KR100708103B1 - Actuator for optical pickup - Google Patents

Abstract

An optical pickup actuator is disclosed. An objective lens forming a spot on the disc for recording data on the disc or reading the data recorded on the data, a bobbin for fixing the objective lens, and the disc track radius of the bobbin Magnetic field generating means for generating a magnetic field toward one side parallel to the side and between the magnetic field generating means and the bobbin, the interaction with the magnetic field generating means to drive the bobbin in the focusing direction of the disk and A focusing coil is provided between the magnetic field generating means and the bobbin, and the bobbin is driven in a track radial direction of the disk by interaction with the magnetic field generating means. Tracking coils provided at both sides of the focusing coil, and a bezel for supporting the elements. Once the switch and the bobbin, but not in a state of being fixed on the base, and provides an optical pick-up actuators, it characterized in that it comprises a suspension for supporting the bobbin so movable.

Description

Actuator for optical pickup

1 is a schematic diagram of an optical pickup actuator according to the prior art.

2 is a plan view of an optical pickup actuator according to a first embodiment of the present invention.

3 is a perspective view of the optical pickup actuator according to the first embodiment of the present invention.

FIG. 4 is a right side view of FIG. 3, with the yoke omitted.

Fig. 5 is a plan view of an optical pickup actuator according to a second embodiment of the present invention.

6 is a right side view of the optical pickup actuator according to the second embodiment of the present invention, in which the yoke is omitted.

7 is a block diagram illustrating a correction circuit algorithm for correcting focus and tilt error of an optical pickup actuator according to an embodiment of the present invention.

   * Description of Signs of Major Parts of Drawings *

40, 70: Optical pick-up actuator 42: Base

44: holder block 46: York

48: Suspension 50: Bobbin

52: objective lens 54, 72: magnetic drive unit

56: magnetic field generating means 58: coil part

58a, 58b, 58c, 58d: first to fourth coils                 

60: magnetic field direction 74a: third coil

80: servo control system 82: focus correction unit

84: tilt correction unit 86: input separator

A1, A2, A3, A4: first to fourth bidirectional arrows

a1, a2: first and second arrows a3: bidirectional arrows

S1: Focus error signal S2: Tilt error signal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator for optical pickup, and more particularly, to an optical pickup actuator having a magnetic drive unit capable of simultaneously correcting focus and tilt errors.

Due to the rapid development of information technology, compact discs (CDs) or digital multi-function discs (DVDs) are used for recording and reading data by using highly coherent light such as lasers in magnetic recording media such as magnetic tapes that employ magnetic recording methods. Is replaced by an optical disk.

One of the characteristics of the optical disk is that data can be recorded at a higher density than conventional magnetic recording media. Despite these features, if the time taken to record and read data on the optical disc becomes long, the use of the optical disc becomes meaningless.                         

Higher density and higher speed of the optical disc are dictated by a device for recording data or reading recorded data at an appropriate position of the optical disc rather than the optical disc itself, that is, the optical pickup device.

On the other hand, the process of recording data on the optical disk or reading the recorded data is performed while the optical disk is being rotated at high speed. Therefore, it is necessary to keep the distance between the disk and the optical pickup device constant during the data recording process or the reading process. However, the distance between the disc and the optical pickup device is changed due to various reasons such as the size of the disc. Although this gap change is small, considering that the data is densely recorded on the disc, the change may cause an error in the data writing or reading process. In order to prevent such an error from occurring, the optical pickup device is provided with an actuator capable of focusing and tracking so as to follow a change in the distance between the disk and the optical pickup device due to the disk vibration, eccentricity, etc. of the disk.

Referring to FIG. 1, the actuator 1 of the optical pickup device according to the prior art is opposed to the disk 10 under the disk 10. On the surface facing the disk 10 of the actuator 1, an objective lens 31 having a focus on the disk 10 is provided, and light receiving parts 33 and 35 are provided on both sides thereof. The light receiving units 33 and 35 are provided at positions where the light irradiated onto the disk 10 through the objective lens 31 is reflected from the disk 10 and reached. The actuator 1 is mounted to the support 7 by a pivot shaft 70 penetrating the side surface. The motor 21 for tilt adjustment is connected to one end of the bottom surface of the actuator 1 via the rotation shaft 23. Therefore, the tilt generated between the disk 10 and the actuator 1 can be corrected by moving the actuator 1 in the direction to compensate for the tilt by the driving of the tilt motor 21. The support 7 is fixed to the slider 5, and the tracking motor 3 is provided in the slider 5. Therefore, the actuator 1 is moved in the track direction by the driving of the tracking motor 3.

When there is no tilt between the disk 10 and the actuator 1, the light irradiated from the objective lens 31 is reflected by the disk 10 and is incident on the light receiving units 33 and 35 provided on both sides of the objective lens 31. However, as shown in the drawing, when a tilt is generated between both, there is light that is not incident on the light-receiving portion among the light irradiated on the disk 10. This result is considered to sense the tilt of the disk 10, the tilt detection signal corresponding to the degree of tilt is generated in the light receiving portion (33, 35). The tilt detection signal becomes an input signal for driving the tilt motor 21 through the differential amplifier 37 connected to the light receiving units 33 and 35. According to the input signal, the tilt motor 21 is driven so that the actuator 1 moves in a direction to compensate for the generated tilt.

The actuator according to the prior art uses a motor to move the actuator in a direction to compensate for the disk tilt, so that the overall volume is increased and the structure is complicated. In addition, the moment of inertia of the actuator to be tilted is so large that it is difficult to correct for high-speed tilt of tens of hetz levels. From the fact that most of the tilt components generated in the rotation of the disc exist in the rotation frequency band, it can be seen that the actual disc tilt compensation is difficult with the actuator according to the prior art.

 Therefore, the technical problem to be achieved by the present invention is to solve the above-mentioned problems of the prior art, the structure is simple, the focus and tilt can be simultaneously compensated for high speed and the optical power that can reduce the power required for the overall volume and tilt compensation In providing an actuator of the pickup device.

In order to achieve the above technical problem, the present invention provides an objective lens for forming data on the disk or a spot for reading data recorded on the data, and a bobbin for fixing the objective lens ( bobbin), magnetic field generating means for generating a magnetic field toward one side parallel to the disk track radius of the bobbin, and between the magnetic field generating means and the bobbin, the bobbin in interaction with the magnetic field generating means. Is provided between the magnetic field generating means and the bobbin, and a focusing coil provided to drive the focusing direction of the disk and to control the tilt and focusing of the disk simultaneously. The bobbins may be provided on both sides of the focusing coil so that the bobbin can be driven in the track And a suspension for supporting the bobbin, with the base supporting the elements and a base for supporting the elements and one end fixed on the base, the bobbin being movable. .

The focusing coil is composed of first and second coils, and the tracking coil is composed of third and fourth coils provided on both sides of the first and second coils, respectively.                     

In addition, in order to achieve the above technical problem, the present invention is to record an object on the disk, or to form a spot on the disk for reading the data recorded on the data and the objective lens for fixing the A magnetic field generating means for generating a magnetic field toward a side surface parallel to the disc track radius of the bobbin, and between the magnetic field generating means and the bobbin, the bobbin being interacted with the magnetic field generating means. A tracking coil provided to be driven in a track radial direction of the disk, and between the magnetic field generating means and the bobbin, and driving the bobbin in a focusing direction of the disk by interaction with the magnetic field generating means. Spheres on both sides of the tracking coil to simultaneously control tilt and focusing of the disc. A non-focusing coil, a base for supporting the elements, and a suspension for supporting the bobbin with one end fixed on the base and supporting the bobbin so as to move, the optical pickup actuator is provided. .

The magnetic field generating means is supported by a yoke perpendicular to the base surface while being parallel to the track radial direction of the disc.

By using the present invention, the tilt and the focus according to the deformation of the disk can be adjusted simultaneously, and the optical pickup device can be reduced in size and weight. In addition, the power required for tilt and focus adjustment can be reduced.

Hereinafter, an optical pickup actuator (hereinafter, referred to as an actuator) according to the first and second embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the process, the thicknesses of the regions shown in the drawings are exaggerated for clarity.

<First Embodiment>

Referring to FIG. 2, the actuator 40 is mounted on a carriage (not shown), and a holder block 44 and a base 42 provided at one end of the base 42 and the base 42 which are transferred in a radial direction of the disk. Yoke (46) is provided at the other end of the. The holder block 44 is a plastic block. On the base 42 between the holder block 44 and the yoke 46 a bobbin 50 is provided which is a movable part. The bobbin 50 and the holder block 44 are fastened through the suspension 48, but are fastened so that the bobbin 50 can be moved by a magnetic force. The bobbin 50 is provided with an objective lens 52 facing the disk. The objective lens 52 is used to spot light incident from a light source (not shown) of the optical pickup device on the disk. A magnetic drive unit 54 is provided between the bobbin 50 and the yoke 46. The magnetic drive section 54 is to be fixed in contact with the radial side of the disk of the bobbin 50 between the magnetic field generating means 56, the bobbin 50 and the magnetic field generating means 56 fixed to the yoke 46 It consists of the coil part 58 provided. There is a gap between the magnetic field generating means 56 and the coil portion 58. The magnetic field generating means 56 is a magnet that generates a magnetic field toward a surface parallel to the disk radial direction of the bobbin 50, and a permanent magnet is preferable. If necessary, the magnetic field generating means 56 may be an electromagnet which generates the same magnetic field as the permanent magnet. The coil part 58 is comprised from the 1st-4th coils 58a, 58b, 58c, 58d. The first and second coils 58a and 58b are respectively wound so that the center of the winding is in a direction perpendicular to the surface of the base 42. The third and fourth coils 58c and 58d are provided on both sides of the first and second coils 58a and 58b, respectively, and face each other. And the third and fourth coils 58c and 58d are wound such that the center of the winding is parallel to the surface of the base 42.

Referring to FIG. 3, the holder block 44 is fastened perpendicularly to the surface of the base 42 at one end of the base 42, and the yoke 46 is a portion bent vertically to the surface of the base 42. have. The bobbin 50 is fastened to the holder block 44 by the upper part and the lower part through four suspensions 48.

4 shows the direction of the electromagnetic force generated by the interaction between the first magnetic field generating means 56 and the coil portion 58, and the yoke is not shown in side view or for convenience from the rear of the yoke.

In Fig. 4, reference numeral 60 denotes the direction of the magnetic field from the magnetic field generating means 56 toward the coil portion 58. The first bidirectional arrow A1 indicates the direction of the current applied to the first and second coils 58a and 58b, and the second bidirectional arrow A2 directs the current to the first and second coils 58a and 58b. The direction of the electromagnetic force exerted on the bobbin 50 by the interaction according to the Fleming's left hand rule between the magnetic field generating means 56 and the first and second coils 58a, 58b is applied.

In addition, the third two-way arrow A3 drawn on the third and fourth coils 58c and 58d indicates the direction of the current that can be applied to the third and fourth coils 58c and 58d. A4 is the magnetic field generating means 56 and the third and fourth bidirectional coils 58c as a current is applied to the third and fourth coils 58c and 58d in the same direction as the third two-way arrow A3. , 58d) represents the direction of the electromagnetic force applied to the bobbin 50 by the interaction between them.

Therefore, when an alignment error between the disc and the objective lens 50 occurs, such as a tilt error or a focus error, by selectively applying a current to the first and second coils 58a and 58b together with the magnetic field generating means 56. The objective lens 50 may be driven in a direction to compensate for the error. The disk tracking can also drive the objective lens 50 to a desired position by selectively applying current to the third and fourth coils 58c and 58d together with the magnetic field generating means 56.

Second Embodiment

When the same reference numerals as those in the first embodiment are described in the description, the members indicated by the reference numbers mean the same as the members in the first embodiment. Therefore, the description of the members described with the same reference numerals will be omitted.

The actuator according to the second embodiment has a magnetic drive part composed of the first and the coil parts similarly to that of the first embodiment, but the configuration of the coil part is different from that of the first embodiment.

Specifically, referring to FIG. 5, the magnetic drive unit 72 of the optical pickup actuator 70 according to the second embodiment is composed of a magnetic field generating unit 56 and a coil unit 74. The coil part 74 is comprised from the 1st and 2nd coils 58a and 58b and the 3rd coil 74a located between them. The third coil 74a is the same as the third coil (58c in FIG. 2) or the fourth coil 85d of the first embodiment, and is used for the disk tracking together with the magnetic field generating means 56.                     

FIG. 6 shows the operating principle of the actuator according to the second embodiment, in which the first and second arrows a1 and a2 indicate the magnetic field generating means 56 between the first and second coils 58a and 58b. The direction and relative magnitude of the electromagnetic force acting on the objective lens 50 by the interaction are shown. This electromagnetic force can adjust the tilt and focus errors generated between the disk and the objective lens 50. In other words, the compensation of focusing and focus error is controlled by the average value of the two forces represented by the first and second arrows a1 and a2, and the tilt error is represented by the two forces represented by the first and second arrows a1 and a2. Compensate by using the rotation momentum generated by the difference of.

The two-way arrow a3 indicates the direction of the electromagnetic force applied to the objective lens 50 by the interaction between the magnetic field generating means 56 and the third coil 74a. As can be seen from the arrangement relationship between the first and second coils 58a and 58b and the third coil 74a, the electromagnetic force represented by the two-way arrow a3 is represented by the first and second arrows a1 and a2. Perpendicular to the electromagnetic force. Since the electromagnetic force represented by the two-way arrow a3 is in a direction parallel to the radius of the disk, the disk tracking can be implemented using this force.

7 illustrates an algorithm for tilt and focus error correction, in which the focus error and tilt error signals S1 and S2 are transferred to the focus correction unit 82 and the tilt correction unit 84 of the servo control system 80, respectively. Is entered. At this time, the focus correction unit 82 calculates an average value of currents to be applied to the coils wound on the first and second coils 58a and 58b based on the focus error signal S1, and the tilt correction unit 84 tilts. The difference value of the current is calculated based on the error signal S2. Each current value thus calculated is divided into current values to be applied to the first and second coils 58a and 58b through the input separator 86 and applied to each of the coils C1 and C2. When such a current value is applied to the first to third coils 58a, 58b, 74a, the first and second arrows a1 are applied to the objective lens 50 by the magnetic field generating means 56 and the interaction according to the Fleming's left hand law. , a2) acts, and as a result, it is possible to simultaneously compensate for focus and tilt errors caused by various factors such as bending of the disc.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, those skilled in the art may have a different configuration of the coil unit 58 provided between the magnetic field generating means 56 and the bobbin 50. In other words, the number of coils constituting the coil unit 58 may be increased or its shape may be modified in another form. In addition, the strength of the magnetic field directed from the magnetic field generating means 56 to the coil portion 58 or 74 may be changed through the deformation of the magnetic field generating means 56. Because of this diversity of the present invention, the scope of the present invention should not be defined by the embodiments described, but by the technical spirit described in the claims.

As described above, the actuator of the present invention includes first and second coils for focusing and focus error correction and one or two coils for tilt error correction between the bobbin and a magnet which is a magnetic field generating means. By using this, correction for focus and tilt errors can be implemented simultaneously, and the actuator can be made smaller and lighter. In addition, the power required for tilt and focus adjustment can be reduced compared to using a motor.

Claims (12)

An objective lens for forming a spot on the disc for recording data on the disc or reading data recorded on the data; A bobbin fixing the objective lens; Magnetic field generating means for generating a magnetic field toward one side parallel to the disk track radius of the bobbin; A focusing coil provided between the magnetic field generating means and the bobbin, the focusing coil being configured to drive the bobbin in a focusing direction of the disk and to simultaneously control tilt and focusing of the disk by interacting with the magnetic field generating means; A tracking coil provided between the magnetic field generating means and the bobbin, and provided on both sides of the focusing coil so that the bobbin can be driven in a track radial direction of the disc by interaction with the magnetic field generating means; A base supporting the elements; And An optical pick-up actuator, characterized in that it comprises a suspension for supporting the bobbin with one end fixed on the base, the bobbin to move. The method of claim 1, The magnetic field generating means is an optical pickup actuator, characterized in that the permanent magnet provided perpendicular to the base surface. The method of claim 2, And the permanent magnet is supported by a yoke perpendicular to the base surface while being parallel to the track radial direction of the disc. The method of claim 1, The focusing coil is an optical pickup actuator, characterized in that consisting of the first and second coils. The method of claim 4, wherein The tracking coil is an optical pickup actuator, characterized in that consisting of the third and fourth coils each provided on each side of the first and second coils. The method of claim 4, wherein And the first and second coils have a center of their winding wound perpendicular to the base surface. The method of claim 5, And the third and fourth coils are provided on both sides of the first and second coils, with the centers of the windings wound in parallel to the base surface, respectively. An objective lens for forming a spot on the disc for recording data on the disc or reading data recorded on the data; A bobbin for fixing the objective lens; Magnetic field generating means for generating a magnetic field toward one side parallel to the disk track radius of the bobbin; A tracking coil provided between the magnetic field generating means and the bobbin, the bobbin being driven in the radial direction of the track of the disk by interaction with the magnetic field generating means; It is provided between the magnetic field generating means and the bobbin, both sides of the tracking coil so as to interact with the magnetic field generating means to drive the bobbin in the focus direction of the disk and to control the tilt and focusing of the disk at the same time Focusing coil provided in; A base supporting the elements; And An optical pick-up actuator, characterized in that it comprises a suspension for supporting the bobbin with one end fixed on the base, the bobbin to move. The optical pickup actuator of claim 8, wherein the focusing coil comprises first and second coils each provided on both sides of the tracking coil. The method of claim 9, The tracking coil is an optical pickup actuator, characterized in that the third coil provided between the first and second coil. The method of claim 9, And the first and second coils have a center of their winding wound perpendicular to the base surface. The method of claim 10, And the third coil is provided between the first and second coils with the center of the winding wound parallel to the base surface.

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