KR20010112730A - Piezoelectric Actuator for optical Pick-up Device - Google Patents

Abstract

An optical, semiconductor micro-resonator device includes a microcavity resonator (12) and a pair of adjacent waveguides (14, 16). The microactivity resonator has a curved diameter of approximately 56000*lambda.lg/n.res or less where lambda.lg is the longest operating wavelength of light and n.res is the propagating refractive index. Light propagating in the first waveguide (14) with a wavelength on resonance with the microcavity resonator is coupled to the second waveguide (16) for output therefrom. Light propagating in the first waveguide (14) with a wavelength that is off resoance with the microcavity resonator continues to propagate in the first waveguide (14) for output therefrom.

Description

Objective pick-up device for optical pickup {Piezoelectric Actuator for optical Pick-up Device}

The present invention relates to an optical lens driving apparatus for recording and reproducing on an optical disc. In particular, the tilting direction can be controlled in addition to the existing focusing and tracking directions, so that the focus of the objective lens can be controlled faster than the conventional method. The purpose is to make it possible.

In general, an optical recording / reproducing apparatus using an optical recording medium (optical disk) such as an LDP (Laser Disk Player) or a CDP (Compact Disk Player), an optical pickup that scans a light beam such as a laser onto a disk surface and detects the light beam reflected from the disk The 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 for scanning the light beam and the disk must be precisely focused, while the scanned light beam must follow the track formed on the disk precisely. Playable.

The focusing of the objective lens according to the operation of driving the objective lens is called focusing, and the movement of the objective lens along the disc track is called tracking. Therefore, the optical pickup unit drives the objective lens while focusing / tracking. There is an objective lens driving device (actuator) for performing an operation.

In such a conventional objective lens driving apparatus, the wire spring-supported two-dimensional actuator method has an objective lens 2, a tracking coil 3, and a focusing coil 4 attached to the coil holder 1 as shown in FIG. ) Is supported by several wires 5 and below which magnets 6 are attached to the yoke 7.

In this manner, the tracking coil 3 and the focusing coil 4 as shown in FIG. 2 constitute a magnetic field and a magnetic circuit generated by the magnet 6, and thus the objectives are directed in the focus control direction and the tracking control direction according to Fleming's left hand law. The lens 2 is driven up / down and left / right.

The range in which the objective lens 2 is driven in the focusing direction is ± 1 to 2 mm and about 0.3 to 0.5 mm in the tracking direction.

When the disc is reproduced with such a driving range, ± 1 μm is followed in the focusing direction and ± 0.1 μm in the tracking direction.

However, as the reproduction speed of the reproduction and recording is increased, the objective lens 2 is required to be driven faster. In particular, the reproduction of the objective lens 2 is required to drive the reproduction lens up to 40 times the speed.

In addition, the tracking direction should be driven while maintaining 10 times the accuracy of focusing. However, the conventional method has a limitation of driving the objective lens 2 quickly.

In addition, since the drive using the coil only in the magnetic field, the efficiency is lowered, and the numerical value does not exceed 50%, and the tracking driving unit and the focusing driving unit are integrated so that crosstalk occurs between each other, resulting in separation of driving. Not perfect

For this reason, an unnecessary vibration mode is caused, which lowers the stability of the reproduction and recording operations.

As another example of the objective lens actuator, the axial sliding method (rotary method) actuator method of the form as shown in FIG. 3 is constructed and used.

This method fundamentally suppresses the rotational direction vibration of the wire spring-supported two-dimensional actuator described above. The vibration is an unnecessary operation and is known to adversely affect crosstalk and jitter.

Therefore, the axial sliding type actuator method is known to show better characteristics than other methods, but this method can only reduce the inclination of the actuator itself and cannot actively compensate for the inclination of the disc. Same as the dimension actuator.

In addition, the force that causes the movement is a VCM (Voice Coil Motor) method, there is a problem that the mass of the moving part is large, which does not have a wide frequency characteristics.

The present invention is to solve such a conventional problem, it is located on both sides of the objective lens attached to the upper portion of the lens holder and fixed to the fixing member and configured to apply a voltage and then to the objective lens tracking direction by expansion and contraction By adjusting the focusing direction by means of the tracking direction piezo, which causes deformation of the warp, and fixing one end to the other end of the tracking direction piezo and the other end to the side of the lens holder to which the objective lens is attached. It is to configure the actuator consisting of a drive unit by focusing direction piezo which causes deformation of the deflection by adjusting the focal direction in the focusing direction by overshrinkage.

1 is a block diagram of a conventional wire spring-supported two-dimensional actuator.

2 is a view showing the structure of a conventional focusing actuator.

3 is a configuration diagram of a conventional axial sliding actuator.

4 is a configuration diagram of the actuator of the present invention.

5 is a front view of the actuator of the present invention.

6 is a plan view of the actuator of the present invention.

Figure 7 is a side view of the actuator of the present invention.

8 is a view showing the principle of piezo with the present invention.

Figure 9 shows the principle of piezo with the present invention.

Figure 10 is a view showing the principle of bending the S-shape of the piezo with the present invention.

11 is a view showing the principle of displacement in the shear-type piezo with the present invention.

12 illustrates a tracking operation with the present invention.

13 is a view showing a focusing operation with the present invention.

14 is a view showing a radial direction tilting operation in the present invention.

15 is a diagram illustrating a tangential direction tilting operation viewed from the side in the present invention, and (b) illustrates a tangential direction tilting operation viewed from the front side.

*** Explanation of symbols of main part of drawing ***

101: lens holder 102: objective lens

103: fixing member 104a, 104b: tracking direction piezo

105a, 105b, 105c, 105d: Focusing Direction Piezo

The objective lens driving device of the optical pickup according to the present invention will be described with reference to FIGS. 4 to 15.

In the objective lens driving apparatus of the optical pickup for converting the objective lens 102 attached to the lens holder 101 in multiple directions and recording and reproducing on the optical disk, the objective lens attached to the upper portion of the lens holder 101 Positioned on both sides of the 102 and fixed to the fixing member 103, the end is configured to apply a voltage and then the focal direction in the tracking direction of the objective lens 102 fixed to the upper portion of the lens holder 101 by expansion and contraction The lens holder having one end fixed to the other end of the tracking direction piezo 104 and the other end to which the objective lens 102 is attached. When the voltage is applied to the side of the lens 101, the focusing direction piezo 10 causes the deformation of the warp by adjusting the focal direction in the focusing direction of the objective lens 102 attached to the upper portion of the lens holder 101 by expansion and contraction. The drive part by 5) was comprised.

In addition, the tracking direction piezo 104 and the focusing direction piezo 105 allow the bending deformation in each direction to be individually performed by the applied voltage, and the tracking direction piezo 104 and the focusing direction piezo 105 ) Is designed to perform tilting control in both directions (radial and tangential) in combination with each bending deformation while bending deformation in each direction is performed separately.

According to the present invention configured as described above, the tracking operation and the focusing operation can be accurately controlled, and the tilting direction can also be controlled.

Hereinafter will be described the characteristics and operation of the configuration of the present invention.

First, in the present invention, the actuator was configured as a piezo.

This is to maintain the focus of the objective lens 102 in the focusing direction and the tracking direction more efficiently and faster than the conventional method in the information string recorded on the optical disc. In the tracking direction, two piezos 104a and 104b are employed. In addition, four piezos 105a, 105b, 105c, and 105d may be employed.

4, 5 and 6 and 7, the objective lens 102 and the lens holder 101 were integrally fixed, and then the piezos 105a, 105b, 105c, and 105d in the focusing directions were fixed to both sides by the connecting member. The focusing piezos 105a, 105b, 105c, and 105d are integrated with each other by the tracking piezos 104a and 104b having one end fixed to the fixing member 103 and the connecting member.

When the potential difference is applied to both sides of the integrated piezo as described above, one side expands and the other side contracts to drive the objective lens 102 in the focusing direction and the tracking direction by using a principle that a range of displacement occurs from the reference position. .

At this time, the driving force and the frequency response required for driving become sufficient in piezoelectric characteristics.

Due to the configuration of the present invention, the tracking operation and the focusing operation are separated from each other, which can easily cope with the focusing and tracking operation requiring no fast operation.

Here, the principle of displacement generation of the piezo constituting the actuator is as follows.

As shown in FIG. 8, when a voltage of different poles (a voltage having a phase difference of 180 ° in AC) is applied to the piezos attached to both sides, warpage occurs in a specific direction due to expansion and contraction. As shown in FIG. In case of adding the same warp, the same warp is generated, and as shown in FIG. 10, the S-shaped warp is generated and both ends have displacement without angle difference.

This applies to tracking, focusing, and tilting actuators.

Meanwhile, in the case of focusing and tilting, a shear type piezo may be used, and FIG. 11 shows an embodiment thereof. When the shear type is applied to different electrodes, the shear type acts as an actuator having a shear type.

On the other hand, the driving operation in each direction according to the present invention will be described.

First, driving in the tracking direction causes a displacement in the tracking direction when a voltage is applied to the tracking direction piezos 104a and 104b constituting the tracking actuator as shown in FIG.

In this case, the objective lens 102 and the lens holder 101 receive the operation of the tracking actuator through a focusing actuator composed of focusing piezos 105a, 105b, 105c, and 105d to perform tracking control.

The driving in the focusing direction is to operate the focusing direction piezos 105a, 105b, 105c, and 105d constituting the focusing actuator in the same direction as in FIG. 13 to obtain vertical displacement.

By applying voltages of the same phase to each of the piezos 105a, 105b, 105c, and 105d, a motion oscillating in the vertical direction can be obtained.

Accordingly, the connected objective lens 102 and the lens holder 101 can also operate without rotational movement in the vertical direction.

Then, in the radial direction, as shown in Fig. 14, the focusing direction piezos 105a, 105b, 105c, and 105d constituting the focusing actuator are selectively operated to obtain a radial direction rotational motion.

The piezoelectric 105a and 105c have the same phase and the piezo 105b and 105d have a voltage opposite to that of the piezo 105a and 105c to generate a rotational movement in the radial direction.

Accordingly, the connected objective lens 102 and the lens holder 101 may also rotate in the radial direction.

Then, the driving in the tangential direction selectively operates the piezos 105a, 105b, 105c, and 105d constituting the focusing actuator as in FIGS. 15A and 15B to obtain a tangential direction rotational motion.

The same phase as the piezos 105a and 105b is applied to the piezos 105a and 105d.

By applying a voltage of a phase opposite to 105b), a rotational movement in the tangential direction is generated.

Accordingly, the connected objective lens 102 and the lens holder 101 may also rotate in the tangential direction.

When the directional motion is combined, the tracking actuator is completely separated from the focusing actuator and the tilting actuator, so that it can be controlled completely separately.

However, since focusing and tilting use the same actuator, the driving voltage is simply inputted by overlapping each direction input value (voltage) during control.

As described above, the present invention constitutes an actuator using a piezo, so that the tracking operation and the focusing operation are clearly distinguished and driven, and evenly selected in a wide band, especially in both directions (radial and tangential). Tilting control of is possible.

As a result, the objective lens high-speed driving required for the increase in the speed of reproduction and recording is realized, so that the focus of the objective lens can be controlled faster than the conventional method.

Claims (5)

An optical pickup objective lens driving apparatus for converting an objective lens attached to a coil holder in multiple directions and recording and reproducing on an optical disc, It is located on both sides of the objective lens attached to the upper portion of the lens holder and fixed at one end to the fixing member to adjust the focusing direction in the tracking direction by the expansion and contraction of the tracking direction piezo and causing deformation of the warp and , One end is fixed to the other end of the tracking direction piezo and the other end is fixed to the side of the lens holder to which the objective lens is attached to adjust the focal direction in the focusing direction by inflation and contraction to cause deformation of warpage. The objective lens driving apparatus of the optical pickup, characterized by having a focusing direction piezo. The method of claim 1, And the tracking direction piezo and the focusing direction piezo are configured such that the bending deformation in each direction is individually displayed by the voltage applied thereto. The method of claim 1, The tracking direction piezo and the focusing direction piezo are configured to perform tilting control in both directions (radial and tangential) in combination with each bending deformation while bending deformation in each direction is individually performed. Objective lens drive device. The method of claim 1, The tracking direction piezo is fixed to one end of each of the fixing member, the objective lens driving apparatus of the optical pickup, characterized in that composed of two. The method of claim 1, The focusing direction piezo is fixed to the other end of the fixing member and the other end is fixed to the lens holder, respectively, characterized in that the objective lens driving device of the optical pickup.