KR20020028628A - Piezoelectric Actuator For Optical Pick-up Device - Google Patents

Abstract

PURPOSE: A device for driving an objective lens of an optical pickup is provided to drive the objective lens in focusing/tracking and tilting directions rapidly and minutely, to correctly adjust a focus of the objective lens to a pit. CONSTITUTION: Operating members(102,102a) connected with a lens holder(101) fixing and supporting an objective lens(101a) have piezos(200) that are displaced by an electric potential difference, to drive the objective lens(10a) in focusing and tilting directions. Tracking driving units(103,103a) connected with the operating members(102,102a) have plate-shaped piezos(300) that are displaced by an electric potential difference, to drive the objective lens(101a) in a tracking direction. Driving members(105) connected to each tracking driving unit(103,103a) deliver a driving force of the tracking driving unit(103,103a) to the objective lens(101a). And a connection member(104) connected with the driving members(105) is located between the operating members(102,102a) to deliver a tracking driving force of the driving members(105) to the objective lens(101a).

Description

Objective Pick-up Device for Optical Pickup {Piezoelectric Actuator For Optical Pick-up Device}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an objective lens driving apparatus for optical pickup, and more particularly, to tilt and move the lens faster and finer in the focusing / tracking direction so that the focus of the optical pickup objective lens can be accurately adjusted to the pit. The present invention also relates to an objective lens driving apparatus of an optical pickup, which is also carried out in the direction of) to quickly correspond and correct an inclination angle between an objective lens and a disc.

In general, an optical recording player using an optical recording medium (optical disk) such as a laser disk player (LDP) and a compact disk player (CDP) scans a light beam such as a laser onto a disk surface and detects the light beam reflected from the disk. Optical pickup unit is installed.

The optical pickup unit scans the light beam through the objective lens onto the disk surface and reads the reflected beam as a binary signal. In order for the optical pickup unit to read the signal correctly, a certain distance, i.e., the focus, between the objective lens to which the light beam is scanned and the disc must be precisely focused, while the scanned light beam must follow the track formed on the disc precisely. It is possible.

The focal length maintenance of the objective lens according to the operation of driving the objective lens is referred to as tracking (horizontal direction) and the movement of the objective lens along the disc track is called tracking (horizontal direction). There is an objective lens driving apparatus for performing a focusing / tracking operation while driving an objective lens.

Figure 1 is an exploded perspective view showing a conventional wire spring-supported two-dimensional actuator, Figure 2 is a side view of the operating state showing the focusing actuator structure of Figure 1, Figure 3 is a perspective view showing the circumference of the disk.

1 shows a typical wire spring-supported two-dimensional optical pickup actuator, the main part of which is provided with a base 1 on which a magnet 2 and a yoke 3 are formed to form a magnetic field, and on the base 1. A holder (4) to be fixed, a plurality of wires (5) having one end fixed to the holder (4) and connected to a power source, and coupled to the other end of the wire (5) to support horizontal / vertical movement, A focusing coil that generates an electromagnetic force by interacting with a coil holder 7 on which an objective lens 6 is placed on one side and a magnetic field formed by a magnet 2 and a yoke 3 wound around the coil holder 7 ( 8) and the tracking coil 9, and a current to be transmitted to the focusing coil 8 and the tracking coil 9 through the wire (5).

Therefore, the objective lens 6 and the focusing coil 8 / tracking coil 9 attached to the coil holder 7 are supported by several wires 5, and the yoke 3 is attached to the magnet 2 at the bottom thereof. As shown in FIG. 2, the focusing coil 8 and the tracking coil 9 form a magnetic field and a magnetic circuit generated by the magnet 2 to focus according to the flaming left hand law. The objective lens 6 is driven vertically / horizontally, vertically and horizontally in the focusing (vertical) direction and the tracking (horizontal) direction.

At this time, the magnitude of the force is determined in proportion to the relationship between the magnetic flux density of the magnet, the effective length of the coil, the number of turns, and the strength of the current.

The range in which the objective lens 6 is driven in the focusing (vertical) direction is ± 1 to 2 mm, and in the tracking (horizontal) direction is about ± 0.3 to 0.5 mm.

When a CD having such a driving range is reproduced, it is designed to follow ± 1 μm in the focusing (vertical) direction and ± 0.1 μm in the tracking (horizontal) direction.

As the speed of reproduction and recording of the disc 10 increases as described above, in order to reproduce up to 40 times the speed of the disc 10, it is required to drive the objective lens 6 faster, and further, in the tracking (horizontal) direction. It is necessary to drive with 10 times the accuracy of the focusing (vertical) direction. Therefore, in the same way as the wire spring-supported two-dimensional actuator (objective driving device), it is difficult and limited to drive the objective lens quickly and properly in the focusing / tracking direction, and it is driven by using a coil only in the magnetic field. The efficiency is low, but it is numerically not more than about 50%.

In addition, since the spring-supported two-dimensional actuator is structurally integrated with a focusing / tracking driving unit, interference and crosstalk phenomena occur between each other, so that the separation of the driving is not complete. This causes a series of unnecessary vibration modes, thereby degrading the stability of the playback and recording operations.

In addition, as shown in FIG. 3, since the disk 10 is circular in shape but the circumference of the disk 10 is slightly bent, the disk 10 may have a disk 10 when the driving part of the spring-supported actuator rotates rapidly. Distortion or vibration of the track direction increases, and because of this, the inclination angle between the objective lens and the disc 10 is not constant. Therefore, it is impossible to perform a driving operation that can cope with and correct this inclined angle, so that the disc 10 is accurate. Since accurate reproducing and recording operations are impossible, the reliability of the product has been deteriorated.

Accordingly, the present invention is to solve the above-mentioned conventional problems, the object of the present invention is to quickly and finely focus the lens in the focusing / tracking and tilting direction so that the focus of the optical pickup objective lens to exactly fit (Pit) By providing accurate driving, an optical pickup objective lens driving device can perform a stable and stable disc playback and recording by performing a precise and accurate driving force by quickly responding and correcting an inclination angle between an objective lens and a disc. .

In order to achieve the above object, the objective lens driving device of the optical pickup of the present invention is connected to a lens holder for fixing and supporting the objective lens, so that the piezo is displaced by a potential difference so as to drive the objective lens in the focusing and tilting direction. Several tracking driving units having a plurality of movable members provided therein, a plate-shaped piezo connected to the movable members so as to be driven by a potential difference so as to drive the objective lens in the tracking direction, and connected to each of the tracking driving units for tracking. A driving member is provided to transmit the driving force of the driving unit to the objective lens, and a connecting member is provided between the movable member so as to be connected to the driving member and to transmit the tracking driving force of the driving member to the objective lens.

1 is an exploded perspective view showing a conventional wire spring-supported two-dimensional actuator,

FIG. 2 is a side cross-sectional view of an operating state illustrating the focusing actuator structure of FIG. 1; FIG.

3 is a perspective view showing the circumference of the disk,

4A is a perspective view showing the configuration of an objective lens driving device for an optical pickup according to an embodiment of the present invention;

4B is a plan view of the objective lens driving apparatus of the optical pickup of FIG. 4A;

4C is a side view of the objective lens driving device of the optical pickup of FIG. 4A;

FIG. 5 is a plan view illustrating tracking driving of the objective lens driving apparatus of the optical pickup of FIG. 4B;

5 (a) is a view in which the objective lens is operated to the right,

5 (b) is a state diagram before the operation of the objective lens,

5 (c) is a view in which the objective lens is operated to the left,

FIG. 6 is a side view illustrating focusing driving of the objective lens driving apparatus of the optical pickup of FIG. 4C;

6 (a) is a view in which the objective lens is operated to the image side,

6 (b) is a state diagram of the objective lens before operation;

6 (c) is a view in which the objective lens is operated downward;

FIG. 7 is a plan view illustrating a tilting drive of the objective lens driving device of the optical pickup of FIG. 4B;

7 (a) is a view in which the objective lens is rotated in the tilting direction,

7 (b) is a state diagram of the objective lens before operation;

7 (c) is a view in which the objective lens rotates in the opposite direction,

8 is a view showing a piezo displacement principle of the present invention,

8A is a side view showing driving of the focusing direction of the piezo;

Fig. 8B is a side view showing the driving in the tracking direction of the piezo.

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

100: main body 101: lens holder

101a: objective lens 102, 102a: movable member

103, 103a: tracking drive unit 104: connecting member

105: driving member 200: piezo of movable member

300: plate-shaped piezo

Hereinafter, an objective lens driving apparatus for an optical pickup according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4A is a perspective view illustrating a configuration of an objective lens driving apparatus for an optical pickup according to an exemplary embodiment of the present invention, FIG. 4B is a plan view of the objective lens driving apparatus for the optical pickup of FIG. 4A, and FIG. 4C is a plan view of the optical pickup of FIG. 4A. 5 is a side view of the objective lens driving apparatus, and FIG. 5 is a plan view of the tracking driving of the objective lens driving apparatus of the optical pickup of FIG. 4B, and FIG. 5 (a) is a view in which the objective lens is operated to the right. (b) is a state diagram before the operation of the objective lens, Figure 5 (c) is a view in which the objective lens is operated to the left, Figure 6 is a side view of the focusing drive of the objective lens driving device of the optical pickup of Figure 4c 6 (a) is a view in which the objective lens is operated to the upper side, FIG. 6 (b) is a state diagram before the operation of the objective lens, and FIG. 6 (c) is a view in which the objective lens is operated to the lower side. 7 is an objective lens driving device for the optical pickup of FIG. 4B FIG. 7 (a) is a view in which the objective lens is rotated in the tilting direction, FIG. 7 (b) is a state diagram before the objective lens is operated, and (c) in FIG. The lens is rotated in the opposite direction, Figure 8 is a view showing the piezo displacement principle of the present invention, Figure 8a is a side view showing the driving of the piezo focusing direction, Figure 8b is a side view showing the driving of the piezo tracking direction. to be.

4 to 8, the main body 100 of the objective lens 101a driving apparatus for the optical pickup includes a lens holder 101 for fixing and supporting the objective lens 101a, and a plate-shaped piezo 300. It consists of several tracking drive units 103 and 103a, movable members 102 and 102a, a connecting member 104, and a driving member 105, and thus the focusing / tracking direction and tilting of the disc as an optical recording medium. The desired track position is detected on the disk while moving in the direction, and at the detected track position, a laser beam is incident on a Pit recorded on the disk surface, and then the reflected light is detected through an optical system, and the detected reflected light is converted into a signal. To reproduce and record the recorded contents on the disc surface.

As shown in FIGS. 8A and 8B, the principle of displacement of the piezos 200 and 300 is provided with different electrodes (voltage different in phase from AC by 180 degrees) on both sides of the piezos 200 and 300. At the same time, when the potential difference is applied to these different electrodes, one side expands, and the other side contracts to cause a certain range of displacement from the reference position, that is, a warp in a curve, so that both ends have a displacement without an angle difference.

As shown in FIG. 8A, both surfaces of the piezo 200 of the movable members 102 and 102a are made of an amorphous ceramic layer 200a, and a core material 200b is contained between the ceramic layers 200a.

The movable members 102 and 102a are formed of first and second movable members 102 and 102a, and the first and second movable members 102 and 102a are driven when the first and second movable members 102 and 102a are driven in a focusing direction. The first and second movable members 102 and 102a are connected to the sidewalls of the lens holder 101 such that the piezoelectric elements of the movable members 102 and 102a are simultaneously applied with different potentials to different electrodes. .

When the first and second movable members 102 and 102a are driven in the tilting direction, different electrodes are provided in the piezo of the first and second movable members 102 and 102a, so that the first movable member 102 has a potential difference. The first and second movable members 102 and 102a are expanded in different directions by giving a different potential difference to the second movable member 102a at the same time.

The first and second movable members 102 and 102a are connected to the tracking driving units 103 and 103a to simultaneously transfer the tracking driving force of the driving members 103 and 103a to the objective lens. The member 104 is provided.

The driving member 105 is connected to the connecting member 104 such that each of the tracking driving units 103 and 103a transmits the driving force according to the displacement due to the potential difference to the lens holder 101.

As shown in FIG. 8B, the tracking driver 103 and 103a includes first and second tracking drivers 103 and 103a, and the first and second tracking drivers 103 and 103a have a potential difference. In response, the plate-shaped piezo 300 which changes in shape only to the left and right without changing its volume is provided.

Next, an operation process of the objective lens driving apparatus for the optical pickup according to an embodiment of the present invention having the above configuration will be described in more detail with reference to FIGS. 4 to 8.

First, as shown in FIGS. 4A, B, and C, the first and second movable members 102 and 102a connected to the side wall surface of the lens holder 101 for fixing and supporting the objective lens 101a are focused in the focusing direction. As shown in (a) (b) (c) of FIG. 6, when the potential difference is simultaneously applied to the piezo 200 of the first and second movable members 102 and 102a, the first and second movable members are operated. The members 102 and 102a drive up and down together.

In addition, as shown in (a) (b) (c) of FIG. 7, when driven in the tilting direction, when the potential difference is applied to the piezo 200 of the first movable member 102, it rises after expansion to one side. At the same time, when the potential difference of the other electrode is applied to the piezo 200 of the second movable member 102a, the lens holder 101 can be driven in the tilting direction after expanding to the other side.

As such, the potential difference between the different electrodes is applied to the piezo 200 of the first and second movable members 102 and 102a according to the tilting direction of the lens holder 101, thereby driving the objective lens 101a more quickly. It can be driven finely and accurately.

In addition, as shown in (a) (b) (c) of FIG. 5, since the connecting member 104 is provided between the first and second movable members 102 and 102a when driving in the tracking direction. Since the connecting member 104 and the driving member 105 of the tracking driving unit 103 and 103a are connected to each other, the driving force of each of the tracking driving units 103 and 103a is connected through the driving member 105. The lens 104 is transferred to the lens holder 101 via the member 104.

Here, the piezo 300 of the tracking drive unit 103 (103a) is in the form of a plate, and has a plate-shaped piezo 300 which does not change in volume in response to a potential difference and changes only in left and right shapes. 1 When the potential difference is applied to the piezo 300 of the tracking driving unit 103, the piezo 300 is shifted to the left side only, while the piezo 300 of the second tracking driver 103a changes to the right side when the potential difference is given to the piezo 300. Move.

On the contrary, a potential difference is applied to the piezo 300 of the first and second tracking drivers 103 and 103a, and the objective lens 101a has the opposite left and right horizontal movements.

On the other hand, as described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

As described above, according to the objective lens driving apparatus of the optical pickup according to the present invention,

By precisely and precisely driving the lens to precisely focus the optical pickup objective on the pit, it responds and corrects quickly to the inclination angle between the objective lens and the disc to perform precise and accurate playback and recording operations, thereby providing stability of the product. And there is an effect that can improve the reliability.

Claims (2)

Several movable members having a piezo connected to a lens holder for holding and supporting the objective lens and displaced by a potential difference to drive the objective lens in the focusing and tilting directions; Several tracking driving parts having a plate-shaped piezo connected to the movable member and displaced by a potential difference to drive the objective lens in the tracking direction; A driving member connected to each of the tracking driving units and configured to transmit driving force of the tracking driving unit to the objective lens; And a connecting member is provided between the movable members so as to be connected to the driving member and to transmit a tracking driving force of the driving member to the objective lens. The method of claim 1, The piezo of the tracking driving unit is formed in a plate shape, and the plate body changes in shape only to left and right without changing its volume in response to a potential difference.