KR100474772B1 - Optical pick-up actuator - Google Patents

Abstract

The present invention discloses an optical pickup actuator capable of automatically correcting a tilt angle generated in a disk according to the operation of a focusing coil. The disclosed invention includes a lens holder for fixedly placing an objective lens capable of focusing a light beam on a data recording surface of an optical disc; First and second permanent magnets disposed on left and right sides of the lens holder to form a magnetic field; A focusing coil wound along a circumference of the lens holder and subjecting the lens holder to a magnetic force in a vertical direction; Disposed on both sides of one side edge of the lens holder facing the first permanent magnet and one side edge of the lens holder facing the second permanent magnet, so as to receive a horizontal magnetic force from the lens holder. One tracking coil; And a first radial coil and a second radial coil which are respectively disposed inside the outer tracking coil of the tracking coils and are electrically connected to the focusing coil .

Description

Optical pick-up actuator {OPTICAL PICK-UP ACTUATOR}

The present invention relates to an optical pickup actuator, and more particularly, to an optical pickup actuator capable of automatically correcting a tilt angle change during focusing operation by mechanical run-out of an optical disc.

Recently, with the rapid development of optical discs, various products of optical pickups for recording / reproducing information of optical discs have been developed. An objective lens driving device is configured together with an optical pickup so that an optical spot that follows the center of a signal track of the optical disk is subjected to the optical vibration of the optical disk and the surface vibration and eccentricity of the optical disk caused by the rotation of the optical disk. Such an objective lens driving apparatus is called an optical pickup actuator and drives the objective lens to perform focusing and tracking operations.

The focusing operation is to drive the objective lens up and down so that the light spot of the light beam from the objective lens falls within the depth of focus in the signal track of the optical disc. The tracking operation is to drive left and right so that the light spot of the light beam from the objective lens follows the center of the signal track of the optical disc.

1 is a view schematically showing the structure of an optical pickup actuator according to the prior art.

As shown in Fig. 1, an objective lens 3 for condensing a light beam from a laser diode light source on an information recording surface of an optical disc, a lens holder 1 in which the objective lens 3 is inserted into an inner diameter, and the lens holder (1) yokes (for preventing the left and right a predetermined distance spaced apart from and disposed on the back of the permanent magnets 6 and the permanent magnets (6) disposed, respectively, leakage of the magnetic flux from the permanent magnet 6 to 7 ) And a tracking coil disposed opposite to the permanent magnets 6 and arranged in a direction perpendicular to the direction in which the focusing coil 4 and the focusing coil 4 are wound around the outer circumference of the lens holder 1. It consists of the coil 5.

The operation of the actuator having the above structure is as follows.

The optical pickup actuator utilizes the force of the magnetic field of the permanent magnets 6 disposed on the left and right of the lens holder 1 on which the objective lens 3 is disposed for the focusing and tracking operation of the objective lens 3. To move up and down, left and right. The driving force of the optical pick-up actuator is applied to the tracking coil 5 and the focusing coil 4 in the magnetic field space formed by the permanent magnet 6 and the yoke 7, and according to Lorentz by Fleming's left hand law. Generated by force.

The objective lens 3 is operated left and right by applying a current to the tracking coil 5, and the objective lens 3 is operated up and down by applying a current to the focusing coil 4. Although not shown in the drawings, reference numeral 10, which is not described, is a damper holder for reducing the resonance peak of the actuator.

2 is a diagram illustrating a mechanism of an optical disk drive for reading data of a disk according to the prior art.

As shown in FIG. 2, the disk 20 fixed by the turntable 22 and the clamper 21 is rotated by a spindle motor 30, and the optical pickup actuator is lowered in the disk 20. The light source is irradiated with light through an objective lens at a predetermined distance to record and reproduce data using the reflected light. In addition, the optical pickup is supported by a deck 24, and the deck 24 is supported by a damper to maintain a stable state against vibration and shock. Although shown in the figure, 100, which is not described, represents a deck base portion.

3A to 3C are diagrams for explaining the correlation between the tilting operation and the focusing operation of the optical pickup actuator according to the run-out and mechanical failure of the disc.

As shown in Fig. 3A, when the disk 20 is rotated in a neutral state, the objective lens fixedly disposed on the lens holder of the actuator constantly irradiates the disk with light. However, as shown in FIG. 3B, when the disk 20 to record / reproduce data is bent upward than the neutral state by mechanical run-out, the objective lens is turned upward by the focusing operation of the actuator. In this case, the tilt angle -θ occurs.

In addition, as shown in FIG. 3C, when the disc 20 to record / reproduce data is bent downward than the neutral state, the objective lens moves downward due to the focusing operation of the actuator, and a tilt angle + θ occurs. to be.

As described above, when the disc 20 is bent at a constant angle (-θ and + θ) in a neutral state, data may not be recorded / reproduced by only focusing and tracking operations in order to record / reproduce accurate data. Therefore, the objective lens portion of the optical pickup actuator should also be inclined by the generated tilt angle, which is called tilt angle correction.

4A and 4B are diagrams for explaining the concept of tilt angle correction of a disc.

As shown in FIG. 4A, when an error in the tilt angle occurs due to mechanical problems such as disc run-out or bending of the disc, as shown in FIG. 4B, separate radial coils are arranged on the optical pickup actuator to provide optical pickup. Demonstrate the concept of calibrating an actuator to have a predetermined slope.

Therefore, a permanent magnet and a current applying coil part are usually provided to form a separate magnetic field for tilt angle correction.

Since the tilt angle can cause errors in data reproduction and recording, it is difficult to record / reproduce accurate data even when the disc is high speed and density, and even small tilt angles are generated. Therefore, the tilt angle correction operation is gradually required in the actuator. Item.

However, the method of correcting the tilt angle by arranging a separate radial drive system should accurately grasp how much the tilt angle should be corrected, and the cost of the system may be increased or the manufacturing burden may be increased by adding a unique radial drive system.

The present invention has been made to solve the above problems of the prior art, by arranging a radial coil connected in series with the focusing coil in the interior of the tracking coil is wound to automatically and quickly correct the tilt angle in accordance with the change in the focusing operation It is an object of the present invention to provide an optical pickup actuator.

In order to achieve the above object, the optical pickup actuator according to the present invention,

A lens holder for fixedly placing an objective lens capable of condensing a light beam on a data recording surface of the optical disc;

First and second permanent magnets disposed on left and right sides of the lens holder to form a magnetic field;

A focusing coil wound along a circumference of the lens holder and subjecting the lens holder to a magnetic force in a vertical direction;

Disposed on both sides of one side edge of the lens holder facing the first permanent magnet and one side edge of the lens holder facing the second permanent magnet, so as to receive a horizontal magnetic force from the lens holder. One tracking coil;

And a first radial coil and a second radial coil which are respectively disposed inside the outer tracking coil of the tracking coils and are electrically connected to the focusing coil .

Here, the first radial coil is disposed on the inner side of the outer circumference of the tracking coils disposed on one side of the lens holder, the second radial coil is horizontal to the tracking coil on which the first radial coil is disposed And a first radial coil and a second radial coil disposed on an inner surface of the tracking coil disposed on the other side of the lens holder opposite to each other, wherein the first radial coil and the second radial coil are focused when the focusing coil is forced up and down vertically by a magnetic field. Accordingly, the tilt angle of the disk is automatically corrected by receiving a vertical force from the magnetic field.

According to the present invention, there is an advantage in that a radial coil for tilt angle correction is inserted into the tracking coil, and the tilt angle of the optical disk can be corrected by using a conventional magnetic magnetic field according to the operation of the focusing coil during tilt angle correction.

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

5 is a view schematically showing an actuator structure according to the present invention.

As shown in Fig. 5, the objective lens 43 for condensing the light beam from the laser diode light source on the information recording surface of the optical disc, the lens holder 41 with the objective lens 43 inserted in the inner diameter, and the lens holder ( 41 and the first and second permanent magnets 46 disposed to be spaced apart from each other by a predetermined distance, and disposed on the rear surface of the first and second permanent magnets 46, respectively. Focusing disposed between the yoke 47 and the first and second permanent magnets 46 and wound around an outer circumference of the lens holder 41 to prevent magnetic flux leaking from the magnets 46. The coil 44 and the tracking coil 45 wound on the lens holder 41 in a direction perpendicular to the focusing coil 44 and a tilting angle disposed inside the tracking coil 45 although not shown in the drawing. (Tilting angle) It consists of the radial coil 50 for correction.

Although not shown, 49, which is not described, represents a wire spring.

The radial coil 50 is disposed inside the outer tracking coil 45 on the lens holder 41 adjacent to the first or second permanent magnets 46, the other being the radial coil 50. It is disposed inside the tracking coil 45 disposed on the other side of the tracking coil 45 including.

The operation of the actuator having the above structure is as follows.

The optical pickup actuator moves the lens holder 41 in which the objective lens 43 is disposed up, down, left and right for focusing and tracking operation of the objective lens 43. The driving force of the optical pickup actuator constitutes the tracking coil 45 and the focusing coil 44 in the magnetic space formed by the first and second permanent magnets 46 and the yoke 47 , and thus Fleming's left hand law. Caused by Lorentz force.

A current is applied to the tracking coil 45 to move the objective lens 43 of the optical pickup actuator from side to side, and a current is applied to the focusing coil 44 to move up and down. At this time, the first and second radial coils 50 connected in series with the focusing coil 44 are disposed in the tracking coil 45, and automatically move in accordance with the vertical movement of the focusing coil 44. Generate a tilt.

The tilt driving by the first and second radial coils 50 is for the correction of the tilt angle, which cannot be adjusted by the focusing operation and the tracking operation. The optical pickup actuator must be perpendicular to the disk surface on which the data is to be recorded / reproduced. This is because accurate data can be recorded / reproduced.

FIG. 6 is a cross-sectional view seen from the direction A of FIG. 5, and as shown, a focusing coil 44 is wound around a lens holder 41 including the objective lens 43. The tracking coils 45 are disposed on both sides of one side edge on which the c) is wound. Further, the first radial coil 50 for tilt angle correction is disposed inside the outer circumferential side of the tracking coil 45.

When the focusing coil 44 wound around the lens holder 41 where the objective lens 43 is positioned moves up and down, current is also applied to the first and second radial coils 50 based on the magnetic field. Under the force, it is tilted vertically. Therefore, since the first and second radial coils 50 are present in only one of each of the tracking coils 45 disposed on both sides of the lens holder, the first and second radial coils 50 are tilted to one side by the force caused by the magnetic field. The angle is corrected.

 7 is a view for explaining the force that the radial coil receives in the magnetic field due to the magnetic.

As shown in FIG. 7, the magnetic field due to the magnetic field has a strength of the magnetic field which decreases up and down symmetrically about the center. In the case of focusing up, when the radial coil 50 is present in the magnetic field, the strength of the magnetic field passing through the lower portion of the radial coil 50 is large, and the strength of the magnetic field passing through the upper portion is small. 50) will be comforted up.

In addition, since the radial coil 50 is electrically connected to the focusing coil 44 , the radial coil 50 receives a force up and down according to the up and down of the focusing coil 44. In order to better understand and explain in detail with respect to Figure 7 and Figure 3b as follows. That is, as shown in Fig. 3B, when the outer peripheral region of the disk is bent upward, the lens holder is raised upward by performing the focusing drive. At this time, the radial coil is also raised, and as described with reference to FIG. 7, according to the present invention, the radial coil formed in the outer circumferential direction of the disk in the actuator configuration is forced upward. Accordingly, as the lens holder is raised by the focusing driving, the tilt angle can be simultaneously corrected. On the other hand, as shown in Figure 3c, when the outer peripheral region of the disk is bent downward, the lens holder is lowered by performing the focusing drive, according to the present invention in the actuator configuration relative to the outer peripheral direction of the disk The formed radial coil is forced down. Accordingly, as the lens holder is lowered by the focusing driving, the tilt angle can be simultaneously corrected.

8 is a graph showing the disc tilt angle correction of the actuator according to the present invention.

As shown in Fig. 8, the tilt angle is generated by the disc bending or mechanical run-out. The tilt angle is increased in accordance with the distance for the focusing coil to focus the objective lens to read / write data. Increase nonlinearly

According to the radial coil proposed in the present invention, the tilt angle tracking of the actuator has a nearly linear linear slope. As the graph shows, it follows the tilt angle correction on the disc according to the focusing distance.

As described in detail above, the present invention automatically and accurately corrects the tilt angle by a radial coil connected in series with the focusing coil based on the focusing operation information of the optical pickup actuator. There is an advantage to this.

In addition, since the radial coil is disposed inside the tracking coil, the magnetic field used for the focusing operation and the tracking operation is used, so that there is no need to arrange a separate permanent magnet on the actuator.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

1 schematically shows the structure of an optical pick-up actuator according to the prior art;

2 illustrates the mechanism of an optical disk drive for reading data of a disk according to the prior art.

3A to 3C are views for explaining the correlation between the tilting operation and the focusing operation of the optical pickup actuator according to the run-out and mechanical failure of the disc;

4A and 4B are diagrams for explaining the concept of tilt angle correction of a disc.

5 schematically illustrates an actuator structure according to the invention.

6 is a sectional view seen from the direction A of FIG.

7 is a view for explaining a force received by the magnetic coil in the magnetic field by the magnetic field according to the present invention.

8 is a graph showing the disc tilt angle correction of the actuator according to the present invention.

           * Description of the symbols for the main parts of the drawings *

40: damper 41: lens holder

43: objective lens 44: focusing coil

45: tracking coil 46: permanent magnet

47: yoke 49: wire spring

50: radial coil

Claims (3)

A lens holder for fixedly placing an objective lens capable of condensing a light beam on a data recording surface of the optical disc; First and second permanent magnets disposed on left and right sides of the lens holder to form a magnetic field; A focusing coil wound along a circumference of the lens holder and subjecting the lens holder to a magnetic force in a vertical direction; Disposed on both sides of one side edge of the lens holder facing the first permanent magnet and one side edge of the lens holder facing the second permanent magnet, so as to receive a horizontal magnetic force from the lens holder. One tracking coil; And a first radial coil and a second radial coil , each of which is disposed inside an outer tracking coil of the tracking coils and electrically connected to the focusing coil . delete The method of claim 1, The first radial coil and the second radial coil automatically correct the tilt angle of the disk by receiving the vertical vertical force from the magnetic field when the focusing coil receives the vertical vertical force by the magnetic field. Optical pickup actuator.