JP2002175635A - Objective lens driving device, and optical pickup or optical information recording and reproducing device loaded with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a range of adjusting the inclination in the tangential direction of a disk, in an objective lens driving device, without degrading the performance (sensitivity, dynamic range, etc.), of the driving device. SOLUTION: The wire supporting center of a holder is arranged in the direction away from the disk relative to the wire supporting center of a bobbin, and also, a magnetic circuit is tilted in accordance with that inclination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an objective lens driving device used for a disk drive.

[0002]

2. Description of the Related Art In an objective lens driving device used in a disk device, an example of a measure for reducing the relative inclination between a disk and a lens is disclosed in Japanese Patent Application Laid-Open No. Hei 8-1066.

[0003]

The objective lens driving device drives and displaces the objective lens in a direction parallel to the optical axis and in a direction perpendicular to the optical axis in accordance with the focusing error signal and the tracking error signal. The light emitted through the objective lens is converged on the disk surface by following the surface deflection of the disk due to rotation, the meandering of the track, and the eccentricity. Further, the objective lens driving device is attached to a pickup case, and the pickup case is held by a moving unit so as to be movable in a radial direction of the disk. With the movement of this pickup case,
The objective lens driving device can also move between the innermost circumference and the outermost circumference of the data area on the disk.

When reproducing or recording data on a disk by an objective lens driving device and an optical device, if the optical axis of the objective lens and the objective lens are inclined, spots formed on the disk will have aberrations. appear. Also,
Even when the objective lens and the disc are relatively inclined,
An aberration is generated in a spot formed on the disk.
For this reason, it is necessary to minimize the inclination between the optical axis of the objective lens and the objective lens and the relative inclination between the objective lens and the disk. In particular, in recent years, there is a tendency to use an objective lens having a large numerical aperture in order to improve the recording density of an optical disk device. For this reason, strict accuracy is required for the relative angle shift amount between the objective lens and the disk. However, there are usually assembly errors and part manufacturing errors,
Attach the objective lens drive to the pickup case,
Further, while attaching the pickup case to the moving means, the objective lens is assembled in a state of being inclined with respect to the disk surface. Therefore, a method of providing an adjusting mechanism for adjusting the inclination of the entire objective lens driving device and adjusting the optical axis of the objective lens so as to be perpendicular to the disk surface by this adjusting mechanism during assembly is used.

The objective lens driving device described in the above prior art also adjusts the tilt of the objective lens by this method.
During the adjustment, the tilt of the objective lens is adjusted by rotating the objective lens driving device about a certain point. However, in the above-described conventional adjustment mechanism, the center of rotation coincides with the principal point of the lens. Not. For this reason, at the time of adjustment, the position of the optical axis of the light incident on the objective lens and the position of the principal point of the objective lens are shifted.

In order to solve this problem, generally, the objective lens is rotated around the principal point of the objective lens, and adjustment is performed so that the optical axis of the objective lens is perpendicular to the disk surface. The adjustment is performed by tilting the objective lens in the disk radial direction and the track tangential direction. At this time, the bobbin on which the objective lens is mounted, the support member having one end attached to the bobbin, and the holder attached to the other end of the support member are centered on the principal point of the objective lens with the tilt adjustment of the objective lens. To rotate. Among these components that rotate together with the objective lens, the component that is the longest from the principal point of the objective lens is the holder. Therefore, the holder is most displaced by adjusting the tilt of the objective lens. However,
Optical disk devices are becoming smaller and thinner in consideration of mounting on notebook computers. For this reason, the optical pickup is required to be extremely thin. Therefore, the holder cannot be largely displaced in the thickness direction of the optical pickup by adjusting the tilt of the objective lens. Therefore, there is a problem that the width of the adjustment becomes extremely small and a desired reproduction signal cannot be obtained.

[0007]

In order to solve the above problems, an objective lens driving device according to the present invention and an optical pickup or an optical information recording / reproducing device equipped with the same are provided.
An objective lens for recording or reproducing information on a disc, a bobbin holding the objective lens, a focusing coil generating a driving force for driving the bobbin in a focusing direction, and generating a driving force for driving the bobbin in a tracking direction A tracking coil, a magnetic circuit that generates a magnetic flux acting on the focusing coil and the tracking coil, a support member that supports the bobbin at one end, and a holder that supports the other end of the support member. In a state where the lens is located at a predetermined working distance from the disk, the support center of the support member in the holder is positioned in the optical axis direction of the objective lens with respect to the support center of the support member in the bobbin. , In a direction away from the disk.

[0008] A straight line connecting the support center of the support member in the holder and the support center of the support member in the bobbin indicates that the objective lens is located at a predetermined working distance from the disk. The hobbin is inclined at a predetermined angle with respect to a plane parallel to the disk, and the direction of movement of the hobbin in the focusing direction is perpendicular to the straight line.

The optical axis of the objective lens is substantially perpendicular to the disk, and the focusing coil,
A surface formed by a wire element that generates a driving force of the tracking coil is inclined at a predetermined angle with respect to the optical axis direction of the objective lens, and the predetermined angle is determined by the angle of the support of the support member in the holder. The straight line connecting the center and the support center of the support member on the bobbin is substantially equal to the inclination angle with respect to a plane parallel to the disk when the objective lens is located at a predetermined working distance from the disk. I do.

The direction of the magnetic flux generated by the magnetic circuit is perpendicular to the plane formed by the wire elements that generate the driving force of the focusing coil and the tracking coil, and the direction of the magnetic flux is determined by the direction of the holder. It is parallel to a straight line connecting the support center of the support member and the support center of the support member on the bobbin.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 11 is a perspective view showing the pickup 1 . Objective lens driving device 1 in pickup case 11
2 is mounted. Furthermore, the pick-up case 11
An optical component (not shown) is mounted. The light beam formed by the optical components is focused on the information recording surface of the disc (not shown) by the objective lens 2 to form a light spot.

FIG. 12 is an exploded perspective view showing the objective lens driving device 12 . An object lens 2 is mounted on the bobbin 3, and a focusing coil 4 is arranged at the center of the bobbin 3. Focusing coil 4
Is composed of an air-core coil having a rectangular cross section. On one surface of the focusing coil 4, 2
The tracking coil 5 which connects two coils is attached. The tracking coil 5 is a rectangular air-core coil. The objective lens 2, bobbin 3, focusing coil 4, and tracking coil 5 move integrally. The ends of the focusing coil 4 and the tracking coil 5 are electrically connected to four elastic wires 8.

Reference numeral 6 denotes a yoke. The yoke 6 has rising portions 6a and 6b. The magnets 7 are attached to the yoke rising portions 6b, respectively.

The objective lens driving device 12 supports the bobbin 3 using four wires. These four wires 8
Are arranged substantially in parallel. The fixed points of the wire 8 on the bobbin 3 are arranged at the positions of the four vertices of the rectangle. 9 is a holder. Reference numeral 10 denotes a substrate adhered and fixed to the holder 9. The four wires 8 are fixed to the substrate with a conductive adhesive such as solder. Thereby, the bobbin 3 is cantilevered by the holder 9 by the wire 8. The fixing points of the wires 8 on the substrate 10 are arranged at the positions of the four vertices of the rectangle, similarly to the bobbin 3.

FIG. 13 shows the relationship between the fixed positions of the wire 8, the bobbin 3 and the substrate 10. As described above, the wire 8 includes the bobbin 3 and the four vertices f1, f2,
It is fixed at f3 and f4. The wire 8 is connected to the holder 9
And the four vertices s of the rectangle
It is fixed at 1, s2, s3, and s4. Here, bobbin 3
Gf is the intersection of the diagonal lines of the rectangle f1f3f3f4 indicating the fixed point of, and the rectangle s1s2s3s indicating the fixed point of the substrate 10
The intersection of the four diagonals is Gs.

FIG. 6 shows a side sectional view of the pickup 1. The focusing coil 4 and the tracking coil 5 are positioned so as to be sandwiched between the magnets 7 attached to the rising portions 6a and 6b of the yoke 6. Lv indicates a direction perpendicular to the disc (not shown), that is, a focusing direction. When an electric current is applied to the focus coil 4 and the tracking coil 5 via the wire 8, the electric current flows in a magnetic flux created by a magnetic circuit constituted by the yoke 6 and the magnet 7, and thus the bobbin 3 on which the objective lens 2 is mounted is displaced. Force is generated. This force causes the objective lens 2 to move in a direction perpendicular to the disk and in a radial direction of the disk. An optical component (not shown) is mounted on the pickup case 11, and a light beam is raised so as to take an optical axis in a direction perpendicular to a disc (not shown). The direction of this optical axis is defined as Lv.

FIG. 6 shows an ideal state in which the parts are assembled without error. Therefore, the optical axis of the objective lens 2 coincides with the optical axis Lv of an optical system formed by an optical component (not shown) mounted on the pickup case 11. As described above, this Lv is in a direction perpendicular to the disk. A straight line connecting the point Gf and the point Gs shown in FIG. 13 coincides with a straight line Lh orthogonal to the optical axis Lv. That is, the straight line connecting the point Gf and the point Gs is parallel to the disk surface. Furthermore, this straight line is
Is parallel to the bottom surface.

FIG. 7 shows a case where the objective lens 2 is attached to the bobbin 3 at an angle. The inclination angle at this time is defined as θ4. This inclination is an inclination in the tangential direction of the disk. When the objective lens 2 is tilted from the optical axis Lv, spots on the disk undergo aberration, and no good signal can be obtained. Therefore, the optical axis of the objective lens 2 and the optical axis Lv of the optical system
Is adjusted to rotate the objective lens 2.
For this adjustment, the objective lens driving device 12 is rotated about the principal point Gh of the objective lens 2 in the disk tangential direction. This is because the center of the objective lens 2 does not deviate from the optical axis Lv.

FIG. 8 shows a state in which the objective lens driving device 12 is rotated counterclockwise from the position shown in FIG. 7 around the point Gh. In this state, the optical axis of the objective lens 2 matches the optical axis Lv of the optical system. The rotation angle is the inclination angle θ between the optical axis of the objective lens 2 and the optical axis Lv of the optical system shown in FIG.
It becomes 4. Therefore, the straight line connecting the point Gf and the point Gs and the straight line L
The angle formed with h is θ4. In this state, the bottom surface of the holder 9 has reached the bottom surface of the pickup case 11,
No further rotation adjustment in this direction is possible. That is,
The adjustment is full of the adjustment range.

On the other hand, FIG. 9 shows a case where the objective lens 2 is attached to the bobbin 2 in a direction opposite to that of FIG. The inclination angle at this time is defined as θ5. Also in this case, the rotation of the objective lens 2 is adjusted in order to make the optical axis of the objective lens 2 coincide with the optical axis Lv of the optical system. The rotation angle is θδ. Therefore, the angle formed by the straight line connecting the point Gf and the point Gs and the straight line Lh is θδ. In this state, the upper surface of the holder 9 has reached the upper surface of the pickup case 11, and the rotation cannot be further adjusted in this direction. However, θ5 <
Because of θδ, the optical axis of the objective lens 2 and the optical axis Lv of the optical system still have an inclination of θ5−θδ even in this state. For this reason, the spot on the disk has an aberration.

Here, .theta.4 and .theta.5 are equal in magnitude and are opposite amounts of inclination. However, in the case of θ4, the adjustment was possible, whereas in the case of θ5, the adjustment was not completed. This is because in FIG. 6, the clearance between the upper surface of the holder 9 and the upper surface of the pickup case 11 is significantly smaller than the clearance between the bottom surface of the holder 9 and the bottom surface of the pickup case 11. For this reason, there is a difference in the adjustment range depending on the direction of displacement (inclination) of attachment of the objective lens 2 to the bobbin 3, and the objective lens 2
The variation between the case where the inclination adjustment is possible and the case where the inclination cannot be adjusted becomes large.

FIG. 1 is a side sectional view of a pickup 1 according to an embodiment of the present invention. The straight line connecting the points Gf and Gs shown in FIG. 13 is fixed so as to be inclined with respect to the straight line Lh by a predetermined angle θ1. That is, the point Gs becomes the point Gf
Rather than the disk. The wire 8 is also inclined by an angle θ1 with the straight line Lh. That is, the wire 8 and the bottom surface of the pickup case 11 are inclined by θ1. Therefore, the clearance between the upper surface of the holder 9 and the upper surface of the pickup case 11 is substantially equal to the clearance between the bottom surface of the holder 9 and the bottom surface of the pickup case 11.

FIG. 1 shows an ideal state in which the parts are assembled without errors. In this state, the optical axis of the objective lens 2 matches the optical axis Lv of the optical system. The optical axis of the objective lens 2 is not orthogonal to the straight line connecting the points Gf and Gs.

Next, FIG. 2 shows a case where the objective lens 2 is attached to the bobbin 3 at an angle. The inclination angle at this time is defined as θ2. The rotation of the objective lens 2 is adjusted to match the optical axis of the objective lens 2 with the optical axis Lv of the optical system. For this adjustment, the objective lens driving device 12 is rotated about the principal point Gh of the objective lens 2.

FIG. 3 shows a state in which the objective lens driving device 12 is rotated counterclockwise from the position shown in FIG. 2 around the point Gh. In this state, the optical axis of the objective lens 2 matches the optical axis Lv of the optical system. The rotation angle is the inclination angle θ between the optical axis of the objective lens 2 and the optical axis Lv of the optical system shown in FIG.
It becomes 2. Therefore, the straight line connecting the point Gf and the point Gs and the straight line L
h and the adjustment angle θ2 shown in FIG.
And θ1 + θ2. In this state, the bottom surface of the holder 9 reaches the bottom surface of the pickup case 11, and the rotation cannot be further adjusted in this direction.

On the other hand, FIG. 4 shows a case where the objective lens 2 is attached to the bobbin 2 in a direction opposite to that of FIG. The inclination angle at this time is defined as θ3. Also in this case, the rotation of the objective lens 2 is adjusted in order to make the optical axis of the objective lens 2 coincide with the optical axis Lv of the optical system.

FIG. 5 shows a state in which the objective lens driving device 12 is rotated clockwise from the position shown in FIG. 4 around the point Gh. In this state, the optical axis of the objective lens 2 matches the optical axis Lv of the optical system. The rotation angle is the inclination angle θ3 between the optical axis of the objective lens 2 and the optical axis Lv of the optical system shown in FIG.
Becomes Therefore, the straight line connecting the point Gf and the point Gs and the straight line Lh
Is an angle obtained by adding θ1 shown in FIG. 1 to the adjustment angle θ3, and θ1 + θ3 (θ1 and θ3 have opposite signs). In this state, the upper surface of the holder 9 has reached the upper surface of the pickup case 11, and the rotation cannot be further adjusted in this direction.

Here, .theta.2 and .theta.3 are equal in magnitude and are oppositely inclined amounts. That is, even if the direction of the displacement (inclination) of the attachment of the objective lens 2 to the bobbin 3 is different, there is no difference in the adjustment range, and there is a case where the inclination of the objective lens 2 can be adjusted and a case where it cannot be adjusted completely. Variations are eliminated.

However, the adjustment was possible in the case of θ4, but not in the case of θ5. This is shown in FIG.
In this case, the clearance between the upper surface of the holder 9 and the upper surface of the pickup case 11 is significantly smaller than the clearance between the bottom surface of the holder 9 and the lower surface of the pickup case 11.

In the present embodiment, four wires 8
Are all arranged in parallel, but for the distances f1f2 and f3f4 in FIG. 13, s1s2 and s3s4
It is needless to say that the same effect can be obtained even when the arrangement of the wires 8 is not parallel, such as by increasing the distance.

FIG. 14 is a schematic block diagram of a disk device equipped with the optical pickup of the present invention. Various detection signals detected by the optical pickup 508 are transmitted to the servo signal generation circuit 504 and the information signal reproduction circuit 5 in the signal processing circuit.
05. The servo signal generation circuit 504 generates a focus error signal and a tracking error signal suitable for each optical disc from these detection signals, and drives the objective lens actuator in the optical pickup 508 via the actuator drive circuit 503 based on these. Controls the position of the objective lens. Further, the information signal reproducing circuit 505
Then, the information signal recorded on the optical disc 1 is reproduced from the detection signal. Note that some of the signals obtained by the servo signal generation circuit 504 and the information signal reproduction circuit 505 are sent to the control circuit 500. Control circuit 50
0 uses the various signals to determine the type of the optical disc 1 to be reproduced at that time, and drives either the DVD laser lighting circuit 507 or the CD laser lighting circuit 506 according to the determination result. As described above, the servo signal generation circuit 504 selects the servo signal detection method according to the type of each optical disc.
Has the function of switching the circuit configuration of The control circuit 500 is connected to an access control circuit 502 and a spindle motor drive circuit 501, and controls the access direction position of the optical pickup 508 and the rotation of the spindle motor 509 of the optical disk 1, respectively.

According to the present embodiment, when the optical axis of the objective lens deviates from the optical axis of the optical system due to an assembly error of the objective lens driving device, the objective lens driving device is rotated to align the above optical axis. In the adjustment, a sufficient adjustment range can be secured. Further, the adjustment range is not biased depending on the direction of the assembly error. Further, since the magnetic circuit is inclined in accordance with the angle at which the straight line connecting the point Gf and the point Gs is inclined, the above adjustment does not reduce the magnetic gap of the objective lens driving device.

[0034]

As described above, according to the present invention, even if an assembly error occurs in the objective lens driving device, the optical axis of the objective lens and the light of the optical system can be maintained without deteriorating the performance of the objective lens driving device. A good spot can be formed on the signal recording surface of the disc along with the axis, and a good signal can be obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of an objective lens driving device according to the present invention.

FIG. 2 is a side sectional view showing an embodiment of the objective lens driving device of the present invention.

FIG. 3 is a side sectional view showing an embodiment of the objective lens driving device of the present invention.

FIG. 4 is a side sectional view showing an embodiment of the objective lens driving device of the present invention.

FIG. 5 is a side sectional view showing an embodiment of the objective lens driving device of the present invention.

FIG. 6 is a side sectional view of the objective lens driving device.

FIG. 7 is a side sectional view of the objective lens driving device.

FIG. 8 is a side sectional view of the objective lens driving device.

FIG. 9 is a side sectional view of the objective lens driving device.

FIG. 10 is a side sectional view of the objective lens driving device.

FIG. 11 is a perspective view of a pickup equipped with the objective lens driving device of the present invention.

FIG. 12 is an exploded perspective view of the objective lens driving device of the present invention.

FIG. 13 is a perspective view showing a stretched state of a wire of the objective lens driving device of the present invention.

FIG. 14 is a schematic block diagram of a disk device equipped with a pickup of the present invention.

[Explanation of symbols]

1 ... pickup, 2 ... objective lens, 3 ... bobbin, 4 ...
Focusing coil, 5 ... Tracking coil, 6 ...
Yoke, 7: magnet, 8: wire, 9: holder, 1
0: substrate, 11: pickup case, 12: objective lens driving device.

Continued on the front page (72) Inventor Nobuyuki Maeda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. Digital Media Development Division, Hitachi, Ltd. Inside Hitachi Media Electronics (72) Inventor Hiroshi Ogasawara 1 Kitano, Majo, Mizusawa City, Iwate Prefecture Inside Hitachi Media Electronics Co., Ltd. (72) Inventor Mitsuo Satake 1 Kitano, Majo, Mizusawa City, Iwate Prefecture Inside Hitachi Media Electronics Co., Ltd. (72) Inventor Masayoshi Watanabe 1 Kitano, Masaki Character, Mizusawa City, Iwate Prefecture 5D117 AA02 BB03 KK08 5D118 AA06 BA01 DC03 EA02 FA27 FA29 FB12

Claims (4)

[Claims] 1. An objective lens for recording or reproducing information on or from a disk, a bobbin holding the objective lens, a focusing coil for generating a force for driving the bobbin in a focusing direction, and the bobbin in a tracking direction. A tracking coil for generating a driving force for driving the magnetic head, a magnetic circuit for generating a magnetic flux acting on the focusing coil and the tracking coil, a support member for supporting the bobbin at one end, and a holder for supporting the other end of the support member In a state where the objective lens is located at a predetermined working distance from the disk, the support center of the support member in the holder is positioned relative to the support center of the support member in the bobbin. Note that the lens is located away from the disc in the optical axis direction of the lens. An objective lens driving device and an optical pickup or an optical information recording reproducing apparatus equipped with it to. 2. A straight line connecting the support center of the support member in the holder and the support center of the support member in the bobbin, when the objective lens is located at a predetermined working distance from the disk. 2. The objective lens according to claim 1, wherein the objective lens is inclined at a predetermined angle with respect to a plane parallel to the disk, and a moving direction of the hobbin in a focusing direction is a direction perpendicular to the straight line. A driving device and an optical pickup or an optical information recording / reproducing device equipped with the driving device. 3. An optical axis of the objective lens is substantially perpendicular to the disk, and a surface on which a line element for generating a driving force of the focusing coil and the tracking coil is formed has an optical axis of the objective lens. A predetermined angle with respect to the direction, the predetermined angle is a straight line connecting the support center of the support member in the holder and the support center of the support member in the bobbin, the objective lens is 3. The objective lens driving device according to claim 1, wherein the tilt angle with respect to a plane parallel to the disk substantially coincides with the objective lens driving device while being located at a predetermined working distance from the disk. Optical pickup or optical information recording / reproducing device. 4. The direction of a magnetic flux generated by the magnetic circuit is:
Perpendicular to the plane formed by the wire element that generates the driving force of the focusing coil and the tracking coil,
The direction of the magnetic flux is parallel to a straight line connecting the support center of the support member in the holder and the support center of the support member in the bobbin. And an optical pickup or an optical information recording / reproducing apparatus equipped with the objective lens driving apparatus.