JP2001167454A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device performing the control operation for eliminating the amount of the shift of an objective lens due to a spirally formed track when the tracking of the objective lens is made on the disk. SOLUTION: The rotation speed of a thread motor 5 is detected in a speed/ moving distance arithmetic circuit 12 by detection signals P1, P2 from Hall elements 11a, 11b, and a speed signal E corresponding to this detected rotation speed is produced. And, after a difference signal is produced by an operational amplifier 94 from a tracking error signal TE or a shift signal SFS showing the shifted amount of the objective lens and the speed signal E, this difference signal is amplified by an amplifier 95. By means of driving the thread motor 5 with a PWM drive 14 based on the difference signal which is PWM processed by a PWM signal producing circuit 13, the speed of the thread motor 5 is controlled in accordance with the deviated amount of the objective lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device for recording and reproducing a disk as a recording medium, and more particularly to a disk device having an optical pickup for recording and reproducing data on the disk.

[0002]

2. Description of the Related Art Conventionally, when an objective lens in an optical pickup is made to follow a track of a disk, a light detection signal obtained by the optical pickup is generated from reflected light of a laser beam applied to the track of the disk. An actuator provided in the optical pickup is controlled so that the tracking error signal becomes zero.
This tracking error signal is a signal indicating whether the object lens is deviating from the center position of the track that the objective lens follows, or the amount of deviation. That is, a tracking drive signal for driving the actuator is generated from the tracking error signal, and the actuator is driven by the tracking drive signal to move the objective lens finely in the radial direction of the disk to follow the track being reproduced or recorded. Let it.

As described above, the tracking of the objective lens is controlled. When the track of the disk having the spiral track is made to follow, the shift amount which is the shift amount between the optical axis of the light source and the optical axis of the objective lens. However, it gradually increases with the time made to follow. Therefore, in order for the objective lens to follow the track, a tracking drive signal that makes this shift amount zero is necessary. In the above-described tracking control, the tracking is performed with the objective lens deviated from the center position of the track. Will follow.

The tracking error signal corresponding to the shift amount is generated when the objective lens follows the state shifted by the shift amount, and the tracking drive signal is generated by the generated drive signal. You. Since the objective lens driven by the tracking drive signal is displaced from the optical axis of the light source, a laser beam is applied to a position slightly displaced from the center position of the track.

As the shift amount increases,
The deviation amount between the laser beam irradiation position and the center position of the track increases. If this becomes too large, the reliability of the signal received by the optical pickup will be reduced. In other words, so that this amount of deviation does not become too large,
When a certain amount of deviation occurs, it is necessary to make the deviation between the optical axis of the light source and the optical axis of the objective lens zero. In order to eliminate such a shift amount, a method of moving an optical pickup by a sled motor in a direction in which the deviation is eliminated has been used.

[0006]

However, when this sled motor is used, the cogging which is caused to rotate for the first time when a predetermined voltage is applied and which rotates by a predetermined angle or more when the predetermined voltage is applied. Because of the presence of the cogging, the rotation of the sled motor cannot be controlled at a rotation angle equal to or less than a predetermined angle due to the cogging. Therefore, conventionally, the tracking drive signal increases as the shift amount of the objective lens increases, and when the tracking drive signal reaches a voltage that overcomes cogging, the thread motor is rotated by the amount of cogging to make the shift amount zero, The operation of performing tracking by the tracking error signal again was repeated.

For example, in a compact disc reproducing apparatus, the amount of movement of the objective lens over one cogging of such a sled motor is approximately 200 μm.
Now, the track width of the tracked disk is 1.6μ
Assuming m, the sled motor starts rotating when the optical axis shift of about 120 tracks appears, and the shift amount is returned to zero. In recent years, there has been a demand for high-density recording of discs.
When tracking is performed on a disk having a diameter of μm by the above-described method, when a shift of the optical axis corresponding to about 400 tracks appears, the thread motor rotates and the shift amount is returned to zero. As described above, since the shift of the optical axis increases as the shift amount increases, the shift between the irradiation position of the laser beam and the center position of the track also increases. Therefore, when the track width is small, this deviation cannot be ignored in terms of the reliability of the reproduced signal.

Therefore, it is conceivable to increase the degree of amplification of the tracking drive signal. However, since the amount of rotation of the sled motor is substantially unchanged due to cogging, the sled motor passes through a position where the shift amount is zero. It is also conceivable to increase the speed reduction ratio of the intermediate transmission member of the optical pickup from the sled motor. At this time, for example, if the amount of movement to overcome the cogging is to be reduced to 1/10 from 200 μm to 20 μm, it is necessary to increase the reduction ratio by 10. However, since the movement amount of 200 μm in the compact disk reproducing apparatus is a sufficiently decelerated value, it is difficult to further increase the reduction ratio.
Even if such a reduction ratio can be realized, it takes a long time to perform a seek operation such as a long search, and the seek time required in recent years cannot be reduced.

When tracking using this cogging is performed, it is necessary to constantly supply a signal obtained by amplifying the tracking drive signal to the sled motor. However, this signal is not used except at the moment when the sled motor is rotated to overcome cogging. Therefore, the power that is constantly consumed by this signal is converted into heat that is mostly wasted.

The objective lens in the optical pickup is indicated by an elastic body having a high spring constant. Therefore, it is affected by gravity. Therefore, in a portable disk device or the like, when gravity is applied in the radial direction of the disk, the objective lens is displaced under the influence of the gravity. Therefore, the optical axis of the objective lens and the optical axis of the light source are shifted. When the reproduction is started in this state, the tracking is started with the shift amount being zero in this state. The deviation due to the influence of gravity cannot be ignored in terms of the reliability of the reproduced signal.

When data is recorded on a disk on which data is recorded by laser strobe magnetic field modulation, which will be described later, due to the displacement due to the influence of gravity, the position shifted from the track recognized by the device due to the influence of gravity. Has an objective lens. Therefore, data cannot be recorded unless the magnetic field reaches the track corresponding to the amount of the shift. Therefore, it is necessary to increase the diameter of the coil of the magnetic head that generates this magnetic field. However, increasing the coil diameter of the magnetic head in this way increases the power consumed, and also increases the generation of unnecessary radiation of the magnetic field by the magnetic head.

In view of such a problem, the present invention provides a disk device which performs a control operation for eliminating a shift amount of an objective lens due to a track formed in a spiral shape when tracking an objective lens on a disk. The purpose is to provide. Another object of the present invention is to provide a disk device that can eliminate the influence of an external force such as gravity applied to an objective lens. Another object of the present invention is to provide a disk device having a control operation for reducing the shift amount of an objective lens when tracking a disk having a narrow track width.

[0013]

In order to achieve the above object, a disk drive according to the present invention comprises: an optical pickup for irradiating a disk as a data recording medium with a laser beam; An objective lens for converging a laser beam on a track of the disk, an objective lens moving means for moving the objective lens in a radial direction of the disk, and a tracking error signal for generating a tracking error signal from a light detection signal output by the optical pickup Generating means; tracking servo means for operating the objective lens moving means in accordance with the tracking error signal given from the tracking error signal generating means to cause the objective lens to follow the track of the disk; and Moved radially at high speed A disk device for recording or reproducing data by irradiating a laser beam from the optical pickup to a track of the disk, and detecting a rotation speed of the thread motor and a speed signal. Speed signal generating means for generating the tracking error signal, and a difference signal generating means for receiving the speed signal and the tracking error signal and generating a difference signal representing a difference between the two signals. Based on the above, while operating the objective lens moving means by the tracking servo means, based on the difference signal generated by the difference signal generating means, by driving the thread motor,
The objective lens may follow a track of the disk.

In such a disk device, when recording or reproducing a disk on which a spiral track is formed, the objective lens follows the track. At this time, the tracking control using the tracking error signal is performed by the tracking servo means, and the actuator in the optical pickup is driven to follow the objective lens. However, since the track has a spiral shape, when the objective lens is moved only by the tracking control, the track is shifted from the objective lens and the track.
At this time, by controlling the speed of the sled motor according to the shift amount indicated by the tracking error signal, the objective lens is made to follow the center position of the track to be tracked.

Further, the disk device of the present invention comprises an optical pickup for irradiating a disk as a data recording medium with a laser beam, and an objective lens provided in the optical pickup and for converging the laser beam on a track of the disk. An objective lens moving means for moving the objective lens in the radial direction of the disk; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; Tracking servo means for operating the objective lens moving means in response to the tracking error signal to cause the objective lens to follow the track of the disc; and a sled motor for moving the optical pickup at high speed in the radial direction of the disc. Having, before In a disk device for recording or reproducing data by irradiating a laser beam from an optical pickup onto a track of the disk, a speed signal generating means for detecting a rotation speed of the thread motor and generating a speed signal; And a shift signal generating means for generating a shift signal indicating a shift amount of the optical axis of the objective lens from a light source optical axis of the laser beam, and the speed signal and the shift signal. And a difference signal generating means for generating a difference signal representing the difference between the two signals, wherein the tracking servo means operates the objective lens moving means based on the tracking error signal, Based on the difference signal generated by the signal generation means, the thread motor By moving, characterized in that to follow the objective lens in the track of the disk.

In such a disk apparatus, when recording or reproducing a disk having tracks formed in a spiral shape, an objective lens is made to follow the tracks. At this time, the tracking control using the tracking error signal is performed by the tracking servo means, and the actuator in the optical pickup is driven to follow the objective lens. However, since the track has a spiral shape, when the objective lens is moved only by the tracking control, the optical axis of the objective lens is shifted from the optical axis of the light source. At this time, by controlling the speed of the sled motor according to the shift amount indicated by the shift signal, the objective lens is made to follow the center position of the track to be tracked.

At this time, the laser beam emitted from the optical pickup to the disc comprises a main beam focused on a read track and sub-beams focused on two tracks adjacent to both sides of the read track. A light detection signal obtained from the reflected light of the main beam and the two sub-beams is given to the shift signal generating means, and the light detection signal based on the reflected light of the two sub-beams is added to the shift signal generating means. A shift signal is generated by adding the sum signal of the light detection signals.

Further, a light detection signal obtained from the reflected light of the main beam and the two sub-beams is given from the optical pickup to the tracking error signal generating means. A tracking error signal is generated by subtracting the sum signal of the light detection signals due to the reflected light of the two sub beams from the signal.

Further, the disk device of the present invention comprises an optical pickup for irradiating a disk as a data recording medium with a laser beam, and an objective lens provided in the optical pickup and for converging the laser beam on a track of the disk. An objective lens moving means for moving the objective lens in the radial direction of the disk; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; Tracking servo means for operating the objective lens moving means in response to the tracking error signal to cause the objective lens to follow the track of the disc; and a sled motor for moving the optical pickup at high speed in the radial direction of the disc. Having, before In a disk device for recording or reproducing data by irradiating a laser beam from an optical pickup onto a track of the disk, a plurality of Hall elements for detecting a rotation speed of the sled motor, and a plurality of detections from the plurality of Hall elements A differential means for differentiating the signals, and a plurality of differential signals obtained by differentiating the plurality of detection signals by the differentiating means, respectively, into absolute values, and positive or negative according to the rotation direction of the thread motor. Absolute value means for giving a polarity of the following, an adding means for adding a plurality of signals output from the absolute value means, a signal from the adding means and the tracking error signal, and the two signals And a difference signal generating means for generating a difference signal representing a difference between the tracking error signal and the tracking error signal. Operating the objective lens moving means by the servo control means, and driving the sled motor based on the difference signal generated by the difference signal generating means to cause the objective lens to follow the track of the disk. Features.

Further, the disk device of the present invention is an optical pickup for irradiating a disk as a data recording medium with a laser beam, and an objective lens provided in the optical pickup and for converging the laser beam on a track of the disk. An objective lens moving means for moving the objective lens in the radial direction of the disk; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; A tracking servo means for operating the objective lens moving means in response to the tracking error signal to cause the objective lens to follow the track of the disc; and a sled motor for moving the optical pickup at high speed in the radial direction of the disc. Having, before In a disk device for recording or reproducing data by irradiating a laser beam onto a track of the disk from an optical pickup, light of the objective lens from a light source optical axis of the laser beam is obtained from a light detection signal output by the optical pickup. Shift signal generating means for generating a shift signal representing the shift amount of the shaft, a plurality of Hall elements for detecting the rotation speed of the sled motor, and a plurality of detection signals from the plurality of Hall elements,
Differentiating means for differentiating, and absolute values giving a positive or negative polarity according to the rotation direction of the sled motor, while respectively converting a plurality of differential signals obtained by differentiating the plurality of detection signals by the differentiating means into absolute values. Value converting means, adding means for adding a plurality of signals output from the absolute value converting means, and a difference signal which is provided with the signal from the adding means and the shift signal and represents a difference between the two signals. And a difference signal generating means for generating the difference signal, and operating the objective lens moving means by the tracking servo means based on the tracking error signal, and based on the difference signal generated by the difference signal generating means. By driving the thread motor, the objective lens follows the track of the disk.

[0021]

Embodiments of the present invention will be described with reference to the drawings.

<Structure of Disk Device> First, the structure of the disk device will be described with reference to a block diagram showing the relationship between the internal structure of the disk device and the disk shown in FIG.
1 includes an optical pickup 2 for tracking a disk 1, an optical pickup 2 and a disk 1.
The optical pickup 2 and the magnetic head 3 both move in the radial direction of the disk 1. This optical pickup 2
Then, the recording of the disk 1 is performed by the magnetic head 3 and the reproduction of the disk 1 is performed by the optical pickup 2.

The optical pickup 2 moves the disk 1 in the radial direction by an intermediate transmission means (not shown) which converts the rotational drive of the sled motor 5 into a linear drive. The thread motor 5 is provided with a PWM (Pulse Width Modula).
tion) Driven by a sled motor drive signal from the driver 14. In the thread motor 5, a magnet (not shown) on a ring in which N poles and S poles are alternately magnetized, and Hall elements 11a and 11b are provided.

The Hall elements 11a and 11b are provided at predetermined intervals, and their outputs are sent to a speed / movement distance calculation circuit 12. The speed / movement distance calculation circuit 12 calculates the movement speed and the movement distance of the optical pickup 2 in the radial direction of the disk 1 based on the outputs from the Hall elements 11a and 11b. The calculation result of the moving speed is sent to the digital servo processing circuit 10 constituted by a DSP (Digital Signal Processor), and the calculation result of the movement distance is sent to the control microcomputer 8. The digital servo processing circuit 10 generates a signal for operating each control system based on the calculation result and a signal processed from a signal from the RF processing circuit 6 described later. The PWM signal generated by the PWM signal generation circuit 13 based on this signal is sent to the PWM driver 14, and a thread motor drive signal is generated.

The magnetic head 3 is moved by the head motor 16 in a direction perpendicular to the disk surface of the disk 1. That is, at the time of recording on the disk 1, the magnetic head 3
The head motor 16 is driven by the magnetic head lifting / lowering drive circuit 18 so that the head is lowered. When the recording is completed, the head motor 16 is driven by the magnetic head lifting / lowering drive circuit 18 so that the magnetic head 3 rises in the direction away from the disk 1.

As described above, when the magnetic head 3 is moved by the head motor 16 so as to be in sliding contact with the disk 1, the head drive circuit 17 is operated by the data signal supplied from the signal processing circuit 9. The magnetic head 3 is driven by the head driving circuit 17 to generate a magnetic field corresponding to the data signal given from the signal processing circuit 9 to the disk 1, and the recording operation on the disk 1 is performed.

A signal which is optically detected by the optical pickup 2 and output as a current signal is output by the RF processing circuit 6.
It is converted to a voltage signal. Among the signals output to the RF processing circuit 6, the light detection signal corresponding to the RF signal having data is composed of two signals having exactly opposite phases. Therefore, when this light detection signal is sent to the RF processing circuit 6, after differentially amplifying the two signals, the AGC (Automatic
tic Gain Control) processing and is sent to the signal processing circuit 9.

In the signal processing circuit 9, error correction, deinterleaving, and NRZI (Non-Return-to-Ze
ro Invert), decoded by Viterbi decoding, or the like, sent to the interface 20, and output to the outside. In this way, the data in the disk 1 is reproduced. When data is input from the outside via the interface 20, the data is converted into an encoded data signal by the signal processing circuit 9, and the data signal is transmitted to the head driving circuit 17. Sent out. After the data signal is sent to the head drive circuit 17 in this manner, as described above, the head drive circuit 17 drives the magnetic head 3 according to the data signal, thereby performing recording on the disk 1.

In the digital servo processing circuit 10, R
A synchronization signal obtained from the F signal is converted to a PLL (Phase Locked Loop) based on a master clock serving as a fundamental frequency signal.
It is processed. The signal subjected to the PLL processing is PW
After the PWM processing in the M signal generation circuit 13, the rotation of the spindle motor 4 is controlled via the spindle motor driver 15. The spindle motor 4 is a motor for moving the disk 1 in the circumferential direction. When performing a tracking operation for recording / reproducing the disk 1,
PLL control as described above is performed. The spindle motor 4 is controlled by an FG (Frequency Generator) servo when starting rotation of the disk or performing a long search for a track.

The FG servo will be described below. A drive signal is given from the spindle motor driver 15 to the spindle motor 4, and the spindle motor 4 is driven to rotate. At this time, a signal relating to the rotation of the motor itself is fed back from the spindle motor 4 to the spindle motor driver 15, and the FG signal generated by shaping the waveform of the fed-back signal is sent to the signal processing circuit 9. In the signal processing circuit 9, the FG signal is compared with the rotation speed of the spindle motor 4 at the position where the optical pickup 2 is currently tracking, and an error signal is generated. Based on the error signal, a signal for driving the spindle motor 4 is generated in the digital servo processing circuit 10, subjected to PWM processing by the PWM signal generation circuit 13, and then supplied to the spindle motor driver 15. FG servo is performed by such a loop.

The FG signal generated by the spindle motor driver 15 is also supplied to the control microcomputer 8.
From the FG signal given in this way, the spindle motor 4
When the rotation speed of the spindle motor 4 is lower than the desired rotation speed of the zone where the optical pickup 2 is located by a predetermined value or more, the control microcomputer 8 controls the disk of the laser beam. The irradiation of 1 is forcibly stopped.

On the other hand, an error signal such as a tracking error signal and a focus error signal optically detected by the optical pickup 2 is processed by the RF processing circuit 6 and then subjected to A / D conversion.
The signal is converted into a digital signal by the converter 7. This digital signal is sent to the digital servo processing circuit 10.
After the signal processed by the digital servo processing circuit 10 is subjected to PWM processing by the PWM signal generation circuit 13,
The sled motor 5 and an actuator (not shown) in the optical pickup 2 are driven via the M driver 14 to perform focus control and tracking control.

The tracking servo for performing the tracking control is performed by the optical pickup 2 → the RF processing circuit 6 →
AD converter 7 → digital servo processing circuit 10 → PW
M signal generation circuit 13 → PWM driver 14 → main loop of optical pickup 2 or thread motor 5, and Hall elements 11a, 11b → speed / movement distance calculation circuit 12
→ Digital servo processing circuit 10 → PWM signal generation circuit 1
3 → PWM driver 14 → optical pickup 2 or thread motor 5

Further, this disk device includes an LD (Laser Diode) driver 31 for controlling the output of a laser output from a laser diode 41 (FIG. 5) described later;
A lead-in switch 32 which is a mechanical switch such as a limit switch serving as a position detecting means serving as a reference for obtaining an absolute position between the disk 1 and the optical pickup 2 is provided.

In the disk device having such a configuration,
A control circuit 19 is constituted by the control microcomputer 8, the signal processing circuit 9, the digital servo processing circuit 10, and the PWM signal generation circuit 13.

<Disk> Next, the configuration of the disk 1 will be described below with reference to the drawings. FIG. 2 is a plan view showing the configuration of the recording area of the disk 1. FIG.
FIG. 3 is a diagram showing a configuration of a track on the disk 1. FIG. 4 is a diagram showing the relationship between the super-resolution layer and the recording layer formed on the disk 1.

This disk 1 is a disk recorded by laser strobe magnetic field modulation recording. That is,
A predetermined portion of the disk 1 is heated to a temperature equal to or higher than the Curie point based on a laser beam which receives a magnetic field from the magnetic head 3 (FIG. 1) and emits a pulse from the optical pickup 2 (FIG. 1). Perpendicular magnetization based on the direction of the magnetic field received from Thereafter, when the temperature of the recording portion magnetized in this way drops to a temperature below the Curie point, the magnetization is fixed and held at the magnetization oriented as described above. Since the emitted laser beam is pulsed light, the pitch of the recorded signal is very narrow, and high-density recording is possible.

First, the configuration of the disk 1 will be described with reference to FIG. The disk 1 has a spindle fitting hole 25 for fitting to the shaft of the spindle motor 4 (FIG. 1) at the center position, and a mirror area 21a in which no signal is recorded at the outermost and innermost portions, respectively. , 21b are formed. Then, a lead-in area 22 is provided on the inner peripheral side of the mirror area 21a, and a lead-out area 24 is provided on the outer peripheral side of the mirror area 21b. The lead-in area 22 extends from the inner peripheral side of the lead-in area 22 to the outer peripheral side of the lead-out area 24. In the area,
A main information area 23 for recording data is formed.

The lead-in area 22 is also a TOC area, in which a wobble described later is formed. This TO
The C (Table Of Contents) area is used by a disk manufacturer to store TO information such as manufacturing information such as optimum power of a laser beam at the time of disk recording and reproduction at the time of disk manufacturing.
This is an area where C information is recorded, and the TOC information is repeatedly recorded. Such TOC information is already recorded when the user gets it, and cannot be deleted. This lead-in area 22 is hereinafter referred to as “TOC area 22”.

Further, the main information area 23 has a plurality of divided zones. The disc 1 in which a plurality of zones are formed as described above is a zone CLV (Constant Lin
Rotation control is performed by earVelocity) control. The zone CLV control is controlled so that the rotation speed is constant in each zone, and the fixed rotation speed of each zone is determined so that the linear velocities between the zones are substantially equal. That is, in each zone, CAV (Constant
Angular Velocity) control is performed, and CLV control is performed between zones. Therefore, the fixed rotation speed is lower in the zone on the outer peripheral side.

The TOC area 22 is also subjected to the same zone CLV control as that of the main information area 23.
The rotation speed of the area 22 is controlled at the lowest rotation speed in all the information recording areas. In the present embodiment,
The main information area 23 in the disc 1 is assumed to be divided into ten zones. Also, the TOC area 22
Corresponds to zone 0.

When the disk 1 having such a structure is mounted on a disk device, first, the optical pickup 2 (FIG. 1)
Performs the reading of the TOC area 22 and the TO
Grasp C information. After reading the TOC information, the disk device enters a state where recording and reproduction can be started, that is, a standby state. Note that the time from the mounting of the disk 1 to the standby state is hereinafter referred to as “standby time”.

As described above, when reading the TOC area 22, in order to enable the reading,
The rotation speed of the disk must be a predetermined rotation speed. At this time, since the TOC area 22 is located at the outermost periphery of the information recording area of the disk 1 and its fixed rotation speed is set to the lowest, the startup of the spindle motor 4 (FIG. 1) is accelerated. Therefore, the standby time can be reduced. Further, since the TOC area 22 is provided on the outer peripheral portion, reading of the TOC area 22 is also advantageous for the eccentricity of the disk 1, and the time required for reading the TOC information is reduced.

Next, the configuration of tracks on the disk 1 will be described with reference to FIG. The disk 1 has one groove formed spirally from the outermost periphery to the innermost periphery. Conversely, lands are formed spirally from the outermost periphery to the innermost periphery. The grooves and lands formed in this manner are alternately detected when the optical pickup 2 (FIG. 1) moves in the radial direction of the disk 1. The widths of the groove and the land are substantially equal to each other, for example, so that both are approximately 0.5 μm. Hereinafter, the width of the groove and the land will be described as P, respectively.

The groove and land thus formed are used as recordable tracks. That is, as shown in FIG. 3B, recording tracks composed of grooves and recording tracks composed of lands are provided alternately. FIG. 3A is a diagram showing the relationship between grooves and lands formed in the circumferential direction of the disk 1, and arrows indicate the inner circumferential direction. FIG. 3B is a cross-sectional view taken along line MM ′ of FIG. 3A. Hereinafter, the recording track formed by the land is referred to as “track A”, and the recording track formed by the groove is referred to as “track B”. At this time, the pitch between tracks A and B is 2P, respectively, but the pitch between adjacent tracks is P. Hereinafter, the configuration of the track in the main information area 23 will be described.

When such a track is formed, the tracks A and B have lands and grooves disappear at predetermined intervals. The disappearance portions of the land and the groove become the clock marks 26a and 26b, respectively.
The clock mark 26a formed on the track A has the same height as the groove, and its width S is set to be smaller than the diameter of the beam spot formed on the disk 1. By doing so, at the time of detecting the clock mark, the portion where the detection signal becomes zero is not continuous. That is, at the time of detection of the clock mark, the point of zero crossing is one point. Track B
Is formed at the same height as the land, and the width thereof is S as with the clock mark 26a.

Therefore, when reproducing the track A or the track B, since the phases of the signals when the respective clock marks 26a and 26b are detected are different, it is possible to confirm which track is being reproduced. This means that when recording track A or track B,
The same is true. Such clock marks 26a, 26b
Are formed between the clock marks 26a or the clock marks 26b in the tracks A and B, respectively, where the data portions 27a and 27b are formed. Each of the data sections 27a and 27b is
Form one frame.

A wobble 28a is formed on the side wall of one of the 55 data portions 27a forming one frame. In the data part 27a, the data part following the data part in which the wobble 28a is formed has a side wall opposite to the side wall in which the wobble 28a is formed.
A wobble 28b is formed. This wobble 28a, 2
8b is formed for recording address information. The address data indicated by the wobble 28a is called a "preceding address", and the address data indicated by the wobble 28b is called a "second address".

The two data sections in which such wobbles 28a and 28b are formed are called "address data sections", and the remaining 53 data sections are called "main data sections". In track B, wobbles 28a and 28b are formed on the inner wall of data section 27b.
One data part is called “address data part” and the remaining five
The three data parts are called “main data part”. Therefore,
One frame is formed by two address data parts and 53 main data parts. Then, every 16 frames are processed as one information group, and this information group is called a block. The number of blocks per track differs depending on the position of the track, and the number of tracks on the inner peripheral side of the disk 1 decreases.

The zone number, the block number, and the frame number are recorded in the address data portion.
Based on the data in this address data section, recording, playback,
Each mode such as search is performed. In addition, since such data is recorded by forming a wobble in the address data portion, the data is recorded regardless of whether the track A as a land or the track B as a groove is tracked. Can be read. Further, when writing data to the main data portion, information for clarifying which track of track A or track B data is being written is recorded together with the data as the main information. .

When a track is constructed in this way, the zone number, block number, and frame number, which are the position information of the track A on the outermost side in FIG. 3, are a, b, and c, respectively. The ADIP data to be represented is (a, b, c). Therefore, the ADIP data of the next frame on the same track is (a, b, c +
1). Now, assuming that the number of blocks of one track in this zone is n, the ADIP data of the frame of the next track A facing the frame (a, b, c) is
(A, b + n, c). In FIG. 3, for convenience, there is no shift between the opposing frames, but actually, a shift of several frames occurs.
Assuming that this shift corresponds to α frames, (a, b +
n, c + α). Also, the shift of this α frame is
It is a known value for each track, and in the disk device, a data table is prepared in the control microcomputer 8 (FIG. 1).

The ADIP data is encoded, and is recorded as a leading address and a trailing address on the wobbles 28a and 28b on the respective side walls by biphase mark modulation. That is, the track is determined based on whether the data of the preceding address and the data of the following address are the same or different. When ADIP data is read in order to recognize the frame address while tracking the track A, the reproduction signals of the preceding address and the following address have opposite phases. However, since the preceding address and the following address are signals subjected to bi-phase mark modulation, information indicating the same frame address is continuously read when tracking the track A.

On the other hand, when the ADIP data is read to recognize the frame address while tracking the track B, first, the wobble 28a on the outer peripheral side is read.
Is read, and then the subsequent address is read by the inner wobble 28b. At this time, for example, when the data of the preceding address becomes (a, b, c), the data of the following address becomes (a, b + n, c) (as described above, the frame shift for each track). Occurs, α frames for the shift are considered.)

As described above, if the data of the preceding address by the wobble 28a and the data of the subsequent address by the wobble 28b are the same, the track A is tracked,
Also, the preceding address of the wobble 28a and the wobble 28
If the data of the subsequent address by b is different, it means that track B is being tracked. Therefore, by reading the ADIP data, it is possible to confirm whether the track of the land is tracked or the track of the groove is tracked.

Tracks are formed in the main information area 23 in this manner. Similarly, the TOC area 22 also has a track A formed of lands and a track B formed of grooves. B is provided with a clock mark and a data portion. Then, as in the main information area 23, one frame is formed by two address data parts and 53 main data parts, and the two address data are a wobble as a preceding address and a subsequent address. A wobble is formed.

Further, T at which such a track is formed
In the OC area 22, a wobble is also formed in the main data section on the same side wall as the side wall on which the wobble serving as the preceding address is formed. That is, it is formed on the side wall opposite to the side wall on which the wobble serving as the subsequent address is formed, and is not formed alternately like the address data. Therefore, the data based on the wobble is recorded only on one of the two consecutive tracks. Note that, in the TOC area 22 recorded in this manner, as described above, the TO
Since the C information is repeatedly recorded, it is not necessary to read all of the information.

Also, since the wobble of the main data portion is formed only on one side wall of the land, the number of repetitions of the recorded TOC information is smaller than that for recording the TOC information for each track. Looks like However, as described above, data can be read from this wobble regardless of whether track A formed by a land or track B formed by a groove is tracked. This means that the TOC information is recorded in both B.

As will be described later, when shifting from track A to track B, or when performing the reverse operation, the tracking servo control is performed by inverting the phase of the tracking error signal. In the TOC area 22, the optical pickup 2
When the tracking error signal is for track A (FIG. 1), when the tracking error signal is for track A, the signal of the same phase is used. When the tracking error signal is for track B, the signal whose phase is inverted is used. Is used. By changing the tracking error signal in this way, the TOC information can be read without shifting tracks.

Therefore, for example, it is assumed that when the disk device reads the TOC information during the standby time, it has been previously determined that the tracking error signal for the track A should be used. At this time, when the optical pickup 2 (FIG. 1) is moved to the TOC area 22 and the arrival point is the track B, the tracking is performed without moving the optical pickup to the track A adjacent to the track B. The TOC information can be read by inverting the phase of the error signal.

In the TOC region 22 configured as described above,
Data may be written. At this time, T
In the OC area 22, since a wobble is also formed in a data portion forming a main data portion for writing data, the SN ratio is deteriorated, and it becomes difficult to read data written in the data portion. However, the effect of wobble can be reduced by lowering the recording density of the data to be written in the data portion and recording the data. For example, by recording at a recording density that is approximately half the recording density of data to be recorded in the main data section of the main information area 23, the effect of wobble can be greatly reduced.

When the TOC area 22 in which data has been written in this way is reproduced, the reproduced signal is obtained by superimposing the light amount change signal due to the wobble on the main data. It is possible to eliminate a light amount change signal due to high frequency wobble. By doing so, the effect of wobble can be removed from the written data.

When data is written in the TOC area 22 as described above, the data to be written may be, for example, user TOC (UTOC) information. This UT
For example, when music information is recorded on the disc 1, the OC information is music information such as a start position and an end position of the music to be recorded. By grasping the UTOC information serving as such music information, the OC information is obtained. The user can select a song to be played from the songs recorded in the.

Therefore, the UTOC information is also necessary at the time of reproducing the disc 1, and is read together with the TOC information during the standby time. Since the TOC information recorded by wobble in the TOC area 22 and the UTOC information written in the main data section can be simultaneously read, the standby time is shorter than when the TOC information and the UTOC information are read individually. .

Further, regarding the relationship between the super-resolution layer and the recording layer,
This will be described with reference to FIG. The disk 1 is provided with a super-resolution layer on the side irradiated with a laser beam from the optical pickup 2 (FIG. 1) and a recording layer on the side to which the magnetic head 3 (FIG. 1) is slid. When the super-resolution layer of the disk 1 has not reached the Curie point, as shown in FIG.
The magnetization direction of the super-resolution layer is in the horizontal direction. still,
In FIG. 4, N and S of the recording layer, arrows, and arrows of the super-resolution layer indicate the direction of magnetization, and are drawn in 1-bit units. A signal obtained by reproducing a recording unit magnetized by N of the recording layer is called an "N signal", and a signal reproduced by a recording unit magnetized by S of the recording layer is called an "S signal".

The Curie point of the super-resolution layer is lower than the Curie point of the recording layer. Therefore, when a laser beam is irradiated from the optical pickup 2 (FIG. 1) during reproduction of the disk 1, the output of the laser beam is higher than the Curie point of the super-resolution layer because the temperature of the 1-bit recording unit is higher than the Curie point. The power is controlled to be lower than the Curie point of the layer. When a laser beam is emitted from the optical pickup 2 (FIG. 1) during recording, the output of the laser beam is power-controlled so that the temperature of the 1-bit recording unit becomes higher than the Curie point of the recording layer. You.

First, the operation at the time of reproduction will be described below. The optical pickup 2 (FIG. 1) irradiates the super-resolution layer of the disk 1 with a laser beam whose power is controlled so as to be an output during reproduction as described above. Then, as shown in FIG. 4B or 4C, the super-resolution layer is perpendicularly magnetized according to the direction of magnetization of the recording layer immediately above the super-resolution layer.
Thereby, the polarization plane of the reflected light of the laser beam undergoes rotation according to the direction in which it is magnetized. However, since the data recorded on the recording layer is recorded at a high density, the spot diameter of the spot generated by irradiating the laser beam is larger than the recording unit and corresponds to a 3-bit recording unit. That is, spots are formed in 3-bit units. Note that the spot generated by this laser beam is called a “light spot”.

Now, in FIG. 4B, assuming that the super-resolution layer does not exist, the 3-bit recording unit of the recording layer on which the light spot is formed has one N-magnetized recording unit. Since there are two bits of the recording unit magnetized in S and S, the S signal is reproduced as the recording unit magnetized in S, although the recording unit actually magnetized in N is reproduced. However, by providing the super-resolution layer, the location where the super-resolution layer reaches the Curie point is only the target recording unit for one bit.

Therefore, in FIG. 4B, the polarization plane of the reflected light is rotated by the recording unit magnetized to N,
The signal is reproduced. In addition, the place which reaches the Curie point in this way is called a "heat spot". Further, in FIG. 4C, since the 1-bit recording unit corresponding to the heat spot formed at the position located at the center of the light spot is magnetized to S, the S signal is reproduced.

Next, the operation at the time of recording will be described below. From the optical pickup 2 (FIG. 1), a laser beam whose power is controlled so as to be an output during recording as described above is irradiated on the super-resolution layer of the disk 1, and the super-resolution layer is
It is perpendicularly magnetized as shown in FIG. At this time, since the magnetic head 3 (FIG. 1) slides and a magnetic field is applied, the recording layer is also vertically magnetized by the magnetic field of the magnetic head 3 as shown in FIG. That is, in FIG.
When a magnetic field of N is applied by the magnetic head 3 as shown in FIG.

At this time, in FIG. 4D, although the spot diameter of the heat spot on the super-resolution layer is large, the spot diameter of the heat spot exceeding the Curie point of the recording layer is large enough to correspond to a 1-bit recording unit. It will be. Therefore, the perpendicular magnetization by the magnetic head 3 (FIG. 1) is performed only on the target recording unit for one bit.

As described above, both lands and grooves are used as recording tracks.
By providing the OC area 22 and recording data also in the TOC area 22, the diameter is substantially reduced.
It has become possible to record data of a recording capacity of about 1 Gbyte on a 50 mm disk. (Note that a floppy disk is 1.44 Mbyte and a 120 mm diameter CD (Compact Disk) is 65
A 0 Mbyte mini disk with a diameter of 64 mm is 140 Mbyte. )

<Structure of Optical Pickup> The optical pickup 2 will be described below with reference to the drawings. FIG.
FIG. 1 is an external perspective view showing a configuration of an optical pickup 2.
The optical pickup 2 emits a laser beam from the laser diode 41 to the center position of a target track on the disk 1. This laser beam first enters the first diffraction grating 42 composed of a hologram element. In the first diffraction grating 42, one main beam of zero-order light and two
A sub-beam of the next light is generated. The main beam and the sub-beam are respectively transmitted by PBS (Polarizing beam splitter).
tter) 45, the light enters the objective lens 44 via the collimator lens 43 which converts these beams into parallel light.

The objective lens 44 is controlled by an actuator (not shown) to move in the radial direction of the disk 1 based on the tracking error signal. The main beam entering the objective lens 44 forms a main spot at the center position of a target track on the disk 1, and the two sub-beams entering the objective lens 44
In each case, a sub-spot is formed at the center position of the track on both sides of the track on which the main spot is formed.

At the time of reproducing or recording the main data portion, the temperature of the super-resolution layer (FIG. 4) reaches the Curie point due to the heat spot (FIG. 4) formed by the main beam, and the perpendicular magnetization is generated based on the recorded data. The plane of polarization of the light reflected from the disk 1 is rotated according to the direction of the magnetization of the recording layer (FIG. 4) of the disk 1. The reflected light whose polarization plane is rotated by the direction of magnetization of the heat spot (FIG. 4) formed on the main spot on the disk 1 passes through the objective lens 44 and the collimator lens 43 and the PBS 45.
Light enters. At this time, the sub-beams incident on the respective tracks on both sides of the target track are:
The light reflected by the sub-spot passes through the objective lens 44 and the collimator lens 43 and enters the PBS 45 in the same manner as the light reflected from the main spot.

As described above, a part of the reflected light of the main beam and the sub-beam incident on the PBS 45 is partly split into a part of the reflected light.
The light enters the beam 9 and its traveling direction is changed by the second diffraction grating 49. The reflected light that has passed through the second diffraction grating 49 in this way enters the second photodetector 50. Further, in the second photodetector 50, an optical signal for generating a tracking error signal or a focus error signal based on the Foucault method is generated from the incident reflected light.

The remaining reflected light obtained by splitting the reflected light of the main beam and the sub-beam entering the PBS 45 is 9
The traveling direction can be changed by 0 °, and the light enters the Wollaston prism 46. The reflected light that has entered the Wollaston prism 46 in this way has a different traveling direction according to the rotation given to the polarization plane when the disk is reflected. Then, the reflected light passing through the Wollaston prism 46 enters the first photodetector 48 composed of two photodiodes (not shown) forming a pair via the concave lens 47.

At this time, the above-mentioned reflected lights having different traveling directions are incident on the two photodiodes provided in the first photodetector 48, respectively. When the reflected light is incident on these two photodiodes, the first photodetector 48 generates a current signal corresponding to each of the reflected light and sends it to the RF processing circuit 6 (FIG. 1). The current signals generated by the reflected lights having different traveling directions are signals having phases opposite to each other, and are RF signals obtained by reproducing data recorded in the main data portion corresponding to the S signal and the N signal.

As described above, when the laser beam passes through the optical pickup 2, the output of the laser beam emitted from the laser diode 41 is increased during recording in order to raise the temperature of the recording layer to a Curie point or higher. Must be greater than the output of Also, during recording, the output of the laser beam is greater than during playback,
Since the levels of the reflected light incident on the first photodetector 48 and the second photodetector 50 also increase, the levels of the RF signal and the optical signal also increase. Therefore, in each circuit after the optical pickup 2 that processes these signals, switching is performed so that the gain is smaller than that during reproduction.

As described above, the TOC of the disc 1
When recording UTOC information or the like in the area 22 (FIG. 2), in order to reduce the recording density, the time interval of the emission pulse of the laser beam emitted from the laser diode 41 of the optical pickup 2 is increased. . That is, by increasing the period of the light emission pulse and decreasing the frequency of the light emission pulse, the recording density of the data recorded in the TOC area 22 (FIG. 2) can be reduced. Make it smaller than the recording density.

<Search Operation When Disk is Mounted> The search operation when the disk 1 is mounted on the disk device will be described with reference to FIGS. When the disk 1 is mounted on the disk device, first, as described above, T
The OC area 22 is searched. The search is to move the optical pickup 2 and the objective lens 44 to a target track. When the TOC area 22 is searched as described above, the TC recorded in the TOC area 22 is searched.
The OC information and the UTOC information are read, and the disk device enters a standby state.

At this time, in order to shorten the standby time, the optical pickup 2 moves the TOC area 22 as soon as possible.
, It is necessary that the optical pickup 2 can reach the TOC region 22 only by the rough search or the rough search. Hereinafter, each of the rough search and the rough search will be described.

In the coarse search, the number of tracks that must be traversed is calculated by comparing address data between the position of the track where the optical pickup 2 is located and the position of the target track. The sled motor 5 (FIG. 1) is caused to reach near the target track position based on the calculation result.

The rough search is a search means that operates more coarsely than the coarse search described above.
This rough search is generally used to move the optical pickup 2 to the optical pickup 2. In this rough search, TOC is not performed without calculating the number of crossing tracks as in the coarse search.
When the optical pickup 2 reaches the area 22, the lead-in switch 32 provided opposite to the disk 1 is switched to stop the rotation of the sled motor 5 (FIG. 1).

If the optical pickup 2 attempts to reach the TOC area 22 by performing such a rough search or a rough search only once in order to shorten the standby time, the operation of the TOC area is rough because the search means is a rough operation. It is necessary to make the width of 22 about 2 mm. However, in the disc 1 for high-density recording, the above TOC
The width of the region 22 will be very large. Therefore, when such TOC area 22 is used only for the TOC information, a useless space is widened.

Therefore, as described above, by making it possible to write data such as UTOC information in the TOC area 22, the recording capacity of the data can be increased. When the data recorded in the TOC area 22 is read out as described above, since the recording density of the recorded data is low, the high-frequency light amount change signal due to the wobble is removed by a low-pass filter. The recorded data can be read.

Thus, the UTOC information is stored in the TOC area 22.
Since it is necessary to read the UTOC information from the disc recorded in the above, it is necessary to perform a normal search instead of the rough search in which the search is performed by the lead-in switch 32 (FIG. 1). As described above, since the normal search is performed, the T.sub.T is compared with the disc in which the UTOC information is not stored in the TOC area 22 searched by the rough search.
The width of the OC region 22 can be reduced. Also, TO
According to the disk in which the UTOC information is stored in the C area 22, the TOC information and the UTOC information are read at once, so that the standby time can be reduced.

<Signal Processing of Optical Signal Detected by Second Photodetector> The signal processing operation of the optical signal detected by the second photodetector 50 will be described with reference to the drawings. FIG.
FIG. 7 is a diagram showing a positional relationship between an incident position of a laser beam passing through a diffraction grating 49 and a second photodetector 50.

As described above, the reflected light of the main beam and the sub beam from the disk 1 (FIG. 5) is
(FIG. 5), the primary light of a part of the reflected light is changed in course by the second diffraction grating 49 and enters the second photodetector 50. As shown in FIG. 6, the second diffraction grating 49 includes three diffraction gratings A, B1, and B2 having different polarization directions. Depending on the polarization directions of the diffraction gratings A, B1, and B2, the reflected light of the main beam and the sub-beam split by the PBS 45 is focused on a predetermined position in the second photodetector 50.

The second photodetector 50 includes a photodiode group Da including photodiodes D1 and D2, a photodiode group Db including photodiodes E1, E2 and E3, and photodiodes F1, F2 and F3. And a photodiode group Dc. In such a second photodetector 50, the reflected light of the main beam passing through the diffraction grating A is condensed at the boundary between the diodes D1 and D2 of the photodiode group Da, and the difference between the light amounts of the diodes D1 and D2. Becomes a focus error signal.

The reflected light of the main beam passing through the diffraction grating B1 is reflected by the diode F1 of the photodiode group Dc.
And the reflected lights of the two sub-beams are respectively focused on the diodes F2 and F3 of the photodiode group Dc. Further, the reflected light of the main beam passing through the diffraction grating B2 is applied to the diode E1 of the photodiode group Db.
Light reflected by the two sub-beams is focused on the diodes E2 and E3 of the photodiode group Db, respectively.

At this time, the difference between the light amounts of the diodes E1 and F1 on which the reflected light of the main beam is incident and the diodes E2 and F2 on which the reflected light of the sub-beam is incident on the track on the right of the track on which the main beam is incident. A tracking error signal and a shift signal to be described later are generated using the difference between the light amounts of the diodes E3 and F3 on which the reflected light of the sub beam is incident on the track on the left of the track on which the main beam enters. Is done.

<Generation of Tracking Error Signal and Shift Signal> The operation of generating the tracking error signal and the shift signal will be described with reference to the drawings. FIG. 7 is a diagram showing a relationship between a main spot and a sub spot formed on a track of the disk 1 and a circuit for generating a tracking error signal and a shift signal.

Track A (land) and track B (groove) are alternately arranged on a disk 1 in which the track pitch is continuously set to P. As shown in FIG. In this case, the main beam is emitted from the optical pickup 2 (FIG. 1) to the track A, and a main spot 51 is formed. In addition, one of the two sub-beams is applied to the track B adjacent to the right side of the track A where the main spot 51 is formed, and the sub-spot 52 is formed. Further, the other of the two sub-beams is applied to the track B adjacent to the left side of the track A where the main spot 51 is formed, and the sub-spot 53 is formed.

The main spot 51 thus formed
As described above, the reflected light from the sub-spots 52 and 53 is split by the PBS 45 (FIG. 5), passes through the second diffraction grating 49 (FIG. 6), and enters the second photodetector 50. Is done. At this time, as shown in FIG. 7, the reflected light at the four portions corresponding to the quarter circle obtained by dividing the main spot 51 into four equal parts is the photodiodes D1, D2, E1, respectively.
It is incident on F1. Also, the reflected lights at two portions corresponding to the half circle where the sub spot 52 is bisected are incident on the photodiodes E2 and F2, respectively. Further, reflected light at two portions corresponding to a half circle where the sub spot 53 is bisected is a photodiode E3, respectively.
It is incident on F3.

The photodiodes D1, D2, E1,
The values of the current signals output by E2, E3, F1, F2, and F3 are d1, d2, e1, e2, and e, respectively.
3, f1, f2, and f3. In FIG. 7, the photodiodes D1, D2, E1, E2, E3, F1, F
2 and F3 are drawn so as to correspond to the main spot 51 and the sub spots 52 and 53 for convenience, and the actual configuration is as shown in FIG.

Thus, the values are d1, d2, e1, e
Current signals of 2, e3, f1, f2, and f3 are sent to the RF processing circuit 6. In the RF processing circuit 6, the current signals of the photodiodes E1 and F1 are respectively supplied to the positive-phase input terminal a and the negative-phase input terminal b of the operational amplifier 54, and the current signals of the photodiodes E2 and F2 are respectively supplied to the positive-phase input terminal of the operational amplifier 55. The current signals of the photodiodes E3 and F3 are supplied to the terminal a and the negative-phase input terminal b, respectively.
6 are sent to the positive-phase input terminal a and the negative-phase input terminal b.
Then, in the operational amplifiers 54, 55, 56, the difference signals TE1, TE
2, voltage signals corresponding to TE3 are output from the respective output terminals.

The difference signals TE1, TE2, TE3 obtained by the operational amplifiers 54, 55, 56 are as follows. TE1 = e1-f1 TE2 = e2-f2 TE3 = e3-f3

Then, the difference signal TE3 obtained by the operational amplifier 56 is multiplied by G2 by the multiplier 57 to obtain G2 · TE
A voltage signal corresponding to 3 is sent to the adder 58. In the adder 58, the difference signal T obtained by the operational amplifier 56 is obtained.
By adding E2, a voltage signal corresponding to TE2 + G2 · TE3 is generated and sent to the multiplier 59.
Then, in the multiplier 59, G1 is multiplied, and G1 ·
A voltage signal corresponding to (TE2 + G2 · TE3) is generated and sent to the negative-phase input terminal b of the operational amplifier 60 and the positive-phase input terminal b of the operational amplifier 61.

A voltage signal corresponding to the difference signal TE1 is sent out to the positive-phase input terminals a of the operational amplifiers 60 and 61. The operational amplifier 60 and the operational amplifier 6
No. 1 outputs a tracking error signal TE and a shift signal SFS from an output terminal. The tracking error signal TE and the shift signal SFS are obtained by the following equations. TE = TE1-G1 · (TE2 + G2 · TE3) SFS = TE1 + G1 · (TE2 + G2 · TE3)

The tracking error signal TE obtained in this manner is calculated by the multipliers G2 and G2 in the multipliers 57 and 59.
By selecting G1 to an appropriate value, a tracking error signal having no offset is obtained. In the present embodiment, such a differential push-pull method (DPP method: Diff
erential Push-Pull method) is used to determine the tracking error signal TE.

The DPP method will be briefly described below. As is well known, when tracks are formed in a spiral shape on a disk, and when performing tracking control when performing recording or reproduction on the disk, the objective lens is
Deviates from the center of the track. Such a shift amount of the objective lens is called a shift amount, and an electric signal corresponding to the shift amount is called an offset. Hereinafter, offsets generated in the main spot 51 and the sub spots 52 and 53 are represented by B1, B2 and B3, and the difference signals TE1 and T3.
The amplitudes of E2 and TE3 are A1, A2 and A3, and the shift amount of the objective lens is X.

When the values are determined in this manner, the pitch between the tracks is P, so that the difference signals TE1, TE
2 and TE3 are respectively represented by the following equations. TE1 = A1 · SIN (πX / P) + B1 TE2 = A2 · SIN (π (XP) / P) + B2 TE3 = A3 · SIN (π (X + P) / P) + B3

At this time, since the offset in each spot occurs at the same ratio as the ratio of the amplitude of each difference signal, B1 / A1 = B2 / A2 = B3 / A3. Therefore, the multipliers G1 and G2 of the multipliers 59 and 57 are determined as in the following equations. G1 = A1 / (2 · A2) G2 = A2 / A3

By determining the multipliers G1 and G2 to values like the above equation, the tracking error signal TE becomes
The following equation is obtained, and a tracking error signal in which the offsets B1, B2, and B3 have disappeared is obtained. TE = TE1−G1 · (TE2 + G2 · TE3) = 2 · A1 · SIN (πX / P)

The DPP method is a modification of the push-pull method. The tracking error signal is detected by using the main beam and the two sub beams. However, since the land and the groove have the same track width, the tracking error signal is detected.
A three-beam method for detecting a tracking error signal using one beam cannot be adopted. This is because in the three-beam system, a tracking error signal is detected by detecting the difference in brightness between two sub-beams, but in this system, the values of the signals obtained from the two sub-beams are the same. This is because the difference in brightness between the two sub beams cannot be detected.

When the push-pull method is used, the ratio of the offset of the difference signal serving as the tracking error signal to the shift amount X of the objective lens (when a graph is drawn with the shift amount on the horizontal axis and the offset on the vertical axis) ) Becomes extremely large when compared with the three-beam method. Therefore, this offset becomes a problem when performing tracking control at the time of recording or reproduction, and it has been a problem to reduce this offset. However, by adopting the DPP method using the main beam and the two sub beams as in the present embodiment, the above-described processing is performed to remove the offset, and the tracking error signal does not include the offset. Is generated as Therefore, when performing tracking control,
Control is performed so that the objective lens follows the center position of the track.

The shift signal SFS sent from the output terminal of the operational amplifier 61 is represented by the offset B1 as shown in the following equation. Therefore, the shift signal SFS causes the main beam to be shifted from the light source optical axis by how much. Can be detected. SFS = TE1 + G1 · (TE2 + G2 · TE3) = 2B1

<Reproduction of Clock Mark> The reproduction operation of the clock mark will be described below. The clock mark is generated by the RF processing circuit 6 using the current signals d1, d2, e1, and e2 obtained from the photodiodes D1, D2, E1, and F1 (FIG. 7) of the second photodetector 50 (FIG. 7).
It is detected by performing (d1 + d2)-(e1 + f1) in (FIG. 1). The width of the clock mark in the track direction is smaller than the spot diameter of the main spot formed by the main beam. Therefore, when the main beam irradiates the clock mark, (d1 + d2)-(e1 +
When f1) crosses zero, it means that the main beam has passed the middle point of the clock mark.

The time from the detection of the midpoint of the clock mark to the detection of the midpoint of the next clock mark is determined by a clock having a period divided by a predetermined value (for example, 400). Generated by circuit 9 (FIG. 1). Using this clock and the above-described master clock, the digital PLL processing is performed in the digital servo processing circuit 10 (FIG. 1) as described above. Thus, the PLL
The processed signal is the PWM signal generation circuit 13 (FIG. 1)
After the PWM processing is performed, the signal subjected to the PWM processing is supplied to the spindle motor driver 15 (FIG. 1), whereby the rotation of the spindle motor 4 (FIG. 1) is controlled. The division value for generating the clock in the signal processing circuit 9 (FIG. 1) is T
The main information area 23 also exists in the OC area 22 (FIG. 2).
(FIG. 2) has the same value.

<Wobble Reproduction> A wobble reproduction operation will be described below. The wobble uses the current signals e1 and f1 obtained from the photodiodes E1 and F1 (FIG. 7) of the above-described second photodetector 50 (FIG. 7) to convert e1-f1 in the RF processing circuit 6 (FIG. 1). Detected by doing. Therefore, the wobble is detected by the difference signal TE1 used for detecting the tracking error signal.

That is, if the main beam supplied from the optical pickup 2 (FIG. 1) follows the center position of the track on the disk 1 (FIG. 1), the main beam irradiated by the main beam Diode E
A wobble exists in one of the portions detected by F1 and F1. Therefore, the photodiodes E1, F1
Have different values influenced by the wobble. Accordingly, the wobble is detected by obtaining the difference signal TE1. For data other than the data recorded by the wobble, the difference signal T
Since E1 is canceled when E1 is obtained, only a wobble signal which is data recorded by wobble is obtained.

<Main Loop of Tracking Servo> The main loop of the tracking servo will be described below with reference to the drawings. FIG. 8 is a block diagram showing the internal configuration of the digital servo processing circuit 10. As described above, since the tracking error signal is obtained by the RF processing circuit 6 (FIG. 1) using the DPP method, a tracking error signal having no offset can be obtained. This tracking error signal is digitized by the AD converter 7 (FIG. 1) and then sent to the digital servo processing circuit 10.

When the tracking error signal digitized by the AD converter 7 (FIG. 1) is sent to the digital servo processing circuit 10, it is first sent to the polarity inversion circuit 81. In the polarity inversion circuit 81, for example, when the signal of the track A (land) is reproduced,
When reproducing the (groove) signal, when the objective lens 44 (FIG. 5) is moved, the phase of the given tracking error signal is inverted so that the reproduced signal can be read. That is, in the polarity inversion circuit 81, when the track from which the given tracking error signal is read is different from the set track, the phase of the tracking error signal is inverted.

Then, the output signal of the polarity inversion circuit 81 is sent to the phase compensation circuit 82 and the sampling circuit 87. The phase compensation circuit 82 is a circuit provided for stabilizing the tracking servo system, and is configured by a filter. Such a phase compensation circuit 82 has, for example, a gain that is kept flat at about 60 db up to about 40 Hz, and a gain of about 40 Hz to 1 kHz.
It satisfies the open-loop characteristic that the gain drops at a rate of 12db / oct to the vicinity, and the gain drops at a rate of 6db / oct after about 1kHz.

When the output signal of the phase compensating circuit 82 has a large tracking error signal, the objective lens 44 emits the main beam to the center position of the track.
This is a negative feedback tracking drive signal to which a force for pulling back (FIG. 5) to face the center position of the track is applied. Then, this tracking drive signal is input to the gain switching circuit 83, and is amplified by a gain corresponding to recording and reproduction. Further, the gain is switched according to the track to be irradiated with the main beam.

The gain switching circuit 83 is connected to the contact c of the switch SW1. A reference voltage such as a ground voltage is applied to a contact point d of the switch SW1. By the switch SW1, the switch SW1 is connected to the contact d side to apply a reference voltage when recording or reproduction of the disk 1 (FIG. 1) is not performed while the power of the disk device is turned on. Objective lens 4
4 (FIG. 5) in the neutral position. Also, when performing a long search described later, the switch SW1 is connected to the contact d.
Connected to the side.

A switch SW is connected to the contact e of the switch SW1.
The second contact c and one end of the switch SW3 are connected. The power supply compensation circuit 85 is connected to the contact e of the switch SW2, and the hold circuit 84 is connected to the other end of the switch SW3. A switch S is connected to the output side of the hold circuit 84.
The contact d of W2 is connected. When supplied with the tracking drive signal, the power supply compensation circuit 85 compensates for the gain of the tracking drive signal with respect to a decrease in the voltage of the power supply unit (not shown) of the disk drive. The tracking drive signal compensated in this way is sent to an 8-bit digital signal generation circuit 86, converted into an 8-bit digital signal, and then sent to a PWM signal generation circuit 13, where a PWM process is performed. The signal is provided to the PWM driver 14 (FIG. 1) to drive the objective lens 44 (FIG. 5). . Further, the hold circuit 84 holds the instantaneous tracking drive signal.

As described above, the gain switching circuit 83, the hold circuit 84, and the power supply compensation circuit 85 are connected to the switches SW1 and SW1.
When performing recording or reproduction on the disk 1 (FIG. 1) when the connection is made by SW2 and SW3, the switches SW1 and SW2 are connected to the contact c side, and the contact of the switch SW3 is connected. Therefore, the tracking drive signal is supplied from the gain switching circuit 83 to the power supply compensation circuit 85 to close the main loop of the tracking servo, and the tracking drive signal is supplied to the hold circuit 84. The signal is held. However, the signal held by the hold circuit 84 is not given to the power supply compensation circuit 85 because the switch SW2 is connected to the contact c.

When a kick operation to be described later is performed, at the start of the kick operation, the switch SW2 is connected to the contact d, and the switch SW3 is turned off. As a result, the tracking drive signal immediately before starting the kick operation is supplied from the hold circuit 84 to the power supply compensation circuit 85 via the switch SW2. At this time, the main loop of the tracking servo is opened and the hold circuit 8
After the tracking drive signal held in 4 is given to the power supply compensation circuit 85 and corrected, the 8-bit digital signal generation circuit 86 converts the signal into an 8-bit digital signal.

Then, this 8-bit tracking drive signal is sent to the PWM signal generation circuit 13 and subjected to the PWM processing, and then given to the PWM driver 14 (FIG. 1).
The actuator of the objective lens 44 (FIG. 5) is driven. When the kick operation is completed, the switch SW2 is connected to the contact point c, the switch SW3 is turned on, and the tracking servo main loop is closed again.

On the other hand, the tracking error signal sent from the polarity inversion circuit 81 to the sampling circuit 87 is sampled, and the sampling result is given to the maximum amplitude detection means 88 and the drive pulse command circuit 90. The maximum amplitude detecting means 88 detects the maximum value of the amplitude of the tracking error signal from the given sampling result.
In the drive pulse command circuit 90, the objective lens 44 (FIG. 5)
An acceleration pulse or a deceleration pulse for accelerating or decelerating the moving speed of the motor is generated and sent to the power supply compensation circuit 85. Further, the first counter 91 detects the number of tracks crossed during the kick operation by detecting the number of times of switching of the count signal described later generated by the drive pulse command circuit 90.

Further, a threshold value of the level of the tracking error signal for determining the period of the driving pulse from the amplitude detected by the maximum amplitude detecting means 88 is generated by the threshold value generating circuit 89,
The generated threshold value is given to the drive pulse command circuit 90. A signal is supplied from the driving pulse command circuit 90 to the second counter 92, and the driving pulse generated by the driving pulse command circuit 90 is counted for a period, and the period is measured. The kick detection circuit 93 detects a kick operation from when the drive pulse command circuit 90 gives a drive pulse for accelerating the moving speed of the objective lens 44 (FIG. 5) until the tracking error signal crosses zero. When performing an odd number of kick operations, the polarity of the polarity inversion circuit 81 is inverted.

<Kick Operation> First, a kick operation for moving the objective lens 44 (FIG. 5) from the original track to the target track will be described with reference to FIGS. FIG.
Is a timing chart of each signal in the single kick operation. As described above, the tracking error signal is sampled by the sampling circuit 87.

Then, the maximum amplitude detecting means 88 always detects the maximum amplitude of the tracking error signal from the sampling data from the sampling circuit 87, and the maximum amplitude value is abnormally large during recording or reproduction. It is detected whether it is abnormally small. At this time, when an abnormal value is detected, the control microcomputer 8 (FIG. 1) recognizes that an abnormality has occurred in the tracking servo. For example,
The maximum amplitude value detected by the maximum amplitude detecting means 88 is 0.5 V ±
If it is out of the range of 0.1V, it will be judged as an abnormal value.

When the control microcomputer 8 (FIG. 1) recognizes that an abnormality has occurred in this way, the control microcomputer 8 (FIG. 1) uses the RF processing circuit 6 (FIG. 1) and the AD converter 7. (FIG. 1) and check whether the gain of each circuit constituting the digital servo processing circuit 10 is as set (for recording or reproduction, and for track A (land) or track B (groove)), and as set. If not, change the settings. At this time, if the setting is as set, the set value is changed, and if the set value indicates an abnormal value, recording or reproduction is stopped.

At the time of searching, the maximum amplitude detecting means 88
Detects the maximum amplitude value of the tracking error signal.
MAX shown in FIGS. 9 (a), 10 (a) and 11 (a)
Is the maximum amplitude value detected when a single kick operation is performed.

(1) Single kick operation First, a single kick operation that is a kick operation when the original track and the target track are adjacent to each other will be described. FIG. 9A shows the sampling waveform at this time. FIG.
(B) shows a drive signal applied to a drive coil provided in an actuator (not shown) for moving the objective lens 44 (FIG. 5). FIG. 9 (c) shows a first example for detecting how many tracks have been crossed during the kick operation.
3 shows a count signal applied to a counter 91. FIG. 9D shows a kick detection signal indicating that the kick operation generated by the kick detection circuit 93 is being performed.

First, when the control microcomputer 8 (FIG. 1) issues a single kick command, at the time A, the objective lens 44
An acceleration pulse is supplied from the drive pulse command circuit 90 to the power supply compensation circuit 85 so as to accelerate the moving speed shown in FIG. At this time, the switch SW2 is simultaneously connected to the contact d and the switch SW3 is turned off. Therefore, in the power supply compensation circuit 85, the acceleration pulse
After the signal on which the acceleration pulse is superimposed is superimposed on the tracking drive signal output from 4 and converted into an 8-bit digital signal by the 8-bit digital signal generation circuit 86,
The WM signal generation circuit 13 performs a PWM process.

The signal thus subjected to the PWM processing is applied to the PWM driver 14 (FIG. 1),
By the drive signal including the acceleration pulse as shown in (b),
The objective lens 44 (FIG. 5) is driven. At this time, the objective lens 44 (FIG. 5) performs an acceleration motion. At this time, if the friction and the viscosity are ignored, the motion becomes a constant acceleration motion. Therefore, the waveform of the sampling data between the time A and the time B in FIG. 9A is a waveform close to a parabola. The acceleration pulse given at this time is given, for example, as a square wave having a voltage amplitude value of about 250 mV.

At the same time, the kick detection circuit 93
The kick detection signal indicating that the kick operation has been started by detecting the generation of the acceleration pulse in the drive pulse command circuit 90 changes the kick detection signal to a low level (hereinafter, “L”) as shown in FIG. 9D. To high level (hereinafter, "H")
Switch). The kick detection signal is sent to the control microcomputer 8 (FIG. 1). Further, since one kick operation is performed, the number of tracks crossing the odd number is odd. Therefore, the kick detection signal is also supplied to the polarity inversion circuit 81, and the polarity is inverted.

The reason why a signal is supplied to the polarity inversion circuit 81 in advance and the polarity is inverted will be described. In the disk used in the present embodiment, tracks A (lands) and tracks B (grooves) are alternately formed. Therefore, for example, when the main spot of the main beam is located on the right side of the track A and when it is located on the right side of the track B, the direction of the force for pulling the main beam to the center position of the track is exactly opposite. This is also
The same applies when the main spot is located on the left side of each track. That is, it is necessary to reverse the phases of the tracking drive signals of the track A and the track B. Note that it is not necessary to perform such a phase inversion for a disk in which only lands or grooves are formed as tracks.

Therefore, when the kick operation is performed across an odd number of tracks, if the original track is track B (groove), the target track is track A (land). That is, if the number of tracks traversing at the time of the kick operation is an odd number, the state of the track changes and the phase is inverted. Conversely, if the number of traversing tracks is even, the state of the tracks is the same, so that the phase is not inverted. Therefore, when the number of crossing lines is an odd number and the main beam reaches the target track, it is necessary to invert the phase and switch the gain of each circuit. However,
When switching is performed after the main beam arrives, it takes time to pull in the servo accordingly. Therefore, as described above, by giving the kick detection signal to the polarity inversion circuit 81 and performing switching in advance, the time required for such pull-in can be reduced.

The kick detection signal is given to the control microcomputer 8 (FIG. 1) in order to make the control microcomputer 8 (FIG. 1) recognize that the kick operation is being performed. This is to prevent the control microcomputer 8 (FIG. 1) from issuing a new kick operation command. Furthermore, the control microcomputer 8 (FIG. 1) detects the generation of the acceleration pulse and the deceleration pulse described later to detect whether or not the kick operation is being performed.
It is more burdensome to recognize by giving this kick detection signal than in hardware.

In the threshold value generation circuit 89, a kick threshold value a which is a predetermined value (for example, a value of 1/2 of the maximum amplitude value) with respect to the maximum amplitude value detected by the maximum amplitude detection means 88 at the time of the previous kick operation is provided. Is generated and the drive pulse command circuit 9
Sent to 0. The reason why the maximum amplitude value in the previous kick operation is used to generate the kick threshold a will be described. When the maximum amplitude value is detected by the maximum amplitude detection means 88,
The detection timing is when the sampling data decreases by a predetermined amount from the maximum amplitude value. Therefore, when the kick threshold a, which is a predetermined value for the maximum value, is reached before the maximum value is detected, the acceleration pulse is stopped as described later, but the maximum amplitude value is not detected at this time. Therefore, the kick threshold a is determined using the maximum amplitude value detected during the previous kick operation.

As described above, the threshold value a for kick is generated by the threshold value generation circuit 89 based on the maximum amplitude value detected during the previous kick operation. However, when the kick operation is performed for the first time, the previous kick operation is performed. Since there is no data at the time of operation, the maximum amplitude value is obtained from the data obtained at the time of automatic adjustment, and this maximum amplitude value is used. This automatic adjustment means that, immediately after the disk 1 (FIG. 1) is mounted on the disk device, test-run each part of the disk device in order to determine the gain of each circuit for performing focus control and tracking control. It is to make it.

The drive pulse command circuit 90 given the kick threshold value a as described above constantly measures sampling data. When the sampling data reaches the kick threshold value a (time B), As shown in FIG. 9B, the generation of the acceleration pulse is stopped. The second counter 92 starts counting the number of times of sampling at time A when the drive pulse command circuit 90 generates the acceleration pulse, and stops the counting operation at time B when the generation of the acceleration pulse is stopped. The value obtained by multiplying the counted number by the sampling period is equal to the acceleration pulse application time T1, and this time T1 is stored in the control microcomputer 8 (FIG. 1) as the next deceleration pulse application time. Further, at this time B, as shown in FIG.
As a result, the count signal supplied to the first counter 91 switches from H to L.

After the application of the acceleration pulse is stopped as described above, the signal given to the PWM driver 14 (FIG. 1)
This is a signal generated only from the tracking drive signal sent from the hold circuit 84. This tracking drive signal is transmitted to the objective lens 44 (FIG. 5) immediately before the kick operation starts.
Because it is a signal for generating a force that holds the position of
There is no external force applied to the objective lens 44 (FIG. 5) other than the force generated by this signal. Therefore, the objective lens 44
(FIG. 5) shows the objective lens 44 immediately before the start of the kick operation in the direction in which the speed was accelerated when the acceleration pulse was received.
It moves without receiving an external force while maintaining the position of FIG. 5. Therefore, when friction and viscosity are ignored,
The objective lens 44 (FIG. 5) will start a constant velocity movement.

Thus, after time B, the objective lens 44
(FIG. 5) The maximum amplitude detecting means 8 is always in operation even while moving.
The sampling data is measured at 8 and its maximum amplitude value MAX (FIG. 9A) is detected, and this value is stored in the control microcomputer 8 (FIG. 1). The detected maximum amplitude value MAX is stored so that the threshold generation circuit 89 generates the kick threshold a when the next kick operation is performed.
Note that, theoretically, the maximum amplitude value is detected at a boundary position between the track A (land) and the track B (groove). At this time, the sampling data is also measured by the drive pulse command circuit 90, and at time C when the value becomes the kick threshold a again, the objective lens 44 (FIG. 5)
A deceleration pulse is generated to reduce the moving speed of the robot.

The deceleration pulse is supplied to the drive pulse command circuit 9
0 to the power supply compensation circuit 85 and the hold circuit 8
4 is superimposed on the tracking drive signal given by the reference numeral 4.
After the tracking drive signal on which the deceleration pulse is superimposed as described above is converted into an 8-bit digital signal by the 8-bit digital signal generation circuit 86, the PWM signal is generated by the PWM signal generation circuit.
It is processed and sent to the PWM driver 14 (FIG. 1). 9 by the PWM driver 14 (FIG. 1).
A drive signal as shown in FIG.
When the moving speed of (FIG. 5) is controlled to be reduced, the objective lens 44 (FIG. 5) receives an external force in a direction opposite to that when the acceleration pulse is given, and is decelerated.

When the acceleration pulse application time T1 stored in the control microcomputer 8 (FIG. 1) has elapsed after the generation of the deceleration pulse from the drive pulse command circuit 90, the application of the deceleration pulse is stopped. At this time, if the deceleration pulse application time is T2, T2 = T1. However, when the sampling data crosses zero before the time T1 has elapsed, the application of the deceleration pulse is stopped at that moment. Therefore, at this time, T2 <T1. As described above, the time when the time T1 has elapsed since the generation of the deceleration pulse or the time when the sampling data has zero-crossed after the generation of the deceleration pulse, whichever is earlier, is the time when the application of the deceleration pulse is stopped. D.

As described above, the application of the deceleration pulse is stopped, the switch SW2 is connected to the contact point c, and the switch SW3 is turned on, so that the main loop of the tracking servo is closed. At this time, in the gain switching circuit 83, the gain is raised and the pull-in is performed. When this pull-in is completed, the gain given by the gain switching circuit 83 is returned to the normal gain set for recording or reproduction, and tracking is performed. At this time, as described above, since the kick detection signal is given so that the phase of the tracking drive signal is inverted by the polarity inversion circuit 81, normal tracking servo control is performed. The gain of the gain switching circuit 83 is also switched to a predetermined gain corresponding to the target track.

At this time, the kick detection signal switches from H to L due to the start of the servo pull-in, and the control microcomputer 8 (FIG. 1) recognizes the end of the kick operation. By recognizing in this way, the control microcomputer 8 (FIG. 1) gives a command to the drive pulse command circuit 90 to perform the kick operation again if the track being tracked at the end is not the target track. It becomes possible.

When the kick detection signal ends, the count signal supplied from the drive pulse command circuit 90 to the first counter 91 switches from L to H and returns to the original state, and how many times the count signal switches. The first counter 91 counts the difference and gives the count result to the control microcomputer 8 (FIG. 1). The control microcomputer 8 (FIG. 1) to which the count result is given in this manner determines whether or not a predetermined kick operation has been performed. In the case of FIG. 9, since the count signal is switched only once,
It is determined that the single kick operation has been performed normally.

(2) Two to Four Kick Operation The two to four kick operation will be described by taking a two kick operation as an example. Note that the 2 to 4 kick operation is basically the same as the single kick operation in the progress of the operation. FIG. 10 shows a timing chart during the double kick operation. FIG. 10A shows a sampling waveform at this time. FIG. 10B shows the objective lens 44.
Actuator (not shown) for moving (FIG. 5)
2 shows a drive signal to be provided to a drive coil provided in the inside.
FIG. 10C shows a count signal provided to the first counter 91 to detect how many tracks have been crossed during the kick operation. FIG. 10D shows a kick detection signal indicating that the kick operation generated by the kick detection circuit 93 is being performed.

First, similarly to the single kick operation, a command for two kicks is given from the microcomputer 8 for control (FIG. 1), and the acceleration pulse is supplied from the drive pulse command circuit 90 to the power supply compensation circuit 8.
5 (time A). At this time, at the same time, the switch SW2 is connected to the contact
3 becomes OFF. Therefore, the acceleration pulse is superimposed on the tracking drive signal output from the hold circuit 84 in the power supply compensation circuit 85, and the signal on which the acceleration pulse is superimposed is converted into an 8-bit digital signal by the 8-bit digital signal generation circuit 86. Then, the PWM signal is generated by the PWM signal generation circuit 13.
It is processed.

The signal thus subjected to the PWM processing is applied to the PWM driver 14 (FIG. 1),
By the drive signal including the acceleration pulse as shown in (b),
The objective lens 44 (FIG. 5) is driven. At this time, the objective lens 44 (FIG. 5) performs an acceleration motion.

At this time, the kick detection circuit 93
The kick detection signal indicating that the kick operation has been started by detecting the generation of the acceleration pulse in the drive pulse command circuit 90 is changed from L to H as shown in FIG.
Switch to. This kick detection signal is sent to the control microcomputer 8 (FIG. 1). Further, since two kick operations are performed, the number of tracks crossing the even number is even. Therefore, the kick detection signal is not supplied to the polarity inversion circuit 81, and the polarity is not inverted.

After the generation of the acceleration pulse, the drive pulse command circuit 90 measures the sampling data, and the kick threshold a given by the threshold generation circuit 89 is obtained.
(Time B), the generation of the acceleration pulse is stopped as shown in FIG. In addition, between the time A and the time B, the second counter 92 counts the number of samplings, obtains the acceleration pulse application time T1 from the counted number, and stores it in the control microcomputer 8 (FIG. 1). Further, at this time B, as shown in FIG. 10C, the count signal given to the first counter 91 from the drive pulse command circuit 90 switches from H to L.

When the application of the acceleration pulse is stopped as described above, the objective lens 44 (FIG. 5) immediately before the kick operation starts is moved in the direction in which the speed was accelerated when the acceleration pulse was received. While maintaining the position of (1), it moves at a constant speed without receiving external force. Thus, time B
Thereafter, even while the objective lens 44 (FIG. 5) is moving, the sampling data is always measured by the maximum amplitude detecting means 88, and the maximum amplitude value MAX1 (FIG. 10A) is detected. It is stored in the control microcomputer 8 (FIG. 1).

As described above, when the maximum amplitude value MAX1 is detected, the sampling data crosses zero as shown in FIG. Now, as shown in FIG. 10A, when the maximum amplitude value MAX1 is detected as a positive value, the sampling data becomes a negative value after zero-crossing. Conversely, when the maximum amplitude value MAX2 is detected as a negative value, the sampling data becomes a positive value after zero-crossing.

In this way, in FIG. 10A, when the sampling data becomes a negative value, the driving pulse command circuit 90 measures the sampling data and becomes the kick threshold value b given by the threshold value generation circuit 89. Sampling data is detected. This kick threshold b is
Similarly to the kick threshold a, a predetermined value corresponding to the negative maximum amplitude value measured by the maximum amplitude detecting means 88 when the previous kick operation was performed and stored in the control microcomputer 8 (FIG. 1). (For example, 1/2 of the maximum amplitude value)
, And is generated in the threshold value generation circuit 89.

After the maximum amplitude value MAX2 on the negative side is detected by the maximum amplitude detecting means 88 as shown in FIG. 10A, the sampling data having the same value as the kick threshold value b is again supplied to the drive pulse command. The signal is detected by the circuit 90. As described above, at time C when the sampling data having the same value as the kick threshold value b is detected for the second time, the drive pulse command circuit 90 generates a deceleration pulse.

The deceleration pulse is supplied to the drive pulse command circuit 9
0 to the power supply compensation circuit 85 and the hold circuit 8
4 is superimposed on the tracking drive signal given by the reference numeral 4.
After the tracking drive signal on which the deceleration pulse is superimposed as described above is converted into an 8-bit digital signal by the 8-bit digital signal generation circuit 86, the PWM signal is generated by the PWM signal generation circuit.
It is processed and sent to the PWM driver 14 (FIG. 1). 1 by the PWM driver 14 (FIG. 1).
0 (b) is given and the objective lens 4
4 (FIG. 5) is controlled so that the moving speed decreases.
The objective lens 44 (FIG. 5) receives an external force in a direction opposite to that when the acceleration pulse is given, and decelerates. At this time,
In the drive pulse command circuit 90, the count signal is switched from L to H as shown in FIG.

After the deceleration pulse is generated from the drive pulse command circuit 90, the time T1 has elapsed since the generation of the deceleration pulse, or the time when the sampling data crossed zero after the generation of the deceleration pulse. At the earlier time D, the application of the deceleration pulse from the drive pulse command circuit 90 is stopped. As described above, the application of the deceleration pulse is stopped, the switch SW2 is connected to the contact c, and the switch SW3 is turned on, so that the main loop of the tracking servo is closed. At this time, in the gain switching circuit 83, the gain is raised and the pull-in is performed for a predetermined time.

At this time, the kick detection signal switches from H to L due to the start of the servo pull-in, and the control microcomputer 8 (FIG. 1) recognizes the end of the kick operation. With the end of the kick detection signal, the count signal given to the first counter 91 from the drive pulse command circuit 90 is returned to the original state, and the first counter 91 counts how many times the count signal has been switched. The count result is given to the control microcomputer 8 (FIG. 1).
The control microcomputer 8 to which the count result is given as described above.
In FIG. 1, it is determined whether or not a predetermined kick operation has been performed. In the case of FIG. 10, since the count signal has been switched twice, it is determined that the two kick operation has been performed normally.

When the pull-in is completed, the gain given by the gain switching circuit 83 is returned to the usual gain for recording or reproduction, and tracking is performed. Although the example in which the sampling data first shifts to the positive side has been described with reference to FIG. The application of the pulse is stopped, and the application of the deceleration pulse is started when the kick threshold a is detected.

In the three kick operation, similarly to the single kick operation, first, at the same time as the kick operation starts, the main loop of the tracking servo is opened and a kick detection signal is given to the polarity inversion circuit 81 to invert the polarity. I do. Then, an acceleration pulse is given from the start of the kick operation until the sampling data reaches the kick threshold a (kick threshold b).

Next, after the sampling data has zero-crossed twice and the maximum value on the positive side (negative side) is detected, the kick threshold a (kick threshold b) is detected again from the time when the kick threshold a is detected again.
The deceleration pulse is applied until the time when the application time of the acceleration pulse has elapsed from this time or the time when the sampling data crosses zero after the generation of the deceleration pulse, whichever is earlier. Then, the main loop of the tracking servo is closed, and the gain given by the gain switching circuit 83 is increased to perform the pull-in.

Further, the count signal is a kick threshold a
When the application of the acceleration pulse at which the (kick threshold b) is detected is stopped, the switch is made from H to L, and after the zero crossing of the sampling data, the second kick threshold b (kick threshold a) is detected. Sometimes switches from L to H. Then, when the kick threshold a (kick threshold b) is detected for the first time after the sampling data crosses zero again, the count signal changes from H to L. Then, the application of the deceleration pulse is stopped to start the pull-in, and the count signal is returned to the original H state. At this time, the first counter 91 confirms that the value of the count signal has changed three times. As for the four kick operation, the same operation as the above-described two kick operation and three kick operation is performed, and the description thereof will be omitted.

As described above, when performing the kick operation of one to four kicks, the moving speed is increased to move the objective lens 44 (FIG. 5), and the moving speed is reduced to stop at the target track. In between, there is provided a period of moving at a constant speed. Therefore, when a deceleration pulse is given immediately after an acceleration pulse is given to a drive signal for driving the objective lens 44 (FIG. 5), a sudden impact applied to the objective lens 44 (FIG. 5) can be reduced.

Further, since no external force other than the force for holding the objective lens 44 (FIG. 5) before the start of the kick operation is applied to the objective lens 44 (FIG. 5), the motion is almost equal to the constant velocity motion. Operation. Therefore, sampling data of the tracking error signal is obtained as sinusoidal data. As a result, the values of the kick thresholds a and b can be more accurately grasped, so that the application stop time of the acceleration pulse and the start time of the application of the deceleration pulse can be accurately executed as set.

Further, in this embodiment, a predetermined value for the maximum amplitude of the tracking error signal is set as the kick threshold,
The acceleration pulse is stopped by the kick threshold. Therefore, even if the amplitude of the tracking error signal varies due to the variation in the detection characteristics of the light receiving element, the acceleration pulse application time is substantially constant. Similarly, the start of application of the deceleration pulse is also performed by a kick threshold which is a predetermined value with respect to the maximum amplitude of the tracking error signal. Therefore, the constant-velocity movement period during which the objective lens 44 (FIG. 5) moves at a constant speed becomes substantially constant.

As described above, since the acceleration pulse application time, the constant velocity motion period, and the deceleration pulse application time are almost constant, the objective lens 44 (FIG. 5) for one kick operation for each of one to four kick operations is used. The amount of movement in ()) is substantially constant without being affected by the detection characteristics of the light receiving element.

Further, since the application of the acceleration pulse is stopped at the kick threshold value which becomes a predetermined value with respect to the maximum amplitude of the tracking error signal, in each of the 1 to 4 kick operations, the acceleration with respect to the movement amount per one kick operation is performed. The ratio of the amount of movement during the period in which the pulse is applied is substantially constant without being affected by the variation in the response characteristics of the actuator. Therefore, variations in the detection characteristics of the light receiving element and the response characteristics of the actuator can be absorbed.

As described above, since variations in the detection characteristics of the light receiving element and the response characteristics of the actuator can be absorbed, the accuracy of the acceleration pulse and the deceleration pulse is increased. Therefore, by increasing the amplitude levels of the acceleration pulse and the deceleration pulse, the acceleration applied to the objective lens 44 (FIG. 5) in the kick operation can be increased, and the time spent in the kick operation can be reduced.

(3) 5-10 kick operation The 5-10 kick operation will be described. In addition, this 5
Basically, in the kick operation of 10 to 10 kicks, in the progress of the kick operation and the operation of 1 to 4 kicks, after the acceleration pulse is given, the objective lens 44 (FIG. 5) is moved at a constant speed for a certain period,
It is the same in that a deceleration pulse is given. However, since the amount of movement of the objective lens 44 (FIG. 5) increases, it is necessary to lengthen the period during which the acceleration pulse and the deceleration pulse are applied.

FIG. 11 is a timing chart for the six kick operation. FIG. 11A shows a sampling waveform at this time. FIG. 11B shows the objective lens 4.
4 shows a drive signal applied to a drive coil provided in an actuator (not shown) for moving the actuator 4 (FIG. 5). FIG. 11C shows a count signal supplied to the first counter 91 to detect how many tracks have been crossed during the kick operation. FIG. 11D shows a kick detection signal indicating that the kick operation generated by the kick detection circuit 93 is being performed. Hereinafter, the kick operation will be described with reference to FIG. 11, and the six kick operations will be described corresponding to the n kick operations.

First, in the same manner as the 1-4 kick operation, a command for n (6) kicks is given from the control microcomputer 8 (FIG. 1). (Time A). At this time, the switch SW2 is simultaneously connected to the contact d and the switch SW3 is turned off. Therefore, the power supply compensation circuit 8
In 5, the acceleration pulse is superimposed on the tracking drive signal output from the hold circuit 84. The signal on which the acceleration pulse is superimposed is converted into an 8-bit digital signal by the 8-bit digital signal generation circuit 86, and then the PWM signal is generated. Circuit 1
In step 3, PWM processing is performed.

The signal thus subjected to the PWM processing is applied to the PWM driver 14 (FIG. 1),
By the drive signal including the acceleration pulse as shown in (b),
The objective lens 44 (FIG. 5) is driven. At this time, the objective lens 44 (FIG. 5) performs an acceleration motion.

At this time, the kick detection circuit 93
The kick detection signal indicating that the kick operation has been started by detecting the generation of the acceleration pulse in the drive pulse command circuit 90 is changed from L to H as shown in FIG.
Switch to. This kick detection signal is sent to the control microcomputer 8 (FIG. 1). Further, when the n kick operation crosses an odd number of tracks, this kick detection signal is supplied to the polarity inversion circuit 81, and the polarity is inverted. In addition, as shown in FIG.
When the track crosses the track (book), the kick detection signal is not supplied to the polarity inversion circuit 81, and the polarity is not inverted.

After the generation of the acceleration pulse, the drive pulse command circuit 90 measures the sampling data and determines the kick threshold a given by the threshold generation circuit 89.
Reach At this time, the application of the acceleration pulse is not stopped as in the kick operation of 1 to 4 kicks, but the count signal is switched from H to L in the drive pulse command circuit 90 as shown in FIG. Then, as shown in FIG. 11A, the first maximum amplitude value on the positive side is detected by the maximum amplitude detection means 88. The maximum amplitude value on the positive side is the data at the time of the next kick operation. Do not use as

Thereafter, when the drive pulse command circuit 90 again detects the sampling data serving as the kick threshold value a (time B), the generation of the acceleration pulse is stopped as shown in FIG. 11B. The time T1 during which the acceleration pulse is applied in this manner is set to the second
Calculated by counting the number of times of sampling by the counter 92, the time 2 / 3T1 is stored in the control microcomputer 8 (FIG. 1). The reason why the acceleration pulse application time is multiplied by 2/3 is to make the deceleration pulse time slightly shorter than the acceleration pulse time.

By stopping the application of the acceleration pulse in this manner, the objective lens 44 (FIG. 5) shifts from the acceleration motion to the constant velocity motion. At this time, since the acceleration pulse application time is given longer than the acceleration pulse application time in the 1 to 4 kick operation, the moving speed of the objective lens 44 (FIG. 5) is faster than the moving speed in the 1 to 4 kick operation. Then, after the application of the acceleration pulse is stopped, FIG.
The sampling data of (a) crosses zero, and the driving pulse command circuit 90 detects the sampling data which becomes the kick threshold value b given by the threshold value generation circuit 89. At this time, as shown in FIG.
At 0, the count signal is switched from L to H.

Thereafter, as shown in FIG. 11A, the maximum amplitude value on the negative side is detected by the maximum amplitude detection means 88, and this maximum amplitude value is stored in the control microcomputer 8 (FIG. 1). This is because the objective lens 44 (FIG. 5) is moving at a constant speed. Further, as shown in FIG. 11A, the sampling data which becomes the kick threshold value b is detected again by the drive pulse command circuit 90, but at this time, the count signal is not switched. As described above, the count signal is switched from H to L when the kick threshold a is detected for the odd number of times, and when the kick threshold b is detected for the odd number,
Switch from L to H. Therefore, hereinafter, the switching of the count signal is omitted.

As shown in FIG. 11A, after the second maximum amplitude value on the positive side is detected by the maximum amplitude detection means 88, the sampling data crosses zero, and the second maximum value on the negative side is detected. The amplitude value is detected by the maximum amplitude detecting means 88. At this time, the second maximum amplitude value on the positive side is stored in the control microcomputer 8 (FIG. 1), and is deleted from the storage of the first maximum amplitude value on the negative side. The negative maximum amplitude value is stored in the control microcomputer 8 (FIG. 1). At this time, the maximum amplitude value on the negative side to be stored is 2
The reason for adopting the maximum negative amplitude value on the negative side is that data more stable than that detected on the first time is obtained.

That is, in order to increase the accuracy of the maximum amplitude value to be stored, data measured at a low speed point is better than the relationship with the sampling frequency for obtaining the sampling data. Therefore, since the maximum amplitude value obtained at a location where the speed is slightly reduced due to friction or the like is obtained as more stable data than immediately after the acceleration motion is stopped, the data is controlled as the maximum amplitude value. In the microcomputer 8 (FIG. 1).

As described above, while the deceleration pulse is applied and the objective lens 44 (FIG. 5) is moving at a constant speed, the maximum amplitude values on the positive and negative sides are respectively detected a plurality of times.
Of these, the most stable data is selected and stored in the control microcomputer 8 (FIG. 1) as the maximum amplitude value on the positive and negative sides. Further, as described above, the count signal is switched a plurality of times, and after it is confirmed by the first counter 91 that the count signal has been switched n-1 (5) times, the maximum amplitude value is then changed by the maximum amplitude detection means 88. Is detected. At time C near the time when the maximum amplitude value is detected, the drive pulse command circuit 90 generates a deceleration pulse. The maximum amplitude value detected in the vicinity of time C is the maximum amplitude value on the positive side when the n kick operation is an even kick operation, and is negative when the odd kick operation is an odd kick operation. Is the maximum amplitude value.

As described above, the trigger for starting the application of the deceleration pulse is the one having the fastest time among the following three. 1. When the sampling count reaches a certain set count. 2. When the sampling data reaches a predetermined value (for example, 98%) of the maximum amplitude value stored in the control microcomputer 8 (FIG. 1) on the same polarity side as the maximum amplitude value detected near time C. 3. When the maximum amplitude value is detected at the (n-1) (5th) time (this number is the number of times the maximum amplitude value is detected regardless of the sign).

[0179] 1. Is based on the number of times of sampling as described above, the amount of movement of the objective lens 44 (FIG. 5) from time B to time C is determined from the predetermined position of the track adjacent to the original track to the distance between the track adjacent to the target track. This is because it is up to a position near the boundary with the track further adjacent to this track. That is, while the amount of movement of the objective lens 44 (FIG. 5) from time B to time C is a known value,
Since the objective lens 44 (FIG. 5) moves at a constant speed, the time from time B to time C can be determined by detecting the speed. Therefore, when this time is divided by the sampling time, the set number of times of sampling is obtained.

2. When the maximum amplitude value stored as described above is used as a reference, the maximum amplitude value serving as the reference is already stored in the control microcomputer 8 (FIG. 1) when the n kick operations are even kick operations. The maximum amplitude value on the positive side, and when the kick operation is an odd number of kick operations, the maximum amplitude value on the negative side already stored in the control microcomputer 8 (FIG. 1). Also, 3. The reason why the deceleration pulse is generated based on the maximum amplitude value detected at the (n-1) -th time as described above is that the maximum amplitude value detected at this time is already stored in the same polarity as the maximum amplitude value. This is when the value is smaller than the maximum amplitude value and the moving speed of the objective lens 44 (FIG. 5) is high. In addition, 2. 2. the stored maximum amplitude value, or N-1
(5) When the deceleration pulse is generated with reference to the maximum amplitude value detected the third time, the application time of the deceleration pulse or its amplitude level may be corrected.

As described above, the application of the deceleration pulse starts at time C, and after the lapse of time T2 (= ２T1), the application of the deceleration pulse is stopped (time D). The reason why the application time of the deceleration pulse is shorter than the application time of the acceleration pulse is that the moving direction of the objective lens 44 (FIG. 5) after stopping the application of the deceleration pulse is the same as the moving direction by the acceleration pulse (to the target track). (Moving direction). That is, by applying a deceleration pulse, the moving direction of the objective lens 44 is prevented from being reversed (the direction to move to the original track).

After the application of the deceleration pulse is stopped, in the 1 to 4 kick operation, the switches SW2 and SW3 are switched to close the main loop of the tracking servo, and the pull-in operation is started. However, in the n (6) kick operations, the switches SW2 and SW3 are not switched. In other words, with the tracking servo main loop open,
No pull-in operation is performed.

Therefore, the objective lens 44 (FIG. 5) moves at a constant speed toward the target track at the speed reduced by the deceleration pulse. At this time, the moving speed of the objective lens 44 (FIG. 5) is a speed that can be sufficiently pulled in by the tracking servo. The reason why the main loop of the tracking servo is kept open after the application of the deceleration pulse is that the decelerated moving speed of the objective lens 44 (FIG. 5) is reduced by closing the main loop of the tracking servo. This is to prevent acceleration due to the generated drive signal.

As described above, after the deceleration pulse is given,
While the objective lens 44 is moving at a constant speed, the kick threshold is detected again by the drive pulse command circuit 90, the count signal is switched, and the sampling data crosses zero as shown in FIG. When the drive pulse command circuit 90 detects the sampling data in the vicinity of the zero crossing point of the sampling data, the switch SW2 is connected to the contact c and the switch SW2 is connected.
3 turns ON, and the main loop of the tracking servo is closed.

At this time, the gain given by the gain switching circuit 83 is increased to start the pull-in operation, the pull-in of the objective lens 44 (FIG. 5) to the target track starts, and the kick detection circuit 93 outputs the kick detection signal. Is switched from H to L to make the control microcomputer 8 (FIG. 1) recognize that the kick operation has ended. Then, when the pull-in is completed, the gain given by the gain switching circuit 83 is returned to the usual gain for recording or reproduction, and tracking is performed.

Although the example in which the sampling data first shifts to the positive side has been described with reference to FIG. 11, when the sampling data first shifts to the negative side, the second kick threshold value b becomes When detected, the application of the acceleration pulse is stopped. The application of the deceleration pulse starts near the maximum amplitude value detected at the (n-1) th time.

According to such an n-kick operation, the objective lens 44 (FIG. 5) is decelerated at a track several tracks before reaching the target track, and moves at a constant speed at a speed at which the target track is sufficiently retracted. To approach the destination track. Then, when the objective lens 44 (FIG. 5) reaches near the center position of the target track, the pull-in by the tracking servo is performed, so that the target track can be reliably reached. Therefore, as before,
Optical pickup 2 generated when kick operation is performed
(FIG. 1) An anti-slip circuit provided to prevent runaway from occurring is not required. Further, since the target track is reliably reached, it is not necessary to perform the kick operation again. Therefore, the time for searching for the target track is reduced.

If an accurate kick operation cannot be performed and the target track cannot be detected even after a lapse of a predetermined time from the start of the kick operation, the tracking servo circuit is temporarily shut off and then turned on again. By state
Optical pickup 2 by instantly pulling into truck
(FIG. 1) Runaway can be prevented.

(4) Another Example of Single Kick Operation Another example of single kick operation will be described below.
This single kick operation is schematically described in FIG.
The application time T1 of the acceleration pulse shown in (b) is shortened, and the application time T2 of the deceleration pulse is set to zero.

First, when the control microcomputer 8 (FIG. 1) issues a single kick command, an acceleration pulse is supplied from the drive pulse command circuit 90 to the power supply compensation circuit so as to accelerate the moving speed of the objective lens 44 (FIG. 5). 85. At this time, at the same time, the switch SW2 is connected to the contact d side and the switch SW3 is turned off to open the main loop of the tracking servo, and the hold circuit 8
4 so that the tracking drive signal is sent to the power supply compensation circuit 85.

In the threshold value generation circuit 89, a kick threshold value a which is a predetermined value (for example, a value of 1/10 of the maximum amplitude value) with respect to the maximum amplitude value detected by the maximum amplitude detection means 88 at the time of the previous kick operation. Is generated and sent to the drive pulse command circuit 90. The kick threshold a is
It is smaller than the kick threshold a described in (1). When the drive pulse command circuit 90 detects the sampling data that becomes the kick threshold value a, the application of the acceleration pulse is stopped, the switch SW2 is connected to the c side, and the switch SW3 is turned on to turn on the tracking servo. Close the main loop.

By doing so, the pull-in operation of the objective lens 44 (FIG. 5) is started, and the pull-in to the original track is about to be performed. Since the moving speed is accelerated toward the target track, it can cross the boundary with the next target track although it is decelerated. Therefore, the objective lens 44 thus moved to the target track
(FIG. 5) is moved to the center position of the target track by the pull-in operation of the target track because the moving speed of the target track is reduced before the boundary with the original track is crossed.

As described above, the application time is shortened in order to reduce the energy of the acceleration pulse. However, a single kick operation in which the deceleration pulse is set to 0 by reducing the applied voltage may be performed. After giving the acceleration pulse,
After the objective lens 44 (FIG. 5) is moved at a constant speed until the objective lens 44 (FIG. 5) reaches the vicinity of the boundary between the original track and the target track (the sampling data has the maximum amplitude value), the tracking servo Close the loop,
The pull-in operation may be started.

<Tracking Servo Sub-Loop> The tracking servo sub-loop will be described with reference to the drawings. FIG. 12 is a block diagram showing a partial configuration of a tracking servo sub-loop. FIG. 13 is a block diagram showing the internal configuration of the speed / movement distance calculation circuit 12. FIG. 14 is a timing chart of each signal generated when the rotation speed of the sled motor 5 is detected. FIG. 15 is a diagram showing a positional relationship between the objective lens 44, the disk 1, and the light source.

As described above, the tracking error signal TE and the shift signal SFS are generated by the RF processing circuit 6 (FIG. 1) from the reflected light of the main beam and the sub beam received by the optical pickup 2 (FIG. 1). As shown in FIG. 12, the tracking error signal TE or the shift signal S
After being digitized by the AD converter 7 (FIG. 1), the FS is input to the positive-phase input terminal a of the operational amplifier 94 in the digital servo processing circuit 10 via the switch SW4. The tracking error signal TE or the shift signal SFS is input to the contact c of the switch SW4, the thread motor drive signal SD described later is input to the contact d of the switch SW4, and the contact e of the switch SW4 is connected to the negative-phase input terminal a of the operational amplifier 94. While being connected, the switch SW4 is now connected to the contact c side. Further, a speed signal E output from a speed / movement distance calculation circuit 12 described later is input to the opposite-phase input terminal b of the operational amplifier 94.

The operational amplifier 94 outputs a difference signal e between the tracking error signal TE or the shift signal SFS and the speed signal E, and the difference signal e is amplified by the amplifier 95 and output as the drive signal e0. This drive signal e
0 is input to the PWM signal generation circuit 13, subjected to PWM processing, and provided to the PWM driver 14. The PWM driver 14 controls the rotation of the thread motor 5 based on the PWM-processed drive signal, and the Hall elements 11a and 11b output signals P1 and P2 in accordance with the rotation of the thread motor. .Movement distance calculation circuit 12
Given to. As described above, when tracking control is performed by the main loop, the sled motor 5 is controlled by such a sub-loop.

The signal P shown in FIGS.
When P1 and P2 are input to the speed / movement distance calculation circuit 12 from the Hall elements 11a and 11b, respectively, the signal P1 is converted into a differentiation circuit 101 and a comparator 103 as shown in FIG.
, The signal P2 is supplied to the differentiating circuit 102 and the comparator 104. In addition, in the signals P1 and P2, FIG.
(B) As is clear, the phase of the signal P2 is advanced by π / 2 with respect to the signal P1. Therefore, the Hall element 1
NS that rotate 1a and 11b in synchronization with an output shaft (not shown) of the sled motor 5 are arranged to face rotating plates (not shown) alternately magnetized at equal intervals. That is, for example, N
Hall element 11a at the boundary between pole block and south pole block
Is arranged, the Hall element 11b is arranged at the center position of the N pole block.

Signals P1 and P2 are output from Hall elements 11a and 11a.
4 shows a positional relationship between the magnetic element b and a magnetized portion (not shown) of the thread motor 5 which is to face the Hall elements 11a and 11b. Further, since the signals P1 and P2 are arranged so as to be out of phase by 90 ° with respect to the magnetic pole of the magnetized portion, the signals P1 and P2 have a sinusoidal shape as shown in FIGS. The waveform has a 90 ° phase shift. Such signals P1 and P2 are differentiated by differentiating circuits 101 and 102, respectively, to generate differentiated signals Q1 and Q2. The differential signals Q1 and Q2 are shifted by -90 ° in phase as compared with the signals P1 and P2 having waveforms as shown in FIGS. 14 (a) and 14 (b), as shown in FIGS. 14 (c) and 14 (d). Waveform.

In the comparators 103 and 104, the signal P
1 and P2 are respectively compared with the values at the center of the waveforms of FIGS. That is, assuming that the value of the center of the waveforms of FIGS. 14A and 14B is 0, the positive signals of the position signals P1 and P2 are sent to the square wave generation circuits 105 and 106. In the square wave generation circuits 105 and 106, the square wave signals R1 and R as shown in FIGS. 14 (e) and (f) are obtained from the positive signals of the position signals P1 and P2 given thereto.
Generate 2. The square wave signals R1 and R2 are signals obtained by binarizing the signals P1 and P2 with the center of the waveform as a boundary.

The differentiated signals Q1 and Q2 generated by the differentiating circuits 101 and 102 are respectively
7, 108, and a square wave generation circuit 105, 1
The square wave signals R1 and R2 generated at 06 are respectively
It is provided to inverting circuits 108 and 107. Inverting circuit 107
Is output by inverting the differential signal Q1 when the square wave signal R2 is at a high level (hereinafter, referred to as “H”), and outputting the differential signal when the square wave signal R2 is at a low level (hereinafter, referred to as “L”). Q1 is output as it is. The inverting circuit 108 outputs the differential signal Q2 as it is when the square wave signal R1 is H, and inverts and outputs the differential signal Q2 when the square wave signal R1 is L.

In the case of FIG. 14, when the square wave signal R2 is H, the differential signal Q1 becomes a negative value, and the square wave signal R
When 2 is L, the differential signal Q1 has a positive value. When the square wave signal R1 is H, the differential signal Q2 has a positive value,
When the square wave signal R1 is L, the differential signal Q2 has a negative value. Therefore, the signal S1 output from the inversion circuit 107
Is a signal obtained by inverting the differential signal Q1 when the square wave signal R2 is H, and the signal S2 output from the inverting circuit 108 is differentiating the differential signal Q1 when the square wave signal R1 is L.
2 is an inverted signal. Therefore, the signals S1 and S2
Are as shown in FIGS. 14 (g) and (h), and always have a positive value. The traveling direction of the optical pickup 2 (FIG. 1) is determined by signals P1 and P2 given by the Hall elements 11a and 11b.
14A and 14B, the signals S1 and S2 have negative values.

The signals S1 and S2 are added to the adder 10
9, the signal is added as shown in FIG. 14 (i), and becomes a signal substantially proportional to the rotation speed of the sled motor 5. The signal S1 + S2 to which the signals S1 and S2 are added removes switching noise by the smoothing circuit 110, so that a smoothed speed signal E is generated. The speed signal E generated by the smoothing circuit 110 is output to the operational amplifier 9.
4 is input to the negative-phase input terminal b.

The speed signal E obtained at this time is neither absolute rotation speed of the sled motor 5 nor completely proportional to the absolute rotation speed of the sled motor 5, but is substantially approximately proportional to the absolute rotation speed. You can think that you are doing. In the present embodiment, the speed control based on a two-phase position signal using two Hall elements has been described. However, by using a plurality of Hall elements and making the position signal multi-phase, the speed signal E becomes the absolute value of the thread motor. Approaches a value that is directly proportional to the typical rotation speed. In addition, such speed detection can be used in a tracking servo sub-loop since the instantaneous speed can be detected. The operation of the tracking servo sub-loop will be described below.

(1) When Using Tracking Error Signal TE First, the operation of the sub-loop when the signal input to the positive-phase input terminal a of the operational amplifier 94 is the tracking error signal TE will be described. The difference signal e is a difference signal between the speed signal E output from the speed / movement distance calculation circuit 12 and the tracking error signal TE, and the relationship is expressed by the following equation. e = TE-E

The difference signal e output from the operational amplifier 94 is amplified A times by the amplifier 95, so that the output signal e0 of the amplifier 95 is expressed by the following equation. e0 = A.e = A. (TE-E)

The output signal e0 of the amplifier 95 is PWM
After being subjected to the PWM processing by the signal generation circuit 13, the signal is supplied to the sled motor 5 as a drive signal via a PWM driver 14, and the sled motor 5 is driven at a speed v according to the drive signal.
The rotation is controlled by. Therefore, since the rotational speed v of the thread motor 5 and the output signal e0 have a substantially proportional relationship, when the proportional constant is α, the relationship between the rotational speed v and the output signal e0 is expressed by the following equation. v = α · e0 = α · A · (TE−E) (1)

The speed signal E output from the speed / movement distance calculation circuit 12 is equal to the rotation speed v of the sled motor 5.
Is approximately proportional, and if the proportional constant is k, the relationship between the speed signal E and the rotational speed v is expressed by the following equation. E = k · v (2)

From equation (2), k · v is added to E in equation (1).
Is obtained, the following relationship is obtained. v = α · A · (TE−kv) Accordingly, it can be seen that the rotational speed v is expressed as the following equation, and has a direct proportional relationship with the tracking error signal. v = TE / (k + 1 / (α · A)) (3)

Now, it is assumed that no main spot is formed by the main beam at the center position of the track, and the tracking error signal TE is not zero. At this time, the sled motor 5 rotates by a small angle at the rotation speed v based on the relationship with the tracking error signal TE of the equation (3). And
The tracking error signal TE instantaneously becomes zero,
From the relationship of the expression (3), the rotation speed becomes zero and the sled motor 5 tries to stop the rotation. However, since the track is formed not in a concentric circle but in a spiral shape, the main spot shifts from the center position of the track when the objective lens 44 (FIG. 5) shifts from the center position of the track, and the tracking error signal TE is again generated. To increase. Therefore, the rotation speed is generated again by the increased tracking error signal TE, and the sled motor which is about to stop is again rotated by a small angle.

Since such an operation is always repeated during the tracking operation during recording or reproduction, the sled motor 5 always keeps rotating at a very low rotation speed. Become. Therefore, only when the objective lens shifts to some extent and the magnitude of the drive signal due to the tracking error signal becomes larger than the cogging of the sled motor as in the conventional disk drive, the sled motor rotates and the objective lens does not rotate. Unlike the case where the shift amount is zero, the sled motor always keeps rotating at a low rotation speed. Therefore, at this time, the friction applied to the thread motor 5 is not static friction,
Dynamic friction.

(2) Using shift signal SFS Next, the operation of the sub-loop when the signal input to the positive-phase input terminal a of the operational amplifier 94 is the shift signal SFS will be described. In this case, since the shift signal SFS is used instead of the tracking error signal TE, the rotational speed v of the sled motor 5 and the shift signal S
The relationship with FS is expressed by the following equation in which SFS is substituted for TE in equation (3). v = SFS / (k + 1 / (α · A)) (4)

Similarly, in this case, it is also assumed that a main spot by the main beam is not formed at the center position of the track and the shift signal SFS is not zero. At this time, the sled motor 5 rotates by a small angle at the rotation speed v based on the relationship with the shift signal SFS of the equation (4). Then, the shift signal SFS instantaneously becomes zero, and from the relationship of Expression (4),
The rotation speed becomes zero and the sled motor 5 tries to stop rotating. However, since the tracks are formed not spirally but concentrically, the objective lens 44
The main spot is shifted from the center position of the track by shifting (FIG. 5) from the center position of the track, and the shift signal SFS increases again. Therefore, the rotation speed is generated again by the increased shift signal SFS, and the stopped sled motor is again rotated by a small angle.

Since such an operation is always repeated during the tracking operation during recording or reproduction, the sled motor 5 always keeps rotating at a very low rotation speed. Become. Therefore, only when the objective lens shifts to some extent and the magnitude of the drive signal due to the tracking error signal becomes larger than the cogging of the sled motor as in the conventional disk drive, the sled motor rotates and the objective lens does not rotate. Unlike the case where the shift amount is zero, the sled motor always keeps rotating at a low rotation speed. Therefore, at this time, the friction applied to the thread motor 5 is not static friction,
Dynamic friction.

When the sub-loop of the tracking servo is controlled using the shift signal SFS, unlike the case where the tracking error signal TE is used, the objective lens 4 is controlled.
4 (FIG. 5). That is, the tracking error signal TE is a signal in which the offset, which is the shift amount of the objective lens 44 (FIG. 5), has been eliminated. Therefore, for example, in a portable disk device, as shown in FIG. 15A, gravity is applied in the direction of the arrow, and the optical axis of the light source of the optical pickup 2 (FIG. 1) is located at the track a, and the gravity is reduced. When the center position of the objective lens 44 is located at the track b due to the radial direction of the disk, tracking control is performed with the tracking error signal TE set to zero while the track b is captured.

Accordingly, when the objective lens 44 is located at the center of the track b while the optical axis of the light source is located at the track a, tracking control is performed so that the tracking error signal TE becomes zero. Therefore, at the time of recording, the magnetic head 3 needs to give a magnetic field signal to the track b. In a portable disk device, the direction of gravity may be applied in a direction opposite to the direction of the arrow in FIG. Therefore, in view of such a case, in order to apply a magnetic field over a wide range, the magnetic head 3 needs to increase the size of a coil that generates the magnetic field, as shown in FIG. Thus, enlarging the coil leads to an increase in power consumption and a reduction in the life of a battery used in a portable disk device.

As described above, the tracking error signal TE
Is not suitable for a disk device in which the force applied to the objective lens 44 is not constant, such as a portable type disk device, but is always only in the optical axis direction of the laser beam emitted from the optical pickup 2. It can be used for a home use type disk device to which an external force is applied. Accordingly, the operation of the tracking servo sub-loop using the shift signal SFS indicating the shift amount of the objective lens 44 that can be used in a portable type disk device will be further described.

As shown in FIG. 15B, when gravity is applied in the direction of the arrow and tracking control is not performed, the positional relationship between the optical axis of the light source and the objective lens 44 is determined by using the tracking error signal TE. As in the case of FIG.
The relationship is as shown in FIG. However, when tracking control is performed, the positive-phase input terminal a of the operational amplifier 94
Is a value according to the shift amount of the objective lens 44, not zero. The sub-loop of the tracking servo corresponds to the shift signal SF.
S acts so as to become zero, and the sled motor 5 rotates.

As described above, the rotation of the sled motor 5 moves the optical pickup 2 (FIG. 1) so that the optical axis of the light source is positioned on the track b. That is,
The optical pickup 2 (FIG. 1) is moved so that the optical axis from the light source coincides with the center of the objective lens 44, and tracking is performed with the tracking error signal TE set to zero in a state where they coincide at the center of the track b. Control will be started. Therefore, even if the attitude of the disk device changes, the optical disk has a function of always making the optical axis of the light source coincide with the central portion of the objective lens 44, and the ratio of the formation of the elliptical spot on the disk is reduced. And the range in which the magnetic head 3 generates a magnetic field can be narrowed.

<Long Search> In the long search in the disk device of the present embodiment, similarly to the conventional disk device, after calculating the number of tracks between the original track and the target track, the number of tracks is calculated. The operation of driving the thread motor 5 to move the optical pickup 2 (FIG. 1) is performed. In this embodiment, the long search is performed while detecting the position of the optical pickup 2 (FIG. 1). Such a long search will be described with reference to FIG. 12, FIG. 14, and FIG. FIG. 16 is a diagram illustrating a voltage value of a drive signal applied to the sled motor 5 and a rotation speed of the sled motor 5 during a long search.

The control system of the sled motor 5 in this long search is represented as shown in FIG. That is, the loop is controlled by a loop similar to the sub-loop of the tracking servo. When the switch SW4 is connected to the contact d side, a thread instead of the tracking error signal TE or the shift signal SFS is supplied to the positive-phase input terminal a of the operational amplifier 94. The sled motor drive signal SD generated by the motor drive signal generation circuit 96 is input. At the same time, the amplification degree of the amplifier 95 is switched from A to A1, and the gain of the speed / movement distance calculation circuit 12 is switched from k to k1. or,
The sled motor drive signal generation circuit 96 generates a sled motor drive signal SD according to a command from the control microcomputer 8 (FIG. 1).

At this time, the voltage V applied to the sled motor 5 is expressed by the following equation. V = A1 · (SD−E) = (A1 / (1 + k1 · α · A1)) · SD (5) In the equation (5), the coefficient (A1 / (1 + k1 · α ·
In A1)), k1 and A1 are set so as to be smaller than 1 and usually close to 1 as much as possible. Therefore, normally, the voltage V applied to the sled motor 5 is substantially equal to the sled motor drive signal SD.

The relationship between the rotational speed v of the sled motor 5 and the sled motor drive signal SD is described above.
Or, as in the equations (3) and (4), which are relational equations with the shift signal SFS, the following equation is obtained. v = SD / (k1 + 1 / (α · A1)) (6)

The relationship between the rotation speed v of the sled motor 5 and the sled motor drive signal SD is expressed by the following equation (6), which indicates that the sled motor 5 is speed-controlled by the sled motor drive signal SD. . The fact that the speed of the thread motor 5 is controlled in this manner means that the optical pickup 2 depends on the attitude of the disk device.
Even when gravity is applied in the same direction as the moving direction of FIG. 1 or in the opposite direction, the rotation speed of the sled motor 5 is controlled to be constant.

That is, when gravity is applied in the same direction as the moving direction of the optical pickup 2 (FIG. 1), the thread motor 5
Is controlled so as to decrease the voltage applied to the sled motor 5, and vice versa. Therefore, in the conventional apparatus in which the speed of the sled motor is not controlled, since the influence of gravity is exerted on the rotation speed, the moving distance of the optical pickup varies, but by controlling the speed of the sled motor as in the present embodiment, Since the rotation speed is controlled irrespective of the gravity, it is possible to suppress variation in the moving distance of the optical pickup.

In the long search for controlling the speed of the thread motor 5 as described above, first, when a command is given from the control microcomputer 8 (FIG. 1), the digital servo processing circuit 10 generates the thread motor drive signal SD. The signal is input to the positive-phase input terminal a of the operational amplifier 94. The PWM based on the thread motor drive signal SD
The sled motor 5 is driven to rotate by the processed signal.

At this time, in the main loop of the tracking servo, the switch SW1 (FIG. 8) is connected to the contact d side, and a reference voltage is supplied to the power supply compensation circuit 85 (FIG. 8). Objective lens 44
(FIG. 5) is retained. Incidentally, physically, the objective lens 4
4 (FIG. 5) is displaced by receiving a positive or negative acceleration force.
Then, the speed / movement distance calculation circuit 12 calculates the movement distance of the optical pickup 2 (FIG. 1).

First, the calculation of the moving distance of the optical pickup 2 (FIG. 1) in the speed / moving distance calculating circuit 12 and the use of the result will be described below. First, before performing a long search, it is calculated how many tracks exist between the original track and the target track. At this time,
Assuming that n tracks exist between the original track and the target track, and the track pitch is p μm, the moving distance of the optical pickup 2 (FIG. 1) is n · p μm.

Therefore, the distance by which the sled motor 5 moves the optical pickup 2 (FIG. 1) per rotation is a μm.
Assuming that the number of rotations of the sled motor 5 for moving the optical pickup 2 (FIG. 1) by the moving distance is b, b is expressed by the following equation. b = (n · p) / a

Incidentally, the rotation speed of the thread motor 5 is
As described above, it is detected by the output signals from the Hall elements 11a and 11b. That is, FIGS. 14A and 14B
Output signals P1, P of the Hall elements 11a, 11b
It is detected by the number of zero crossings of 2. Therefore,
Now, assuming that the number of magnetic poles of the N-pole and the S-pole provided on the rotating plate facing the Hall elements 11a and 11b is c-pole, for example, when the output signal P1 of the Hall element 11a detects zero crossings 2c times, Thread motor 5
Has made one rotation. Accordingly, the number d of zero crossings of the output signal P1 or the output signal P2 detected until the optical pickup 2 (FIG. 1) reaches the target track is:
It is expressed by the following equation. d = (n · p · 2c) / a (7)

As described above, the number of times that one of the output signals P1 and P2 of the Hall elements 11a and 11b has zero-crossed is counted, and the counted number is (n · p · 2c) /
At the point a, when the thread motor 5 is stopped, the objective lens 44 (FIG. 5) is positioned near the target track.
Will be located. It should be noted that each of the square wave generation circuits 105 and 106 as shown in FIGS. The zero crossing of one of the output pulse signals R1 and R2 is counted, and the counted number is (n ·
When p · 2c) / a, the thread motor 5 may be stopped.

However, since the value d in the equation (7) rarely becomes a positive integer, the value of the optical pickup 2 per one count of the zero-cross signal is set to a value below the decimal point.
An error is obtained by multiplying the moving amount (a / (2c)) μm in FIG. 1. Therefore, the smaller the movement amount of the optical pickup 2 (FIG. 1) per one count of the zero cross signal, the smaller the error becomes. That is, as the count number per rotation of the thread motor 5 is increased, it is possible to reach a position with higher accuracy near the target track.

As a method of increasing the number of counts per rotation of the thread motor 5 and counting at a finer pitch, there are the following methods. 1. As shown in FIG. 14 (j), the signals R1 and R2 shown in FIGS. 14 (e) and 14 (f)
A signal S that is twice as large as the signal S is generated, and counting is performed using the signal S. 2. Although two-phase detection signals using two Hall elements 11a and 11b are used, detection signals of multiple phases such as three phases in which the number of Hall elements is increased are used. Generate and count two signals. 3. The above 1. Or 2. A signal obtained by further multiplying the frequency of the signal obtained by the above method is generated and counted.

[0233] 1. In the case of, the signals R1 and R2 shown in FIGS. 14E and 14F can be generated by, for example, inputting the signals to an EXOR gate circuit and outputting a signal S which is an exclusive OR thereof. it can. That is, the signals R1, R
When 2 is (H, L) or (L, H),
When the signals R1 and R2 are (L, L) or (H, H), respectively, the signal S as shown in FIG.

[0234] 2. In the case of 1. , The pulse signals R1 and R2 obtained from the two-phase detection signals P1 and P2
As a signal S having a frequency twice as high as that of the pulse signal is generated, for example, by combining a pulse signal obtained from an n-phase detection signal, a signal having a frequency n times the pulse signal obtained from the detection signal is obtained. Generate still,
Since the frequency of the pulse signal obtained from the detection signal is not related to the number of Hall elements, as a result, 1. In this case, a signal having a frequency n / 2 times that of the generated signal S is obtained.

[0235] 3. In the case of, for example, 1. Or 2. The signal generated in the above case and a signal obtained by delaying this signal by a delay circuit are input to an EXOR gate circuit and combined to obtain 1. Or 2. In this case, a signal having twice the frequency of the generated signal can be generated. or,
As another example, a band-pass filter provides: Or 2. In the case of (1), odd harmonic components are extracted from the generated signal, and the waveforms of the harmonic components are obtained. Or 2. In this case, a signal obtained by multiplying the generated signal can be obtained.

Next, the rotation of the sled motor 5 will be described. At this time, the sled motor drive signal SD changes as shown in FIG. 16B, and the amplifier 95 responds accordingly.
The voltage value of the signal for driving the sled motor, which is provided, changes as shown in FIG. First, at point A,
When a command is given from the control microcomputer 8 (FIG. 1) to perform a long search, as shown in FIG. 16B, the sled motor 5 The rotation speed gradually increases.

At this time, the rotation speed of the sled motor 5 rises slightly later than the sled motor drive signal SD. Therefore, since the speed signal E rises later than the sled motor drive signal SD, the value of the difference signal output from the operational amplifier 94, which is the difference between the sled motor drive signal SD and the speed signal E, increases. Therefore, before the optical pickup 2 (FIG. 1) reaches from the point A to the point B, first, the sled motor 5 output from the amplifier 95 is used.
Is instantaneously increased as shown in FIG. 16 (a). After that, since the speed signal E becomes a value proportional to the sled motor drive signal SD, the value of the difference signal output from the operational amplifier 94, which is the difference between the sled motor drive signal SD and the speed signal E, becomes smaller. Therefore, the voltage value of the signal for driving the sled motor 5 output from the amplifier 95 decreases as shown in FIG.

At this time, if the rotation speed of the sled motor 5 rises steeply, a binding current flows through the sled motor 5. In order to avoid such a constrained current, a sled motor drive signal SD as shown in FIG.
, The slope of the rise of the rotation speed of the thread motor 5 is provided. The value of the thread motor drive signal SD from the point A to the point B has a maximum rate of change of the rotation speed of the thread motor 5 within a range in which the constrained current does not flow, in consideration of variations in the characteristics of the thread motor 5 during mass production. Is set to a value such that

As shown in the equation (6), the sled motor drive signal SD is a speed control signal for the sled motor 5. That is, the rotation speed v of the sled motor 5 is controlled to a speed obtained by multiplying the sled motor drive signal SD by the coefficient (see the equation (6)). Therefore, at the time of rising, PW
Since the voltage applied from the M driver 14 (FIG. 1) must exceed the starting voltage of the sled motor 5, the sled motor drive signal SD does not apply a voltage to the sled motor 5 from the PWM driver 14 (FIG. 1). That is, first, after a voltage equal to or higher than the starting voltage is applied to the sled motor 5 and the sled motor 5 starts rotating, the speed of the sled motor 5 is controlled by the sled motor drive signal SD.

As described above, when the sled motor 5 starts rotating, the friction applied to the sled motor 5 shifts from static friction to dynamic friction, and the load applied to the sled motor 5 is extremely reduced. At this time, if the voltage applied to the sled motor 5 remains at the starting voltage, the number of revolutions rapidly increases. However, in the present embodiment, after the sled motor 5 is started, the speed is controlled by the sled motor drive signal SD. Since the control is performed, the voltage applied to the sled motor 5 drops instantaneously. Thereafter, the voltage applied to the sled motor 5 increases to a certain value indicating a gradient substantially similar to the gradient of the sled motor drive signal SD, and then decreases. By controlling the speed of the sled motor 5 in this manner, it is possible to prevent the rotation speed of the sled motor 5 from suddenly increasing in a state where the voltage applied to the sled motor 5 exceeds the starting voltage. Large current in the sled motor 5 can be prevented.

Thereafter, when the sled motor drive signal SD reaches a predetermined value as shown in FIG. 16B, the signal for driving the sled motor 5 supplied from the amplifier 95 is also substantially constant as shown in FIG. Voltage. During this time, an inter-axis loss generated between the axes is compensated for by a difference voltage that is a difference between a voltage applied to the sled motor 5 and a starting voltage of the sled motor 5. When the optical pickup 2 (FIG. 1) arrives at the point C, a count value such as a zero-cross signal given to the control microcomputer 8 (FIG. 1) from the speed / movement distance calculation circuit 12 is set in advance. That is, the control microcomputer 8 (FIG. 1) detects that the first predetermined value has been reached. At this time, a command is given from the control microcomputer 8 (FIG. 1) to the sled motor drive signal generation circuit 96, and the value of the sled motor drive signal SD gradually decreases as the rotation speed of the sled motor 5 elapses with time. As shown in FIG. 16B, the optical pickup 2 (FIG. 1) descends from the point C to the point D.

An optical pickup 2 is moved from the point C to the point D.
When the slant of the lower right during the movement of FIG. 1 is steep, the sled motor 5 itself moves to FIG.
The electromotive force represented by the broken line in (c) exceeds the applied voltage represented by the solid line in FIG. 16 (c), and a voltage in the direction opposite to the rotation direction is applied. Therefore, the value of the thread motor drive signal SD from the point C to the point D is always equal to the voltage applied to the thread motor 5 from the point C to the point D in consideration of the variation in the characteristics of the thread motor 5 during mass production. In a range higher than the voltage due to the electromotive force, the change rate of the rotation speed of the sled motor 5 is set to a value that maximizes the rotation speed.

As shown in FIG. 16B, when the value of the sled motor drive signal SD decreases, the value of the speed signal E decreases with a delay because the sled motor 5 cannot instantaneously reduce its rotational speed. . Therefore, as shown in FIG. 16A, the voltage value of the signal for driving the sled motor 5 supplied from the amplifier 95 after the time when the vehicle reaches the point C becomes a negative value. When the rotation speed of the sled motor 5 is reduced, the speed signal E also becomes the sled motor drive signal S
Since the voltage drops in proportion to D, the voltage value of the signal for driving the sled motor 5 supplied from the amplifier 95 becomes constant at a negative value.

When the optical pickup 2 (FIG. 1) arrives at the point D, the voltage applied to the sled motor 5 becomes the minimum necessary for operating the sled motor 5 as shown in FIG. The sled motor drive signal SD is set as shown in FIG. The minimum operating voltage set at this time is, for example, approximately 1/10 of the voltage applied between the point B and the point C in consideration of variations in the motor and load of the thread motor 5 during mass production. Therefore, it is set higher than the true minimum operating voltage. Therefore, after the optical pickup 2 (FIG. 1) reaches the point D, the value of the sled motor drive signal SD is changed so that the minimum operating voltage is applied for a certain period of time.
By setting as shown in (b), the sled motor 5 is driven at a very low rotation speed.

Since the rotation speed of the sled motor 5 becomes constant later than the time when the vehicle arrives at the point D, the speed signal E decreases for a short time after the vehicle arrives at the point D, and then becomes a constant value. Therefore, since the difference between the sled motor drive signal SD and the speed signal E is a positive value, the voltage of the signal for driving the sled motor 5 supplied from the amplifier 95 is slightly delayed after reaching the point D. As shown in FIG. 16A, the value is constant at a positive value.

Thereafter, when the optical pickup 2 (FIG. 1) arrives at the point E, the count value such as the above-mentioned zero-cross signal in the speed / movement distance calculation circuit 12 becomes the final total count number corresponding to the target track position. The control microcomputer 8 (FIG. 1) detects that a predetermined second predetermined value has been reached. At this time, the value of the sled motor drive signal SD is set to 0 as shown in FIG. Since the voltage applied to the sled motor immediately before the point E is the minimum operating voltage, the inertia of the sled motor 5 is very small. Therefore, when the value of the thread motor drive signal SD is set to 0 at the point E, the rotation stops immediately. Incidentally, the applicant has obtained through an experiment that when the sled motor is driven by the driving signal as shown in FIG. 16A, the optical pickup reaches the range of ± 30 from the target track. .

Here, the setting of the first predetermined value detected at the point C will be described. The first predetermined value is set at a value which is a few percent (approximately 50 to 90%) of the second predetermined value which is the final total count number. The percentage for generating the first predetermined value differs depending on the number. This percentage increases as the number of tracks crossing during the search increases.

This is because the rotation speed and applied voltage of the sled motor 5 between the point B and the point C during the long search are not limited to the number of tracks traversed at the time of the search, and are substantially constant. The optical pickup 2 (FIG. 1) which lowers the rotation speed of the sled motor 5 after the time from the point D to the optical pickup 2 (FIG. 1) which sets This is because the time to reach the point is not so affected by the large number of tracks crossing during the search.

In the above description, C is determined by the first predetermined value.
Having determined the point, another example of determining the point C will be described below. In this example, there is a point where the count number of the zero-cross signal or the like reaches a count number of a half of the final total count number from the point B at which the constant drive voltage starts to be applied. Assuming that the time at which this count is reached is time T, time T after the optical pickup 2 (FIG. 1) reaches point B is reached.
The time Ta up to is measured. And the optical pickup 2
This measured time Ta after (FIG. 1) reached point B
A position at which the optical pickup 2 (FIG. 1) arrives at a time 2Ta twice as long as the point C is defined as a point C.

At this time, the absolute value of the slope indicating the rate of increase of the drive voltage from point A to point B and the slope indicating the rate of decrease of the drive voltage from point C to point D are set to be substantially the same. There is a need to. When the point C is set in this way, it is not necessary to switch the percentage according to the number of lines crossing at the time of search and set the first predetermined value.

As described above, the final total count number is set to the second predetermined value, and the optical pickup 2 (FIG. 1) when the count number of the zero-cross signal or the like reaches the second predetermined value. The position is designated as point E, and at this point E, FIG.
As shown in FIG. 6B, the value of the sled motor drive signal SD is instantaneously switched to 0, and the rotation of the sled motor 5 is stopped. At this time, the rotation speed of the sled motor 5 is instantaneously switched to 0 by the sled motor drive signal SD, even though the minimum operating voltage applied to the sled motor 5 is a voltage, however, the back electromotive force is generated inside the sled motor 5. When power is generated, a large current of several hundred mA flows.

Therefore, when the disk device is used in such an operating state, an optical pickup 2 is provided at point E as a power supply circuit for supplying power to the disk device.
A power supply circuit is required to allow a large current to flow when (FIG. 1) arrives. Further, when a secondary battery such as a dry battery is used as the power supply, it is necessary to set a lifetime voltage that allows the large current. However, at present,
Since the internal resistance of the secondary battery is also increasing, it is necessary to greatly increase the lifetime voltage of the secondary battery to allow a large current. Therefore, although a voltage that can be sufficiently used in other operations can be supplied, the voltage generated by the flow of the large current is detected as the life voltage set as described above, and the voltage of the secondary battery is detected. Exchange may be required. Therefore, in order to eliminate such inconvenience, it is necessary to prevent a large current flowing when the optical pickup 2 (FIG. 1) reaches the point E in FIG. 16A.
The means for preventing this will be described below.

(1) First Means for Preventing Generation of Large Current First, the first means will be described below. This first
Means, when the count number of a zero cross signal or the like becomes one less than the final total count number, sets the gain of the speed / movement distance calculation circuit 12 to, for example, about 1/10 of the original gain k1. So, lower significantly.
At this time, the position where the optical pickup 2 (FIG. 1) reaches is point E. At the same time, the value of the sled motor drive signal SD is instantaneously set to 0 as shown in FIG.

As described above, the speed / movement distance calculation circuit 12
Greatly reduces the response of the control loop for controlling the sled motor 5. Therefore, although the sled motor drive signal SD is instantaneously reduced to 0, since the control response is slow, it takes time for the applied voltage applied to the sled motor 5 to reach 0V. That is, since the voltage applied to the sled motor 5 gradually decreases, the back electromotive force from the coil of the sled motor 5 hardly occurs.

At this time, the sled motor 5 still tries to continue rotating, but the optical pickup 2 (FIG. 1)
Since the voltage applied before reaching the point E is the lowest operating voltage, the stop voltage is immediately reached even if the rate of decrease in the voltage applied to the sled motor 5 is low. Then, the rotation of the sled motor 5 is stopped, and the generation of the electromotive force by the sled motor 5 itself is eliminated. That is, there is no situation where the electromotive force of the sled motor 5 itself exceeds the applied voltage from the time when the optical pickup 2 (FIG. 1) reaches the point E to the time when the applied voltage to the sled motor 5 becomes 0 V. Current can be prevented from flowing.

(2) Second Means for Preventing Generation of Large Current Next, the second means will be described below. This second
Means short-circuits the input terminals at both ends of the sled motor 5 at time E when the count number of the zero-cross signal or the like becomes the final total count number. At this time, two switches are provided between the power supply and two input terminals of the sled motor 5 so that no voltage is applied to the sled motor 5 from the power supply, and a switch for short-circuiting the two input terminals of the sled motor 5 is provided. Is provided. By turning off two switches connected to the power supply and turning on a switch provided between the input terminals to short-circuit the input terminals, it is possible to prevent a large current from flowing.

When the optical pickup 2 (FIG. 1) reaches the point E, the value of the sled motor drive signal SD is set to 0.
Then, by setting the voltage value of the signal for driving the sled motor 5 supplied from the amplifier 95 to 0 V for about 10 msec, the sled motor 5 is short-circuited. Therefore, at this time, as in the case where the above three switches are provided, a short-circuit state can be achieved.
There is no need to provide the above three switches. By creating a short circuit state in this manner, a large current can be prevented from flowing.

After the rough search from the point A to the point E is performed as described above, the application of the voltage to the sled motor 5 by the sled motor drive signal SD is stopped, and the rotation of the sled motor 5 is stopped. By the way, in the conventional apparatus, in performing a long search, it is necessary to provide a waiting time of several tens msec in order to wait for the rotation stop of the thread motor after the coarse search and to wait for the vibration of the objective lens to be alleviated. However, in the disk device of the present embodiment, since the applied voltage immediately before the stop of the thread motor 5 is the minimum operating voltage, the rotation speed of the thread motor 5 is very low, and the optical pickup 2 (FIG. The inertial force of FIG.
4 (FIG. 5) is also small. Therefore, the waiting time in the disk device of the present embodiment is reduced to about 10 msec.

After the waiting time has elapsed, the interval at which the tracking error signal crosses zero is measured.
When this interval becomes equal to or longer than a predetermined time, the switch SW1 (FIG. 8) is connected to the contact c side, and pull-in by the tracking servo is started. That is, when the moving speed of the objective lens 44 (FIG. 5) becomes lower than a predetermined speed, the hold of the objective lens 44 (FIG. 5) at the reference position is released, and pull-in by the tracking servo is started.
The time from the elapse of the waiting time to the start of the pull-in is also shortened for the same reason as described above for shortening the waiting time.

As described above, after the pull-in is performed by the tracking servo, the number of tracks that is the difference between the track drawn by the tracking servo and the target track is calculated, and the above-described kick operation is repeated to change to the target track. The objective lens 44 (FIG. 5) is moved. At this time, since the number of tracks that are the difference between the track drawn in by the tracking servo and the target track is within 30 as described above, it is possible to reduce the number of times the kick operation is repeated as compared with the related art, The time spent for a long search can be reduced.

<Rotation control of spindle motor>
The rotation control of the spindle motor 4 (FIG. 1) during a long search, particularly during a coarse search, will be described with reference to the drawings. FIG. 17 shows disk 1 in zone CLV control.
FIG. 2 is a diagram showing a relationship between a radial direction of FIG. 1 and a rotation speed.
FIG. 18 is a diagram showing the relationship between zones and their permissible rotational speeds in the disk 1 (FIG. 1) having a super-resolution layer. FIG. 19 shows the spindle motor 4 (FIG. 1) when searching from the inner circumference to the outer circumference of the disk 1 (FIG. 1).
FIG. 5 is a diagram showing control of the rotation speed of the motor. FIG. 20 is a diagram showing control of the rotation speed of the spindle motor 4 (FIG. 1) when performing a search from the outer circumference to the inner circumference of the disk 1 (FIG. 1).

As described above, when the tracking operation is performed, such as during recording or reproduction, the spindle motor 4 (FIG. 1) is PLL-controlled by ADIP data. When the disk 1 (FIG. 1) is rotated while the tracking operation is not performed, the spindle motor 4 (FIG. 1) is driven to rotate by the above-described FG servo.

As described above, the disc 1 (FIG. 1) used in this embodiment is composed of a super-resolution layer and a recording layer, and when the disc 1 (FIG. 1) is reproduced, the disc 1 (FIG. 1) is used. It is necessary to control the output of the irradiated laser beam so that the temperature of the reproducing section in FIG. 1) is lower than the Curie point of the recording layer and higher than the Curie point of the super-resolution layer.
Therefore, the output of the irradiated laser beam is larger than when reproducing a disc having no super-resolution layer.

Further, the rotation of the disk 1 (FIG. 1) is controlled by the above-described zone CLV control. The relationship between each zone of the disk 1 (FIG. 1) and the rotational speed of the spindle motor 4 (FIG. 1) in that zone is as shown in FIG. As shown in FIG. 17, the disk 1 (FIG. 1) is controlled such that the rotation speed of the spindle motor 4 (FIG. 1) is constant within one zone, and the overall linear velocity is constant. Is controlled as follows. Accordingly, the rotational speed of the spindle motor 4 (FIG. 1) is controlled to be high in the zone located on the inner peripheral side, and conversely, the rotational speed of the spindle motor 4 (FIG. 1) is controlled to be low in the zone located on the outer peripheral side. Is done.

Now, it is assumed that the above-described long search has been performed from the position where zone 0, which is the TOC region 22 (FIG. 2), to the position where zone 10 is located on the innermost circumference side of the main information region 23 (FIG. 2). . Also, the appropriate rotation speed of the spindle motor 4 (FIG. 1) in the zone 0 is set to 1200 rpm,
The appropriate rotation speed of the spindle motor 4 (Fig. 1) at 24
00 rpm.

At this time, the optical pickup 2 is
When the rotation speed of the spindle motor 4 (FIG. 1) is changed to 2400 rpm after the arrival of FIG. 1 (FIG. 1), the irradiation time of the laser beam emitted from the optical pickup 2 (FIG. 1) in the zone 5 to the zone 10 becomes longer. If the temperature of the recording layer at the irradiated location becomes higher than the Curie point, recorded data may be erased.

In order to avoid data erasure, the output of the laser beam is reduced during the coarse search, and after the optical pickup 2 (FIG. 1) reaches the zone 10, the output of the laser beam is reduced. Although there is a method of raising the output, it takes time to raise the output of the laser beam to a predetermined output, so that the time spent for a long search is prolonged.

However, in this embodiment, even if a long search is performed during reproduction, the data in each zone is not erased, and the rotation speed of the spindle motor 4 (FIG. 1) in each zone is higher than the allowable rotation speed. Then, when the optical pickup 2 (FIG. 1) reaches each zone, the spindle motor 4 (FIG. 1) is rotated to prevent erasure of data at a location where the laser beam is irradiated to that zone.
The operation of the spindle motor 4 (FIG. 1) at this time will be described below. The allowable rotation speed is approximately 0.7 Nrpm, which is approximately 0.7 times the rotation speed when the optimum rotation speed of a certain zone is Nrpm. In FIG. 18, the optimum rotation speed of the zone is indicated by a solid line. The permissible rotational speed of the zone is indicated by a dashed line.

(1) Rotation control of spindle motor at the time of search in the outer circumferential direction 1 of control operation of rotation speed of spindle motor 4 (FIG. 1) when searching from a certain position of zone 10 to a certain position of zone 0 An example will be described with reference to FIG. That is, the operation when performing a rough search from the track in the inner zone to the track in the outer zone will be described. Zone 0 is the TOC area 22
(FIG. 2), there is generally no such search, but the UTOC area 22 (FIG. 2)
In the case of a disc on which information is recorded, such a search is performed when such a disc is loaded.

First, a long search is instructed, the number of tracks crossed by the optical pickup 2 (FIG. 1) from the original track to the target track is detected, and based on the number of tracks, the optical pickup 2 (FIG. 1) is detected. ) Is calculated. Next, a certain zone of the target track is detected, and the number of zones from a certain zone of the original track to a certain zone of the target track is detected.

Based on the detected moving distance of the optical pickup 2 (FIG. 1) and the number of zones, the spindle motor 4 (FIG. 1)
The number of times the rotation speed is reduced is determined, and the position where the rotation speed is reduced is determined. In the example of FIG. 19,
The number of times that the rotation speed of the spindle motor 4 (FIG. 1) is reduced is set to three times, and the position where the rotation speed is reduced is determined by the optical pickup 2 (FIG.
It is assumed that the vehicle is approaching zone 1, passing zone 5 and approaching zone 4, and passing zone 2 and approaching zone 1.

The time required for lowering the rotation speed varies depending on the degree of reduction in the rotation speed of the spindle motor 5 (FIG. 1). 2 (FIG. 1) determines the number of times and position at which the rotational speed is reduced. Note that the smaller the detected moving distance or the number of zones of the optical pickup 2 (FIG. 1), the smaller the number of times the rotational speed of the spindle motor 5 (FIG. 1) is reduced.

The above calculations and settings are performed by the control microcomputer 8 (FIG. 1). The position at which the determined rotation speed of the spindle motor 4 (FIG. 1) is reduced is detected by the speed / movement distance calculation circuit 12 by detecting the distance moved by the optical pickup 2 (FIG. 1) as described above. Is detected. The result of this detection is the control microcomputer 8
(FIG. 1), when a position at which the rotational speed is reduced is detected, a signal representing the set rotational speed is set so that the rotational speed is reduced to the rotational speed set by the control microcomputer 8 (FIG. 1). Provided to the processing circuit 9 and the spindle motor 4
(FIG. 1) is controlled by the FG servo described above.

By doing so, the disk 1
When a long search is performed from the inner circumference side to the outer circumference side (FIG. 1), when the optical pickup 2 (FIG. 1) passes through each zone, the rotation speed of the spindle motor 4 (FIG. 1) in each zone increases. Since it does not fall below the allowable rotation speed,
Data on the portion of the disk 1 (FIG. 1) irradiated with the laser beam is not erased. When the optical pickup 2 (FIG. 1) arrives near the target track, the spindle motor 4 is driven at the optimum rotational speed in the zone where the target track exists. Immediately after (FIG. 5) is pulled in, the information of the track can be read. Further, since it is not necessary to reduce the output of the laser beam, it is not necessary to increase the output of the laser beam when the optical pickup 2 (FIG. 1) reaches near the target track.

(2) Rotation control of spindle motor at the time of search in the inner circumferential direction 2-1. First Example of Spindle Motor Rotation Control During Search in the Inner Circumference First, the control operation of the rotation speed of spindle motor 4 (FIG. 1) when searching from a certain position in zone 0 to a certain position in zone 10 is described. One example will be described with reference to FIG. That is, an operation when performing a rough search from a track in the outer zone to a track in the inner zone will be described.

First, when a long search is instructed, a certain zone of the target track is detected, and a signal representing an optimum rotation speed of the zone is given to the signal processing circuit 9 (FIG. 1), and the spindle motor 4 (FIG. The rotation speed of 1) is raised to this optimum rotation speed by the above-mentioned FG servo. Then, while changing the rotation speed of the spindle motor, the long search operation described above is performed. By doing so, as is clear from FIG. 20, the rotation speed of the spindle motor 4 (FIG. 1) does not fall below the allowable rotation speed, so that the laser beam on the disk 1 (FIG. 1) is irradiated. The data at the location is not erased.

2-2. Second Example of Rotation Control of Spindle Motor During Search in Inner Circumference Next, control operation of the rotation speed of spindle motor 4 (FIG. 1) when searching from a certain position of zone 0 to a certain position of zone 10 The two examples will be described with reference to FIG. The example of the rotation control is similar to the rotation control when performing the rough search from the track in the inner zone to the track in the outer zone described above. First, the rotation control is performed from the original track to the target track. The number of tracks and the moving distance of FIG. 1 are calculated, the zone of the target track is detected, and the number of zones from the zone of the original track to the zone of the target track is detected.

The detected optical pickup 2
From the movement distance and the number of zones in FIG. 1, the spindle motor 4 (FIG. 1) reverses the rotation control when performing a rough search from a track in the inner zone to a track in the outer zone. The number of times to increase the rotation speed is determined, and the position at which the rotation speed is increased is determined. When the above calculations and settings are performed by the control microcomputer 8 (FIG. 1), the determined position for increasing the rotation speed of the spindle motor 4 (FIG. 1) is, as described above, a speed / movement distance calculation circuit. 12. As described above, when the position at which the rotation speed is increased is detected, the spindle motor 4 (FIG. 1) is controlled by the above-described FG servo so as to increase the rotation speed to the rotation speed set by the control microcomputer 8 (FIG. 1). Is done.

When a long search is performed from a certain zone of the original track to a certain zone of the target track, the control procedure for each combination of the two zones is performed in advance by the control microcomputer 8 (FIG. 1). When the target track is recognized from the original track zone, an appropriate control means is selected from a plurality of control means stored in the control microcomputer 8 (FIG. 1). Can be
The rotation control of the spindle motor 4 (FIG. 1) during the long search can be easily performed. Further, when storing the control means in the control microcomputer (FIG. 1),
Since FIG. 1 is standardized by the zone CLV, it is possible to easily program the rotation control of the spindle motor 4 (FIG. 1).

<Operation after Power-On of Disk Device> The operation of the disk device of this embodiment after power-on will be described with reference to the drawings. FIG. 21 is a timing chart showing the relationship between the output signals of the respective units at this time. FIG. 25 is a diagram showing the relationship between each zone of the disk 1 (FIG. 1) and the rotation speed. First, as shown in FIG.
When the power is turned on at time Ta, a rough search is performed on the TOC area 22 (FIG. 2) corresponding to zone 0 of the disk 1 (FIG. 1). This rough search, as described above,
The TOC area 22 where the lead-in switch 32 (FIG. 1) provided opposite to the surface of the disk 1 (FIG. 1) switches.
The optical pickup 2 (FIG. 1) is moved by the sled motor 5 (FIG. 1) to the vicinity (FIG. 2).

At time T immediately after the power is turned on,
21B, as shown in FIGS. 21C and 21E, the thread motor 5 (FIG. 1) and the spindle motor 4 (FIG. 1) are simultaneously activated. Thus, by simultaneously starting the sled motor 5 (FIG. 1) and the spindle motor 4 (FIG. 1),
Reduce startup time after power-on. Thereafter, the above-described rough search is performed by the sled motor 5 (FIG. 1), and when the reed switch 32 is switched at time Tc as shown in FIG. 21B, the driving of the sled motor 5 is stopped.

Also, the spindle motor 4 (FIG. 1)
As shown in FIG. 1 (e), a forced acceleration operation in which a constant voltage is applied as a drive voltage is performed from time Tb to time Td, and while the forced acceleration operation is being performed, FIG.
The pulse interval of the FG signal indicating the rotation speed of the spindle motor 4 output as described above is monitored by the control microcomputer 8 (FIG. 1). At this time, when the pulse interval of the FG signal becomes equal to or less than a predetermined value (time Td), the rotation control of the spindle motor 4 (FIG. 1) is switched to the FG control. still,
The pulse of the FG signal generated as shown in FIG. 5D is hereinafter referred to as “FG pulse”.

For example, the optimum rotation speed of the disk 1 (FIG. 1) corresponding to the TOC area 22 (FIG. 2) in the zone 0 is 1200 rpm, that is, the disk 1 (FIG. 1) rotates 20 rotations per second. In this case, it is assumed that the rotation speed is the optimum rotation speed, and the number of FG pulses generated per rotation of the disk 1 is six. Furthermore, the rotation speed of the disk 1 (FIG. 1), which is the timing for switching the rotation control operation of the spindle motor 4 (FIG. 1) from the forced acceleration operation to the FG control operation, when the rotation speed is 5 times per second, that is, 30
Set to 0 rpm.

At this time, when 30 FG pulses are generated per second, the rotation control operation of the spindle motor 4 (FIG. 1) is switched from the forced acceleration operation to the FG control operation. Accordingly, the pulse interval when switching the rotation control operation of the spindle motor 4 (FIG. 1) from the forced acceleration operation to the FG control operation is 33 msec, and the control microcomputer 8
When the pulse interval monitored in (FIG. 1) becomes 33 msec or less, the mode is switched to the FG control by the signal processing circuit 9.

Then, as shown in FIG.
From the time Te to the spindle motor 4 (FIG. 1)
When the control reaches the first predetermined rotation speed in zone 0 shown in FIG. 25 at time Te, as shown in FIG. 21F, the laser driver 31 (FIG. 1) controls the control microcomputer 8 (FIG. 1).
And the laser beam irradiation is started. The first predetermined rotation speed is a rotation speed higher than the above-mentioned allowable rotation speed in each zone and lower than the optimum rotation speed, and a laser beam is irradiated at the time of search to erase recorded data. It is a rotation speed that is not performed. At this time, the spindle motor 4
The rotation speed of FIG. 1 is the highest rotation speed at which the data of the zone reached by the optical pickup 2 (FIG. 1) can be read, and is lower than the second predetermined rotation speed as shown in FIG. Check if there is.

Thereafter, as shown in FIG. 21 (g), the control microcomputer 8 (FIG. 1) controls the digital servo processing circuit 1
0 (FIG. 1) is instructed to perform a focus search. This focus search is an operation of moving the objective lens 44 (FIG. 5) up and down in the optical axis direction to focus the laser beam applied to the disk 1 (FIG. 1).
And when the laser beam is in focus,
The focus search servo is closed by the digital servo processing circuit 10 (FIG. 1).

As described above, when the focus search servo is closed, a focus error signal is generated by the RF processing circuit 6 (FIG. 1) from the light detection signal output from the optical pickup 2 (FIG. 1). The focus error signal is converted into a digital signal by the AD converter 7 (FIG. 1). After the focus error signal converted into the digital signal is equalized by the digital servo processing circuit 10 (FIG. 1), the focus error signal is subjected to PWM processing by the PWM signal processing circuit 13 (FIG. 1) and given to the PWM driver 14 (FIG. 1). Can be Then, the focus coil of the optical pickup is driven by the PWM driver 14, the objective lens 44 (FIG. 5) is controlled up and down, and the focusing control is performed so that the laser beam is always focused.

Then, as shown in FIG. 21 (g), after closing the main loop of the tracking servo, the thread servo which is a sub-loop of the tracking servo is closed to perform tracking control. At this time, the rotation speed of the spindle motor 4 (FIG. 1) is controlled by the FG.
The ADIP data is read and its address is confirmed. From the confirmed address, the optical pickup 2
When it is confirmed that (FIG. 1) is tracking the TOC area 22 (FIG. 2), the rotation control of the spindle motor 4 (FIG. 1) is performed at time Tf as shown in FIG. The control is switched to the PLL control.

Thus, the spindle motor 4 (FIG. 1)
Becomes PLL controlled, as described above, T
After the TOC information and UTOC information in the OC area 22 (FIG. 2) are read, the disk device enters a standby state. By performing such control, the standby time can be reduced, and the disk 1 (FIG. 1) can be placed in the standby state without erasing the data recorded therein.

<Operation when Stopping Disk> Next, the operation when the disk mounted on the disk device is stopped will be described with reference to the drawings. FIG. 22 is a timing chart showing the relationship between the output signals of the respective units at this time. Now, as shown in FIG. 22C, based on the synchronization signal recorded on the disk 1 (FIG. 1), the spindle motor 4 (FIG. 1)
It is assumed that the control microcomputer 8 (FIG. 1) instructs to stop the disk 1 (FIG. 1) at the time Ta when the data is recorded or reproduced under the L control.

At this time Ta, the rotation control of the spindle motor 4 (FIG. 1) is performed as shown in FIG.
The control is switched from the L control to the FG control, and the laser driver 31 (FIG. 1) is controlled to turn off the laser beam as shown in FIG. This time Ta
For a certain period from time Tb to time Tb, the rotation speed of the spindle motor 4 (FIG. 1) is 90% of the optimum rotation speed of the zone.
The FG control is performed by the signal processing circuit 9 (FIG. 1) so that the rotation speed becomes. Then, at time Tb, the signal processing circuit 9 (FIG. 1) performs FG control so that the rotation speed of the spindle motor 4 (FIG. 1) is reduced to the first predetermined rotation speed.

Then, at time Tc when a predetermined time has elapsed since the rotation speed of the spindle motor 4 (FIG. 1) became the first predetermined rotation speed, the power is turned off as shown in FIG. Then, when the power is turned off, FIG.
As shown in (b), the spindle motor 4 (FIG. 1) stops by inertia. In this way, by stopping the rotation of the disk 1 (FIG. 1) while performing FG control without applying a sudden brake and stopping, abrupt voltage fluctuation at the time of rotation stop in each part of the disk device is achieved. Can be prevented.

<Operation When Rotation Starts After Disk Stop Operation> The operation when the rotation of the disk 1 (FIG. 1) is stopped and then started again will be described with reference to the drawings. FIG. 23 is a timing chart showing the relationship between the output signals of the respective units at this time. FIG. 24 is a timing chart showing the relationship between the output signals of the respective units at this time.

First, as shown in FIG. 23 (b), when the spindle motor 4 (FIG. 1) is stopped due to inertia and the rotational speed of the spindle motor 4 (FIG. 1) has not been reduced so much, The operation when the rotation is started will be described. At this time, first, at time Ta, when a rotation start command is given by the control microcomputer 8 (FIG. 1), the power is turned on as shown in FIG.
The FG control of the spindle motor 4 (FIG. 1) is performed by the signal processing circuit 9 as shown in FIG. 23C so that the rotation speed becomes the first predetermined rotation speed.

Then, at time Ta, the spindle motor 4
When the rotation speed of FIG. 1 reaches the first predetermined rotation speed, the laser driver 31 is turned on in the same manner as the above-described operation at the time of turning on the power.
Is controlled, and a laser beam is irradiated as shown in FIG. Then, similarly to the above-described operation at the time of turning on the power, after confirming whether the rotation speed of the spindle motor 4 (FIG. 1) is lower than the second rotation speed, the focus servo and the tracking servo are closed, and the ADIP data is read. The address is confirmed. Then, at time T
23C, the spindle motor 4 (FIG. 1)
PLL control is performed as shown in FIG.

Next, as shown in FIG. 24 (b), when the spindle motor 4 (FIG. 1) is stopped due to inertia and the rotation speed of the spindle motor 4 (FIG. 1) is considerably reduced, the rotation is resumed. The operation at the time of starting will be described. At this time, first, at time Ta, when a rotation start command is given by the control microcomputer 8 (FIG. 1),
As shown in FIG. 24A, the power is turned on, and then the spindle motor 4 (FIG. 1) performs a forced acceleration operation in which a constant voltage is applied as a drive voltage as shown in FIG.
Then, similarly to the operation at the time of turning on the power, when the pulse interval of the FG pulse becomes equal to or smaller than a predetermined value at time Tb as shown in FIG. 24B, the spindle motor 4 (FIG. 1) as shown in FIG. ) Is subjected to FG control by the signal processing circuit 9 so that the rotation speed becomes the first predetermined rotation speed.

At time Tc, the spindle motor 4
When the rotation speed of FIG. 1 reaches the first predetermined rotation speed, the laser driver 31 is turned on in the same manner as the above-described operation at the time of turning on the power.
Is controlled, and a laser beam is irradiated as shown in FIG. Then, similarly to the above-described operation at the time of turning on the power, after confirming whether the rotation speed of the spindle motor 4 (FIG. 1) is lower than the second rotation speed, the focus servo and the tracking servo are closed, and the ADIP data is read. The address is confirmed. Then, at time T
At d, the spindle motor 4 (FIG. 1) is PLL-controlled as shown in FIG.

[0298]

According to the disk drive of the present invention, since the speed of the sled motor is controlled, the rotation of the sled motor is controlled by using the tracking error signal or the shift signal as the speed control signal even in the non-rotational load due to cogging. Will continue to do so. Therefore, by using the cogging of the thread motor, the shift amount of the objective lens can be made very fine compared to a disk device in which the thread motor is rotated by a predetermined angle when the shift amount of the objective lens becomes a predetermined value. Can be controlled to a range. Also, since the sled motor always keeps rotating at a very low rotational speed, only a small amount of power needs to be supplied to the sled motor. Therefore, unlike a disk device in which the sled motor is rotated at a predetermined angle by cogging according to the shift amount of the objective lens, unnecessary power is not continuously supplied even when the sled motor is not rotating, and power consumption is suppressed. be able to.

When the sled motor is driven by using the shift signal, the speed of the sled motor is controlled by the shift signal. Therefore, an external force such as gravity is applied to the objective lens, and the optical axis and the light source When the optical axis shifts, the sled motor is rotated at a speed corresponding to the shift amount, which is the shift amount, so that the shift amount becomes zero. Therefore, since the influence of such an external force can be prevented, the objective lens can accurately track regardless of the attitude of the disk device. Therefore, in a disk device that records data on a track irradiated by an optical pickup by a magnetic coil or the like, it is not necessary to increase the size of the magnetic coil.
Unnecessary increase in magnetic radiation is not caused, and the power consumed by the magnetic coil can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the relationship between the internal structure of a disk device and a disk.

FIG. 2 is a plan view showing a configuration of a recording area of the disc.

FIG. 3 is a diagram showing a configuration of a track on a disk.

FIG. 4 is a diagram showing a relationship between a super-resolution layer and a recording layer formed on a disc.

FIG. 5 is an external perspective view showing the internal configuration of the optical pickup.

FIG. 6 shows a second example of the laser beam passing through the second diffraction grating.
The figure which shows the positional relationship of the incident position with respect to a photodetector.

FIG. 7 is a diagram showing a relationship between a main spot and a sub spot formed on a track of a disk, and a circuit for generating a tracking error signal and a shift signal.

FIG. 8 is a block diagram showing an internal configuration of a digital servo processing circuit.

FIG. 9 is a timing chart of each signal in a single kick operation.

FIG. 10 is a timing chart of each signal in a double kick operation.

FIG. 11 is a timing chart of each signal in the six kick operation.

FIG. 12 is a block diagram showing a partial configuration of a tracking servo sub-loop.

FIG. 13 is a block diagram showing an internal configuration of a speed / movement distance calculation circuit.

FIG. 14 is a timing chart of signals generated when detecting the rotation speed of the sled motor.

FIG. 15 is a diagram showing a positional relationship between an objective lens, a disk, and a light source.

FIG. 16 is a diagram illustrating a voltage value of a drive signal applied to a sled motor during a long search.

FIG. 17 is a diagram showing a relationship between a disk radial direction and a rotation speed in zone CLV control.

FIG. 18 is a diagram showing a relationship between a zone of a disk and an allowable rotation speed thereof.

FIG. 19 is a diagram showing control of the number of revolutions of a spindle motor when performing a search from the inner circumference side to the outer circumference side of the disk.

FIG. 20 is a diagram showing control of the number of revolutions of a spindle motor when performing a search from the outer peripheral side to the inner peripheral side of the disk.

FIG. 21 is a timing chart showing a relationship between output signals of respective units when power is turned on.

FIG. 22 is a timing chart showing a relationship between output signals of respective units when the disk is stopped.

FIG. 23 is a timing chart showing the relationship between output signals of the respective units when the disk starts rotating again after stopping rotation.

FIG. 24 is a timing chart showing the relationship between the output signals of the respective units when the disk starts rotating again after stopping rotation.

FIG. 25 is a diagram showing the relationship between each zone of the disk and the rotation speed.

[Explanation of symbols]

 Reference Signs List 1 disk 2 optical pickup 3 magnetic head 4 spindle motor 5 thread motor 6 RF processing circuit 7 AD converter 8 control microcomputer 9 signal processing circuit 10 digital servo processing circuit 11a, 11b Hall element 12 speed / movement distance calculation circuit 13 PWM signal generation Circuit 14 PWM driver 15 Spindle motor driver 16 Head motor 17 Head drive circuit 18 Head elevating drive circuit 19 Control circuit 20 Interface 21a, 21b Mirror area 22 TOC area 23 Main information area 24 Lead-out area 25 Spindle shaft fitting holes 26a, 26b Clock mark 27a, 27b Data part 28a, 28b Wobble 31 LD driver 32 Lead-in switch 41 Laser diode 42 First diffraction grating 43 Collimation Tarenzu 44 objective lens 45 PBS 46 Wollaston prism 47 a concave lens 48 first photodetector 49 second grating 50 second photodetector

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinori Kajiwara 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Yoshimasa Okada 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Hideo Yoshida 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka F-term (reference) 5D109 KA07 KB04 KB05 KD03 KD23 KD50 5D118 AA13 AA14 AA18 AA21 BA01 BB02 BF02 BF03 CA13 CA15 CA16 CC12 CC15 CD03 CD11 CF16 CF25 CG04 CG09 CG14 CG24 CG33 CG36 CG44 DA33 DA42 DB03 DB08 DB12 DC03

Claims (8)

[Claims] 1. An optical pickup for irradiating a laser beam to a disk serving as a data recording medium, an objective lens provided in the optical pickup and for converging the laser beam to a track of the disk, and an objective lens provided on the disk. An objective lens moving means for moving in a radial direction of the optical pickup; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; and a tracking error signal provided from the tracking error signal generating means. A tracking servo means for operating the objective lens moving means to make the objective lens follow a track of the disc; and a sled motor for moving the optical pickup in a radial direction of the disc at a high speed; Laser than pickup In a disk device for recording or reproducing data by irradiating a track on the disk with a beam, a speed signal generating means for detecting a rotation speed of the sled motor and generating a speed signal, the speed signal and the tracking error And a difference signal generating means for generating a difference signal representing the difference between the two signals, wherein the tracking servo means operates the objective lens moving means based on the tracking error signal. A disk drive for driving the sled motor based on the difference signal generated by the difference signal generating means, so that the objective lens follows a track of the disk. 2. An optical pickup for irradiating a disk as a data recording medium with a laser beam, an objective lens provided in the optical pickup and for converging the laser beam to a track of the disk, and an objective lens provided on the disk. An objective lens moving means for moving in a radial direction of the optical pickup; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; and a tracking error signal provided from the tracking error signal generating means. A tracking servo means for operating the objective lens moving means to make the objective lens follow a track of the disc; and a sled motor for moving the optical pickup in a radial direction of the disc at a high speed; Laser than pickup In a disk device for recording or reproducing data by irradiating a beam on a track of the disk, a speed signal generating means for detecting a rotation speed of the sled motor and generating a speed signal, and a light output by the optical pickup Shift signal generating means for generating a shift signal representing an amount of shift of the optical axis of the objective lens from the optical axis of the light source of the laser beam from the detection signal; and the speed signal and the shift signal. And a difference signal generating means for generating a difference signal representing a difference between the two signals, wherein the tracking servo means operates the objective lens moving means based on the tracking error signal, and the difference signal generating means By driving the sled motor based on the generated difference signal, A disk device, wherein an objective lens is made to follow a track of the disk. 3. The laser beam emitted from the optical pickup to the disk comprises a main beam focused on a read track and sub-beams focused on two tracks adjacent to both sides of the read track, respectively. A light detection signal obtained from the reflected light of the main beam and the two sub beams is given to the shift signal generating means from the optical pickup, and the shift signal generating means converts the light detection signal based on the reflected light of the main beam into a light detection signal. 3. The disk device according to claim 2, wherein a shift signal is generated by adding a sum signal of light detection signals by reflected light of the two sub beams. 4. The laser beam emitted from the optical pickup to the disc comprises a main beam focused on a read track and sub-beams focused on two tracks adjacent to both sides of the read track, respectively. A light detection signal obtained from the reflected light of the main beam and the two sub-beams is given from the optical pickup to the tracking error signal generating means, and the tracking error signal generating means detects light based on the reflected light of the main beam. 4. The disk drive according to claim 1, wherein a tracking error signal is generated by subtracting a sum signal of light detection signals by reflected light of the two sub beams from the signal. 5. An optical pickup for irradiating a disk as a data recording medium with a laser beam, an objective lens provided in the optical pickup and converging the laser beam on a track of the disk, and an objective lens for the disk. An objective lens moving means for moving in a radial direction of the optical pickup; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; and a tracking error signal provided from the tracking error signal generating means. A tracking servo means for operating the objective lens moving means to make the objective lens follow a track of the disc; and a sled motor for moving the optical pickup in a radial direction of the disc at a high speed; Laser than pickup In a disk device for recording or reproducing data by irradiating a beam on a track of the disk, a plurality of Hall elements for detecting a rotation speed of the sled motor, and a plurality of detection signals from the plurality of Hall elements, respectively. A differentiating means for differentiating, and a plurality of differential signals obtained by differentiating the plurality of detection signals by the differentiating means are respectively converted into absolute values, and positive or negative polarities are given according to the rotation direction of the thread motor. An absolute value means, an adding means for adding a plurality of signals output from the absolute value means, a signal from the adding means and the tracking error signal are given, and a difference between the two signals is represented. And a difference signal generating means for generating a difference signal. A disk operating the objective lens moving means and driving the sled motor based on the difference signal generated by the difference signal generating means to cause the objective lens to follow the track of the disk. apparatus. 6. An optical pickup for irradiating a disk as a data recording medium with a laser beam, an objective lens provided in the optical pickup and for converging the laser beam on a track of the disk, and an objective lens provided on the disk. An objective lens moving means for moving in a radial direction of the optical pickup; a tracking error signal generating means for generating a tracking error signal from a light detection signal output by the optical pickup; and a tracking error signal provided from the tracking error signal generating means. A tracking servo means for operating the objective lens moving means to make the objective lens follow a track of the disc; and a sled motor for moving the optical pickup in a radial direction of the disc at a high speed; Laser than pickup In a disk device for recording or reproducing data by irradiating a beam on a track of the disk, a shift amount of an optical axis of the objective lens from a light source optical axis of the laser beam based on a light detection signal output by the optical pickup. Shift signal generating means for generating a shift signal representing: a plurality of Hall elements for detecting a rotation speed of the sled motor; a plurality of differentiating means for differentiating a plurality of detection signals from the plurality of Hall elements, respectively; Absolute value converting means for respectively converting a plurality of differential signals obtained by differentiating a plurality of detection signals by the differentiating means into absolute values and giving a positive or negative polarity in accordance with a rotation direction of the sled motor; Adding means for adding a plurality of signals output from the value converting means; and receiving the signal from the adding means and the shift signal. And a difference signal generating means for generating a difference signal representing a difference between the two signals, wherein the tracking servo means operates the objective lens moving means based on the tracking error signal, and the difference signal A disk device, wherein the objective lens follows a track of the disk by driving the thread motor based on the difference signal generated by the generation unit. 7. The laser beam emitted from the optical pickup to the disk includes a main beam focused on a read track and sub-beams focused on two tracks adjacent to both sides of the read track, respectively. A light detection signal obtained from the reflected light of the main beam and the two sub beams is given to the shift signal generating means from the optical pickup, and the shift signal generating means converts the light detection signal based on the reflected light of the main beam into a light detection signal. 7. The disk device according to claim 6, wherein a shift signal is generated by adding a sum signal of light detection signals due to the reflected lights of the two sub beams. 8. The laser beam emitted from the optical pickup to the disk includes a main beam focused on a read track and sub-beams focused on two tracks adjacent to both sides of the read track, respectively. A light detection signal obtained from the reflected light of the main beam and the two sub-beams is given from the optical pickup to the tracking error signal generating means, and the tracking error signal generating means detects light based on the reflected light of the main beam. 8. The disk drive according to claim 5, wherein a tracking error signal is generated by subtracting a sum signal of light detection signals by reflected light of the two sub beams from the signal.