JPH10228648A - Focus jump control method and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device equipped with a focus jump control means for moving a light spot to another recording surface at high speed with accuracy by reducing an effect of disturbance upon an optical disk having plurality of recording surfaces, such as a wobble or gravity of the optical disk. SOLUTION: When a focus jump is performed, a switch 10 is connected with a detecting gain amplifier 16 by a mode discriminator 22, and a target value of a position to be moved is generated by a target value generator 17, and this target value is compared with an estimated value outputted from a focus actuator model 15 by an adder 19 to output an error differing from the target value. This error differing from the targer value is amplified and outputted via the switch 10 to a compensator 11 by the detecting gain amplifier 16. A drive command Vs is outputted by the compensator 11. The drive command Vs of the compensator 11 is amplified by an amplifier 12 and is impressed upon a focus actuator 7 to drive and jump an objective lens 5, so as to make a focusing position of the light spot follow up the target value of the target generator 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc apparatus for recording or reproducing information, and more particularly to an optical disc having a plurality of information recording surfaces on a disc-shaped optical disc.
The present invention relates to a focus jump control method for moving a light spot to a desired recording surface at a high speed and an optical disc device.

[0002]

2. Description of the Related Art In an optical disk apparatus for optically recording / reproducing information on a disk-shaped recording medium, the following method has been generally adopted as a method for focusing a light spot on a recording surface. I was When the optical disk is inserted into the optical disk device, the lens is moved in the vertical direction with a predetermined driving force without rotating the optical disk, and an error from the recording surface is determined by a focus error signal indicating a deviation of the light spot from the focal position. This is a method of detecting and pulling the focus position based on a change in the focus error signal.

[0003] This method is based on the premise that one optical disk has only a single recording surface, and once focusing is performed without rotating the optical disk, the pull-in operation is not required again until the optical disk is replaced. That's the way it is done.

As a technique for moving the focal position of the light spot during rotation of the optical disk, a track jump operation of moving the light spot in the radial direction of the optical disk between adjacent tracks is known.

The conventional track jump method uses a tracking error signal for detecting a deviation of a light spot from the track center, as disclosed in Japanese Patent Application Laid-Open No. 52-26802, for example. The tracking error signal is set to 0
This is a method of switching between acceleration and deceleration at the time of crossing.

[0006]

However, in the conventional general method of focusing a light spot on a recording surface when an optical disk is inserted, an optical disk having a plurality of recording surfaces on one optical disk is rotated. In the meantime, a focus jump method for quickly and stably moving the focus of a light spot to a different recording surface in a direction perpendicular to the optical disk surface has not been considered.

For this reason, even if a constant driving force is applied to move to a different recording surface during rotation of the optical disk,
When the optical disk rotates during the jump and the position of the recording surface changes due to the rotation of the optical disk, it is conceivable that the optical disk cannot jump to the recording surface to be moved.

The method described in Japanese Patent Laid-Open No. 52-26802 is based on the premise that error signals are continuous. If there is a section in which the error signal is 0 without a sinusoidal change, the direction to jump cannot be specified. Therefore, this conventional method is directly applied to the focus jump of an optical disk having a plurality of recording surfaces. I couldn't do that.

Further, when moving in the focus direction, the direction in which gravity acts varies depending on how the optical disk device is placed, for example, vertically or horizontally, and the external force applied differs. Further, in an in-vehicle or portable optical disk device, the applied external force changes every moment. For this reason, it is necessary to correct an external force such as gravity immediately before jumping, but no consideration has been given to this point in the past.

In the case where the optical disk surface deflection synchronized with the rotation of the optical disk caused by the manufacturing accuracy of the optical disk or the accuracy of chucking the optical disk is large, jumping cannot be performed stably.

SUMMARY OF THE INVENTION An object of the present invention is to provide a focus jump control for moving an optical spot to another recording surface at high speed and accurately without being affected by disturbances such as gravity or optical disk surface deflection in an optical disk having a plurality of recording surfaces. Is to provide a way.

Another object of the present invention is to focus on an optical disk having a plurality of recording surfaces, in which a light spot is moved at high speed and accurately to another recording surface without being affected by disturbances such as gravity or optical disk surface deflection. An object of the present invention is to provide an optical disk device provided with jump control means.

[0013]

In order to achieve the above object, the present invention provides an objective lens for irradiating any one of a plurality of recording surfaces of a rotating optical recording medium with a light spot and a plurality of objective lenses for irradiating the objective lens with a plurality of recording surfaces. A focus actuator for moving the optical spot in a direction perpendicular to the surface, and positioning the optical spot on any of the information tracks on the plurality of recording surfaces to record or reproduce information. In a focus jump control method for moving a position, a drive signal of a focus actuator is delayed by one rotation time of an optical disc, and a recording surface and an optical signal are delayed based on a drive signal delayed by a focus actuator model having characteristics equivalent to the focus actuator. Estimate the relative position of the spot to the focus position, and perform real-time focus activation. It proposes a focus jump control method for generating a drive signal to jump the focusing position of the light spot on different recording surfaces in accordance with the error between the estimated relative position between the target position of the eta.

According to another aspect of the present invention, a drive signal for a focus actuator is delayed by one rotation of an optical disk, and a predetermined drive signal is added to the delayed drive signal to achieve different recording. A focus jump control method for generating a drive signal for jumping a focal position of a light spot to a surface is proposed.

According to another aspect of the present invention, there is provided an objective lens for irradiating any one of a plurality of recording surfaces of a rotating optical recording medium with a light spot, and the objective lens perpendicular to the plurality of recording surfaces. And a focus actuator for moving the focus actuator in one of the plurality of recording surfaces to record or reproduce information by positioning a light spot on the information track. Means for sequentially storing data, a focus actuator model for estimating the relative position between the recording surface and the focal position of the light spot based on a delayed drive signal having characteristics equivalent to the focus actuator, and a target for the focus actuator in real time. A target value generating means for outputting the position, and a phase estimated as the real-time target position. Suggest equipped optical disk device and means for generating a drive signal to jump the focusing position of the light spot on different recording surfaces according to the error between the position.

According to another aspect of the present invention, there is provided a means for detecting a rotational position of an optical disk, and a drive signal for a focus actuator corresponding to the detected rotational position of the optical disk. Means for successively storing data with a time delay, a focus actuator model for estimating a relative position between a recording surface and a focal position of a light spot based on a delayed drive signal having characteristics equivalent to a focus actuator, and a focus actuator. Target value generating means for outputting a target position in time, and means for generating a drive signal for jumping the focal position of the light spot to a different recording surface according to an error between the real time target position and the estimated relative position. An optical disk device provided with the same.

In order to achieve the above and other objects, the present invention further comprises means for sequentially storing a drive signal of a focus actuator with a time delay of one rotation of an optical disk, and a drive signal predetermined for the delayed drive signal. And a means for generating a drive signal for jumping the focal position of the light spot to a different recording surface by adding.

A storage means for storing the delayed drive signal, a focus actuator model, a target value generation means,
The jump drive signal generation means can be integrated as one control semiconductor element. Further, the storage means for storing the delayed drive signal and the predetermined jump drive signal generating means may be integrated as one control semiconductor element.

In the present invention, a position during a focus jump is estimated using a focus actuator model based on a drive signal one rotation before the optical disk, and the drive signal at the present time is compared with the estimated position, and an error signal is obtained. In addition, since the objective lens is controlled, the focus jump can be stably performed irrespective of an external force such as gravity and a disturbance such as surface deflection of the optical disk.

Further, since the drive signal before one rotation of the optical disk can be taken out based on the information on the rotation position of the optical disk, the area for storing the drive signal can be small. In this case, even if there is a higher-order vibration, the information of one rotation of the optical disk can be obtained accurately, so that the focus jump can be stably performed.

Furthermore, since a predetermined driving force for performing a focus jump is simply added to the driving signal of the optical disk before one rotation, a simple calculation procedure can be performed without using a model of the focus actuator. Can focus jump.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, referring to FIGS.
A focus jump control method and an optical disc device according to the present invention will be described.

Embodiment 1 FIG. 1 is a block diagram showing a configuration of an optical disk apparatus according to Embodiment 1 employing a focus jump control method according to the present invention. First, the optical head 2
The internal structure will be described. The laser light source 3 includes a laser diode, a driving circuit that drives the laser diode to emit light, a collimating lens that converts divergent laser light emitted from the laser diode into parallel light, and the like, and emits parallel laser light. The emitted laser light has its optical path bent by the beam splitter 4 and enters the objective lens 5. The objective lens 5 focuses the light beam to form a minute light spot on the recording surface a of the optical disc 1. Optical head 2
Inside, a focus actuator 7 is provided. The focus actuator 7 can move the objective lens 5 in a direction perpendicular to the optical disc 1 and move the focused light spot in a focus direction perpendicular to the optical disc 1.

A tracking actuator for moving the objective lens 5 in the radial direction of the optical disk 1, that is, in the tracking direction is also incorporated therein, although not shown here, since it does not directly relate to the understanding of the present invention. 1 is also moved in the radial direction.

The light reflected on the surface of the recording surface a of the optical disk 1 passes through an objective lens 5 and a beam splitter 4 and a photo detector 6 for generating a focus error signal.
Incident on. The photodetector 6 receives the reflected light modulated by the distance to the recording surface a of the optical disc 1.
The focus error detector 8 outputs to the focus jump control circuit 9 a signal corresponding to the displacement of the light spot with respect to the optical disc 1 based on the change in the intensity of the received reflected light.

FIG. 2 is a flowchart showing a control procedure of a focus jump control method in the optical disk device of FIG. Here, the focus jump control circuit 9
The operation of the control circuit 9 for controlling a light spot and reproducing data will be described on the assumption that the control circuit 9 performs digital control at a constant sampling period T.

In a state where data recorded on the recording surface a in FIG. 1 is being reproduced, the switch 10 is connected to the focus error detector 8 side. In this case, the focus actuator 7 is controlled based on the signal from the focus error detector 8 to focus the light spot on the recording surface a. At the same time as this control, although not shown in FIG. 1, as described above, tracking control is performed by the tracking actuator so that the light spot follows the recording track in the radial direction of the optical disk. As a result, data recorded on the recording surface a on the optical disc 1 can be reproduced.

FIG. 3 is a diagram showing an example of the characteristics of the focus error detector 8. The focus error detector 8 has a linear characteristic of -Kfe in the vicinity of each of the recording surfaces a, b,... here,
The sign “−” means that when the focus error becomes positive, the output voltage becomes negative, and feedback control operates to reduce the error. The signal of the focus error detector 8 is input to the compensator 11. Compensator 11
Is a compensator having characteristics designed so that the focus control system is stable, and usually uses a compensation method such as phase lead / lag compensation or PID compensation. Compensator 11
Generally has a second-order filter characteristic, and can also be realized by digital arithmetic processing. The output of the compensator 11, that is, the drive voltage command Vs is amplified by the amplifier 12, and is input to the lens actuator 7 as the drive signal Va to drive the objective lens 5. When the focus error is compensated in this manner, the objective lens 5 can be stably held at a position separated from the recording surface a by the focal length of the lens.

FIG. 4 is a diagram showing an example of the waveform of the drive voltage signal Va applied to the lens actuator 7 during data reproduction. The output of the compensator 11, that is, the drive voltage command Vs is amplified by the amplifier 12, and is input to the lens actuator 7 as the drive signal Va to drive the objective lens 5. The drive voltage waveform Va is a periodic sinusoidal waveform having a DC offset. The DC offset is an offset voltage for generating a force for keeping the objective lens 5 from moving by a constant external force such as gravity. The sinusoidal variation compensates for the positional variation of the recording surface that occurs when the optical disc 1 rotates, that is, the so-called surface deflection of the optical disc 1 due to the warp of the optical disc 1 or the inclination when the optical disc 1 is chucked. When the optical disk 1 rotates, the recording surfaces a, b,... Vibrate in a direction perpendicular to the surface of the optical disk 1 (vertical direction in FIG. 1). In accordance with the vibration, the objective lens 5 is moved in the same manner, and the objective lens 5 and the recording surfaces a, b,... Are controlled so as to keep a constant distance. Therefore, the offset value of the drive waveform changes according to the manner of placing the optical disk device, that is, the direction of gravity, and the amount of change changes according to the amount of surface deflection of the optical disk 1.

FIG. 5 shows an example of the characteristics of the amplifier 12. The amplifier 12 having the amplification factor Ka has the drive command voltage Vs
Is amplified and applied to the lens actuator 7. The amplification factor of the amplifier 12 is Ka, but the output voltage is ± Vama
Saturates at x. The drive voltage signal Va has a waveform that is Ka times the drive command waveform in a range where the amplifier 12 is not saturated. The force F generated by the lens actuator 7 when the driving voltage is Va is represented by R
Assuming that a is a and the force constant is Kt, it is expressed by Equation 1.

[0031]

(Equation 1)

When the displacement of the objective lens 5 is x, the equation of motion is as follows: the mass of the objective lens 5 is M, and the viscous resistance is D.
, The spring constant is K, and the external force acting on the objective lens 5
When (mainly the focus direction component of gravity) is FL, it is expressed by Expression 2.

[0033]

(Equation 2)

FIG. 6 is a block diagram showing the relationship between the drive voltage of the lens actuator 7 and the relative displacement of the objective lens 5. The difference between the displacement x and the surface deflection xd of the optical disc 1 is the relative distance between the focal point of the light spot and the recording surfaces a, b,... And is detected as a focus error. This is shown by a control block in FIG. The surface deflection of the optical disk 1 is usually caused by the warp of the optical disk 1 itself, the inclination of the optical disk 1 due to chucking, and the like, and appears as a fluctuation synchronized with the rotation of the optical disk 1. Therefore, it can be considered that the surface run-out is hardly changed between the recording surface a and the recording surface b. Further, in a state where the rotation of the optical disk 1 is stable, if the drive signal is delayed by one rotation of the optical disk 1, the surface deflection occurring in real time can be accurately described and compensated.

At the time of data reproduction, the servo system controls the focus error, that is, the relative displacement xm to be substantially zero. FIG. 6 is a block diagram obtained by equivalently converting FIG.
6 (b) and FIG. 6 (c), a driving force for compensating for external force and surface deflection is applied to the objective lens 5, and
Are displaced following the surface deflection of the optical disk 1, and the error between the focal point of the light spot and the recording surfaces a, b,. That is, at the time of data reproduction, control is performed so that the drive signal Va becomes equal to Vac and the relative displacement becomes 0, as shown in Expression 3.

[0036]

(Equation 3)

FIG. 7 is a flowchart showing an example of a processing procedure for realizing the delay means 13 for delaying the drive signal by one rotation of the optical disk 1 by software. In the first embodiment, during the data reproduction, a drive signal necessary for a focus jump is written in the memory. That is, the drive signal command value is stored in the memory in order to realize the delay means 13 for delaying the drive signal by one rotation of the optical disk 1 by software.

The drive command value is sequentially written into the memory for each sample on the basis of the point at which the drive command value crosses zero from negative to positive. First, a pointer that specifies a memory address is incremented. The drive command value Vs is input, and by checking the change in the sign of the command value MVs (AP) one sample before, it is checked whether the signal crosses from negative to positive. When zero crosses from negative to positive, the memory MVs (A
Write data “END” to P). The pointer is cleared (AP = 0) and the drive command value is set to the address MV
Write to s (AP) (= MVs (0)). If the value does not cross zero, the drive command value is written to the address MVs (AP) indicated by the pointer. In the next sampling, the address is incremented, the pointer is moved to the next address, and the current driving force is written. According to this procedure, the drive command value of the drive signal during one rotation of the optical disc 1 is continuously stored in the memory.

In this method, since the command value is stored for each sample, the recording amount differs depending on the change in the rotation cycle of the optical disk 1. However, since the reference is obtained from the drive signal, information on the rotational position of the optical disc 1 is not required.

Next, the focus jump operation for moving the light spot to the recording surface b from the state where the data on the recording surface a is being reproduced will be described. When performing a focus jump, the mode discriminator 22 is operated by a focus jump command from a system controller (not shown).
The switch 10 is connected to the detection gain amplifier 16. When the focus jump operation starts, the target value generator 17 generates and outputs a target value of a position to be moved. Adder 19
Is the target value and the focus actuator model 15
And outputs an error from the target value. The detection gain amplifier 16 amplifies the error from the target value and outputs the result to the compensator 11 via the switch 10.
The compensator 11 outputs a drive command Vs. Amplifier 12
Amplifies the drive command Vs of the compensator 11 and applies it to the focus actuator 7 so that the focus position of the light spot follows the target value of the target generator 17.
Drive. Thereafter, when approaching the recording surface b, the mode discriminator 22 switches the switch 10 to the focus error detector 8 side, and shifts to the data reproduction state described above.

In the first embodiment, the relative distance is detected using the focus actuator model 15.
The characteristic of the focus error detector 8 is as shown in FIG.
Since the recording surfaces a, b,... Include a discontinuous signal in which the error signal becomes 0 and there are many positions (focus errors) for the same voltage value, the recording surfaces a, b,. This is because the relative distance between the light spot and the focal position of the light spot cannot be detected. The focus actuator model 15 has as a characteristic the relationship between the drive voltage input to the focus actuator 7 and the displacement of the objective lens 5.

Returning to the flowchart of FIG. 2, the focus jump control method for moving the focal position of the light spot from the recording surface a to the recording surface b will be described in detail. When a focus jump command comes from the system controller,
The focus jump operation flag is set, and the focus jump process is started. The target value generator 17 generates a target value that gradually changes to a distance (DL) to be moved. The target value generator 17 is, specifically, a digital filter having the characteristics of a low-pass filter having a time constant of about 1 ms. And gradually change to the final movement amount DL. The reason why the target value of the movement amount is gradually changed is to prevent an overshoot due to an excessive jump.

Next, a method for estimating the relative distance between the recording surface a and the focal position of the light spot will be described. As shown in FIG. 4, the objective lens 5 moves relative to the optical disc 1 by an amount obtained by subtracting a signal for compensating external force and surface deflection from the drive signal. As a result, the focal position of the light spot moves relative to the recording surface a. The relative distance from the recording surface a is obtained by subtracting the drive command value Vsc one cycle before the rotation of the optical disk from the drive command Vs output from the compensator 11, and obtaining the difference signal Vsm from the gain amplifier 1.
4 and the actuator drive voltage Vam is input to the focus actuator model 15 for estimation.

FIG. 8 is a flowchart showing a processing procedure for reading the drive command value one rotation before the optical disc 1.
During the focus jump operation, if the data stored in the memory is sequentially read out during the data reproduction, a drive signal at the time of the data reproduction can be obtained within the time when the optical disk 1 makes one rotation.

First, the pointer is incremented, and the drive command value MVs (AP) recorded at that address is read. If the drive command value is “END”, the pointer is cleared (AP = 0) and the drive command value M of the head address is cleared.
Read Vs (AP). According to such a procedure, the drive command value Vsc one rotation before the optical disc 1 can be read.

Thereafter, a difference Vsm between the current drive command value Vs and the drive command value Vsc one rotation before the optical disc 1 is obtained,
The signal is amplified by the gain amplifier 14 having the gain Ka to obtain the actuator drive voltage Vam. At this time, the gain amplifier 14
Has a saturation characteristic shown in FIG. 5, and considering that, when the driving voltage exceeds Vamax, Vam = Vam
ax. Conversely, when the driving voltage is equal to or less than -Vamax,
= -Vamax. The drive voltage Vam is input to the focus actuator model 15 to determine a relative displacement xm. The focus actuator model 15 has a second order characteristic (G (s)) of the denominator shown in Expression 4 and FIG.
Is a model with

[0047]

(Equation 4)

In order to realize this characteristic by a discrete-time digital operation, a calculation formula is derived using a z-transform. Expression (4) is expressed as Expression (5) as a function G (z) of Z using bilinear transformation. Here, T is a sampling period, and each coefficient is expressed by Expression 6.

[0049]

(Equation 5)

[0050]

(Equation 6)

FIG. 9 is a control block showing the operation of the digital filter. In FIG. 9, U is an input, Y is an output, and x ₁ and x ₂ are state quantities. The subscript k represents a value at time t = kT. 1 / z represents a time delay of the sampling period T. That is, when a time-varying input U (k) is given, the output Y of the element having the characteristic of G (s)
(k) is obtained by the operation of Expression 7. Where x ₁ (k)
Is a value obtained from input, output, etc. one sample before. Thereafter, x ₁ (k + 1) and x ₂ (k + 1) used in the next sample are obtained. Thereby, the output Y when the input U is added to the element having the characteristic of G (s) can be calculated.

[0052]

(Equation 7)

[0053]

(Equation 8)

[0054]

(Equation 9)

More specifically, if the input of the focus actuator model 15 is Vam and the output is Pam,
The output Pam can be calculated by Expression 10. Equation 11,
In Expression 12, x ₁ and x ₂ are updated.

[0056]

(Equation 10)

[0057]

[Equation 11]

[0058]

(Equation 12)

By the above calculation procedure, the relative distance Pam between the recording surface a and the focal position of the light spot can be estimated using the model of the focus actuator 15. here,
The relative distance to the recording surface b can be obtained by subtracting the estimated relative distance to the recording surface a from the distance DL to be moved.

In the method of calculating the focus actuator model, although the coefficients are different, the compensator,
It is also used for calculating the target value generator.

The error Eam between the estimated position error Pam and the target value Ram output from the target value generator 17 is amplified by the detection gain amplifier 16 and input to the compensator 11. The detection gain amplifier 16 determines the gain Kfe of the focus error detector 8.
Has the same gain as. When the same gain Kfe is used in this way, the difference when switching to the data reproduction operation can be reduced, and the gain characteristics of the focus control system can be made the same between data reproduction and focus jump.

Thereafter, in the same manner as in data reproduction, the output of the detection gain amplifier 16 is calculated based on the characteristics of the compensator 11, a drive signal command Vs is output, amplified by the amplifier 12, and applied to the lens actuator 7. The objective lens 5 is driven.
The focal position of the light spot approaches the recording surface b, and the estimated relative position Pam approaches the moving distance DL. When the deviation falls below a certain value e, the focus jump flag is reset.

In the optical disc apparatus of FIG. 1, the focus jump operation is completed by the mode discriminator 22, the switch 10 is connected to the focus error detector 8, and thereafter, the control at the time of data reproduction is performed.

According to the first embodiment, the drive signal one rotation before the optical disc 1 is compared with the drive signal at the present time, the position during the focus jump is estimated by using the focus actuator model 15, and the position of the target position is determined. Since the objective lens 5 is controlled based on the error signal, the focus jump can be stably and reliably performed irrespective of external force such as gravity and disturbance such as surface deflection of the optical disc 1.

Embodiment 2 FIG. 10 is a block diagram showing the configuration of an optical disk apparatus according to a second embodiment employing the focus jump control method according to the present invention. The second embodiment differs from the first embodiment in FIG. 1 in that the rotation angle information of the spindle motor 20 is input to the delay unit 13. In the second embodiment, the rotating shaft of the spindle motor 20 includes:
The position detector 21 is attached, and the output is input to the delay means 13.

In the first embodiment, one rotation of the optical disk 1 is determined based on the zero cross signal of the drive signal. In the second embodiment, however, the rotation position of the optical disk 1 is input, so that the drive corresponding to the rotation position of the optical disk is performed. What is necessary is just to store a signal. In this case, a fixed storage area is sufficient regardless of the rotation speed of the optical disc 1. Further, when the surface deflection of the optical disc 1 includes not only the first-order component synchronized with the rotation but also a higher-order component, the zero cross point of the drive signal waveform is not always one point. In the second embodiment, even in such a case, one rotation of the optical disc 1 can be accurately determined.

In the second embodiment, it has been described that the position detector 21 is installed on the rotating shaft of the spindle motor 20 to detect the rotation information. As another method, a method of detecting rotation information of the spindle motor 20 from a drive circuit (not shown) of the spindle motor 20 can be adopted.

According to the second embodiment, an extra storage area for storing drive signals is not required, and only a small storage area is required. Further, even when a high-order vibration component is included, the delay of one rotation of the optical disc 1 is accurate, and the focus jump can be stably performed.

<< Embodiment 3 >> FIG. 11 is a block diagram showing the configuration of an optical disk apparatus according to a third embodiment employing the focus jump control method according to the present invention. In the third embodiment, a predetermined driving force required to move the optical disk 1 is simply determined by a driving signal at the time of data reproduction one rotation before without estimating a relative position between the focal point of the light spot and the recording surface a. This is a method of adding and applying the result to the focus actuator.
The focus jump drive signal generator 23 outputs a drive signal necessary for moving between the recording surfaces a, b,.

The switch 10 includes a compensator 11 and an amplifier 12
The switch 10 is connected to the adder 18 during the focus jump operation. Mode discriminator 22
Switches the switch 10 to the adder 18 when the focus jump command is received, and shifts to the focus jump operation. The focus jump drive signal generator 23 outputs a predetermined drive voltage to the adder 18. Adder 18
Adds the drive voltage from the focus jump drive signal generator 23 to the drive signal from the delay means 13 one rotation before the optical disk 1 to generate a drive command voltage Vs. The amplifier 12 amplifies the drive command voltage Vs of the compensator 11, applies a drive signal Va to the focus actuator 7, and drives the objective lens 5. Thereafter, when it is recognized from the change in the output of the focus error detector 8 that the focal position of the light spot has entered the area of the recording surface b and the focus error shown in FIG. Is
The switch 10 is connected to the compensator 11 to switch to data reproduction.

In the third embodiment, the surface deflection of the optical disk 1 is relatively small, and the drive voltage Va of the focus actuator 7 is small.
If the range is not saturated, a sufficiently stable focus jump can be achieved.

In the third embodiment, it is not necessary to have the focus actuator model 15 as in the first or second embodiment, and the calculation is simplified, so that the circuit configuration is simplified.

The control means used in each of the above embodiments can be realized as digital control in which processing is performed by software using an arithmetic unit such as a microcomputer, and can be realized as an analog circuit such as an operational amplifier. Can also.

Although only the focus error signal is shown in the first embodiment of FIG. 1, the second embodiment of FIG. 10, and the third embodiment of FIG. Control may be performed simultaneously.

Further, it is possible to separate the control means for performing these functions into a plurality of semiconductor elements, or conversely, to form a single semiconductor element together with other semiconductor elements having signal processing functions. is there.

[0076]

In the first embodiment of the present invention, the position during the focus jump is estimated using the focus actuator model based on the drive signal one rotation before the optical disk, and the drive signal at the present time, that is, the target position is estimated. Since the objective lens is controlled based on the error signal from the target position as compared with the position, the focus jump can be stably performed irrespective of an external force such as gravity or a disturbance such as surface deflection of the optical disk.

In the second embodiment, since the drive signal before one rotation of the optical disk can be extracted based on the information on the rotational position of the optical disk, the area for storing the drive signal can be small. In addition, even when there is a high-order vibration, information of one rotation of the optical disk can be obtained accurately, so that the focus jump can be stably performed.

In the third embodiment, the predetermined driving force for performing the focus jump is simply added to the driving signal one rotation before the optical disk, so that the driving signal is simply added without using the focus actuator model. Focus jump can be performed by simple calculation procedure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc apparatus employing a focus jump control method according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of a focus jump control method in the optical disc device of FIG.

FIG. 3 is a diagram illustrating an example of characteristics of a focus error detector.

FIG. 4 is a diagram illustrating an example of a waveform of a drive voltage signal Va applied to a lens actuator during data reproduction.

FIG. 5 is a diagram illustrating an example of characteristics of the amplifier 12.

FIG. 6 is a block diagram illustrating a relationship between a driving voltage of a lens actuator and a relative displacement of an objective lens.

FIG. 7 is a flowchart illustrating an example of a processing procedure for realizing, by software, a delay unit that delays a drive signal by one rotation of an optical disk;

FIG. 8 is a flowchart showing a processing procedure for reading a drive command value one rotation before the optical disc.

FIG. 9 is a control block diagram showing a calculation process of a digital filter.

FIG. 10 is a block diagram illustrating a configuration of an optical disc apparatus according to a second embodiment that employs a focus jump control method according to the present invention.

FIG. 11 is a block diagram showing a configuration of a third embodiment of the optical disc apparatus employing the focus jump control method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical head 3 Laser light source 4 Beam splitter 5 Objective lens 6 Photodetector 7 Focus actuator 8 Focus error detector 9 Control circuit 10 Data reproduction / focus jump changeover switch 11 Compensator 12 Drive command amplifier 13 Delay means 14 Gain amplifier 15 Focus Actuator model 16 Detection gain amplifier 17 Target value generator 18 Adder 19 Adder 20 Spindle motor 21 Position detector 22 Mode determiner 23 Focus jump drive signal generator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Manetsu Soma 111 Nishiyokote-cho, Takasaki-shi, Gunma Prefecture Semiconductor Division, Hitachi, Ltd. Hitachi Image Information System Co., Ltd.

Claims (7)

[Claims] An object lens for irradiating a light spot on one of a plurality of recording surfaces of a rotating optical recording medium; and a focus actuator for moving the objective lens in a direction perpendicular to the plurality of recording surfaces. In a focus jump control method for moving a focal position of a light spot between the plurality of recording surfaces of an optical disc apparatus that positions a light spot on any of information tracks on a plurality of recording surfaces and records or reproduces information, the focus actuator Is delayed by one rotation time of the optical disc, and the relative position between the recording surface and the focal position of the light spot is determined based on the delayed drive signal by a focus actuator model having characteristics equivalent to the focus actuator. Estimate the position and target the real-time focus actuator A focus jump control method, comprising: generating a drive signal for jumping a focal position of a light spot to a different recording surface in accordance with an error between a position and the estimated relative position. 2. An optical system comprising: an objective lens for irradiating a light spot on any of a plurality of recording surfaces of a rotating optical recording medium; and a focus actuator for moving the objective lens in a direction perpendicular to the plurality of recording surfaces. In a focus jump control method for moving a focal position of a light spot between the plurality of recording surfaces of an optical disc apparatus that positions a light spot on any of information tracks on a plurality of recording surfaces and records or reproduces information, the focus actuator Delaying the drive signal by one rotation time of the optical disc, and adding a predetermined drive signal to the delayed drive signal to generate a drive signal for jumping the focal position of the light spot to a different recording surface. Characteristic focus jump control method. 3. An object lens for irradiating a light spot on one of a plurality of recording surfaces of a rotating optical recording medium, and a focus actuator for moving the objective lens in a direction perpendicular to the plurality of recording surfaces, In an optical disc apparatus for recording or reproducing information by positioning a light spot on any of information tracks on a plurality of recording surfaces, means for sequentially storing a drive signal of the focus actuator with a time delay of one rotation of the optical disc, A focus actuator model having characteristics equivalent to a focus actuator and estimating a relative position between the recording surface and the focal position of the light spot based on the delayed drive signal; and outputting a target position to the focus actuator in real time. Target value generating means for performing the calculation, and the target position and the estimation in real time. Optical disk apparatus characterized by comprising a means for generating a drive signal to jump the focal position of the light spot on different recording surfaces according to the error between the relative positions. 4. An objective lens for irradiating any one of a plurality of recording surfaces of a rotating optical recording medium with a light spot, and a focus actuator for moving the objective lens in a direction perpendicular to the plurality of recording surfaces, In an optical disc apparatus for recording or reproducing information by positioning a light spot on any of information tracks on a plurality of recording surfaces, a means for detecting a rotation position of the optical disc; Means for sequentially storing the drive signal of the focus actuator with a time delay of one rotation of the optical disk, and having a characteristic equivalent to that of the focus actuator, and determining a relationship between the recording surface and the focal position of the light spot based on the delayed drive signal. A focus actuator model for estimating a relative position, and the focus actuator Target value generating means for outputting a target position in real time, and a drive signal for jumping the focal position of the light spot to a different recording surface according to an error between the target position in real time and the estimated relative position. An optical disk device comprising: 5. A semiconductor device having a storage unit for storing a delayed drive signal according to claim 3 or 4, a focus actuator model, a target value generation unit, and a jump drive signal generation unit. 6. An object lens for irradiating any one of a plurality of recording surfaces of a rotating optical recording medium with a light spot, and a focus actuator for moving the objective lens in a direction perpendicular to the plurality of recording surfaces, In an optical disc apparatus for recording or reproducing information by positioning a light spot on any of information tracks on a plurality of recording surfaces, means for sequentially storing a drive signal of the focus actuator with a time delay of one rotation of the optical disc, Means for adding a predetermined drive signal to the delayed drive signal to generate a drive signal for jumping the focal position of the light spot to a different recording surface. 7. A semiconductor device having a storage means for storing a delayed drive signal according to claim 6 and a predetermined jump drive signal generation means.