JPH11134687A - Objective lens drive unit and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens drive unit, capable of easily correcting the deviation of a proper angle between the optical axis of an objective lens and an optical disk and without impairing reliability even when it is repeatedly operated, and an optical disk device utilizing such the objective lens drive unit. SOLUTION: This objective lens drive unit is provided with focusing coils 42a-42d, arranged on the side of a fixed part of a movable part in which an objective lens 11 is arranged, moving the movable part in the focusing direction by interacting with a driving magnet in making a current flow through it and inclining the movable part in the directions of radial skew and tangential skew corresponding to a skewing amount detected by a skew sensor, and tracking coils 43a, 43b arranged on the side of the fixed part and moving the movable part in the tracking direction by interacting with the driving magnet when making a current flow through it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a driving device of an objective lens which transmits light when information is recorded on or reproduced from an information surface of an optical disk by using light in an optical disk device.

[0002]

2. Description of the Related Art Generally, an optical disk apparatus is optically designed so that when laser light emitted from an optical pickup is perpendicularly incident on a disk surface, aberration is not generated in a focused spot as much as possible. However, in an actual optical disk device, an angle shift phenomenon (hereinafter, referred to as “skew”) between an incident beam and a disk surface during signal recording / reproduction due to shaft runout during rotation of the turntable and warpage of the optical disk alone. Occurs. The higher the density of a signal recorded on an optical disc, the more adversely the coma caused by the skew affects the reading and writing of signals. Therefore, when the density of an optical disc is increased, the disc skew is reduced, or It is necessary to correct optically by the method.

[0003]

In a conventional optical disk apparatus, for example, an optical disk apparatus such as a laser disk having a large disk diameter and a large disk skew, a mechanism as shown in FIG. 14 has been proposed. . In this structure, when a disk skew angle θ occurs, the optical pickup 1 is rotated by an angle θ about a rotation axis 4 on a base 3 of the optical pickup mounted slidably on the mechanical deck 2. The laser beam is made to be perpendicularly incident on the disk surface 5.
However, in the structure of FIG. 14, the large optical pickup 1 has to be tilted as a whole, so that the power consumption is large and it is not easy to tilt at high speed, so that the AC component of the skew synchronized with the rotation of the laser disk (optical disk) It is difficult to compensate for the time variation in which the warpage occurs every rotation.

To solve such a problem, FIGS.
The following objective lens driving device has also been proposed. 15 and 16, the objective lens driving device 10 includes:
An objective lens 11, a bobbin (movable part) 12, a plurality of focus coils 13a, 13b, 13c and 13d,
Tracking coils 14a and 14b, base (fixed portion) 15, four elastic support members 16, tangential skew sensor 17, radial skew sensor 1
8 and a magnet 19.

[0005] The bobbin 12, which is the movable portion, is made of, for example, plastic or the like, and has a rectangular shape as seen in FIG. The objective lens 11 is mounted at the center of the bobbin 12 as viewed in FIG.

The above four focus coils 13a to 13a
3d are arranged at substantially four corners on the upper surface of the bobbin 12 in FIG. These focus coils 13a to 13d are energized so that the bobbin 12
And a drive coil for linearly moving the objective lens 11 in the focus direction FCS or tilting the bobbin 12 and the objective lens 11 in the radial skew direction RSD and the tangential skew direction TSD.

The two tracking coils 14a, 1
4b are attached to the short sides of the bobbin 12, respectively. The tracking coils 14a and 14b are drive coils for linearly moving the bobbin 12 and the objective lens 11 along the tracking direction TRK when energized.

The four elastic support members 16 are provided on the bobbin 1
2 and the base 15. The four elastic support members 16 are arranged symmetrically with respect to the optical axis OPL of the objective lens 11 of the bobbin 12.

The tangential skew sensor 17
The radial skew sensor 18 is provided substantially along the center axis CLL of the bobbin 12 in the plan view of FIG.
a, 13c. Tangential skew sensor 17 and radial skew sensor 1
Reference numeral 8 denotes a sensor for detecting a relative angle between the objective lens 11 and the disk surface of the optical disk.

The magnet 19 is magnetized in the track direction of the optical disk, and adjacent magnets are magnetized in opposite polarities as shown in FIG. These magnets 19 are provided with the focus coils 13a to 13d and the tracking coil 1 described above.
By applying a magnetic field to the track coils 4a and 14b in the track direction, the focus coils 13a through 13
d generates a driving force in the focus direction perpendicular to the disk surface, and the tracking coils 14a and 14b generate a driving force in the tracking direction.

[0011] The objective lens driving device 10 having such a configuration.
According to the method, the bobbin 12 and the objective lens 11, which are movable portions, are moved in the focusing direction by supplying the same drive current to each of the focus coils 13a to 13d. Further, each of the tracking coils 14a and 14
By supplying a drive current to b, the bobbin 12 and the objective lens 11, which are movable parts, are moved in the tracking direction.

When the tangential skew sensor 17 and the radial skew sensor 18 detect a relative angle (skew angle) θ between the objective lens 11 and the disk surface of the optical disk, the focus coils 13a to 13a are set as follows. By controlling the drive current flowing through 13d, skew servo is performed by a so-called tilting operation to correct the skew. That is, when the tangential skew occurs, the drive current of the focus coils 13a and 13b among the focus coils 13a to 13d is changed to the focus coil 13a.
By changing the drive currents c and 13d according to the tangential skew angle, a tangential skew servo is performed, whereby the tangential skew is corrected. When the radial skew occurs, the focus coil 1 of the focus coils 13a to 13d is used.
The drive current of 3a and 13c is supplied to the focus coil 13b
And 13d are changed in accordance with the radial skew angle, thereby performing a radial skew servo, thereby correcting the radial skew.

Thus, the movable part during the skew servo includes the objective lens 11, the bobbin 12, and the driving coils 13a.
To 13d, 14a and 14b, and each skew sensor 1
Since only 8 and 19 are used, the power required for the skew servo is smaller than that of the structure in which the entire optical pickup is rocked as shown in FIG. AC included in skew
Correction of components can be performed appropriately.

However, in the objective lens driving device 10 shown in FIGS. 15 and 16, each driving coil, that is, the focus coils 13a to 13d, the tracking coils 14a and 14b, and the skew sensors 17, 18
Since the wiring to the movable portion is routed from the fixed portion to the movable portion, the structure becomes complicated. For example, in the case of an objective lens driving device in which the objective lens is tilted and controlled in the tangential skew direction and the radial skew direction, at least three focus coils for generating a driving force so as to drive the movable portion in a direction perpendicular to the disk surface are provided. And at least one tracking coil for generating a driving force so as to drive the movable portion in the radial direction of the disk, and six to ten wires to a skew sensor for detecting disk skew are required. is there. For this reason, in an objective lens driving device of a type in which only the objective lens is tilted and controlled, since both the driving coil and the skew sensor are arranged in the movable portion, the structure becomes complicated and the assembly becomes complicated. As a result, the component cost and the assembly cost are increased, and since there are many wires to the movable portion, if the device is repeatedly operated, the wire portion may be damaged, and the reliability particularly at the wire portion may be impaired. There was a problem.

In view of the above, the present invention can easily correct the deviation of the optical axis of the objective lens from the proper angle with the optical disk, and the reliability may be impaired even if the operation is repeated. It is an object of the present invention to provide an objective lens driving device and an optical disk device using such an objective lens driving device.

[0016]

SUMMARY OF THE INVENTION According to the present invention, there is provided an objective lens for transmitting light when recording and / or reproducing information on a signal recording surface of an optical disk of an optical disk device by using the light. A movable portion for supporting the objective lens, a driving magnet attached to the movable portion, and a skew sensor attached to the movable portion for detecting a relative inclination (skew amount) between the optical disc and the objective lens; An elastic support member that supports the movable portion so as to be movable in two axial directions with respect to the fixed portion, and is disposed on the fixed portion side, and interacts with the driving magnet by energization to focus the movable portion. To move the movable part in the radial skew direction and the tangential skew direction in accordance with the skew amount detected by the skew sensor. And yl is disposed on the fixed portion side,
By energization, it interacts with the driving magnet,
This is achieved by an objective lens driving device including a tracking coil that moves a movable portion in a tracking direction.

According to the above arrangement, in the objective lens driving device for performing the focusing and tracking of the objective lens and the tilt for the skew correction, each drive coil, that is, the focus coil and the tracking coil are disposed on the fixed portion side. Since the driving magnet is attached to the movable portion, the wiring for these driving coils does not need to be routed to the movable portion. For this reason, only the wiring to the skew sensor is required for the movable part, so that the wiring to the movable part is smaller than that of a conventional objective lens driving device having a driving coil disposed in the movable part. The process is simplified, component and assembly costs are reduced, and the reliability of the wiring is improved.

When the core material and the support member of the focus coil and the tracking coil are made of a non-magnetic material, the movable portion provided with the driving magnet can prevent the magnetic field from being changed by something other than the driving coil. Since it is not received, more accurate focusing servo, tracking servo and skew servo of the objective lens are performed.

In the case where the focus coil and the tracking coil are arranged so as not to overlap with each other in the direction of the line of magnetic force, all the driving coils are arranged in the vicinity of a magnet having a stronger magnetic field. Become.

When the driving magnets adjacent to each other on the same side of the objective lens have opposite polarities, the magnetic flux closes between the adjacent magnets, and the magnetic flux near the magnets becomes slightly stronger. Therefore, for example, when the present objective lens driving device is applied to a magnetic field modulation type magneto-optical disk device, even if the distance between the laser spot focused by the objective lens and the magnet is shortened, the influence of the leakage magnetic field is not affected. It will be eliminated as much as possible. In addition, a driving magnet arranged at a symmetric position with respect to the objective lens,
If they are arranged so that they have opposite polarities,
Since the component parallel to the optical disk is dominant in the magnetic flux penetrating the vicinity of the objective lens, the effect of the leakage magnetic flux on the magnetic field modulation type magneto-optical disk that performs writing using a vertical magnetic field is reduced. become.

When the above-mentioned focus coil and tracking coil are attached to a printed circuit board provided with a coil wiring provided in a fixed portion, directly or via a coil fixing and positioning member, each drive coil is provided with a drive coil. Wiring to the coil is simplified, and assembly is performed easily and in a short time.

The skew sensor is mounted on a printed circuit board mounted on a movable portion, and power supply to the skew sensor and transmission of a detection signal from the skew sensor are performed by terminals provided on the printed circuit board. When the connection is performed via the skew sensor, the wiring to the skew sensor is similarly simplified, and the assembly is performed easily and in a short time.

The supply of power to the skew sensor and the transmission of a detection signal from the skew sensor are performed via the elastic support member, that is, the elastic support member is made of a conductive material, and Supply of power to the sensor and transmission of the detection signal from the skew sensor,
When performed through the conductive elastic support member itself, or the elastic support member has a wiring pattern on its surface, and supply of power to the skew sensor and transmission of a detection signal from the skew sensor are When the wiring is performed via the wiring pattern on the elastic support member, the structure is further simplified and the cost is reduced by using the elastic support member as wiring to the skew sensor.

A printed circuit board is disposed on the movable section side or the fixed section side, and one end of the elastic supporting member is soldered to the printed board via a positioning member mounted on the printed board or directly. Or a printed circuit board is disposed on the movable section side or the fixed section side, and one end of the wiring pattern of the elastic support member is directly soldered to a predetermined terminal section on the printed board. In such a case, the structure is further simplified and the cost is reduced.

[0025]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows an example of an optical disk device provided with the objective lens driving device of the present invention. The optical disk device 20 in FIG. 1 includes a drive unit 30 for the optical disk D, an objective lens driving device 40, a reproduction optical system 50, and the like.
The drive unit 30 includes a chucking unit 31 and a motor 32. The optical disk D can be detachably attached to the chucking unit 31 by, for example, a magnetic force. The motor 32 is constituted by, for example, a spindle motor whose rotation can be controlled.
And the optical disk D can be continuously rotated.

The objective lens driving device 40 includes the objective lens 1
1 is a device for moving the optical disk 1 with respect to the disk surface DP of the optical disk D. A reproduction optical system 50 is arranged near the objective lens driving device 40. The reproduction optical system 50 includes an optical system having a function of not only reproducing an information signal of the optical disk D but also recording an information signal on a disk surface DP which is a recording surface of the information signal. The reproduction optical system 50 is an optical system that reproduces information signals recorded on the disk surface DP of the optical disk D. The reproduction optical system 50 includes a laser diode 51, a collimator lens 52, a grating 53, and a λ / 2 plate (1 /
A two-wave plate) 54, a polarizing beam splitter 55, a λ / 2 plate 56, a condenser lens 57, a cylindrical lens and a concave lens 58,
An eight-segment photodetector 59, a front monitor photodetector 60, a λ / 4 plate 61 and the like are provided.

The laser diode 51 is, for example, 650 n
The laser beam L having a wavelength of m is generated. The laser beam L is collimated by a collimator lens 52, passes through a grating 53 and a λ / 2 plate 54, and reaches a polarization beam splitter 55. The polarization beam splitter 55 transmits a part of the laser light L to the front monitor photodetector 6.
0 and the rest of the laser light L is guided to the objective lens 11 side. The front monitor photo detector 60
This is a photodetector for monitoring the output of the laser diode 51.

The objective lens 11 focuses the laser light L on the recording surface DP of the optical disk D for recording information signals. The objective lens 11 may have any function as long as it has a lens function for forming the spot SP of the laser beam L in FIG. 1 on the disk surface DP, and may be a convex optical lens made of a glass material such as glass, a plastic lens, or the like. And a hologram element having a light focusing function. The return light from the disk surface DP passes through the λ / 4 plate 61, is reflected by the polarization beam splitter 55, passes through the λ / 2 plate 56, and converges on the condenser lens 5.
The light is condensed at 7 and further condensed by a cylindrical lens and a concave lens 58, and is guided to an 8-part photodetector 59. 8-part photodetector 59
FIG. 5 shows an example of pattern arrangement. The photodetector 59 includes detectors 59a to 59h. The detectors 59a to 59d have a square shape, and the detectors 59e to 59h have a rectangular shape.

Next, the structure of the objective lens driving device 40 shown in FIG. 1 will be described in detail with reference to FIGS. FIG.
FIG. 3 is a side view showing the structure of the objective lens driving device 40 of FIG. 1 in more detail, and FIG. 3 is a plan view of the driving device 40. The objective lens driving device 40 includes an objective lens 11, a movable part 41, a plurality of focus coils 42a, 42b,
42c, 42d and tracking coils 43a, 43b
, A base (fixed portion) 44 and four elastic support members 45
, A tangential skew sensor 46, a radial skew sensor 47, and a magnet 48. The movable portion 41 is made of, for example, plastic or the like, and has a rectangular shape as viewed in FIG. The objective lens 11 is mounted at the center of the movable portion 41 as viewed in FIG.

The above four focus coils 42a to 4a
2d is the movable part 41 on the base 44 of FIG.
Are arranged to face almost four corners. Here, each of the focus coils 42a to 42d is wound around a core material 44a made of a non-magnetic material such as copper and attached to the base 44. These focus coils 42a to 42d linearly move the movable portion 41 and the objective lens 11 in the focus direction FCS by energizing, or move the movable portion 41 and the objective lens 11 in the radial skew direction RS.
D is a driving coil for tilting in the tangential skew direction TSD.

The two tracking coils 43a, 4
3b are mounted on the base 44 so as to face the short sides of the movable portion 41, respectively. Here, each of the tracking coils 43a and 43b is wound around a core material 44b made of a non-magnetic material such as copper, and attached to the base 44. The tracking coils 43a and 43b are driving coils for linearly moving the movable section 41 and the objective lens 11 along the tracking direction TRK when energized.

As shown in FIG. 2, the base 44 includes driving coils, that is, the focus coils 42a to 4d.
A hole or a fixing member 44c for positioning and fixing the 2d and tracking coils 43a and 43b is provided. Each coil is arranged on the base 44 so that the plurality of coils do not overlap in the direction of the magnetic flux by the magnet described later, so that each coil is arranged near the magnet facing the coil. Even in an open magnetic circuit, each coil is disposed in a relatively strong magnetic flux. Further, the base 44 is composed of a printed board 44d made of, for example, glass epoxy resin, and is reinforced by a reinforcing plate 44e made of a nonmagnetic material such as stainless steel and adhered to a lower surface thereof. Accordingly, the magnet 48 on the movable portion 41 can always obtain a driving force substantially proportional to the current supplied to the driving coil without being affected by other magnetic materials. Further, a hole HL is formed in an intermediate portion of the base 44 in FIG. 2, and the hole HL allows the laser beam L coming from the polarization beam splitter 55 to pass therethrough as shown in FIG.
The return light from the disk surface DP is converted into a polarization beam splitter 5.
It is a hole for passing through the 5 side.

On the other hand, the magnet 48 is provided with the focus coils 42a to 42d and the tracking coils 43a and 43d mounted on the base 44.
At a position symmetrical with respect to the position of the objective lens 11 so as to face 3b, a total of six magnets, three magnets on one side,
Each is attached to the side surface of the movable part 41. Each of the magnets 48 is arranged such that, of the three magnets arranged on one side, the center magnet has the opposite polarity to the magnets on both sides. As a result, FIG.
As shown in FIG. 2, since the magnetic flux from one magnet goes to the adjacent magnet, the objective lens 11
Is extremely small. The magnets 48 are arranged such that the magnets located at symmetrical positions with respect to the objective lens 11 have opposite polarities when viewed from the objective lens 11. Thereby, the objective lens 11
The magnetic flux penetrating through the optical disk D as shown in FIG.
Since the component parallel to the disk surface DP becomes dominant, the effect of the leakage magnetic flux is remarkably reduced particularly in a magnetic field modulation type magneto-optical disk device that performs writing using a vertical magnetic field. In the prototype example, the vertical magnetic field at the position of the objective lens 11 is 3 compared with the conventional maximum of 40 Oe.
Oe could be reduced to below.

The four elastic supporting members 45 are movable
It is provided between the base 1 and the base 44 and elastically supports the movable portion 41 with respect to the base 44. These elastic support members 45 are formed, for example, by molding a thin plate made of resin into a substantially cylindrical shape. The four elastic support members 45 are connected to the optical axis OPL of the objective lens 11 of the movable section 41.
And the upper mounting portion of the elastic support member 45 is set at the same height H as the principal point of the objective lens 11, that is, at the same height H with respect to the upper surface of the base 44. As shown in FIG. 9, each of the elastic support members 45 has two wiring patterns 45a and 45b, and the ends thereof have solder lands 45c and 45b.
45d are formed.

The tangential skew sensor 46
The radial skew sensor 47 is provided substantially along the center axis CLL of the movable portion 41 in the plan view of FIG.
a, 43b. Radial skew sensor 46 and tangential skew sensor 47
Is the objective lens 11 and the disk surface DP of the optical disk D
(See FIG. 1).

Next, the structures of the tangential skew sensor 46 and the radial skew sensor 47 shown in FIG. 3 will be described. In FIG. 3, assuming that the optical disk D is, for example, a disk having a diameter of 120 mm (for example, a compact disk or a disk in which two disks are bonded together for high-density recording), for example, the radius of the optical disk D The skew sensors 46 and 47 are arranged on the movable part 41 such that the object lens 11 and the two sensors are located on the same track in the vicinity of 40 mm.
That is, the skew sensors 46 and 47 are arranged on the movable portion 41 so as to be offset toward the center of the optical disc D with respect to the objective lens 11.

FIG. 6 shows an example of the arrangement of detectors of the tangential skew sensor 46, and FIG. 7 shows an example of the arrangement of detectors of the radial skew sensor 47.
In FIG. 6, the tangential skew sensor 46
Has an LED (light emitting element) 46a as a light generating means and two phototransistors 46b and 46c. The phototransistors 46b and 46c are light receiving means.
These LEDs 46a and phototransistors 46b, 4
6c is a lens and optical filter F as shown in FIG.
Covered by T. The tangential skew sensor 46 detects a relative angle between the objective lens 11 and the disk surface DP of the optical disk D in the tangential skew direction TSD as shown in FIG.

The radial skew sensor 47 shown in FIG. 7 includes an LED 47a as light generating means and phototransistors 47b and 47c as light receiving means. These LEDs
As shown in FIG. 8, the phototransistor 47a and the phototransistors 47b and 47c are covered with a lens and an optical filter FT. The radial skew sensor 47 is provided between the objective lens 11 and the disk surface D of the optical disk D as shown in FIG.
This detects the relative angle with respect to the radial skew direction RSD. 8 and the optical filter F
T is made of, for example, a transparent plastic, and transmits light generated by the LEDs 46a and 47a in FIGS. 6 and 7, but shields laser light L generated by the laser diode 51 of the reproduction optical system 50 in FIG. I do. That is, for example, the lens and the optical filter FT have a property of blocking the entry of light having a wavelength of 650 nm, but transmitting light having a wavelength of 950 nm.

Next, the eight-divided photodetector 5 shown in FIG.
9, the tangential skew sensor 46 in FIG. 6, the radial skew sensor 47 in FIG. 7, the focus coils 42a to 42d and the tracking coil 43 in FIG.
The drive circuit 70 composed of a, 43b, etc. will be described with reference to FIG.

As described above, the driving circuit 70 of FIG.
The connection relationship among an eight-divided photodetector 59, a radial skew sensor 47, a tangential skew sensor 46, four focus coils 42a to 42d, and two tracking coils 43a and 43b is shown.
In FIG. 4, the photodetector 59 includes a phase compensator 7.
1 and the gain adjuster 72 are connected to the two tracking coils 43a and 43b. The photo detector 59 is connected to the four focus coils 42a to 42d via the phase compensator 73 and the gain adjuster 74. The radial skew sensor 47 passes through a phase compensator 75, a gain adjuster 76, and an inverter 77,
It is connected to two focus coils 42b and 42d. The radial skew sensor 47 is connected to two focus coils 42a and 42c via a phase compensator 75 and a gain adjuster 76. The tangential skew sensor 46 is connected to the focus coil 42 via a phase compensator 78, a gain adjuster 79, and an inverter 80.
c, 42d. The tangential skew sensor 46 is connected to the focus coils 42a and 42b via a phase compensator 78 and a gain adjuster 79.

Here, these two skew sensors 4
As shown in FIG. 10, the components 6 and 47 are mounted on a mount substrate 41 a provided on the movable portion 41. The mount substrate 41a is provided with movable lands 45c, 45b of the wiring patterns 45a, 45b of the elastic support member 45 described above.
d is soldered. On the other hand, as shown in FIG. 11, a driver circuit board 44f for supplying current to each drive coil and a skew sensor 4 are provided on the base 44.
A skew detection circuit board 44g for processing the 6, 47 detection signals is connected. Each drive coil is connected to the driver circuit board 44f via a coil wiring formed on a printed board 44d of the base 44. Further, the fixed lands 45c and 45d of the elastic support member 45 are connected to the printed circuit board 4 of the base 44.
It is soldered to the wiring for the skew sensor on 4d.
Thus, the skew sensors 46 and 47 are connected to the skew detection circuit board 44g via the wiring patterns 45a and 45b of the elastic support member 45.

In the reproducing optical system 50 shown in FIG. 1, the photodetector 59 receives the return light from the disk surface DP,
After the focus error signal FES is phase-compensated by the phase compensator 73 from the detectors 59a, 59b, 59c, and 59d in FIG. 4 and the gain is adjusted by the gain adjuster 74, the four focus coils 42a to 42d are Drive current is sent in the same phase. The detectors 59e, 59f, 59h, 59g of the photo detector 59 of FIG.
, The tracking error signal TRS is sent to the phase compensator 71. After the tracking error signal TRS is phase-compensated by the phase compensator 71 and the gain is adjusted by the gain adjuster 72, the drive current of the same phase is output from the gain adjuster 72 to the two tracking coils 43a and 43b.
Sent to

The radial skew error signal RSE obtained from the radial skew sensor 47 shown in FIG. 4 is sent to a phase compensator 75 for phase compensation and a gain adjuster 76.
The gain is adjusted by. A drive current of the same phase is sent from the gain adjuster 76 to the two focus coils 42a and 42c, and a drive current of the opposite phase is sent from the inverter 77 to the remaining two focus coils 42b and 42d. Sent. The tangential skew error signal TSE obtained from the tangential skew sensor 46 in FIG. 4 is phase-compensated by the phase compensator 78 and gain is adjusted by the gain adjuster 79. Thereafter, a drive current having the same phase is sent from the gain adjuster 79 to the two focus coils 42a and 42b, and a drive current having the opposite phase is sent from the inverter 80 to the remaining two focus coils 42c and 42d. Electric current is sent.

In FIG. 2, the center of gravity of the movable portion 41, the principal point of the objective lens 11, and the mounting height H of the elastic support member 45 are substantially the same. Thereby, when the same phase driving current for the focus servo is applied to the focus coils 42a to 42d in FIG. 4, the movable portion 41 never disturbs the posture in the focus direction FCS (to the disk surface DP in FIG. 1). It is driven only in the direction of approaching or moving away, in the direction perpendicular to the disk surface DP. That is, the four elastic support members 45 and the four focus coils 42a to 4a
Since 2d is point-symmetrical with respect to the principal point of the lens 11, the movable part 41 does not generate a lateral swing (a swing in the tracking direction TRK direction or the track direction TD direction), and the objective lens 11 focuses. Servo operation can be performed. On the other hand, the tracking coils 43a, 4 in FIG.
Even when a tracking servo current of the same phase is applied to 3b, the movable section 41 can move linearly without disturbing the attitude in the tracking direction TRK (radial direction) of FIG.

Next, when radial skew servo is applied to the movable part 41 and the objective lens 11, the position of the principal point of the objective lens 11, the center of gravity of the movable part 41, and the mounting height H of the elastic support member 45 are determined. Since they substantially coincide with each other, only a moment force having the position of the center of gravity of the movable portion 41 as the center of rotation is generated as the resultant force of the driving force. That is, when a radial skew servo current is applied to the four focus coils 42a to 42d based on the radial skew signal RSE in FIG. 4, the movable portion 41 never linearly moves, and only the radial skew direction RSD in FIG. Will be tilted. The same applies to the case where the tangential skew servo is applied to the movable part 41 and the objective lens 11, and the position of the principal point of the objective lens 11, the center of gravity of the movable part 41, and the mounting height H of the elastic support member 45 are substantially the same. Match,
Since the resultant force of the driving force is also only the moment force having the center of gravity as the center of rotation, when the tangential skew servo current is applied to the focus coils 42a to 42d, the movable portion 41 never moves linearly in FIG. It is tilted only in the tangential skew direction TSD.

When the radial skew servo is applied to the objective lens 11 as described above, the focus coil 42 is used based on the radial skew error signal RSE of FIG.
Radial skew servo currents of the same phase are given to the a and c, and the remaining two focus coils 42 b and 42 c
Since a radial skew servo current having an opposite phase is applied to d, the movable portion 41 tilts only in the radial skew direction RSD. On the other hand, when tangential skew servo is applied to the objective lens 11, a tangential skew servo current having the same phase is applied to the two focus coils 42a and 42b based on the tangential skew error signal TSE of FIG. Since the other two focus coils 42c and 42d receive tangential skew servo currents of opposite phases, the bobbin 5 tilts in the tangential skew direction TSD of FIG.

According to the amount of skew generated on the optical disk D,
The objective lens 11 and the movable part 41 are tilted in the radial skew direction RSD,
Can be tilted to SD. Therefore, the objective lens 1
One coma can be canceled.

Therefore, it is possible to easily correct the deviation of the optical axis OPL of the objective lens 2 of the optical pickup from the proper angle with the optical disk D for writing the accuracy of the mechanism and the warpage of the optical disk as a recording medium. . In addition, mechanical buffering in a total of four directions of focusing, tracking, radial skew, and tangential skew can be reduced as much as possible. Can work. Thereby, the disc surface DP and the optical axis O of the objective lens 2 in FIG.
The skew, which is the deviation of the angle of PL, can be accurately detected with a simple structure.

In this case, the driving coils, ie, the focus coils 42a to 42d and the tracking coil 43
a and 43b are fixedly arranged on a base 44 which is a fixing portion. Therefore, the number of wires for the movable section 41 is greatly reduced, the assembly of the objective lens driving device 20 is easily performed, and the assembly cost is reduced.
The wiring for the movable section 41 is
Since only the wiring for the wirings 6 and 47 is required, the reliability of the wiring is improved. Furthermore, by performing wiring to the skew sensors 46 and 47 using the elastic support member 45 that supports the movable portion 41, the wiring process is simplified.

In the above-described embodiment, the elastic support member 4
5 has the wiring patterns 45a and 45b on its surface, but is not limited thereto, and the elastic support member 45 itself may be formed from a conductive material. In this case, each elastic support member 45 is used as one line.

In the above-described embodiment, an example in which the optical disk apparatus reproduces information recorded on the information surface of the optical disk has been described. However, the present invention is not limited thereto, and the objective lens driving device of the present invention can be applied to a recording / reproducing optical disk device capable of recording and reproducing information on and from an optical disk.

[0053]

As described above, according to the present invention,
In an objective lens driving apparatus for performing focusing and tracking of an objective lens and tilting for skew correction, each driving coil, that is, a focus coil and a tracking coil are disposed on a fixed portion side, and a driving magnet is provided on a movable portion. The wiring for these drive coils does not need to be routed to the movable part. For this reason, only the wiring to the skew sensor is required for the movable part, so that the wiring to the movable part is smaller than that of a conventional objective lens driving device having a driving coil disposed in the movable part. The process is simplified, the cost of parts and assembly is reduced, and the number of wiring portions that are structurally weak is reduced, so that damage due to repeated use is eliminated and reliability is improved. As described above, according to the present invention, the deviation of the optical axis of the objective lens from the appropriate angle with the optical disc can be easily corrected, and the reliability of the objective lens is not impaired even if it is repeatedly operated. It is possible to provide a driving device and an optical disk device using such an objective lens driving device.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an optical disk device including a driving device for an objective lens according to the present invention.

FIG. 2 is a side view showing an embodiment of an objective lens driving device of the optical disc device of FIG. 1;

FIG. 3 is a plan view of the objective lens driving device of FIG. 2;

FIG. 4 is a diagram showing an example of a drive circuit for a focus coil and a tracking coil in FIGS. 2 and 3;

FIG. 5 is a diagram illustrating an example of a photodetector in the reproduction optical system of FIG. 1;

FIG. 6 is a diagram illustrating an example of the tangential skew sensor of FIG. 3;

FIG. 7 is a diagram illustrating an example of the radial skew sensor of FIG. 3;

FIG. 8 is a diagram illustrating an example of an optical filter of the skew sensor of FIGS. 6 and 7;

FIG. 9 is a view showing an example of the elastic support member of FIG. 3;

FIG. 10 is a side view showing the wiring of the drive coil and the skew sensor of FIG. 3;

FIG. 11 is a plan view showing wiring of a drive coil and a skew sensor of FIG. 3;

FIG. 12 is a plan view showing a magnetic flux generated by the magnet of FIG. 3;

FIG. 13 is a side view showing a magnetic flux by the magnet of FIG. 3;

FIG. 14 is a diagram showing an example of a skew angle θ of a disk in a conventional optical disk device.

FIG. 15 is a side view showing an example of a conventional objective lens driving device.

16 is a plan view of the objective lens driving device of FIG.

[Explanation of symbols]

D: optical disk, FCS: focus direction, F
T: lens and optical filter, H: mounting height of the elastic support member to the movable part, L: laser light (light), OPL: optical axis of objective lens, RSD ...
Radial skew direction, TRK: tracking direction, TSD: tangential skew direction, 11
... Objective lens, 40 ... Objective lens driving device, 4
1 movable part, 42a to 42d focus coil, 43a, 43b tracking coil, 44
... Base, 45 ... Elastic support member, 46 ... Tangential skew sensor (skew sensor), 4
7 ... radial skew sensor (skew sensor),
48 ... magnet.

Claims (12)

[Claims] 1. An objective lens for transmitting light when recording and / or reproducing information on a signal recording surface of an optical disk of an optical disk device by using light, a movable portion supporting the objective lens, and an attachment to the movable portion. A driving magnet, a skew sensor attached to the movable portion, for detecting a relative inclination (skew amount) between the optical disk and the objective lens, and a biaxial direction with respect to the fixed portion. An elastic support member movably supporting the skew amount, the skew amount being arranged on the fixed portion side, interacting with the driving magnet by energization, moving the movable portion in the focus direction, and being detected by the skew sensor; A focus coil for tilting the movable portion in the radial skew direction and the tangential skew direction in accordance with And a tracking coil that interacts with the driving magnet to move a movable part in a tracking direction. 2. The objective lens driving device according to claim 1, wherein the core material and the support member of the focus coil and the tracking coil are made of a non-magnetic material. 3. The objective lens driving device according to claim 2, wherein the focus coil and the tracking coil are arranged so as not to overlap with each other in a direction of a magnetic field line. 4. The driving magnet, wherein magnets adjacent to each other on the same side with respect to the objective lens have opposite polarities, and magnets disposed symmetrically with respect to the objective lens have opposite polarities. 3. The objective lens driving device according to claim 2, wherein the objective lens driving device is arranged as described above. 5. The method according to claim 1, wherein the focus coil and the tracking coil are attached directly or via a coil fixing and positioning member to a printed circuit board provided with a coil wiring provided in a fixing portion. The objective lens driving device according to claim 1. 6. The skew sensor is mounted on a printed circuit board attached to a movable part, and power supply to the skew sensor and transmission of a detection signal from the skew sensor are provided on the printed circuit board. 2. The objective lens driving device according to claim 1, wherein the driving is performed via a terminal. 7. The objective lens driving device according to claim 1, wherein power supply to the skew sensor and transmission of a detection signal from the skew sensor are performed via the elastic support member. 8. The elastic support member is made of a conductive material, and power supply to the skew sensor and transmission of a detection signal from the skew sensor are performed via the conductive elastic support member itself. The objective lens driving device according to claim 7, wherein 9. A printed circuit board is provided on a movable section side or a fixed section side, and one end of the elastic support member is connected to the printed board directly or via a positioning member mounted on the printed board. 9. The objective lens driving device according to claim 8, wherein the objective lens driving device is soldered. 10. The elastic support member has a wiring pattern on a surface thereof, and power supply to the skew sensor and transmission of a detection signal from the skew sensor are performed via the wiring pattern on the elastic support member. 8. The objective lens driving device according to claim 7, wherein the driving is performed. 11. A printed circuit board is provided on a movable portion side or a fixed portion side, and one end of a wiring pattern of the elastic support member is directly soldered to a predetermined terminal portion on the printed circuit board. The objective lens driving device according to claim 10, wherein: 12. A means for rotationally driving an optical disk, an objective lens for transmitting light when recording and / or reproducing information on a signal recording surface of the optical disk using light, and a focusing direction and a tracking direction for the objective lens. And a reproducing optical system for detecting return light reflected from the signal recording surface of the optical disc, the movable device supporting the objective lens. A driving magnet attached to the movable portion; a skew sensor attached to the movable portion for detecting a relative inclination (skew amount) between the optical disc and the objective lens; An elastic support member that is movably supported in two axial directions, and is disposed on the fixed portion side, and interacts with the driving magnet when energized, A focus coil that moves the moving part in the focus direction and tilts the movable part in the radial skew direction and the tangential skew direction in accordance with the skew amount detected by the skew sensor; And a tracking coil that interacts with the driving magnet to move a movable portion in a tracking direction.