JP2014182841A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk drive having no position detection sensor capable of reliably performing step-out detection of a spherical aberration correction mechanism.SOLUTION: The optical disk drive includes having a spherical aberration correction mechanism includes a controller that, when the drive frequency of a stepping motor which drives the spherical aberration correction mechanism is not identical to the frequency of a tracking error signal, or when the amplitude of the tracking error signal is identical to a predetermined threshold value or smaller, determines a step-out has occurred; and when the drive frequency of the stepping motor which drives the spherical aberration correction mechanism is identical to the frequency of the tracking error signal and when the amplitude of the tracking error signal is larger than the predetermined threshold value, determines the step-out has not occurred.

Description

  Embodiments described herein relate generally to an optical disc apparatus that performs step-out detection and recovery processing by a spherical aberration correction mechanism.

  In an optical disc apparatus, spherical aberration is caused by the thickness error of the protective layer that varies from one optical disc to another. For example, a beam expander is used as a spherical aberration correction means to adjust the light diameter. For adjusting the spherical aberration, the spherical aberration correcting means is controlled so that the signal quality of the reflected light obtained from the optical disk is appropriate.

  In the light diameter adjustment using the beam expander, the light diameter adjusting lens is moved by the stepping motor, and the rotation angle is controlled by the number of pulses applied to the stepping motor. The lead screw provided on the rotating shaft of the stepping motor converts the rotary motion into a linear motion and controls the position of the light diameter adjusting lens.

  In a moving mechanism using a stepping motor, the problem is that the rotor moves to the next magnetic stable point and the step-out in which the correspondence between the number of applied pulses and the actual rotation angle cannot be achieved.

  If a step-out occurs during the movement of the spherical aberration correction lens, an error occurs between the adjusted position of the spherical aberration correction lens and the actual target position even if a predetermined number of pulses are applied to the stepping motor.

  In some optical disk devices, after loading an optical disk, first, the presence or absence of step-out is confirmed. However, there is a method using a position detection sensor as a step-out detection method. This is because in the loading process when loading an optical disc, the position detection sensor is used to move the spherical aberration correction lens to the reference position to perform aberration correction / adjustment. After the loading is completed, the position detection sensor is used again. The spherical aberration correction lens is moved to the reference position.

  Specifically, step-out detection is performed based on whether or not the position detection sensor can detect when the stepping motor is rotated in the reverse direction of the same number of steps after a predetermined number of pulses have been moved with reference to the position of the position detection sensor.

  While step-out detection using a position detection sensor enables accurate positioning, the position detection sensor and its peripheral components increase, leading to an increase in cost.

  Therefore, when the position detection sensor is not used, the driving torque is set so as not to step out. However, there are cases where excessive driving torque may occur due to variations in the mechanism, and there is a problem that step-out detection cannot be performed due to noise in the optical signal.

JP 2011-28803 A JP 2009-289344 A

  The problem to be solved by the present invention is to provide an optical disc apparatus that can reliably detect the step-out of the spherical aberration correction mechanism when a position detection sensor is not provided.

  The optical disc device of the embodiment is an optical disc device provided with a spherical aberration correction mechanism, and the driving frequency of the stepping motor that drives the spherical aberration correction mechanism and the frequency of the tracking error signal are not equal, or the tracking error signal If the amplitude is equal to or smaller than a predetermined threshold, it is determined that a step-out has occurred, the driving frequency of the stepping motor that drives the spherical aberration correction mechanism is equal to the frequency of the tracking error signal, and And a control unit that determines that the step-out has not occurred when the amplitude of the tracking error signal is larger than a predetermined threshold value.

1 is a schematic view showing an overall arrangement of an optical disc apparatus according to an embodiment of the present invention. 5 is a flowchart showing a flow of step-out detection / recovery processing in the optical disc device according to the present embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of an optical disc apparatus according to an embodiment of the present invention. As shown in FIG. 1, in the optical disc apparatus 100, the optical disc 1 is rotated by a spindle motor 2 and a driver circuit 3. The light emitted from the laser diode 5 mounted on the optical pickup unit 4 passes through the beam splitter 6 and the spherical aberration correction mechanism 7 and is condensed on the data recording surface on the optical disc 1 by the objective lens 8.

  Then, the light condensed on the optical disk 1 is reflected by the data recording surface, and the reflected light passes through the objective lens 8, the spherical aberration correction mechanism 7, and the beam splitter 6 again, enters the light receiving element 9, and is converted into an electric signal. Is done. An electrical signal output from the light receiving element 9 is input to the control unit 10. The control unit 10 processes the input signal, communicates with an externally connected device through the interface 11, and feeds back to the driver circuit 3 to control the spindle motor 2, the optical pickup unit 4, and the stepping motor 12. . The controller 10 also controls the spherical aberration correction mechanism 7 as will be described later.

  In this embodiment, step-out detection is performed using a feedback signal to a control signal when the spherical aberration correction mechanism is driven.

<Step-out detection / recovery processing>
Next, the flow of the step-out detection process in the optical disc apparatus configured as described above will be described. FIG. 2 is a flowchart showing a flow of step-out detection / recovery processing in the optical disc apparatus according to the present embodiment.

  First, the reference position of the spherical aberration correction mechanism is determined (step S21). The reference position is determined by moving the spherical aberration correction lens to the movement limit of the spherical aberration correction mechanism with a predetermined number of pulses with respect to the reference movement limit position. For example, it is also preferable to set the chassis inside the pickup mechanism as the reference position. In this case, the position is fixed by moving the spherical aberration correction mechanism to a position where it abuts against the chassis.

  After the determination of the reference position, the value of the pulse counter at the reference position is set to zero, and the number of pulses applied to the stepping motor 12 is managed. The value of the pulse counter at the optimum position of the spherical aberration correction lens after the spherical aberration correction adjustment is recorded, and thereafter, the spherical aberration correction lens is positioned based on the number of applied pulses with reference to the value of the pulse counter.

  Next, the servomotor is turned on, and the focus adjustment for positioning the light spot on the predetermined reproduction surface and the tracking adjustment state for positioning the light spot on the predetermined track are set (step S22).

  Next, the drive frequency of the stepping motor 12 that drives the spherical aberration correction lens is set (step S23).

  Next, the driving amount of the stepping motor represented by the number of pulses is set (step S24). The amount of driving here is set according to the target position, such as driving to the reference position, or it is also set according to the state, such as driving during fine adjustment to adjust the spherical aberration correction position. To do.

  Next, the spherical aberration correction mechanism is driven based on the set drive amount (step S25).

  When the spherical aberration correction mechanism is driven, a feedback signal is detected as the tracking error signal. This feedback signal is a signal synchronized with the driving frequency of the spherical aberration correction mechanism, and can be distinguished from other signals.

  The tracking error signal is a signal in which an error generated between the pits on the optical disk and the laser beam is detected, and is generated by adding and amplifying the signal output from the pickup.

  In parallel with the driving of the spherical aberration correction mechanism, the amplitude and the track crossing frequency of the tracking error signal are monitored (step S26). In order to stably follow (track) the laser beam to the pit, the tracking servo is stabilized by adjusting the amplification amount so that the target tracking error signal amplitude can be obtained. The frequency of the tracking error signal can be obtained from the track crossing period. Here, the reason why the amplitude value of the tracking error signal is checked is to eliminate the influence of noise and prevent erroneous determination when checking the frequency of the detected tracking error signal.

  Next, it is determined whether or not the driving frequency of the spherical aberration correction mechanism is equal to the frequency of the tracking error signal and the amplitude of the tracking error signal is larger than a predetermined threshold (step S27).

  Here, the threshold is preferably set to ± 50% of the amplitude of the target tracking error signal, for example. That is, the threshold value is set in a range of 0.5 × (amplitude of target tracking error signal) to 1.5 × (amplitude of target tracking error signal). The amplitude of the actual tracking error signal and the feedback signal at the time of spherical aberration correction driving used for the step-out detection are measured by being amplified. Therefore, the value is close to the target tracking error signal amplitude. However, it is set as described above in consideration of a change in the amount of signal amplification due to a temperature change and variations in adjustment accuracy.

  If Yes in step S27, it is determined that no step-out has occurred and the spherical aberration correction mechanism is operating normally, the spherical aberration correction is continued (step S28), and the step-out detection / recovery process is terminated. .

  On the other hand, if No in step S27, a step-out has occurred, so a recovery process from the step-out is performed.

  In the recovery process from the step-out, first, the drive frequency of the recovery spherical aberration correction mechanism is set (step S29). Here, the recovery drive frequency is set to a value smaller than the drive frequency set in step S23 in order to escape from the step-out state. This is because the higher the frequency, the faster the moving speed and the lower the driving torque. For example, a reduction of 20% is preferable.

  Next, after the spherical aberration correction mechanism is moved to the reference position (step S30), the process proceeds to step S24. The reference position is as described above.

  According to the present embodiment, even when the position detection sensor is not provided, the step-out detection of the spherical aberration correction mechanism can be reliably performed.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Spindle motor 3 ... Driver circuit 4 ... Optical pick-up unit 5 ... Laser diode 6 ... Beam splitter 7 ... Spherical aberration correction mechanism 8 ... Objective lens DESCRIPTION OF SYMBOLS 9 ... Light receiving element 10 ... Control part 11 ... Interface 12 ... Stepping motor 100 ... Optical disk apparatus

Claims (7)

An optical disc apparatus having a spherical aberration correction mechanism,
An optical disc apparatus comprising: a control unit that detects a step-out using a feedback signal to a control signal when driving the spherical aberration correction mechanism.   The optical disc apparatus according to claim 1, wherein the control signal is a tracking error signal.   The optical disk apparatus according to claim 1, wherein the feedback signal is a signal synchronized with a driving frequency of the spherical aberration correction mechanism. An optical disc apparatus having a spherical aberration correction mechanism,
If the drive frequency of the stepping motor that drives the spherical aberration correction mechanism and the frequency of the tracking error signal are not equal, or if the amplitude of the tracking error signal is equal to or smaller than a predetermined threshold, a step-out occurs. It is determined that
If the driving frequency of the stepping motor that drives the spherical aberration correction mechanism and the frequency of the tracking error signal are equal, and the amplitude of the tracking error signal is greater than a predetermined threshold, it is determined that no step-out has occurred. An optical disc device including a control unit.   5. The optical disc apparatus according to claim 4, wherein the threshold value is set in a range of ± 50% of a target tracking error signal amplitude.   When determining that the step-out has occurred, set the recovery drive frequency to be lower than the drive frequency of the stepping motor, move the spherical aberration correction mechanism to the reference position, and then again 6. The optical disk apparatus according to claim 4, wherein a driving amount of the stepping motor is set.   The optical disk apparatus according to claim 6, wherein the reference position is set to a position where a chassis inside the pickup mechanism abuts.

Images