KR100548246B1 - Lens projection type actuator for optical disc drive - Google Patents

Abstract

The present invention relates to a lens protruding actuator, comprising: a lens holder including an objective lens, a coil and a magnet for moving the lens holder, and an actuator including a support member for supporting the lens holder, wherein the objective lens is a lens holder. It is arranged so as to be offset by a predetermined interval toward the center of the disk seated on the spindle motor in the radial direction without being in the center of the. In addition, the left and right wire suspensions disposed before and after the lens holder and the left and right damper holders are arranged on the same plane. The present invention relates to an objective lens arrangement for securing more recording capacity in an ultra-small and ultra-thin disk drive, and a structure in which wires are arranged in a plane to facilitate thinning, and the objective lens is centered on a lens holder. By arranging the disc in the radial direction of the disk, the lead-in area of the data can be set closer to the center, so that a substantial increase in the recording capacity can be expected. In addition, it is possible to reduce the thickness while acting as a power terminal for two-axis driving.

Description

Lens projecting actuator for optical disk drive {LENS PROJECTION TYPE ACTUATOR FOR OPTICAL DISC DRIVE}

1 to 4 are diagrams of a conventional optical pickup actuator,

1A and 1B are schematic plan and front views of a conventional optical pickup actuator.

2 is a schematic diagram showing tilt angle correction of a disc by an actuator.

3 is a view simulating the pitching mode of the actuator.

4 is a view illustrating a phenomenon in which the tilting operation is coupled during the focusing operation in the first stage wire structure of the actuator.

Fig. 5 is a plan view showing the relationship between the shape and the size of the signal pit and the beam diameter on the read-only optical disc information surface;

Figure 6 is a perspective view showing the support structure of the actuator according to the prior application.

7 is a side cross-sectional view of the actuator of FIG.

8 to 10 are views of the optical pickup actuator according to the present invention,

8 is a plan view showing the arrangement of the objective lens of the optical pickup actuator.

9 is a side view showing the arrangement of the objective lens of the optical pickup actuator.

10 is a perspective view showing an objective lens arrangement of the optical pickup actuator.

11 is a perspective view showing the arrangement of the optical pickup actuator mainly used in the existing notebook.

<Description of the symbols for the main parts of the drawings>

301: objective lens

302: Lens Holder

302a: projection

307,308: Left and right damper holder

309,310: Left and Right Wire Suspension

400: spindle motor

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lens projection actuator of an optical pickup, in which information required for an optical disk drive device is converted into an optical signal using a laser beam to record and reproduce on an optical disk. The lead-in area of the data, which is arranged in a biased direction, and which determines the recording capacity of the disc, is set toward the inner circumferential side of the disc, so that the lead-in area of the data can be set closer to the center so that a substantial increase in the recording capacity can be expected. The present invention relates to a lens protruding actuator configured to provide a structure suitable for a micro actuator while suppressing unnecessary rotational behavior in driving the actuator.

The actuator keeps the relative position between the objective lens and the disc by moving a structural element such as a lens holder including the objective lens, and records the information recorded on the disc by following the track of the disc. Plays a role The actuator moves in the form of a movable coil by a permanent magnet field to move the objective lens to a desired position. At this time, the movable part is designed to have the desired frequency characteristics by fixing it with a support having rigidity and attenuation characteristics. The movable part translates in two directions perpendicular to each other, focusing and tracking directions, and rotates or twists to reduce an error of the optical signal. The driving should be made without unnecessary vibration such as.

In addition, the actuator is connected in a form in which four spring wires support the lens holder, and a focusing coil and a tracking coil are attached to the lens holder for driving the actuator. In addition, yokes and permanent magnets are installed around the moving parts to generate electromagnetic fields.

1 to 4 are views of a conventional optical pick-up actuator, in which Fig. 1 (a) and (b) show schematic plan and front views of a conventional optical pick-up actuator, respectively, and in Fig. 2 the tilt of the disc by the actuator. A schematic diagram showing each correction is shown. FIG. 3 is a diagram illustrating a pitching mode of an actuator, and FIG. 4 is a diagram illustrating a phenomenon in which a tilting operation is coupled during a focusing operation in a single-stage wire structure of the actuator.

As shown in the drawing, an objective lens 101 is mounted at a central portion thereof, and a lens holder 102 coupled with coils 105 and 106 for tracking and focusing to an outer circumferential surface thereof, and installed at both sides of the lens holder 102. Magnets (magnet, 103) and yoke (Yoke, 104), the upper and lower plurality of wire suspension (107), one end is fixed to the upper and lower sides of the lens holder 102 to support it, and The damper holder 109 is provided on one side of the lens holder 102 and the other end of the wire suspension 107 is fixed.

Reference numeral 108 is a fixed substrate, which is formed on and under the lens holder 102 so that one end of the wire suspension 107 is soldered and fixed.

Referring to the attached optical pickup actuator as described above with reference to the accompanying drawings as follows.

The objective lens 101 is mounted on the lens holder 102, and a focusing coil 105 is wound around the lens holder 102 for focusing, and wound around the corner holder in an appropriate direction with each other for tracking. The tracking coil 106 is attached.

In addition, a plurality of yokes 104, which are ferromagnetic materials, protrude from left and right sides of the lens holder 102 to fix the magnets 103, respectively. The yoke 104 is integrated with the pickup base (not shown) by an integration means.

The fixing substrate 108 is coupled to the upper and lower side centers of the lens holder 102, and one end of two parallel wire suspensions 107 is soldered to each of the fixing substrates 108, and the wire suspension 107 is attached thereto. The other end of is fixed through the damper holder 109 provided on one side of the lens holder 102.

Here, a damper (not shown) is coupled to the damper holder 109 so as to have a rigid damping characteristic of the wire suspension 107, and a main substrate (not shown) is coupled to the outside so that the wire suspension 107 is connected to the damper holder 109. Make sure that the other end of is soldered.

 The lens holder 102 is floated by the wire suspension 107, and a current is supplied to each of the wire suspensions 107.

In this structure, the tracking coils 106 attached to the lens holders 102 are wound in proper directions with each other to generate magnetic flux in a predetermined direction when current flows thereto, which is caused by the magnet 103 and the electromagnetic force which are fixed. And repulsive force is generated.

By the repulsive force and the repulsive force as described above, the movement of the lens holder 102 moves in the tracking direction (before and after), so that the tracking servo for correcting the tracking error is operated.

In addition, the focusing coil 105 is wound in a vertical direction differently from the tracking coil, and when the current flows, the direction of the magnetic flux is generated in the up and down directions. By generating a force, the lens holder 102 is moved in the focusing direction (up and down), so that a focusing servo for correcting this is operated.

The coils 105 and 106 are wound around the outer circumferential surface of the lens holder 102 to move the coil together with the lens holder 102, which is called a moving coil method. On the contrary, a magnet is attached to the outer circumferential surface of the lens holder and the lens holder is The movement of the magnet together is called the moving magnet method. At this time, the moving method by magnet and coil uses Lorentz force of Fleming's left hand law.

When such an optical pickup actuator applies current to the focusing coil 105 placed in a magnetic field, electromotive force is generated in the coil, and the electromotive force drives the movable part in the vertical direction (optical axis direction, focusing direction). In the same manner, when a current is applied to the tracking coil 106, the movable portion moves in the left and right direction (tracking coil direction). By this principle, the reflective surface on the disc Disc in which the signal pit is recorded can be maintained within the depth of focus of the laser beam emitted from the objective lens 101, and the track on the disc ( Track can be tracked.

Fig. 5 is a plan view showing the relationship between the shape and the size of the signal pit and the beam diameter on the read-only optical disc information surface, where 1 is a signal (feet) (depth λ / 4N), and 2 is a laser spot (diameter). 1.6 μm), L1 indicates track pitch (1.6 μm), and L2 indicates pit width (˜0.4 μm).

Hereinafter, referring to FIG. 5, the effect of tilt generation on signal degradation in relation to recording density is important. In order to read a signal (feet) generated on a disk, the size of the focused beam is important. As shown in FIG. 5, the size of the beam is determined at a level slightly larger than that of the signal for the determination of the signal (feet). Therefore, in order to read a small signal, the size of the condensing beam must be small. For this purpose, a laser having a small wavelength λ and an objective lens having a large numerical aperture (N.A.) are required. The diameter of the condensing beam may be expressed as in Equation (1).

Diameter of condensing beam = 0.82 x lambda /N.A. ........... (One)

On the other hand, the tilt margin of the optical disk drive control system is controlled by the characteristics of the optical component and has the condition of Equation (2). Tilt components due to warpage and mechanical run-out degrade the jitter and adversely affect the control system. Generally, tilt angles of 0.5 ° for CD and 0.2 ° for DVD are allowed.

Tilt margin ∝ λ / N.A3 ..... (2)

In order to correct the tilt component, the actuator must be operated in the tilting motion mode in the radial (X-axis rotation mode) and tangential (Y-axis rotation mode) as well as the translational motion in the tracking and focusing directions. However, in the conventional structure, the tilt motion was impossible to operate.

That is, in the structure of the magnetic field structure (magnet and coil) and the plurality of wire suspensions shown in FIG. 1, the lens holder 102 can easily perform the translational movement in the tracking and focusing direction, but not the tilting movement.

On the other hand, as shown in Figure 4 in the actuator that supports the wire suspension to one side of the lens holder 202 in one stage structure only in one direction, the unwanted tilting angle always occurs during focusing or tracking movement, tilting control using servo Even possible actuators have problems that cause excessive load on the system.

The present inventors have been created to solve the above problems, in order to support the movement of the lens holder in which the objective lens is mounted in the translational and tilting motion mode, a pair of damper holder, the damper holder and the lens holder A pair of wire suspensions are installed on one plane in parallel between left and right sides, and one pair of the wire suspensions can be fixed and installed as a pair of free ends, so that the translational and double tilting motions of the lens holder can be achieved. Invented a support structure for an actuator capable of a tilting drive so that it can be easily made, and has previously filed it.

This prior application (name: the support structure of the actuator of the support structure of the optical pickup actuator, Patent Registration No. 10-0364353), a lens holder including an objective lens, a coil and a magnet for moving the lens holder, and the lens holder A first elastic support composed of a pair of damper holders having a supporting member supported on one side of the lens holder, and a pair of wire suspensions having one end connected to one side of the lens holder and a fixed end connected to one side damper holder; Means and a pair of wire suspensions having one end connected to the other side of the lens holder and a free end connected to the other damper holder, and including second elastic support means forming the same plane as the first elastic support means. The first and second elastic support means are parallel to each other on the same plane, and have the same spring constant.

Figure 6 is a perspective view showing the support structure of the actuator according to the prior invention, Figure 7 is a side cross-sectional view of the actuator of Figure 5 of the prior invention.

6 and 7, a lens holder 302 having an objective lens 301 at a center thereof and a plurality of magnets 303 installed at left and right sides thereof; Yokes (304) provided with coils (305, 306) for tracking and focusing on the left and right sides of the lens holder (302); A pair of damper holders 307 and 308 disposed outside the lens holder 302, and a pair of left and right pairs of wires disposed at left and right centers of the pair of damper holders 307 and 308 and the lens holder 302, respectively. It is composed of suspensions 309 and 310.

In detail, the damper holders 307 and 308 have a structure in which pairs face each other at the left and right ends of the lens holder 302, and a damper 311 is provided therein. One end of the wire suspension 309 and 310 penetrates through the left damper holder 307 and the internal damper 311 to protrude outside the insertion hole 315 of the main substrate 313 to be fixed by soldering 314 and the other end thereof. An insertion hole 315 of the main substrate 313 through the pair of left wire suspension 309 connected to the fixed substrate 312 provided in the lens holder 302 and the right damper holder 308 and the internal damper 311. ) Is fitted with one pair of right side wire suspensions 310 connected to fixed substrates 312 provided on the lens holder 302.

Referring to the accompanying drawings, the supporting structure of the actuator capable of tilting driving according to the pre-opened invention configured as described above is as follows.

First, as shown in FIGS. 6 and 7, an objective lens 301 is mounted at the center of the lens holder 302, and a plurality of magnets 303 are provided at left and right sides thereof, respectively, and the magnet 303 is provided. The focusing coil 305 and the tracking coil 306 are wound around the yoke 304 to the left and the right of the lens holder 302 facing each other.

In addition, a pair of damper holders 307 and 308 having wire ends 309 and 310 fixed to the lens holder 302 and opposite ends of the wire suspensions 309 and 310 for supporting the operation of the lens holder 302 are provided on both sides of the lens holder 302. Is installed on.

Here, a damper 311 having damping characteristics is provided inside the damper holders 307 and 308, and a pair of wire suspensions 309 on the left side of the damper 311 are soldered to the main substrate 313. It is fixed and a pair of wire suspension 310 on the right side is installed in the state inserted in the insertion hole 315. Here, the wire suspension 310 may be laid in parallel without falling down because it has a constant rigidity without being fixed.

The magnetic circuit structure of the actuator includes a focusing coil divided into four and a pair of tracking coils, and the driving in the radial direction and the tangential direction is also possible by controlling the current ratio applied to the four focusing coils. .

The wire suspensions 309 and 310 which hold the lens holder 302 are located on a plane parallel to each other on the left and right sides, so that a pair of damper holders are provided on the side of the lens holder 302 and both sides thereof. Since it is installed between the 307, 308, it is supported when the lens holder 302 is operating.

In this way, the support structure of the wire suspensions 309 and 310 can secure driving freedom with respect to the translational movement in the tracking and focusing direction of the lens holder 302 and the tilting movement in the tangential and radial directions.

To this end, a pair of wire suspensions 309, which are installed on the left side of the lens holder 302 and extended to the damper holder 307, are soldered and fixed to the main substrate 313, and extend to the right side of the lens holder 302. A pair of right side wire suspensions 310 are installed without being fixed to the insertion hole 315.

In the above-described invention, the fixed spring suspension at the fixed end-free end is larger than the spring constant at the free end (K1> K2), so that the spring constants at both ends are the same. The elastic modulus E2 of the free end wire suspension 310 is made larger than the elastic modulus E1 of (), or the moment of inertia of the free end wire suspension 310 is greater than the moment of inertia I1 of the fixed end wire suspension 309. What is necessary is just to make (I2) larger, or length L1 of the fixed wire suspension 309 longer than length L2 of the free end wire suspension 310. FIG. In addition, such elastic modulus, moment of inertia, and length may be adjusted in combination to make the spring constant K1 of the pair of left wire suspensions 309 and the spring constant K2 of the pair of right wire suspensions 310 the same.

(r=반지름)이 되며 판스프링일 때

(b=가로,h=세로)이 된다.In addition, the ratios satisfying the conditions of the spring constant (K1 = K2) are L1 / L2 = 1.45, I2 / I2 = 1.22, and E2 / E1 = 2.23. While adjusting, wire suspensions 309 and 310 having the same spring constant at both ends can be installed. Where the moment of inertia is when the wire suspension is a wire

(r = radius) and when it is leaf spring

(b = horizontal, h = vertical).

Where E1, E2 is the elastic modulus of the wire, I1, I2 is the moment of inertia, and K1, K2 is the spring constant.

As described above, the support structure of the actuator capable of tilting driving according to the above-described invention supports the lens holder with a pair of damper holders and two pairs of wire suspensions, while the left wire suspension for supporting the lens holders is fixed. And the right wire suspension is installed without fixing, and the left and right wire suspensions have the same spring constant, so that the stiffness of the translational motion is not changed as compared with the actuator of the conventional two-stage supporting structure. It is possible to reduce the stiffness of the tilting (particularly the tangential direction) to the level at which strength can be obtained, and to drive each of the independent motion modes.

It is also possible to apply eight wire suspensions on one plane, making it easy to supply power to the electromechanical device for focusing, tracking, radial and tangential driving of the lens holder in the moving coil type multi-axis actuator. It can be effective.

In optical disc drives, the effective recording space size is determined by the position of the data lead-in area of the disc, and the lead-in area is determined by the size of the actuator and the space occupied by the spindle motor. In comparison, since the size of the actuator and the spindle motor is relatively large, when the optical pickup actuator as described above is adopted, it is difficult to set the lead-in area on the inner circumferential side of the disk.

The present invention has been made to solve the above problems and defects as described above, and relates to the structure of an optical pickup actuator that can be used in an ultra-compact, ultra-thin optical information storage device, wherein the objective lens is a lady of the disc at the center of the lens holder. The lead-in area of the data, which is arranged in a displaced direction, is set toward the inner circumference of the disk, so that the lead-in area of the data can be set closer to the center, and a substantial increase in the recording capacity can be expected. It provides a structure suitable for a very small actuator while suppressing unnecessary rotational behavior in driving of the actuator, so that the position of the objective lens and the supporting structure of the movable part in the movable part of the actuator can be more advantageous in terms of ultra small and ultra thin. Purpose to provide actuator There is this.

The optical pickup actuator keeps the relative position between the objective lens and the disc by moving the lens holder including the objective lens, and records / plays the information recorded on the disc by following the track of the disc. . In addition, the actuator moves in the form of a movable coil by a permanent magnet magnetic field to move the objective lens to a desired position. At this time, the movable part is designed to have the desired frequency characteristics by fixing it with a support having rigidity and attenuation characteristics. The movable part translates in two directions perpendicular to each other, focusing and tracking directions, and rotates or twists to reduce an error of the optical signal. The driving should be made without unnecessary vibration such as.

In addition, in order to actually apply the planar four-wire support structure according to the present invention, one side of the wire fixing end is fixed by soldering, and the other side is not fixed to the wire to absorb the longitudinal change of the wire during tracking and focusing motion. It should be manufactured in simple supporting form.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail as follows.

8 to 10 are views of the optical pickup actuator according to the present invention. FIG. 8 is a plan view showing the arrangement of the objective lens of the optical pickup actuator, and FIG. 9 is a side view showing the arrangement of the objective lens of the optical pickup actuator. 10 is a perspective view illustrating an objective lens arrangement of the optical pickup actuator.

Hereinafter, referring to FIGS. 8 to 10, 300 is an optical pickup actuator to which the present invention is employed, 302 is a lens holder, 400 is a spindle motor, and D is a disk.

As shown in the drawing, the size of the effective recording space is determined by the position of the lead-in area of the data. In general, the lead-in area is determined by the size of the actuator and the space occupied by the spindle motor 400. In the case of a small disc device having a small disc size, the size of the actuator and the spindle motor 400 is larger than that of the disc. It is difficult to set the phosphorus region on the inner circumferential side of the disc.

The support means which are generally used is a four-wire system as shown in Fig. 1B, and this structure is a structure that can smoothly move in the tracking and focusing directions and can appropriately suppress the movement in other rotational directions. However, in ultra-thin devices, it is not easy to arrange the wire up and down. If the arrangement is done as shown in Fig. 4, the rotation mode can be easily excited, causing the rotation to be larger than the tilt tolerance described in the previous section, resulting in signal degradation.

The present invention relates to an objective lens arrangement and a support structure of an actuator. The present invention relates to an objective lens arrangement for setting the lead-in area to the inner circumference as much as possible. It is possible to provide a support structure that is both ultra thin and flexible.

In the optical pickup actuator according to the present invention, as shown in FIGS. 8 to 10, the objective lens 301 is not located at the center of the lens holder 302 but is spaced a predetermined distance toward the center of the disc seated on the spindle motor 400 in the radial direction. It has a structure arrange | positioned at the protrusion part 302a of the jersey lens holder 302. As shown in FIG. The reflection mirror 320 is disposed below the objective lens 301.

In addition, unlike the existing four-wire support method, the four wires, that is, the left and right wire suspensions 309 and 310 disposed before and after the lens holder 302 and the left and right damper holders 307 and 308, are the same. The structure is arranged on the plane.

The optical pickup actuator according to the present invention has a planar 4-wire support structure in which four wires are arranged on a plane, thereby minimizing the height of the optical pickup actuator. The following describes the features of this approach in detail.

As shown in FIG. 11, the lens protrusion optical pickup actuator of the present invention is different from the slim lens protrusion structure mainly used in the existing notebook. In the slim type, the objective lens 301 'is protruded in the tangential direction of the disc from the lens holder 302' supported by the support 307 'to reduce the distance from the reflective mirror 320' in order to reduce the basic height of the actuator. In the present invention, as shown in Figs. 8 to 10, the objective lens 301 is protruded in the radial direction of the disk so that the lead-in area can be set on the inner circumferential side of the disk without miniaturizing the main parts of the actuator.

The present invention employs the lens protrusion structure and the planar 4-wire support structure as described above, so that the lens holder, the VCM (Voice Coil Motor) part, and the wire, which occupy most of the height of the optical pickup actuator, are not disposed on the inner circumferential side of the disc. Only optically necessary objective lenses and reflective mirrors can be arranged on the inner circumferential side. Interference with spindle motors is a major problem in micromachines, but the same effect can be achieved without miniaturizing the entire actuator.

In addition, by adopting a planar four-wire support structure to support both ends, it is possible to minimize the rotational motion as shown in FIG. Therefore, it is possible to obtain a dynamic characteristic similar to the existing four-wire support method, while reducing the height space between the wire and the wire, and it is possible to use four wires as a power terminal connected to the coil for biaxial movement.

As described above, the present invention relates to an object lens arrangement for securing more recording capacity in an ultra-small and ultra-thin disk drive, and a structure in which wires are arranged on a plane to facilitate thinning. By arranging the lead-in area of the data closer to the center by arranging it in the radial direction of the disc at the center of the holder, it is possible to expect a substantial increase in the recording capacity, and by rotating the wire on both end planes. This is suppressed, and while acting as a power supply terminal for two-axis driving, there is an effect that can be thinned.

Claims (2)

An actuator comprising a lens holder including an objective lens, a coil and a magnet for moving the lens holder, and a support member for supporting the lens holder, wherein the objective lens is not centered on the lens holder but is in a radial direction. And a lead-in area of the data which determines the recording capacity of the disk is set toward the inner circumference of the disk so as to be close to the center of the disk, and is disposed on the projection of the lens holder so as to be spaced a predetermined distance toward the disk center seated on the disk. Lens projection actuator for optical disc drives. The lens projection actuator of claim 1, wherein the left and right wire suspensions disposed before and after the lens holder and the left and right damper holders are arranged on the same plane.

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