JP2001101687A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup capable of preventing (or suppressing) the inclination of the optical axis of an objective lens from a reference axis. SOLUTION: This optical pickup 1 is provided with a pickup base 2, an actuator base 3, a damper base 4, and an actuator 5 consisting of fixed and movable parts 5a and 5b. The fixed part 5a is provided with a pair of yokes 51, and a pair of permanent magnets 52 joined to the yokes. The movable part 5b is provided with an objective lens 54, a lens holder 53 for supporting the objective lens 54, and four tracking coils 55 and focusing coils 56 disposed in the lens holder 53, and supported on the damper base 4 by four suspension wires 7 so as to be displaced. The shape of the permanent magnet 52 is set in such a way as to substantially cancel the moment of force around a straight line 61 among electromagnetic forces applied to the tracking coils 55 and/or the focusing coils 56.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical pickup.

[0002]

2. Description of the Related Art An optical pickup is mounted on various optical disk devices mounted on a personal computer or the like.

The optical pickup has a lens holder, a damper base for supporting the lens holder movably via four suspension wires, and a yoke provided with a permanent magnet (magnet). .

[0004] The lens holder supports an objective lens, and is provided with a tracking coil and a focusing coil.

FIG. 7 is a side view showing a permanent magnet and a yoke of a conventional optical pickup, and FIG. 8 is a plan view showing a permanent magnet and a yoke of the conventional optical pickup.

The magnetic field (magnetic flux) distribution when the permanent magnet 110 is installed at one end of the U-shaped yoke 120 is as shown in FIG. 7 and FIG. That is, the yoke 12
The magnetic flux density inside 0 is the highest at the center of the permanent magnet 110 and becomes lower as the distance from the center increases.

FIG. 9 is a front view schematically showing a lens holder and a permanent magnet of a conventional optical pickup.

For convenience of explanation, it is assumed that an X axis, a Y axis, and a Z axis (XYZ coordinate system) are orthogonal to each other as shown in FIG. That is, the direction of the X axis is the radial direction (tracking direction: radial direction) of the optical disk (not shown) mounted, the direction of the Y axis is the longitudinal direction (tangential direction) of the suspension wire, and the direction of the Z axis is the direction of the reference axis ( Focusing direction).

As shown in FIG. 9, when a current i1 flows through the pair of tracking coils 140 and a current i2 flows through the focusing coil 150, the electromagnetic force F1 is applied to the tracking coil 140 on the left side in FIG. The electromagnetic force F2 acts on the tracking coil 140 and the electromagnetic force F7 acts on the focusing coil 150, whereby the lens holder 130 moves to the lower right in FIG. The amount of movement of the lens holder 130 to the right in FIG. 9 is defined as L1.

In this case, the electromagnetic force F7 is applied to the lens holder 1
9, the lens holder 130 is rotated about the center of gravity G in the counterclockwise direction in FIG. 9 by the electromagnetic force F7. I do. The center of gravity G
A force (rotational force) for rotating counterclockwise in FIG.

On the other hand, the tracking coil 1 on the left side in FIG.
Electromagnetic forces F3 and F4 act on 40 in addition to the electromagnetic force F1, and electromagnetic forces F5 and F6 act on the tracking coil 140 on the right side in FIG. 9 in addition to the electromagnetic force F2. As described above, the magnetic flux density inside the yoke 120 decreases as the distance from the center of the permanent magnet 110 decreases, so that F3> F4,
F5> F6. Due to these electromagnetic forces F3 to F6, the lens holder 130 tends to rotate clockwise in FIG. The force (rotational force) for rotating the lens holder 130 clockwise in FIG. 9 about the center of gravity G is F8.

Therefore, when the force F8 is larger than the force F9, the lens holder 130 is rotated around the center of gravity G by a predetermined amount in the clockwise direction in FIG.
The zero optical axis 170 is inclined at a predetermined angle in the clockwise direction in FIG. 9 with respect to the reference axis.

Conversely, when the force F9 is larger than the force F8, the lens holder 130 rotates a predetermined amount around the center of gravity G in the counterclockwise direction in FIG.
The 0 optical axis 170 is inclined at a predetermined angle counterclockwise in FIG. 9 with respect to the reference axis.

FIG. 10 shows a reference axis (Z) when the lens holder 130 is moved in a conventional optical pickup.
Of the optical axis 170 of the objective lens 160 (X-
FIG. 7 is a diagram (an example) illustrating an inclination angle β) on a Z plane.

The position of the optical axis 170 in FIG. 10 is the position of the objective lens 160 (lens holder 130). When the lens holder 130 is not moved, the objective lens 1
It is assumed that 60 is located at the origin of the XZ coordinates in FIG.

When the lens holder 130 moves in an arbitrary direction, the optical axis 170 of the objective lens 160 is inclined with respect to the reference axis 180 as shown in FIG. That is, in the conventional optical pickup, the posture of the objective lens 160 (the lens holder 130) is unstable.

If the inclination angle β of the optical axis 170 is relatively large, recording and reproduction may not be performed, particularly on a high-density recording optical disk such as a DVD (digital video disk).

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical pickup capable of preventing (or suppressing) the optical axis of an objective lens from being inclined from a reference axis.

[0019]

This and other objects are achieved by the present invention which is defined below as (1) to (10).

(1) A tracking coil, a focusing coil, an objective lens, a lens holder supporting the tracking coil, the focusing coil and the objective lens, and the lens holder being displaceable via a plurality of suspension wires. An optical pickup having a damper base to be supported, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet installed on the yoke, the optical pickup acting on the tracking coil and / or the focusing coil. An optical pickup characterized in that the shape of the magnet is set such that an electromagnetic force for tilting the optical axis of the objective lens from a reference axis substantially cancels out.

(2) A tracking coil, a focusing coil, an objective lens, a lens holder for supporting the tracking coil, the focusing coil and the objective lens, and the lens holder being displaceable via a plurality of suspension wires. An optical pickup having a damper base to be supported, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet installed on the yoke. The magnet so that the electromagnetic force for tilting the optical axis from the reference axis and the electromagnetic force that acts on the focusing coil and tilts the optical axis of the objective lens from the reference axis substantially cancel each other. Optical pick-up characterized by setting the shape of Up.

(3) A tracking coil, a focusing coil, an objective lens, a lens holder supporting the tracking coil, the focusing coil and the objective lens, and the lens holder being displaceable via a plurality of suspension wires. An optical pickup having a damper base to be supported, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet installed on the yoke, the optical pickup acting on the tracking coil and / or the focusing coil. Wherein the shape of the magnet is set so that the moment of a force around a straight line that is parallel to the suspension wire and passes through the center of gravity of the lens holder, substantially cancels out of the generated electromagnetic force. pick up .

(4) A tracking coil, a focusing coil, an objective lens, a lens holder for supporting the tracking coil, the focusing coil and the objective lens, and the lens holder being displaceable via a plurality of suspension wires. An optical pickup having a damper base to be supported, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet installed on the yoke, among electromagnetic forces acting on the tracking coil.
A moment of force about a straight line parallel to the suspension wire and passing through the center of gravity of the lens holder;
An optical pickup characterized in that the shape of the magnet is set such that, of the electromagnetic force acting on the focusing coil, the moment of the force around the straight line substantially cancels out.

(5) The optical pickup according to any one of (1) to (4), wherein the magnet has a flat plate shape.

(6) The optical pickup according to any one of (1) to (5), wherein a surface of the magnet facing the tracking coil and the focusing coil has a substantially rectangular shape.

(7) In the magnet, a short side of a surface facing the tracking coil and the focusing coil is substantially parallel to the optical axis, and a long side is substantially perpendicular to the suspension wire. The optical pickup according to (6), wherein

(8) The ratio W of the length H in the direction of the optical axis and the length W in the direction perpendicular to the optical axis of the surface of the magnet facing the tracking coil and the focusing coil. The optical pickup according to the above (6) or (7), wherein / H is 1.10 to 1.32.

(9) The above (1) to (8), wherein the maximum inclination angle of the optical axis from the reference axis is 2 mrad or less.
An optical pickup according to any one of the above.

(10) The optical pickup according to any one of the above (1) to (9), wherein the yoke and the magnet are arranged in a pair at both ends of the lens holder via the objective lens. .

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical pickup according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1 is a perspective view showing an embodiment of the optical pickup of the present invention, FIG. 2 is a side view showing a yoke and a permanent magnet of the optical pickup shown in FIG. 1, and FIG. 3 is an optical pickup shown in FIG. FIG. 4 is a front view schematically showing a tracking coil and a focusing coil of the optical pickup shown in FIG. 1, and FIG. 5 is a yoke, a permanent magnet, and a tracking coil of the optical pickup shown in FIG. FIG. 6 is a front view schematically showing a movable portion and a permanent magnet of the actuator of the optical pickup shown in FIG. 1 (a diagram corresponding to FIG. 9).

For convenience of explanation, as shown in FIGS.
An X axis, a Y axis, and a Z axis (XYZ coordinate system) orthogonal to each other are assumed. That is, the direction of the X axis is the radial direction (tracking direction: radial direction) of the optical disk (not shown) mounted, the direction of the Y axis is the longitudinal direction (tangential direction) of the suspension wire, and the direction of the Z axis is the direction of the reference axis ( Focusing direction).

As shown in FIGS. 1 to 5, an optical pickup (optical head) 1 includes a pickup base (optical base) 2, an actuator base 3, a damper base 4, an actuator 5, and four suspension wires. (Suspension spring) 7.

The pickup base 2 has a space (not shown) for accommodating the lower portions of the actuator base 3 and the damper base 4 at a central portion thereof, and an optical disk device (for recording an optical disk) at both ends thereof. Guides 28 and 29 are formed to engage guide rods (not shown) installed on the (and / or regenerating device).

The pickup base 2 is provided with guide portions 28 and 29 which engage with corresponding guide rods, and are reciprocally movable along the guide rods in the radial direction of the optical disk.

In the present invention, an optical disk is a CD,
CD-ROM, CD-R, CD-RW, DVD, DVD
-ROM, DVD-R, DVD-RAM, DVD-RW
In addition to ordinary optical disks (optical disks in a narrow sense), the concept includes a magneto-optical disk.

The actuator base 3 and the damper base 4 are formed integrally. The integrated body of the actuator base 3 and the damper base 4 is supported by the pickup base 2 with its lower part housed in the space of the pickup base 2.

The actuator 5 comprises a fixed part 5a and a movable part 5b. The fixing portion 5a is composed of a pair of yokes 51 and a pair of permanent magnets (magnets) 52 joined thereto, which are fixedly supported by the actuator base 3. This pair of yokes 51
The permanent magnet 52 is disposed at both ends in the Y-axis direction of a lens holder 53 described later via an objective lens 54 described later. Each yoke 51 and the permanent magnet 52
Have the same configuration.

On the other hand, the movable part 5b of the actuator 5
A lens holder 53 having a lens support 531 and five coil supports, an objective lens (condensing lens) 54 supported by the lens support 531 of the lens holder 53,
The lens holder 53 includes four tracking coils 55 and focusing coils 56 wound around corresponding coil supporting portions. Each of the tracking coils 55 has the same configuration.
It is electrically connected.

The lens support portion 531 includes a lens holder 53
Is formed at the center. That is, the objective lens 54
Is located at the center of the lens holder 53.

The coil support around which the focusing coil 56 is wound is formed around the lens holder 53, that is, on the outside.

Further, two coil support portions around which the tracking coil 55 is wound are formed at one end in the Y-axis direction of the lens holder 53 and two at the other end.

The two coil support portions on the one end side are arranged side by side in the X-axis direction. Similarly, the two coil support portions on the other end are also provided side by side in the X-axis direction.

Each of the tracking coil 55 and the focusing coil 56 is wound around the corresponding coil supporting portion in a substantially rectangular shape.

The movable part 5b is attached to the damper base 4,
It is displaceably supported via four suspension wires 7. Each suspension wire 7 also functions as an electric wire (conductor) for energizing the tracking coil 55 and the focusing coil 56.

In this case, the objective lens 54 (movable part 5b)
Is set (adjusted) so that the optical axis 541 of the objective lens 54 is parallel to the reference axis (Z-axis) in a state in which neither the tracking coil 55 nor the focusing coil 56 is energized.

When the tracking coil 55 is energized, an electromagnetic force acts on each tracking coil 55, thereby moving the objective lens 54 (movable part 5b) in the X-axis direction.
That is, it moves in the radial direction (tracking direction: radial direction) of the loaded optical disk.

Further, when the focusing coil 56 is energized, an electromagnetic force acts on the focusing coil 56, and as a result, the objective lens 54 (movable portion 5b)
Axial direction, ie, reference axis direction (focusing direction)
Go to

As will be described later, in the optical pickup 1, even if the objective lens 54 (movable part 5b) moves to an arbitrary position, the reference axis direction and the direction of the optical axis 541 of the objective lens 54 (optical axis direction) ) Substantially coincide (the reference axis and the optical axis 541 of the objective lens 54 are substantially parallel).

Next, the pair of yokes 51 and the permanent magnets 52 of the fixed portion 5a will be described. As described above, these structures are the same, and therefore, typically, one of the yokes 51 (left side in FIG. 1) and Only the permanent magnet 52 will be described.

As shown in FIGS. 1 and 2, the yoke 51
Has a U-shape. The yoke 51 includes two tracking coils 55 and a focusing coil 56.
The two tracking coils 55 and the focusing coil 56 are located inside the yoke 51.

A common permanent magnet 52 corresponding to the two tracking coils 55 and the focusing coil 56 is provided on a surface farther from the objective lens 54 among a pair of opposing surfaces (inner surfaces) of the yoke 51. is set up.

In this case, a gap is provided between the lower surface of the permanent magnet 52 in FIG. 2 and the bottom surface of the yoke 51.

The shape of the permanent magnet 52 acts on the tracking coil 55 and / or the focusing coil 56 so that the optical axis 541 of the objective lens 54 can be used as a reference axis (Z axis).
In particular, the electromagnetic force acting on the tracking coil 55 and / or the focusing coil 56 is parallel to the suspension wire 7 (Y-axis) and substantially equal to the lens so that the electromagnetic force to be inclined from the lens substantially cancels out. A straight line 61 (FIG. 1) passing through the center of gravity G of the holder 53 (movable part 5b)
And FIG. 5) are set such that the moments of force around them substantially cancel out.

In other words, the shape of the permanent magnet 52 acts on the tracking coil 55 and the optical axis 5 of the objective lens 54
41 acts on the focusing coil 56 and an electromagnetic force for tilting the objective lens 41 from the reference axis (Z-axis).
In particular, the suspension wire 7 (Y-axis) of the electromagnetic force acting on the tracking coil 55 is so set that the electromagnetic force for tilting the optical axis 541 of the No. 4 from the reference axis (Z-axis) substantially cancels out. And the lens holder 5
The moment of the force around the straight line 61 passing through the center of gravity G of 3 (the movable part 5b) and the moment of the force around the straight line 61 among the electromagnetic forces acting on the focusing coil 56 are set so as to substantially cancel each other. Is done.

In the present invention, the shape of the permanent magnet (magnet) 52 is a concept including not only a case where a specific shape itself is mentioned but also a case where a dimension is added to the shape.

In this embodiment, the permanent magnet 52 has a flat plate shape. Then, the tracking coil 55 and the focusing coil 56 of the permanent magnet 52 face (oppose).
The shape of the surface 521 to be formed is a rectangle.

As shown in FIG. 1, the permanent magnet 52 and the yoke 51 are connected to the short side 52 of the surface 521 of the permanent magnet 52.
2 are arranged so as to be parallel to the optical axis 541 (Z axis) of the objective lens 54 and the long side 523 (surface 521) is perpendicular to the suspension wire 7 (Y axis).

A laser diode (light emitting portion) (not shown) for emitting a laser beam for irradiating the optical disk is provided at a predetermined position on the lower side of the actuator base 3 of the pickup base 2 in FIG.

Further, on the lower side of the pickup base 2 in FIG.
Engaging claws (engaging projections) 22 and 23 for supporting the substrate and a projection 24 are formed, and the substrate 8 is supported by these engaging claws 22, 23 and the projection 24. A photodiode (light receiving element), not shown, for receiving reflected light from the optical disk is mounted on the substrate 8.

At a position of the pickup base 2 corresponding to the photodiode, one end communicates with the space in which the lower portion of the damper base 4 is housed, and the other end is opened to the bottom surface 21 (not shown). ) Is formed. Light reflected from the optical disk passes through this hole,
The light reaches the light receiving surface of the photodiode.

The actuator 5 of the optical pickup 1
(Particularly, the permanent magnet 52) is preferably set as follows (see FIGS. 1 to 5).

[Permanent Magnet 52] As shown in FIGS. 1 and 3, the length of the short side 522 of the surface 521 of the permanent magnet 52 (the length of the surface 521 in the direction of the optical axis 541) is H, and the long side 523 thereof. (The length of the surface 521 in the direction perpendicular to the optical axis 541) is W, the length H of the short side 522 and the length of the long side 52
The ratio W / H to the length W of 3 is preferably about 1.10 to 1.32.

The distance s between the lower surface of the permanent magnet 52 in FIG. 2 and the bottom surface of the yoke 51 is preferably 0.5 mm or more.

[Tracking Coil 55] Length a in the X-axis direction of the outer portion of tracking coil 55 (see FIG. 4)
Is preferably 2.0 mm or more.

The length b (see FIG. 4) of the inside of the tracking coil 55 in the X-axis direction is preferably 1.0 mm or more.

The length c (see FIG. 4) of the outer portion of the tracking coil 55 in the Z-axis direction is equal to the short side 522 of the permanent magnet 52.
Is preferably smaller by 1 to 2 mm than the length H.

The length d (see FIG. 4) of the inner portion of the tracking coil 55 in the Z-axis direction is the shorter side 522 of the permanent magnet 52.
Is preferably smaller by 2 to 3 mm than the length H.

Distance e between one tracking coil 55 and the other tracking coil 55 (see FIG. 4)
Is preferably 0.5 mm or more.

[Focusing Coil 56] The length f (see FIG. 4) of the focusing coil 56 in the X-axis direction is preferably larger than the length W of the long side 523 of the permanent magnet 52.

The length g (see FIG. 4) of the focusing coil 56 in the Z-axis direction is preferably smaller than the length H of the short side 522 of the permanent magnet 52 by 1 mm or more.

In this optical pickup 1, the reference axis (Z
Angle β of the optical axis 541 of the objective lens 54 from the
10 (see FIG. 10), in particular, the maximum inclination angle βmax in the XZ plane is 2
mrad or less, in particular, 1.5 mrad or less. The optical pickup 1 is mounted on an optical disk device.

Next, the operation of the optical pickup 1 will be described. When a current is applied to each tracking coil 55, an electromagnetic force acts on each tracking coil 55, whereby the objective lens 54 (movable part 5b) moves in the X-axis direction, that is, in the radial direction of the loaded optical disk (tracking direction: radial). Direction).

Further, when the focusing coil 56 is energized, an electromagnetic force acts on the focusing coil 56, whereby the objective lens 54 (movable part 5b)
It moves in the axial direction, that is, in the optical axis direction of the objective lens 54 (focusing direction: reference axis direction).

For example, as shown in FIG. 6, when the lens holder 53 moves to the lower right in FIG. 6, it acts on the tracking coil 55, and rotates the movable portion 5b clockwise in FIG. The force (rotational force) F8 that acts on the focusing coil 56 and the force (rotational force) F9 that acts on the focusing coil 56 to rotate the movable part 5b clockwise in FIG. . Thereby, on the XZ plane, the optical axis 541 of the objective lens 54 and the reference axis (Z axis) become parallel. That is, the objective lens 54 (movable part 5)
The appropriate posture of b) is maintained.

Hereinafter, although the description is omitted, similarly,
Even if the objective lens 54 (movable part 5b) moves to an arbitrary position, the optical axis 541 of the objective lens 54 on the XZ plane
And the reference axis (Z axis) become parallel. That is, the appropriate posture of the objective lens 54 (movable part 5b) is maintained.

In recording (writing data) or reproducing (reading data), a laser beam is emitted from the laser diode of the optical pickup 1. This laser beam
The light is condensed by the objective lens 54 so as to have a predetermined beam diameter, and is irradiated on a rotating optical disk.

The reflected light from the optical disk is
The light is condensed by the objective lens 54, received by the photodiode, and photoelectrically converted. The signal from the photodiode is input to a predetermined circuit and processed.

As described above, according to the optical pickup 1, even if the objective lens 54 (movable part 5b) moves to an arbitrary position, the optical axis 541 of the objective lens 54 and the reference axis (Z axis) are not moved. Become parallel. That is, the objective lens 54
An appropriate posture of the (movable part 5b) is maintained.

As a result, recording and reproduction can be reliably performed on the optical disk, and particularly, recording and reproduction can be reliably performed on the high-density optical disk such as a DVD (digital video disk). Can be.

[0081]

EXAMPLE An optical pickup 1 shown in FIG. 1 was prepared and mounted on an optical disk device. The dimensions (see FIGS. 2 to 5) of each part of the optical pickup 1 thus prepared are as follows.

[Permanent magnet 52] H: 5.2 mm W: 6.0 mm D: 2.4 mm s: 0.5 mm t: 12.0 mm W / H: 1.15

[Yoke 51] p: 4.0 mm q: 1.0 mm r: 6.8 mm

[Tracking coil 55] a: 2.7 mm b: 1.5 mm c: 3.8 mm d: 2.6 mm e: 2.7 mm

[Focusing coil 56] f: 6.8 mm g: 2.0 mm h: 10.0 mm

Next, the tracking coil 55 and the focusing coil 56 of the optical pickup 1 are energized to move the objective lens 54 (movable part 5b) in the X-axis direction and Z-axis.
In the X-Z plane.
Axis), the inclination angle β of the optical axis 541 of the objective lens 54 was determined.

Further, the position of the objective lens 54 was changed and the inclination angle β was obtained. The measurement of the inclination angle β was performed evenly within a range in which the objective lens 54 could move.

As a result, the maximum inclination angle βmax in the XZ plane was 1.5 mrad.

Although the optical pickup according to the present invention has been described based on the illustrated embodiments and examples, the present invention is not limited to this, and the configuration of each part may be any arbitrary having the same function. It can be replaced with a configuration.

[0090]

As described above, according to the optical pickup of the present invention, even if the objective lens (lens holder) moves to an arbitrary position, the optical axis of the objective lens and the reference axis are substantially parallel. And the proper posture of the objective lens (lens holder) is maintained.

Thus, recording and reproduction can be reliably performed on the optical disk, and particularly, recording and reproduction can be surely performed on the high-density recording optical disk such as a DVD (digital video disk). Can be.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an optical pickup of the present invention.

FIG. 2 is a side view showing a yoke and a permanent magnet of the optical pickup shown in FIG.

FIG. 3 is a perspective view showing a permanent magnet of the optical pickup shown in FIG.

FIG. 4 is a front view schematically showing a tracking coil and a focusing coil of the optical pickup shown in FIG. 1;

FIG. 5 is a plan view schematically showing a yoke, a permanent magnet, a tracking coil, and a focusing coil of the optical pickup shown in FIG.

6 is a front view schematically showing a movable portion and a permanent magnet of the actuator of the optical pickup shown in FIG.

FIG. 7 is a side view showing a permanent magnet and a yoke of a conventional optical pickup.

FIG. 8 is a plan view showing a permanent magnet and a yoke of a conventional optical pickup.

FIG. 9 is a front view schematically showing a lens holder and a permanent magnet of a conventional optical pickup.

FIG. 10 is a diagram showing an inclination (inclination angle β in the XZ plane) of the optical axis of the objective lens from the reference axis (Z axis) when the lens holder is moved in the conventional optical pickup (one example) It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical pickup 2 Pickup base 21 Bottom surface 22, 23 Engagement claw 24 Projection 28, 29 Guide part 3 Actuator base 4 Damper base 5 Actuator 5a Fixed part 5b Movable part 51 Yoke 52 Permanent magnet 521 Surface 522 Short side 523 Long side 53 Lens Holder 531 Lens support 54 Objective lens 541 Optical axis 55 Tracking coil 56 Focusing coil 61 Straight line 7 Suspension wire 8 Substrate 110 Permanent magnet 120 Yoke 130 Lens holder 140 Tracking coil 150 Focusing coil 160 Objective lens 170 Optical axis 180 Reference axis

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenji Kato 5 Yamagata Mitsumi Co., Ltd., 1-1059-1 Tanigawa, Yamagata City (72) Inventor Hiroshi Sanbe 5-105-1 Tanigawa, Yamagata City, Yamagata 5 Mitsumi Yamagata Incorporated (72) Inventor Noriichi Oizumi 1-1059 Tanigawa, Yamagata City Yamagata Mitsumi Co., Ltd. F-term (reference) 5D118 AA13 BA01 BB01 BB03 BB05 EA02 EC07 ED03 ED07 ED08 FA27

Claims (10)

[Claims] 1. A tracking coil, a focusing coil, an objective lens, a lens holder for supporting the tracking coil, the focusing coil and the objective lens, and a displaceably supported lens holder via a plurality of suspension wires. An optical pickup having a damper base, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet mounted on the yoke, wherein the optical pickup acts on the tracking coil and / or the focusing coil. An optical pickup, wherein the shape of the magnet is set such that an electromagnetic force for tilting the optical axis of the objective lens from a reference axis substantially cancels out. 2. A tracking coil, a focusing coil, an objective lens, a lens holder that supports the tracking coil, the focusing coil and the objective lens, and a displaceable support of the lens holder via a plurality of suspension wires. An optical pickup having a damper base, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet mounted on the yoke, wherein the optical pickup acts on the tracking coil and emits light from the objective lens. An electromagnetic force that causes the axis to incline from the reference axis and an electromagnetic force that acts on the focusing coil and that causes the optical axis of the objective lens to incline from the reference axis substantially cancel out. Optical pickup characterized by its shape 3. A tracking coil, a focusing coil, an objective lens, a lens holder that supports the tracking coil, the focusing coil and the objective lens, and a displaceable support of the lens holder via a plurality of suspension wires. An optical pickup having a damper base, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet mounted on the yoke, and acting on the tracking coil and / or the focusing coil. An optical pickup characterized in that the shape of the magnet is set so that, of the electromagnetic force, a moment of a force around a straight line that is parallel to the suspension wire and passes through the center of gravity of the lens holder substantially cancels out. . 4. A tracking coil, a focusing coil, an objective lens, a lens holder for supporting the tracking coil, the focusing coil and the objective lens, and a displaceably supporting the lens holder via a plurality of suspension wires. An optical pickup having a damper base, a common yoke corresponding to the tracking coil and the focusing coil, and a magnet installed on the yoke, wherein the electromagnetic force acting on the tracking coil includes: The moment of the force around the straight line parallel to the suspension wire and passing through the center of gravity of the lens holder substantially cancels the moment of the force around the straight line among the electromagnetic forces acting on the focusing coil. So that the shape of the magnet Optical pickup is characterized in that setting the. 5. The optical pickup according to claim 1, wherein the magnet has a flat shape. 6. The optical pickup according to claim 1, wherein a shape of a surface of the magnet facing the tracking coil and the focusing coil is substantially rectangular. 7. The magnet such that a short side of a surface facing the tracking coil and the focusing coil is substantially parallel to the optical axis and a long side is substantially perpendicular to the suspension wire. The optical pickup according to claim 6, wherein the optical pickup is disposed. 8. A ratio W / a of a length H in a direction of the optical axis and a length W in a direction perpendicular to the optical axis of a surface of the magnet facing the tracking coil and the focusing coil. The optical pickup according to claim 6, wherein H is 1.10 to 1.32. 9. The optical pickup according to claim 1, wherein a maximum inclination angle of the optical axis from a reference axis is 2 mrad or less. 10. The yoke and the magnet,
The optical pickup according to claim 1, wherein a pair of the optical pickups is disposed at both ends of the lens holder via the objective lens.