JP2004152353A - Disk drive and servo method of disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk drive capable of realizing the stable servo by reducing the influence of the external disturbance. <P>SOLUTION: This disk drive includes a linear controller 5A for outputting a normal time control signal 5aS for the linear control, an oscillating time controller 8A for outputting an oscillating time control signal 8aS for the sliding mode control, an oscillation detector 9 for determining whether the oscillation is generated or not, and a changeover switch 12. When no oscillation exists, the normal time control signal 5aS is selected by the changeover switch 12 to drive a pickup 3. When the oscillation is generated, the oscillation time control signal 8aS is selected by the changeover switch 12 to drive the pickup 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
1. Field of the Invention The present invention relates to a disk drive device capable of realizing a servo in consideration of the influence of disturbance and a servo method therefor.
[0002]
[Prior art]
2. Description of the Related Art In a disk device such as a CD and a DVD, an operation of reading data spirally arranged on a rotating disk is performed by a laser beam output from a pickup. In the operation, focus control for adjusting the focus of the laser beam output from the pickup to data on the track and tracking control for determining the pickup at a predetermined track position on the disk are performed.
[0003]
In focus control, the amount of deviation of the pickup from the focal point is generally detected by the astigmatism method. In the astigmatism method, laser light output from a laser diode and reflected back to a disk is input to a four-divided detector through a condenser lens and a kamaboko-shaped cylindrical lens. Since astigmatism is generated by the condenser lens and the semi-cylindrical cylindrical lens, the input to the quadrant detector becomes a perfect circle when in focus and an ellipse when out of focus. Therefore, if the outputs of the diagonals of the quadrant detector are added and the difference between the addition results is taken, the output becomes "0" when the focus is achieved, and an output proportional to the amount is generated when the focus is lost. The output is used as a signal for determining the position of the pickup in the focus direction (hereinafter, referred to as a focus error signal), and focus control is performed so that the value of the focus error signal becomes “0”. In this control, if the focus is too out of focus, the laser light will not be focused on the quadrant detector, so that a normal focus error signal cannot be detected.
[0004]
FIG. 5 is a diagram showing a focus error signal.
[0005]
In the focus control, as shown in the figure, if a vibration occurs and the pickup goes out of the focus area, a normal focus error signal cannot be detected. Therefore, it is necessary to drive the pickup in the focus direction by the open control, move the pickup to a focus region where a normal focus error signal can be detected, and perform an operation for enabling the focus control, and the operation deviates from the focus region. During this time, the servo is off and data on the disk cannot be read or written.
[0006]
On the other hand, in tracking control, in general, a deviation amount from a center track is detected by using a sub spot in addition to a main spot for detecting a tracking error signal by a three spot method. When the pickup is on the furnishing center track, the two laser beams reflected off the disc and returned through the two sub-spots will be furnished to the same detected intensity. Then, when the pickup is displaced from the center track, the amount of displacement from the center track is detected by a difference in the detection intensity of the two laser beams. However, if the pickup is too far from the center track and is located on an off-track without a track, a normal tracking error signal cannot be detected.
[0007]
FIG. 6 shows a tracking error signal.
[0008]
In the tracking control, as shown in the figure, when vibration occurs and the pickup comes on the off-track, the number of tracks crossed by the vibration is counted, and on the track (on-track) from which the pickup was derived by the access control. The servo must be turned off while on the off-track and data cannot be read or written on the disk.
[0009]
In order to prevent the servo from deviating in this way, if the influence of disturbance acts strongly, such as when vibration occurs, conventionally, a method of increasing the gain of the controller during normal servo operation is performed. was there.
[0010]
FIG. 7 is a diagram showing a configuration of a conventional disk drive device.
[0011]
The disk drive device shown in FIG. 7 includes a disk 101, a spindle motor 102, a pickup 103, a head amplifier 104, a controller 107, a vibration amplifier 108, a vibration detector 109, a vibration gain switch 110, and a pickup for driving the pickup. A drive driver 111 is provided. In the figure, 50S indicates various read signals, and 40S indicates a position error signal.
[0012]
In the disk drive device shown in FIG. 7, the disk 101 is rotated by a spindle motor 102, the disk 101 has a spirally written track, and data on the track is read by a laser beam output from the pickup 103. During normal operation without vibration, the vibration-time gain changeover switch 110 is connected to the controller 107 side, and the controller 107 generates and outputs a pickup drive signal based on the position error signal 40S. The pickup 103 is driven.
[0013]
When vibration occurs, the vibration gain changeover switch 110 switches the connection to the vibration amplifier 108 side. Therefore, the pickup drive signal generated by the controller 107 is amplified and output by the vibration amplifier 108, and the pickup drive driver 111 drives the pickup 103.
[0014]
Thus, the influence of disturbance can be reduced by the pickup drive signal amplified during vibration.
[0015]
[Non-patent document 1]
Kenzo Nonami and Hiroki Tada, "Sliding mode control"
[0016]
[Problems to be solved by the invention]
However, as shown in FIG. 8, the open loop gain of the control system is amplified in the entire frequency characteristic band, and the gain in the frequency band near the resonance point of the pickup is also amplified. As a result, the control system becomes rather unstable, and the pickup becomes oscillating, making it impossible to read or write data on the disk.
[0017]
Further, in the conventional disk drive device, control with good tracking performance is realized by using linear control such as PID control and state feedback control. However, when the linear control is used, there is a case where it is not enough to suppress the influence of disturbance at the time of vibration or after accessing a target track.
[0018]
On the other hand, when sliding mode control is used as a strong control system against disturbances and uncertain factors, the phase state of the controlled object is constrained to the designed switching (plane) using the switching action, The variable is made to converge to “0”. However, chattering may occur in the control output due to the switching action.
[0019]
Therefore, an object of the present invention is to provide a disk drive device capable of reducing the influence of disturbance and realizing stable servo.
[0020]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, first, a disk drive device according to claim 1 of the present invention provides a disk drive that performs at least one of focus servo and tracking servo based on an output signal from a pickup. In a drive device, a pickup drive unit that outputs a signal for driving the pickup, and a normal control signal that performs a normal control signal for performing linear control on the pickup drive unit based on the output signal from the pickup Time control means, vibration control means for outputting a vibration control signal for performing a sliding mode control to the pickup driving means based on the output signal from the pickup, and the output signal from the pickup. Based on the disk drive Vibration detecting means for determining whether or not vibration has occurred, and outputting a vibration detection signal; and any one of the normal control signal and the vibration control signal based on the vibration detection signal from the vibration detection means. Selecting means for selecting the normal control signal when the vibration detecting means determines that no vibration has occurred in the disk drive device. The pickup driving means outputs a signal for driving the pickup in response to the normal control signal, and when the vibration detecting means determines that vibration has occurred in the disk drive device, The selecting means selects the vibration control signal, and the pickup driving means controls the pick-up in accordance with the vibration control signal. Tsu those and outputs a signal for driving the flop.
[0021]
According to the first aspect of the present invention, the linear control is used for the servo during the normal operation where no vibration is generated, and the sliding mode control is used for the servo when the vibration is generated. It is possible to provide a disk drive device capable of realizing high stability by a disturbance suppression effect of mode control.
[0022]
According to a second aspect of the present invention, in the disk drive device according to the first aspect, the vibration detection means determines whether or not vibration has occurred in the disk drive device based on an RF signal output from the pickup. It is to be judged.
[0023]
According to a third aspect of the present invention, in the disk drive device according to the first aspect, the vibration detecting means generates a vibration in the disk drive device based on a focus error signal or a tracking error signal output from the pickup. It is determined whether or not it has occurred.
[0024]
According to a fourth aspect of the present invention, in the disk drive device according to any one of the first to third aspects, based on the focus error signal or the tracking error signal output from the pickup, the focus error signal or the focus error signal thereof is output. When the value of the tracking error signal becomes close to 0, or when the focus error signal or the tracking error signal comes near a predetermined switching line (plane) to the sliding mode control, the vibration of the selecting means is reduced. It is further provided with switching timing determining means for outputting a switching timing signal for selecting a control signal, wherein the selecting means, when receiving the switching timing signal, selects the vibration control signal.
[0025]
According to the fourth aspect of the present invention, the switching to the sliding mode control is performed at a timing based on the error signal. Therefore, the chattering effect that occurs when switching to the sliding mode control can be reduced, and the switching can be performed smoothly.
[0026]
Secondly, in order to solve the above problem, a disk drive device according to a fifth aspect of the present invention is a disk drive device that performs tracking servo based on a tracking error signal from the pickup. Pickup driving means for outputting a signal to be driven; access control means for outputting an access control signal for moving the pickup to a target track based on the tracking error signal from the pickup; and Based on a tracking error signal, a pull-in control means for outputting a pull-in control signal for performing a sliding mode control to the pickup driving means, and the access control signal based on an output signal from the pickup. Selecting means for selecting any one of a control signal at the time of retraction, and after the pickup has moved to a target track based on the access control signal from the access control means, the selecting means includes A time control signal, and the pickup driving means outputs a signal for driving the pickup according to the pull-in control signal.
[0027]
According to the fifth aspect of the present invention, since the sliding mode control is used for the servo after the pickup is moved to the target track, it is possible to provide a disk drive device capable of realizing high stability by a disturbance suppressing effect.
[0028]
According to a sixth aspect of the present invention, in the disk drive device according to the fifth aspect, when the tracking error signal comes near a switching line (plane) to a predetermined sliding mode control based on the tracking error signal. And a switching timing determining means for outputting a switching timing signal for causing the selecting means to select the pull-in control signal, wherein the selecting means, upon receiving the switching timing signal, selects the pull-in control signal. Shall be.
[0029]
According to the sixth aspect of the present invention, since the switching to the sliding mode control is performed at a timing based on the error signal, the chattering effect that occurs when switching to the sliding mode control can be reduced, and the switching can be performed smoothly.
[0030]
Thirdly, in order to solve the above problem, a servo method for a disk drive device according to claim 7 of the present invention provides a servo method for a disk drive device which performs at least one of focus servo and tracking servo. The method, when performing a normal operation in which no vibration occurs in the disk drive device, drive the pickup using linear control, perform the focus servo or the tracking servo, the disk drive device When vibration is generated, the pickup is driven by using sliding mode control to perform the focus servo or the tracking servo.
[0031]
According to the seventh aspect of the present invention, linear control is used for servo during normal operation without vibration, and sliding mode control is used for servo when vibration is generated. Therefore, high tracking and sliding by linear control are used. A servo method for a disk drive device capable of realizing high stability by a disturbance suppression effect of mode control can be provided.
[0032]
Fourthly, in order to solve the above problem, a servo method for a disk drive device according to claim 8 of the present invention is a servo method for a disk drive device that performs tracking servo, wherein a pickup is moved to a target track. When moving the pickup, the pickup is driven using access control, and when the pickup moves to a target track, the pickup is driven using sliding mode control to perform the tracking servo.
[0033]
According to the invention of claim 8, since the sliding mode control is used for the servo after the pickup is moved to the target track, a servo method of a disk drive device that can realize high stability by a disturbance suppression effect can be provided. .
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0035]
Note that the same or common portions are denoted by the same reference numerals in the drawings referred to in each embodiment, and description thereof will not be repeated.
[0036]
(1st Embodiment)
FIG. 1 is a block diagram illustrating a configuration example of the disk drive device according to the first embodiment of the present invention.
[0037]
The disk drive device shown in FIG. 1 includes a disk 1, a spindle motor 2, a pickup 3, a head amplifier 4, a linear controller 5A (corresponding to a normal control means), a sliding mode controller nonlinear controller 6A and a sliding mode controller. Vibration controller 8A (corresponding to vibration control means) including state feedback control unit 7A, vibration detector 9 (corresponding to vibration detection means), switching between linear controller 5A and vibration controller 8A A switching timing determiner 11A (corresponding to switching timing determining means) for determining timing, a changeover switch 12A (corresponding to selecting means) for switching the connection between the linear controller 5A and the vibration-time controller 8A, and the linear controller 5A or Pickup drive driver 1 that drives pickup 3 in response to a control signal from vibration controller 8A And a (corresponding to the pickup driving means). In FIG. 1, the head amplifier 4 shows a position detection signal 4S indicating a focus error signal or a tracking error signal, and various read signals 5S.
[0038]
Hereinafter, the operation of the disk drive device shown in FIG. 1 will be described.
[0039]
The disk 1 is rotated by a spindle motor 2. In the initial state, the changeover switch 12A is connected to the linear controller 5A. In a normal operation in which a normal servo that does not sense vibration is performed, the changeover switch 12A is connected to the linear controller 5A. At this time, the position detection signal 4S output from the pickup 3 through the head amplifier 4 enters the linear controller 5A, and based on the position detection signal 4S, the linear controller 5A receives a linear signal with respect to the pickup driving driver 13 during normal operation. The pickup driver 13 outputs a control signal (hereinafter referred to as a normal control signal) 5aS for performing control, and drives the pickup 3 according to the normal control signal 5aS.
[0040]
In this way, the disk drive device performs the focus servo and the tracking servo having a high follow-up property by driving the pickup 3 by the linear control based on the position detection signal 4S during the normal operation in which no vibration occurs. Is going.
[0041]
Further, during a normal operation in which no vibration occurs, while performing focus servo and tracking servo, the vibration detector 9 monitors at least one of a tracking error signal or a focus error signal as the position detection signal 4S, For example, it is determined whether or not the vibration state occurs by determining whether or not the amplitude of the signal exceeds a predetermined threshold. Further, the vibration detector 9 can easily determine the occurrence of the vibration based on the RF signal from the pickup.
[0042]
Next, when vibration occurs, the pickup 3 vibrates. At this time, it is determined that the vibration detector 9 monitoring the position detection signal 4S is in a vibration state, and for example, an active vibration detection signal 9S is given to the switching timing determiner 11A. Upon receiving the vibration detection signal 9S, the switching timing determiner 11A monitors the position detection signal 4S. Note that the switching timing determiner 11A may be configured to constantly monitor the position detection signal 4S.
[0043]
Further, the switching timing determiner 11A monitors the focus error signal and the tracking error signal as the position detection signal 4S, and in each of the focus servo and the tracking servo, when a switching line (surface) for switching to the sliding mode control is reached, Alternatively, if the error value of each error signal or the slope of each error signal becomes “0”, it is determined that it is time to switch to the vibration-time controller 8A.
[0044]
Then, the switching timing determiner 11A gives the changeover switch 12A a changeover signal 11aS instructing a changeover to the vibration-time controller 8A. The changeover switch 12A receives the changeover signal 11aS and switches to the vibration-time controller 8A. Therefore, the pickup drive driver 13 receives the vibration control signal 8aS from the vibration controller 8A and outputs a signal for driving the pickup 3.
[0045]
As described above, the vibration-time controller 8A includes the sliding mode controller nonlinear control unit 6A and the sliding mode controller state feedback control unit 7A. As described above, the sliding mode controller nonlinear control unit 6A performs control to forcibly restrict the phase state of the pickup 3 to a predetermined switching line (plane). Further, the sliding mode controller state feedback control unit 7A has a role of constantly grasping the phase state of the pickup 3 and adjusting the speed of convergence to the switching line (plane).
[0046]
As described above, in a normal operation that is not in a vibration state, linear control with good followability using the linear controller 5A is performed, and in a vibration state, a sliding mode control with a strong disturbance suppression effect is performed. As a result, it is possible to provide an optical disk device having high tracking performance and high disturbance suppression performance.
[0047]
In addition, since the switching to the sliding mode control is performed at a timing based on the error signal, the chattering effect that occurs when switching to the sliding mode control is reduced, and the switching can be performed smoothly.
[0048]
The switch timing determiner 11A outputs a switch signal 11aS, and the switch 12A receiving the switch signal 11aS switches the connection from the linear controller 5A to the vibration controller 8A. That is, as shown in FIG. 2, near the switching line σ to the sliding mode control (r1) or when the position error e or the differential value e of the position error, which is the respective phase state variable, is near “0” (r2 or r3). Since the mode is switched to the sliding mode control, the chattering effect generated at the time of switching to the sliding mode control is reduced, the switching can be performed smoothly, and stable sliding mode control is realized.
[0049]
When it is determined that the vibration has stopped and the vibration detector 9 is not in the vibration state, the changeover switch 12A is switched to the linear controller 5A side, and the pickup 3 is controlled by the normal operation control signal 5aS from the linear controller 5A. Performs servo with high tracking ability.
[0050]
(Second embodiment)
FIG. 4 is a block diagram illustrating a configuration example of the disk drive device according to the second embodiment.
[0051]
The disk drive device shown in FIG. 4 includes a disk 1, a spindle motor 2, a pickup 3, a head amplifier 4, a linear controller 5B, a sliding mode controller non-linear controller 6B, and a sliding mode controller state feedback controller 7B. The switching controller 8B (corresponding to the vibration controller), the access controller 20 (corresponding to the access controller), and the switching timing of the linear controller 5B, the access controller 20, and the retract controller 8B are determined. Switching timing determiner 11B (corresponding to switching timing determining means), changeover switch 12B (corresponding to selecting means) for switching the connection between linear controller 5B, access controller 20, and pull-in controller 8B, pickup drive driver 13 (Corresponding to pickup driving means).
[0052]
In FIG. 4, a tracking error signal 4S and various read signals 5S are shown from the head amplifier 4.
[0053]
In the disk drive shown in FIG. 4, a disk 1 is rotated by a spindle motor 2.
[0054]
In the initial state, the changeover switch 12B is connected to the linear controller 5B. The tracking error signal 4S output from the pickup 3 through the head amplifier 4 enters the linear controller 5B. Then, the linear controller 5B outputs a normal control signal 5bS to the pickup drive driver 13 based on the tracking error signal 4S. The pickup 3 performs normal tracking servo according to the normal control signal 5bS.
[0055]
Next, a case is considered in which access control for moving the pickup 3 to a target track is performed based on various read signals 5S and the like. At this time, the changeover switch 12B is connected to the access controller 20 side. The tracking error signal 4S output from the pickup 3 through the head amplifier 4 enters the access controller 20. Then, the access controller 20 outputs an access control signal 20S to the pickup drive driver 13 based on the tracking error signal 4S. The pickup drive driver 13 performs access control for moving the pickup 3 to a target track according to the access control signal 20S. During the access control, the switching timing determiner 11B monitors the tracking error signal 4S.
[0056]
Considering the same as in the first embodiment, the sliding mode control is performed near the switching line (plane) σ to the sliding mode control or when the position error e or the differential value e of the position error, which is the respective phase state variable, is near “0”. When the mode is switched to, the chattering action is reduced when switching from access control to sliding mode control, and stable sliding mode control is realized. Further, stable tracking servo with little chattering can be performed.
[0057]
When the pickup 3 is stabilized on the on-track, the changeover switch 12B is switched to the linear controller 5B, and the pickup 3 is driven according to the normal control signal 5bS from the linear controller 5B.
[0058]
【The invention's effect】
Since linear control is used for servo during normal operation where vibration does not occur, and sliding mode control is used for servo when vibration occurs, high follow-up by linear control and high disturbance due to the disturbance suppression effect of sliding mode control are used. A disk drive device capable of realizing stability can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a disk drive device according to a first embodiment of the present invention.
FIG. 2 is a diagram for explaining switching to sliding mode control.
FIG. 3 is a block diagram showing parameters.
FIG. 4 is a block diagram illustrating a configuration of a disk drive device according to a second embodiment of the present invention.
FIG. 5 is a diagram showing a focus error signal.
FIG. 6 is a diagram showing a tracking error signal.
FIG. 7 is a block diagram showing a configuration of a conventional disk drive device.
FIG. 8 is a diagram illustrating gain characteristics.
[Explanation of symbols]
1 Disc 2 Spindle motor 3 Pickup 4 Head amplifier 5A Linear controller (ordinary control means)
5B Linear controller 6A, 6B Sliding mode controller Nonlinear controller 7A, 7B Sliding mode controller State feedback controller 8A Vibration controller (vibration control means)
8B Pull-in controller (pull-in control means)
9 Vibration detector (vibration detection means)
11A, 11B switching timing determiner (switching timing determining means)
12A, 12B switch (selection means)
13 Pickup drive driver (pickup drive means)
20 access controller (access control means)
4S Position detection signal 5S Various reading signals 5aS, 5bS Normal control signal 8aS, 8bS Vibration control signal 9S Vibration detection signal 11aS, 11bS Switching signal 20S Access control signal

Claims (8)

In a disk drive device that performs at least one of focus servo and tracking servo based on an output signal from a pickup,
Pickup driving means for outputting a signal for driving the pickup,
A normal control unit that outputs a normal control signal for performing linear control on the pickup driving unit based on the output signal from the pickup;
Based on the output signal from the pickup, vibration control means for outputting a vibration control signal for performing a sliding mode control to the pickup driving means,
Vibration detection means for determining whether or not vibration has occurred in the disk drive device based on the output signal from the pickup, and outputting a vibration detection signal;
Selection means for selecting any of the normal control signal and the vibration control signal based on the vibration detection signal from the vibration detection means,
When the vibration detecting means determines that no vibration occurs in the disk drive device,
The selecting means selects the normal control signal,
The pickup driving means outputs a signal for driving the pickup in accordance with the normal control signal,
When the vibration detecting means determines that vibration has occurred in the disk drive device,
The selecting means is for selecting the vibration control signal,
The disk drive device, wherein the pickup driving means outputs a signal for driving the pickup in response to the vibration control signal. The disk drive device according to claim 1,
The disk drive device according to claim 1, wherein said vibration detection means determines whether or not vibration has occurred in said disk drive device based on an RF signal output from said pickup. The disk drive device according to claim 1,
The disk drive device according to claim 1, wherein the vibration detection means determines whether or not vibration has occurred in the disk drive device based on a focus error signal or a tracking error signal output from the pickup. The disk drive device according to claim 1,
Based on the focus error signal or the tracking error signal output from the pickup, when the value of the focus error signal or the tracking error signal becomes close to 0, or the focus error signal or the tracking error signal is determined in advance. Further comprising a switching timing determining means for outputting a switching timing signal for causing the selecting means to select the vibration control signal when near a switching line (surface) to the sliding mode control.
The disk drive device, wherein the selecting means selects the vibration control signal when receiving the switching timing signal. In a disk drive device that performs tracking servo based on a tracking error signal from a pickup,
Pickup driving means for outputting a signal for driving the pickup,
Access control means for outputting an access control signal for moving the pickup to a target track based on the tracking error signal from the pickup;
Based on the tracking error signal from the pickup, a pull-in control unit that outputs a pull-in control signal for performing a sliding mode control on the pickup driving unit,
Selection means for selecting one of the access control signal and the pull-in control signal based on an output signal from the pickup,
After the pickup has moved to a target track based on the access control signal from the access control means,
The selecting means selects the pull-in control signal,
The disk drive device, wherein the pickup driving means outputs a signal for driving the pickup in accordance with the pull-in control signal. The disk drive device according to claim 5,
Based on the tracking error signal, when the tracking error signal comes near a predetermined switching line (plane) to the sliding mode control, a switching timing signal for selecting the pull-in control signal to the selecting means is output. Further comprising a switching timing determining means for performing
The disk drive device, wherein the selecting means selects the pull-in control signal when receiving the switching timing signal. A servo method for a disk drive device that performs at least one of focus servo and tracking servo,
When performing a normal operation in which no vibration occurs in the disk drive device, drive the pickup using linear control, perform the focus servo or the tracking servo,
A servo method for a disk drive device, characterized in that when vibration occurs in the disk drive device, the pickup is driven using sliding mode control to perform the focus servo or the tracking servo. A servo method for a disk drive device that performs tracking servo,
When moving the pickup to the target track, drive the pickup using access control,
A servo method for a disk drive device, wherein when the pickup moves to a target track, the tracking servo is performed by driving the pickup using sliding mode control.

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