KR100329934B1 - Pickup Actuator - Google Patents

Abstract

A pickup actuator for use in an optical recording and reproducing apparatus is disclosed. The disclosed pickup actuator includes a pickup base; A lens holder mounted to the base member to mount the objective lens and to move in the focusing and tracking direction; Holder driving means for driving the lens holder in the focusing and tracking direction; And a damping fluid applied between the lens holder and the holder driving means to damp vibrations generated in the lens holder when the lens holder is driven by the holder driving means. The holder driving means includes a pair of first yokes installed at regular intervals on both sides of an axis of the base member; A pair of second yokes which are provided on the outside of the first yoke at regular intervals and have a substantially semicircular shape; A pair of first magnets attached to one side of the second yoke so as to face each other; A pair of second magnets attached to the other side of the second yoke so as to face each other; And a drive coil installed in the lens holder for electromagnetic interaction with the first and second magnets. The damping fluid may be applied between the first magnet and the focusing coil of the lens holder, or may be applied between the second magnet and the tracking coil of the lens holder and may be applied to both places. According to this, since the vibration generated in the lens holder is immediately attenuated by the damping fluid of the present invention, the objective lens can be reached more quickly at the target point.

Description

Pickup actuator

The present invention relates to a pickup actuator for use in an optical recording and reproducing apparatus for recording and / or reproducing predetermined information on an optical disc using optical means.

The field of recording and reproducing information by using optical means on a recording medium such as an optical disc has attracted attention as a future technology. In such an optical recording and reproducing apparatus, the pickup actuator is a very important component that determines the speed of recording and reading information. The pickup actuator is largely comprised of a base member, a lens holder mounted with an objective lens so as to be movable relative to the base member, and lens holder driving means for moving the lens holder in a focusing and tracking direction.

A typical example of such a pickup actuator is shown in FIGS. 1 to 4, which will be described below.

1 is a perspective view of a detached state of a lens holder showing a conventional pickup actuator, FIG. 2 is an assembled perspective view of the pickup actuator shown in FIG. 1, FIG. 3 is a cross-sectional view taken along line AA of the pickup actuator shown in FIG. 2, and FIG. BB line sectional drawing of the pickup actuator shown in FIG.

In the drawings, reference numeral 10 is a base member, and 20 is a lens holder.

The base member 10 has an axis 11 that is set up at a predetermined height from its center toward the upper side. In addition, the base member 10 is provided with a pair of first yoke 12, 12 'and second yoke 13, 13' on both sides of the shaft 11 at regular intervals. have. The pair of first yokes 12 and 12 'is rectangular, and the second yokes 13 and 13' are substantially semi-circular.

In addition, a pair of first magnets 14 and 14 ′ are attached to inner surfaces of the second yokes 13 and 13 ′ facing each other at positions corresponding to the first yokes 12 and 12 ′. At a position adjacent to the first magnets 14 and 14 ', a pair of second magnets 15 and 15' having curved portions 15a are attached to face each other. The first and second magnets 14, 14 ′, 15, 15 ′ form a predetermined magnetic circuit and the first and second yokes 12, 12 ′, 13, 13 ′ ) Maximizes the magnetic flux density of the magnets 14, 14 ′, 15, 15 ′ in the direction of required.

The lens holder 20 is provided to be movable relative to the base member 10 by fitting the shaft hole 20a formed in the center portion thereof to the shaft 11 of the base member 10.

An objective lens 22 is mounted on the lens holder 20, and a pair of through holes for penetrating the first yokes 12 and 12 ′ provided in the base member 10 on both sides of the shaft hole 20a. 20b and 20c are formed.

In addition, the lens holder 20 has a driving coil 30 constituting the lens holder driving means together with the first and second magnets 14, 14 ', 15 and 15'. The driving coil 30 includes a pair of focusing coils 32 and 32 'wound at positions corresponding to the first magnets 14 and 14' on both sides of the lens holder 20, and the lens holder 20. The tracking coils 34 and 34 'are wound at positions corresponding to the second magnets 15 and 15' on both sides.

The pickup actuator configured as described above is formed by electromagnetic interaction by the magnets 14, 14 ', 15 and 15' and the focusing and tracking coils 32, 32 ', 34 and 34'. The lens holder 20 is moved in the focusing and tracking direction to perform the focusing and tracking operation of the objective lens 22.

However, in the conventional pickup actuator as described above, the lens holder 20 has the first and second magnets 14, 14 ', 15, 15', and the focusing and tracking coils 32, 32 '. Since it is movably supported with respect to the base member 10 by (34) (34) ', the vibration generate | occur | produces in the focusing and tracking operation of the objective lens 22, and this causes the objective lens 22 to target It takes considerable time to reach the point stably.

This will be described in more detail with reference to FIG. 5. In FIG. 5, the vertical axis s represents a distance to which the objective lens 22 must move to reach the target point, and the horizontal axis t represents a time taken for the objective lens 22 to reach the target point.

"Ga" in FIG. 5 is a diagram showing ideal movement of the objective lens 22. FIG. In this case, the objective lens 22 takes a time of "0" to reach the target point "T". However, this case is practically impossible because the speed of the objective lens 22 (the slope of the diagram " Ga ") must have an infinite value instantaneously.

"Gb" in FIG. 5 is one of the diagrams showing the realistic movement of the objective lens 22. In this case, as shown, it takes a predetermined time "t _b " for the objective lens 22 to stably reach the target point "T".

If the feed speed of the objective lens 22 is increased to reduce this time "t _b ", the time taken for the objective lens 22 to reach the target point "T" as shown by "Gc" in FIG. It is possible to reduce from "t _b " to "t _c ", but in this case, the objective lens 22 inevitably undergoes severe vibration.

As such, the vibration experienced by the objective lens 22 increases as the moving speed of the objective lens 22 increases. Therefore, effectively attenuating this vibration allows the objective lens 22 to reach the target point "T" sooner.

However, the conventional pickup actuator does not employ a structure that attenuates the vibration inevitably generated in the lens holder during focusing and tracking of the objective lens, so that it takes a long time for the objective lens to stably reach the target point. there was.

In particular, when a severe vibration such as an optical recording and reproducing apparatus for a vehicle or a physical shock is applied to the optical recording and reproducing apparatus, the vibration generated in the lens holder 20 is not rapidly attenuated by this. There was also a problem such as malfunction of the optical recording / reproducing apparatus.

The present invention has been made to solve the above problems, by providing a pickup actuator that can quickly reach the target point of the objective lens by rapidly attenuating the vibration generated in the lens holder during the focusing and tracking operation. There is this.

Another object of the present invention is to provide a pickup actuator capable of preventing a malfunction of an optical recording / reproducing apparatus due to vibration by rapidly attenuating vibration generated in the lens holder due to vibration or shock from the outside.

Figure 1 is a perspective view of the lens holder detachment state showing a conventional pickup actuator.

FIG. 2 is an assembled perspective view of the pickup actuator shown in FIG. 1. FIG.

3 is a cross-sectional view taken along the line A-A showing the main configuration of the pickup actuator shown in FIG.

4 is a sectional view taken along the line B-B of the pickup actuator shown in FIG.

FIG. 5 is a diagram for explaining a vibration relationship with time taken for an objective lens to reach a target point for focusing and tracking in a general pickup actuator. FIG.

6 is a perspective view showing a pickup actuator according to an embodiment of the present invention.

FIG. 7 is a sectional view of principal parts of the pickup actuator shown in FIG. 6; FIG.

8 is a view corresponding to FIG. 5 for explaining a damping effect by the damping fluid of the present invention. FIG.

Figure 9a is a perspective view of a pickup actuator according to another embodiment of the present invention.

9B is a sectional view of FIG. 9A;

10 is a perspective view showing a pickup actuator according to another embodiment of the present invention.

11 is a perspective view showing a pickup actuator according to another embodiment of the present invention.

12 is a sectional view of principal parts of the pickup actuator shown in FIG. 11;

Explanation of symbols on the main parts of the drawings

10; base member 11; shaft

12,12 '; first yoke 12a; blocking jaw of the first yoke

13,13 '; 2nd yoke 14,14'; 1st magnet

15,15 '; second magnet 20; lens holder

20a; shaft hole 20b, 20c; through hole

22; objective 32,32 'focusing coil

Tracking coil 50; damping fluid

The pickup actuator according to the present invention for achieving the above object is generated in the lens holder during the driving of the lens holder between the base member as the fixing member and the lens holder as the flow member for the base member. It is characterized by applying a damping fluid for damping vibration.

Here, the damping fluid is preferably a magnetic fluid having a viscosity range of about 1000 cP to 2000 cP at an ambient temperature of about 27 ° C. and capable of magnetizing from about 3 to 4 kOe of magnetic field strength to about 100 G or more and 200 G. Therefore, when the magnetic fluid is applied to the magnet part, it exhibits a sufficient damping effect on the flow member while maintaining a cohesive state without flowing down or spreading to other parts.

According to a preferred embodiment of the present invention, the pickup actuator comprises: a base member; A lens holder mounted to the base member to mount the objective lens and to move in the focusing and tracking direction; Holder driving means for driving the lens holder in the focusing and tracking direction; And a damping fluid applied between the lens holder and the holder driving means to damp vibrations generated in the lens holder when the lens holder is driven by the holder driving means.

Here, the holder driving means comprises a pair of first yokes installed at regular intervals on both sides of the axis of the base member; A pair of second yokes which are provided on the outside of the first yoke at regular intervals and have a substantially semicircular shape; A pair of first magnets attached to one side of the second yoke so as to face each other; A pair of second magnets attached to the other side of the second yoke so as to face each other; And a drive coil installed in the lens holder for electromagnetic interaction with the first and second magnets.

The damping fluid may be applied between the first magnet and the focusing coil of the lens holder, or may be applied between the second magnet and the tracking coil of the lens holder and may be applied to both places.

According to another preferred embodiment of the invention, the damping fluid may be applied between the lens holder and the first yoke. At this time, the first yoke is preferably provided with means for preventing the damping fluid from being drawn to the magnet side.

According to the pickup actuator of the present invention, even if vibration occurs in the lens holder for any reason, the vibration is immediately attenuated by the damping fluid applied between the magnet and the lens holder or the yoke and the lens holder, To reach the target faster.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

6 is a perspective view showing a pickup actuator according to an embodiment of the present invention, Figure 7 is a cross-sectional view of the main portion of the pickup actuator shown in Figure 6, Figure 8 is for explaining the damping effect of the damping fluid of the present invention Drawing.

For reference, in describing the embodiments of the present invention, the same reference numerals refer to the same parts as those in the related art. Accordingly, in the drawings, reference numeral 10 denotes a base member, 12 and 12 'are first yokes, 13 and 13' are second yokes, 14 and 14 'are first magnets, and 15 and 15' are second magnets. Reference numeral 20 is a lens holder and 30 is a drive coil. Reference numeral 50 is a damping fluid.

As shown in Figs. 6 and 7, the base member 10 has an axis 11 set up at a predetermined height from its center toward the upper side. In addition, the base member 10 is provided with a pair of first yoke 12, 12 'and second yoke 13, 13' on both sides of the shaft 11 at regular intervals. have. The pair of first yokes 12 and 12 'is rectangular, and the second yokes 13 and 13' are substantially semi-circular.

In addition, a pair of first magnets 14 and 14 ′ are attached to inner surfaces of the second yokes 13 and 13 ′ facing each other at positions corresponding to the first yokes 12 and 12 ′. At a position adjacent to the first magnets 14 and 14 ', a pair of second magnets 15 and 15' having curved portions 15a are attached to face each other. The first and second magnets 14, 14 ′, 15, 15 ′ form a predetermined magnetic circuit and the first and second yokes 12, 12 ′, 13, 13 ′ ) Maximizes the magnetic flux density of the magnets 14, 14 ′, 15, 15 ′ in the direction of required.

The lens holder 20 is provided to be movable relative to the base member 10 by fitting the shaft hole 20a formed in the center portion thereof to the shaft 11 of the base member 10.

An objective lens 22 is mounted on the lens holder 20, and a pair of through holes for penetrating the first yokes 12 and 12 ′ provided in the base member 10 on both sides of the shaft hole 20a. 20b and 20c are formed.

In addition, the lens holder 20 has a driving coil 30 constituting the lens holder driving means together with the first and second magnets 14, 14 ', 15 and 15'. The driving coil 30 includes a pair of focusing coils 32 and 32 'wound at positions corresponding to the first magnets 14 and 14' on both sides of the lens holder 20, and the lens holder 20. The tracking coils 34 and 34 'are wound at positions corresponding to the second magnets 15 and 15' on both sides.

The damping fluid 50 is applied between the pair of first magnets 14, 14 ′ and the focusing coils 32, 32 ′ provided on both sides of the lens holder 20. (32) It is apply | coated so that it may fully contact 32 '. The damping fluid 50 serves to damp the vibration generated in the lens holder 20 when the lens holder 20 is driven, that is, when the lens holder 20 moves in the focusing and tracking direction.

The damping fluid 50 may be a magnetic fluid in which magnetic particles are not separated from the fluid even when a considerable centrifugal force or magnetic field is applied to the fluid, more specifically, a colloidal solution in which ferromagnetic ultrafine particles are stably dispersed in the liquid. Herein, Fe ₃ O ₄ may be used as the magnetic particles.

In addition, the damping fluid 50 preferably has a viscosity range of about 1000 cP to 2000 cP at an ambient temperature of about 27 ° C., and may be magnetized to about 100 G or more and 200 G at a magnetic field strength of about 3 to 4 kOe.

Therefore, the damping fluid 50 damps the vibration of the lens holder 20 due to its viscosity, and also the magnet 14, 14 'and the lens holder 20 do not flow downward due to the magnetism. It is maintained properly between.

Such a pickup actuator is a lens by electromagnetic interaction by the magnets 14, 14 ', 15, 15' and the focusing and tracking coils 32, 32 ', 34 and 34'. The holder 20 is moved in the focusing and tracking direction to perform the focusing and tracking operation of the objective lens 22.

At this time, vibration is generated in the lens holder 20 for the same reason as described above in the prior art. However, this vibration starts to be attenuated immediately by the damping fluid 50 interposed between the magnets 14 and 14 'and the lens holder 20 almost simultaneously with the occurrence.

Thus, as indicated by the leading "Ge" in Figure 8, a conventional objective lens 22 compared to the (leading "Gc" of Fig. 8), the time "t _e until a stable reach the" T "at a target location Is significantly shortened.

9A and 9B are perspective views and cross-sectional views illustrating a pickup actuator according to another embodiment of the present invention.

As shown, the pick-up actuator according to another embodiment of the present invention is a pair of tracking damping fluid 50 is provided with a pair of the second magnet 15, 15 'and the lens holder 20, both sides Except that it is applied between the coils 34 and 34 ', it has the same structure as the embodiment of the present invention described above.

In addition, the damping fluid 50 of the present invention, as shown in Fig. 10, between the first magnet 14, 14 'and the focusing coils 32, 32' of the lens holder 20 and the second It may be applied to both the magnets 15 and 15 'and the tracking coils 34 and 34' of the lens holder 20. Even in this case, the damping effect of the lens holder 20 as in the embodiments of the present invention described above can be obtained.

In addition, the damping fluid 50 of the present invention may be applied between the first yoke 12, 12 'and the through holes 20b, 20c of the lens holder 20, as shown in FIG. Even in this case, the damping effect of the lens holder 20 as in the exemplary embodiments of the present invention described above can be obtained. However, in this case, since the damping fluid 20 is a magnetic fluid, the damping fluid 20 cannot be held between the yoke 12, 12 ′ and the lens holder 20, and can be drawn to the magnets 14, 14 ′ on the left and right sides thereof. have. Therefore, in the present embodiment, the damping fluid 20 is formed in the yoke 12, 12 ′ to prevent the damping fluid 20 from passing to another place, that is, the magnet 14, 14 ′, thereby damping. The fluid 20 is appropriately held between the yoke 12, 12 ′ and the lens holder 20 to damp the vibration of the lens holder 20. FIG. 12 is a cross-sectional view of FIG. 11, specifically showing the structure of the blocking jaw portion 12a of the yoke 12, 12 ′. Other configurations and operations are the same as in the other embodiments described above, and thus detailed description thereof will be omitted.

As described above, according to the pickup actuator of the present invention, even if vibration occurs in the lens holder during focusing and tracking operation, the vibration is immediately attenuated by a damping fluid applied between the magnet and the lens holder or the yoke and the lens holder. Therefore, the objective lens can be reached at the target point faster.

In particular, the pickup actuator of the present invention can effectively dampen the lens holder as described above, even when vibration occurs in the lens holder due to vibration or shock from the outside, so that the pickup actuator suffers severe vibration such as an automobile. There is an advantage that it is excellent in adaptability to the optical recording / reproducing apparatus used.

In addition, since the pickup actuator of the present invention can effectively cool the heat generated from the drive coil during the focusing and tracking driving through the damping fluid, it is possible to prevent the deterioration of the pickup actuator due to the heat and damage to the optical pickup. There is also an advantage.

On the other hand, in the examples, two pairs of magnets 14, 14 ′, 15, 15 ′ are provided in the yoke 12, 12 ′, 13, 13 ′ of the base member 10, In addition, although the focusing coils 32, 32 'and the tracking coils 34, 34' are installed in the lens holder 20, the present invention is not applied only to the pickup actuator of the magnetic circuit type. The same applies to other magnetic circuit type pickup actuators.

In addition, in the embodiments of the present invention, a magnetic fluid is illustrated as a damping fluid, but the damping fluid is not limited to the illustrated magnetic fluid, and any application may be applied to any fluid capable of performing the same function as the damping fluid of the present invention. It will be possible.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described claims, and the present invention is not limited to the scope of the present invention. Of course, any person skilled in the art can make various modifications, and such modifications fall within the scope of the claims.

Claims (4)

A base member; A lens holder mounted to the base member on which an objective lens is mounted and which can move in a focusing and tracking direction; A pair of first yokes installed at regular intervals on both sides of an axis of the base member; A pair of second yokes provided at an outer side of said first yoke at regular intervals and having a substantially semicircular shape; A pair of first magnets attached to one side of the second yoke to face each other; A pair of second magnets attached to the other side of the second yoke to face each other; And A pair of focusing coils installed at both sides of the lens holder to allow electromagnetic interaction with the first magnet; A pair of tracking coils installed adjacent to the focusing coil of the lens holder to allow electromagnetic interaction with the second magnet; And And a damping fluid applied between the pair of first magnets and the focusing coil of the lens holder to damp vibration generated in the lens holder when the lens holder is driven. The damping fluid has a viscosity range of about 1000 cP to 2000 cP at an ambient temperature of about 27 ° C., and a pickup actuator, which is a magnetic fluid capable of magnetizing from about 3 to 4 kOe of about 100 G or more to 200 G. A base member; A lens holder mounted to the base member on which an objective lens is mounted and which can move in a focusing and tracking direction; A pair of first yokes installed at regular intervals on both sides of an axis of the base member; A pair of second yokes provided at an outer side of said first yoke at regular intervals and having a substantially semicircular shape; A pair of first magnets attached to one side of the second yoke to face each other; A pair of second magnets attached to the other side of the second yoke to face each other; And A pair of focusing coils installed at both sides of the lens holder to allow electromagnetic interaction with the first magnet; A pair of tracking coils installed adjacent to the focusing coil of the lens holder to allow electromagnetic interaction with the second magnet; And And a damping fluid applied between the pair of second magnets and the tracking coil of the lens holder to damp vibration generated in the lens holder when the lens holder is driven. The damping fluid has a viscosity range of about 1000 cP to 2000 cP at an ambient temperature of about 27 ° C., and a pickup actuator, which is a magnetic fluid capable of magnetizing from about 3 to 40 kOe to about 100 G or more and 200 G. A base member; A lens holder mounted to the base member on which an objective lens is mounted and which can move in a focusing and tracking direction; A pair of first yokes installed at regular intervals on both sides of an axis of the base member; A pair of second yokes provided at an outer side of said first yoke at regular intervals and having a substantially semicircular shape; A pair of first magnets attached to one side of the second yoke to face each other; A pair of second magnets attached to the other side of the second yoke to face each other; And A pair of focusing coils installed at both sides of the lens holder to allow electromagnetic interaction with the first magnet; A pair of tracking coils installed adjacent to the focusing coil of the lens holder to allow electromagnetic interaction with the second magnet; And Vibration generated in the lens holder during driving of the lens holder is applied to both the pair of first magnet and the focusing coil of the lens holder and between the pair of second magnet and the tracking coil of the lens holder. It includes; Damping fluid for damping the The damping fluid has a viscosity range of about 1000 cP to 2000 cP at an ambient temperature of about 27 ° C., and a pickup actuator, which is a magnetic fluid capable of magnetizing up to about 100 G or more and 200 G at a magnetic field strength of about 3 to 4 kOe. A base member; A lens holder mounted to the base member on which an objective lens is mounted and which can move in a focusing and tracking direction; A pair of first yokes installed at regular intervals on both sides of an axis of the base member; A pair of second yokes provided at an outer side of said first yoke at regular intervals and having a substantially semicircular shape; A pair of first magnets attached to one side of the second yoke to face each other; A pair of second magnets attached to the other side of the second yoke to face each other; And A pair of focusing coils installed at both sides of the lens holder to allow electromagnetic interaction with the first magnet; A pair of tracking coils installed adjacent to the focusing coil of the lens holder to allow electromagnetic interaction with the second magnet; A damping fluid applied between a pair of through holes formed in the lens holder and a pair of first yokes penetrating the damper to damp vibration generated in the lens holder when the lens holder is driven; And And a blocking jaw portion installed at each of the pair of first yokes to prevent magnetic fluid applied to the pair of first yokes from being drawn to the first magnet side. The damping fluid has a viscosity range of about 1000 cP to 2000 cP at an ambient temperature of about 27 ° C., and a pickup actuator, which is a magnetic fluid capable of magnetizing up to about 100 G or more and 200 G at a magnetic field strength of about 3 to 4 kOe.