JP2000090461A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute eccentricity correction with simple constitution and to reduce a cost by driving a revolving motor in accordance with the eccentricity rate obtained from a tracking error signal and an index signal and moving a positioner by means of a gear train to a direction crossing a track. SOLUTION: The positioner 5 has a rack 6, receives the driving force of the revolving motor 8 via a pinion 7 and moves in the radial direction of an optical disk 1. A tracking error signal detector 12 mounted on the positioner 5 outputs the tracking error signal 13. An eccentricity information memory section 15 determines the max. eccentricity rate and phase of the mounted optical disk 1 from an index signal 4 and the tracking error signal 13 in the state of turning off tracking servo before starting the writing and reading of the information to the optical disk 1 and stores the same. Next, the delay and gain of the drive system of the positioner 5 are corrected in an eccentricity correction section 16 and thereafter the revolving motor 8 is driven via a drive circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus, and more particularly, to an optical disk apparatus having a structure in which a positioner on which an actuator is mounted is moved by a rotary motor via a gear and the eccentricity of the optical disk is corrected by the positioner.

[0002]

2. Description of the Related Art In an optical disk device, after an optical disk is fixed to a turntable connected to a spindle motor, the optical disk is rotated at a predetermined rotation speed by the spindle motor. Due to the processing accuracy of the center hole of the optical disc used for positioning when fixing the optical disc to the turntable, the fitting part of the turntable, mounting accuracy, and the position accuracy of the track itself, the optical disc is rotated. The truck rotates eccentrically. Therefore, it is necessary to cause the light beam to follow the eccentrically rotating track.

There are two methods for causing the light beam to follow the eccentricity: a method of following only with an actuator equipped with an objective lens, and a method of following with both an actuator and a positioner equipped with this actuator.

The former method is used in an optical disk device for a compact disk (hereinafter referred to as a CD device) requiring a relatively wide track pitch and a low cost, and the latter method is a magneto-optical disk having a narrow track pitch. It is used in large-capacity optical disk devices such as the above.

[0005]

An optical disk has a large storage capacity and is used as an external storage medium of various information processing apparatuses.
It has become a must. In order to spread this optical disk, a technique is required that can cope with the track position fluctuation due to the eccentricity inherently associated with the optical disk device and that can reduce the cost and increase the capacity.

[0006] However, in the above-mentioned conventional CD apparatus, a DC motor is used as a drive source of the positioner, and the positioner is moved via a gear train. Since the eccentricity is tracked only by the actuator,
The following problems arise. Since the eccentricity is followed only by the actuator, the servo residual, that is, the positional deviation between the target track and the light beam increases.・ Because the amount of movement of the actuator in the track direction (the direction traversing the track) increases, the inclination of the optical axis of the objective lens mounted on the actuator increases,
Further, the optical axis of the light beam shifts from the neutral position, and the light beam cannot accurately irradiate a predetermined track.

[0007] Due to the above problems, the data recording / reproducing characteristics are reduced, for example, the C / N ratio is reduced.

On the other hand, in an optical disk apparatus using an optical disk having a narrow track pitch, such as a magneto-optical disk, most of the fluctuation of the track position due to eccentricity is tracked by the positioner. ing. Therefore, there is no problem as in the above-described CD device, but since the positioner is moved by a voice coil motor using an expensive large-volume permanent magnet, the cost of the optical disk device is increased. I have.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a configuration in which a positioner is moved by a rotary motor via a gear train, and eccentricity can be corrected by moving the positioner.

[0010]

According to a first aspect of the present invention, there is provided a configuration in which a positioner follows a track position change caused by eccentricity. In an optical disk apparatus on which an optical disk can be mounted, a light beam irradiated on the optical disk is A rotary motor that drives a positioner having an actuator that can move in a direction traversing the track via a gear train so that the actuator can move in a direction traversing the track; and a positional relationship between the light beam and the track. An eccentricity information storage unit for storing an eccentricity amount and phase information of the optical disc obtained from an output signal of a track deviation detector for detecting a corresponding signal and an index signal generated for each rotation of the optical disc, When the light beam tracks the track, the eccentricity amount and the phase information of the eccentricity information storage unit are The optical disk apparatus characterized by driving the rotary motor based on the the gist.

The actuator is preferably a two-dimensional actuator which can move in a direction crossing the track, that is, in a tracking direction, and can move a convergence position of the light beam in a direction perpendicular to the optical disk surface, ie, in a focusing direction. .

The gear train preferably has a one-stage gear train in which gears are provided for a positioner and a rotary motor, respectively.
A multi-stage gear train may be used.

The rotary motor is preferably a DC motor, but may be an AC motor, a stepping motor or the like.

With such a configuration, the positioner is controlled by the output of the eccentricity information storage section based only on the index signal and the output of the track deviation detector, so that the eccentricity due to the rotation of the optical disk can be corrected. Is reduced in the track direction.

According to a second aspect of the present invention, in addition to the first aspect, the present invention relates to removing the offset of the distance between the actuator and the positioner caused by disturbance such as vibration by moving the positioner. A signal detection unit that detects a signal corresponding to the distance between the signal detection unit and a correction signal generation unit that configures an eccentricity correction signal having a signal component lower than a predetermined frequency from an output signal of the signal detection unit; The gist of the present invention is an optical disc device characterized in that an output signal of a signal generation unit is added to a drive signal of the rotation motor to drive the rotation motor.

[0016] With this configuration, the movement of the actuator lower than the predetermined frequency is performed by driving the positioner by the output signal of the correction signal generation unit, so that the amount of movement of the actuator is reduced.

According to a third aspect of the present invention, in the signal detecting section according to the second aspect of the present invention, the signal detecting section detects a signal corresponding to the distance based on a current flowing through a tracking coil of the actuator. The gist of the invention is an optical disk device according to claim 2.

Since the amount of movement of the light beam in the track direction is determined by the current flowing through the tracking coil of the actuator, the distance between the actuator and the positioner can be equivalently detected by detecting this current.

According to a fourth aspect of the present invention, there is provided an optical disk device in which a positioner is of a swing type which is rotatable around one axis.

According to the fifth aspect of the invention, the eccentricity is corrected by the positioner in a feedback control system in which the eccentricity is a target value and the movement amount of the positioner is a control amount. Here, the bandpass amplifying unit and the phase compensating unit may be configured by a circuit, and are preferably configured by a DSP. Also,
The processing may be performed by a microprocessor. The processing order of the band-pass amplification and the phase compensation may be performed first.

According to a sixth aspect of the present invention, the band-pass amplifier of the fifth aspect amplifies only a predetermined band including the rotation frequency of the optical disk, and performs eccentricity correction by the positioner without widening the servo band. The control error is reduced gradually.

According to the present invention, the output signal of the position detecting sensor for detecting the positional relationship between the actuator and the positioner is amplified by the band-pass amplifier and phase-compensated by the phase compensator, thereby controlling the eccentricity correction by the positioner. Is gradually reduced. Here, the bandpass amplifying unit and the phase compensating unit may be configured by a circuit, and are preferably configured by a DSP. Further, the processing may be performed by a microprocessor. The processing order of the band-pass amplification and the phase compensation may be performed first.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment is characterized in that a positioner is driven by a rotary motor, and a position change of a track based on eccentricity is corrected by movement of the positioner. In the first embodiment, the case where the tracks are arranged on concentric circles and the rotation period of the optical disk is constant will be described as an example. It is also applicable to the case.

The eccentricity correction at the time of tracking servo, which is the main point of the present invention, will be described in detail with reference to FIGS. Control of seeks, writing of information on optical discs,
Since reading and focusing control are performed by a known method, the description is omitted.

FIG. 1 is a diagram showing the main configuration of the first embodiment, FIG. 2 is a diagram showing the configuration around the actuator, FIG. 3 is a diagram for explaining the amount of eccentricity, and FIG. FIG. 5 is a diagram illustrating an example of a tracking error signal and an index signal in the case where the error occurs, FIG. 5 is a diagram illustrating a specific example of an eccentricity information storage unit used in the first embodiment, and FIG. FIG. 3 is a diagram showing an embodiment of a linear positioner used for the present invention.

FIG. 1A shows a main part of the optical disk apparatus of the present invention. The optical disk 1 has a spindle motor 2
Is mounted on the turntable 3 provided in the
It is rotated at a predetermined rotation speed.

The spindle motor 2 has a configuration for transmitting an index signal 4 for each rotation, and the present embodiment employs a configuration in which one index signal 4 is generated for each rotation. This spindle motor 2
For example, since control is performed by a known technique so as to rotate at a constant rotational speed of 3,600 rpm, the control of the spindle motor 2 is omitted in this embodiment. Further, in the present embodiment, the optical disc 1 is rotated at a constant rotation speed, but the present invention can be applied to a method of rotating at a constant peripheral speed.

A rack 6 is fixed to the positioner 5, and a pinion 7 meshing with the rack 6 is fixed to a rotating shaft of a rotary motor 8. With this configuration, when the rotation motor 8 rotates in the normal and reverse directions, the positioner 5 can move in the radial direction of the optical disc 1 as shown in FIG. The mechanism for moving the positioner 5 will be described later.

Further, the positioner 5 is equipped with an optical unit 60, an actuator 9, and a tracking error signal detector 12. The actuator 9 collects the laser light from the optical unit 60 and
Objective lens 11 for irradiating the objective lens 1 and the objective lens 1
1 is mounted with a tracking coil 10 for moving 1 in the track direction. Here, the actuator 9 is capable of moving the convergence position of the laser beam in a direction perpendicular to the optical disk surface, that is, in the focus direction. Is detected, and the focus coil of the actuator 9 can be driven through a filter for phase compensation or the like, but a focusing coil, a focus servo, and the like are not shown.

A tracking error signal 13, which is an output signal of the tracking error signal detector 12, indicates a deviation between the irradiation position of the laser beam and the track position. The current flowing through the tracking coil 10 is controlled so that the error signal 13 falls within the allowable range.

Next, the positioner 5 which is the main point of the present invention will be described.
A configuration for correcting eccentricity will be described.

In the eccentricity information storage unit 15, the track servo is turned off and only the focus servo is turned on before starting writing and reading of information on the optical disk 1. Then, the maximum eccentricity of the loaded optical disc 1 and the phase φ indicating the positional relationship between the index signal 4 and the optical disc 1 are determined.

Next, the eccentricity information consisting of the maximum eccentricity and the phase φ is corrected by the eccentricity correction section 16 based on the mechanical and electrical delays and gains of the drive system of the positioner 5 and is added to the drive circuit 17. Outputs the applied waveform.

The above-described operation of the eccentricity information storage unit 15 and the eccentricity correction unit 16 will be described in detail with reference to FIGS. First, the details of the optical unit 60 will be described with reference to FIG. In FIG. 2, the optical unit 60 is shown by a dotted line. Laser light from a semiconductor laser 61 serving as a light source is converted into parallel light by a collimator lens 62, and is deflected by a beam splitter 63 to an optical path to an objective lens 11 mounted on an actuator 9. The objective lens 11 condenses the laser light near the recording layer 64 of the optical disc 1 and returns the reflected light modulated by the recording layer 64 to parallel light again. This parallel light passes through the beam splitter 63 and is condensed by the condenser lens 65, and enters the tracking error signal detector 12 composed of two photodiodes. In the tracking error signal detector 12, the output signal of each photodiode is input to the differential amplifier, and the difference is output as the tracking error signal 13.

In FIG. 2, a light amount detector for monitoring the light amount from the semiconductor laser 61 and a bending mirror for deflecting the optical path of the laser light are omitted, and the tracking error signal detector 12 is composed of two photodiodes. However, it may be constituted by four photodiodes.

Next, the relationship with the eccentricity information of the optical disc 1 will be described with reference to FIG. FIG. 3A is a diagram showing the optical disc 1, the positional relationship between the actuator 9 and the objective lens 11, and the track center DC and the rotation center RC of the optical disc 1. In this (A), the objective lens 11
Is fixed at a fixed position, that is, when the optical disc 1 is rotated without applying the track servo, the laser light from the objective lens 11 irradiates on the circumference indicated by the dotted line of the radius R centered on RC. become.

On the other hand, the track on the circumference of the radius R centered on the track center DC is shown by a solid line circle. At the position of the objective lens 11 shown in FIG. Irradiation with laser light is performed.

As described above, when the track center DC and the rotation center RC are eccentric by D, the point B is
When the objective lens 11 moves toward the rotation center RC of the optical disc 1 by the distance AB when the optical disk 1 comes to the position, the original track can be correctly irradiated with laser light.
When this distance is obtained using the rotation angle θ as a parameter, the distance AB is substantially D × cos θ regardless of the radial position of the track.

Therefore, as shown in FIG. 3B, the distance AB, that is, the amount of eccentricity, is represented by the amount of eccentricity on the vertical axis.
When the horizontal axis represents the rotation angle, a sine waveform is obtained.

Next, the maximum eccentricity D and the eccentricity of the optical disk 1 actually mounted and the phase φ of the index signal 4
Will be described with reference to FIGS. 4 and 5. FIG.

FIG. 4 shows the tracking error signal 13 and the index signal 4 detected by applying only the focus servo without applying the track servo and the index signal 4 as in FIG. These two signals and the clock are the input signals of the eccentricity information storage unit 15 shown in FIG.

In FIG. 4A, the tracking error signal 1
Numeral 3 changes with the period of the rotation frequency of the optical disk 1. During this one cycle T (from time t1 to t5), the optical disc 1
Tracking error signals 13 corresponding to the amount of eccentricity of
Is detected. From the number of zero crosses N and the track pitch Tp of the optical disc 1, the amount of eccentricity D is given by D =
(N × Tp) / 2.

On the other hand, with respect to the phase, t2 and t3 at which the interval of the zero cross becomes maximum are detected, the time t4 up to the midpoint is obtained, and the phase φ with the rising timing of the index signal 4 is obtained.

More specifically, in FIG. 5, after the tracking error signal 13 obtained when only the focus servo is applied without applying the track servo is converted into a digital signal by the analog / digital converter 30, the waveform analysis unit 31 The above-mentioned t2 and t3 to t4 are detected from the zero crossing point of the digitized tracking error signal 13, and the maximum eccentricity D and the phase φ are obtained. Next, the amplitude and phase of the sine wave stored as a table in the reference eccentric waveform storage unit 32 are corrected based on the maximum eccentric amount D and the phase φ. That is, the reference eccentric waveform storage unit 3
If the sine wave stored in 2 is sin θ, the sine wave is corrected to D × sin (θ−φ), and the corrected eccentric waveform is stored in the eccentric waveform storage unit 33 as a table.

Next, the eccentricity waveform stored in the eccentricity waveform storage unit 33 is further corrected by the eccentricity correction unit 16 based on the mechanical-electric conversion gain and phase of the system from the drive circuit 17 to the position of the objective lens 11. The corrected eccentric waveform (in the above example, D ′ × sin (θ−φ ′)) is stored in the form of a table.

Since the eccentricity information has been obtained as described above, the focus servo and the track servo are turned on, and the eccentricity corrector 16
The corrected sine waveform stored in the optical disk 1 is applied to the drive circuit 17 with the index signal 4 as a starting point, and the positioner 5 corrects the track position fluctuation due to the eccentricity.
To write and read information.

Here, without storing the corrected eccentric waveform as a table, the maximum eccentric amount D and the phase φ
The eccentricity may be obtained by calculation based on the eccentricity. In this case, it is only necessary to store the eccentricity and the phase as the eccentricity information.

Next, the positioner 5 will be described in detail with reference to FIG. In this embodiment, the positioner 5 is disposed on the lower surface of the optical disc 1 and supported by two guide shafts 40 so that the actuator 9 and the objective lens 11 can move smoothly in the radial direction of the optical disc 1. ing. An optical unit 60 and a tracking error signal detector 12 not shown in FIG. 6 are mounted in the positioner 5. Although the mounting directions of the rack 6, the pinion 7, and the rotary motor 8 are different between FIG. 1 and FIG. 6, it is preferable to mount and arrange the optical disk device in the direction shown in FIG.

Each function constituting the eccentricity information storage unit 15 described above may be constituted by an individual circuit, may be processed by a microprocessor, and may be further processed by a DSP.
May be executed. In addition to the fact that the eccentricity information is obtained first after the optical disc 1 is mounted, the eccentricity information may be obtained at regular intervals, or may be obtained at any time according to a command from a higher-level device. Further, the configuration may be such that writing and reading mistakes are counted, and if the number of errors exceeds a certain value, the eccentricity information is obtained again. With such a configuration, it is also possible to avoid erroneous correction of eccentricity due to a displacement between the optical disc 1 and the turntable 3.

The present invention described above can be applied to a magneto-optical disk drive using an external magnetic field device. Further, in the above description, the case where the reflected laser light from the optical disc 1 is used has been described. However, the present invention can be applied to the transmission type by adopting a configuration in which the incident side optical system and the light receiving side optical system are separated. It is possible to apply Further, although the optical system is mounted on the positioner 5, the present invention may be applied to a configuration in which a semiconductor laser and some optical components are separated from the positioner 5 and mounted in an optical disk device.

In this embodiment, the positioner 5 is moved linearly by the combination of the rack 6 and the pinion 7, but it may be constituted by using a lead screw. Further, as described later, a configuration in which the positioner 5 is swung is also preferable. It is preferable that either the rack 6 or the pinion 7 has a well-known structure for preventing backlash.

The first embodiment has the following advantages.

An inexpensive rotary motor 8 is used to move the positioner 5.
, And the fluctuation of the track position due to the eccentricity of the optical disk 1 can be corrected by moving the positioner 5. Therefore, cost reduction and high performance of the optical disk device can be achieved.

Further, since the positioner 5 is configured to follow the change in the track position based on the eccentricity, the amount of movement of the actuator 9 itself for following the eccentricity is reduced, and therefore the inclination of the objective lens 11 and the optical axis are reduced. Is reduced, and data recording / reproducing characteristics are improved.

Further, the actuator 9 and the positioner 5
Since the configuration is such that the eccentricity information is detected from the tracking error signal 13 without using a position sensor for detecting the relative position with respect to, the cost can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, when the position of the positioner 5 fluctuates due to vibration or the like, the actuator 9
The present invention is characterized in that a state in which an offset state is continued by an amount corresponding to the variation is prevented, and
It corresponds to.

As a signal detector for detecting a signal corresponding to the distance between the positioner 5 and the actuator 9 shown in FIG. 7, for example, a light-emitting element and two light-receiving elements are used to determine the amount of light received by each light-receiving element. Although a position sensor that directly detects the position of the actuator 9 from the difference may be used, in the second embodiment, the track servo unit 14 is used as the signal detection unit, and the low-pass filter 18 is used as the correction signal generation unit. ing.

That is, the actuator 9 is moved by a distance corresponding to the polarity and magnitude of the output current of the track servo unit 14.
Moves from the neutral position, the track servo unit 1
4 can be used as a position detection unit, and in this embodiment, a low-pass signal in the output signal of the track servo unit 14 is extracted and used as a correction signal. Therefore, the low-pass filter 18 is suitable as a correction signal generation unit.

Next, a second embodiment will be specifically described with reference to FIG.

When the tracking servo is turned on,
It is expected that the displacement of the positioner 5 will fluctuate due to disturbance such as vibration. At this time, if the tracking servo is applied, an offset current is added to the tracking coil 10 so that the actuator 9 is displaced in accordance with the fluctuation. If there is a displacement corresponding to this offset, the movable range of the actuator 9 is reduced, and the objective lens 1
Therefore, it is necessary to remove the displacement of the positioner 5 due to the disturbance.

For this purpose, the current flowing through the track king coil of the actuator 9, that is, the current corresponding to the distance between the positioner 5 and the actuator 9 in the track direction is detected from the output of the track servo unit 14, and the rotation frequency component is detected. A low-pass component is extracted by a low-pass filter 18 and input to the drive circuit 17 of the rotary motor 8 to remove displacement of the positioner 5 due to disturbance.

The displacement of the positioner 5 due to this disturbance is
In the embodiment, the configuration is such that the detection is performed from the current flowing through the tracking coil 10 as described above without providing a special position sensor.

Conditions for the positioner 5 to operate favorably so as to reduce the amount of eccentricity include the frequency characteristic of the drive transmission path from the rotary motor 8 to the positioner 5 in the vicinity of the rotational frequency component of the optical disk 1. That is, there is no resonance point.

This resonance point can be avoided by configuring the resonance frequency of the drive transmission path higher than the rotation frequency of the optical disc 1. Specifically, this is made possible by reducing the number of gear train stages. In the second embodiment, the number of gear stages is one of the pinion 7 and the rack 6. By increasing the resonance frequency of the drive transmission path, the rotation speed of the optical disc 1 can be increased.
It is possible to increase the transfer speed of writing and reading information with the optical disk 1.

Next, as a third embodiment, an embodiment of a swing type positioner will be described with reference to FIG.

As shown in FIG. 8, a positioner 50 is provided with a bearing portion 51 and a sector gear 52, and the sector gear 52 is driven to rotate by a driving gear 53 provided on a rotating shaft of the rotary motor 8,
The positioner 50 is swung about a shaft (not shown) rotatably fitted to the bearing portion 51 so that the actuator 9
Is moved in a direction crossing the track so that a predetermined track can be tracked.

Since the swing type positioner 50 can be driven without converting the rotation of the rotary motor 8 into a linear motion once, the power transmission efficiency is good and the power consumption can be reduced.

Further, it is not necessary to use a mechanical part such as a guide accompanying the swinging movement of the positioner 50, so that the cost can be reduced.

Next, a fourth embodiment will be described with reference to FIG. In the present embodiment, a closed loop feedback control system is added to the first embodiment, and the position control of the positioner is performed by increasing the gain of the control system at a frequency at which eccentricity of the optical disk occurs. . In general, the error of the feedback control system with respect to the target value can be reduced by increasing the gain of the system. However, in a system including elements of a mechanical system, the servo band is limited due to the mechanical resonance frequency of the system, so that the gain in this band is also limited. In this embodiment, it is noted that the eccentricity of the optical disk mainly occurs near the rotation frequency of the optical disk. By increasing only the gain of the feedback control system near the rotation frequency, the followability of the positioner near the rotation frequency is improved. It is intended to be improved.

In FIG. 9, each component of the portion surrounded by the dotted line is
This is almost the same as the first embodiment, and the same reference numerals are used for the same components, and the description is omitted. The part surrounded by the solid line is a part newly added in the present embodiment, which will be described below. The positioner of the present embodiment may be the linear positioner described above, but employs an oscillating positioner shown in FIG. 11 described later as a suitable positioner.

An encoder 75 is attached to a shaft 82 of the rotary motor 8. In this embodiment, a number of slits are provided on the concentric circle of the encoder 75. An optical sensor 74 having a light emitting element and a light receiving element is arranged adjacent to the encoder 75. Since the rotation angle of the rotary motor 8 can be detected from the number of output pulses of the light receiving element, and furthermore, in the present embodiment, a two-phase output having a phase difference of 90 ° is obtained, so that the rotational direction of the rotary motor 8 can also be detected. . Further, by multiplying the output pulse, the detection accuracy of the rotation angle can be improved.

In this embodiment, the rotation information of the rotary motor 8 is obtained optically, but a magnetic encoder may be used by utilizing the Hall effect.

In FIG. 9, the difference between the output SC of the eccentricity correction unit 16 and the output SE of the optical sensor 74 is added to the adder 76. This difference signal is input to the band-pass amplifier 78. In the band-pass amplifier 78, only a predetermined band component is amplified, and in this embodiment, a band component including the rotation frequency of the optical disc, that is, 60 Hz is amplified. This band may be changed according to a method of rotating the optical disk, that is, a rotation method such as a constant linear velocity or a constant zone linear velocity. FIG. 12 shows an example of the gain and phase characteristics of the bandpass amplifier 78.

In FIG. 9, the output of the band-pass amplifier 78 is input to the phase compensation filter 80. This phase compensation filter 80 is for stabilizing the control and reducing the steady-state error. More specifically, a phase margin at a phase angle of 180 ° is increased, and a gain in a low frequency range is increased.

Next, the output signal of the phase compensation filter 80 is input to the drive circuit 17 in the same manner as shown in FIG. The drive circuit 17 drives the rotary motor 8, so that the shaft 82 and the gear 84 are rotated.
The gear 84 is meshed with a gear 86 fixed to the positioner 50 (see FIG. 11).

The configuration surrounded by the solid line 72 in FIG. 10 reduces the difference between the signal SE and the signal SC without increasing the low-frequency gain of the system in which unnecessary mechanical resonance tends to occur. 50 moves synchronously with the eccentricity.
In the fourth embodiment, the bandpass amplifying unit and the phase compensating unit are implemented by circuits. However, the same processing may be performed by a microprocessor, or more preferably, by a DSP.
Further, in the present embodiment, processing is performed in the order of bandpass amplification and phase compensation, but conversely, processing may be performed in the order of phase compensation and bandpass amplification.

Next, a fifth embodiment is shown in FIG. In this embodiment, members having the same functions as those used in the first to fourth embodiments are denoted by the same reference numerals. This embodiment is an example of a double servo loop. The first loop is a system including the tracking error signal detector 12, the track servo unit 14, and the tracking coil 10, and forms a conventional tracking servo loop. The second loop includes a position sensor 88, a bandpass amplifier 78, a phase compensation filter 72, a drive circuit 17, a rotary motor 8, and gears 84 and 8.
6 and a positioner 50, which constitute a characteristic configuration of the present embodiment.

In the present embodiment, the position sensor 88 of the second loop is composed of a pair of a light emitting element and a light receiving element, and the relative position between the actuator and the positioner is changed by changing the amount of received light when the actuator moves in the track direction. A change is detected. The position sensor 88 detects a change in the distance between the objective lens and the positioner. The position signal PS indicating the distance change is transmitted to the bandpass amplifier 7.
8 is input. In the band-pass amplifier 78, only a signal in a predetermined frequency band is amplified as described above. The phase compensation filter 72, the drive circuit 17, the rotary motor 8, and the gears 84 and 86 operate as described above. In this embodiment, the position signal PS acts as an error signal, and the bandpass amplifier 78 amplifies a signal having an eccentric frequency. Thus, in the second loop, the positioner can move in synchronization with the eccentricity so as to reduce the error caused by the eccentricity.

The band pass amplifier 78 and the second loop will be described in more detail. 12A shows gain characteristics of a transfer function of the bandpass amplifier 78 with gain on the vertical axis and frequency on the horizontal axis, and FIG. 12B shows transmission with the frequency on the vertical axis and angle on the horizontal axis. It shows the phase characteristics of the function. Similarly, FIG. 13A shows the gain characteristic of the transfer function of the second loop, and FIG. 13B shows the phase characteristic. The transfer function of the loop surrounded by the solid line in the fourth embodiment also shows the same tendency as the characteristic of the loop transfer function in FIG.

As shown in FIG. 12A, the band-pass amplifier 78 in this embodiment has a rotation frequency of 6 which is the rotation frequency of the optical disk.
It has a peak at 0 Hz, and is amplified in a band only around 60 Hz. That is, only a signal having a frequency within a narrow band around 60 Hz is amplified by the band-pass amplifier 78. In this embodiment, the transfer function of the bandpass amplifier 78 is represented by the following equation.

[0082]

(Equation 1)

FIG. 9B shows the phase characteristic of the band-pass amplifier 78, which indicates that the band-pass amplifier 78 does not adversely affect the stability.

In the fifth embodiment, the band-pass amplifying unit and the phase compensating unit are implemented by circuits. However, the same processing may be performed by a microprocessor, or more preferably by a DSP. Furthermore, in the present embodiment, the processing is performed in the order of the band-pass amplification and the phase compensation. However, the processing may be performed in the order of the phase compensation and the band-pass amplification.

[0085]

According to the first aspect of the present invention, the rotational drive source is decelerated by the gear train to move the positioner, and the eccentricity of the optical disk can be corrected with a simple configuration. Can be reduced.

Further, since the amount of movement of the actuator can be reduced, the servo performance for following the light beam to a predetermined track is improved, the inclination of the objective lens can be reduced, and the displacement of the objective lens from the optical axis can be reduced. Data recording / reproducing characteristics are improved.

According to the second aspect of the invention, in addition to the effects of the first aspect, even when an offset of a low-frequency component occurs in the eccentricity correction output of the rotary motor, the moving amount of the offset can be reduced. In addition, by forming the gear train in one stage, the transmission loss can be reduced and the main resonance frequency of the positioner and the gear portion can be increased, so that stable operation of eccentricity correction can be performed. Also, by increasing the main resonance frequency, the rotation speed of the optical disk can be increased, and the data transfer speed with the optical disk can be increased.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, even if a position sensor is not provided, a change in the position of the actuator and the positioner is detected from the current flowing through the tracking coil. Costs can be reduced.

According to the fourth aspect of the present invention, since the swinging type optical disk apparatus in which the positioner is rotatable around one axis is configured, the positioner can be moved with a small number of parts, and the frictional portion can be gradually reduced. Positioner position control is facilitated.

According to the fifth aspect of the present invention, the eccentricity is corrected by the positioner using a feedback control system in which the amount of eccentricity is a target value and the amount of movement of the positioner is a control amount.
The control error can be gradually reduced. According to the invention of claim 6, the control error of the eccentricity correction by the positioner can be gradually reduced without widening the servo band by using a band-pass amplifier that amplifies only a predetermined band including the rotation frequency of the optical disk. It becomes possible.

According to the seventh aspect of the present invention, the control error of the eccentricity correction by the positioner without widening the servo band with a small number of components for amplifying the output signal of the position detecting sensor for detecting the positional relationship between the actuator and the positioner by the band-pass amplifier. Is gradually reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of a first embodiment.

FIG. 2 is a diagram showing a configuration around an actuator

FIG. 3 is a diagram illustrating an eccentricity

FIG. 4 is a diagram showing an example of a tracking error signal and an index signal.

FIG. 5 is a diagram showing a specific example of an eccentricity information storage unit;

FIG. 6 is a diagram showing an embodiment of a linear positioner.

FIG. 7 is a diagram showing a second embodiment.

FIG. 8 is a diagram showing a third embodiment.

FIG. 9 is a diagram showing a fourth embodiment.

FIG. 10 shows a fifth embodiment.

FIG. 11 is a diagram showing a positioner and an optical sensor;

FIG. 12 is a diagram illustrating an example of transfer function characteristics of a bandpass amplifier.

FIG. 13 is a diagram showing an example of a loop transfer function of a positioner servo system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Spindle motor 5 Positioner 6 Rack 7 Pinion 8 Rotary motor 9 Actuator 10 Tracking coil 11 Objective lens 12 Tracking error signal detector 14 Track servo unit 15 Eccentric information storage unit 16 Eccentricity correction unit 17 Drive circuit 74 Optical sensor 75 Encoder 78 Bandpass amplifier 80 Phase compensation filter

Claims (7)

[Claims] 1. An optical disk device on which an optical disk can be mounted, wherein a positioner having an actuator that enables a light beam irradiated on the optical disk to move in a direction crossing a track can be moved in a direction in which the actuator crosses the track. A rotation motor driven via a gear train, an output signal of a track shift detector for detecting a signal corresponding to a positional relationship between the light beam and the track, and an index signal generated each time the optical disc rotates. An eccentricity information storage unit for storing the amount of eccentricity and phase information of the optical disk, wherein when the light beam tracks the track,
An optical disc device, wherein the rotation motor is driven based on the eccentricity and phase information in the eccentricity information storage unit. 2. A signal detector for detecting a signal corresponding to a distance between the positioner and the actuator, and a correction for forming an eccentricity correction signal having a signal component lower than a predetermined frequency from an output signal of the signal detector. The optical disk device according to claim 1, further comprising a signal generation unit, wherein an output signal of the correction signal generation unit is added to a drive signal of the rotation motor to drive the rotation motor. 3. The optical disc device according to claim 2, wherein the signal detection unit detects a signal corresponding to the distance based on a current flowing through a tracking coil of the actuator. 4. The optical disk device according to claim 1, wherein the positioner is rotatably supported around a support shaft and has a sector gear having a gear center on an axis of the support shaft. An optical disk device, wherein the sector gear is driven by the rotation motor via a gear train. 5. The optical disk device according to claim 1, further comprising: a positioner position detecting means for detecting the position of the positioner; a band-pass amplifier for amplifying only a band including a predetermined frequency; and a phase compensator. A difference signal between the output of the eccentricity information storage unit and the output of the positioner position detection unit is amplified by the band-pass amplification unit, and the rotary motor is driven based on the signal phase-compensated by the phase compensation unit. Optical disk device. 6. The optical disk device according to claim 5, wherein the band-pass amplifier amplifies a signal in a frequency band including a rotation frequency of the optical disk. 7. An optical disk device capable of mounting an optical disk, a positioner having an actuator capable of moving a light beam irradiated on the optical disk in a direction crossing a track provided on the optical disk, and the actuator and the positioner. A position detection sensor that detects the positional relationship of the positioner, a rotary motor that moves and drives the positioner, a band-pass amplifier that amplifies only a band including a predetermined frequency, and a phase compensator. An optical disk device, wherein an output is amplified by the band-pass amplifier and the rotary motor is driven based on a signal phase-compensated by the phase compensator.