JP2007507822A - Disk drive device - Google Patents

Abstract

A method for controlling an optical disc drive device (1), the disc drive device comprising: scanning means (30) for scanning a recording track of the optical disc (2) and generating a read signal (SR); Based on the actuator means (50) for controlling the positioning of at least one read / write element (34) of the scanning means (30) with respect to the optical disc (2) and at least one signal component of the read signal (SR). ,
A control circuit (90) for receiving a read signal (SR) and generating at least one actuator control signal (SCR), the control circuit (90) having at least one variable control parameter; The method of having is disclosed. The method includes deriving at least two different types of signals (REn, MIRn) from the read signal (SR) and changing the setting of the at least one variable control parameter as a function of the at least two signals. And have. Another method is disclosed for distinguishing between two types of disturbances, a) disk defects and b) impact.

Description

  The present invention generally relates to an optical disc drive apparatus for writing information to or reading information from an optical storage disc.

  As is generally known, an optical storage disc has at least one track, either a continuous spiral of storage space or a plurality of dense circles, in which information is data It can be stored in the form of a pattern. An optical disc can be of a read-only type, in which information is recorded during manufacture and that information is only read by the user. Optical storage discs can also be of a writable type, in which information can be stored by a user. In order to write information to the storage space of an optical storage disk or to read information from an optical storage disk, an optical disk drive is on the one hand a rotating means for receiving and rotating an optical disk and on the other hand a light beam. Typically, it has optical means for generating a laser beam and for scanning a storage track using the laser beam. Since the optical disk technology is generally known as a method for storing information on the optical disk and a method for reading optical information light from the disk, detailed description of the technology is not necessary here.

  In order to rotate the optical disc, the optical disc drive typically has a motor that drives a hub that engages the central portion of the optical disc. In general, the motor is implemented as a spindle motor, and the hub driven by the motor can be provided directly on the spindle shaft of the motor.

  In order to optically scan a rotating disc, an optical disc drive includes a light beam generator (typically a laser diode), an objective lens for focusing the light beam on a focal point on the disc, and a disc. And a photodetector for receiving the reflected light reflected from and generating an output signal of the electrical detector. The photodetector has a plurality of detector segments, each segment providing an individual segment output signal.

  In operation, the light beam needs to remain focused on the disk. For this purpose, the objective lens is provided such that its axis is movable, and the optical disc drive has a focus actuator means for controlling the position of the objective lens axis. Further, the focus needs to be kept aligned with the track and needs to be positioned with respect to the new track. For this purpose, at least the objective lens is mounted such that it can move in the radial direction, and the optical disc drive has radial actuator means for controlling the radial position of the objective lens.

  In many disk drives, the objective lens is arranged to be tiltable, and such an optical disk drive has tilt actuator means for controlling the tilt angle of the objective lens.

  In order to control these actuator means, the optical disk drive has a controller that receives the output signal from the photodetector. From this signal (hereinafter referred to as the read signal), the controller generates one or more error signals such as, for example, a focus error signal, a radial error signal, etc., and based on those error signals, the controller Generates an actuator control signal for controlling the actuator means to reduce or eliminate position errors.

  In the process of generating the actuator control signal, the controller exhibits certain control characteristics. Such a control characteristic is a feature of the controller that is described as a way in which the controller behaves in response to detection of a position error.

Position errors can in particular be caused by different types of disturbances. Their most important disturbance class is
1) Disk defect 2) Impact from outside and periodic vibration.

  The first category has defects in the disc such as black spots, contamination such as fingerprints, and damage such as scratches. The second category has shocks caused by those that impact the disk drive, but shocks and vibrations are primarily expected in portable disk drives and automotive applications. Whatever the difference in cause, an important distinction between defects on one disk and shock and vibration on the other is the frequency range of signal disturbances. Signal disturbances caused by disk defects typically have high frequencies, while shocks and vibrations typically have low frequencies.

  The problem with this is that properly handling the first category of disturbances requires different control characteristics than properly handling the second category of disturbances. Traditionally, disk drive controllers have fixed control characteristics, which are specially adapted to properly handle the first category of disturbances (in which case error control is in the second category). Or the control characteristics are compromised (in which case error control is not optimal for the first category of disturbances and the second category of disturbances) Either. As long as the controller applies linear control techniques, there is always a compromise between low frequency disturbance rejection and high frequency sensitivity to noise measurements.

  In such state of the art, it has already been proposed to change the gain of the controller depending on the type of disturbance experienced. For example, reference can be made to US Pat. No. 4,722,079.

  It is necessary to determine which disturbance classes exist so that a controller with variable gain can be implemented. In said patent document, U.S. Pat. No. 4,722,079, the optical read signal is processed to determine the class of disturbance, but the system describes a system that requires a three beam optical system. Has been.

  US Pat. No. 5,867,461 also describes a system in which the optical read signal determines the class of disturbance. In this known system, the envelope of the high frequency signal content is determined. One disadvantage of this method is that it relies on data written to the disk. It is not applicable for blank discs. Other disadvantages are that the method is specifically for detecting upper and lower peaks, for filtering to detect upper and lower envelopes, and for analyzing their envelopes. In addition, in order to store the signal in the memory, a complicated circuit configuration is required.

  Common problems are associated with adapting their control characteristics in disk drives that can handle disk defects and mechanical shock. Changing the control characteristics so that one type of disturbance is better handled can have a significant impact on the ability of the controller to handle other types of disturbances.

Further, in the present invention, it has been found that a single detection signal is not always a reliable source of information for distinguishing between mechanical shock and disk defects. In other words, certain events can be generated in the case of a mechanical shock as well as in the case of a disk defect, so that certain events are error-prone to be determined as a disk defect or as a mechanical shock. It becomes.
U.S. Pat. No. 4,722,079 US Pat. No. 5,867,461

  It is a general object of the present invention to provide a method for reliably determining whether an event corresponds to the presence of a mechanical shock or to the presence of a disk defect.

  Furthermore, it is an object of the present invention to provide a method for determining a class of disturbance that can be implemented relatively easily.

  Furthermore, an object of the present invention is to provide a method for changing the control characteristics of the controller based on the result of the above determination.

  In accordance with a first important feature of the present invention, a method for distinguishing different types of disturbances in a disk drive device is based on receiving and processing at least two types of signals, each resulting from a detector signal. ing. The first type of signal is a signal based on the integration of the output signals of two or more individual segments. A preferred first type of signal is an integration, which is generated by generating a weighted integration of the output signals of all the individual segments of the detector segment. Such kind of signal 1 is an indicator of the reflectivity of the disc (ie "disc quality") and is mainly influenced by disc defects.

  The second type of signal is a signal based on the integration of the output signals of two or more individual segments, at least one of which is a signal multiplied by -1. Such kind of signal 2 represents only the presence of a position error.

  The first type of signal can provide a specific response indicative of a disk defect or impact. Similarly, the second type of signal can provide a specific response in the event of a disk defect or impact. In accordance with a second important feature of the present invention, a disk defect or impact is determined only if both the first and second type signals are coincident with each other, and therefore the possibility of error determination. Is reduced.

  The distinction between impacts in the longitudinal direction (ie parallel to the disc rotation axis) and impacts in the transverse direction ie perpendicular to the disc rotation axis is the focus error signal or rotation error signal. Note that this is done by considering each one.

  These and other aspects, features and advantages of the present invention are described in detail below with reference to the drawings. In the drawings, like reference numbers indicate similar or similar components.

  FIG. 1A schematically shows an optical disc drive 1 that is typically suitable for storing information from or reading information from a DVD or CD. In order to rotate the disk 2, the disk drive device 1 has a motor 4 fixed to a frame (not shown for simplicity) that defines a rotating shaft 5.

  More specifically, in the exemplary configuration shown in FIG. 1A, the optical system 30 is a light beam generating means 31 configured to generate a light beam 32, typically a laser diode. Have such a laser. In the following, the different parts of the light beam 32 after the optical path 39 are indicated by the letters a, b, c etc. attached to the reference number 32.

  The light beam 32 passes through a beam splitter 33, a collimator lens 37, and an objective lens 34 in order to reach the disk 2 (beam 32b). The objective lens 34 is designed to focus the light beam 32b on the focal point F in the recording layer (not shown for simplicity) of the disc. The light beam 32b is reflected from the disk 2 (reflected light beam 32c) and passes through the objective lens 34, the collimator lens 37 and the beam splitter 33 so as to reach the photodetector 35 (beam 32d). In the illustrated case, for example, an optical element 38 such as a prism is inserted between the beam splitter 33 and the photodetector 35.

  The disk drive device 1 further comprises an actuator system 50, which has a radial actuator 51 for moving the objective lens 34 immediately with respect to the disk 2. Since radial actuators are known per se, the present invention does not describe the design and function of such radial actuators, and need not be described in detail with respect to the design and function of radial actuators.

  In order to achieve and maintain the current focusing accurately at the desired disk 2 position, the objective lens 34 is provided to be axially movable, while in addition, the actuator system 50 also provides an objective with respect to the disk 2. A focus actuator 52 is provided for moving the lens 34 in the axial direction. Since focus actuators are known per se, the present invention does not describe the design and function of such focus actuators and need not be described in detail with respect to focus actuator design and function.

  To achieve and maintain an accurate tilt position of the objective lens 34, the objective lens 34 can be provided in the center. In such a case, as shown, the actuator system 50 also has a tilt actuator 53 provided for pivoting the objective lens 34 with respect to the disk 2. Since tilt actuators are known per se, the present invention does not describe the design and function of such tilt actuators and need not be described in detail with respect to the design and function of tilt actuators.

  It is further noted that the means for supporting the objective lens with respect to the apparatus frame, the means for moving the objective lens in the axial and radial directions, and the means for pivoting the objective lens are themselves well known. Since the design and operation of such support means and movement means are not the subject of the present invention, their design and operation need not be described in detail here.

  It is further noted that the radial actuator 51, the focus actuator 52 and the tilt actuator 53 can be implemented as one integrated actuator.

The disk drive device 1 has a first output 92 coupled to the control input of the motor 4 and has a second output 93 coupled to the control input of the radial actuator 51 and coupled to the control input of the focus actuator 52. And a control circuit 90 having a fourth output 95 coupled to the control input of the tilt actuator 53. Control circuit 90 generates the control signal S _CM was generated in the first output 92, a second output 93 a control signal S _CR for controlling the radial actuator 51 for controlling the motor 4, the focus actuator 52 _Is designed to generate a control signal _SCF at the third output 94 and control signal SCT to control the tilt actuator 53 at the fourth output 95.

The control circuit 90 further has a read signal input 91 for receiving a read signal S _R from the photodetector 35. In the case shown in FIG. 1B, the photodetector 35 provides an individual detector signal A, B, C, D, S1, S2 representing the amount of light incident on each of the six detector segments. It has six detector segments 35a, 35b, 35c, 35d, 35e and 35f that can be. Four detector segments 35a, 35b, 35c, 35d, shown as central aperture detector segments, are also provided in a four-quadrant configuration. The center line 26 separating the first segment 35a and the fourth segment 35d from the second segment 35b and the third segment 35c has a direction that coincides with the track direction. The two detector segments 35e, 35f are also shown as satellite detector segments, which can be subdivided into sub-segments, on the opposite side of the center line 36, in the center detector quadrant. In addition, it is provided symmetrically. Since such a six-segment detector is well known per se, its design and function need not be described in further detail here.

  It should be noted that various designs for photodetectors are also possible. For example, satellite segments are well known per se and will not be described in detail.

  FIG. 1B also shows that the read signal input 91 of the control circuit 90 actually has multiple inputs for receiving all of the individual detector signals. Therefore, in the case of the illustrated six quadrant detector, the read signal input 91 of the control circuit 90 actually receives the individual detector signals A, B, C, D, S1, S2 respectively. There are six inputs 91a, 91b, 91c, 91d, 91e, 91f. As will be clearly understood by those skilled in the art, the control circuit 90 provides the individual detector signals A, B, C, D, S1 to obtain the data signal and one or more error signals. , Designed to handle S2. Hereinafter, the radial error signal indicated as the inter-unit RE represents the radial distance between the track and the focal point F. Hereinafter, the focus error signal, simply denoted as FE, represents the axial distance between the storage layer and the focus F. It should be noted that various equations for error signal calculation can be used depending on the design of the photodetector. In general, each such error signal is an indicator for the asymmetry of a certain central light spot at the detector 35 and is therefore affected by the movement of the light scanning spot with respect to the disk.

The specific signal obtained by processing the individual detector signals is given by the following equation: MIRn = A + B + C + D + W (S1 + S2) (1)
Is the mirror signal MIRn obtained by weighted addition of all the individual detector signals A, B, C, D, S1, S2, where W is a weighting factor, typically about 15 It is an order. This signal is an indicator of the reflectivity of the disk.

In contrast, a normal error signal, such as REn, is at least one (but not all) of the signals that are inverted (ie, multiplied by -1), as is well known to those skilled in the art. It is obtained by appropriately adding a part (or all) of the individual detector signals A, B, C, D, S1, S2. As an example, the radial error signal REn is expressed by the following formula: REn = ((A + D) − (B + C) −W (S1−S2)) / (A + B + C + D + S1 + S2) (2)
Where W is a weighting factor.

  The control circuit 90 is designed to generate a control signal as a function of the error signal, as will be apparent to those skilled in the art, to reduce the corresponding error. In this case, the control circuit 90 has a variable control characteristic corresponding to the type of error. In the case of an error due to a disk defect, the control characteristics of the control circuit 90 are adapted according to a first strategy for properly handling the disk defect. In the case of an error due to an external impact, the control characteristics of the control circuit 90 are adapted according to a second strategy for appropriately handling the external impact, the second strategy being different from the first strategy.

  The exact nature of those control characteristics to be adapted is a matter of design. For example, the gain in the control circuit can be adapted. The selection of which parameters of the control circuit are to be adapted is not the subject of the present invention. Furthermore, since control circuits with variable gain are well known per se, it is not necessary to describe here the details of how the circuit parameters can actually be changed to adapt the control characteristics.

  Therefore, generally speaking, the control characteristic of the control circuit 90 has a plurality of variable control parameters. At least one setting of these variable control parameters is varied as a function of at least two detection signals, ie, at least two signals of the first and second types described above, wherein the first strategy is a disc The second strategy is implemented with high reliability in the case of defects, and the second strategy is implemented with high reliability in the case of external impacts or vibrations.

  Hereinafter, such a feature of the present invention will be described in detail by taking a control circuit having a variable gain as an example.

FIG. 2 is a block diagram schematically illustrating a part of the exemplary control circuit 90. For purposes of explanation, this portion of the control circuit 90 may be related to the control of the radial actuator 51. The control circuit 90 is assumed to have a PID controller 60 having an input 61 and an output 69. The radial error signal is received at input 61 and provided to a first common amplifier 71 having a variable gain k1. The PID controller 60 has three parallel branches: a P branch 62, an I branch 63, and a D branch 64, each of which receives an amplified input signal, and each of them has a variable gain. Each of the amplifiers 72, 73, and 74 has k2, k3, and k4. P branch 62 has a P processor 65 supplies the P signal _{S P} to a summing point 68. I branch 63 has an I processor 66 supplies the I signal _{S I} to the summing point 68. The D branch 64 includes a D processor 67 that supplies a D signal _SD to the addition point 68. The summing point output signal S + is provided to a second common amplifier 75 having a variable gain k5.

In at least one of the gains k _i (where i is a number in the range of 1 to 5), preferably all of the gains vary in response to at least two types of signals, each of which is a photodetector. obtained from the signal _{S R.} Therefore, each gain k _i is represented as a function f _i (x1, x2) of the two signals x1 and x2, and the signals x1 and x2 represent the two types of signals, respectively. In the preferred embodiment, the mirror signal MIRn is used as the first type of signal x1, and the normalized radial error signal REn is used as the second type of signal x2.

  The mirror signal MIRn is an index for the reflectivity of the disk. Typically, this signal is a substantially constant value, hereinafter referred to as M, which is substantially independent of shock or vibration, but decreases quickly in the case of a disk defect. . Hence, MIRn allows a distinction between disk defects and impact. For example, a disk defect can easily be determined to exist when MIRn <α · M, where α is a predetermined threshold coefficient, for example, α = 0.9. Alternatively, instead of the mirror signal MIRn, another signal based on the addition of two or more individual segment output signals can be used as the first type of signal. An example of such an alternative signal that is suitable for use as the first type of signal in connection with the present invention is CA = A + B + C + D.

  The normalized radial error signal REn is an indicator of the movement of the light spot in the radial direction. Alternatively, instead of the normalized radial error signal REn, two or more individual segment output signals, ie at least one (but not all) of those signals multiplied by −1 Can be used as the second type of signal. Examples of such alternative signals that are suitable for use as the second type of signal in connection with the present invention are S1-S2, AB, and FEn.

  As an example, FIG. 3 shows a possible first function f1 for changing the first gain k1. The functions for changing the other gains k2 to k5 can be the same as k1, but the individual functions for changing the other gains k2 to k5 can also be different from each other. The overall shape of the function is at least similar.

  FIG. 3 is a graph having a curve 80 showing the gain k1 (vertical axis) as a function of the radius error REn (horizontal axis) for different values of MIRn. It should be clear that it is possible to show k1 as a function of MIRn (lateral axis) for different values of REn, or to show k1 as a three-dimensional graph.

In the illustrated embodiment, the first gain k1 has a nominal value k1,0. Since the radial error is relatively small, ie smaller than the threshold _RT , the first gain k1 is kept constant at its nominal value k1, 0 (lateral stem 81 of the curve 80). If the radial error is greater than the threshold value RT, the first gain k1 increases (first branch 81 of the curve 80) or decreases (second branch 82 of the curve 80) depending on the second type of input signal MIRn. . When the MIRn has a value indicating a disk defect, the first gain k1 decreases. Otherwise, if MIRn has a value indicating shock or vibration, the first gain k1 increases. The amount of decrease or increase depends on the magnitude of REn. Therefore, the value of the first gain k1 is selected in two signal dependencies.

In principle, the present invention has already been implemented when only one value of the gain depends on the at least two signals. Preferably, however, two or more of the gains change based on at least two signals, and more preferably all of the gains change. Each gain can be associated with a corresponding threshold, but preferably the threshold _RT is the same for all gains. Further, each of the gains can be set according to an individual function of two (or more) signals, but preferably such a function (curve 80) is the same for all gains.

  FIG. 4 is a graph showing the effect of the present invention related to the gain k1. The left part of FIG. 4 shows, for example, the case of (periodic) vibration at 40 Hz, while the right part of FIG. 4 shows the case of a disk defect (black dot).

  Each of the curves 101 and 102 shown by the dashed line shows the behavior of the radial error signal REn when all the gains are kept constant at their nominal values, so the control circuit 90 is linear. Execute control. Curve 101 shows the sinusoidal behavior of REn in the case of (periodic) vibration. In the case of a black spot, curve 102 shows a large peak corresponding to the incidence of the light spot and leaving a black spot.

The solid line 103 shows the behavior of the radial error signal REn when the present invention is applied in the case of (periodic) vibration. In the first time interval before time t1, the radial error signal REn is less than the threshold _RT , so k1 is at its nominal value k1,0 (this is the stem of curve 80 in FIG. 3). 83). At time t1, the radial error signal REn rises above the threshold _RT , while MIRn has a nominal value M indicated by curve 111. Corresponding to the branch 81 of the curve 80 in FIG. 3, in this case it increases from the nominal value k1, 0 so as to reach the maximum value k1 _MAX indicated by the curve 121. Although REn still rises above the threshold _RT , it is true that the maximum value reached by REn is small compared to the case of linear control (curve 101).

When REn decreases, gain k1 also decreases, and at time t2, gain k1 reaches the nominal value k1, 0 again when REn falls below threshold _RT .

The process itself, when the absolute value of REn rises above approximately the threshold R _T, is repeated.

The solid line 104 shows the behavior of the radial error signal REn when the present invention is applied in the case of a disk defect. In the first time interval before time t3, the radial error signal REn is less than the threshold value RT, so the gain k1 is at the nominal value k1,0 (this is in the stem 83 of the curve 80 in FIG. 3). Yes) At time t3, radial error signal REn rises above threshold _RT , while MIRn falls below nominal switching threshold αM indicated by curve 112. Corresponding to the branch 82 of the curve 80 in FIG. 3, in this case, it decreases from the nominal value k 1, 0 to reach the minimum value k 1 _MIN indicated by the curve 122. Although REn still rises above the threshold RT, it is true that the maximum value reached by REn is smaller than in the case of linear control (curve 102).

When REn decreases, gain k1 increases, at time t4, when REn falls below the threshold value _{R T,} gain k1 is reached again nominal value K1,0. The light spot now leaves a black spot and the mirror signal MIRn recovers the nominal value M.

  Although the present invention is not limited to the above-described exemplary embodiments, it should be understood that various changes and modifications may be made within the scope of the present invention as set forth in the appended claims. It is clear to the contractor.

  In the above, the present invention has been described in relation to embodiments in which one or more gains are set according to two optical signals. For example, it is possible to adapt other parameters of the actuator control, such as the cut-off frequency of the high-pass filter or low-pass filter, or the center frequency of the band-pass filter or band-reject filter. It will be apparent to those skilled in the art that any control parameter that is optimally set differently in the case of impact and in the case of a disk defect can be adapted in the above manner. Furthermore, any such control parameter can be set based on three or more signals. In the above exemplary embodiment, for example, a focus error signal can be used as the third signal representing the impact in the Z direction.

  In the above, the present invention has been described in relation to an embodiment using a six-part photodetector. It will be apparent to those skilled in the art that detectors with various designs are feasible, in which case the equations for the error signal can be different.

  In the above, the present invention has been described in relation to a block diagram showing functional blocks of an apparatus according to the present invention. One or more of these functional blocks can be implemented in hardware, in which the functions of such functional blocks are performed by individual hardware components, and One or more of the functional blocks are implemented in software, and thus the functionality of such functional blocks is, for example, one or more of a programmable device such as a microprocessor, a microcontroller or a computer program. It needs to be understood that it is executed by the program line.

It is a schematic diagram which shows the related component of an optical disk drive device. It is a schematic diagram which shows embodiment of a photodetector in detail. It is a block diagram which shows an actuator control circuit typically. It is a graph which shows typically the function for changing the parameter of an actuator control circuit. It is a timing diagram of a signal showing the operation of the present invention.

Claims (26)

A method for distinguishing various types of disturbances in an optical disk drive device, the disk drive device:
Scanning means for scanning a recording track of the optical disc and for generating a read signal;
A method having
Extracting at least two different types of signals from the pre-read signal; and if one of the signals is within a first value range while the other of the signals is within a second value range, If it is determined that the disturbance corresponds to an impact or vibration, and the one of the signals is in the first value range while the other of the signals is in a third value range, the disturbance is a disc Determining that it corresponds to a defect of
A method characterized by comprising:   2. The method of claim 1, wherein the one of the signals is a signal that is an indicator for movement of a light spot.   2. The method of claim 1, wherein the one of the signals is a signal that is an indicator of some asymmetry of a central light spot at the detector.   The method of claim 1, wherein the one of the signals is a radial error signal.   The method of claim 1, wherein the one of the signals is a focus error signal.   2. The method of claim 1, wherein the other of the signals is a signal that is an indicator of the reflectivity of the disk. The method of claim 1, wherein:
Said scanning means comprises a plurality of detector segments each for receiving a reflected light beam and for generating individual detector signals; and said one of said signals is two or more individual segment output signals A signal based on the addition of at least one of their individual segment output signals, but not all, multiplied by −1;
A method characterized by that. The method of claim 1, wherein:
Said scanning means comprises a plurality of detector segments each for receiving a reflected light beam and for generating individual detector signals; and said other of said signals is two or more individual segment output signals A signal based on the addition of
A method characterized by that.   9. The method of claim 8, wherein the other of the signals is a normalized mirror signal that is the sum of all individual detector signals from all detector segments.   9. The method of claim 8, wherein the other of the signals is a central aperture signal that is the sum of all individual detector signals from four central aperture detector segments provided in a four quadrant configuration. A method characterized in that A method for controlling an optical disc drive apparatus, the disc drive apparatus:
Scanning means for scanning a recording track of the optical disc and for generating a read signal;
Actuator means for controlling the positioning of at least one read / write element of the scanning means with respect to the disk; and at least one actuator control signal for receiving the read signal based on at least one signal component of the read signal A control circuit for generating a control circuit, the control circuit having at least one variable control parameter;
Having a method,
Distinguishing different types of disturbances using the method according to claim 1; and changing the setting of said at least one variable control parameter according to a first strategy in the event of a disk defect and shock or vibration Changing the setting of the at least one variable control parameter according to a second strategy in the case of
A method characterized by comprising: A method for controlling an optical disc drive apparatus, the disc drive apparatus:
Scanning means for scanning a recording track of the optical disc and for generating a read signal;
Actuator means for controlling the positioning of at least one read / write element of the scanning means with respect to the disk; and at least one actuator control signal for receiving the read signal based on at least one signal component of the read signal A control circuit for generating a control circuit, the control circuit having at least one variable control parameter;
A method having
Deriving at least two different types of signals from the read signal; and changing the setting of the at least one variable control parameter as a function of the at least two signals;
A method characterized by comprising:   The method of claim 12, wherein the at least one variable control parameter is a gain of a signal processing component of the control circuit.   13. The method of claim 12, wherein the at least two signals are signals that are indicators of the reflectivity of the disk. The method of claim 12, wherein:
Said scanning means comprises a photodetector having a respective plurality of detector segments for receiving the reflected light beam and for generating individual detector signals;
The first type of the at least two signals is a signal based on the addition of two or more individual segment output signals;
A method characterized by that.   16. The method of claim 15, wherein the first type of signal is a normalized mirror signal that is the sum of all individual detector signals from all detector segments.   16. The method of claim 15, wherein said first type of signal is a summation of all individual detector signals from four central aperture detector segments provided in a four quadrant configuration state. A method characterized by being an aperture signal.   13. The method according to claim 12, wherein the second type of the at least two signals is a signal that is an indicator of light spot movement.   13. The method of claim 12, wherein the second type of the at least two signals is a signal that is an indicator for some asymmetry of the central light spot of the photodetector. A method characterized by. The method of claim 12, wherein:
The scanning means has a plurality of detector segments each for receiving a reflected light beam and for generating individual detector signals; and the second type of the at least two signals is two or more A signal based on the addition of the above individual segment output signals, at least one of which is multiplied by −1;
A method characterized by that.   The method of claim 18, wherein the second type of the at least two signals is a radial error signal.   19. The method of claim 18, wherein the second type of the at least two signals is a focus error signal. The method of claim 12, wherein:
The at least one variable control parameter has a nominal value as long as the second type of signal is less than a predetermined threshold;
The at least one variable control parameter satisfies a first condition in which the second type of signal is greater than the predetermined threshold while the first type of signal indicates a disturbance caused by mechanical shock or vibration. If so, the at least one variable control parameter is such that the second type of signal is greater than the predetermined threshold while the first type of signal is from a disc defect. Change in a second direction different from the first direction if a second condition indicative of the disturbance introduced is satisfied;
A method characterized by that. The method of claim 12, wherein:
The at least one variable control parameter has a nominal value as long as the second type of signal is less than a predetermined threshold;
The at least one variable control parameter satisfies a first condition in which the second type of signal is greater than the predetermined threshold, while the first type of signal indicates a standard reflectivity of the disk. And wherein the at least one variable control parameter is such that the second type of signal is greater than the predetermined threshold while the first type of signal is reduced. When the second condition indicating the reflectivity of the second condition is satisfied, the second direction is different from the first direction;
A method characterized by that. A disk drive device:
Scanning means for scanning a recording track of the optical disc and for generating a read signal;
Actuator means for controlling the positioning of at least one read / write element of the scanning means with respect to the disk; and at least one actuator control signal for receiving the read signal based on at least one signal component of the read signal A control circuit for generating a control circuit, the control circuit having at least one variable control parameter;
A device having
The control circuit is adapted to perform the method of claim 1;
A disk drive device characterized by that. A disk drive device:
Scanning means for scanning a recording track of the optical disc and for generating a read signal;
Actuator means for controlling the positioning of at least one read / write element of the scanning means with respect to the disk; and at least one actuator control signal for receiving the read signal based on at least one signal component of the read signal A control circuit for generating a control circuit, the control circuit having at least one variable control parameter;
A device having
The control circuit is adapted to perform the method of claim 12;
A disk drive device characterized by that.

Images