JP2711103B2 - Optical disc apparatus and eccentricity information writing control method - Google Patents

Description

[Contents] Outline Industrial application field Conventional technology (FIGS. 8 and 9) Problems to be Solved by the Invention Means for Solving the Problems (FIG. 1) Action Embodiment (A) Description of configuration of one embodiment (FIGS. 2 and 3) (b) Description of waveform storage section (FIGS. 4 and 5) (c) Description of operation of one embodiment (FIG. 6) (FIG. 7) (d) Description of Another Embodiment Effect of the Invention [Summary] In an optical disc apparatus that performs eccentricity correction control of a light beam of an optical head on a track of an optical disc using eccentricity information in a waveform storage unit, and then performs track following control. An optical disc apparatus and an eccentricity information writing control method for performing writing control for writing eccentricity information to a waveform storage unit, with the object of writing eccentricity information such that an average position of a position signal is at the center of a tracking range, Light beam on rotating optical disc An optical head that irradiates and receives light from the optical disk; a track servo control unit that creates a track error signal from a light reception signal of the optical head and controls a track following the light beam of the optical head; A position sensor for detecting movement in the track direction, and a waveform storage unit in which the output of the position sensor is written as eccentricity information, and the light beam is moved along the eccentricity by the eccentricity information of the waveform storage unit. From the above, in the optical disc apparatus in which the track following control is performed by the track servo control unit, the control unit determines whether the eccentricity information written in the waveform storage unit is deviated from the center of the following range of the light beam. In the case of deviation, after the light beam is track-jumped by the deviation amount via the track servo control unit, the output of the position sensor is stored in the waveform storage unit. I wrote it.

[Industrial applications]

The present invention relates to an optical disk device that performs write control for holding eccentricity information and an eccentricity information writing control method in an optical disk device that controls the optical head to track a light beam on a track of an optical disk.

An optical disk device can be read / written by a light beam, so that a track interval can be set to several microns, and is attracting attention as a large-capacity storage device.

In this optical disk device, track servo control is used to control the following of a light beam (spot light) on the track.

In the track servo control, a track error signal is obtained using diffraction of a guide groove (pre-group) of an optical disk medium, servo is applied, and a spot light is tracked (guide groove).
Is to follow.

An optical disk device is often used as a replaceable medium because recording / reproduction can be performed in a non-contact manner.

However, in the case of a replaceable medium, the eccentricity is inevitably increased, and the pull-in time of the track servo is prolonged.

[Conventional technology]

 FIG. 8 is an explanatory diagram of the track servo of the optical disk.

As shown in FIG. 8 (A), the optical disk device has a motor 1a.
With respect to the optical disk 1 which rotates around the rotation axis,
The optical head 2 is moved and positioned in the radial direction of the optical disk 1 by the head moving motor 6, and the optical head 2 reads (reproduces) / writes (records) the optical disk 1.

On the other hand, the optical head 2 guides the light emitted from the semiconductor laser 24 as a light source to the objective lens 20 via the lens 25a and the polarizing beam splitter 23, and narrows the beam spot (spot light) BS with the objective lens 20 to irradiate the optical disc 1 with the light. The optical disc 1 is configured so that the reflected light from the optical disc 1 is incident on the four-divided photodetector 26 via the objective lens 20 and from the polarizing beam splitter 23 via the lens 25b.

In such an optical disk device, the optical disk 1
A large number of tracks or pits are formed at intervals of several microns in the radial direction of the optical disk 1. Even a slight eccentricity causes a large positional deviation of the track, and the undulation of the optical disk 1 causes a focal position deviation of the beam spot. Must follow a beam spot of 1 micron or less.

For this purpose, a focus actuator (focus coil) 22 for changing the focal position by moving the objective lens 20 of the optical head 2 in the vertical direction in the figure, and moving the irradiation position in the track direction by moving the objective lens 20 in the horizontal direction in the figure. Is provided with a track actuator (track coil) 21 for changing the position.

In response to this, the focus servo control unit 4 that generates the focus error signal FES from the light receiving signal of the light receiver 26 and drives the focus actuator 22 and the light receiver 26
The track servo control unit 3 that generates a track error signal TES from the received light signal and drives the track actuator 21 is provided.

The principle of the track servo control utilizes a diffraction phenomenon of the beam spot BS by a spiral guide groove (track) 10 provided in advance on the optical disc 1, as shown in FIG. 8 (B).

That is, by utilizing the fact that the distribution of the amount of reflected light in the light receiver 26 changes due to the diffraction of light by the track 10 depending on the position of the beam spot BS with respect to the track 10,
The position error of the beam spot with respect to 10 is obtained.

For example, when the push-pull method using the four-divided photodetectors 26a, 26b, 26c, and 26d is used for the photodetector 26, the distribution of the amount of reflected light in the photodetector 26 is as shown in FIG. If there in the positional relationship as in P _1, FIG. 8 (D), when to track 10 where the beam spot is P (when the on-track), the FIG. 8 (E), the track 10 If the beam spot against is in the P ₂ becomes view the 8 (F).

Therefore, in the track servo control unit 3, the light receivers 26a to 26d
{(A + b)-(c + d)} is obtained from the outputs a to d, the track error signal TES shown in FIG. 8 (G) is obtained.
Accordingly, if the track actuator 21 is driven and the objective lens 20 is driven in the left and right direction, the beam spot can be controlled to follow the track 10 of the optical disc 1 regardless of the eccentricity of the optical disc 1.

In such track servo control, after the optical head 2 is moved by the motor 6 which is a coarse access mechanism, and the light beam is positioned near the target track (within about 100 tracks), the track servo control is turned on and accurate. Perform accurate positioning.

Therefore, the track servo control is turned off at the time of coarse access by the motor 6, and the track servo control is turned on after the coarse access is completed. Therefore, if the optical disc 1 has a large eccentricity, the track traverse speed becomes large at the start of the track servo. Thus, the time from the start to the end (pull-in time) is lengthened, and the access speed is reduced.

For this reason, a track access control technique employing eccentricity correction control as shown in FIG. 9A has been proposed.
(For example, see pages 73 to 74 of the magazine "Nikkei Mechanical", July 13, 1987).

In this eccentricity correction control, in addition to the configuration of FIG.
A waveform storage unit 7 is provided, and track position fluctuations are measured by the optical head 2 immediately after turning on the power or immediately after exchanging the optical disk.
The information is stored as a table in the waveform storage unit 7 as the eccentricity information.

Then, the eccentricity information is read from the waveform storage unit 7 at the time of the access operation, and the motor 6 is driven in addition to the position command of the motor 6.

When such eccentricity correction control is performed, the light beam is moved eccentrically to follow the track, and the track traversing speed is reduced to the tracking accuracy. Then, the track servo control can be started, and the track pull-in time can be greatly reduced.

[Problems to be solved by the invention]

To perform the eccentricity correction control, the track servo control unit 3 is operated (in the track servo ON state), the light beam follows the track, and the movement of the light beam is detected as a position signal to obtain eccentricity information. Need to be written to the waveform storage unit 7.

At this time, which track the light beam is drawn into
Unknown.

Therefore, as shown in FIG. 9 (B), when the track servo is pulled in at point a, the position signal becomes like TPSa, and when the track servo is pulled in at point b, it becomes like the position signal TPSb. Signal when is at the center of the tracking range
It will deviate from TPSr.

Such a displaced position signal can also be used as eccentricity information. However, when this eccentricity information is written in the waveform storage unit 7 and reproduced to pull in the track servo, the position of the light beam which is deviated from the center of the following range is inevitable. Drawn into.

Since the following range of the light beam has a constant width on the plus (or outer) side and the minus (or inner) side around the following range, deviation of the drawing center means that the following range of the light beam after the drawing becomes smaller. There has been a problem that the displacement is changed due to the displacement, and particularly the outer side and the inner side are different.

For this reason, the eccentricity correction control changes the range of the lens seek operation for seeking the target track by the light beam, which causes the lens seek performance to deteriorate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disk device capable of writing eccentricity information such that an average position of a position signal is at the center of a tracking range, and an eccentricity information writing control method therefor.

[Means for solving the problem]

 FIG. 1 is a diagram illustrating the principle of the present invention.

In the figure, the same components as those shown in FIGS. 8 and 9 are denoted by the same symbols.

According to the present invention, the control unit 5 reads out and checks the eccentricity information written in the waveform storage unit 7 to determine a deviation from the center of the following range. The output of the position sensor 29 is written into the waveform storage unit 7 after the beam is track-jumped by the deviation amount.

[Action]

In the present invention, as shown in FIG. 1 (B), the eccentricity information once written in the waveform storage unit 7 is reproduced to check the deviation. If the amount of eccentricity is not D, it is in the range of ± D / 2.

In order to eliminate this shift, the shift spectral beam is track-jumped.

Then, the output of the position sensor 29 is written into the waveform storage unit 7 again as eccentricity information.

By repeating this, eccentricity information TPSr having the center of the position at the center of the tracking range is obtained, and this can be set in the waveform storage unit 7.

Therefore, since the eccentricity correction control is performed at the center of the tracking range based on the reproduced eccentricity information, the track pull-in can also be performed at the center of the tracking range, and the tracking range can be prevented from changing.

Although the eccentricity information is input to the track servo control unit 3 and the eccentricity correction control is performed by driving the track actuator 3, the moving unit 6 may be driven by the eccentricity information.

〔Example〕

(A) Description of configuration of one embodiment FIG. 2 is a block diagram of one embodiment of the present invention, and FIG.
It is a block diagram of the optical head of a figure structure.

In the figure, the same components as those shown in FIGS. 1, 8 and 9 are denoted by the same symbols.

First, the configuration of the optical head will be described with reference to FIG.

In FIG. 3A, the light of the semiconductor laser 24 is collimated by a collimator lens 25a,
To the objective lens 20, and is narrowed down to the beam spot BS. The reflected light from the optical disc 1 is an objective lens
20, the light enters the polarization beam splitter 23, and from the condenser lens 27 enters the four-division light receiver 26.

The objective lens 20 is provided at one end of an actuator body 28 rotatable about a rotation axis 28a, and has a fixed slit 28b at the other end.

The actuator body 28 is provided with a coil portion 28c, a focus coil 22 is provided around the coil portion 28c, a spiral track coil 21 is provided on a side surface, and a magnet 28d is provided around the coil portion 28c. I have.

Therefore, when a current is applied to the focus coil 22, the actuator 28 equipped with the objective lens 20 moves up or down in the X-axis direction in the drawing similarly to the voice coil motor, whereby the focus position can be changed. When a current is supplied, the actuator 28 rotates in the α direction about the rotation axis 28a, thereby changing the position in the track direction.

Fixed slit 28 provided at the end of actuator 28
For b, position sensors 27 and 29 are provided. As shown in FIGS. 3B and 3C, the position sensors 27 and 29 are 29a to 29d are provided to face each other via the fixed slit 28b.

A window W is provided in the fixed slit 28b, and the light emitting section 2
The light 7 is received by the four-divided light receivers 29a to 29d via the window W.

For this reason, as shown in FIG.
Quadrant photodetectors 29a to 29d according to the amount of movement in the α and X directions of 28
Changes in the received light distribution. Therefore, similarly to the focus and track servos, the position signal TPS in the track direction and the position signal FPS in the focus direction are obtained from the outputs A, B, C, and D of the light receivers 29a to 29d as follows.

TPS = (A + C)-(B + D) FPS = (A + B)-(C + D) These position signals TPS and FPS become zero at the center position with respect to the deviation from the center position C as shown in FIG. 3 (C). S
, And an electrical spring force in the direction of the center position can be applied using this signal.

 Next, the configuration of FIG. 2 will be described.

Reference numeral 5 denotes the above-described control unit, which is constituted by a microprocessor and executes track access and eccentricity information writing control in accordance with the processing flow of FIG.
S, track zero cross signal TZC, off-track signal TO
S, receives the reproduction eccentricity information TPS ', and controls by issuing a servo-on signal SVS, a lock-on signal LKS, a storage / reproduction mode signal WRM, an eccentricity-on signal HFS, and a track jump signal TJS.

7a is an eccentric switch, which is a control unit (hereinafter referred to as MPU)
5 is turned on by the eccentric on signal HFS of 5, and outputs the reproduced eccentricity signal (information) of the waveform storage unit 7 to the track servo control unit 3.

Reference numeral 8 denotes a head circuit, which is the outputs a to
d, an RF generating circuit 80 for generating an RF signal RFS, an amplifier 8 for amplifying the outputs a to d of the four-segmented light receiver 26 and outputting servo outputs SVa to SVd, and a four-segmented light receiver 29a for the position sensor 29. Two
And a TP creation circuit 82 for creating a track position signal TPS from the outputs A to D of 9d.

Reference numeral 30 denotes a TES generation circuit, which is a servo output SVa of the amplifier 81.
A circuit for generating a track error signal TES from SVd, 31 is an all signal generation circuit, which adds all the servo outputs SVa to SVd to generate an all signal DSC which is an all-reverse level, 32 is an AGC
(Automatic Gain Control) circuit that divides the track error signal TES by the total signal (total reflection level) DCS, and performs AGC with the total reflection level as a reference value, and corrects fluctuations in irradiation beam intensity and reflectance. 33 is a phase compensation circuit, which is a track error signal TES given a gain.
Is differentiated and added to the proportion of the track error signal TES to advance the high-frequency phase.

34a is a zero cross detector, which has a track error signal T
A detector for detecting a zero crossing point of ES and outputting a track zero crossing signal TZC to the MPU 5, 34b is an off-track detecting circuit, and the track error signal TES has a constant value V _{0 in the} plus direction.
The off-track signal TOS is output to the MPU 5 upon detection of the above-mentioned condition and the fact that the value has become equal to or less than the fixed value −V _{0 in the} negative direction, that is, the off-track state.

Reference numeral 35 denotes a servo switch, which is a servo-on signal SV of MPU5.
Closed when S turns on, closes the servo loop, opens when off, opens the servo loop, 36 is a return signal creation circuit,
A lock-on switch 37 for generating a return signal RPS toward the center position of the actuator 28 in FIG. 3C from the track position signal TPS from the TP generation circuit 82, and a lock-on switch 37 for turning on the lock-on signal LKS of the MPU 5 Close, lead the return signal RPS to the servo loop, open it off, cut the introduction of the return signal RPS to the servo loop, 38 is a track jump voltage generation circuit, plus (outer) direction from the MPU5 or minus ( A track jump voltage in the plus or minus direction is output by the track jump signal TJS in the inner direction.

39a is an inverting amplifier, which is the sum of the output of the servo switch 36 and the output of the lock-on switch 38 and the eccentric switch 7a.
A power amplifier 39 amplifies the output of the inverting amplifier 39a and supplies the track drive current TDV to the track actuator 21.

(B) Description of the waveform storage unit FIG. 4 is a block diagram of the waveform storage unit according to one embodiment of the present invention, and FIG.
FIG. 7 is an explanatory diagram of the operation of the waveform storage unit according to one embodiment of the present invention.

In FIG. 4, the same components as those shown in FIGS. 1 and 2 have the same reference numerals, 70 is a memory, and a 14-bit address.
Addressed by A0 to A13, 1 by write enable signal WE
A bit input data DIN is written and storage data is output from an output terminal DO, 73 is an address generation unit,
14-bit address A0 to 16 kilobit memory 70
A13, an address clock ACL is used as an input clock, a lower address counter 73a for generating lower 4-bit addresses A0 to A3, a highest-order output A3 of the address counter 3a as a clock, and a higher-order 10-bit address A4.
To A13.

A filter unit 74 generates a voltage in accordance with the output DO of the memory 70, integrates the generated voltage to output high-frequency components, and outputs reproduced eccentricity information TPS ′. resistance r ₁ and a capacitor C which constitutes the vessel
When, the output resistance r _2, and a amplification amplifier AMP, a memory 7
Regarding the output DO of 0 as the voltage source, if DO = "1", (5 + A)
V, if DO = "0" (5- A) V (A is determined. From r _2, r ₃₎ in which to generate, to create a reproduction eccentricity information TPS 'in the integration operation.

A comparator (comparison amplifier) 75 compares the reproduction eccentricity information TPS 'from the track position signal TPS, and TPS>TPS'
If TPS≤TPS ', write data "1" is generated.

76 is a clock generator, which has a crystal oscillator,
A memory controller which generates a clock CL shown in FIG. 77 is an address count clock ACL derived from the clock CL.
And generates a chip select signal CS or a write enable signal WE according to the mode signal WRM from the MPU 5.

The memory control unit 77 is composed of a quinary counter that counts the clock CL, and generates the address clock ACL shown in FIG. 5A from the QB terminal and the timing clock TCL shown in FIG. 5A from the RCO terminal. Since the counter 770 and the write enable signal WE are generated when the mode signal WRM is “0” (instruction of the storage mode), the OR gate 771 for taking the OR between the mode signal WRM and the timing clock, the inverter 772, and the chip select signal CS Since this occurs when the mode signal WRM is "1" (playback mode instruction), the AND between the mode signal WRM and the timing clock TCL is inverted and output.
In order to operate the AND gate 773 and the synchronous counter 770 as a quinary counter, the inverter 774 inverts the timing clock TCL and inputs it to the load terminal of the counter 770.
Having.

Reference numeral 11 denotes a motor synchronization control unit which controls the spindle motor 1a at a constant speed by synchronizing the speed and phase with the position signal of the spindle motor 1a and the clock CL. Reference numeral 12 denotes a motor driver, which is an output of the motor synchronization control unit 11. With spindle motor
1a.

Next, the waveform storage / reproduction operation will be described with reference to FIG.

The clock CL of the clock generator 76 is input to the synchronization counter 770 of the memory controller 77.

The synchronous counter 770 divides the clock CL by 5 and generates an address clock ACL from a QB terminal and a timing clock TCL from an RCO terminal.

The address clock ACL is input to the lower counter 73a,
The counter 73a performs a coefficient operation at the falling edge of the address clock ACL to update the address.

On the other hand, the timing clock TCL is the address clock A
It is generated when one clock is delayed from the center of the CL cycle.

Therefore, the write enable signal WE and the chip select signal
Since CS is generated during one address period, the output data DO of the corresponding address of the memory 70 is divided by the chip select signal CS and the write enable signal WE as shown in FIG.

Next, as shown in FIG. 5B, a sine wave input position signal
When TPS is input, the memory 70 is all "0".
The initial value of the reproduction output TPS 'of the filter unit 74 is "0".

If the input TPS is larger than the output TPS ', the comparison amplifier 75 gives "1" to the memory 70 as write data if the input TPS is larger than the output TPS'.

In the storage mode, the MPU 5 sets the mode signal WRM to “0”, and applies the write enable signal WE shown in FIGS. 5A and 5B to the memory 70 from the inverter 772.

The memory 70 writes the write data of the comparison amplifier 75 at the address position indicated by the address generation unit 73 every time the write enable signal WE is input.

For example, if the write data is “1” while the address al + 1 is given to the memory 70, the storage data Dl + 1 of the address changes from “0” to “1” by the write enable signal.

Therefore, the output DO of the memory 70 also changes from “0” to “1”.

That is, when "1" is stored in the memory 70, the filter means
The output TPS 'through 74 has a higher voltage level than the previous state; conversely, if "0" is stored, the output TPS' has a lower voltage level than the previous state.

Therefore, as shown in FIG.
Since S ′ is smaller than the input TPS, the output of the comparison amplifier 75 is “1”
Is written into the memory 70 by the write enable signal WE, so that the level of the output TPS 'rises.

As a result, the output TPS 'follows the level of the input TPS.

Since the address of the memory 70 changes every moment as described above, the waveform of the input TPS is stored in the memory 70 and output as the output TPS '.

That is, the write data Din as shown in FIG. 5 (B) corresponds to the input TPS, and the reproduced output TPS 'of the filter unit 74 follows the input TPS by the output DO.

This means that the analog waveform is delta-modulated and stored.

In the figure, the output TPS 'is shown roughly for the sake of understanding the operation. However, in practice, approximately 16000 samples are sampled for one cycle of the input TPS, so that the signal is a smooth signal closer to the input TPS.

The clock CL of the clock generator 76 is the spindle motor 1a.
Therefore, the eccentric waveform is stored in the memory 70 for one cycle (for one rotation) in synchronization with the rotation of the optical disk 1.

On the other hand, in reproduction, the mode signal WRM becomes "1" and the chip select signal CS is given from the NOT AND gate, so that the stored write data is output from the output DO in the same manner as in FIG. The unit 74 outputs the reproduced waveform TPS '.

At this time, since the write enable signal WE is not issued,
No writing is performed.

Such a waveform storage unit 7 can store / reproduce an analog waveform without using an A / D and D / A converter, can be realized by an inexpensive comparison amplifier and a filter, and can significantly reduce the price. Intervention is minimal and more economical.

(C) Description of Operation of One Embodiment FIG. 6 is a flowchart of access processing of one embodiment of the present invention, and FIG. 7 is an explanatory diagram of the operation of one embodiment of the present invention.

After turning on the power and replacing the optical disk, the MPU 5 turns on the track servo control.

That is, the servo ON signal SVS is set to “1”, and the servo switch 35 is closed to form a servo loop of the track error signal TES.

On the other hand, both the lock-on signal LKS and the eccentric on signal HFS are “0”
The lock-on switch 37 and the eccentric switch 7a are kept off.

Accordingly, servo pull-in is started, and servo pull-in is performed so that the light beam BS follows the track.

If the MPU 5 determines that the off-track signal TOS is not generated for a certain period of time and the track zero-cross signal TZC has not been inverted for a certain period of time, it determines that the servo pull-in is completed.

In this state, the light beam BS is moving following the track by the track actuator 21, and the track position signal TPS by the output of the position sensor 29 shows a waveform according to the track actuator 21, that is, the light beam following operation. ing.

 That is, an eccentric waveform of the optical disk is output.

Then, as will be described later with reference to FIG. 6B, the eccentricity information is written into the memory 70 of the waveform storage unit 7, the MPU 5 confirms the written eccentricity information, and controls writing of the eccentricity information without deviation.

When the writing of the eccentricity information is completed, the MPU5
The WRM is returned from “1” to “0” and the reproduction mode is instructed to the waveform storage unit 7.

The waveform storage unit 7 stores the track position signal TP for exactly one rotation.
S is stored.

At this time, the mode signal WRM is set to “1” and the waveform storage unit 7
Output the reproduced waveform TPS ', the eccentric switch 7a remains off, so that no eccentric waveform is injected into the track servo controller 3.

Therefore, the light beam is still performing the track following operation by the track servo.

 The MPU 5 waits for a seek instruction from a higher order.

When a seek command from a higher order arrives at the MPU 5, the MPU 5 turns off the track servo for movement.

Therefore, the MPU 5 sets the servo-on signal SVS to “0”,
The servo switch 35 is turned off to release the track servo loop, and the lock on signal LKS and the eccentric on signal HFS are set to "1".

Therefore, the lock-on switch 37 is turned on, and the eccentric switch 7a is also turned on.

Therefore, a feedback loop is formed using the reproduction eccentricity information TPS 'of the waveform storage unit 7 as a command and the track position signal TPS as a feedback signal, and the actuator 28 of the optical head 2 is eccentrically driven by the track coil 21 to store the light beam BS. It moves in the track direction according to the eccentric waveform.

Then, in this state, the MPU 5 drives the moving unit (step motor) 6 to position the number of steps up to the target track, and moves the optical head 2 to the target track.

The MPU 5 turns on the track servo after the driving of the step motor 6 is completed.

Therefore, the MPU 5 turns on the servo-on signal SVS,
Close the servo switch 35 and start servo pull-in.

That is, the track error signal TES generated by the TES generation circuit 30 and controlled by the AGC circuit 32 to which the gain is applied.
Is phase compensated by the phase compensation circuit 34, and the servo switch 35
Then, the signal enters the inverting amplifier 39a, and a servo loop of the track error signal TES is formed.

At the same time, the MPU 5 sets the lock-on signal LKS and the eccentric on signal HFS to “0”, and turns off the lock-on switch 37 and the eccentric switch 7a.

Therefore, the return control signal RPS and the eccentricity signal TPS 'are not input to the inverting amplifier 39a.

This means that the eccentricity correction control of the light beam is performed immediately before the servo-on, so that the frequency of the track error signal TES after the movement of the optical head 2 becomes low, and the servo is turned on in that state, so that servo pull-in is easily performed. .

That is, the servo pull-in can be started in a state where the frequency of the track error signal TES is low, and the servo pull-in time is short.

After that, when MPU5 receives the read or write command,
Execute read / write and return to step.

In this way, the actuator can be moved along the eccentricity of the optical disk 1 even when the track servo is off, and the relative speed with respect to the track is reduced. In this state, the track servo is turned on and the track servo pull-in can be realized in a short time. .

Moreover, the configuration of the waveform storage unit for this can be simplified,
In addition, an inexpensive step motor such as a step motor can be used for the moving unit 6 and can be realized at low cost.

Next, the writing control of the eccentricity information will be described with reference to FIGS. 6 (B) and 7.

The MPU 5 sets the mode signal WRM to “1”, and
Of the storage mode is instructed to the memory control unit 77 of.

Accordingly, the write enable signal WE is output from the memory control unit 77.
Occurs, and as shown in FIGS. 4 and 5, the track position signal TPS by the position sensor 29 is written into the memory 70 as eccentricity information.

When the time corresponding to one rotation of the optical disk 1 has elapsed, the MPU 5 sets the mode signal WRM to “0” and instructs the memory control unit 77 on the reproduction mode.

Therefore, generation of the write enable signal WE is prohibited,
Since the chip select signal CS is generated, the memory 70 is read without writing.

 Then, the MPU 5 turns off the track servo.

That is, the servo-on signal SVS is turned off, and the servo switch 3
5 is opened and the track following control by the track error signal TES is stopped.

At the same time, the eccentric on signal HFS is kept off, the eccentric switch 7a is opened, and the reproduced eccentric signal
The input of S 'to the inverting amplifier 39a is not permitted.

Further, the lock-on signal LKS is turned on, the lock-on switch 37 is closed, and the return signal RPS is input to the inverting amplifier 39a.

Accordingly, the track actuator 21 is driven by the track position signal TPS, whereby the track actuator 21 is locked at the center position.

At this time, the memory 70 outputs the reproduction eccentricity information TPS 'from the filter unit 74 in the reproduction mode as shown in FIG. 5, and the waveform thereof varies between TPSa and TPSb as shown in FIG. It is in.

On the other hand, the track position signal TPS input to the comparison amplifier 75 is at the level of the center position (for example, OV) because the track actuator 21 is locked at the center position.

Therefore, the comparison amplifier 75 produces comparison outputs Dia, Dib, and Dir as shown in FIG. 7B obtained by slicing the reproduced eccentric waveform TPS 'at the center position level.

The MPU 5 receives the comparison output of the comparison amplifier 75 and measures the duty of one cycle.

That is, the MPU 5 outputs the comparison output at a predetermined cycle to the optical disc 1.
Is sampled for one rotation, the period when the comparison output is "1" and the period when it is "0" are counted, and the ratio (duty) is obtained.

For example, if there is a shift in the outer direction like TPSa in FIG. 7 (A), the comparison output Dia in FIG. 7 (B) is obtained.
If it is shifted in the inner direction like TPSb, the comparison output Dib shown in FIG. 7B is obtained, so that the period of “0” is almost the same and the duty is about 0%.

If there is almost no deviation, the reproduced eccentric waveform TPSr shown in FIG. 7A is obtained, the comparison output becomes Dir shown in FIG. 7B, and the duty is about 50%.

By this duty, MPU5 is too inner,
Judge whether the outer is too much.

For this reason, a certain margin width α (± 10%) is provided and MPU5
Checks whether the calculated duty is within the range of 50% ± α.

If it is less than (50% -α%), it is too inner, (50% + α
%) Or more, it is determined that there is too much outerwear.

If the MPU 5 determines that there is too much inner or too much outer, the MPU 5 calculates the amount of deviation from the center from the aforementioned duty.

For example, if the eccentricity is D, + D at 100% duty
That is, the shift is -D / 2 at / 2, duty 0%. The eccentricity D is calculated by the MPU 5 counting the number of inversions of the zero cross signal TZC for one rotation of the optical disc 1.

When the shift amount β is calculated in this manner, the MPU 5 turns on the eccentric on signal HFS and the lock on signal LKS, and turns on the eccentric switch 7a and the lock on switch 37.

Therefore, as described in the step of FIG. 6A, the light beam moves according to the eccentric waveform.

Next, the MPU 5 turns on the servo-on signal SVS, closes the servo switch 35, forms a servo loop of the track error signal TES, turns off the lock-on signal LKS, and turns off the lock-on switch 37.

Therefore, the movement of the light beam is controlled by the eccentric waveform storage unit TPS 'and the track error signal TES, and the track servo is performed.

When the track servo pull-in is completed, the MPU 5 instructs the track jump voltage generation circuit 38 to generate a track jump voltage by using the track jump signal TJS.

For this reason, the track jump voltage is given to the inverting amplifier 39a, and the track actuator 21 is driven to cause the light beam to track-jump by the amount of deviation, thereby performing lens seek.

Further, the MPU 5 turns off the eccentric on signal HES, turns off the eccentric switch 7a, and returns to the step for writing the eccentric waveform.

In this way, when the MPU 5 determines in step that the amount of deviation from the center is within the margin, the write control ends.

In this way, the actual track position signal TPS
In obtaining the eccentricity information from the eccentricity information, the eccentricity information written in the memory 70 is reproduced, the MPU 5 checks the duty, detects the amount of deviation, makes the light beam track jump by the amount of deviation, and obtains the eccentricity information without deviation Control to get.

In this embodiment, the lock-on signal LKS is turned on, and the output of the comparison amplifier 75 of the waveform storage unit 7 is used.
Since the displacement can be detected, the displacement can be easily detected.

(D) Description of Another Embodiment In the above-described embodiment, the waveform storage unit 7 has been described with reference to FIG. 4, but may have another known configuration.

Further, although the track actuator 21 is driven by the eccentric waveform, if a servo motor is used for the moving unit 6, such a motor may be driven, and the deviation amount may be detected by another method.

Further, since the eccentric waveform is a sine wave, it is not necessary to store the data for one rotation, but it is possible to store the data for a half rotation and use the inverted signal for the remaining half rotation.

In addition, a description has been given of the reflection type optical disk device, but the invention may be applied to a transmission type. The light receiver 26 has also been described as an example of the four-segment light receiver. The obtained light receiver can be used, and the generation of the track error signal is not limited to the push-pull method.

Although the present invention has been described with reference to the embodiments, the present invention can be variously modified in accordance with the gist of the present invention, and these are not excluded from the present invention.

〔The invention's effect〕

According to the present invention, as the eccentric waveform for the eccentricity correction control, there is an effect that a signal whose center is the center of the tracking range can be written, and the tracking range fluctuates even when the eccentricity correction control is performed. Therefore, it is possible to prevent the following performance from deteriorating.

[Brief description of the drawings]

 FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a structural diagram of an optical head having the structure shown in FIG. 2, and FIG. FIG. 5 is an explanatory diagram of the operation of the waveform storage unit having the configuration of FIG. 4, FIG. 6 is a processing flowchart of an embodiment of the present invention, FIG. 7 is an operational explanatory diagram of an embodiment of the present invention, FIG. 8 is an explanatory diagram of a track servo of an optical disk, and FIG. 9 is an explanatory diagram of a conventional technique. In the figure, 1 ... optical disk, 2 ... optical head, 3 ... track servo control unit, 5 ... control unit, 7 ... waveform storage unit, 29 ... position sensor.

Claims (2)

(57) [Claims] An optical head (2) for irradiating a rotating optical disk (1) with a light beam and receiving light from the optical disk (1); and a track error based on a light receiving signal of the optical head (2). A track servo control unit (3) for creating a signal and controlling the track following of the light beam of the optical head (2); and the optical head (2) when the track following control function is operated for one track. Is calculated between the center of the amplitude of the waveform formed by the trajectory of the radial movement of the optical head and the center of the followable range of the optical head (2), and the amount of shift is calculated according to the amount of shift. An optical disk device comprising: a control unit (5) that selects a new track that becomes smaller and uses the waveform of the new track as eccentricity information. 2. An optical head (2) for irradiating a rotating optical disk (1) with a light beam and receiving light from the optical disk (1), and a track error based on a light receiving signal of the optical head (2). A track servo control unit (3) for generating a signal and controlling the track following of the light beam of the optical head (2), wherein the control unit (5) operates when one track following control function operates. It is determined whether or not the center of the amplitude of the waveform formed by the trajectory of the radial movement of the optical head (2) and the center of the followable range of the optical head (2) are shifted. Eccentricity information of an optical disc apparatus, wherein the beam is track-jumped by the deviation amount via a track servo control unit (3), and the movement of the light beam in the track direction is held as eccentricity information. Write control method.