JP2003141754A - Disk controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk controller, in which stable control is enabled even under the position deviation or vibration of a disk without adding a new sensor, a circuit or the like. SOLUTION: This device is provided with an optical head for forming a light spot by irradiating the recording plane of an optical disk with light and for detecting the reflected light, light spot moving party for moving the light spot vertically to the recording plane of the optical disk or in the direction of its radius, position error detecting circuit for detecting the quantity of deviation from a proper position on the basis of positional information detected by the optical head, PID control circuit for executing phase compensation or the like on the detected deviation quantity, observer for estimating disturbance or the like by using both the detected deviation quantity inputted to the PID control circuit and output from the PID control circuit, output adder circuit for adding the output from the PID control circuit and output from the observer, and driving circuit for driving the light spot moving part on the basis of output in the output adder circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk controller for controlling an actuator of an optical head for reading a signal from a disk. In particular, the present invention relates to a disk control device that controls an actuator that traces an optical head faithfully to a track on a disk.

[0002]

2. Description of the Related Art As a conventional disk controller, the disk controller disclosed in Japanese Patent Laid-Open No. 1-303631 is well known. FIG. 13 is a block diagram of a conventional disk control device.

In FIG. 13, a position sensor 14 provided on the optical head 16 outputs head position information. Further, the speed estimation observer 20 estimates the speed information based on the current information actually flowing through the actuator coil 4 via the drive circuit 23 and the position information.

Then, the estimated speed information and the tracking control output using the error signal detected by the tracking error signal generating circuit 17 amplified by the amplifier circuit 18 are added to drive the actuator coil 4. By determining the output current of the drive circuit 23 that operates, stable tracking control can be realized without providing a phase compensation circuit.

[0005]

In such a disk control device, in order to obtain position information and current information required by the speed estimation observer 20, a position sensor 14 is provided and a circuit for detecting the amount of current is provided. Need to be provided. Therefore, although the control performance of the disk device itself is improved, the cost is increased due to the increase in the number of parts in exchange for that, and the circuit space is expanded,
Consequently, there is a problem that the power consumption increases due to the increase in the circuit scale.

Further, in the conventional disk control device, since the inputs of the normal filter process and the observer process are separate, two completely independent arithmetic processes are required.

Further, when the position information or the current information greatly changes during a transition after the observer is started, for example, when the control is pulled in, the estimated value of the observer is also greatly changed, so that the time until it converges to a stable state is considerably long. There was also a problem that it would become.

In order to solve the above problems, the present invention provides
An object of the present invention is to provide a disk control device that can perform stable control even when the disk is displaced or vibrates without providing a new control circuit and can quickly converge to a stable state.

[0009]

To achieve the above object, a disk controller according to the present invention comprises an optical head for irradiating a recording surface of an optical disk with light to form a light spot and detecting the reflected light. A light spot moving unit that moves the light spot perpendicularly to the recording surface of the optical disc or in a radial direction thereof, and a position error detection circuit that detects the amount of deviation from the optimum position based on the position information detected by the optical head. And a PID control circuit that performs phase compensation or the like for the deviation amount detected by the position error detection circuit, the deviation amount detected by the position error detection circuit that is an input to the PID control circuit, and the PID control circuit An observer for estimating a disturbance or the like using both the output, an output adder circuit for adding the output from the PID control circuit, and the output from the observer, and the output Based on the output of the calculation circuit, characterized in that it comprises a drive circuit for driving a light spot moving unit.

With this configuration, an observer can be introduced without adding new hardware,
It is possible to significantly improve the control performance without increasing the cost or power consumption. Note that it is possible to perform both the processing in the PID filter and the processing in the observer in a time-sharing manner by using one filter.

Further, the disk control device according to the present invention comprises an optical head for irradiating light onto the recording surface of an optical disk to form a light spot and detecting the reflected light, and a light spot perpendicular to the recording surface of the optical disk. Alternatively, a light spot moving unit that moves in the radial direction, a position error detection circuit that detects a deviation amount from an optimum position based on position information detected by the optical head, and a deviation detected by the position error detection circuit. A state determination circuit that determines the control state based on the amount, a PID control circuit that performs at least phase compensation for the amount of deviation detected by the position error detection circuit, and a position that is an input to the PID control circuit. An observer that estimates disturbances and the like using both the deviation amount detected in the error detection circuit and the output from the PID control circuit, and the PID control circuit Output from the observer, an output adder circuit that adds the output from the observer, an observer control circuit that controls ON / OFF of the observer based on the output of the state determination circuit, and an optical spot based on the output from the output adder circuit. And a drive circuit for driving the moving unit.

With such a configuration, by providing an integral term in the observer, stable convergence can be achieved even when the position information and the current information largely change due to pull-in, etc., and the optimum convergence pattern is obtained. It is also possible to match.

Further, the disk control device according to the present invention includes an optical head for irradiating light onto the recording surface of the optical disk to form a light spot and detecting the reflected light, and a light spot perpendicular to the recording surface of the optical disk. Alternatively, the light spot moving unit that moves in the radial direction, the position error detection circuit that detects the amount of deviation from the optimum position based on the position information detected by the optical head, and the deviation detected by the position error detection circuit. The PID control circuit performs phase compensation at least for the quantity, the state determination circuit that determines the control state based on the operation time of the PID control circuit, and the position error detection circuit that is an input to the PID control circuit. An observer that performs an estimation operation using both the deviation amount and the output from the PID control circuit, the output from the PID control circuit, and the observer. An output adder circuit for adding the output from, based on the output of the state decision circuit, Observer ON
An observer control circuit for controlling ON / OFF and a drive circuit for driving the light spot moving unit based on the output from the output addition circuit are provided.

With such a configuration, even by performing time management based on the system control command, it is possible to stably converge to a large change in the position information and the current information at the time of pulling in, and the optimum convergence pattern is obtained. It is also possible.

Further, the disk control device according to the present invention preferably further comprises an integral term preset circuit for setting the integral term of the observer to a predetermined value at the timing of turning on the observer. This is because it can be converged more effectively.

Further, in the disk controller according to the present invention, it is preferable that the integral term preset circuit updates the integral term of the PID filter at the same time when the observer is turned on. This is because it can be converged more effectively.

Further, the disk control device according to the present invention, when the observer is turned on, PI
It is preferable to further include an integral value calculation circuit that calculates the integral term of the observer based on the integral term of the D filter and sets the calculated integral term of the observer. This is because the convergence condition can be dynamically updated according to the situation, and the convergence can be made more effectively.

Further, in the disk control device according to the present invention, it is preferable that the integral value calculating circuit updates the integral term of the PID filter at the same time when the observer is turned on. This is because it can be converged more effectively.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) A disk controller according to Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a first embodiment of the present invention.
It is a block diagram of a disk control device according to. In FIG. 1, reference numeral 16 is an optical head for detecting the reflected light from the disk 1. Reference numeral 4 denotes an actuator coil that drives the objective lens when a current flows. However, the objective lens itself is not shown in FIG.

Reference numeral 17 is a tracking error signal generating circuit for generating a tracking error signal from the output of the optical head 2. That is, the tracking error signal generation circuit 17 detects the amount of deviation from the position to be originally tracked.

Further, reference numeral 8 is a PID control circuit used for normal actuator control, which is a low frequency compensating circuit 8A.
And a proportional operation circuit 8B and a phase compensation circuit 8C.

Reference numeral 40A is a first disturbance estimation observer for estimating the disturbance applied to the actuator by using the output of the tracking error signal generation circuit 17 and the output of the PID control circuit 8 as inputs. It will be described later with reference to FIG. A drive circuit 23 drives the actuator coil 4 by supplying a current according to the value obtained by adding the output of the PID control circuit 8 and the output of the first disturbance estimation observer 40A.

Next, the first disturbance estimation observer 40A will be described in detail with reference to FIGS. First, FIG.
Is a PI that controls the actuator suspension
It is a block diagram of a prototype model in which a basic third disturbance estimation observer 40C is incorporated in a D control loop.

In FIG. 3, 9 is an actuator suspension that supports the objective lens by four wires. Further, 41 is V → which converts the voltage value (V) output from the PID control circuit 8 into the driving force (F) of the actuator.
Reference numeral 47 is an F conversion circuit, and 47 is an X for converting the displacement amount (X) of the actuator into the input voltage (V) of the PID control circuit.
→ It is a V conversion circuit.

FIG. 4 shows a third disturbance estimation observer 40C.
3 is a detailed block diagram of FIG. In FIG. 4, Mn is the nominal value of the lens mass supported by the actuator, and s is the Laplace operator. g1 and g2 are constants that determine the characteristics of the disturbance estimation observer. Further, (1 / Mn · 1 / s · 1 / s) in FIG. 4 indicates a model of the actuator of the secondary resonance system.

In the prototype model shown in FIG. 3, the input and output of the PID control circuit 8 are the third disturbance estimation observer 40.
Considering that the block diagram is transformed so as to input C, the block diagram shown in FIG. 5 can be easily transformed without modifying the third disturbance estimation observer 40C.

That is, as shown in FIG. 5, 42 is V → F.
It is an inverse conversion of the conversion circuit 41, and is an F → V conversion circuit that converts the driving force (F) of the actuator into a voltage value (V) output by the PID control circuit 8. Similarly, 48 is the inverse conversion of the X → V conversion circuit 47, which converts the input voltage (V) of the PID control circuit into the displacement amount (X) of the actuator V →
It is an X conversion circuit.

Further, if the configuration of the third disturbance estimation observer 40C is changed to the second disturbance estimation observer 40B shown in FIG. 2, the block diagram of FIG. 5 can be transformed into the configuration shown in FIG. It will be possible. Furthermore, when the V → F conversion circuit 41, the F → V conversion circuit 42, and the V → X conversion circuit 48, which are connected to the input / output of the second disturbance estimation observer 40B, are regarded as the first disturbance estimation observer 40A, FIG.
As shown in, the input and output of the PID control circuit 8 can be input to the first disturbance estimation observer 40A.

In the operation of the disk controller configured as described above, both the PID control circuit 8 and the first disturbance estimation observer 40A are operating during tracking control. Then, the first disturbance estimation observer 40A estimates the disturbance applied to the actuator by using the input and output of the PID control circuit 8, so that the drive command from the PID control circuit 8 can be accurately corrected, and the disturbance can be efficiently generated. Can be suppressed.

As described above, according to the first embodiment, the position sensor and the drive current detection circuit are provided by using the input and output of the PID control circuit 8 as the input of the first disturbance estimation observer 40A. It becomes unnecessary. Therefore, the observer can be introduced without adding new hardware or the like, and the control performance can be significantly improved without increasing the cost or the power consumption.

Further, the input and output in the processing in which the PID control circuit 8 and the first disturbance estimation observer 40A are combined are the same as the input and output in the case of the PID control circuit 8 alone, and these processing are performed by the digital filter. In the case of the above configuration, since the time division processing can be performed as a series of filter processing, the circuit configuration itself can be simplified.

Although the observer is used only for disturbance estimation in the first embodiment, the observer is not limited to the first embodiment because it can also perform velocity estimation and the like.

(Second Embodiment) A disk controller according to a second embodiment of the present invention will be described below with reference to the drawings. FIG. 7 is a block diagram of a disk controller according to the second embodiment of the present invention. In FIG. 7, 43
Components other than 44 are the same as those of the first embodiment shown in FIG.

In FIG. 7, reference numeral 43 is a system controller for controlling the entire system. Reference numeral 44 is a state determination circuit that determines the transition time of the tracking pull-in operation based on the operation command output from the system controller 43 and the tracking error signal output from the tracking error signal generation circuit 17.

The operation of the disk controller constructed as above will be described with reference to the timing chart of FIG.

In FIG. 8, when the system controller 43 outputs a tracking ON system control command in the tracking OFF state, the PID control circuit 8 creates a control signal from the tracking error signal input at that time and pulls in the tracking. It controls the operation. As a result, the actuator coil 4 is driven by the drive circuit 23, and the amplitude of the tracking error signal that has been output in a sinusoidal shape is reduced and the pull-in operation is performed. Then, the state determination circuit 44
Determines from the movements of the system control command and the tracking error signal that the pulling operation is in progress.

When the state determination circuit 44 detects that the tracking error signal is stable at the center value and the off-track amount is within the predetermined range and determines that the steady state has been entered, the first disturbance estimation observer 40A is started. The first disturbance estimation observer 40A will perform disturbance estimation using the tracking error signal near the zero-cross point from the start of processing.

The disturbed tracking error signal at the time of tracking pull-in cannot be said to accurately indicate the movement of the actuator 9. Therefore, using the tracking error signal at the time of tracking pull-in deteriorates the accuracy of disturbance estimation. Become. However, the tracking error signal in the vicinity of the zero-cross point faithfully indicates the movement of the actuator 9, and it becomes possible to perform more accurate disturbance estimation processing.

As described above, according to the second embodiment, the state determination circuit 44 determines the control state from the system control command and the tracking error signal, detects the transition from the pull-in operation to the steady state, and estimates the disturbance. By activating the observer A40A, the first disturbance estimation observer A40A can perform the disturbance estimation with accurate information from the time of activation, and prevent the control from becoming unstable due to the disturbance estimation having a large error. It will be possible.

Further, in the second embodiment, the control state is judged from the system control command and the tracking error signal, but a method of realizing by the time management from the system control command is also possible,
It is not particularly limited to the second embodiment.

Further, in the second embodiment, the operation of controlling the activation of the first disturbance estimation observer 40A in the pull-in operation is described, but the tracking control is disturbed by an external impact or the like in a steady state, for example. Similarly in the case of the first disturbance estimation observer 4
0A can be controlled. That is, it is also possible to perform the control of stopping the first disturbance estimation observer 40A again until the pull-in is completed and the steady state is reached.

Further, although the observer is used for disturbance estimation in the second embodiment, the observer can also be used for velocity estimation and the like, and is not particularly limited to the second embodiment.

(Third Embodiment) A disk controller according to a third embodiment of the present invention will be described below with reference to the drawings. FIG. 9 is a block diagram of a disk control device according to the third embodiment of the present invention. In FIG. 9, 45
Components other than the above are the same as those in the first and second embodiments shown in FIGS. 1 and 7, and description thereof will be omitted. Four
Reference numeral 5 denotes an integral value preset circuit that presets the integral term of the first disturbance estimation observer 40A with a predetermined value according to an instruction from the state determination circuit 44.

The operation of the disk controller configured as described above will be described with reference to the timing chart of FIG.

The tracking pull-in operation from the tracking OFF state is the same as that in the second embodiment, and the PID control circuit 8 which has received the system control command output from the system controller 43 outputs the control signal using the tracking error signal. It will be created, the drawing operation will be performed, and the state will shift to the steady state.

Next, when the state determination circuit 44 determines from the tracking error signal that the steady state has been reached, it gives a command to the integral term preset circuit 45 to preset the integral term of the first disturbance estimation observer 40A at a predetermined value. , Activates the first disturbance estimation observer 40A. First
In the disturbance estimation observer 40A, since the integral term is set to a predetermined value from the start of the operation, an accurate disturbance estimation output is secured from the beginning, and the disturbance of control at the time of starting the first disturbance estimation observer 40A is suppressed. It is possible.

As described above, according to the third embodiment, the state determination circuit 44 determines the control state from the system control command and the tracking error signal, and detects the transition from the pull-in operation to the steady state. Of the first disturbance estimation observer 4A by presetting the integral term of the disturbance estimation observer 40A
0A can perform disturbance estimation assuming a predetermined estimated DC disturbance from the time of startup, and can prevent instability of control due to disturbance estimation having a large error.

Further, in the third embodiment, the control state is judged from the system control command and the tracking error signal, but it is also possible to realize the method by the time management from the system control command, and particularly the present embodiment. It is not limited to the third form.

Further, in the third embodiment, the operation of starting the first disturbance estimation observer 40A and controlling the integral term of the first disturbance estimation observer 40A in the pull-in operation has been described. For example, tracking control is performed by a shock from the outside in a steady state. When the disturbance is disturbed, the first disturbance estimation observer 40A is similarly controlled, the first disturbance estimation observer 40A is stopped until the pull-in is completed and the steady state is achieved, and the integration of the disturbance estimation observer A40A is started at the time of starting. It is also possible to preset the term with a predetermined value.

In the third embodiment, only the integral term of the first disturbance estimation observer 40A is preset, but a method of presetting the integral term of the low frequency compensating circuit 8A in the PID control circuit 8 is also effective. And is not particularly limited to the third embodiment.

Furthermore, although the observer is used for disturbance estimation in the third embodiment, the observer is not limited to the third embodiment because it can also perform speed estimation and the like.

(Embodiment 4) Hereinafter, a disk control device according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 11 is a configuration diagram of a disk control device according to the fourth embodiment of the present invention. 11 in FIG.
The components other than 6 are the same as those of the first to third embodiments shown in FIGS. 1, 7, and 9, and the description thereof will be omitted. 46
In order to prevent the output value to the drive circuit 23 from shifting from the integral term of the PID control circuit 8 according to the instruction of the state determination circuit 44,
It is an integrated value calculation circuit for calculating and setting the integral term of the disturbance estimation observer 40A.

The operation of the disk controller configured as described above will be described with reference to the timing chart of FIG.

The tracking pull-in operation from the tracking OFF state is the same as in the second and third embodiments, and the PID control circuit 8 which receives the system control command output from the system controller 43 uses the tracking error signal. To generate a control signal, perform a pull-in operation, and shift to a steady state.

Next, when the state determining circuit 44 determines from the tracking error signal that the steady state has been reached, it gives a command to the integral value calculating circuit 46, and based on the integral value of the low frequency compensating circuit 8A in the PID control circuit 8 at that time. The integrated value of the first disturbance estimation observer 40A is calculated and set so that the output value to the drive circuit 23 does not shift, and the first disturbance estimation observer 40A is set.
Is started, and the integral term of the low frequency compensation circuit 8A is reset. In the first disturbance estimation observer 40A, since the integral term is set to the optimum value from the start of the operation, the optimum disturbance estimation output is secured from the beginning, and the control disturbance when the first disturbance estimation observer 40A is activated. It is possible to suppress.

As described above, according to the fourth embodiment, the state determination circuit 44 determines the control state from the system control command and the tracking error signal, detects the transition from the pull-in operation to the steady state, and detects the PID. From the integral term of the low frequency compensation circuit 8A in the control circuit 8 to the drive circuit 2
By setting and calculating the integral term of the first disturbance estimation observer 40A so that the output value to 3 does not deviate, and activating the first disturbance estimation observer 40A, the first disturbance estimation observer 40A starts By incorporating the estimated DC disturbance according to the operating state of, it is possible to perform accurate disturbance estimation under optimum conditions and prevent the control from becoming unstable due to the disturbance estimation having a large error.

Further, in the fourth embodiment, the control state is judged from the system control command and the tracking error signal, but a method of realizing by the time management from the system control command is also possible, and particularly the fourth embodiment. It is not limited to.

Further, in the fourth embodiment, the operation of starting the first disturbance estimation observer 40A and controlling the integral term thereof in the pull-in operation has been described. For example, tracking control is performed by a shock from the outside in a steady state. In the same manner as above, the first disturbance estimation observer 40A is controlled, the first disturbance estimation observer 40A is stopped until the re-pull-in is completed and the steady state is achieved, and the integration of the low-frequency compensation circuit 8A is started at the time of startup. The integral term of the first disturbance estimation observer 40A can also be calculated and set from the term.

Further, although the observer is used for disturbance estimation in the fourth embodiment, the observer can also perform speed estimation and the like and is not particularly limited to the fourth embodiment.

[0060]

As described above, according to the disk control device of the present invention, new hardware is added by using the input and output of the PID control processing as the input of the observer processing means for estimating the disturbance or the like. It is possible to introduce an observer without doing so, and it is possible to greatly improve the control performance without increasing the cost and power consumption.

Further, when the control state at that time is detected and the observer processing is turned ON / OFF, or the integral term in the observer is preset at the time of ON, the position information and the current information greatly change at the time of pulling in. Even in this case, it becomes possible to prevent the integral term in the observer from becoming abnormally large and to adjust to the optimum convergence pattern.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a disk control device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a disturbance estimation observer in the disk control device according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a prototype model when a disturbance estimation observer is introduced in PID control.

FIG. 4 is a block diagram of the disturbance estimation observer in the prototype model when the disturbance estimation observer is introduced in PID control.

FIG. 5 is a configuration diagram of a deformation model when a disturbance estimation observer is introduced in PID control.

FIG. 6 is a configuration diagram of a deformation model when a disturbance estimation observer is introduced in PID control.

FIG. 7 is a configuration diagram of a disk control device according to a second embodiment of the present invention.

FIG. 8 is a timing chart showing various signals during tracking pull-in in the disk control device according to the second embodiment of the present invention.

FIG. 9 is a configuration diagram of a disk control device according to a third embodiment of the present invention.

FIG. 10 is a timing chart showing various signals at the time of tracking pull-in in the disk control device according to the third embodiment of the present invention.

FIG. 11 is a configuration diagram of a disk control device according to a fourth embodiment of the present invention.

FIG. 12 is a timing chart showing various signals during tracking pull-in in the disk control device according to the fourth embodiment of the present invention.

FIG. 13 is a block diagram of a conventional disk control device

[Explanation of symbols]

1 disc 4 actuator coil 8 PID control circuit 8A low frequency compensation circuit 8B proportional operation circuit 8C phase compensation circuit 9 Actuator suspension 14 Position sensor 16 optical head 17 Tracking error signal generation circuit 18 amplifier circuit 20 Velocity estimation observer 23 Drive circuit 40A First disturbance estimation observer 40B Second disturbance estimation observer 40C Third disturbance estimation observer 41 V → F conversion 42 F → V conversion 43 System controller 44 State judgment circuit 45 Integral term preset circuit 46 Integrated value calculation circuit 47 X → V conversion 48 V → X conversion

Claims (8)

[Claims] 1. An optical head for irradiating light onto a recording surface of an optical disk to form a light spot and detecting reflected light thereof; and moving the light spot perpendicularly to a recording surface of the optical disk or in a radial direction thereof. Based on the position information detected by the optical spot moving unit and the optical head,
A position error detection circuit that detects a deviation amount from an optimum position, a PID control circuit that performs at least phase compensation for the deviation amount detected by the position error detection circuit, and an input to the PID control circuit. An observer performing an estimation operation using both the shift amount detected by the certain position error detection circuit and the output from the PID control circuit, an output from the PID control circuit, and an output from the observer. A disk control device comprising: an output adder circuit for adding; and a drive circuit for driving the light spot moving unit based on an output from the output adder circuit. 2. The disk control device according to claim 1, wherein both the processing in the PID control circuit and the processing in the observer are time-divisionally performed by using one filter. 3. An optical head for irradiating light on a recording surface of an optical disk to form a light spot and detecting reflected light thereof; and moving the light spot in a direction perpendicular to a recording surface of the optical disk or in a radial direction thereof. Based on the position information detected by the optical spot moving unit and the optical head,
A position error detection circuit that detects the amount of deviation from the optimum position, a state determination circuit that determines a control state based on at least the amount of displacement detected by the position error detection circuit, and a position error detection circuit that detects the state. A PID control circuit that performs at least phase compensation for the generated shift amount; the shift amount detected by the position error detection circuit that is an input to the PID control circuit; and an output from the PID control circuit. An observer that performs an estimation operation using both of the above, an output adder circuit that adds an output from the PID control circuit and an output from the observer, and ON / OFF of the observer based on the output of the state determination circuit. An observer control circuit for controlling the optical spot, and a drive for driving the light spot moving unit based on the output of the output adder circuit. Disk controller characterized by comprising a road. 4. An optical head for irradiating light onto a recording surface of an optical disc to form a light spot and detecting reflected light thereof; and moving the light spot in a direction perpendicular to the recording surface of the optical disc or in a radial direction thereof. Based on the position information detected by the optical spot moving unit and the optical head,
A position error detection circuit that detects a shift amount from an optimum position, a PID control circuit that performs at least phase compensation for the shift amount detected by the position error detection circuit, and an operating time of the PID control circuit. Based on both the state determination circuit that determines the control state, the displacement amount detected by the position error detection circuit that is an input to the PID control circuit, and the output from the PID control circuit An observer that performs an operation, an output adder circuit that adds the output from the PID control circuit and an output from the observer, and an observer control circuit that controls ON / OFF of the observer based on the output of the state determination circuit. And a drive circuit that drives the light spot moving unit based on the output of the output adder circuit. Disk controller. 5. The integration term preset circuit for setting the integration term of the observer to a predetermined value at the timing of turning on the observer.
The described disk control device. 6. The integral term preset circuit is configured such that the P terminator at the same time when the observer is turned on.
The disk control device according to claim 5, wherein the integral term of the ID control circuit is also updated. 7. An integral value calculation circuit for calculating the integral term of the observer based on the integral term of the PID control circuit at the timing when the observer is turned on, and setting the calculated integral term of the observer. The disk control device according to claim 3 or 4, further comprising: 8. The disk control device according to claim 7, wherein the integral value calculation circuit updates the integral term of the PID control circuit at the same time when the observer is turned on.