KR101408167B1 - method of operating a collimating lens, and optical pickup and disc drive adopting the method - Google Patents

Abstract

Disclosed are a method for buffering a shock according to an operation of a collimating lens, and an optical pickup device and an optical disk drive adopting the same. A method for driving the collimating lens comprises a position adjustment step of adjusting a position of the collimating lens, installed on an optical axis between a laser diode and an object lens of the optical pickup device, at non-linear speed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a collimating lens driving method, and an optical pickup apparatus and an optical disk drive employing the same,

The present invention relates to a method of driving a collimating lens and an optical pickup device and an optical disc drive to which the present invention is applied.

The optical disc drive corresponding to the multimedia object is designed to use not only a conventional compact disc (CD) but also a digital versatile disc (DVD) and a BD (Blu-ray Disc), for example.

In general, an optical system of a multi-media compatible optical pickup device is provided with an objective lens corresponding to a CD / DVD and an objective lens corresponding to a BD. In addition, a beam splitter, a collimating lens and a mirror are separately provided. This is because, due to the nature of the optical system structure, the optical distances of the optical system corresponding to the CD / DVD and the optical system corresponding to the BD are different from each other, and thus the optical distance required for each optical system must be secured in collecting the optical system in one structure to be.

Therefore, the conventional optical pickup device for multi-media has a structure in which an independent optical system corresponding to CD / DVD and an independent optical system corresponding to BD are simply integrated into one structure.

This optical pickup apparatus has a region shared by the CD / DVD optical system and the BD optical system, which is the optical path between the beam splitter and the objective lens in which the beam for CD / DVD and the beam for BD are combined. A collimating lens is placed on the light path, which is used to adjust the optical distance for each medium and for each layer of the medium. This collimating lens moves on the optical axis by the stepping motor. When this stepping motor is operated, a mechanical shock is generated. Such an impact affects the objective lens driving system, resulting in a delay in focusing operation and tracking operation.

The present invention provides a driving method of a collimating lens capable of reducing a mechanical impact caused by operation of a collimating lens, and an optical pickup device and an optical disk drive to which the collimating lens is applied.

A method of driving a collimating lens according to the present invention comprises:

And a position adjusting step of adjusting the position of the collimating lens provided on the optical axis between the laser diode and the objective lens of the optical pickup device at a nonlinear velocity.

In the driving method of a collimating lens according to a preferred embodiment of the present invention, in the position adjusting step, the nonlinear velocity includes an initial acceleration period and a deceleration period after the acceleration period.

The method of driving a collimating lens according to another embodiment of the present invention may further include a constant velocity section between the acceleration section and the deceleration section in the position adjustment step.

According to still another embodiment of the present invention, the driving method of a collimating lens may drive the collimating lens by a stepping motor having a lead screw.

An optical pickup apparatus according to the present invention includes:

Laser diode;

An objective lens focusing the laser beam from the laser diode on an optical disk;

A collimating lens provided on an optical axis between the laser diode and the objective lens; And,

And a motor for moving the collimating lens at a nonlinear velocity on the optical axis.

An optical disc drive according to the present invention comprises:

A laser diode for generating a laser beam, an objective lens for concentrating the laser beam on an optical disk, and a collimating lens for optically controlling the laser beam located on the optical axis therebetween, the collimating lens at a non- An optical pickup device having an actuator for moving the optical pickup;

A circuit unit for driving the optical pick-up apparatus and processing information therefrom; Respectively.

According to the present invention, it is possible to drive the collimating lens at a nonlinear velocity, thereby alleviating the shock caused by the sudden operation of the collimating lens. According to such shock mitigation, the lead-in time and the seek stability of the optical pickup apparatus can be improved. Also, deterioration of reproduction and recording quality caused by so-called step loss due to a sudden impact can be suppressed.

1A is a schematic configuration diagram of an optical pickup device according to an embodiment of the present invention.
1B is a schematic perspective view of a collimating lens assembly applied to an optical pickup device according to an embodiment of the present invention.
2 is a block diagram illustrating a schematic configuration of an optical disc drive according to an embodiment of the present invention.
FIG. 3 illustrates a change in position of a collimating lens for each medium in the optical pickup device according to an embodiment of the present invention.
4 shows a layered structure of media having a plurality of layers.
FIG. 5 shows a change in the transport speed of the collimating lens according to the driving method of the collimating lens according to the present invention.
6 shows a waveform of an actuator driving pulse according to a driving method of a conventional collimating lens.
6 shows waveforms of actuator driving pulses in a driving method of a collimating lens according to the present invention.

Hereinafter, a driving method of a collimating lens according to the present invention and an optical pickup apparatus and an optical disc drive according to the present invention will be described with reference to the accompanying drawings.

FIG. 1A is a structural view showing a schematic structure of an optical pickup apparatus according to an embodiment, and FIG. 1B shows a driving system of a collimating lens applied to an optical pickup apparatus according to the present invention. 1A, an optical pickup apparatus mainly includes an optical transmission system (or transmission system) 20 directly corresponding to a medium 1 such as a CD / DVD or a DB, And a light receiving system 10 for receiving the light reflected from the medium 1 for reproducing information and generating an electric reproduction signal.

Specifically, the light source system 10 includes a first light source 11a for a CD / DVD and a second light source 11 for a BD. A CD / DVD diffraction element 12a and a BD diffraction element 12b are provided in front of the first light source 11a and the second light source 11b. The two diffraction elements 12a and 12b diffract the laser beam from each of the light sources 11a and 11b by the diffraction effect to form the main beam and the +/- primary sub beams. The laser beam from the first light source 11a and the second light source 11b is led to the light emitting system 20.

The light emitting system 20 includes a beam splitter 21 for determining the traveling direction of the laser beam, a collimating lens 22 for correcting the spherical aberration caused by the change of the type of the medium and the access layer of the medium, And an objective lens 24 for concentrating the laser beam from the system 10 onto the medium 1. The collimating lens 22 adjusts the laser beam flux while moving along the optical axis to correct aberration of a number of laser beam spots formed on the medium 1. [ The actuator 23 is coupled to the collimating lens 22. Most of the actuators 23 are step motors. The stepper motor actuator includes a lead screw 23a. The lead screw 23a is coupled to the transfer portion 22a provided on one side of the collimating lens 22 so that the transfer portion 22a corresponds to the rotation of the lead screw 23a, And is reciprocated along the axis. 1B is a schematic perspective view of a collimating lens assembly including the collimating lens 22 and the actuator 23 driving it. As shown in Fig. 1B, the collimating lens 22 is coupled to the transfer section 22a in the form of a frame. The transfer section 22a has a portion 22a 'to which the collimating lens 22 is mounted and a portion 22a "to be engaged with the leadscrew 23a of the actuator 23. When the leadscrew 23a is mounted The portion 22a '' is engaged with the lead skew 23a so as to move along the axial direction of the lead screw in accordance with the rotation of the lead screw 23a so that the collimating lens 22 also moves along the optical axis And transport it accordingly. Guide shafts 22b and 22c for guiding the conveyance of the conveyance portion 22a are provided on both sides of the conveyance portion 22a and a buffer spring 22b for elastically pressing the conveyance portion 22a in one direction is provided on one guide shaft 22c. (22d).

1A, the photodetector 30 includes a photodetector 31 for receiving a laser beam from the medium 1 incident through the beam splitter 21, and a photodetector 31 for focusing the laser beam on the photodetector 31 in an appropriate size (Not shown). Here, the beam splitter 21 in the light emitting system 20 directs the laser beam from the light source system 10 to the objective lens 24, and the light reflected from the medium 1 passes through the light receiving system 30 .

The optical pickup device as described above is included as an element of the optical disc drive and may be included in the optical disc drive 100 having the structure as shown in FIG.

The optical disc drive 100 includes an optical pickup device 2 for reading or writing information from the medium 1, for example, an optical pickup device as shown in FIG. 1A. The optical pickup device 2 further includes an optical system of the optical pickup device as described above, and a mechanical system 2a mechanically supporting such an optical system and causing the focusing and tracking operations of the objective lens. The light receiving element 31 of the optical system is electrically connected to a front end part IC 4 including an RF amplifier and the like and the light sources 11a and 11b are connected to a light source driver (or a laser diode driver, LDD 6) . The light source driver 6 is connected to an HFM circuit 7 which provides a high frequency modulation component. On the other hand, the mechanical system 2a of the optical pickup device 2 is connected to the servo unit 5. The servo unit 5 performs tracking and focusing control of the optical pickup device 2, position control of a collimating lens, and the like. The front end part 4, the servo unit 5, the light source driver 6 and the HFM circuit 7 are connected to a DSP (Digital Signal Processor) 3. The DSP 3 includes an information processing section 3a including a decoder / encoder for processing signals from the front end part 4 and the like such as the servo section 5, the light source driver 6 and the HFM circuit 7 And a system control unit 3b for controlling (controlling) all the elements inside the system of the system.

The position control of the collimating lens 22 by the servo unit 5 uses an actuator 23 such as the step motor as described above.

3 illustrates the position of a collimating lens for each medium such as a CD, a DVD, and a BD. The collimating lens 102 is located on the reflected light path from the beam splitter 103, that is, on the optical axis of the optical transmission system. In FIG. 3, 'B' represents the position corresponding to the BD having a thickness of 0.0875 mm as an initial position of the collimating lens. And 'A' is a position corresponding to the first layer (L0) of the BD. And 'C' is the DVD, 'D' is the CD, and 'E' is the corresponding location of the second layer (L1) of the BD. In this way, depending on the type of media or the same medium, if the layers are different, the collimating lens must be moved to a given position.

Figure 4 illustrates a multi-layered media with a laminated structure. It is possible to have two layers (L0 and L1) of the medium or three layers (L0, L1 and L2) or four layers (L0, L1, L2 and L3). As in one type of medium, it is thus possible to have multiple layers, and therefore it is necessary to compensate for the spherical aberration of the beam spot focusing on each layer using a collimating lens.

Table 1 below shows the number of steps (number of revolutions) of the lead screw of the stepping motor for moving the collimating lens by the layers (L0 to L3) of the BD having the three-layer (TL) and four-layer (QL) structure. The moving distance of the collimating lens per one step of the illustrated stepping motor is 12.5 占 퐉.

L0 L1 L2 L3 BD QL 36 85 148 189 BD TL 36 115 176

In the conventional method of correcting the spherical aberration using the collimating lens, the moving speed of the collimating lens 22 by the actuator 23 is set at a constant speed, And the impact caused by rapid stopping and rapid stopping occurred. The impact due to the above-described causes affects the objective lens driving system, resulting in a delay in focusing operation and tracking operation.

The driving method of the collimating lens according to the present invention applies a non-linear motion velocity without applying the constant velocity motion causing the above-described problems. That is, as shown in FIG. 5, the driving method of the collimating lens according to the present invention includes an acceleration period and an acceleration period. That is, the speed is gradually increased to reduce the impact due to rapid maneuver when the initial actuator is started, and the speed is gradually decreased from the target position. According to the speed increase and the speed reduction, it is possible to effectively reduce the impact caused by the rapid start and stop of the actuator or the collimating lens. In the present invention, a constant velocity section can be provided between the acceleration section and the deceleration section. This is advantageous in that the moving distance is long or the impact due to the transition from the acceleration section to the deceleration section is reduced.

6 and 7 show drive voltage pulses applied to the stepper motor as an actuator.

Fig. 6 shows that the same pulse width is maintained between the actuator driving ranges. This is in accordance with a conventional method of driving a collimating lens that moves at a constant speed.

FIG. 7 shows a method of driving a collimating lens according to the present invention, in which the pulse width is changed from the start to the stop. That is, initially, the pulse width of the driving voltage is wide, gradually becoming narrower, and the pulse width is gradually widening before reaching the final stoppage. Here, the wider the pulse width, the lower the speed, the narrower the speed is. Accordingly, the acceleration of the pulse width gradually decreases, and the deceleration of the pulse width becomes larger.

The present invention mitigates the impact when the actuator starts to move the collimating lens through the above-described method. To this end, it is possible to drive the collimating lens at a nonlinear velocity to alleviate the shock caused by the sudden operation of the collimating lens, and to improve the lead-in time and seek stability of the optical pickup device through such shock mitigation. In addition, it is possible to prevent step loss such as so-called mechanical locking or demage due to a sudden impact, thereby suppressing deterioration of reproduction and recording quality.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (14)

And a position adjustment step of adjusting, at a nonlinear velocity, the position of the collimating lens provided on the optical axis between the laser diode and the objective lens of the optical pickup device,
Wherein the nonlinear velocity includes an initial acceleration period and a deceleration period after the acceleration period. delete The method according to claim 1,
Wherein the position adjusting step further includes a constant velocity section between the acceleration section and the deceleration section. The method according to claim 1 or 3,
Wherein the collimating lens is driven by a step motor having a lead screw. Laser diode;
An objective lens focusing the laser beam from the laser diode on an optical disk;
A collimating lens provided on an optical axis between the laser diode and the objective lens; And,
And an actuator for moving the collimating lens at a nonlinear velocity including an initial acceleration section and a deceleration section after the acceleration section on the optical axis. delete 6. The method of claim 5,
Wherein the nonlinear velocity further includes a constant velocity section between the acceleration section and the deceleration section. The method according to claim 5 or 7,
Wherein the actuator is a stepping motor. An objective lens for concentrating the laser beam on an optical disk, a collimating lens positioned on an optical axis between the laser diodes and optically controlling the laser beam, a collimating lens for focusing the collimating lens on an initial acceleration section And a motor that moves at a nonlinear velocity including a deceleration section after the acceleration section; And
And a circuit section for driving the optical pick-up apparatus and processing information therefrom. delete 10. The method of claim 9,
Wherein the nonlinear velocity further comprises a constant velocity section between the acceleration section and the deceleration section. The method according to claim 9 or 11,
Wherein the motor applies a stepping motor. 13. The method of claim 12,
Wherein the optical pickup apparatus has a CD / DVD and BD compatible structure. The method according to claim 9 or 11,
Wherein the optical pickup apparatus has a CD / DVD and BD compatible structure.

Images