JPS6254843A - Multidimensional driver for objective lens - Google Patents

Abstract

PURPOSE:To shift multidirectionally an objective-lens supporter cylinder without causing it to incline by using cylindrical coils and flat coils provided on the peripheral surface of an outer cylinder. CONSTITUTION:The objective lens 1 supported by the objective-lens supporter cylinder 3 is driven in Z-direction by the electro-magnetic force generated by a focus adjusting coil 28 provided around the outer peripheral part 5a of the outer cylinder 5 because said cylinder 3 is supported by an intermediate body 10 freely slidablly. The flange part 10a of the body 10 energized downward by a damper 18 contacts the projection part 16d of a magnetic body 16 while the body 10 is supported slidablly on the plane X-Y, and therefore, the objective lens 1 is driven in the directions of X and Y by the electro-magnetic force generated by tacking adjusting coils 38a and 38b, and tangential adjusting coils 38c and 38d which are the flat coils provided on the outer peripheral surface 5a of the outer cylinder 5. In such way, the objective lens 1 is smoothly driven in three dimensions of axes X, Y, and Z without being inclined.

Description

Detailed Description of the Invention Object of the Invention [Industrial Field of Application] The present invention relates to a multidimensional driving device for an objective lens, and more specifically, the present invention relates to a multidimensional driving device for an objective lens, and more specifically, for controlling the position of an objective lens that faces an optical disk and forms an optical path for optical reading. The present invention relates to a multidimensional drive device for an objective lens that drives multidimensionally.

[Prior Art] In order to read information recorded on a rotating optical disk, it is necessary to accurately focus the light from a laser or other source used for reading onto the position on the optical disk where the information is recorded using an objective lens. . To control the position of this focal point,
Basically, there is a vertical focus servo that keeps the focus on the information recording surface as the optical disc moves up and down, a tracking servo in the radial direction of the optical disc that follows the track on which information is recorded, and a rotation of the optical disc. There are three types of servo: a tangential servo in the tangential direction of the optical disk that cancels out time axis fluctuations caused by unevenness, eccentricity, etc.

Among these servo systems, tracking and tangential servos can also be realized by controlling the angle of a mirror installed in the optical reading optical path, but for the purpose of simplifying and downsizing the device, the objective lens is A multidimensional drive device for an objective lens that drives in three directions has been proposed.

FIG. 3 is a partially cutaway perspective view showing an example of such an objective lens device, and as shown in the figure, an objective lens holding cylinder B holding an objective lens A is attached to a housing C with two upper and lower elastic support members D1. ．． Supported by D2. The objective lens holding cylinder B has a focusing coil F that drives it in the Z-axis (up and down) direction, a set of tracking coils G that drives it in the X-axis (radial) direction, and a set of tracking coils G that drives it in the Y-axis (tangential) direction.
A set of tangential coils H is provided, and the evidence body C is provided with magnetic members Jl, J2 and 1. 2 is provided for. Therefore, this objective lens device can multidimensionally control the position of the objective lens holding cylinder according to the current flowing through each coil.

[Problems to be Solved by the Invention] In such a conventional objective lens device, the objective lens holding cylinder B is attached to the elastic support member D1. The objective lens holding cylinder may be tilted because it is suspended by D2. In this case,
The shape of the spot of light focused by the objective lens becomes an ellipse, and the S/
There was a problem in that the N ratio deteriorated.

The objective lens holding cylinder is displaced by receiving forces of different magnitudes in three-dimensional directions via each of the three sets of coils, but in contrast, the elastic support member D1. D2 receives a reaction force according to its elastic coefficient, etc. For this reason, it is extremely difficult to balance the forces applied to the objective lens holding cylinder B and drive the objective lens without tilting it. This problem is caused by the elastic support member D1. The same applies to the case where D2 is constituted by a spiral leaf spring or the like.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multidimensional driving device for an objective lens that drives the objective lens in multiple dimensions without tilting the objective lens with a simple configuration.

Structure of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following structure as a means for solving the problems. That is, a multidimensional driving device for an objective lens that multidimensionally drives the position of an objective lens that faces an optical disk and forms an optical path for optically reading it with respect to a pedestal that supports the objective lens, The objective lens holding tube that holds the lens is attached approximately to the axial center of a non-magnetic outer tube that has a larger diameter than the objective lens holding tube. The objective lens holding cylinder is slidably supported in the axial direction by a slidably supported sliding member, and the sliding member is elastically supported on the plane by an elastic support member attached to the pedestal. A cylindrical coil for driving the outer cylinder in the axial direction of the objective lens holding cylinder and a coil for driving the outer cylinder in the plane are provided on the circumferential surface of the outer cylinder.
This is the structure of a multidimensional driving device for an objective lens, which is equipped with the above flat coil, and the pedestal is provided with a magnetic member that forms a magnetic path passing through the cylindrical coil and the flat coil.

[Function] The objective lens multidimensional drive device of the present invention having the above configuration receives force in multidimensional directions via a cylindrical coil and one or more flat coils provided on the circumferential surface of the outer cylinder, The objective lens holding cylinder provided approximately at the center of the outer cylinder is multidimensionally displaced. Here, the objective lens holding tube is supported by a sliding member that is slidably supported on a plane perpendicular to the axial direction of the objective lens holding tube, and is also slidable freely in the axial direction of the objective lens holding tube itself. has been done. Therefore, the multidimensional driving device for an objective lens of the present invention works to drive the objective lens holding cylinder in multidimensional directions without causing any inclination φ.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 is a sectional view showing a three-dimensional driving device for an objective lens as an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof.

As shown in the figure, the three-dimensional driving device for the objective lens of the present embodiment includes an outer cylinder 5 in which an objective lens holding cylinder 3 containing an objective lens 1 is attached at its axial center, and an outer cylinder 5 provided on the outer circumferential surface of the outer cylinder 5, which will be described later. a cylindrical intermediate body 10 that slidably houses the objective lens holding cylinder 3, and a donut-shaped magnetic body 14, 16 that is magnetically coupled to the permanent magnet 12 to form a magnetic path.
The main part is a rubber damper 18 having four limbs.

The magnetic body 16 also functions as a pedestal in the objective lens three-dimensional drive device of this embodiment, and has a through hole 16a at its center. Permanent magnets 12 are adhered concentrically on an upward plane 16b perpendicular to the axial direction (hereinafter referred to as the X-axis direction) of the through hole 16a. A magnetic body 14 is also concentrically adhered to the flat surface 12a.Since the inner diameter of the magnetic body 14 is larger than the outer diameter of the opposing portion 16c of the mimagnetic body 16, a gap of a certain width is formed here during assembly. Since the permanent magnet 12 is polarized with an N pole on the upper side and an S pole on the lower side, a magnetic path passing through this gap is formed via the magnetic bodies 14 and 16.

The intermediate body 10 is made of a non-magnetic material, such as synthetic resin, and is accommodated in the through hole 16a of the magnetic body 16. This intermediate body 10 has a protrusion 1. whose collar portion 10a is provided on the upper part of the facing portion 16c of the magnetic body 16. ．． 6d, it is locked by the damper 18. That is, the ring 18a provided at the center of the damper 18 is fitted into the flange portion 10b at the end of the intermediate body 10, and the rings 18b at the tips of the four limbs are fitted into the flange portion 10b provided at the lower surface 16e of the magnetic body 16.
The intermediate body 10 is locked by being fitted into the protrusions 16g of each of the two leg portions 16f. Therefore,
The intermediate body 10 is urged downward by the elastic damper 18, and due to the contact between the collar portion 10a and the protrusion 16d of the magnetic body 16, the intermediate body 10 is tilted in a plane perpendicular to the X-axis direction. It is supported so that it can be moved around without causing any problems. Incidentally, since the surface of the protrusion 16d of the magnetic body 16 is coated with a synthetic resin having a small coefficient of friction, the collar portion 10a smoothly rotates on the protrusion 16d.

When the objective lens holding tube 3 attached to the axial center of the outer tube 5 is accommodated from above inside the above-mentioned intermediate body 10, the outer tube 5
The outer circumferential portion 5a is loosely fitted into the gap between the magnetic bodies 14 and 16 described above. This outer peripheral portion 5a is provided with a coil 8, and the magnetic path described above passes through the coil 8. The coil 8 includes a focus adjustment coil 28 wound in a cylindrical shape along the outer circumference 5a, and a pair of tracking adjustment coils 38a and 38b, which are flat coils attached to the focus adjustment coil 28. A pair of tangential adjustment coils 38c, which are flat coils, are installed at positions perpendicular to this.

There is d. These coils 8 are made of self-bonding wires, are made into a cylindrical shape corresponding to the shape of the outer circumference 5a of the outer cylinder 5 and curved flat corresponding to the shape of the outer circumference 5a of the outer cylinder 5, and are pasted to the outer circumference 5a with adhesive. It is attached.

Since the above-described magnetic path passes through these coils, when a current is passed through the coil 8 by a servo device (not shown), an electromagnetic force is generated in the coil 8. In the case of the focus adjustment coil 28, all the force generated in the coil 28 is in the X-axis direction, and as the objective lens holding cylinder 3 rotates inside the intermediate body 10, the objective lens 1 together with the outer cylinder 5 is moved in the X-axis direction. Drive to. On the other hand, tracking adjustment coils 38a, 3
8b, when a current is passed through it, the forces generated on both sides in the X-axis direction are in the same direction in the X-axis direction, and the forces generated on both sides along the circumferential direction of the outer cylinder 5 are different from each other in the X-axis direction. They turn in opposite directions and cancel each other out. Therefore, due to the electromagnetic force generated in the pair of tracking adjustment coils 38a and 38b, the objective lens 1 together with the outer cylinder 5 and the intermediate body 10
It will be driven in the axial direction. On the other hand, when a current is applied to the tangential adjustment coils 38c and 38d, electromagnetic force is generated on each side of the coils 38c and 38d, similar to the case of the tracking adjustment coils 38a and 38b, and the objective lens 1 is moved to the outer tube 5.
The entire intermediate body 10 can be driven in the Y-axis direction.

Note that the intermediate body 10 has one end connected to the damper 1 as described above.
8, the focus adjustment coil 28° and the tracking adjustment coils 38a and 38b
When the supply of current to the tangential adjustment coils 38c and 38d is cut off, the objective lens 1, along with the outer cylinder 5 and the intermediate body 10, returns to the initial position (the origin on the X, Y, and Z axes).

In this embodiment configured as described above, the objective lens 1 held by the objective lens holding tube 3 is slidably supported by the intermediate body 10, so that the objective lens 1 can be moved outwardly. The flange 10a of the intermediate body 10 and the magnetic body 16 are driven in the Z-axis direction by the electromagnetic force generated in the focus adjustment coil 28 provided on the outer periphery 5a of the cylinder 5, and are urged downward by the damper 18. Since the intermediate body 10 is supported slidably on the X-Y plane by being in contact with the protrusion 16d, the outer circumference 5 of the outer cylinder 5
Tracking adjustment coils 38a, 38b and tangential adjustment coil 3, which are flat coils provided in a.
It is driven in the X-axis and Y-axis directions by electromagnetic force generated at 8c and 38d. Therefore, the objective lens 1 is smoothly driven in the three-dimensional directions of the X-axis, Y-axis, and Z-axis without tilting.

In addition, the three-dimensional drive device for the objective lens of this embodiment uses a donut-shaped permanent magnet 12 and a magnetic body 14°16, and three types of coils are arranged in the magnetic path formed by these, so it is extremely With a simple configuration, it is possible to drive the objective lens 1 in three-dimensional directions.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, a configuration in which an objective lens is driven two-dimensionally using a set of flattened coils, and Of course, it can be implemented in various ways, such as a so-called bobbinless coil configuration in which the surface is formed only of coils.

Effects of the Invention As detailed above, the multidimensional driving device for an objective lens of the present invention has the advantage of being able to drive the objective lens in multiple directions without tilting the objective lens with a simple configuration. It has a great effect. Therefore, when reading an optical disc, it is possible to make the device more compact compared to a conventional configuration using a movable mirror, etc., and it is also possible to focus light onto the optical disc with high precision. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a three-dimensional driving device for an objective lens as an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a configuration of an objective lens device as a conventional technique. It is a partially cutaway perspective view. 1... Objective lens 3... Objective lens holding cylinder 5... Outer cylinder 10... Intermediate body 12...
・Permanent magnet 14.16...Magnetic material 18...
damper

Claims (1)

[Claims] 1. A multidimensional driving device for an objective lens that multidimensionally moves the position of an objective lens that faces an optical disk and forms an optical path for optically reading it with respect to a pedestal that supports the objective lens. an objective lens holding tube that holds the objective lens is attached approximately to the axial center of a non-magnetic outer tube having a larger diameter than the objective lens holding tube; and a plane perpendicular to the axial direction of the objective lens holding tube. The objective lens holding cylinder is slidably supported in the axial direction by a sliding member that is slidably supported on the pedestal, and the sliding member is supported on the plane by an elastic support member that is attached to the pedestal. A cylindrical coil for driving the outer cylinder in the axial direction of the objective lens holding cylinder and one or more flattened coils for driving the outer cylinder in the plane are provided on the circumferential surface of the outer cylinder. a multidimensional driving device for an objective lens, the pedestal being provided with a magnetic member forming a magnetic path passing through the cylindrical coil and the flat coil.