JP2000082227A - Optical pickup and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup correctly operated by limiting the tilting amount of an objective lens within a permissible value irrespective of horizontal/ vertical mounting. SOLUTION: Assuming that each state of tracking coils 3a and 3b indicated by solid lines is in a deforming position equivalent to a self-distortion amount δ, a magnetic circuit 7 is positioned such that the center position P1 of a magnetic field such as a yoke 5 or the like is shifted by δ/2 with respect to the center P2 of the tracking coils 3a and 3b in such states. In other words, by estimating an offset amount generated in the case of vertical mounting and actively setting offset in a reverse direction at the time of horizontal mounting, an offset amount = a tilting amount is set within a permissible value in any of the cases as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, a CD-R
Not only OM but also CD-R / RW (Recordable / Rewrit
The present invention relates to an optical pickup used for recording / reproducing on an optical disc such as a digital versatile disc (DVD) and a DVD (Digital Versatile Disk) and an optical disc device using the same.

[0002]

2. Description of the Related Art Generally, in this type of optical disk device,
The laser beam is condensed and radiated on the optical disk as a minute spot through an objective lens in the optical pickup, and the reflected light is guided again to a predetermined detection optical system through the objective lens. In such a recording / playback operation,
The objective lens is configured to be driven by an objective lens actuator in an optical pickup in order to correctly track and focus the objective lens on the optical disc.

A general configuration example of such an objective lens actuator will be described with reference to FIG. That is, the objective lens actuator includes a lens holder 2 for holding the objective lens 1 and the lens holder 2 in a direction orthogonal to each other.
, And includes the yoke 5 and the magnets 6a, 6b. The focus coil 4 and the track coil 3 include the yoke 5 and the magnets 6a, 6b.
a magnetic circuit 7 for applying a magnetic field to a and 3b in a direction z orthogonal to the focus direction y and the track direction x;
The lens holder 2 mainly includes an elastic supporting member such as four wires 9 for supporting the pickup body 8 so as to be displaceable in the focus direction y and the track direction x. Although not particularly shown, the truck coil 3 is not shown.
Wires are provided so as to be able to appropriately energize a, 3b and the focusing coil 4.

Under such a configuration, the truck coil 3
Since the track coils 3a and 3b and the focus coil 4 receive a magnetic field from the magnetic circuit 7 including the magnets 6a and 6b, the track coils 3a or 3b and the focus coil 4 have currents of predetermined magnitude and direction, respectively. Flows, the lens holder 2 (therefore, the objective lens 1) is driven in the track direction x and the focus direction y.

In this case, the magnetic flux distribution of the magnetic field by the magnetic circuit 7 in the track direction has a strength center at the center of the magnetic circuit 7 in the track direction x as shown in FIG. Similarly, the magnetic flux distribution in the focus direction of the magnetic field by the magnetic circuit 7 is a distribution having an intensity center at the center of the magnetic circuit 7 in the focus direction y as shown in FIG.

As a result of having such a magnetic flux distribution, for example,
As shown in FIG. 9, the center C of the focusing coil 4 is shifted from the center O of the magnetic field by the magnetic circuit 7 in the track direction x.
If focusing is performed by the focusing coil 4 in a state of being shifted only by a certain amount, a moment acts upon focusing due to a shift in the center relation, and thus the lens holder 2 (the objective lens 1) is tilted. This is because, for example, as shown in FIG. 10, the track coils 3a and 3b are shifted from the center O of the magnetic field by the magnetic circuit 7 in the focus direction y by the shift amount C.
The same applies to the case of performing the tracking by a and 3b. Since a moment acts upon the tracking due to the deviation of the center relationship, the lens holder 2 (the objective lens 1) is tilted.

Here, in the case shown in FIG. 9, the displacement amount C in the track direction x (track position... Track coil 3)
qualitatively, the relationship between the track current for a and 3b) and the moment by the focusing coil 4 generated when a constant current for driving in the plus direction (positive direction of the focusing direction y) is applied to the focusing coil 4. Represents the characteristic as shown in FIG. Further, the shift amount C in the focus direction y in the case as shown in FIG.
(Focus position: proportional to the focus current for the focus coil 4) and the track coils 3a, 3b
, A track coil 3a, which is generated when a constant current for driving in the plus direction (the positive direction of the track direction x) flows.
3b qualitatively shows the relationship with the moment according to FIG.
The characteristics as shown in FIG. The direction of the moment is positive in the counterclockwise direction when viewed in the direction of arrow A in FIG. That is, according to the two characteristics shown in FIGS. 11A and 11B, it can be seen that the inclinations are in the opposite relationship.

Therefore, for example, FIG. 12 shows a configuration of the objective lens actuator viewed in the direction of arrow A in FIG.
Consider a case in which both the track direction x and the focus direction y are moved in the plus direction from the state in which the center positions shown in FIG. At this time, since a positive current is flowing through both the track coils 3a and 3b and the focusing coil 4, the moment by the focusing coil 4 is the fourth moment in FIG.
The direction corresponds to the quadrant, and the direction is negative. The moment by the truck coils 3a and 3b corresponds to the first quadrant in FIG. 11B, and the direction is positive. Therefore, since the moment by the focusing coil 4 and the moment by the track coils 3a and 3b are opposite to each other, they can cancel each other out and suppress the tilt caused by the moment. In any combination of plus / minus movement in the focus direction and plus / minus movement in the track direction, the moments of the focus coil 4 and the track coils 3a and 3b cancel each other. If the magnitude of the moment by the focusing coil 4 and the magnitude of the moment by the track coils 3a and 3b are completely matched, no tilt occurs due to the moment. Even if there is an error in the magnitude of each moment, they cancel each other out, so that the tilt can be kept within the allowable value as shown by the solid line in FIG.

Incidentally, this type of objective lens actuator or optical pickup is generally placed horizontally so that the focus direction is the vertical direction. Here, when the lens holder 2 supported by the wire 9 is placed horizontally with respect to the fixed yoke 5, the magnets 6a, 6b, etc., which are attached to the pickup main body 8, FIG.
As shown in (a), since the flexure is caused by its own weight, the positional relationship is set such that the centers of the track coils 3a and 3b coincide with the center position O of the magnetic field by the magnetic circuit 7 at the flexed position.

[0010]

In recent years, an optical disk apparatus equipped with an objective lens actuator or an optical pickup of this type has been increasingly used in a personal computer or the like. In this case as well, the optical pickup is generally placed horizontally so that the focus direction is the top and bottom direction. However, there is little demand that the optical pickup should be used vertically when the focus direction is the horizontal direction due to the installation space and the like. There are optical disk devices that can be placed vertically.

However, when the optical pickup with the conditions set in the state of FIG. 13A is used in a vertical position, the wire 9 does not bend due to the weight of the lens holder 2 due to its own weight, but FIG. As shown, the centers of the track coils 3a and 3b are shifted from the center of the magnetic field in the focusing direction by the elastic force of the wire 9. As a result, tracking is performed in a state shifted in the focus direction, and an offset is generated in the moment by the track coils 3a and 3b as shown in FIG. 14 with respect to the characteristic shown in FIG. 11B. That is, the moment by the focus coil 4 and the track coil 3
The moments a and 3b are not canceled out, and the amount of tilt increases.

Therefore, even if the tilt amount of the objective lens 1 is designed to be within an allowable value in the horizontal position under the condition that the track position (track current) is constant, when the objective lens 1 is used in the vertical position, the above-mentioned offset is used. Figure 1
As shown by a broken line in FIG. 5, the tilt amount of the objective lens 1 does not fall within the allowable value. If the amount of tilt exceeds the allowable value, focusing cannot be performed correctly on the optical disc, and a recording / reproducing operation, in particular, a recording operation cannot be normally performed.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical pickup and an optical disk apparatus which can normally operate the objective lens regardless of whether the objective lens is placed horizontally or vertically, within a permissible range.

[0014]

According to a first aspect of the present invention, there is provided an optical pickup, comprising: an objective lens; a lens holder for holding the objective lens; and the lens holder being displaced in a focus direction and a track direction with respect to the pickup body. An elastic supporting member for freely supporting, a focusing coil attached to the lens holder, a track coil attached to the lens holder, a yoke and a magnet including the magnet, and these focusing coil and track coil; An optical pickup comprising a magnetic circuit for applying a magnetic field in a direction perpendicular to the focus direction and the track direction with respect to the optical pickup, wherein the center of the magnetic field by the magnetic circuit and the center of the track coil are supported by the support member. Focus by half the amount of deflection of the lens holder in its focus direction I shifted in the direction.

Therefore, in the case of horizontal installation in which the self-weight deflection of the lens holder in the focus direction acts on the support member, the center of the magnetic field by the magnetic circuit and the center of the track coil are shifted in the focus direction by half of the self-weight deflection in the focus direction. Because of the deviation, the amount of tilt of the objective lens may be larger than in the case of coincidence, but it is easy to fall within the allowable value. On the other hand, in the case of the vertical setting in which the self-weight deflection of the lens holder in the focus direction does not act on the support member, the tilt offset amount of the objective lens with respect to the horizontal setting is halved. Can be stored. Therefore, the tilt amount of the objective lens can be kept within the allowable range regardless of whether the objective lens is placed horizontally or vertically, and normal operation can be performed.

According to a second aspect of the present invention, in the optical pickup according to the first aspect, the center position of the magnetic circuit and the center position of the track coil are focused by a half of the weight of the lens holder in the focusing direction. It was displaced in the direction. Therefore, it can be easily realized by the processing of the geometrical arrangement relationship in which the center positional relationship is shifted by half in consideration of the amount of deflection of the lens holder in its focus direction.

According to a third aspect of the present invention, in the optical pickup according to the first aspect, the center position of the magnetic field by the magnetic circuit is determined by the amount of deflection of its own weight in the focus direction of the lens holder with respect to the center position of the track coil. An auxiliary yoke that is shifted by half in the focus direction is provided. Therefore, even if the geometrical arrangement of the focusing coil and the magnetic circuit itself is not changed, it can be easily realized by shifting the magnetic field intensity distribution by a predetermined amount by imparting a bias to the magnetic field intensity distribution by the auxiliary yoke. it can.

According to a fourth aspect of the present invention, in the optical disk device, a pickup body is mounted so as to be able to move in a radial direction of the optical disk with a housing, a motor for rotating the optical disk, and an objective lens facing the optical disk. An optical pickup module having the optical pickup according to any one of claims 1 to 3, and a loading mechanism which is provided in the housing so as to be capable of moving forward and backward, and which holds the optical disk at a position facing the objective lens on the motor shaft. Therefore, the tilt amount of the objective lens can be kept within the allowable value regardless of the horizontal and vertical positions and normal operation can be performed.
Or the optical pickup module having the optical pickup described in 3 above, so that the
Good reproduction operation can be performed.

According to a fifth aspect of the present invention, in the optical disk device according to the fourth aspect, the optical pickup module can be freely selected between a horizontal position in which a focus direction is a vertical direction and a vertical position in which a focus direction is a horizontal direction. is there. Therefore, since the optical pickup module can be used regardless of whether it is placed horizontally or vertically, it is easy to use.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The same portions as those shown in FIGS. 7 to 15 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 shows an optical disc apparatus 1 to which the present embodiment is applied.
1, which has a flat box-shaped housing 12,
A disk tray 13 is provided which is housed in the housing 12 so as to be freely drawn out. This disc tray 13
Is used for loading / exchanging the optical disk 14 in the pulled-out state, forms a main body of a loading mechanism, and moves forward and backward based on the operation of the eject button 15. Such an optical disk device 11 has a configuration in which a horizontal arrangement as shown in FIG. 1A and a vertical arrangement as shown in FIG.

FIG. 2 is an exploded perspective view showing the structure of the optical pickup module 16 and the like built in the housing 12. 17 is a thin loading base,
The housing 12 is formed together with a top cover (not shown) assembled on the upper part. 18 is loading base 1
7, and an optical pickup module 16 is attached thereto. The optical pickup module 16 includes a substrate 19, a base chassis 20, and a cover 2.
1 is assembled into a unit. A motor 22 for rotating the optical disk 14 is provided on a substrate 19, and the motor 22 is supported by a base chassis 20 via the substrate 19. Further, the optical pickup main body 8 of the optical pickup 23 is slidably supported on the base chassis 20 in a direction orthogonal to the rotation axis of the motor 22 (radial direction of the optical disk = seek direction). This sliding operation is performed by a seek mechanism (not shown).

Here, the basic configuration itself of the optical pickup 23 including the objective lens 1 and the like is as described with reference to, for example, FIGS. Then, as shown in FIG. 3A, when the amount of deflection of the lens holder 2 supported by the wire 9 in the focus direction y is δ, in the present embodiment, as shown in FIG. The magnetic circuit 7 and the track coil 3a such that the center position P1 of the magnetic circuit 7 and the center position P2 of the track coils 3a and 3b are shifted from each other by half (= δ / 2) of the amount of self-weight deflection δ. , 3b. FIG. 4 is a partial view showing a state in which the main part is extracted, and the truck coils 3a,
Assuming that the state of 3b and the focus coil 4 is the deformed position corresponding to the amount of self-weight deflection δ, the center position P1 of the magnetic circuit 7 such as the yoke 5 is set to the center position P2 of the track coils 3a and 3b in this state. The magnetic circuit 7 is positioned so that the center position P1 is located at a position shifted by δ / 2 without being matched. That is, the center O of the magnetic field by the magnetic circuit 7
And the centers of the track coils 3a and 3b are set to be shifted in the focus direction y by half (= δ / 2) of the amount of self-weight deflection δ in the focus direction.

In such a configuration, a case is considered where the optical disk device 11 (optical pickup 23 and the like) is used horizontally as shown in FIG. In this case, as shown in FIG. 3A, the lens holder 2 supported by the wire 9 is bent by its own weight by an amount of its own weight bending δ. At this time, the center O (= P1) of the magnetic field by the magnetic circuit 7 and the center of the track coils 3a and 3b (= center position P2) are, as shown in FIG.
13 in the focus direction y.
(A), the tilt amount of the objective lens 1 is slightly larger than that in the case of coincidence as described with reference to FIG. 15, but falls within the allowable value as shown in FIG.

On the other hand, a case is considered where the optical disk device 11 (such as the optical pickup 23) is used in a vertical position as shown in FIG. In this case, the lens 9 does not bend with respect to the wire 9 due to its own weight. In the case of (1), an offset is generated. However, since it is not originally set to the matching state even in the horizontal position, even if the offset is generated, the offset appears in the direction in which the polarity changes as shown by the broken line in FIG. In this case, the tilt amount of the objective lens 1 falls within an allowable value even in the case of vertical placement as a whole. Conversely, in anticipation of the amount of offset that can occur in the case of vertical placement, by offsetting half of the positively in the reverse direction at the time of horizontal placement, the overall offset The amount = the tilt amount also falls within the allowable value. Therefore, according to the present embodiment,
Regardless of whether the lens is placed horizontally or vertically, the amount of tilt of the objective lens 1 can be kept within an allowable value, and the recording / reproducing operation on the optical disk 14 can be performed well.

In the present embodiment, the center is shifted by half the amount of its own weight deflection δ by properly setting the geometrical arrangement of the yoke 5 and the like. However, as shown in FIG. A portion connecting the horizontal portion of the yoke 5 (when placed horizontally) may be used as the auxiliary yoke 24 to substantially shift the center position P1 of the magnetic field of the magnetic circuit 7. That is, as shown in FIG. 6A, when the yoke 5 has the auxiliary yoke 24, the magnetic field distribution by the magnets 6a and 6b causes a leakage magnetic field to the auxiliary yoke 24 side. Is weaker, and the center of the overall intensity distribution shifts to the side without the auxiliary yoke 24. Since the amount of the leakage magnetic field increases as the auxiliary yoke 24 is closer to the magnets 6a and 6b, the shift amount can be adjusted depending on the position where the auxiliary yoke 24 is provided.
Therefore, if it is desired to shift the center position P1 on the side of the magnetic circuit 7 upward with respect to the center position P2 of the track coils 3a and 3b deformed by the weight deflection δ as in this embodiment, FIG. As shown by the solid line in FIG.
4 can be easily realized. Incidentally, if it is desired to shift the center position P1 on the magnetic circuit 7 side downward, as shown by the broken line in FIG.
5 may be provided.

[0026]

According to the optical pickup of the first aspect of the present invention, the center of the magnetic field and the center of the track coil by the magnetic circuit when the support member is horizontally placed in which the self-weight deflection in the focus direction of the lens holder acts on the support member. Is shifted in the focus direction by half the amount of its own weight deflection in the focus direction, so that the tilt amount of the objective lens may be slightly larger than in the case where they match, but it is easy to keep it within the allowable value, On the other hand, in the case of the vertical setting in which the self-weight deflection of the lens holder in the focus direction does not act on the support member, the tilt offset amount of the objective lens with respect to the horizontal setting is halved. The objective lens tilt amount can be kept within the allowable range, regardless of whether it is placed horizontally or vertically, so that it can operate normally. Kill.

According to a second aspect of the present invention, in the optical pickup according to the first aspect, the center position of the magnetic circuit and the center position of the track coil are shifted in the focus direction by half the amount of deflection of the lens holder in the focus direction. In this case, it is possible to easily realize the processing by a geometrical arrangement relationship in which the center positional relationship is shifted by half in consideration of the amount of deflection of the lens holder in its focus direction due to its own weight.

According to the third aspect of the present invention, in the optical pickup according to the first aspect, the center position of the magnetic field by the magnetic circuit is half the amount of deflection of its own weight in the focus direction of the lens holder with respect to the center position of the track coil. Auxiliary yoke that only shifts in the focusing direction is provided, so that the magnetic field intensity distribution is biased by the auxiliary yoke to shift the substantial center position of the magnetic field by a predetermined amount even if the arrangement relationship of the focusing coil and the magnetic circuit itself is unchanged. Can be easily realized.

According to the optical disk device of the fourth aspect,
The tilt amount of the objective lens is kept within an allowable value regardless of whether the objective lens is placed horizontally or vertically so that the objective lens can be operated normally.
Since the optical pickup module having the optical pickup described above is provided, the recording / reproducing operation for the optical disk can be performed satisfactorily.

According to the fifth aspect of the present invention, in the optical disk device according to the fourth aspect, the optical pickup module can be freely selected between a horizontal position where the focus direction is the vertical direction and a vertical position where the focus direction is the horizontal direction. Since the optical pickup module can be used regardless of whether it is placed horizontally or vertically, it is easy to use.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing an optical disk device according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a configuration of an optical pickup module and the like.

FIG. 3 is a schematic side view showing a positional relationship such as a center position with respect to an amount of deflection of its own weight.

FIG. 4 is a partial side view extracting and showing a main part thereof.

FIG. 5 shows focus current in horizontal and vertical placements.
It is a lens tilt characteristic diagram.

6A and 6B show a modified example, in which FIG. 6A is a principle view and FIG. 6B is a schematic side view.

FIG. 7 is a schematic plan view showing a general configuration example of an objective lens actuator.

8 (a) is a schematic plan view including a magnetic flux distribution, and FIG. 8 (b) is a schematic side view including a magnetic flux distribution.

FIG. 9 is a schematic plan view showing a state of being shifted in a track direction.

FIG. 10 is a schematic side view showing a state of being shifted in a focus direction.

11A is a characteristic diagram illustrating a moment of a focusing coil with respect to a deviation amount in a track direction, and FIG. 11B is a characteristic diagram illustrating a moment of the tracking coil with respect to a deviation amount in a focusing direction.

FIG. 12 is a diagram viewed from an arrow A in FIG. 7 for explaining a canceling method based on the above characteristics.

FIG. 13 is a schematic side view showing a state of deformation in the case of horizontal placement and vertical placement.

FIG. 14 is a characteristic diagram showing a moment offset generated in the case of vertical placement.

FIG. 15 is a focus current-lens tilt characteristic diagram for explaining a defect in the case of vertical placement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3a, 3b Track coil 4 Focusing coil 5 Yoke 6a, 6b Magnet 7 Magnetic circuit 8 Pickup main body 9 Support member 12 Housing 13 Loading mechanism 14 Optical disk 16 Optical pickup module 23 Optical pickup δ Self-weight deflection amount x Track direction y Focus direction

Claims (5)

[Claims] An objective lens; a lens holder for holding the objective lens; an elastic support member for supporting the lens holder so as to be displaceable in a focus direction and a track direction with respect to a pickup body; An attached focusing coil, a track coil attached to the lens holder, a yoke and a magnet, which include a magnetic field in a direction orthogonal to the focus direction and the track direction with respect to the focus coil and the track coil. An optical pickup including a magnetic circuit to be operated, wherein a center of a magnetic field by the magnetic circuit and a center of the track coil are focused by a half of an amount of deflection of its own weight in a focus direction of the lens holder supported by the support member. An optical pickup characterized by being shifted in a direction. 2. The apparatus according to claim 1, wherein a center position of the magnetic circuit and a center position of the track coil are displaced in the focus direction by half of the amount of deflection of the lens holder in its focus direction. Optical pickup as described. 3. An auxiliary yoke for displacing a center position of a magnetic field by the magnetic circuit in a focus direction by a half of a weight of a lens holder in a focus direction with respect to a center position of the track coil. The optical pickup according to claim 1. 4. A housing, a motor for rotating the optical disk, and a pickup main body mounted to be slidable in a radial direction of the optical disk with an objective lens facing the optical disk.
An optical disc device comprising: an optical pickup module having the optical pickup according to 2 or 3; and a loading mechanism provided in the housing so as to be able to advance and retreat, and holding the optical disc at a position facing the objective lens on the motor shaft. . 5. The optical pickup module according to claim 4, wherein the optical pickup module is selectable between a horizontal position in which a focus direction is a vertical direction and a vertical position in which a focus direction is a horizontal direction.
An optical disk device as described in the above.