KR19980087045A - Objective lens driving device - Google Patents

Abstract

The objective lens driving device has a base disposed opposite to the optical disk, the objective lens in one end, and is provided on the base in such a manner as to be freely movable in the direction perpendicular to the recording surface of the optical disk and in the radial direction of the optical disk. A holder, and drive means for moving the lens holder in the two directions. The base and the lens holder are connected by a tracking plate spring that is radially relaxed to the recording surface of the optical disk, a focusing plate spring that is relaxed in a direction perpendicular to the recording surface of the optical disk, and a connecting member provided between each of these springs. The driving means is disposed between the objective lens held by the lens holder and the connecting member.

Description

Objective lens driving device

The present invention relates to an objective lens driving device, in particular an objective lens driving device used in an optical disk device.

The conventional objective lens driving device is described in connection with the objective lens driving device 50 shown in FIG.

In Fig. 3, an example of a conventional objective lens driving device shown in, for example, Japanese Unexamined Patent Publication No. 5-101427 or Japanese Unexamined Patent Publication No. 8-77586 is shown, and reference numeral 51 denotes an optical. The objective lens of the optical head used in the disk apparatus is shown, and the objective lens 51 is supported in a manner fixed to the moving part 52.

This moving part 52 is supported by the fixing part 54 through four wires 53 so that the focusing direction (Z direction in FIG. 3 which is perpendicular to the recording surface of the optical disk) and the track direction (radius of the optical disk). Direction in the X direction).

That is, each wire 53 is parallel to the Y direction (the direction perpendicular to both the X direction and the Z direction), each one end is linked to the moving part 52, and the other end is connected to the fixing part 54. Is supported by.

The magnetic circuit 55 for pushing the moving parts in the X and Z directions is provided between the moving parts 52 and the fixing part 54.

However, in the conventional objective lens driving device 50, since each wire 53 supporting the moving part 52 is round bar-shaped to relax in the X direction and the Z direction. Even if the moving part 52 is moved in the focus direction Z and the track direction X, movement is impossible unless the wire 53 is twisted when moving in the track direction X, and the hardness of the moving part 52 is increased. ), And since the objective lens 51 is also tilted, stable reading and writing become impossible in this case.

On the other hand, Japanese Unexamined Patent Publication Nos. 63-121140 and 61-182642 disclose an objective lens driving unit in which a lens holder is connected to a rotating member capable of rotating magnetically with respect to a fixed rotating shaft. And the rotating member can be returned to its original position by the tracking leaf spring, the size of the objective lens drive unit is enlarged and the mechanism becomes more complicated.

In view of the above drawbacks of the prior art, it is an object of the present invention to provide an objective lens driving device which can suppress the hardness, in particular, when the objective lens is moved in the track direction.

In order to achieve the above object, the basic technical configuration of the present invention comprises: an objective lens driving apparatus for driving a laser condensing objective lens used for illuminating light on a recording surface of an optical disk, the objective lens having a base disposed opposite the optical disk; A lens holder mounted to the base to hold the objective lens by one end and to be freely movable in a direction perpendicular to the recording surface of the optical disk and in a radial direction with respect to the optical disk; And a driving means for pushing the lens holder in the two directions, the base and lens holder comprising: a tracking plate spring that relaxes in the radial direction of the optical disk, a focusing plate spring that relaxes in a direction perpendicular to the recording surface of the optical disk; It is linked through a connecting member provided between the springs.

Another feature of the present invention is that, in the objective lens driving device, the driving means is disposed between the objective lens supported by the lens holder and the connecting member.

When the objective lens is moved in a direction perpendicular to the recording surface of the optical disc (hereinafter, focus direction) to adjust the focus, the focusing plate spring pushed by the driving means is relaxed, and the lens holder moves accordingly.

Moving the objective lens (also known as tracking) in the radial direction of the optical disc (hereafter the focusing direction) to adjust the point at which the light shines, the tracking plate spring propelled by the driving means relaxes, and the lens holder Move along.

According to another technical feature of the present invention, an objective lens driving device includes a base disposed opposite the optical disk; A lens holder which holds the objective lens by one end and is provided on the base in such a manner as to be freely movable in a direction perpendicular to the recording surface of the optical disk and in a radial direction of the optical disk; And drive means for promoting movement of the lens holder in the two directions, wherein the base and the lens holder are linked through a tracking plate spring that relaxes in the radial direction of the optical disk.

1A and 1B are a plan view and a front view of an embodiment of the present invention.

2 is a plan view of the lens holder;

3 is a perspective view of a conventional objective lens driving device.

4 (A) and 4 (B) show an embodiment of a tracking leaf spring used in the present invention.

5 is an outline view of a monitoring test for the hardness of the objective lens.

6 shows the results of the monitoring test shown in FIG. 5 for the present invention.

7 and 8 show the results of the monitoring test shown in FIG. 5 for a conventional objective lens drive device.

Explanation of symbols for the main parts of the drawings

2: lens holder

3: driving means

10: objective lens driving device

11: objective lens

12: Base

12a: support plate

13: tracking plate spring

14: focusing plate spring

15: connection member

31: focus direction drive coil

32: track direction drive coil

33: coil bobbin

34: magnet

35, 36: York

This embodiment provides an objective for driving an objective lens 11 used for condensing laser light in an optical disk apparatus that illuminates light from a light source in a vertical direction on a recording surface of the optical disk through a reflection mirror to perform reading and writing. It is shown as a lens drive device 10.

The objective lens driving device 10 includes a base 12 disposed opposite the optical disk; Holding the objective lens 11 in one end, the direction on the recording surface of the optical disk (focus direction Z shown in FIG. 1B) and the radial direction of the optical disk (track direction shown in FIG. 1A). A lens holder 2 mounted on the base 12 to move freely inclined around the other end with X); And driving means for promoting movement of the lens holder in the two directions.

In more detail with respect to each of the above elements, the base 12 is a flat element provided parallel to the recording surface of the optical disc (not shown), which is installed on the head moving mechanism of the optical disc device (not shown). The rotational motion of the optical disk in the radial direction is promoted.

By this reciprocating motion, the position at which the laser light is irradiated to the selected track formed on the recording surface of the optical disk is set.

In relation to this base 12, the lens holder 2 is capable of freely moving in the focusing direction Z and the tracking direction X, so that the intermediate tracking leaf spring 13, the focusing leaf spring 14 and the connecting member 15 can be freely moved. Through the base 12.

More specifically, the support plate 12a, which is upright to have a posture perpendicular to the base 12, and the connecting member 15 are linked through the tracking plate spring 13.

This tracking plate spring 13 has a curved surface arranged so as to be perpendicular to the recording surface of the optical disk and to be tangential to the track formed on the recording surface of the optical disk (Y direction in FIG. 1A). The supporting plate 12a and the connecting member 15 are linked by two ends.

By using this arrangement, since the tracking plate spring 13 is bent around the focusing direction between the support plate 12a and the connecting member 15, the lens holder 2 with the connecting member 15 in the track direction X. To move in line.

The connecting member 15 and the lens holder 2 are linked by four focusing leaf springs 14 at four points.

These focusing leaf springs 14 have curved surfaces arranged to be parallel to the recording surface of the optical disk and along the Y direction, and the connecting member 15 and the lens holder 2 are linked by two ends.

By using this arrangement, since the focusing plate spring 14 is bent around the track direction X between the connecting member 15 and the lens holder 2, the lens holder moves in the focusing direction Z with respect to the connecting member 15. do.

Since the lens holder 2 is supported at four points by the four focusing leaf springs 14, when moving along the focus direction Z, the objective lens 11 supported by the lens holder 2 is connected to the connecting member ( 15) Rather than rotating around, it moves parallel to the focusing direction Z, so that the optical axis always remains parallel to the focusing direction Z.

In addition, the lens holder 2 is formed in a closed frame shape or almost annular shape, wherein the objective lens 11 is held in the closed frame shape or annular portion such that the optical axis is parallel to the focus direction Z.

Each focusing leaf spring 14 is linked to the top and bottom surfaces of the lens holder 2 of FIG. 1B so as to be equidistant from the objective lens 11. The drive means 3 are arranged in a closed frame form or annular part of this lens holder 2.

The drive means 3 is a focus direction drive coil 31 for pushing the lens holder 2 in all directions along the focus direction Z, and a track direction drive for pushing the lens holder 2 in all directions along the track direction X. The coil 32, the coils 31 and 32 are formed by a coil bobbin 33 provided as a unit, and a magnet 34 and a yoke 35 and 36 as magnetic circuits.

The focus direction drive coil 31 and the track direction drive coil 32 are mounted on the lens holder 2 via the coil corbin 33.

2 is a plan view of the coil bobbin 33. As shown in FIG. 2, the coil bobbin 33 has a lens holder 2 holding portion 33a at both ends and a through hole 33b, through which the yoke 35 passes with a margin. , Which is formed at its center.

The area surrounding the through hole 33b is wound by the focus direction drive coil 31, and a total of four track direction drive coils 32 are provided on both side surfaces in the area close to the end.

Since this coil bobbin 33 is fixedly held inside the substantially annular portion of the lens holder 2 by the holder holding portion 33a, the longitudinal direction is positioned so that it is arranged along the track direction X, which is also the same way. Position each of the coils 31 and 32 along the track direction X. FIG.

Two magnets 34 are provided on the base 12 through the yoke 36 to surround the coil bobbin 33.

Each magnet 34 is set to a predetermined length so as to oppose the track direction drive coils 32 provided in the regions at both ends of the coil bobbin 33.

The yoke 36 provided on the base is in contact with both ends of the magnets 34 to hold each of them. As described above, the yoke 35 is erected on the base 12 at a position that is loosely inserted through the through hole 33b of the coil bobbin 33.

Each of the yokes 35 and 36 is formed by making a cutout of a predetermined shape in the base 12 which is a magnetic body, but is formed integrally with the base 12.

However, there is no particular limitation on this arrangement, and it can also be fixed to the base as individual elements.

The operation of the objective lens driving device 10 configured as described above will be described later.

In the case of moving the objective lens 11 along the focus direction Z and the track direction X, the movement is performed by using the four focusing leaf springs 14 and the tracking leaf springs 13.

Since the tracking plate spring 13 is provided in an arrangement relationship along the direction Y perpendicular to the track direction X between the connecting member 15 and the base 12 support plate 12a and perpendicular to the recording surface of the optical disk, the curved surface Is bent along the direction along the focusing direction Z, and the objective lens 11 supported by the lens holder 2 via the connecting member 15 moves along the track direction X. FIG.

By moving the objective lens 11 in this way, the position of the laser beam passing through is finely adjusted along the track direction X.

Since the focusing leaf spring is provided in an arrangement relationship parallel to the recording surface of the optical disc and along the direction Y perpendicular to the track direction X between the connecting member 15 and the lens holder 2, the curved surface follows the track direction X. The direction is bent along the axis, whereby the objective lens 11 supported by the lens holder 2 is moved by moving along the focus direction Z with respect to the connecting member 15.

By moving the objective lens 11 in this way, the focal length of the laser beam passing through is finely adjusted.

In the above embodiment of the present invention, as shown in Fig. 4A, a tracking leaf spring that can be used in this embodiment is shown as an example.

According to another embodiment of the objective lens driving apparatus of the present invention, the following technical concept may be used, that is, the objective lens driving apparatus includes a base disposed to face the optical disk; A lens holder mounted to the base to hold the objective lens by one end and to be freely movable in a direction perpendicular to the recording surface of the optical disk and in a radial direction with respect to the optical disk; And drive means for promoting movement of the lens holder in the two directions, the lens holder being linked through a tracking plate spring that relaxes in the radial direction of the optical disk.

It should be noted that in the present invention, the base and the lens holder are connected to each other only through the tracking plate spring without using the rotating shaft as the support means.

Thus, in the objective lens driving device according to the present invention, one end of the tracking plate spring is connected to the fixing member protruding from the main surface of the base, while the other end of the tracking plate spring is connected to the lens holder by the connecting member. It is connected to the member to form a closed space S surrounded by the connecting member, the lens holder and the connecting member.

Further, the connecting member 15 is connected to the lens holder 2 via a plurality of focusing leaf springs 14 as connecting members, each of which is relaxed in a direction perpendicular to the recording surface of the optical disk.

In the present invention, the center of rotation of the lens holder 2 along the surface of the optical disc is disposed in the closed space.

Furthermore, in the present invention, the tracking leaf spring may comprise a plurality of sub-tracking leaf springs 13a, 13b, 13c, 13d, ... shown in FIG. 4B, which are separated from each other.

The sub-tracking leaf spring can be used for a data terminal through which a data signal can be passed to drive each of the coils provided in the drive means.

According to the invention, as described above, when moving the lens holder 2 in the track direction X and the focus direction Z, the individual tracking and focusing leaf springs 13 and 14 correspond to these movements.

Since the leaf springs 13 and 14 both have a predetermined width, they can be bent in a predetermined fixed direction as an axis in response to an external force, so that twisting or the like is suppressed.

For this reason, when the objective lens 11 is moved in the track direction X and the focus direction Z, the corresponding individual leaf springs 13 and 14 are bent in the inherent direction, effectively suppressing the twisting.

In this way, the hardness of the lens holder 2 generated in the past by the track X movement is particularly prevented, thereby enabling stable reading and writing.

Since the driving means 3 are arranged between the objective lens 11 and the connecting member 15, the driving means 3 are lasered from the opposite side of the optical disk toward the objective lens 11, which surrounds the objective lens 11. The distance between the reflective mirror reflecting light and the objective lens 11 can not be prevented and the distance between the reflective mirror and the objective lens 11 can be shortened.

Therefore, the objective lens drive device 10 according to the present invention can be thinned, and the optical disk device provided with the present invention can be thinned.

In particular, since the lens holder is annular, it is easy to set a space in which the driving means can be disposed.

In addition, since the four focusing leaf springs 14 are provided with lens holders 2 supported at four points, and the lens holders 2 are moved by relaxation in the respective leaf springs 13 and 14. As such, the lens holder 2 can be moved by parallel movement without hardness, thereby suppressing an instantaneous misadjustment at the point of incidence of the laser light when focused.

Since the track direction drive coil 32 and the focus direction drive coil 31 are provided in parallel along the track direction via the coil bobbin 33, the space between the objective lens 11 and the connecting member 15 can be shortened. It is possible to reduce the size of the device in this direction.

As mentioned above, the present invention has separate tracking and focusing leaf springs corresponding to the movement of the lens holder in the track direction and the focus direction, respectively.

Since each of the leaf springs has a predetermined width, it can only be bent in a predetermined fixed direction in response to an external force, and twisting or the like is effectively suppressed.

For this reason, when the objective lens is moved in the track direction and the focus direction, the corresponding individual leaf springs are bent in their own direction, making it possible to effectively suppress twisting such as occurred in the wire in the past.

In this way, the hardness of the lens holder is prevented, enabling stable reading and writing.

Since the driving means is disposed between the objective lens and the connecting member, as compared with the case where the driving means is arranged in the area surrounding the objective lens, when the present invention is installed in the optical disk apparatus, the driving means is a light which surrounds the objective lens. The distance between the reflection mirror and the objective lens can be shortened by not intervening between the reflection mirror and the objective lens for reflecting the laser light from the opposite side of the disc to the objective lens.

Therefore, the thinning of the objective lens driving device of the present invention can be achieved, and the thinning of the optical disk device provided with the present invention can also be achieved by expanding the analysis.

In particular, since the lens holder has an annular shape, it is easy to set a space in which the driving means can be placed in the inner space, in which case the driving means is placed on top of the lens holder or the driving means on the bottom of the lens holder. Compared to the case of arranging the above, the objective lens driving device can be significantly thinned.

In addition, since the four focusing leaf springs are provided with lens holders supported at four points, and since the lens holders are moved by the relaxation of each spring, the lens holders are moved by parallel movement without hardness, when focused Instantaneous error control at the point of incidence of the laser light can be suppressed.

When the track direction drive coil and the focus direction drive coil are provided in parallel along the track direction through the unit, the space between the objective lens and the connecting member can be shortened, thereby making it possible to thin the device in this direction.

As described above, the present invention provides an excellent objective lens driving apparatus that has not been available in the past.

The effects obtained by the present invention are described below with reference to FIGS. 5 to 8.

According to an exemplary test conducted by the inventor of the present invention, the hardness of the objective lens is monitored when it is shifted by a predetermined distance from the center position (normal position) of the objective lens. The conventional objective lens driving apparatus of FIG. 3 manufactured by

The monitoring test was done as follows:

Using the objective lens drive device shown in FIG. 5, which corresponds to that shown in FIG. 1 and the conventional one shown in FIG. 3, the lens holder 3 supplies a certain amount of current to each drive coil, thereby providing a focus direction. Intentionally shifted from the center (normal) position in either of two directions, such as (Fcs) and track direction (Trk), and by ± 0.3 mm in both directions, respectively.

In Fig. 5, in relation to the focus direction Fcs, the sign + indicates the direction toward the surface of the optical disk, while-indicates the direction away from the surface of the optical disk.

On the other hand, with respect to the track direction Trk, the sign + indicates the direction toward the center of the optical disk, while-indicates the direction away from the center of the optical disk.

FIG. 6 shows the monitoring test results, and each chart shown in FIG. 6 shows how the objective lens is inclined by shifting a certain amount of distance from the center of the objective lens.

It should be noted that, for example, chart (a) of FIG. 6 shows, in minutes, as indicated by the black circle when the objective lens is shifted from the center by + 0.3 mm in the focus direction and-0.3 mm in the track direction. It represents the inclination angle of the objective lens in both directions.

Therefore, the chart (a) of FIG. 6 shows that the objective lens is inclined at about 2 minutes or less in the focus direction and about 3 minutes or less in the track direction.

It should be noted that the remaining charts (b) to (h) of FIG. 6 show similar hardness results of the objective lens of the present invention, and from these results of the monitoring test, the level of the hardness of the objective lens of the present invention is small. It is clear that it can be suppressed within.

On the other hand, in Figs. 7 and 8, similar monitoring results obtained from conventional objective lens driving apparatuses manufactured by Company A and Company B are shown, respectively.

It is clear from these tests that the hardness of the objective lens of the conventional objective lens driving device in both directions is relatively larger than that of the present invention, and therefore it is clear that the objective lens when the present invention is shifted compared to the conventional ones. It has a significant effect in suppressing the hardness of.

Claims (12)

An objective lens driving device for driving an objective lens for focusing laser light emitted on a recording surface of an optical disk, comprising: a base disposed to face the optical disk; A lens holder mounted to the base to hold the objective lens by one end and to freely move the objective lens in a direction perpendicular to the recording surface of the optical disk and in a radial direction with respect to the optical disk. ; And driving means for driving the movement of the lens holder in the two directions, wherein the base and the lens holder are tracking plate springs that relax in the radial direction of the optical disk, a direction perpendicular to the recording surface of the optical disk. And a linking plate spring which is relaxed by means of a spring and a connecting member provided between the springs. The objective lens drive device according to claim 1, wherein the driving means is disposed between the objective lens supported by the lens holder and the connection member. 2. The tracking plate spring of claim 1, wherein the tracking plate spring is provided to have a curved surface perpendicular to the recording surface of the optical disk, and the focusing leaf spring is arranged to have a curved surface parallel to the recording surface of the optical disk. Objective lens drive device. The objective lens driving device of claim 1, wherein four focusing plate springs are provided to connect the connecting member and the lens holder. The lens holder according to claim 1, wherein the lens holder is formed in a closed frame shape, the objective lens is disposed on a part of the closing frame, and the driving means is inside the closed frame of the lens holder. The objective lens driving device, characterized in that arranged. 2. A focusing drive coil according to claim 1, wherein said drive means drives a longitudinal direction movement coil to incline movement from said recording surface of said optical disk to said lens holder in a vertical direction, and along said radial direction with respect to said optical disk. A track direction drive coil for driving longitudinal movement to said lens holder, said lens holder having said focus direction drive coil and said track direction drive coil arranged in series along said radial direction with respect to said optical disk; The objective lens drive device characterized by the above-mentioned. An objective lens driving device for driving an objective lens for focusing laser light emitted on a recording surface of an optical disk, comprising: a base disposed to face the optical disk; A lens holder mounted to the base to hold the objective lens by one end and to freely move the objective lens in a direction perpendicular to the recording surface of the optical disk and in a radial direction with respect to the optical disk. ; And driving means for driving the movement of the lens holder in the two directions, wherein the base and the lens holder are linked through a tracking plate spring that relaxes in the radial direction of the optical disk. Device. 8. A connection member according to claim 7, wherein one end of the tracking plate spring is connected to a fixing member protruding from the main surface of the base, while the other end of the tracking plate spring is connected to the connecting member connected to the lens holder by a connecting member. Connected to form a closed space surrounded by the connection member, the lens holder and the connection member. 9. The connecting member according to claim 8, wherein the connecting member is connected to the lens holder through the plurality of focusing plate springs as the connecting member, and each of the focusing plate springs is relaxed in a direction perpendicular to the recording surface of the optical disc. Objective lens drive device. 9. The objective lens drive device according to claim 8, wherein the rotation center of the lens holder along the surface of the optical disc is disposed in the closed space. 8. The objective lens driving device according to claim 7, wherein the tracking plate spring comprises a plurality of sub-tracking plate springs which are separated from each other. 12. The objective lens driving apparatus of claim 11, wherein each of the sub-tracking leaf springs is used in a data terminal through which a data signal for driving each of the coils provided in the driving means can be passed.