JPH01248326A - Access control system for optical disk device - Google Patents

Abstract

PURPOSE:To suppress collision vibration between a shaft and a sleeve at the time of moving a positioner at high speed by pressing the sleeve on the shaft by permitting a current to flow so that forces applied on plural coils with independent driving forces and driving directions can be set oppositely to each other around the shaft, and controlling a pressing force and direction. CONSTITUTION:A driving controller 20 changes the driving forces and the rotating directions of the coils (106a-106d) to drive rotatably an objective lens 8 centering the shaft 103 independently, and performs control to press the sleeve 102 on the shaft 103. Also, a command device 21 indicates the force to press the sleeve 102 on the shaft 103 and the rotating direction according to the change of the driving condition of the positioner 3 to the controller 20. In such a way, it is possible to suppress the collision vibration between the shaft and the sleeve at the time of moving the positioner at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an access control system for an optical disk device, and relates to an access control system for an optical disk device, and an objective lens guide mechanism that is configured of a sleeve and a shaft to drive an objective lens in the direction of disk surface runout and track eccentricity. The present invention is useful when applied to an optical disc device having a lens actuator using a sliding bearing.

<Prior Art> FIG. 5 is a block diagram showing an optical disc device according to the prior art. In the figure, 1 is a disk, 2 is a spindle that rotates the disk 1, 3 is a positive mushroom, and a light source 4
, optical parts 5 such as coupling lenses and information/focus/
1 to a rack signal detector 6 and the like are mounted thereon so as to move in the radial direction of the disk 1.

A lens actuator 7 drives an objective lens 8 for focusing the light beam from the light source 4 onto the medium surface of the disk 1 in the direction of the disk 10 surface deflection and in the radial direction of the disk 1. 10 is a base, and 11 is an external position detector, which detects the position of the positioner 3 with respect to the base 10. 12 is an optical disk control device, 13 is a surface runout follow-up control device, 14 is a track eccentricity follow-up control device, 18 is a track jump control device, 15 is a positioner position control device, 16 is a positioner speed control device, 17° and 19 are switches. It is. In addition, a in the figure indicates information/focus/track signal detection @l! 6 signal, b is the signal of the external position detector 11, C is the drive current in the surface runout direction, d is the drive current in the disk radial direction, e is the positioner drive current, f is the signal that controls the switch 19, gb) - Rack An address signal, h indicates a signal for controlling the switch 17, and l indicates a track address signal, respectively.

Conventionally, access in such an optical disk device is generally performed as follows. First, in the initial state, the positioner 3 is positioned at a predetermined position on the base 10. This is done by inputting the signal from the external position detector 11 to the position controlling device 15, which constitutes a closed loop control system. The light beam is positioned on a predetermined track on the medium surface of the disk 1. In this case, the signal from the information/focus/track signal detector 6 is input to the surface runout tracking control device 13 and the track eccentricity tracking control device 14, and the objective lens 8 is driven in the direction of the surface runout and in the radial direction of the disk 1 by closed loop control. It is done by As a result,
Information can be recorded and reproduced on the positioning track.

In such a state, when a command to move the light beam to another track is issued from the optical disc control device 12, the control for following the predetermined track and the positioner positioning control are first cancelled. Next, the positioner 3 moves to a base position approximately corresponding to the commanded track position under speed control by the positioner speed control device 16. At this time,
The moving speed of the positioner 3 is generated by differentiating the signal from the external position detector 11 or the like. When the position control 3 reaches the base position that roughly corresponds to the commanded track position, the speed control of the positioner 3 is released, and the positioner position II control 1
111 The device 15 positions the base 1 at a predetermined position Z. At this time, the transient vibration settling of the position adjustment 3 and the lens actuator 7 is judged from the signal of the external position detector and the signal of the information/focus/track signal detector 6, and the control to follow the track on the medium surface of the disk 1 is activated. do. This is because if the amplitude of the transient vibration of the positioner 3 and the lens actuator 7 is large, control to follow the track on the medium surface of the disk 1 is likely to fail.

After tracking the track, the track address is read from the signal from the information/focus/track signal detector 6. At this time, if
If the positioning track is different from the command track and the difference is small, only the objective lens 8 is moved in the radial direction of the disk 1 by the track jump control device 18 to position the light beam on the command track and the access operation is completed. On the other hand, if the difference is large, the above series of operations is repeated to position the light beam on the commanded track.

In order to speed up access in such an optical disk device, the characteristics of the position 9 and the lens actuator 7 must be improved, and a high-speed drive control system for the position 3 must be implemented.
It is necessary to consider various types of access control methods to reduce the number of access retries, and studies are underway in various fields.

FIG. 6(a) and FIG. 6Tbl are plan views schematically showing the lens actuator 7 using a sliding bearing composed of a sleeve and a shaft as a guide mechanism for the objective lens 8, and its I
-I is a view taken along the arrow. As shown in both figures, a shaft 103 is inserted into a sleeve 102 fixed to a hole formed in the center of a cylindrical coil bobbin 101, and the coil bobbin 101 is rotatable around the shaft 103.
It is slidable in the vertical direction along 3. Further, an objective lens 8 is disposed on the upper part of the coil bobbin 101, and a focusing coil 1 formed in a cylindrical shape on the outer peripheral surface.
05, and four flat tracking coils 106n, 106b.

106c and 106d are attached. Further, arc-shaped permanent magnets 107a are provided on the outside of each of the tracking coils 106a to 106d.

Yoke l08a with 107b fixed inside.

108b are arranged to face each other, and the coil bobbin 10
Permanent magnets 107 are also placed in the holes 101a and 101b formed in 1.
Yoke 10 facing a, 107 b
8c and 108d are integrally formed with the yokes 108a and 108b. Said carp/L, 105, 106
A drive circuit is constituted by a to 106d, permanent magnets 107a and 107b, and yokes 108a to 108d. The lower part of the shaft 103 includes yokes 108a-108d.
This bottom part 8e is fitted to the bottom part 8e. e is screw 10
9 is fixed to the positioner 3.

110 is an optical path conversion mirror of the optical component 5 (see FIG. 5) placed below the objective lens 8, and the coil bobbin 101 and the bottom portion 10 between the objective lens 8 and the optical path conversion mirror 110 are
8e has a hole 101c.

108f is formed.

Although not shown, the coil bobbin 101 has a bottom portion 8e.
is elastically supported. In addition, A in the figure indicates a light beam from a light source (not shown) to the medium surface of the disk 1 (see FIG. 5), and from the medium surface of the disk 1 to the information/focus/track signal detector 6 (see FIG. 5). shows the optical path of

In such a lens actuator 7, there is a gap of 10 to 20 microns between the shaft 103 and the sleeve 102, and the coil bobbin 101 on which the objective lens 8 is mounted is connected to the current flowing through the coil 105, the yokes 108a to 108d, and the permanent magnets 107a and 107b. It is driven in the vertical direction, that is, in the direction of surface runout, along the axis 103 by interaction with the magnetic field of the magnetic circuit. In addition, current flows through the coils 106a to 106d, the yokes 108a to 108d, and the permanent magnet 1.
07 a.

By interaction with the magnetic field of the magnetic circuit consisting of 107b, the axis 10
3 and is driven in the radial direction of the disk 1. Note that the plurality of coils 106a to 106d are normally wired in advance so that rotational force in the same direction is generated by currents of the same polarity, and a pair of lead wires are drawn out from the lens actuator 7 and connected to the control device. . This type of lens actuator has a simple structure and is inexpensive, so it is widely used in compact disc players and the like.

<Problems to be Solved by the Invention> In an optical disc device capable of recording and reproducing information, it is necessary to access a command track in a short time. However,
When the positioner 3 equipped with the lens actuator 7 is moved at high speed using the conventional access control method, collision vibration occurs between the shaft 103 and the sleeve 102 due to changes in acceleration when the positioner 3 accelerates or decelerates.

As a result, even if the positioner 3 is positioned at the base position that roughly corresponds to the command track position and the transient vibration of the positioner 3 is stabilized, it takes a long time to settle the transient vibration of the lens actuator tough, resulting in a long access time. was there.

The purpose of the present invention is to suppress collision vibration between the shaft and the sleeve during high-speed movement of the positioner caused by the gap between the shaft and the sleeve, and to provide a lens actuator with a simple structure and low cost for recording information that requires high-speed accessibility. - The objective is to provide an access control method for optical disc devices that are capable of playback.

Means for Solving the Problems> The structure of the present invention that achieves the above objects includes a sleeve into which a vertical shaft is inserted, a coil bobbin fixed to the sleeve, and a left and right source on the circumferential surface of the coil bobbin. The objective lens is supported by a plurality of coils fixed to the coil bobbin and magnets facing each other on the circumferential surface of the coil bobbin.The interaction between the current flowing through the coils and the magnetic field of the magnets causes the coil bobbin and the objective lens to be axially moved. In an optical disk device that has a lens actuator that rotates around the axis, the driving force and driving direction of multiple coils can be changed independently, and current is applied to each coil so that the force acting on each coil is in the opposite direction to the axis. The sleeve is pressed against the shaft by the flow, and the pressing force and direction are controlled.In addition, the rotational displacement around the axis of the objective lens is detected, and the driving force and driving direction of multiple coils are independently controlled. By applying current to each coil so that the force acting on each coil is in the opposite direction to the rotation of the axis as the driving conditions change, the rotational displacement of the objective lens and the force that presses the sleeve against the axis can be changed. It is characterized by controlling.

<Function> According to the present invention having the above configuration, by appropriately selecting the direction and magnitude of the current flowing through each coil, the objective lens can be rotated around the axis, or the objective lens can be rotated around the axis without being rotated in this manner. It is also possible to press the sleeve against the shaft with a predetermined pressing force. Further, it is also possible to simultaneously control the rotational displacement of the objective lens and the force that presses the sleeve against the shaft.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that parts that are the same as those in the prior art are given the same numbers and redundant explanations will be omitted.

FIG. 1 is a block diagram showing an optical disk device according to a first embodiment of the present invention, and FIGS. It is a top view showing the same). As shown in these figures, this optical disc device is the same as the optical disc device shown in FIG. 5, with a drive control device 20 and a command device 21 added thereto. Among these, the drive control device 20 includes coils 106a to 106a to rotate the objective lens 8 about the axis 103.
The driving force and rotation direction of the shaft 6d can be changed independently to control the pressing of the sleeve 102 against the shaft 103. Further, the command device 21 instructs the drive ff1J@device 20 about the force and rotation direction for pressing the sleeve 102 against the shaft 103 in accordance with changes in the drive conditions of the positioner 3.

Furthermore, the lens actuator 7 according to this embodiment has a coil 106a, as shown in FIG. 2 (a+, (b)).
106b and coil 106c.

106d are connected in series, and these coils 1
06a, 106b and coil 106c.

The drive control device 20 (see FIG. 1) supplies disk radial drive currents dI and d2 to the disks 106d, respectively. That is, these coils 106 n to 106 d
The coils 106a to 106d can be selected from two states: one in which all the coils 106a to 106d simultaneously generate rotational force in the same direction with respect to the shaft 103, and the other in which they generate clockwise and counterclockwise rotational forces in relation to the shaft 103. is connected to. Here, 1
For example, between coils 106a and 106b, coil 106
A wire is connected between C and 106d to generate rotational force, and two pairs of lead wires are drawn out and connected to the drive control device 20, respectively.

In FIG. 1, J indicates a signal instructing the start/release of the operation when pressing the sleeve 102, k indicates driving information of the positioner 3, and Numa indicates a signal instructing the force and direction when pressing the sleeve 102.

Access in such an optical disc device is performed as follows. First, in the initial state, positioner 3
is positioned at a predetermined position on the base 10. This is done by inputting the signal from the external position detector 11 to the positioner position control device 15 to form a closed loop control system. The light beam is positioned on a predetermined track on the medium surface of the disk 1. This is done by inputting the signal a from the information/focus/track signal detector 6 to the surface runout tracking control device 13 and the track eccentricity tracking control device 14, and controlling the objective lens 8 in the direction of the surface runout and in the radial direction of the disk 1. It is done by driving. As a result, information can be recorded and reproduced on the positioning track. As will be detailed later, in the initial state, the driving force generated by the currents d, d2 flowing through the two pairs of coil lead wires 106a, 106b and 06c, 106d is the driving force generated by the shaft 10.
The objective lens 8 is controlled by a drive control device 20 to rotate in the same direction with respect to the objective lens 3.

In such a state, when a command to move the light beam to another track is issued from the optical disc control device 12, the control for following the predetermined track and the positioner positioning control are first cancelled. Next, the optical disc control device 12
A command to start the operation of pressing the sleeve 102 against the shaft 103 is transmitted to the command device 21. The command device 21 receives positioner drive information such as the drive current value and polarity of the positioner 3 from the positioner speed control device 16,
A pressing force that does not cause vibration between the shaft 103 and the sleeve 102 during access is calculated, and the pressing force and direction are commanded to the drive control device 20. The drive control device 2o controls the coils 106a, 106b and 1.06c according to the command.
, 106d, and start energization by setting the polarity, value, etc. of the current flowing through the terminals. Note that the pressing force and direction may be changed as appropriate based on the positioner drive information being accessed, or the initial command values may be maintained.

Next, the positioner 3 is speed-controlled by the positioner speed control device 16 and moves at high speed to a base position that roughly corresponds to the commanded track position. At this time, the moving speed of the positioner 3 is generated by differentiating the signal from the external position detector 11 or the like. Thereafter, when the positioner 3 reaches a base position that roughly corresponds to the commanded track position, the positioner speed control is canceled and the positioner position control device 15 positions the base 10 at a predetermined position.

In such a state, the signal and information of the external position detector 11
Positioner 3 from signal a of focus/track signal detection N6
Then, the optical disk control device 12 transmits a command to the command device 21 to press the sleeve 102 against the shaft 103 and cancel the operation. The command device 21 issues an instruction to the drive control device 20 to reduce the pushing force to zero and cancel the control operation. In this way, the control for following the tracks on the medium surface of the disc 1 operates.

After track following, information/focus/)/rack signal detection w6
Read the track address from signal a. At this time, if the positioning track is different from the command track and the difference is small, only the objective lens 8 is moved in the radial direction of the disk 1 by the track jump control device 18 to position the light beam on the command track and perform the access operation. end. On the other hand, if the difference is large, the above series of operations is repeated to position the light beam on the commanded track.

In this embodiment, since the sleeve 102 is controlled to be pressed against the shaft 103 based on the single movement information of the position 5 3 during access, the gap between the shaft 103 and the sleeve 102 due to the acceleration change during acceleration/deceleration of the position 5 3 is controlled. The occurrence of collision vibration can be suppressed. Therefore, the transient vibration settling time of the lens actuator 7 can be shortened, and access can be made faster. Note that even if no collision vibration occurs, the shaft will undergo elastic deformation due to changes in acceleration and transient vibration will occur, but the time required to settle the transient vibration is about the same as the time required to settle the transient vibration of the position. No problem 0 The shaft 103 of the sleeve 102 in this embodiment as described above
Figure 2 (al) and Figure 2 (bJ
This will be explained in more detail based on the following.

FIG. 2(a) shows when the sleeve 102 is rotated around the shaft 103;
The cases in which it is pressed are shown respectively.

In the case shown in FIG. 2 ta), the coils 106a, 106b
The coil 10 is connected from the terminal 106f to the coil 106b.
The drive current d passing through 6 a ie and reaching the terminal 106e is
Further, the coils 106c and 106d are connected to the terminal 106 from the terminal 106h to the coil 106d, passing through the coil 106c.
A drive current d2 up to g is respectively supplied by a drive control device N20. As a result of B, the coils 106a to 106d have a vector I in the figure due to interaction with the magnetic field generated by the permanent magnets 107a and 107b.

Forces denoted by II, III, and y act. Although the forces indicated by vectors I, II, II, and IV act on each coil 106a to 106d accurately, they are shown a certain distance away from the actual point of application to avoid confusion in the diagram.
The same applies to FIG. 2(b)).

At this time, since the vectors E to I have the same magnitude and the direction shown in the figure, the sleeve 102 rotates around the shaft 103 in a clockwise direction. That is, at this time, the vertical components of the vectors ■ to ■ in the drawings cancel each other out, so the pressing force of the sleeve 102 against the shaft 103 can be ignored, and the horizontal components in the drawings of the vectors ■ to ■ A rotational moment around 103 is generated.

On the other hand, in the case shown in FIG. 2(b), the direction of the drive current d is the same as in the case shown in FIG.
The direction is reversed. That is, at this time, the coil 106c
, 106d has a drive current d that flows from the terminal 106g to the coil 106C, passes through the coil 106d, and reaches the terminal 106h.
2 is supplied by the drive control device 20. As a result, the coils 106a to 106d have coils I and II shown in FIG.

V, the force shown in ■ is applied. Among these, vector I,
I[ is the same in direction and magnitude as those shown in FIG.
The size is the same as that of I and IV, but the direction is 180° different. Therefore, in this case, each vector I, TI,
The horizontal components in the diagram of V and ■ are canceled out, so axis 1
If the rotational moment around 03 is not generated, only the vertically upward component remains.
is moved vertically upward and pressed against the shaft 103. The pressing force at this time can be appropriately set depending on the magnitude of the drive currents d, d2.

FIG. 3 is a block diagram showing an optical disk device according to a second embodiment of the present invention, FIG. 4 is a plan view showing the lens actuator 7, and FIG. FIG.

As shown in FIG. 3, this optical disk device includes a rotational displacement detecting device 9 and a switch 2 in addition to the optical disk device shown in FIG.
2 has been added. The rotational displacement detection bag M9 is composed of a part that detects rotational displacement about the axis 103 of the objective lens 8 and an amplification part,
A rotational displacement signal m is applied to the track eccentricity follow-up control value M14 via a switch 22 controlled by a signal n sent from
Let's supply le.

Furthermore, the lens actuator 7 according to this embodiment has a detection pin 111 as shown in FIGS.
, light emitting diode 112 and two-part photodiode 1
It has 13.

Among these, the detection pin 111 is fixed to the coil bobbin 101 so as to hang vertically downward, and its lower end is connected to the light emitting diode 112 and the two-part photodiode 113.
It is designed to come in between. At this time, detection pin 11
1 is the central axis 10 of the objective lens 8 with respect to the axis 103.
It is placed in a position that is symmetrical to 3. Thus, when the objective lens 8 rotates around the axis 103 as the coil bobbin 101 rotates, the pin 111 moves and the amount of light reaching the two-split photodiode 113 changes, and this change in light amount is converted into an electrical signal. The rotational displacement is obtained by converting to In addition, the coil 106a
-106d are connected in the same way as shown in FIGS. 2(a) and (bl). In the figure, 114 is a sensor poler.

Access to such an optical disc is performed as follows.

First, in the initial state, the base 3 is the base 10.
is positioned at a predetermined position. This is accomplished by inputting the signal from the external position detector 11 to the positioner position control device 15 to form a closed loop control system. The light beam is positioned on a predetermined track on the medium surface of the disk 1. This is information/focus/track signal detector 6
This is done by inputting the signal a to the surface runout tracking control device 113 and the track eccentricity tracking control device 14, and driving the objective lens 8 in the surface runout direction and in the radial direction of the disk 1 by closed loop control. As a result, information can be recorded and reproduced on the positioning track.

In addition, in the initial state (the coils 106a, 106b
The driving force generated by the current flowing through the two pairs of coil drawers d, d2 of the coils 106c and 106d is controlled by the drive control bag M20 so as to rotate the objective lens 8 in the same direction with respect to the shaft 103. .

In this state, when a command to move the light beam to another track is issued from the optical disc control device 2, the control for following the predetermined 1-rack and the positioner positioning control are first cancelled. Further, the function of the l-rack eccentricity follow-up control device 14 to control the current d2 flowing through the lead wires of the coils 106c and 106d becomes inoperable. At the same time, the drive control device 20 starts operating the function of controlling the current d2 flowing through the lead wires of the coils 106c and 106d.

Thereafter, the switch 22 is closed and the operation of controlling the rotational displacement of the objective lens 8 using the rotational displacement signal m from the rotational displacement detection device 9 is started. Next, the optical disc control device 12 transmits a command to the command device 21 to start the operation. The command device 21 calculates the driving force and direction to be generated by the current d2 of the lead wires of the coils 106c and 106d based on the positioner drive information such as the drive current value and polarity sent from the speed control device 16. Then, it instructs the drive control device 20 about the driving force and direction. Drive control device 20
coil 106c according to the commanded driving force and direction.

The polarity, value, etc. of the current d2 flowing through the current 106d are set, and energization is started. When a rotational force is generated in the drive coil of the drawer 111d2 by this control, the rotational displacement caused by the rotational force of the coils 106c and 106d is suppressed by controlling the rotational displacement of the objective lens 8.
6 c.

A rotational force of substantially the same value in the opposite direction is generated at 106d. As a result, the sleeve 102 is connected to the shaft 103 as in the first embodiment.
be forced to. Note that the pushing force is calculated by the command device 21 so that no collision vibration occurs between the shaft 103 and the sleeve 102 during access. Incidentally, the pressing force and its direction may be changed as appropriate based on the positioner drive information being accessed, or the initial command value may be maintained.

Next, the positioner 3 moves at high speed to a base position roughly corresponding to the commanded track position under speed control by the positioner speed control value [16]. At this time, the moving speed of the positioner 3 is generated by differentiating the signal S of the external position detection N11. When the positioner 3 reaches a base position that roughly corresponds to the commanded track position, the positioner speed control is released and the base 10 is positioned at a predetermined position by positioner position control. Thereafter, the transient vibration settling of the positioner and lens actuator is determined based on the signal of the external position detector 11 and the signal of the information/focus/track signal detector 6, and the optical disk control device 12 issues a command to the command device 21 to cancel the operation. communicated. As a result, the command device 21 issues an instruction to the drive control device 20 to make the current zero and cancel the control operation. Further, the switch 20 is opened to cancel rotational displacement control.

Next, the coil 106c is activated at the drive control value W20.

The function of controlling the current d2 of 106d is canceled, and the function starts operating in the track eccentricity following control device [14]. Thereafter, the control for following the track on the medium surface of the disc 1 is operated.

After tracking the track, the track address is read from the signal a of the information/focus/track signal detector 6. At this time, if the positioning track is different from the command track and the difference is small, only the objective lens 8 is moved in the radial direction of the disk 1 by the track jump control device 18 to position the light beam on the command track and perform the access operation. finish. On the other hand, if the difference is large, the above series of operations is repeated to position the light beam on the commanded track.

As described above, this embodiment controls the rotational displacement of the objective lens 8 during access and also controls the pressing of the sleeve 102 against the shaft 103 based on the drive information of the positioner 3. It is possible to suppress rotational vibration of the objective lens 8 due to changes in acceleration as well as collision vibration between the shaft 103 and the sleeve 102. Therefore, the transient vibration settling time of the lens actuator can be shortened, and access can be made faster. Note that even if the above-mentioned vibration does not occur, the shaft is elastically deformed due to changes in acceleration and transient vibration occurs, but the time required to settle the transient vibration is about the same as the time required to settle the transient vibration of the positioner 3, which is particularly problematic. Not.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, collision vibration occurs between the shaft and the sleeve due to acceleration changes during acceleration and deceleration of the object lens during access, and rotational vibration of the objective lens is generated. Also, the occurrence of collision vibration between the shaft and the sleeve can be suppressed. Therefore, the transient vibration settling time of the lens actuator can be shortened, and access can be made faster.

As a result, it has become possible to apply a lens actuator with a simple structure and low price to an optical disk device that is capable of recording and reproducing information that requires high-speed access, realizing an inexpensive, high-performance, and highly reliable optical disk device. There are advantages that can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention, and FIGS. 2(a) and 2(b) show an extracted lens actuator to explain the operating principle of the lens actuator. 3 is a block diagram showing the second embodiment of the present invention, FIG. 4 (al is a plan view showing the lens actuator thereof, and FIG. 4 (bl is the II-II
Line sectional view, Figure 5 is a block diagram showing the prior art, Figure 6 is a block diagram showing the prior art.
FIG. 6(a) is a plan view showing the lens actuator, and FIG. 6(b) is a sectional view taken along the line I--I. In the drawings, 1 is a disk 1, 3 is a body, 7 is a lens actuator A, 8 is an objective lens, 9 is a rotational displacement detection device, 20 is a drive control device, 21 is a lid manufactured by command, 101 is a coil bobbin, 102 is a shaft, 103 is a sleeve, 105 is a coil, 106a to 106d are coils, and 107a and 107b are permanent magnets.

Claims (2)

[Claims] (1) A sleeve into which a vertical shaft is inserted, a coil bobbin fixed to the sleeve, a plurality of coils fixed symmetrically to the circumferential surface of the coil bobbin, and magnets facing each other to the circumferential surface of the coil bobbin. In an optical disk drive having a lens actuator that supports an objective lens and rotates the coil bobbin and the objective lens around an axis by interaction between a current flowing through the coil and a magnetic field generated by a magnet, the driving force and drive of the plurality of coils are The direction can be changed independently, and the sleeve is pressed against the shaft by passing current through each coil so that the force acting on each coil is in the opposite direction to the rotation around the shaft, and this pressing force and direction are controlled. An access control method for an optical disk device characterized by: (2) A sleeve into which a vertical shaft is inserted, a coil bobbin fixed to the sleeve, a plurality of coils fixed symmetrically to the circumferential surface of the coil bobbin, and magnets facing each other to the circumferential surface of the coil bobbin. In an optical disk drive having a lens actuator that supports an objective lens and rotates the coil bobbin and the objective lens around the axis by the interaction between the current flowing through the coil and the magnetic field from the magnet, In addition to detecting rotational displacement, the driving force and driving direction of multiple coils can be changed independently, and each coil can be adjusted so that the force acting on each coil is in the opposite direction around the axis as the driving conditions change. An access control method for an optical disk device, characterized in that the rotational displacement of an objective lens and the force that presses a sleeve against a shaft are controlled by passing a current through.