JP2001067680A - Actuator control device and optical disk device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively perform stable pull-in operation even when an external vibration occurs by directly detecting a speed of an objective lens in the focus direction caused with the external vibration and the speed in the tracking direction and operating an actuator controller so as to reduce respective speeds. SOLUTION: A focusing back electromotive voltage detection means 12 detects a back electromotive voltage generated on a focus actuator 3, and a focusing speed control means 13 generates a focus speed control signal so as to reduce the speed of the objective lens 2 in the direction vertical to a disk surface 1 based on the detection result to send it to a second focusing switching means 14. Further, a tracking back electromotive voltage detection means 22 detects the back electromotive voltage generated on a tracking actuator 4, and generates a tracking speed control signal so as to reduce the speed of the objective lens in the disk radial direction based on the detection result to output it to a first tracking switching means 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator control device and an optical disk device using the same, and more particularly, to a function for detecting and reducing the speed of an objective lens caused by external vibration in the focus and tracking directions. TECHNICAL FIELD The present invention relates to an actuator control device which is provided with a focus pull-in operation and a tracking pull-in operation which are excellent in stability even when external vibrations occur, and an optical disk device using the same.

[0002]

2. Description of the Related Art In an optical disk drive, an actuator (movable part of an actuator) having an objective lens attached thereto.
Is driven in a direction perpendicular to the surface of the optical disk and in a radial direction of the optical disk, thereby controlling focus and tracking. The actuator is composed of a moving coil, a permanent magnet, and the like, like the speaker, and the objective lens moves integrally with the moving coil.

The objective lens and the moving coil are supported by a mechanical spring or a magnetic spring. When an external vibration is applied to the optical disk device, the objective lens vibrates, which is important for focusing and tracking pull-in operations. Failure may occur.

As a method for suppressing the movement of the objective lens due to external vibration and improving the seismic performance, there are a method using an acceleration sensor, a method using a state observer, and the like. And Japanese Patent Application Laid-Open No. 10-134365.

[0005] In the method using the acceleration sensor, the vibration of the objective lens due to vibration can be reduced by directly detecting the oscillating acceleration of the device and adding the detected signal to the drive signal of the actuator. . Also,
The method using a state observer is to have an equivalent model of the actuator in the observer, indirectly detect the swing of the objective lens, and add the detected signal to the drive signal of the actuator, so that the objective The swing of the lens can be reduced. In any method, a control system having high seismic performance can be obtained, and the reliability of the device can be improved.

[0006]

However, the method using the above-mentioned acceleration sensor involves adding new parts, which increases the cost. In addition, it is often impossible to attach an acceleration sensor to the objective lens body due to problems such as space and weight. Therefore, an error occurs between the vibration detected by the acceleration sensor attached to the apparatus and the vibration that actually shakes the objective lens.

On the other hand, in the method using the state observer, since an error occurs due to modeling, individual adjustment is required at the time of mass production.

An object of the present invention is to detect the speed of the objective lens in the focus direction and the speed of the tracking direction caused by external vibration directly, and to control so as to reduce the speed in each direction. An actuator control device that performs inexpensive retracting operation with excellent performance,
And an optical disk device using the same.

[0009]

In order to achieve the above-mentioned object, the actuator control apparatus of the present invention directly controls the speed of the objective lens caused by external vibration in the focus direction and the tracking direction, as described above. Detect and operate to reduce each speed. For this reason, the actuator control device of the present invention includes a focus actuator that drives the objective lens, a sweep control signal generation unit that controls the operation of the focus actuator so that the objective lens moves at a predetermined speed, Focus control signal generating means for controlling the operation of the focus actuator so as to focus on the top, switching means for focus for switching and outputting the output of the sweep signal generating means and the output of the focus control signal generating means, and the focus actuator. Back electromotive voltage detection means for detecting the generated back electromotive voltage, speed control means for controlling the focus actuator so as to reduce the speed in the focusing direction, and the output of the speed control means and the output of the focus switching means are calculated. Means and focus Focus actuator driving means for driving the actuator, a band limiting filter for focusing, a tracking actuator for driving the objective lens, a tracking control signal generating means for controlling the tracking actuator so that the focal point of the objective lens is positioned on a predetermined track, A feed mechanism that moves the objective lens over a wide range,
A feed motor for driving the feed mechanism, a feed motor control signal generating means for controlling the feed motor, a back electromotive voltage detecting means for detecting a back electromotive voltage generated in the tracking actuator, and reducing the moving speed of the objective lens in the tracking direction. Speed control means for controlling the output of the tracking control signal generating means and the output of the speed control means to output the tracking control signal, a tracking actuator driving means for driving the tracking actuator, and a feed motor for driving the feed motor. And a tracking band limiting filter. Also, the switching unit is operated so that the speed control of the objective lens can be performed only during the focus sweep operation or the tracking seek operation in which the feedback control of the actuator is not performed. In addition, during the sweep operation,
If the objective lens may hit the end of the movable range due to vibration or the like, the switching means is operated so as not to perform the speed control. Equipped with the above means, the speed in the focus direction and the speed in the tracking direction of the objective lens caused by external vibrations are directly detected, the speed in each direction is reduced, and the seismic performance at the time of pulling in the focus control and tracking control is improved. can do. Therefore,
The reliability of the device can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of an actuator control device of an optical disc device according to an embodiment of the present invention.

In FIG. 1, 1 is a disk, 2 is an objective lens, 3 is a focus actuator, 4 is a tracking actuator, 5 is a feed mechanism, 6 is a detector, 7
Is a focus error signal detecting means, 8 is a focus control signal generating means, 9 is a focus jump signal generating means,
10 is a focus sweep signal generating means, 11 is a first focus switching means, 12 is a focus back electromotive voltage detecting means, 13 is a focus speed control means, 1
4 is a second focus switching means, 15 is an adder, 16 is a focus actuator driving means, 17 is a tracking error signal detecting means, 18 is a tracking control signal generating means, 19 is a feed control signal generating means, 20
Is the first tracking switching means, and 21 is the second switching means.
A tracking switching means 22; a tracking back electromotive voltage detecting means 22; a tracking speed control means 23; a tracking actuator driving means 24;
5 is a feed motor driving means, 26 is a feed motor, 29 is a spindle motor, 30 is a disk rotation speed detector, 31
Denotes disk rotation control means.

Here, the focusing speed control means 13 and the tracking speed control means 23 have a focusing band limiting filter and a tracking band limiting filter therein, respectively.

Next, the operation of each block of the focus system shown in FIG. 1 and the relationship between the blocks will be described.

The focus actuator 3 moves the objective lens 2 in a direction perpendicular to the surface of the disk 1 so that the light beam emitted from the objective lens 2 is focused on the recording surface of the disk 1. The light reflected from the disk 1 is detected by the detector 6, and the detected signal is sent to the focus error signal detecting means 7 and the tracking error detecting means 17.

The focus error detecting means 7 detects an error in the focal length based on the signal sent from the detector 6, and sends the detected error to the focus control signal generating means 8 as a focus error signal. The focus control signal generating means 8 generates a focus control signal based on the focus error signal so as to reduce the focus error, and outputs the generated control signal to the first focus switching means 1.
Send to 1.

The focus jump signal generating means 9
Generates a focus jump signal for moving the focus from one layer to another layer when the disk 1 has a plurality of layers as a recording / reproducing surface. The generated jump signal is sent to the first focus switching means 11.

The focus sweep signal generating means 10
In addition to the case where the focus control is pulled in, the setting and adjustment of various parameters are performed when the objective lens 2 is mounted on the disk 1.
A focus sweep signal for moving in a predetermined range in a direction perpendicular to the plane of the image is generated. The generated sweep signal is sent to the first focus switching means 11.

First focus switching means 11
Selects one of the focus control signal, the focus jump signal, and the focus sweep signal sent based on the external input signal a, and sends the selected signal to the adder 15.

The focusing back electromotive voltage detecting means 12 is constituted by the circuit shown in FIG. 4, detects the back electromotive voltage generated in the focus actuator 3, and sends the detected back electromotive voltage to the focusing speed control means 13. send. The focus speed control means 13 generates a focus speed control signal for reducing the speed of the objective lens 2 in the direction perpendicular to the surface of the disk 1 based on the sent back electromotive voltage, and generates the generated speed control signal. The signal is sent to the second switching means 14 for focusing.

Second focus switching means 14
Outputs a speed control signal for a predetermined period during the sweep operation based on the external input signal b, and sends the output speed control signal to the adder 15.

The adder 15 adds the output of the first focus switching means 11 and the output of the second focus switching means 14 and sends an addition signal to the focus actuator driving means 16. The focus actuator driving means 16 drives the focus actuator 3 based on the addition signal.

Next, the operation of each block of the focus system will be described in detail. The above-described external input signal a is used to switch between a focus control operation for positioning the focus on the disk surface, a focus jump operation for positioning the focus on another layer, and a sweep operation for focus pull-in, constant setting, and adjustment. Is an external signal. Therefore, the first focus switching means 11 switches the focus control signal, the focus jump signal, and the focus sweep signal in accordance with each operation, and outputs the signal to the adder 15. FIG. 2 shows an external input signal (switching signal) a
Control operation (feedback (FB)
Control operation) and sweep operation.
This is shown as an example of the switching operation of the first focus switching means 11.

As shown in FIG. 2, the above-mentioned external input signal b is Hi when the sweep operation is performed and the sweep signal level is within a predetermined range, and when the sweep signal level is within an operation other than the sweep operation or the sweep operation. Is Lo when the value is outside the predetermined range. Therefore, the second focus switching means 14 outputs the focus speed control signal to the adder 15 only during the sweep operation in which the sweep signal level is within the predetermined range. The reason why the operation range of the speed control is limited in this way is that a malfunction occurs when the objective lens 2 moves near the end of the movable range and hits the stopper. Therefore, the second focus switching means 14 operates so that the speed control operates when the sweep signal level is within the predetermined range during the sweep operation as described above. However, when the movable range of the objective lens 2 is sufficiently large and there is no possibility that the objective lens 2 will collide even if vibration is applied during the sweep operation, it is not necessary to limit the operation range of the speed control.

The focus back electromotive voltage detecting means 12 is constituted by a bridge circuit as shown in FIG. FIG.
Wherein 3 is the focus actuator, 41 is the first resistor, 42 is the second resistor, 43 is the third resistor,
Reference numeral 4 denotes a differential amplifier (difference voltage detecting means).

The focus actuator 3 and the first resistor 41 are connected in series, the second resistor 42 and the third resistor 43 are connected in series, and the focus actuator 3 and the first resistor 41 are connected in series. For ordering, the second
In the order of the resistor 42 and the third resistor 43, the elements 3, 4
1 and the elements 42 and 43 are connected in parallel. And
A connection point between the focus actuator 3 and the first resistor 41 is connected to one input point of the differential amplifier 44, and a connection point between the second resistor 42 and the third resistor 43 is connected to the differential amplifier 4
4 is connected to the other input terminal.

Here, the resistance value of the focus actuator 3 is Rf, the resistance value of the first resistor 41 is R1, the resistance value of the second resistor 42 is R2, and the resistance value of the third resistor 43 is R3.
Rf / R1 ≒ R2 / R3 (3) By satisfying the relationship of the above expression (3), the back electromotive voltage generated in the focus actuator 3 can be detected.

FIG. 5 shows a model when a back electromotive voltage e is generated.
Shown in Set the output voltage of the actuator driver to Vi
n ₊ , Vin ₋ , and the focus actuator 3 and the first
Let V1 be the voltage between the resistors 41 and V2 and let V2 be the voltage between the second resistor 42 and the third resistor 43.
2, V1 = R1 / (R1 + Rf) · (Vin + -Vin - -e) + Vin - ...... (9) equation V2 = R2 / (R2 + R3 ) · (Vin + -Vin -) + Vin - ...... (10) Equations are represented by the above equations (9) and (10).

From the equations (9) and (10), the differential amplifier 4
The output voltage Vout of No. 4 is expressed as follows: Vout = V2−V1 = R1 / (R1 + Rf) · e (11) Expression (11) The value proportional to the back electromotive voltage e is obtained by detecting Vout. can get.

In order to prevent the maximum current flowing through the focus actuator 3 from decreasing, the embodiment satisfies the following relationship: Rf ≧ 10 · R1 (1) Expression 10 · Rf ≦ R2 (2) , The constant of each element is set.

The band limiting filter included in the focus speed control means 13 is a block diagram shown in FIG.
The loop transfer function of the focus speed control is set so as to have a frequency characteristic as shown in FIG. The gain of the open loop transfer function is set to be 0 dB or more at the main resonance frequency of the actuator and the main resonance frequency of the anti-vibration leg provided for earthquake resistance. This is because the objective lens 2
Is shaken at the highest speed because of the main resonance frequency of the actuator and the anti-vibration leg. This is because the speed control is effectively performed at this main resonance frequency. Further, the cutoff frequency on the low frequency side is set higher than the frequency of the sweep signal. This is to prevent the speed control from responding to the sweep signal. In addition, by cutting the DC component of the control signal, it is not necessary to adjust the offset even when an offset voltage is generated in the back electromotive detection circuit. The cutoff frequency on the high frequency side is set in consideration of the seismic specifications of the equipment.

In this embodiment, the focus band limiting filter included in the focus speed control means 13 has a lower cutoff frequency of ω1, an upper cutoff frequency of ω2, and a sweep control signal generating means. The frequency of the sweep signal output from 10 is ωs,
The main resonance frequency of the focus actuator 3 is ωf
Assuming that c, ωs <ω1 <ωfc <ω2 (4) Expression (4) The limited band is determined so as to satisfy the relationship of Expression (4).

Next, the operation of each block of the tracking system shown in FIG. 1 and the relationship between the blocks will be described.
Here, the description of the blocks having the same operation as that of the focus system will be omitted.

The tracking actuator 4 moves the objective lens 2 in the radial direction of the disk 1 to position the light beam on a track on the disk. The feed mechanism 5 moves the pickup in the radial direction of the disk 1 in a range wider than the movable range of the tracking actuator 4.

The tracking error signal detecting means 17
Based on the signal sent from the detector 6, an error in the disk radial direction between the light beam and the track center is detected, and the detected error is output to the tracking control signal generating means 18 as a tracking error signal. The tracking control signal generating means 18 generates a tracking control signal based on the tracking error signal so as to reduce the tracking error, and transmits the generated control signal to the first tracking switching means 20 and the feed control signal generating means 19. And output to

The feed control signal generating means 19 performs two kinds of operations based on the external input signal c. That is, in the case of a tracking control operation for following a track, the feed control signal generating means 19 generates a tracking control signal based on the tracking control signal, and outputs the generated tracking control signal to the second tracking control signal.
To the tracking switching means 21. The feed mechanism 5 moves the pickup so as to follow the objective lens 2 driven by the tracking actuator 4 according to the tracking control signal. Further, in the case of a seek operation traversing a relatively large number of tracks, the feed control signal generating means 19 generates a seek control signal corresponding to the moving distance and transmits the generated seek control signal to the second tracking switching means. 21.

Second tracking switching means 2
1 selects a follow-up control signal and a seek control signal based on the external input signal c, and outputs the selected signal to the feed motor driving means 25.

The tracking back electromotive voltage detecting means 22 comprises:
It has a configuration similar to that of the back electromotive voltage detecting means 12 for focusing shown in FIG. 4, detects a back electromotive voltage generated in the tracking actuator 4, and outputs the detected back electromotive voltage to the tracking speed control means 23. . The tracking speed control means 23 generates a tracking speed control signal for reducing the speed of the objective lens in the disk radial direction based on the input back electromotive voltage, and converts the generated speed control signal into a first tracking signal. Output to the switching means 20.

First tracking switching means 2
0 outputs a tracking control signal to the tracking actuator driving means 24 based on the external input signal c in the case of the above-described tracking control operation, and outputs the speed control signal to the tracking actuator driving means 24 in the case of the above-described seek operation. Output to

FIG. 3 shows an external input signal (switching signal) c.
Tracking control operation (feedback (F
(B) control operation) and a seek control operation.

Tracking actuator driving means 24
Drives the tracking actuator 4 based on the output signal.

The feed motor driving means 25 drives the feed motor 26 based on the output of the second tracking switching means 21 to operate the feed mechanism 5.

Here, the operation of the tracking system will be described for each of the operation modes of the apparatus. The operation modes can be roughly divided into a tracking control operation for following a track and a seek operation for traversing a relatively large number of tracks.

In the case of the tracking control operation, the objective lens 2 is mainly moved by the tracking actuator 4 using the tracking control signal. On the other hand, in the case of the seek operation, the pickup is moved by the feed mechanism 5 and the objective lens 2 by the tracking actuator 4 is moved.
Is not performed. If the objective lens 2 is shaken by the external vibration during the seek operation, the tracking pull-in operation when the seek operation ends and shifts to the tracking control operation becomes unstable. Therefore, during the seek operation, tracking speed control based on back electromotive detection is performed.

The band limiting filter included in the tracking speed control means 23 is a focusing speed control means 13.
Are set so as to have substantially the same characteristics as the band-limiting filter included in. However, since no sweep operation is performed in tracking, the cutoff frequency on the low frequency side is set so as to cut off the DC component of the control signal. The cutoff frequency on the high frequency side is set near the upper limit of the specification value in consideration of the seismic specification of the equipment.

In this embodiment, the tracking band limiting filter included in the tracking speed control means 23 has a lower cutoff frequency of ω3, an upper cutoff frequency of ω4, and a tracking actuator 4.
When the main resonance frequency of ωtc is ωtc, ω3 <ωtc <ω4 (8) Expression (8) The limited band is determined so as to satisfy the relationship of Expression (8).

The tracking back electromotive voltage detecting means 2
Although not shown, the bridge actuator 2 is formed of a bridge circuit similar to the back electromotive force detecting means 12 for focusing as shown in FIG. 4 has been replaced. Here, although not shown, in the tracking back electromotive voltage detection means 22, the focus actuator 3 of FIG. 4 is set as the tracking actuator 4, the first resistor 41 of FIG.
The second resistor 42 is replaced with a fifth resistor, and the third resistor 43 in FIG. 4 is replaced with a sixth resistor. The resistance value of the tracking actuator 4 is Rt, the fourth resistance value is R4, and the fifth resistor is In this embodiment, assuming that the resistance value of R5 is R5 and the resistance value of the sixth resistance is R6, Rt ≧ 10 · R4 (5) Equation 10 · Rt ≦ R5 (6) Equation Rt / R4 ≒ R5 / R6 Expression (7) The relationship of Expressions (5), (6), and (7) is satisfied.

Finally, control of the rotation of the disk will be described. The spindle motor 29 rotates the disk 1,
The disk rotation speed detector 30 detects the rotation period of the rotating disk. The detected rotation cycle of the disk is sent to the disk rotation control means 31. The disk rotation control means 31 controls the disk to rotate at a predetermined rotation period based on the disk rotation period, and drives the spindle motor 29.

As described above, in the present embodiment, the speed in the focus direction and the tracking direction of the objective lens is detected using the back electromotive force generated by the focus actuator and the tracking actuator, and the detected speed is reduced. By controlling both actuators, it is possible to inexpensively perform a stable operation with respect to the pull-in operation at the start of the focus control and the tracking control even when external vibration occurs. Also, by setting the operation timing and control band of each speed control,
Operation can be stabilized. Therefore, the reliability of the device can be improved at low cost.

In the above-described embodiment, the speed control is performed at the time of the sweep operation for pulling in the focus,
Although the operation is performed without distinction from the sweep operation for setting and adjusting various parameters, the present invention is not limited to this. The same effect can be obtained even if the speed control is not operated in the sweep operation for setting or adjustment, or the output is not output by the switching means 14.

[0050]

As described above, the intended object can be achieved by the present invention. That is, by using the back electromotive voltage generated by the focus actuator and the tracking actuator, the speed in the focus direction and the tracking direction of the objective lens is detected, and the speed is controlled for both actuators so as to reduce the detected speed. Regarding the pull-in operation at the start of the focus control and the tracking control, an operation with excellent stability can be performed at low cost even when external vibration occurs. Further, by setting the operation timing and the control band of each speed control, the operation can be stabilized. Therefore, the reliability of the device can be improved at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an actuator control device of an optical disc device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of switching between a focus control operation (feedback control operation) and a sweep operation in the actuator control device of the optical disc device according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a state of switching between a tracking control operation (feedback control operation) and a seek control operation in the actuator control device of the optical disc device according to one embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration example of a focus back electromotive voltage detecting means in the actuator control device of the optical disc device according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a model when a back electromotive voltage occurs in FIG. 5;

FIG. 6 is an explanatory diagram showing frequency characteristics of a focus band limiting filter included in a focus speed control unit in the actuator control device of the optical disc device according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc 2 Objective lens 3 Focus actuator 4 Tracking actuator 5 Feeding mechanism 7 Focus error signal detecting means 8 Focus control signal generating means 10 Focus sweep signal generating means 11 First focusing switching means 12 Focusing back electromotive voltage detecting means 13 Focus Speed control means 14 second focus switching means 15 adder 16 focus actuator driving means 17 tracking error signal detecting means 18 tracking control signal generating means 19 feed control signal generating means 20 first tracking switching means 21 second Tracking switching means 22 Tracking back electromotive voltage detecting means 23 Tracking speed control means 24 Tracking actuator driving means 25 Ri motor driving means 26 feed motor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroaki Ono 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 5D117 BB06 DD03 EE03 EE20 FF07 FF17 FF19 FX06 FX07 GG02 GG06

Claims (12)

[Claims] 1. An actuator control device for a disk drive using a pickup, comprising: a focus actuator for driving an objective lens; and a sweep control for controlling an operation of the focus actuator so that the objective lens moves at a predetermined speed. Signal generation means, focus control signal generation means for controlling the operation of the focus actuator so that the objective lens is focused on the disk, output of the sweep signal generation means and output of the focus control signal generation means Switching means for switching and outputting; a speed detecting means for detecting a moving speed of the objective lens; and operating the focus actuator so as to reduce the moving speed of the objective lens based on an output of the speed detecting means. Speed control means for controlling the speed; Calculating means for calculating an output of the switching means and the output of the control means, the actuator control device characterized by a focus actuator driving means has to drive the focus actuator based on an output of said arithmetic means. 2. The actuator control device according to claim 1, wherein the speed detecting means includes a back electromotive voltage detecting means for detecting a back electromotive voltage generated in the focus actuator, and a band limiting filter. . 3. The back electromotive voltage detection unit according to claim 2, wherein the back electromotive voltage detection unit has a first resistor, a second resistor, and a third resistor, and the first resistor is connected to the focus actuator. The second resistor and the third resistor are connected in series, the second resistor and the third resistor are connected in series with each other, and the second resistor and the third resistor are connected to the focus actuator and the first resistor.
Are connected in parallel, and the focus actuator and the first resistor are arranged in the order of the second resistor.
A voltage detection circuit comprising a bridge circuit arranged in the order of the first resistor, the third resistor, and the resistance value of the focus actuator, the first resistor, the second resistor, and the third resistor. Rf,
When R1, R2, and R3 are satisfied, Rf ≧ 10 · R1 (1) Expression 10 · Rf ≦ R2 (2) Expression Rf / R1 ≒ R2 / R3 (3) Characteristic actuator control device. 4. The sweeping signal output from the sweep control signal generating means according to claim 2, wherein the band-limiting filter has a lower cutoff frequency of ω1, an upper cutoff frequency of ω2, and a frequency of the sweep signal output from the sweep control signal generating means. Where ωs is the main resonance frequency of the focus actuator and ωfc is the limiting resonance band, so that the limited band is determined so as to satisfy the following relationship: ωs <ω1 <ωfc <ω2 (4) 5. The speed control unit according to claim 1, wherein the speed control unit outputs a speed control signal when the sweep control signal generation unit outputs a signal.
An actuator control device, wherein a speed control signal is not output when a signal from the sweep control signal generating means is not output. 6. The speed control unit according to claim 5, wherein the speed control unit is configured to determine whether the output level of the sweep control signal generation unit is out of a predetermined range based on the output of the signal of the sweep control signal generation unit. And an actuator control device that does not output a speed control signal. 7. An actuator control device for a disk drive using a pickup, comprising: a tracking actuator for driving an objective lens; and a tracking control signal for controlling the tracking actuator so that a focal point of the objective lens is positioned on a predetermined track. Generating means; a feed mechanism for moving the objective lens in a wide range; a feed motor for driving the feed mechanism; and a feed motor control signal for controlling the feed motor so that the focal point of the objective lens is positioned on a predetermined track. Means; speed detecting means for detecting the moving speed of the objective lens; speed controlling means for controlling the moving speed of the objective lens to be reduced based on the output of the speed detecting means; and the tracking control signal generating means. And the output of the speed control means. That a switching means, a tracking actuator driving means for driving the tracking actuator based on an output of said switching means, and a feed motor drive means for driving the feed motor, the actuator control device characterized in that it comprises. 8. The actuator control device according to claim 7, wherein the speed detecting means includes a back electromotive voltage detecting means for detecting a back electromotive voltage generated in the tracking actuator, and a band limiting filter. . 9. The device according to claim 8, wherein the back electromotive voltage detecting means has a fourth resistor, a fifth resistor, and a sixth resistor, and the fourth resistor is connected to the tracking actuator. The fifth resistor and the sixth resistor are connected in series, the fifth resistor and the sixth resistor are connected in series with each other, and the fifth resistor and the sixth resistor are connected to the tracking actuator and the fourth resistor. A voltage detecting circuit configured by a bridge circuit connected in parallel and arranged in the order of the fifth resistor and the sixth resistor with respect to the arrangement in the order of the tracking actuator and the fourth resistor, The resistance values of the tracking actuator, the fourth resistor, the fifth resistor, and the sixth resistor are represented by R, respectively.
When t, R4, R5, and R6, Rt ≧ 10 · R4 (5) Expression 10 · Rt ≦ R5 (6) Expression Rt / R4 ≒ R5 / R6 (7) An actuator control device, characterized in that: 10. The band limiting filter according to claim 8, wherein the lower limit cutoff frequency is ω3,
Actuator control characterized in that when the upper cutoff frequency is ω4 and the main resonance frequency of the tracking actuator is ωtc, the limiting band is determined so as to satisfy the following relationship: ω3 <ωtc <ω4 (8) apparatus. 11. The speed controller according to claim 7, wherein the speed controller outputs a signal from the feed motor control signal generator and outputs a signal from the tracking control signal generator. An actuator control device that outputs a speed control signal when the signal is not output, and does not output the speed control signal when the signal of the tracking control signal generation unit is output. 12. A disk device using the actuator control device according to any one of claims 1 to 11.