JP2008305487A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device advantages in securing the quality of a signal to be recorded on an optical disk and a signal to be reproduced therefrom irrespective of a rotation speed of the optical disk. <P>SOLUTION: A system controller 18 controls a spindle motor 12 via a servocontrol part 20, and rotates the optical disk 2 at a prescribed rotation speed (double-speed) to measure an amount of measurement radial skew. The system controller 18 sets the measured amount of measurement radial skew to a focus control part 52. The rotation speed (double-speed) is set to the servocontrol part 20 on the basis of a control command supplied from an external computer 28. The system controller 18 refers to a correction table 54, and corrects the amount of measurement radial skew by multiplying the amount of measurement radial skew by a correction coefficient α corresponding to the set rotation speed, obtains the corrected amount of measurement radial skew, and set the corrected amount of measurement radial skew to the servocontrol part 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus for recording and reproducing signals on an optical disc.

2. Description of the Related Art There is an optical disc apparatus that records or reproduces signals or records and reproduces an optical disc such as a DVD (Digital Versatile Disk) using an optical pickup.
An optical pickup forms a light spot on a signal recording surface of an optical disc by converging a light beam emitted from a light source with an objective lens.
By the way, if the central axis (optical axis) of the light beam (converged light) converged on the signal recording surface of the optical disc is not perpendicular to the signal recording surface, coma aberration occurs on the focal plane. The characteristics (jitter) of the reproduction signal will deteriorate.
In particular, as the recording density of the optical disk increases, the numerical aperture (NA value (Numerical Aperture)) of the objective lens increases, so the coma caused by the inclination of the central axis of the light beam with respect to the signal recording surface gradually increases. As a result, the deterioration of characteristics such as a reproduction signal becomes remarkable.
On the other hand, since an optical disk is manufactured by molding a synthetic resin material such as polycarbonate, it has a warp caused by manufacturing variations, humidity environment, and the like.
Therefore, when a light beam is irradiated from an optical pickup onto a warped optical disk, the above-mentioned coma aberration problem occurs and it is difficult to ensure the quality of a reproduction signal or the like.
In order to solve such a problem, the inclination (skew) of the surface of the optical disk or the signal recording surface is detected, and the relative inclination between the signal recording surface and the central axis of the light beam is corrected based on the detection result. Techniques have been proposed in which skew correction means is provided and control is performed so that the central axis of the light beam is always orthogonal to the signal recording surface (see Patent Documents 1, 2, and 3).
In this specification, the skew is a so-called radial skew, and is an optical disc that is displaced with a certain inclination in the thickness direction of the optical disc along a radial direction (radial direction) with respect to a plane orthogonal to the central axis of the optical disc. It shall be warped.
Japanese Patent Laid-Open No. 10-64096 JP 2002-298379 A JP 2005-1000049 A

By the way, conventionally, such skew correction operation detects skew while rotating the mounted optical disk at a specific rotation speed, for example, in the initialization operation performed when the optical disk is mounted on the optical disk apparatus. The skew correction amount is determined in accordance with the detected skew amount.
On the other hand, in many cases, an optical disc is configured to be able to record and / or reproduce at different rotational speeds. For example, DVD-Rs capable of recording at different rotational speeds such as 4 × speed, 8 × speed, 16 × speed, 18 × speed, and 20 × speed are provided.
When the optical disk is rotationally driven at different rotational speeds, the magnitude of the centrifugal force acting on the optical disk also differs depending on the rotational speed.
Since the optical disk is formed of a synthetic resin material or the like, the rigidity thereof is relatively low. Therefore, the warp of the optical disk, in other words, the amount of skew also changes according to the rotation speed. That is, the skew amount decreases as the rotation speed increases.
Therefore, when recording and / or reproduction is performed by rotating the optical disk at a rotation speed different from the rotation speed at the time of skew detection, the skew correction amount deviates from the optimum value, so that the quality of the reproduction signal and the like is ensured. There is a disadvantage above.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical disc apparatus that is advantageous in ensuring the quality of signals recorded and reproduced on an optical disc regardless of the rotational speed of the optical disc. There is.

  In order to achieve the above object, the present invention provides a driving means for holding and rotating an optical disk, and a signal recording surface of the optical disk that is rotationally driven by the driving means. An optical pickup for detecting a reflected light beam by reflected light on the signal recording surface of the beam, and controlling the incident angle of the light beam with respect to the signal recording surface of the optical disc according to a set radial skew amount An optical disk device comprising a skew control means, comprising: a correction means for correcting the radial skew amount set in the skew control means according to the rotational speed of the optical disk during recording and / or reproduction of the optical disk. It is characterized by that.

  According to the present invention, since the correction means for correcting the radial skew amount set in the skew control means according to the rotation speed of the optical disk at the time of recording and / or reproduction of the optical disk is provided, regardless of the rotation speed of the optical disk, This is advantageous in ensuring the quality of signals recorded on and reproduced from the optical disk.

(First embodiment)
Embodiments of an optical disc apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of an optical disc apparatus 10 according to the present embodiment.
As shown in FIG. 1, an optical disc apparatus 10 includes a spindle motor 12 as a driving unit that rotates and drives an optical disc 2 as an optical disc such as a CD-R, DVD ± R, or DVD-RAM, an optical pickup 14, and an optical pickup. And a feed motor 16 as drive means for moving 14 in the radial direction. Here, the spindle motor 12 is configured to be driven and controlled at a predetermined rotational speed by the system controller 18 and the servo control unit 20.

The signal modulation / demodulation unit and ECC block 22 modulate and demodulate the signal output from the signal processing unit 24 and add an ECC (error correction code). The optical pickup 14 irradiates the signal recording surface of the optical disc 2 rotating according to instructions from the system controller 18 and the servo control unit 20 with a light beam. Recording and reproduction of an optical signal with respect to the optical disc 2 is performed by such light irradiation.
Further, the optical pickup 14 can detect various light beams as will be described later based on the reflected light beam from the signal recording surface of the optical disc 2 and supply a signal corresponding to each light beam to the signal processing unit 24. It is configured.

The signal processing unit 24 is a servo control signal based on a detection signal corresponding to each light beam, that is, a focus error signal, a tracking error signal, an RF signal, and a monitor signal (hereinafter referred to as an R-OPC signal) necessary for running OPC processing. In other words, an ATIP signal required for controlling the rotation of the optical disc during recording can be generated. Further, predetermined processing such as demodulation and error correction processing based on these signals is performed by the servo control unit 20, the signal modulation unit, the ECC block 22, and the like according to the type of recording medium to be reproduced.
Here, if the recording signal demodulated by the signal modulation unit and the ECC block 22 is for data storage of a computer, for example, it is sent to an external computer 28 or the like via the interface 26. Accordingly, the external computer 28 and the like are configured to receive a signal recorded on the optical disc 2 as a reproduction signal.

If the recording signal demodulated by the signal modulation unit and the ECC block 22 is for audio / visual use, the digital / analog conversion is performed by the D / A conversion unit of the D / A and A / D converter 30, and the audio / visual conversion is performed. It is supplied to the processing unit 32. The audio / video processing unit 32 performs audio / video signal processing and transmits the audio / video signal to an external imaging / projection device via the audio / visual signal input / output unit 34.
A feed motor 16 is connected to the optical pickup 14, and the optical pickup 14 is moved to a predetermined recording track on the optical disc 2 by the rotation of the feed motor 16.
In addition to controlling the spindle motor 12 and the feed motor 16, the servo control unit 20 controls the focusing direction and tracking direction of the objective lens 40 (see FIG. 2) of the optical pickup 14 based on the focus error signal and the tracking error signal. Further, radial skew is controlled.
The laser control unit 36 controls a laser light source in the optical pickup 14.

Next, the configuration of the optical pickup 14 will be described.
FIG. 2 is a block diagram showing the configuration of the optical pickup 14 and the focus control unit 52.
The optical pickup 14 includes a base 38, an objective lens 40, and a lens holder 42 that holds the objective lens 40.
The base 38 is provided so as to be movable in the radial direction of the optical disc 2 by the feed motor 16.
The lens holder 42 is connected to the base 38 via a support member (not shown).
That is, the lens holder 42 can move in the focus direction which is the thickness direction of the optical disc 2 and the tracking direction which is the radial direction of the optical disc 2, and the optical axis (center axis) of the objective lens 40 is the signal recording of the optical disc 2. It is supported via the support member so as to be movable in a radial skew direction that is a direction inclined in the radial direction of the optical disc 2 with respect to the surface.

The optical pickup 14 is provided with a focus drive mechanism 44 that moves the objective lens 40 in the focus direction and a tracking drive mechanism (not shown) that moves the objective lens 40 in the tracking direction.
The tracking drive mechanism includes a tracking coil provided on the base 38 side and wound around an axis extending in the tracking direction, and a magnet provided on the lens holder 42 so as to face the tracking coil. The lens holder 42 is moved in the tracking direction by the magnetic interaction between the magnetic field generated by applying the drive signal and the magnetic field of the magnet, and conventionally known actuators of various structures can be adopted as such a tracking drive mechanism. is there.

The focus drive mechanism 44 includes two actuators, an inner peripheral actuator 46A provided on the inner side in the radial direction and an outer peripheral actuator 46B provided on the outer side in the radial direction, with the objective lens 40 sandwiched in the radial direction of the optical disc 2. It is configured.
In the present embodiment, the inner circumference side actuator 46A is opposed to the inner circumference side focus coil 48A and the inner circumference side focus coil 48A which are provided on the base 38 side and wound around an axis extending in the focus direction. It is comprised with the inner peripheral side magnet 50A provided in the lens holder 42. FIG.
The inner circumference side actuator 46A is supplied with a signal to the inner circumference side focus coil 48A and generates a magnetic interaction, so that the portion of the lens holder 42 located on the inner side in the radial direction of the optical disc 2 with respect to the objective lens 40 is in the focus direction. Move to.
The outer peripheral actuator 46B is provided on the lens holder 42 so as to face the outer peripheral focus coil 48B and the outer peripheral focus coil 48B wound around an axis line provided on the base 38 side and extending in the focus direction. It is comprised with the outer peripheral side magnet 50B.
The outer actuator 46B moves a portion of the lens holder 42 located in the radially outer side of the optical disc 2 with respect to the objective lens 2 in the focus direction when a signal is supplied to the outer peripheral focus coil 48B and magnetic interaction occurs. It is.
In the present embodiment, the inner circumference side actuator 46A and the outer circumference side actuator 46B provided on the outer side in the radial direction only differ in arrangement position, and the coils and magnets are the same.
Therefore, when the same focus drive signals are supplied to the inner periphery side focus coil 48A and the outer periphery side focus coil 48B, magnetic interactions of the same size occur in the inner periphery side actuator 46A and the outer periphery side actuator 46B, respectively. The objective lens 40 moves in the focus direction along the optical axis direction without tilting the optical axis.
Further, when a signal larger than the other is supplied to one of the inner peripheral side focus coil 48A and the outer peripheral side focus coil 48B, the magnitude of the magnetic interaction generated between the inner peripheral side actuator 46A and the outer peripheral side actuator 46B differs. As a result, the optical axis of the objective lens 40 is inclined in the radial direction, and the radial skew can be adjusted.
Therefore, in the present embodiment, there are two skew adjusting actuators for swinging the optical axis of the objective lens 40 in the radial direction of the optical disc 2, the inner peripheral side actuator 46A and the outer peripheral side actuator 46B. It consists of an actuator.

Next, the servo control unit 20 will be described.
The servo control unit 20 includes a focus control unit 52.
The focus control unit 52 supplies the focus drive signal to the inner peripheral focus coil 48A and the outer peripheral focus coil 48B based on the focus error signal, thereby causing the objective lens 40 to move in the focus direction.
Further, as will be described later, the focus controller 52 gives a difference to the focus drive signals supplied to the inner peripheral focus coil 48A and the outer peripheral focus coil 48B based on the radial skew amount set by the system controller 18. Thus, the radial skew of the objective lens 40 is changed.
Accordingly, in the present embodiment, the skew control means for controlling the incident angle of the light beam with respect to the signal recording surface of the optical disc 2 by the focus driving mechanism 44 and the focus control unit 52 according to the set radial skew amount. Is configured.

In the present embodiment, when the optical disc 2 is not warped and the signal recording surface of the optical disc 2 extends on a virtual plane orthogonal to the central axis of the optical disc 2, the objective lens 40 matches the signal recording surface. The focus drive mechanism 44 and the focus control unit 52 are configured such that the focus drive signal supplied to the inner peripheral focus coil 48A and the outer peripheral focus coil 48B becomes zero in this state.
Therefore, when the focus servo is applied and the objective lens 40 is in focus with respect to the signal recording surface of the optical disc 2, the value (voltage value) of the focus driving signal is the optical disc with respect to the virtual plane. 2 represents the amount of displacement displaced along the thickness direction.
In other words, the system controller 18 is configured to measure the radial skew amount of the optical disc 2, that is, the measured radial skew amount, by obtaining the value of the focus drive signal from the servo control unit 20 (focus control unit 52). Has been.

FIG. 3 is an explanatory diagram of the radial skew amount.
As shown in FIG. 3, two of an inner peripheral side position P1 located at a radial distance r1 on the signal recording surface P of the optical disc 2 and an outer peripheral side position P2 located at a radial distance r2 (> r1). The optical pickup 14 is moved to each point, and the value (voltage value) of the focus drive signal is measured at each position. In the figure, symbol X indicates a virtual plane orthogonal to the central axis of the optical disc 2.
Assume that the values (voltage values) of the focus drive signals at the inner peripheral side position P1 and the outer peripheral side position P2 are d1 and d2, respectively.
By obtaining such a result, a displacement amount ΔD (d2−d1) in the thickness direction with respect to the distance ΔL (= r2−r1) between the inner peripheral side position P1 and the outer peripheral side position P2 of the optical disc 2 is obtained. Thereby, the measurement radial skew amount can be obtained.
The radial skew amount, that is, the measured radial skew amount can be indicated by an angle θ formed by the signal recording surface P of the optical disc 2 with respect to the virtual plane X, and this angle θ is determined by a displacement amount ΔD with respect to the distance ΔL.
Therefore, in the present embodiment, the system controller 18, the focus drive mechanism 44, and the focus control unit 52 constitute a measurement unit that measures the measurement radial skew amount (angle θ).

As described above, the radial skew amount of the optical disc 2 changes so as to decrease as the rotational speed of the optical disc 2 increases.
This is because the optical disk 2 is molded of a synthetic resin material such as polycarbonate and has low rigidity, and therefore the centrifugal force acting on the optical disk 2 increases according to the rotational speed.
By the way, the rate of change of the radial skew amount with respect to the rotational speed of the optical disc 2 is almost determined by the material and physical dimensions of the optical disc 2, and the difference between the individual optical discs 2 can be almost ignored.
Therefore, in the present embodiment, a correction coefficient α corresponding to the rotation speed of the optical disc 2 is prepared as the correction table 54 (FIG. 2).
Then, the measurement radial skew amount is measured in a state where the optical disk 2 is rotated at a predetermined rotation speed.
Then, when the rotational speed to be actually used is determined, the system control 18 corrects the measured radial skew amount based on the correction coefficient α corresponding to the determined rotational speed to actually use the rotational speed. The amount of radial skew is calculated and set in the skew control means.
Therefore, in the present embodiment, the system controller 18 constitutes a correction unit that corrects the radial skew amount set in the skew control unit in accordance with the rotation speed of the optical disc during recording and / or reproduction of the optical disc 2. ing.

Such a correction coefficient α will be described.
FIG. 4 is a diagram for explaining the correction coefficient. The horizontal axis represents the rotation speed Vr (rpm) of the optical disc 2, and the vertical axis represents the correction coefficient α (arbitrary unit).
The radial skew amount Sk when the rotational speed Vr of the optical disc 2 is changed in advance over a certain range (for example, 50 rpm to 7500 rpm) is measured in advance.
A radial skew amount at a reference rotation speed Vr0 (for example, 1 × speed) is set as a reference radial skew amount Sk0.
Then, by dividing each radial skew amount at each rotational speed (for example, 2 × speed, 4 × speed,... N speed) by the reference radial skew amount Sk0, a correction coefficient α for each rotational speed is obtained as shown in FIG. can get.
That is, the radial skew amount at the actually used rotational speed can be calculated by multiplying the measured radial skew amount obtained at the reference rotational speed Vr0 by the correction coefficient α corresponding to the actually used rotational speed. it can.
In the present embodiment, the system controller 18 is provided with a correction table 54 that associates the correction coefficient α with the rotation speed. The correction table 54 is configured by non-volatile storage means such as an EEPROM, for example.
The correction table 54 may be prepared in accordance with the type of the optical disc 2, such as dimensions such as the diameter and thickness of the optical disc 2, the type of material constituting the optical disc 2, and the optical disc 2. The structure may be determined based on whether the structure is one sheet or a structure in which two sheets are bonded together.
In the present embodiment, as described above, the radial skew amount at the rotational speed that is actually used is obtained by multiplying the measured radial skew amount by the correction coefficient α.
However, the measurement radial skew amount correction method using the correction coefficient α is not limited to the method of multiplying the measurement radial skew amount by the correction coefficient α, and various conventionally known correction methods can be employed.

Next, the operation of the optical disc apparatus 10 will be described with reference to the flowchart of FIG.
The optical disk apparatus 10 is connected to the external computer 28 (FIG. 1) and executes a write / read operation according to a control command supplied from the external computer 28.
First, the processing starts when the optical disc 2 is loaded in the optical disc apparatus 10.
The system controller 18 determines the type of the loaded optical disk 2 (step S10).
In this discrimination operation, the optical pickup 14 performs a focus search on the signal recording surface of the optical disc 2 to measure the distance between the signal recording surface and the disc surface, and whether the optical disc 2 has a one-layer structure based on the distance. This is done by checking whether it has a two-layer structure, or by reading the identification information of the optical disc 2 by the optical pickup 14.

Next, the initialization operation is started.
First, the system controller 18 controls the spindle motor 12 via the servo control unit 20, and rotationally drives the optical disc 2 at a predetermined rotational speed (double speed) (step S12).
Usually, the predetermined rotation speed is lower than the rotation speed during a write operation or a read operation described later.
Next, the system controller 18 measures the measurement radial skew amount (step S14).
Here, as described above, the displacement amount ΔD (d2−d1) in the thickness direction with respect to the distance ΔL (= r2−r1) between the inner peripheral side position P1 and the outer peripheral side position P2 of the optical disc 2 is obtained, and the displacement amount is obtained. A measurement radial skew amount is measured by ΔD / distance ΔL.
The system controller 18 sets the measured radial skew amount in the focus control unit 52 (step S16).
The system controller 18 determines whether or not to perform a write operation or a read operation based on a control command supplied from the external computer 28 (step S18), and if it is determined that neither a write operation nor a read operation is performed. The process is terminated.
If it is determined that the write operation or the read operation is to be performed, the rotation speed (double speed) is set in the servo control unit 20 based on the control command supplied from the external computer 28 (step S20).
Next, the system controller 18 reads the correction coefficient α corresponding to the set rotation speed with reference to the correction table 54, and corrects the measured radial skew amount by multiplying the measured radial skew amount by the correction coefficient α. Then, a correction radial skew amount is obtained (step S22).
Then, the correction radial skew amount is set again in the servo control unit 20 (step S24).
Next, in step S18, a write operation or a read operation designated from the external computer 28 is executed (step S26), and a series of processes is terminated.
In step S22, if the rotational speed set in step S12 and the rotational speed set in step S20 are the same, the correction of the measured radial skew amount is unnecessary, so step S24 is skipped and step S26 is skipped. Migrate to

As described above, according to the present embodiment, the correction means for correcting the radial skew amount set in the skew control means according to the rotational speed of the optical disk 2 during recording and / or reproduction of the optical disk is provided. Regardless of the rotational speed of the optical disc 2, it is advantageous in securing the quality of signals recorded on and reproduced from the optical disc 2.
Further, in the present embodiment, the correction of the radial skew amount by the correcting unit is performed by correcting the measured radial skew amount measured by the measuring unit using a correction coefficient determined according to the rotation speed of the optical disc 2. Thus, the radial skew amount can be corrected easily and in a short time, which is advantageous for simplifying the control of the optical disc apparatus 10 and improving the operation speed.
Further, in the present embodiment, the measurement of the measurement radial skew amount by the measuring means is performed in a state where the objective lens 40 is focused on the signal recording surface of the optical disc 2 by applying the focus servo of the optical pickup 14. Since the operation is performed based on the drive signal, a sensor for detecting skew and a circuit for processing a detection signal detected from such a sensor are not required. Therefore, the configuration of the optical disc apparatus 10 is simplified and the control is simplified. This is advantageous in achieving this.

(Second Embodiment)
Next, a second embodiment will be described.
In the second embodiment, instead of measuring the radial skew amount of the optical disc 2, the radial skew amount that obtains the best quality of the detection signal generated based on the reflected light beam from the optical disc is obtained. Is different from that of the first embodiment in that it is corrected in accordance with the rotational speed of the optical disk 2.

That is, in the second embodiment, the system controller 18 rotates the optical disk 2 at a predetermined rotational speed by the driving means, and the light beam irradiated on the signal recording surface of the optical disk 2 from the optical pickup 14. It has a function of forcibly changing the incident angle.
Specifically, the system controller 18 forcibly changes the radial skew amount set in the skew control means to forcibly change the incident angle of the light beam applied to the signal recording surface of the optical disc 2 from the optical pickup 14. To change.
The change range of the incident angle is a range extending on both sides of the virtual line in a plane including a virtual line (normal line) orthogonal to the signal recording surface.
The system controller 18 has a function of evaluating the quality of a detection signal generated based on a reflected light beam obtained by reflecting the light beam on the signal recording surface of the optical disc 2.
The detection signal includes a pit reproduction signal recorded on the signal recording surface or a wobble signal detected corresponding to a wobble formed on a land or groove on the signal recording surface.
As the quality of the detection signal, for example, the jitter value of the detection signal can be used.

FIG. 6 is a diagram showing the relationship between the radial skew amount and the jitter value.
In FIG. 6, the horizontal axis is the radial skew amount, and the vertical axis is the jitter value.
Usually, when the radial skew amount is zero, the jitter value becomes minimum (best), and the jitter value tends to increase (deteriorate) as the radial skew amount changes in the positive direction or the negative direction.
Therefore, the radial skew amount corresponding to the best point of the jitter value can be specified by forcibly changing the radial skew amount (incident angle of the light beam).
Normally, the jitter value measurement points are limited to one point on the plus side of the radial skew amount and one point on the minus side, and the jitter signal value at the two obtained measurement points is set to the middle point. Control is simplified by obtaining the corresponding radial skew amount by calculation.

  Therefore, in the second embodiment, the optical disk 2 is rotationally driven at a predetermined rotational speed by the driving means, and the radial skew amount set in the skew control means is forcibly changed to change the optical light. An initial setting unit that changes the incident angle of the beam and sets the radial skew amount with which the quality of the detection signal generated based on the reflected light beam from the optical disc 2 is the best as the initial setting value in the skew control unit, The system controller 18 and the focus control unit 52 are configured.

  Further, the system controller 18 constitutes correction means for correcting the radial skew amount set in the skew control means in accordance with the rotational speed of the optical disc during recording and / or reproduction of the optical disc 2. This is the same as the embodiment.

FIG. 7 is an operation flowchart of the optical disk device 10 according to the second embodiment. The same steps as those in FIG. 5 showing the first embodiment are denoted by the same reference numerals and will be briefly described.
First, the processing starts when the optical disc 2 is loaded in the optical disc apparatus 10.
The system controller 18 determines the type of the loaded optical disk 2 (step S10).

Next, the initialization operation is started.
First, the system controller 18 controls the spindle motor 12 via the servo control unit 20, and rotationally drives the optical disc 2 at a predetermined rotational speed (double speed) (step S12).
The system controller 18 changes the incident angle of the light beam by forcibly changing the radial skew amount set in the skew control means, and generates a detection signal based on the reflected light beam from the optical disc 2. The radial skew amount with the best quality is specified (step S30).
Next, the radial skew amount that provides the best detection signal quality is set as an initial setting value in the skew control means (step S32).
The system controller 18 determines whether or not to perform a write operation or a read operation based on a control command supplied from the external computer 28 (step S18), and if it is determined that neither a write operation nor a read operation is performed. The process is terminated.
If it is determined that the write operation or the read operation is to be performed, the rotation speed (double speed) is set in the servo control unit 20 based on the control command supplied from the external computer 28 (step S20).
Next, the system controller 18 reads the correction coefficient α corresponding to the set rotation speed with reference to the correction table 54, and corrects the measured radial skew amount by multiplying the measured radial skew amount by the correction coefficient α. Then, a correction radial skew amount is obtained (step S22).
Then, the correction radial skew amount is set again in the servo control unit 20 (step S24).
Next, in step S18, a write operation or a read operation designated from the external computer 28 is executed (step S26), and a series of processes is terminated.
In step S22, if the rotational speed set in step S12 and the rotational speed set in step S20 are the same, the correction of the measured radial skew amount is unnecessary, so step S24 is skipped and step S26 is skipped. Migrate to

Also in the second embodiment, since the same correction means as in the first embodiment is provided, the signals recorded on the optical disc 2 and the signals to be reproduced are reproduced regardless of the rotation speed of the optical disc 2. This is advantageous in ensuring quality.
Further, the correction of the radial skew amount by the correction means is performed using a correction coefficient that is determined according to the rotational speed of the optical disc 2 as the radial skew amount as an initial setting value that is set so that the quality of the detection signal is the best. Therefore, the radial skew amount can be corrected easily and in a short time, which is advantageous in simplifying the control of the optical disc apparatus 10 and improving the operation speed.
Further, in the present embodiment, the radial skew amount that provides the best detection signal quality is set as the initial setting value in the skew control means, so that it is detected from a skew detection sensor or such a sensor. Since a circuit for processing the detection signal is not necessary, it is advantageous in simplifying the configuration of the optical disc apparatus 10 and simplifying the control.

In the embodiment, the skew control means for controlling the incident angle of the light beam with respect to the signal recording surface of the optical disc 2 in accordance with the set radial skew amount includes the inner peripheral actuator 46A and the outer peripheral actuator 46B. In the above description, the skew adjusting actuator including the two actuators is included.
However, as a configuration for controlling the incident angle of the light beam with respect to the signal recording surface of the optical disk 2, the objective lens 40 is arranged by tilting the optical path of the light beam disposed between the light source and the objective lens. And a tilt correction element that guides the optical pickup 14 so as to tilt the optical axis of the light beam that passes through the tilt correction element or guides the optical pickup 14 so as to be movable in the radial direction of the optical disc 2. Various conventionally well-known skew control mechanisms such as those in which the optical axis of the objective lens 40 is tilted together with the optical pickup 14 by tilting the guide shaft using a motor, a cam mechanism, or the like can be employed.

1 is a block diagram illustrating a schematic configuration of an optical disc device 10 according to a first embodiment. 2 is a block diagram showing the configuration of an optical pickup 14 and a focus control unit 52. FIG. It is explanatory drawing of the amount of radial skew. It is a diagram explaining a correction coefficient. 3 is an operation flowchart of the optical disc apparatus 10 according to the first embodiment. It is a diagram which shows the relationship between radial skew amount and a jitter value. It is an operation | movement flowchart of the optical disk apparatus 10 of 2nd Embodiment.

Explanation of symbols

  2 ... Optical disk, 10 ... Optical disk device, 12 ... Spindle motor, 14 ... Optical pickup, 18 ... System controller, 40 ... Objective lens, 52 ... Focus control unit, 54 ... Correction table.

Claims (12)

Driving means for holding and rotating the optical disc;
An optical pickup that irradiates a signal recording surface of the optical disk that is rotationally driven by the driving means, and detects a reflected light beam by reflected light on the signal recording surface of the irradiated light beam;
An optical disc apparatus comprising skew control means for controlling an incident angle of the light beam with respect to a signal recording surface of the optical disc according to a set radial skew amount;
Correction means for correcting the radial skew amount set in the skew control means according to the rotational speed of the optical disc at the time of recording and / or reproduction of the optical disc,
An optical disc device characterized by the above. A measuring unit for measuring a radial skew amount of the optical disc that is rotationally driven by the driving unit at a predetermined rotation speed and generating a measuring radial skew amount;
The correction of the radial skew amount by the correcting unit is performed by correcting the measured radial skew amount measured by the measuring unit using a correction coefficient determined according to the rotation speed of the optical disc.
2. The optical disk apparatus according to claim 1, wherein The correction using the correction coefficient of the radial skew amount by the correction means is performed using a correction table in which the rotation speed of the optical disc and the correction coefficient corresponding to the rotation speed are stored in association with each other.
3. The optical disk apparatus according to claim 2, wherein The optical pickup is
An objective lens for irradiating the optical disk with the light beam;
A focus actuator that moves the objective lens in the optical axis direction based on a supplied focus drive signal;
The measurement radial skew amount is measured by the measurement means based on the focus drive signal detected in a state where the objective lens is in focus with respect to the signal recording surface by applying the focus servo of the optical pickup. The
2. The optical disk apparatus according to claim 1, wherein The optical pickup is
An objective lens for irradiating the optical disk with the light beam;
A focus actuator that moves the objective lens in the optical axis direction based on a supplied focus drive signal;
The distance in the radial direction between the inner circumferential side position and the outer circumferential side position where the radial distances of the signal recording surface of the optical disc are different from each other is ΔL,
The magnitude of the focus drive signal detected when the objective lens is in focus with respect to the signal recording surface by applying the focus servo of the optical pickup at the inner peripheral side position is d1,
When the magnitude of the focus drive signal detected when the objective lens is focused on the signal recording surface by applying the focus servo of the optical pickup at the outer peripheral side position is d2.
Measurement of the measurement radial skew amount by the measurement unit is performed based on the distance ΔL and the difference between the magnitudes of the two focus drive signals (d2−d1).
2. The optical disk apparatus according to claim 1, wherein The optical disk is rotated at a predetermined rotational speed by the driving means, and the incident angle of the light beam is changed by forcibly changing the radial skew amount set in the skew control means. An initial setting means for setting the radial skew amount, which is the best quality of the detection signal generated based on the reflected light beam from, as the initial setting value in the skew control means,
The correction of the radial skew amount by the correction unit is performed by correcting the initial setting value set by the initial setting unit using a correction coefficient determined according to the rotation speed of the optical disc.
2. The optical disk apparatus according to claim 1, wherein The correction using the correction coefficient of the radial skew amount by the correction means is performed using a correction table in which the rotation speed of the optical disc and the correction coefficient corresponding to the rotation speed are stored in association with each other.
The optical disc apparatus according to claim 6. The detection signal is a reproduction signal generated based on a pit formed on the signal recording surface;
The optical disc apparatus according to claim 6. The detection signal is a wobble signal generated based on a wobble formed on the signal recording surface;
The optical disc apparatus according to claim 6. The detection signal is a reproduction signal generated based on pits formed on the signal recording surface,
The quality of the detection signal is jitter of the reproduction signal;
The optical disc apparatus according to claim 6. The detection signal is a wobble signal generated based on a wobble formed on the signal recording surface,
The quality of the detection signal is jitter of the wobble signal;
The optical disc apparatus according to claim 6. The optical pickup is
An objective lens for irradiating the optical disk with the light beam;
A skew adjusting actuator that swings the optical axis of the objective lens in the radial direction of the optical disc;
The skew control means is configured to include the skew adjusting actuator.
2. The optical disk apparatus according to claim 1, wherein

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