solving the above problems will be described below with reference to FIG. 1 corresponding to an embodiment.
explain. According to the present invention, one magnetic circuit including at least one multipole magnetized magnet 5 is formed, and a focus coil 3f, a tracking coil 3tr, and a tilt coil 3ti are provided in a magnetic gap 5g of the magnetic circuit. Is provided with the coil unit 3 mounted thereon.

In the above-described configuration, the magnet 5 magnetized to have multiple poles also performs tilt correction, so that a dedicated magnet for tilt correction is not required.

[0015]

FIG. 1 is a perspective view showing an embodiment of the present invention. In FIG. 1, 1 is a lens holder, 2 is an objective lens, 3 is a coil unit, 3f is a focus coil, 3tr is a tracking coil, 3ti is a tilt coil, 5 is a magnet, and 5g is a magnetic gap.

The lens holder 1 is made of a light metal having a high flexural modulus, for example, a magnesium alloy, or a resin made of carbon fiber. Through the use of such materials,
The bending elastic modulus of the lens holder 1 itself increases, and the higher-order resonance frequency increases. Thereby, it is possible to cope with an increase in the speed of the optical disk device.

The lens holder 1 has a tracking direction T
Are formed with two notches 1a. The thickness of the objective lens mounting portion 1b for holding the objective lens 2 is uniform.

The notch 1a has an insulating protective film (not shown) for reinforcement formed on the surface thereof. This is because light metal having a high flexural modulus, such as a magnesium alloy, or a resin made of carbon fiber used for the lens holder 1 has a high conductivity, so that the insulating property of the coil unit 3 attached to the notch 1a is high. This is to ensure. When the insulating protective film for reinforcement is not formed on the surface of the cutout portion 1a of the lens holder 1, the insulating protective film for reinforcement (not shown) is provided on the coil unit 3 attached to the cutout portion 1a. Z)
Is formed to ensure the insulation of the coil unit 3.

The coil unit 3 has a required number of printed boards 31 on which one focus coil 3f and four tracking coils 3tr are formed, and a plurality of printed boards 32 on which two tilt coils 3ti are formed. It is formed. One focus coil 3f is arranged at the center of the printed circuit board 31, and four tracking coils 3tr are separated from the center of gravity of the movable part including the lens holder 1 holding the objective lens 2 in the optical axis direction of the objective lens. Are arranged in the left and right directions (tracking direction T), that is, in two stages up and down on the left and right of one focus coil 3f.
The four tracking coils 3tr are connected in series. Note that the tracking coil 3tr may be composed of two pieces. The two tilt coils 3ti are arranged on the left and right (tracking direction T) from the center of the printed circuit board 32. The two tilt coils 3ti are connected in series.

The printed board 31 and the printed board 32 are stacked symmetrically with respect to the tracking direction T. For example, both sides of the two printed boards 32 are printed on the printed board 31.
It is performed so as to be sandwiched between. By doing so, the driving points in each direction coincide with each other, and resonance (pitching resonance, yawing resonance) due to the mismatching of the driving points can be avoided.

The above is the case where one focus coil 3f and four tracking coils 3tr are formed on the printed circuit board 31. Four cas coils 3f and four tracking coils are individually formed on two printed circuit boards. A coil 3tr may be formed. Also in this case, the printed circuit boards are stacked symmetrically as viewed from the tracking direction T.

The coil unit 3 is fixed to the lens holder 1 by being inserted into and bonded to the notch 1a. Six V grooves 3v are formed at both ends in the tracking direction T of the coil unit 3, and one ends of the six conductive elastic members 4 are fixed to the V grooves 3v by solder (not shown). The conductive elastic body 4 which is a lead wire is used for driving the focus coil.
There are a total of six coils, two for driving the tracking coil and two for driving the tilt coil. Coil unit 3
Are supported by six conductive elastic bodies. In order to elastically support the lens holder 1 which is a movable part,
Although four conductive elastic members 4 are sufficient, the use of the conductive elastic members 4 for driving the tilt coil allows the use of flexible conductors, the installation of supports, and the contact with other members accompanying the driving. Danger and the like can be avoided.

The magnet 5 is magnetized to two poles in the focus direction F by a boundary line 5b between the N pole and the S pole, and is bonded to the yoke 7 on the yoke base 6. As shown in FIG. 2, the boundary line 5b between the N pole and the S pole is located at the center of the magnet 5 in the focus direction F, and the two magnets 5 oppose each other to form a magnetic gap 5g. In the focus direction F, the direction of the magnetic force line B is reversed.

In this case, the width W of the magnet 5 is as shown in FIG. 3 at the movable neutral position of the movable portion movably supported by the conductive elastic body 4 in a cantilever manner, that is, at its own weight position in the focus direction F. As shown, when the coil unit 3 is arranged in the magnetic gap 5g, the vertical sides A on the left and right inner sides of the vertical sides parallel to the focus direction F of the four tracking coils 3tr arranged vertically in two stages on the left and right. C, as shown in FIG.
Out of the vertical sides parallel to the focus direction F of the tilt coils 3ti, the vertical sides a ′ and c ′ on the left and right sides are arranged in the magnetic gap 5g (indicating a gap within the width W of the opposed magnet 5). It is defined as follows. Also, as shown in FIG. 3, the height H of the magnet 5 is set to one focus coil 3f disposed at the center of the printed circuit board 31.
As shown in FIG. 4, the horizontal sides b and d perpendicular to the focus direction F and the horizontal sides B and D at the top and bottom of the horizontal sides perpendicular to the focus direction F of the tracking coil 3tr are tilt coils 3ti as shown in FIG. The horizontal sides b ′ and d ′ perpendicular to the focus direction F are determined so as to be arranged within the magnetic gap 5g (indicating a gap within the height H of the opposed magnet 5).

Boundary line 5b between N pole and S pole of magnet 5
As shown in FIG. 3, a horizontal side B perpendicular to the focus direction F of the upper tracking coil 3tr is provided at the center of the lower side b and the upper side d perpendicular to the focus direction F of the focus coil 3f. A lower side B of D and a horizontal side B perpendicular to the focus direction F of the lower tracking coil 3tr;
At the center of the upper side D of D and as shown in FIG. 4, a horizontal side b ′ perpendicular to the focus direction F of the tilt coil 3ti,
It is located at the center between the lower side b 'and the upper side d' of d '. The center of the magnet 5 substantially matches the center of the coil unit 3.

The coil unit 3 is disposed in the magnetic gap 5g, and the other end of the conductive elastic body 4 is fixed to the base substrate 9 through the wire base 8 by soldering. Thereby, the focus coil 3 f, the tracking coil 3 tr, and the tilt coil 3
ti is arranged in the magnetic gap 5g,
The movable part including the lens holder 1 holding the objective lens 2 can be moved with respect to a fixed part composed of the magnet 5, the yoke base 6, the yoke 7, the wire base 8, and the base substrate 9. We support in cantilever type.

In FIG. 3, the tracking coil 3tr
When current flows through the four tracking coils 3tr in the tracking direction T based on Fleming's left-hand rule, currents (shown by arrows) flowing in the vertical sides A and C parallel to the focus direction F of the tracking coil 3tr. When a driving force in the same direction is generated, and a current flows through the focus coil 3f, a current (shown by an arrow) flowing in horizontal sides b and d perpendicular to the focus direction F of the focus coil 3f causes Fleming's left-hand rule. Accordingly, a driving force is generated in the focus coil 3f in the focus direction F.

Further, in FIG. 4, the tilt coil 3t
When a current is passed through i, the current (shown by arrows) flowing in horizontal sides b ′ and d ′ perpendicular to the focus direction F of the tilt coil 3ti focuses on the two tilt coils 3ti based on Fleming's left-hand rule. Driving forces F ′ which are opposite to each other in the direction F are generated. The reverse driving force F ′ generates a moment around the center of gravity of the movable part, and adjusts the tilt of the lens holder 1 and thus the objective lens 2.

As described above, one magnetic circuit including at least one magnet 5 is formed, and if only the focus coil 3f and the tracking coil 3tr are provided in the same magnetic gap 5g in the magnetic gap 5g of the magnetic circuit. When the tilt coil 3ti is provided, not only focus servo and tracking servo but also tilt servo (adjustment of the tilt of the objective lens 2) can be performed. Therefore, a magnet for adjusting the inclination of the objective lens 2 is unnecessary. Therefore, the number of parts is small, the inclination of the objective lens 2 can be adjusted at low cost, and the size of the entire objective lens driving device can be reduced.

In the above, one focus coil 3f and four tracking coils 3tr,
In the case where two tilt coils 3ti are formed on the printed circuit board 32, four tracking coils 3tr are formed on the printed circuit board 31 and one focus coil 3f and two tilt coils 3ti are formed on the printed circuit board 32. It may be formed. The two tilt coils 3ti are arranged on the left and right (tracking direction T) from the center of the printed circuit board 32. The two tilt coils 3ti are connected in series. One focus coil 3f is arranged outside the two tilt coils 3ti. The four tracking coils 3tr are arranged vertically in two stages on the left and right sides of the center of gravity of the movable portion including the lens holder 1 holding the objective lens 2 in the optical axis direction of the objective lens. The four tracking coils 3tr are connected in series.
Note that the tracking coil 3tr may be composed of two pieces.

In this case, the width W of the magnet 5 is as shown in FIG. 5 at the movable neutral position of the movable portion movably supported by the conductive elastic body 4 in a cantilever manner, that is, at its own weight position in the focus direction F. As shown, when the coil unit 3 is arranged in the magnetic gap 5g, the vertical sides A on the left and right inner sides of the vertical sides parallel to the focus direction F of the four tracking coils 3tr arranged vertically in two stages on the left and right. As shown in FIG. 6, the vertical sides a and c parallel to the focus direction F of one focus coil 3f are arranged in the magnetic gap 5g (indicating a gap within the width W of the opposed magnet 5) as shown in FIG. It is defined to be.

As shown in FIG. 5, the height H of the magnet 5 is such that the upper and lower outer horizontal sides B and D of the horizontal side perpendicular to the focus direction F of the tracking coil 3tr are:
As shown in FIG. 6, the horizontal sides b and d perpendicular to the focus direction F of the focus coil 3f are arranged in the magnetic gap 5g (indicating a gap within the height H of the facing magnet 5). Stipulated.

Boundary line 5b between N pole and S pole of magnet 5
Is, as shown in FIG. 5, an upper tracking coil 3t.
As shown in FIG. 6, the lower side B of the horizontal sides B and D perpendicular to the focus direction F of r, and the center of the upper side D of the horizontal sides B and D perpendicular to the focus direction F of the lower tracking coil 3tr, and as shown in FIG. At the center of the lower side b and upper side d of the horizontal sides b and d perpendicular to the focus direction F of the coil 3f, a horizontal side b 'perpendicular to the focus direction F of the tilt coil 3ti,
It is located at the center between the lower side b 'and the upper side d' of d '. The center of the magnet 5 substantially matches the center of the coil unit 3.

As described above, the two tilt coils 3ti are moved from the center of the printed circuit board 32 to the left and right (in the tracking direction T).
However, the same effect can be obtained by arranging the two tilt coils 3 ti vertically (focus direction F) from the center of the printed circuit board 32 as shown in FIG.

In this case, as shown in FIG. 8, the coil unit 3 includes a printed board (not shown) on which one tracking coil 3tr and four focus coils 3f are formed, and as shown in FIG. 2 tilt coils 3t
a required number of printed circuit boards (not shown) on which i is formed,
It is formed by being laminated. One tracking coil 3tr is arranged at the center of the printed circuit board 31, and four focus coils 3f are separated from the center of gravity of the movable part including the lens holder 1 holding the objective lens 2 in the optical axis direction of the objective lens. Are arranged in two stages, that is, left and right, that is, left and right of one tracking coil 3tr. The four focus coils 3f are connected in series. Note that the focus coil 3f may be composed of two pieces.
The two tilt coils 3ti are connected in series.

The above is the case where one tracking coil 3tr and four focus coils 3f are formed on a printed circuit board. One tracking coil 3tr and four focus coils are individually formed on two printed circuit boards. 3
f may be formed. Also in this case, the printed circuit board
The layers are symmetrically stacked when viewed from the tracking direction T.

In this case, as shown in FIG. 9, the magnet 5 is magnetized to two poles in the tracking direction T by a boundary line 5b between the N pole and the S pole, and is bonded to the yoke 7 on the yoke base 6. ing. The boundary line 5b between the north pole and the south pole is located at the center of the magnet 5 in the tracking direction T, and the two magnets 5 oppose each other to form a magnetic gap 5g. Direction is reversed.

In this case, the width W of the magnet 5 is set at the movable neutral position of the movable portion movably supported by the conductive elastic body 4 in a cantilever manner, that is, at its own weight position in the focus direction F as shown in FIG. As shown, when the coil unit 3 is disposed in the magnetic gap 5g, of the vertical sides parallel to the focus direction F of the four focus coils 3f arranged vertically in two stages on the left and right, the left and right outer vertical sides a, c
However, as shown in FIG. 7, the vertical sides a ′ and c ′ parallel to the focus direction F of the two tilt coils 3ti arranged in the upper and lower stages are within the magnetic gap 5g (the width W of the opposing magnet 5). (Referred to as a gap within). The height H of the magnet 5 is, as shown in FIG.
As shown in FIG. 7, the horizontal sides b and d of the upper and lower inner sides and the horizontal sides B and D perpendicular to the focus direction F of the tracking coil 3tr among the horizontal sides perpendicular to the tilt coil 3 as shown in FIG.
Of the horizontal sides perpendicular to the focus direction F of ti, the upper and lower outer horizontal sides b ′ and d ′ are arranged in the magnetic gap 5g (indicating a gap within the height H of the opposed magnet 5). Stipulated.

Boundary line 5b between N pole and S pole of magnet 5
As shown in FIG. 8, the left side c of the vertical sides a and c parallel to the focus direction F of the right focus coil 3f and the right side a of the vertical sides a and c parallel to the focus direction F of the left focus coil 3f. At the center of the tracking coil 3t
r at the center of the right side A and the left side C of the vertical sides A and C parallel to the focus direction F, and as shown in FIG. 7, the right sides of the vertical sides a 'and c' parallel to the focus direction F of the tilt coil 3ti. It is located at the center of a 'and the left side c'. The center of the magnet 5 substantially matches the center of the coil unit 3.

In FIG. 8, the tracking coil 3tr
, A driving force is applied to the tracking coil 3tr in the tracking direction T based on Fleming's left-hand rule by currents (illustrated by arrows) flowing in the vertical sides A and C parallel to the focus direction F of the tracking coil 3tr. When a current is caused to flow through the focus coil 3f, currents (illustrated by arrows) flowing in horizontal sides b and d perpendicular to the focus direction F of the focus coil 3f cause four focuses based on Fleming's left-hand rule. Coil 3f
, A driving force in the same direction as the focus direction F is generated.

In FIG. 7, when a current is passed through the tilt coil 3ti, a current (shown by an arrow) flowing through the vertical sides a 'and c' parallel to the focus direction F of the tilt coil 3ti is based on Fleming's left-hand rule. In the two tilt coils 3ti, driving forces F 'opposite to each other in the tracking direction T are generated. By this reverse driving force F ',
A moment is generated around the center of gravity of the movable part, and the tilt of the lens holder 1 and thus the objective lens 2 is adjusted.

In the above, one tracking coil 3tr and four focus coils 3f,
In the case where two tilt coils 3ti are formed on the printed board 32, one tracking coil 3tr is formed on the printed board 31, and four focus coils 3f and two tilt coils 3ti are formed on the printed board 32. It may be formed.

In this case, as shown in FIG. 10, the coil unit 3 includes a printed circuit board (not shown) on which one tracking coil 3tr is formed, and two tilt coils 3ti as shown in FIG. A required number and a printed circuit board (not shown) on which four focus coils 3f are formed are stacked and formed. One tracking coil 3tr is arranged at the center of the printed circuit board 31,
The four focus coils 3f are arranged vertically on the left and right sides of the center of gravity of the movable part including the lens holder 1 holding the objective lens 2 in the direction of the optical axis of the objective lens, that is, on the left and right of the two tilt coils 3ti. They are arranged in columns. The four focus coils 3f are connected in series. Note that the focus coil 3f may be composed of two pieces.
The two tilt coils 3ti are connected in series.

In this case, the width W of the magnet 5 is as shown in FIG. 11 at the movable neutral position of the movable portion movably supported by the conductive elastic body 4 in a cantilever manner, that is, at its own weight position in the focus direction F. As shown, when the coil unit 3 is arranged in the magnetic gap 5g,
Out of the vertical sides parallel to the focus direction F of the four focus coils 3f arranged in a row, the right and left outer vertical sides a,
c is the tracking coil 3tr as shown in FIG.
The vertical sides A and C parallel to the focus direction F are defined so as to be arranged within the magnetic gap 5g (indicating a gap within the width W of the opposed magnet 5). As shown in FIG. 11, the height H of the magnet 5 is such that the upper and lower inner horizontal sides b and d of the horizontal sides perpendicular to the focus direction F of the focus coil 3f and the tilt coil 3t
Among the horizontal sides perpendicular to the focus direction F of i, the horizontal sides b ′ and d ′ on the upper and lower sides are horizontal sides B and D perpendicular to the focus direction F of the tracking coil 3tr as shown in FIG. It is set so as to be arranged within 5 g (indicating a gap within the height H of the facing magnet 5).

Boundary line 5b between N pole and S pole of magnet 5
Is the right focus coil 3f as shown in FIG.
The center of the left side c of the vertical sides a and c parallel to the focus direction F and the right side a of the vertical sides a and c parallel to the focus direction F of the left focus coil 3f is parallel to the focus direction F of the tilt coil 3ti. Right side a 'of vertical side a', c '
And the center of the left side c ′, and as shown in FIG. 10, at the center of the right side A and the left side C of the vertical sides A and C parallel to the focus direction F of the tracking coil 3tr. The center of the magnet 5 substantially matches the center of the coil unit 3.

In the above, the magnet 5 is magnetized with two poles in the focus direction F or the tracking direction T. However, as shown in FIG. 12, the magnet 5 is magnetized with two poles in the tracking direction. Alternatively, ones which are arranged in two stages in the focus direction and magnetized to four poles may be used. In this case, as shown in FIG. 12, the two tracking coils 3tr are
Are arranged in the first quadrant and the second quadrant and in the third quadrant and the fourth quadrant, and when currents in opposite directions are supplied to both coils, the driving force in the same direction in the tracking direction T is applied to the two tracking coils 3tr. Occurs. Further, as shown in FIG. 13, the two focus coils 3f are moved left and right, that is, in the first and fourth quadrants and in the second and third quadrants of the magnet 5,
When the two coils are arranged and a current of opposite direction is applied to both coils, a driving force in the same direction in the focus direction F is generated in the two focus coils 3f. Further, as shown in FIG. 14, two tilt coils 3ti are arranged on the left and right, that is, in the first quadrant and the fourth quadrant and the second quadrant and the third quadrant of the magnet 5, and the same is applied to both coils. When a current of the same direction is supplied, driving forces F ′ that are opposite to each other in the focus direction F are generated in the two tilt coils 3ti. The reverse driving force F ′ generates a moment around the center of gravity of the movable part, and adjusts the tilt of the lens holder 1 and thus the objective lens 2.

Although not shown, the two tilt coils 3ti are not left and right, but the two tilt coils 3ti are up and down, that is, the first and second quadrants of the magnet 5 and the third and fourth quadrants. And a current in the same direction may flow through both coils. Then, driving forces F ′ that are opposite to each other in the tracking direction T are generated in the two tilt coils 3ti. Due to the driving force F ′ in the opposite direction, a moment is generated around the center of gravity of the movable part, and the lens holder 1,
Consequently, the inclination of the objective lens 2 is adjusted.

When the magnet 5 is magnetized with four poles, the number of coils is reduced from seven to six as compared with magnetized with two poles, so that coils can be saved. Further, in the case of two-pole magnetization, the portion facing the portion that generates the driving force of the coil must be disposed outside the magnetic gap 5g (see 3t in FIGS. 3 and 5).
r side A side, C side, b side, d side of 3f in FIGS.
In the case of pole magnetization, there is no need to arrange the coil outside the magnetic gap 5g, so that the coil arrangement is easy. Further, when the coil is disposed in the magnetic gap 5g, the two sides facing each other always contribute to the generation of the driving force, so that the utilization factor of the coil is improved.

In the above description, the magnet 5 is a two-pole or four-pole magnetized one. As shown in FIG. 15, one pole (for example, S-pole) has an I-shaped front shape and a two-sided quadrilateral. The other poles (for example, N poles) may be inserted into the space of one pole and may be magnetized to three poles as a frontal quadrilateral as a whole. In this case, as shown in FIG.
When the two tracking coils 3tr are arranged on the left and right, that is, on the I-shaped web portion and the N pole, and when currents in opposite directions are applied to both coils, the two tracking coils 3tr have the same direction in the tracking direction T. A driving force is generated. Also, as shown in FIG. 15, four focus coils 3f are arranged on the left and right and up and down, that is, on the upper and lower sides and the N pole of the I-shaped flange portion, and the two upper coils have the same orientation, and the lower two have the opposite upper side. of,
When currents in the same direction flow, four focus coils 3f
, A driving force in the same direction as the focus direction F is generated. Also, as shown in FIG. 16, four tilt coils 3ti
To the left and right and up and down, that is,
When they are arranged at the poles and currents in opposite directions are applied to two upper stages and opposite to upper stages in two lower stages, the left and right tilt coils 3ti are formed.
, Driving forces F ′ are generated in opposite directions in the focusing direction F. The reverse driving force F ′ generates a moment around the center of gravity of the movable part, and adjusts the tilt of the lens holder 1 and thus the objective lens 2.

When the magnet 5 is formed by three-pole magnetization,
As shown in FIG. 17, one pole (for example, S pole) is
And two other poles (for example, N pole) in frontal quadrilateral
May be inserted into a single pole space to form a frontal quadrilateral as a whole. In this case, as shown in FIG. 17, four tracking coils 3tr are arranged in the left and right and up and down, that is, on the left and right and the N pole of the H-shaped flange portion, and the upper two are opposed to the upper two. When currents in the same direction and opposite directions are supplied, a driving force in the same direction in the tracking direction T is generated in the four tracking coils 3tr. Also, as shown in FIG. 17, two focus coils 3f are arranged up and down, that is, on the H-shaped web portion and the N pole, and when currents in opposite directions are applied to both coils, two focus coils 3f are formed. A driving force in the same direction in the focus direction F is generated at 3f. Also, as shown in FIG. 18, the four tilt coils 3ti are arranged on the left and right and up and down, that is, on the left and right and the N pole of the H-shaped flange portion, and are oppositely directed to the upper two and the lower two are opposite to the upper. When a current in the opposite direction is supplied, driving forces F ′ in opposite directions in the tracking direction T are generated in the upper and lower tilt coils 3ti. The reverse driving force F ′ generates a moment around the center of gravity of the movable part, and adjusts the tilt of the lens holder 1 and thus the objective lens 2.

The above description has four tilt coils 3ti,
Although the number of focus coils 3f and tracking coils 3tr is two or four, the tilt coil 3t
When i is two, as shown in FIG. 19, one pole (for example, S pole) has a front shape T-shape, and a front quadrilateral 2
The other poles (for example, N poles) are inserted into the space of one pole, and a pole which is magnetized to three poles as a frontal quadrilateral as a whole is used. In this case, two tracking coils 3tr
Are located at the center, that is, at the T-shaped vertical portion and the N pole, two focus coils 3f and two tilt coils 3ti.
Are arranged on the left and right parts, that is, on the T-shaped horizontal part and the N pole.

As shown in FIG. 20, one pole (for example, S pole) has a U-shaped front shape, and one other pole (for example, N pole) of a front quadrilateral is inserted into the space of one pole. As a whole, a front side quadrilateral magnetized to two poles is used. In this case, one focus coil 3f is provided at a central portion, that is, at a U-shaped horizontal portion and an N pole, at two tracking coils 3tr, at two tilt coils 3ti, at right and left portions, that is, at a U-shaped vertical portion. And the N pole.

In the case of three-pole magnetization, as in the case of four-pole magnetization, the coil arrangement becomes easier and the coil utilization rate is improved, as compared with the case of four-pole magnetization.

Even in the case of two-pole magnetization, three-pole magnetization, and four-pole magnetization using a U-shape, the coil unit has a focus coil 3f and a tracking coil 3tr similarly to the two-pole magnetization.
In addition, a plurality of printed circuit boards on which the tilt coils 3ti are individually mounted are stacked and formed. In addition, a plurality of printed circuit boards on which the focus coil 3f and the tracking coil 3tr are mounted and a plurality of printed circuit boards on which the tilt coil 3ti is mounted may be formed by lamination. Further, the focus coil 3f and the tilt coil 3ti may be formed.
PCB with tracking coil and 3tr
May be formed by laminating a plurality of printed circuit boards on which is mounted.

In the above description, the magnetic gap 5g is formed on the yoke base 6 as shown in FIGS. 1, 2, and 9 including the case of 2-pole magnetization, 3-pole magnetization, and 4-pole magnetization using a U-shape. Although it is formed by the opposition of two magnets 5 adhered to the yoke 7, the magnet 5 may be constituted by one magnet and formed by the opposition of the magnet 5 and the yoke 7. Further, the opposing yoke 7 may be omitted, and the space from the N pole to the S pole may be used as the magnetic gap 5g.

[0056]

As described above, the present invention provides:
One magnetic circuit including at least one magnet is formed, and a coil unit in which a focus coil, a tracking coil, and a tilt coil are mounted is arranged in a magnetic gap of the magnetic circuit. Therefore, the tilt of the objective lens can be adjusted by the focus / tracking drive magnet, and a magnet for adjusting the tilt of the objective lens is unnecessary. Therefore, according to the present invention, it is possible to avoid an increase in cost and an increase in size due to the adjustment of the tilt of the objective lens.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a side view showing a magnetic circuit in which a magnet according to one embodiment of the present invention is magnetized to two poles in a focus direction.

FIG. 3 is a layout diagram showing a positional relationship between a magnet magnetized to two poles in a focus direction and a focus coil / tracking coil at a position of its own weight in the focus direction according to an embodiment of the present invention;

FIG. 4 is a layout diagram showing a positional relationship between a magnet and a tilt coil magnetized in two poles in the focus direction at a position of its own weight in the focus direction according to the embodiment of the present invention;

FIG. 5 is a layout diagram showing a positional relationship between a magnet magnetized in two poles in the focus direction and a tracking coil at a position of its own weight in the focus direction in another embodiment of the present invention.

FIG. 6 is a layout diagram showing a positional relationship between a magnet magnetized to two poles in a focus direction and a focus coil / tilt coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 7 is a layout diagram showing a positional relationship between a magnet and a tilt coil magnetized in two poles in a tracking direction at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 8 is a layout diagram showing a positional relationship between a magnet magnetized in two poles in a tracking direction and a focus coil / tracking coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 9 is a plan view showing a magnetic circuit in which a magnet according to another embodiment of the present invention is magnetized to two poles in a tracking direction.

FIG. 10 is a layout diagram showing a positional relationship between a magnet magnetized to two poles and a tracking coil in a tracking direction at a self-weight position in a focus direction in another embodiment of the present invention.

FIG. 11 is a layout diagram showing a positional relationship between a magnet magnetized to two poles in a tracking direction and a focus coil and a tilt coil in a self-weight position in a focus direction in another embodiment of the present invention.

FIG. 12 is a layout view showing a positional relationship between a magnet magnetized to four poles and a tracking coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 13 is a layout diagram showing a positional relationship between a magnet magnetized to four poles and a focus coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 14 is a layout diagram showing a positional relationship between a magnet magnetized to four poles and a tilt coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 15 is a layout diagram showing a positional relationship between a magnet magnetized to three poles and a focus coil / tracking coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 16 is a layout diagram showing a positional relationship between a three-pole magnetized magnet and a tilt coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 17 is a layout diagram showing a positional relationship between a magnet magnetized to three poles and a focus coil / tracking coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 18 is a layout diagram showing a positional relationship between a three-pole magnetized magnet and a tilt coil at a position of its own weight in the focus direction in another embodiment of the present invention.

FIG. 19 is a layout view showing a positional relationship among a magnet magnetized to three poles and a focus coil / tracking coil / tilt coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 20 is a layout diagram showing a positional relationship among a magnet magnetized to two poles and a focus coil / tracking coil / tilt coil at a position of its own weight in a focus direction in another embodiment of the present invention.

FIG. 21 is an exploded perspective view of a conventional technique.

FIG. 22 is an explanatory diagram of a tilt correction drive according to the related art.

FIG. 23 is a plan view of a conventional actuator.

FIG. 24 is a block diagram illustrating a configuration of a circuit that performs tilt driving in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens holder 2 Objective lens 3 Coil unit 3f Focus coil 3tr Tracking coil 3ti Tilt coil 5 Magnet 5g Magnetic gap

Claims (15)

[Claims] At least one magnetic circuit including at least one multi-pole magnetized magnet is formed, and a focus coil, a tracking coil, and a tilt coil are mounted in a magnetic gap of the magnetic circuit. Object pickup lens driving device for optical pickup with coil unit 2. The objective lens driving device for an optical pickup according to claim 1, wherein the magnet is magnetized to two poles. 3. The objective lens driving device for an optical pickup according to claim 1, wherein the magnet is magnetized to four poles. 4. The objective lens driving device for an optical pickup according to claim 1, wherein the magnet is magnetized to three poles. 5. One focus coil, an even number of tracking coils, and two tilt coils.
2. The objective lens driving device for an optical pickup according to claim 1, wherein the magnet is magnetized with two poles in the focus direction. 6. An even number of focus coils, one tracking coil, and two tilt coils,
2. The objective lens driving device for an optical pickup according to claim 1, wherein the magnet is magnetized to two poles in the tracking direction. 7. Two focus coils, two tracking coils, two tilt coils, and two magnets magnetized in the tracking direction are arranged in two stages in the focus direction. 2. The objective lens driving device for an optical pickup according to claim 1, wherein the objective lens is polarized. 8. Four focus coils, two tracking coils, and four tilt coils, and one pole of the magnet has a front shape I-shape, and two other poles of the front quadrilateral have one pole. 2. The objective lens driving device for an optical pickup according to claim 1, wherein said device is inserted into said space and magnetized to three poles as a frontal quadrilateral as a whole. 9. A motor comprising two focus coils, four tracking coils and four tilt coils, one magnet having a front shape of H-shape, and two other poles of the front shape quadrilateral having one pole. 2. The objective lens driving device for an optical pickup according to claim 1, wherein said device is inserted into said space and magnetized to three poles as a frontal quadrilateral as a whole. 10. There are two focus coils, two tracking coils, and four tilt coils.
2. The light according to claim 1, wherein the magnet is magnetized into three poles as a frontal quadrilateral as a whole by inserting one pole in a frontal T-shape and inserting two other poles of the frontal quadrilateral into a space of one pole. Objective lens drive for pickup 11. There are two focus coils, two tracking coils, and four tilt coils,
2. The light according to claim 1, wherein the magnet is magnetized to two poles as a front quadrilateral as a whole by inserting one pole into a front U shape and inserting one other pole of the front quadrilateral into the space of one pole. Objective lens drive for pickup 12. The optical pickup according to claim 1, wherein the coil unit is formed by stacking a plurality of printed circuit boards on each of which a focus coil, a tracking coil, and a tilt coil are individually mounted. Objective lens drive 13. The coil unit according to claim 1, wherein a plurality of printed circuit boards on which a focus coil and a tracking coil are mounted and a plurality of printed circuit boards on which a tilt coil is mounted are stacked. Objective lens driving device for optical pickup as described above 14. The coil unit according to claim 1, wherein a plurality of printed circuit boards on which a focus coil and a tilt coil are mounted and a plurality of printed circuit boards on which a tracking coil is mounted are stacked. Objective lens driving device for optical pickup as described above 15. The coil unit according to claim 1, wherein the coil unit is fixed to the lens holder and supported by six conductive elastic members having one end fixed to the coil unit. Objective lens driving device for optical pickup as described above