JP2003123291A - Actuator for optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator that can drive an optical element in two directions being a first direction and a second direction that is perpendicular to the first direction with high sensitivity and also does not generate a cross action. SOLUTION: An objective lens driving device 1 supports a holder 3 of a lens unit 2 in two directions of the focusing direction F and the tracking direction T through a support spring 10, a focusing coil 4 is arranged so that its winding axis is parallel to the tracking direction and that its longer sides 4a extend in the tangential direction D, and a tracking coil 5 is arranged so that its winding axis is parallel to the direction D and that its longer sides 5a extend in the focusing direction F. A magnet 6a for directing a magnetic field to the longer sides 4a of the coil 4 is arranged so that poles facing each other are of different polarity, and a magnet 6b for driving a magnetic field to the longer sides 5a of the coil is arranged so that poles facing each other are of the same polarity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to recording and / or reproducing information on an optical recording medium such as a magneto-optical disk drive, a write-once disk drive, a phase change disk drive, a CD-ROM, a DVD and an optical card. The present invention relates to an actuator that drivably supports an optical element such as an objective lens used in an information recording / reproducing apparatus, a coupling lens for an optical fiber used in optical communication, or an objective lens of a scanning microscope.

[0002]

2. Description of the Related Art For example, in an optical pickup actuator used in an optical device such as the above information recording / reproducing device, a focus direction which is a first direction along an axis of an objective lens which is an optical element and a direction orthogonal to the focus direction. It is necessary to support so as to be drivable in two directions, which are the second direction, that is, the tracking direction, and accurately position the light spot of the objective lens on the recording track of the recording medium. Therefore, as an actuator that supports the objective lens so as to be able to be driven in two directions, various actuators having high driving sensitivity have been proposed for the purpose of improving recording density and access speed.

For example, Japanese Utility Model Laid-Open No. 2-30120 (hereinafter referred to as Prior Art 1) proposes an actuator as shown in FIG. This actuator is
The objective lens 40 is held by the holder 41, and two flat mounting surfaces 41f (only one of which is shown in FIG. 10) are arranged to face the holder 41 in the tangential direction D orthogonal to the focusing direction F and the tracking direction T, respectively. The focusing coil 42 and the tracking coil 43 are arranged one by one, and with respect to the focusing coil 42 and the tracking coil 43,
An effective magnetic field is directed from the magnets 44 arranged to face each other through the yoke 45. In the focusing coil 42, this conventional technique is applied to the working sides 42 a, 42.
Using the two sides of b as effective sides, the tracking coil 4
In No. 3, the two sides of the action sides 43a and 43b are used as effective sides for generating an electromagnetic force to enhance the responsiveness (driving sensitivity) of the actuator.

Further, Japanese Patent No. 2620221 (hereinafter, referred to as
An actuator as shown in FIG. 11 has been proposed in Prior Art 2). Since this actuator efficiently generates a driving force in the tracking direction T,
The focusing coil 52 is wound around the outer periphery of the holder 51 that holds the objective lens 50, and the tracking coil 53 is attached to one side surface of the holder 51. The focusing coil 52 and the tracking coil 53 are arranged from the magnets 54a and 54b that are arranged to face each other. An effective magnetic field is directed through the outer yoke 55a and the inner yoke 55b.

[0005]

However, it has been clarified that the following inconveniences occur in the actuator of the optical element according to such a conventional technique.

First, in the actuator as shown in the prior art 1, since the focusing coil 42 and the tracking coil 43 are integrally mounted on the mounting surface 41f arranged in the tangential direction D, the focusing coil 42 and the tracking coil 43 are tracked. There is a limit to the size of the coil 43, and it is difficult to increase the driving sensitivity.

Further, in the actuator as shown in the prior art 2, since the tracking coil 53 is attached to the holder 51 around which the focusing coil 52 is wound, the focusing coil 52 has two of the three magnets 54a and 54b. Only the magnet 54a acts, and the focusing coil 52 in the portion to which the tracking coil 53 is attached (the portion extending along the tracking direction T) is wasted and it is difficult to increase the driving sensitivity.

In addition, both of the above-mentioned prior arts have the inconvenience that the magnitude of the electromagnetic force generated in the focusing coil or the tracking coil is not taken into consideration, so that movement in an undesired direction, so-called cross action occurs. .

The present invention has been made in order to solve the above-mentioned problems, and has a high sensitivity for an optical element in two directions, a first direction and a second direction orthogonal to the first direction. It is an object of the present invention to provide an actuator of an optical element which can be driven by the above method and which does not cause a cross action during the driving.

[0010]

Therefore, an actuator of an optical element according to the first invention comprises a holder for holding the optical element, and a second direction in which the holder is in a first direction and orthogonal to the first direction. Support means for movably supporting in two directions, a first flat coil respectively arranged on two first mounting surfaces of the holder that are separated in the second direction, and first and second holder coils of the holder. A second flat coil disposed on each of two mounting surfaces spaced apart from each other in a third direction orthogonal to the direction, and a second flat coil disposed opposite to each of the first and second flat coils. In an actuator of an optical element having a two-pole magnetized magnet that directs a magnetic field to the first flat coil, a winding axis of the first flat coil is parallel to the second direction, and a long side of the first flat coil is the first flat coil. Is of being disposed on the first mounting surface so as to extend in a direction, also the second flat coil, parallel the winding axes with respect to the third direction,
The long side is arranged on the second mounting surface so as to extend in the first direction, and the magnetic field is inserted to the long side of the first flat coil of the two-pole magnetized magnet. The magnet to be oriented is arranged such that the poles facing each other through the holder are different poles, and the magnetic field is directed to the long side of the second flat coil of the magnet having two poles. The magnet is characterized in that it is arranged such that the poles facing each other through the holder have the same pole.

An actuator for an optical element according to a second aspect of the invention is capable of moving a holder for holding the optical element and the holder in two directions, a first direction and a second direction orthogonal to the first direction. Supporting means for supporting the first flat coil disposed on each of the two first mounting surfaces of the holder that are spaced apart in the second direction, and the first flat coil for the holder.
And a second flat coil disposed on each of two mounting surfaces that are separated in a third direction orthogonal to the second direction, and a second flat coil disposed to face each of the first and second flat coils. In an actuator of an optical element having a two-pole magnetized magnet for directing a magnetic field to the flat coil, the first flat coil has a winding axis parallel to the second direction and a length thereof. The side is arranged on the first mounting surface so as to extend in the third direction, and the winding axis of the second flat coil is parallel to the third direction, and The long side is arranged on the second mounting surface so as to extend in the first direction, and the magnetic field is directed to the long side of the first flat coil of the two-pole magnetized magnet. The magnets have the same poles facing each other through the holder. Among the two-pole magnetized magnets, the magnet that directs the magnetic field to the long side of the second flat coil has different poles facing each other through the holder. It is characterized in that it is arranged as follows.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing an objective lens driving device according to a first embodiment of the present invention, and FIG. 2 is a partially exploded view of FIG.

The objective lens driving device 1 is for recording and reproducing information by converging and irradiating a disc (not shown) such as a CD with a light beam. ) 2a and an aluminum lens frame 2b
A movable holder 3 in which the objective lens unit 2 having a NA of 0.85 is adhesively fixed in the center, supporting means described below for supporting the holder 3 in two directions of the focusing direction F and the tracking direction T, and the holder 3 Two first mounting surfaces 3a separated in the tracking direction T at
Focusing coils 4 which are first flat coils respectively arranged (see FIG. 1) and two second mounting surfaces 3b of the holder 3 which are separated from each other in the tangential direction D.
(See FIG. 1) Tracking coil 5 which is a second flat coil arranged respectively, and focusing coil 4 and tracking coil 5 which are arranged so as to oppose focusing coil 4 and tracking coil 5 respectively. A two-pole magnetized magnet 6a or magnet 6b for directing a magnetic field, and a base 7 adhered and fixed to inner surfaces of the magnets 6a and 6b which are spaced apart in parallel to the tracking direction T and the tangential direction D, respectively.
And an LED (laser diode) 8a that is adhesively fixed to the lower surface of the base 7 and a tracking direction T indicated by a broken line.
And a position sensor unit 9 holding a PD (light emitting diode) 8b divided into two.

The arrows F, T, and D shown in FIGS. 1 and 2 are the focusing direction, which is the first direction parallel to the optical axis O ₁ of the objective lens 2a.
A second direction orthogonal to the tracking direction, and
These focusing direction F and tracking direction T
The tangential direction which is the third direction orthogonal to is shown. Further, in the present embodiment, the central axis of the holder 3 is assumed to coincide with the optical axis O ₁ of the objective lens 2a.

Here, each part of the objective lens driving device 1 will be described in detail.

Since the objective lens unit 2 has the lens frame 2b made of aluminum, the mass of the entire movable portion including the holder 3 supported in two directions of the focusing direction F and the tracking direction T by the supporting means described later can be reduced. The driving sensitivity of the objective lens driving device 1 can be increased to increase the driving sensitivity. In addition, since the frequency of high-order resonance can be increased by changing the type of aluminum, it is possible to support a high disk rotation speed.

As shown in FIGS. 1 and 2, the support means includes two support springs 10 (see FIG. 3), one end of which is adhered and fixed to the upper and lower surfaces of the holder 3 in the focusing direction F, respectively. It is held via a fixing member 11 having the other ends bonded and fixed, and a damping material such as a silicone gel (not shown) filled around the supporting spring 10 and having a box shape covering the periphery of the fixing member 11. And a holding member 12.

FIG. 3 is a perspective view showing the support spring 10. The support spring 10 has two metal leaf springs 10a and 10b extending substantially along the tangential direction T,
These two metal leaf springs 10a and 10b are adhesively fixed to the fixing member 11 so that the distance on the movable side that is adhesively fixed to the holder 3 is smaller than the distance on the fixed side that is adhesively fixed to the fixing member 11. The fixed side is outsert-molded with the resin 10c, while the movable side that is adhesively fixed to the holder 3 is outsert-molded with the resin 10d. As the spring material, a solderable spring material such as phosphor bronze or beryllium copper is used, and its shape is formed by etching or press forming. Further, as the resins 10c and 10d, those having high heat resistance such as liquid crystal polymer and polyetherimide are used to prevent the resin 10c and 10d from being damaged by heat during soldering.

Further, in the vicinity of the fixed side of the metal leaf springs 10a and 10b, as shown in FIG. 3, a bent portion 10e and an L-shaped portion 10f and arm portions 10g, 10h and 10 surrounding them.
have i. The bent portion 10e includes the metal leaf springs 10a, 10
By lowering the spring rigidity in the longitudinal direction of b, the resonant frequency of the tangential direction of the entire movable part including the holder 3 and the rotational resonant frequency around the focusing axis Of (optical axis O ₁ ) are set to frequencies that are easier to control. is doing. When the support spring 10a is bent and twisted, the L-shaped portion 10f has a large displacement at the tip thereof, and has a large deformation effect on the damping material to increase vibration damping. Further, the arm portions 10g, 10h, and 10i prevent the damping material from moving, thereby further increasing the vibration damping effect.

As shown in FIG. 2, the focusing coil 4 has a first mounting surface 3a (so that its winding axis is parallel to the tracking direction T and its long side 4a extends in the tangential direction D. 1), the tracking coil 5 has its winding axis parallel to the tangential direction D and its long side 5a extending in the focusing direction F as shown in FIG. It is adhesively fixed to the second mounting surface 3b (see FIG. 1) so that it exists. As shown in FIG. 2, the focusing coil 4 and the tracking coil 5 are respectively positioned with respect to the first or second mounting surface 3a, 3b by fitting the inner shape of the coil into the convex portion 3p provided on the holder 3. There is.

As shown in FIG. 2, the focusing magnet 6a and the tracking magnet 6b are magnets having one surface magnetized into two poles. The magnet 6a exerting a magnetic flux on the focusing coil 4 is a magnetic pole dividing line. Is a magnet parallel to the tangential direction D, and the magnet 6b that exerts a magnetic flux on the tracking coil 5 is a magnet whose magnetic pole division line is parallel to the focusing direction F.

FIG. 4 is a plan view showing a state in which the focusing magnet 6a, the tracking magnet 6b, the focusing coil 4 and the tracking coil 5 of the objective lens driving device 1 are arranged on the base 7.

In this embodiment, as shown in FIG. 4, a magnet 6 for directing a magnetic field to the long side 4a of the focusing coil 4 is used.
a is arranged on the inner surface of the base 7 so that the polarities facing each other via the holder 3 are different poles (N pole and S pole or S pole and N pole). The magnet 6b, which directs the magnetic field to 5a, has the same polarity (N) facing the inner surface of the base 7 through the holder 3.
Poles and N poles or S poles and S poles).

As a result, when a control current is passed through the focusing coil 4, the focusing direction F is produced in accordance with Fleming's law in cooperation with the magnetic flux of the focusing magnet 6a.
Since an electromagnetic force is generated in the moving part, the entire movable part moves in the focusing direction F. Similarly, when a tracking coil 5 also supplies a control current, an electromagnetic force is generated in the tracking direction T in accordance with Fleming's law in cooperation with the magnetic flux of the tracking magnet 6b, so that the entire movable portion moves in the tracking direction T.

As shown in FIGS. 1 and 2, the focusing coil 4 and the tracking coil 5 are individually arranged on the first and second mounting surfaces 3a and 3b formed on the side surface of the holder 3, respectively. Therefore, the distance between the focusing coil 4 and the focusing magnet 6a and the distance between the tracking coil 5 and the tracking magnet 6b can be set to the minimum value, and the two long sides 4a of the focusing coil 4 and the tracking coil 5 can be set. A magnetic flux can be applied to the two long sides 5a of. Further, according to such a configuration, the sizes of the magnets 6a and 6b can be set to optimal sizes for the focusing coil 4 and the tracking coil 5, so that the driving sensitivity (driving response) can be significantly increased.

As shown in FIG. 2, the position sensor unit 9 has a cantilevered light-shielding member 1 in which the light emitted from the LED 8a extends from the lower surface of the holder 3 in the focusing direction F.
A shadow is created on the two-divided PD 8b to be blocked by 3. At this time, when the holder 3, that is, the objective lens unit 2 moves in the tracking direction T, the shading member 13 fixed integrally moves by the same amount, so that the shadow on the two-divided PD 8b moves. Therefore, the moving direction and size of the objective lens unit 2 can be detected by calculating the difference in photocurrent between the PDs.

The light-shielding member 13 has an outer diameter of 0.5 (mm).
This is a pipe material made of stainless steel, and the weight of the light shielding member 13 itself is reduced as much as possible, and the wall thickness of the pipe is set so that the center of gravity of the entire movable portion coincides with the center of the tracking coil 5. Therefore, the light blocking member 13 also has a function as a balancer.

The base 7 of the objective lens driving device 1 is shown in FIG.
As shown in FIG. 1, the bottom surface is provided with three columnar projections 7a having hemispherical tips (however, in FIG. 1, one of the three projections 7a is provided).
Only the individual is disclosed).

FIG. 5 is an exploded perspective view showing a part of a movable pickup having the objective lens driving device 1 mounted thereon, and FIG. 6 is a perspective view showing the entire movable pickup having the objective lens driving device 1 mounted thereon. is there.

A carriage 21 constituting the movable optical system 20 shown in FIG. 5 has a mirror 22 fixed at an angle of about 45 degrees near its center, and its upper surface is centered near the nodal point of the objective lens. 3 partial spherical surfaces 21a
Therefore, each of these partial spherical surfaces 21a has a base 7
It is in contact with the protrusion 7a (see FIG. 2). Walls are provided around the three partial spherical surfaces 21a so as to surround the projection 7a, and the adhesive applied to the partial spherical surfaces 21a does not flow out when the tilt of the objective lens driving device 1 is adjusted. Is designed to be.

Further, as shown in FIG. 5, a coarse seek coil 23 is adhered and fixed to both side surfaces of the carriage 21, and an FPC (flexible printed circuit) 24 is adhered to this bottom surface via an adhesive material. ing. The F attached around the base 7 of the objective lens driving device 1
The tip of the PC 14 is on the bottom surface of the carriage 21 and the FPC 24
And is connected by soldering.

Further, as shown in FIGS. 5 and 6, the carriage 21 reduces the impact at the time of collision on the side surface of the spindle motor 31 (see FIG. 6) side and the fixed optical system 32 (see FIG. 6) side which will be described later. A damper 25 made of an elastic material such as butyl rubber or resin is attached. The damper 25 has a conical shape with its tip cut off, and a hole is formed in the central axis portion so that the tip is soft and easily crushed.
The root part is thick and has a shape that does not easily collapse. Damper 2
According to the fifth aspect, even when the movable optical system 20 collides with the side surface of the spindle motor 31 side or the fixed optical system 32 side at a low speed, the shock can be absorbed by the tip of the damper 25 being largely crushed. Further, in the case of a collision at a high speed, the thick root portion of the damper 25 firmly receives it, which has the effect of suppressing the impact peak.

As shown in FIG. 5, a thermistor 26 is attached to the FPC 24, and the thermistor 26 detects the internal temperature of the objective lens driving device 1. A trimmer 27 is provided next to the thermistor 26. By adjusting the resistance value of the trimmer 27, the output sensitivity of the objective lens position sensor unit 9 is adjusted to the target value. The cover 28 is fixed to the carriage 21 so as to completely cover the objective lens driving device 1. The gap created at the mating portion of the carriage 21 and the cover 28 is
It is closed by filling it with a room temperature curing type silicone adhesive.

On the side surface of the cover 28, as shown in FIG.
A filter (not shown) is sandwiched and fixed between the pressing member 29 and the cover 28. The pressing member 29 is the pressing member 29.
It is fixed to the cover 28 by fitting the claw provided on the cover 28 into the recess of the cover 28. When the filter becomes dirty, the pressing member 29 can be removed from the cover 28 to replace the filter. In the objective lens driving device 1, when the disc (not shown) is rotated, the air sucked from the upper hole of the cover 28 is replenished through the filter by the Venturi effect. Is kept clean and free of dust.

As shown in FIG. 6, the movable pickup 30 has a movable optical system 20, a spindle motor 31, and a fixed optical system 32 integrally mounted on a chassis 30a.

Spindle motor 31 and fixed optical system 3
As shown in FIG. 6, 2 is screwed and fixed to the chassis 30a together with two sets of coarse seek magnetic circuits 33 and two guide rails 34. The movable optical system 20 has a slide bearing 21b (see FIG. 5) of the carriage 21 supported by two guide rails 34, and the movable optical system 20 is movable in the tracking direction T. Coarse seek magnetic circuit 3
3 comprises a side yoke 36 to which a magnet 35 is adhesively fixed and a center yoke 37 which passes through the coarse seek coil 23 of the movable optical system 20. A magnetic flux in the focusing direction F is applied to the upper side of the coarse seek coil 23 of the movable optical system 20. Influence
When a current is passed through the coarse seek coil 23, a force is generated in the tracking direction T, and the movable optical system 20 is controlled to move in the tracking direction T.

As shown in FIG. 5, the laser light emitted from the fixed optical system 32 is bent by a mirror 22 arranged in the center of the carriage 21 so that it is converged by the objective lens unit 2 to a disc surface (not shown). Collect light. At this time, the “NA” of the objective lens unit 2 is 0.85.
Since the focused light spot is small, the information can be read and written with higher density.

Here, the specific operation of this embodiment will be described.

In the following description, the focusing coil 4 or the tracking coil 5 has an arrangement in which the focusing magnet 6a or the tracking magnet 6b face each other through the holder 3 and have the same polarity (N).
The pole and the N pole or the S pole and the S pole) are referred to as the same pole and the polarities in which the focusing magnet 6a or the tracking magnet 6b in the focusing coil 4 or the tracking coil 5 face each other via the holder 3 are different polarities. The arrangement (N pole and S pole or S pole and N pole) is called opposite poles.

In the magnetic pole arrangement of the first embodiment, as shown in FIG. 4, the focusing magnet 6a has a magnetic pole arrangement with opposite poles and the tracking magnet 6b has a magnetic pole arrangement with the same pole. Magnet 6
It can be seen that the magnetic lines of force of a and the tracking magnet 6b act as shown by arrows in the figure, and the distribution of the magnetic lines has an axially symmetric relationship around the focusing axis Of passing through the center of the figure. Similarly, in the case of the magnetic pole below the focusing magnet 6a, the distribution of magnetic field lines is axially symmetric.

On the other hand, FIG. 7 is a plan view showing a state in which the focusing magnets 6a and the tracking magnets 6b, the focusing coils 4 and the tracking coils 5 having the same poles facing each other are arranged on the base 7. In comparison with the present embodiment of FIG. 4, in the magnetic pole arrangement in which the focusing magnet 6a and the tracking magnet 6b are opposite to each other in the same pole, as shown in FIG. 7, the magnetic force lines generated from the focusing magnet 6a are the axes around the focusing axis Of. Since the relationship is not symmetric, it becomes unbalanced with respect to the tracking direction T.

FIG. 8 is a plan view showing a state in which the focusing magnet 6a and the tracking magnet 6b and the focusing coil 4 and the tracking coil 5 having different magnetic poles facing each other are arranged on the base 7. As compared with the present embodiment of FIG. 4, in the magnetic pole arrangement in which the focusing magnet 6a and the tracking magnet 6b are opposite to each other in the magnetic pole arrangement, as shown in FIG. Since the relationship is not symmetrical, it becomes unbalanced with respect to the tangential direction D.

Table 1 below shows the focusing coil 4 according to the magnetic pole arrangement of the focusing magnet 6a and the tracking magnet 6b used in the objective lens driving device.
It is data calculated by electromagnetic field analysis simulation of the magnitude of the electromagnetic force generated in (indicated by Tr coil in the table) and tracking coil 5 (indicated by Fo coil in the table).

In Table 1 below, focusing magnet 6 is used.
If only a is facing the same pole or opposite poles,
The same pole or the Fo different pole, and only the tracking magnet 6b facing the same pole or the different pole is indicated by the Tr same pole or the Tr different pole. Regarding the numerical values in the table, those with a minus (-) sign represent a force in the direction opposite to the desired force direction, but it is a negative number for the convenience of calculation and can be ignored.

[0046]

[Table 1]

The applicant of the present application also sees from Table 1 that the force in the desired direction for accurate focusing on the disk surface, that is, the magnitude of the force generated in the focusing direction F in the focusing coil 4 and the tracking coil 5 is large. The magnitude of the force generated in the tracking direction T is almost the same in any polarity arrangement, but it has been found that the magnitude of the force generated in an undesired direction greatly differs depending on the polarity arrangement.

The underlined columns in Table 1 show large forces in undesired directions. When the magnetic poles of the focusing magnet 6a and the tracking magnet 6b are opposite to each other in the same pole, as shown in the underlined column of Table 1, a large undesired force is generated in the focusing coil 4 in the tracking direction T and the tracking coil 5 An undesired large force is generated in the focusing direction F. That is, when the focusing magnet 6a and the tracking magnet 6b are arranged so as to face each other with the same pole, when the objective lens driving device 1 is driven in the focusing direction F, the tracking direction T
When the objective lens driving device 1 is driven in the tracking direction T, it also moves in the focusing direction F, so-called cross-action occurs.

Similarly, when the magnetic poles of the focusing magnet 6a and the tracking magnet 6b are opposite to each other,
As shown in the underlined column of Table 1, a large undesired force in the tangential direction D is generated in the focusing coil 4. In other words, when the focusing magnet 6a and the tracking magnet 6b are arranged so as to face each other with different polarities, when the objective lens driving device 1 is driven in the focusing direction F, a cross action that moves also in the tangential direction D occurs.

Therefore, when all the focusing magnets 6a and the tracking magnets 6b are arranged facing each other with the same pole or different poles, as is clear from Table 1, a cross action occurs, so that the objective lens 2a is positioned. It may happen that control becomes difficult and information cannot be read from or written to the disc.

On the other hand, as shown in FIG. 4, the focusing magnet 6a and the tracking magnet 6b are arranged so that the focusing magnet 6a has opposite poles and the tracking magnet 6b has opposite poles. In the case of the first embodiment, the focusing coil 4 is also shown in Table 1.
Also, since the undesired force generated in the tracking coil 5 is the smallest, it is clear that the cross action affecting the positioning control of the objective lens does not occur.

FIG. 9 shows a second embodiment which is a modification of the first embodiment of the present invention. Focusing magnets 6a having magnetic pole arrangements having the same poles facing each other and tracking magnets 6b having magnetic poles having opposite poles facing each other and the focusing are provided. FIG. 6 is a plan view showing a state in which a coil 4 and a tracking coil 5 are arranged on a base 7. The same parts as in the first embodiment are similar to those in FIG.
5 to 5, the same reference numerals are given and the description thereof is omitted.

Also in the second embodiment, as shown in FIG. 9, the focusing magnets 6a are arranged with the same magnetic poles facing each other and the tracking magnets 6b are arranged with different magnetic poles facing each other. The magnetic force lines of the tracking magnet 6b and the tracking magnet 6b act as shown by arrows in the drawing, and the distribution of the magnetic force lines penetrates the center of the drawing.
It can be seen that there is an axisymmetric relationship around f. Also, from Table 1 above, it can be seen that since the undesired force generated in the focusing coil 4 and the tracking coil 5 is the smallest, no cross action affecting the positioning control of the objective lens 2a occurs.

As is clear from the above description, the focusing coil 4 is provided in the first and second embodiments of the present invention.
Is arranged on the first mounting surface 3a of the holder 3 such that its winding axis is parallel to the tracking direction T and its long side 4a extends in the tangential direction D. The tracking coil 5 is arranged on the second mounting surface 3b of the holder 3 such that its winding axis is parallel to the tangential direction D and its long side 5a extends in the focusing direction F. Therefore, it is possible to maximize the size of the focusing coil 4 and the tracking coil 5 to the extent permitted by the individual mounting surfaces 3a and 3b, and, moreover, to increase the long side (operating side) 4a of the focusing coil 4 and the tracking coil 5a. Since 5a can be utilized to the maximum extent, the driving sensitivity can be easily improved.

Particularly, in the first embodiment of the present invention, the magnet 6a for directing the magnetic field to the long side 4a of the focusing coil 4 is used.
Are arranged so that the poles facing each other via the holder 3 are different poles, and the magnet 6b for directing the magnetic field to the long side 5a of the tracking coil 5 is the holder 3
Since the poles facing each other through the poles are arranged so as to be the same pole, it is possible to prevent a cross action that tends to occur when driving the poles, and therefore it is possible to realize highly accurate positioning control of the objective lens. .

Similarly, in the second embodiment of the present invention, the magnet 6a for directing the magnetic field to the long side 4a of the focusing coil 4 is used.
Are arranged so that the poles facing each other through the holder 3 become the same pole, and the magnet 6b for directing the magnetic field to the long side 5a of the tracking coil 5 is the holder 3
Since the poles facing each other through the poles are arranged so as to be different poles, it is possible to prevent a cross action that is likely to occur during driving thereof, and therefore, as in the first embodiment, positioning of the objective lens with high accuracy is possible. Control can be realized.

Therefore, according to the first and second embodiments,
It is possible to provide an objective lens driving device that can drive the objective lens unit 2 with high sensitivity in two directions, ie, the focusing direction F and the tracking direction T, and that does not cause cross action during the driving.

The above description merely shows the preferred embodiments of the present invention, and those skilled in the art can make various modifications within the scope of the claims. For example, the first
Further, in the second embodiment, the optical axis O ₁ of the objective lens 2a is aligned with the central axis of the holder 3 so that the fine adjustment of the objective lens is facilitated. However, the optical axis O ₁ of the objective lens 2a is not necessarily the same. It is not necessary to match the central axis of the holder 3.

Further, in the present embodiment, the actuator of the objective lens used in the recording / reproducing apparatus for the optical disc is exemplified, but the optical element is not limited to the objective lens, but may be a collimator lens or an LD (laser diode). Of course, the device is also applicable to an actuator of a collimating lens for coupling with a fiber of an optical communication device.

[Brief description of drawings]

FIG. 1 is a perspective view showing an objective lens driving device according to a first embodiment of the present invention.

FIG. 2 is a partially exploded view of FIG.

FIG. 3 is a perspective view showing a support spring.

FIG. 4 is a plan view showing a state in which a focusing magnet, a tracking magnet, a focusing coil and a tracking coil of the objective lens driving device of the same embodiment are arranged on a base.

FIG. 5 is an exploded perspective view showing a movable optical system which is a part of a movable pickup equipped with the objective lens driving device of the same embodiment.

FIG. 6 is a perspective view showing an entire movable pickup equipped with the objective lens driving device of the same embodiment.

FIG. 7 is a plan view showing a state in which a focusing magnet, a tracking magnet, a focusing coil and a tracking coil having magnetic poles arranged so as to face each other with the same pole are arranged on a base.

FIG. 8 is a plan view showing a state in which a focusing magnet, a tracking magnet, a focusing coil, and a tracking coil having magnetic poles facing each other with different poles are arranged on a base.

FIG. 9 is a plan view showing a state in which a focusing magnet, a tracking magnet, a focusing coil and a tracking coil are arranged on a base in an objective lens driving device of a second embodiment which is a modification of the first embodiment.

FIG. 10 is a perspective view showing an actuator of an optical element according to a conventional technique.

FIG. 11 is a perspective view showing an actuator of another optical element according to the related art.

[Explanation of symbols]

1 Objective lens drive 2 Objective lens unit 2a Objective lens 2b lens frame 3 holder 3a First mounting surface 3b Second mounting surface 4 Focusing coil 4a long side 5 Tracking coil 5a long side 6a Focusing magnet 6b Tracking magnet 7 base 7a protrusion 8a LED (laser diode) 8b PD (light emitting diode) 9 Position sensor unit 10 Support spring 10a, 10b Metal leaf spring 10c, 10d resin 10e bent part 10f L-shaped part 10g, 10h, 10i arm 11 Fixed member 12 Holding member 13 Light-shielding member 14 FPC () 20 Movable optical system 21 carriage 21a Partial spherical surface 22 mirror 23 Coarse seek coil 24 FPC (flexible printed circuit) 25 damper 26 Thermistor 27 Trimmer 28 cover 29 Presser member 30 movable pickups 30a chassis 31 Spindle motor 32 Fixed optical system 33 Coarse seek magnetic circuit 34 Guide rail 35 magnet 36 Side yoke

Claims (2)

[Claims] 1. A holder for holding an optical element, a support means for movably supporting the holder in two directions of a first direction and a second direction orthogonal to the first direction, and a holder in the holder. First flat coils respectively arranged on two first mounting surfaces that are separated in two directions, and two mounting surfaces that are separated in a third direction orthogonal to the first and second directions in the holder, respectively. Optical element having second flat coil arranged and two-pole magnetized magnet arranged to face each of the first and second flat coils and to direct magnetic field to the flat coil facing each other In the above actuator, the first flat coil is arranged on the first mounting surface such that its winding axis is parallel to the second direction and its long side extends in the third direction. Things Ri, also,
The second flat coil is arranged on the second mounting surface such that its winding axis is parallel to the third direction and its long side extends in the first direction. Further, among the two-pole magnetized magnets, the magnet for directing a magnetic field to the long side of the first flat coil is arranged such that the poles facing each other through the holder are different poles. Of the two-pole magnetized magnets, the magnet that directs the magnetic field to the long side of the second flat coil is arranged such that the poles facing each other through the holder are the same pole. An actuator of an optical element characterized by being a thing. 2. A holder for holding an optical element, a supporting means for movably supporting the holder in two directions of a first direction and a second direction orthogonal to the first direction, and a holder in the holder. First flat coils respectively arranged on two first mounting surfaces that are separated in two directions, and two mounting surfaces that are separated in a third direction orthogonal to the first and second directions in the holder, respectively. Optical element having second flat coil arranged and two-pole magnetized magnet arranged to face each of the first and second flat coils and to direct magnetic field to the flat coil facing each other In the above actuator, the first flat coil is arranged on the first mounting surface such that its winding axis is parallel to the second direction and its long side extends in the third direction. Things Ri, also,
The second flat coil is arranged on the second mounting surface such that its winding axis is parallel to the third direction and its long side extends in the first direction. Further, among the two-pole magnetized magnets, the magnets that direct the magnetic field to the long side of the first flat coil are arranged such that the poles facing each other through the holder are the same poles. Of the two-pole magnetized magnets, the magnet that directs the magnetic field to the long side of the second flat coil is arranged such that the poles facing each other through the holder are different poles. An actuator of an optical element characterized by being a thing.