JPH06197519A - Electromagnetic driving device - Google Patents

Abstract

PURPOSE:To eliminate the need of a counter balance fitted to the bottom of a driving section so that the driving section can be reduced in size and weight and improved in driving sensitivity by shifting the center of the magnetic surface of a first magnetic member against the center of the magnetic surface of a second magnetic member in the direction perpendicular to the direction of a force generated by a coil. CONSTITUTION:In this driving device in which a disk 3 is held by means of a spindle motor fixed on a base 1 and a mover 4 on the base 1 is moved in the X-direction, the center of a magnet 10 in the Z-direction is made higher by Z2 against the centers of a center yoke 6, side yoke 8, and coil 27 in the Z-direction. As a result, the density center (f) of the magnetic flux crossing the coil 27 in the magnetic gap between the yoke 6 and magnet 10 becomes higher than the center of the yoke 6 in the Z-direction by Z2X1/2. Therefore, the mass of the balancer to be provided below a mobile section 4 to align the centroid of the section 4 with a driving center F can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic drive device, and more particularly to an electromagnetic drive device which can be preferably used as a driving means for an objective lens of an optical disk recording / reproducing device.

[0002]

2. Description of the Related Art An electromagnetic drive device used in an optical disk recording / reproducing device is disclosed in, for example, Japanese Patent Laid-Open No. 2-106155. FIG. 9 is a perspective view showing the overall structure of this electromagnetic drive device, and FIG. 10 is a view of the device II shown in FIG.
It is a sectional view taken along the line II.

9 and 10 show a state in which the electromagnetic driving device is used as a driving means of an optical pickup of an optical disk reproducing device. Reference numeral 101 is a linear motor, and this linear motor 101 is arranged on the back side of an optical disc 102 which is rotatably supported in the θ direction. The linear motor 101 has magnets 103, 104 magnetized in the thickness direction.
It is composed of magnetic material yokes 105 and 106, coils 107 and 108, and a bobbin 109 around which these coils 107 and 108 are wound. The yokes 105 and 106 are arranged so as to face the magnets 103 and 104, respectively, and these yokes 105 and 106 are provided with a pair of through holes 11 formed in the bobbin 109.
It is inserted through 0 and 111. At least the outer peripheral portion of the bobbin 109 may be made of a non-magnetic material, and the central portion may be formed of a metal such as aluminum. The bobbin 109 is formed with L-shaped holes 112 V and 112 H between a pair of through holes 110 and 111 formed in the bobbin 109, and the optical path is changed at the intersection of these holes 112 V and 112 H. Fix the reflector 113 for use. On the exit side of the hole 112 V facing the optical disc 102, an optical pickup 116 having an objective lens 115 is attached via a mount 114, while a reading optical system 117 is arranged in the direction in which the hole 112 H is extended. Reading optics
117 is a laser diode 118 and a beam splitter 119
, A collimator lens 120, a light receiving optical system 121, a photodiode 122, and the like. The light emitted from the laser diode 118 is reflected by the reflecting mirror 113 via the collimator lens 120, is incident on the optical disc 102 via the optical pickup 116, is reflected here, and is further reflected by the optical pickup 116 and the reflecting mirror 113. Through the collimator lens 120, the optical path is changed by the beam splitter 119, the light enters the photodiode 122, and the information recorded on the optical disc 102 is read.

[0004]

The electromagnetic driving device used to move the optical pickup means such as the objective lens in the optical reproducing device is required to have high driving sensitivity and small size. . Further, it is desirable that resonance does not occur during driving. That is, in the electromagnetic drive device shown in FIG. 9 and FIG. 10, the center F of the force generated in the coils 107 and 108 when viewed from the X direction and the center of gravity G of the movable portion of the linear motor 101 match. Is desirable. The center F of this force and the center of gravity G of the movable part are, for example, Z
If the movable portion is displaced in the X direction, a moment around the Y axis is generated in the movable portion when the movable portion is moved in the X direction.
Resonance will be induced around the axis.

As is apparent from FIGS. 9 and 10, in such an electromagnetic drive device, the movable portion of the linear motor 101 has an optical pickup 11 located above the coils 107 and 108.
Since the load such as 5 and the magnetic head is positioned, Z
It is necessary to add counterbalance to the side opposite to these loads in the direction, or to add meat to the Z (−) side of the bobbin 109.

For this reason, there is a problem in that the entire movable portion of the linear motor 101 becomes heavy and the drive sensitivity of the electromagnetic drive device is lowered. In addition, there is a problem that the movable portion becomes thicker because the counter balance is attached, which does not meet the purpose of downsizing. Since the coils 107 and 108 have the optical disk 102 and the cartridge (not shown) thereabove, the positions of the coils 107 and 108 cannot be raised.

[0007]

In order to solve the above-mentioned problems, an electromagnetic drive device of the present invention comprises a movable part having at least one coil, a first magnetic member located in the coil, An electromagnetic drive device comprising: a second magnetic member arranged at a position forming a magnetic gap with the first magnetic member, wherein at least a part of the coil is located in the magnetic gap. The center of the magnetic surface of the first magnetic member is displaced from the center of the magnetic surface of the second magnetic member in a direction orthogonal to the direction of the force generated in the coil. Is.

Further, the electromagnetic drive device of the present invention includes a movable portion having at least one coil, a first magnetic member positioned in the coil, and a magnetic gap between the first magnetic member. And a second magnetic member arranged at a position where the center of the magnetic surface of the second magnetic member is located at the center of the magnetic surface of the second magnetic member. , With respect to the center of the portion of the coil located in the magnetic gap,
It is characterized in that it is displaced in a direction orthogonal to the direction of the force generated in the coil.

As described above, in the electromagnetic drive device of the present invention,
The center of the magnetic surface of the first magnetic member with respect to the center of the magnetic surface of the second magnetic member is displaced in the direction orthogonal to the direction of the force generated in the coil, or is located in the magnetic gap of the coil. Since the center of the magnetic surface of the second magnetic member with respect to the center of the portion is displaced in the direction orthogonal to the direction of the force generated in the coil, this electromagnetic drive device is applied to an information recording / reproducing device to move upward. When an optical pickup, a magnetic head, or the like is mounted, the counter balance attached below is reduced, or such counter balance becomes unnecessary, and the device is downsized.
The weight can be reduced. In addition, driving sensitivity can be improved.

Further, in the electromagnetic drive device of the present invention, there is provided a movable portion having at least one coil, a first magnetic member located in the coil, and a magnetic gap between the first magnetic member. And a second magnetic member disposed at a position for forming an electromagnetic drive device, wherein at least a part of the coil is located in the magnetic gap, the electromagnetic drive device is applied to a disk recording / reproducing device. In this case, at least a part of each of the first magnetic member, the second magnetic member, and the coil forming the electromagnetic drive device is located inside the opening of the disk cartridge for housing the disk. It is characterized by that.

As described above, according to the present invention, when the electromagnetic drive device is applied to a magneto-optical disc recording / reproducing device or the like to record / reproduce information, the opening of the disc cartridge accommodating the magneto-optical disc or the like. Part of the first magnetic member, the second magnetic member, the coil, and the like can be allowed to enter the inside of the unit, so that the electromagnetic drive device as a whole can be made compact and thin, and the recording / reproducing device can be made compact. It can also be made thinner.

[0012]

1 to 6 are views showing the configuration of a first embodiment of an electromagnetic drive apparatus of the present invention applied to a recording / reproducing apparatus for a magneto-optical disk. 1 is a perspective view showing the overall configuration of the electromagnetic drive device, FIG. 2 is an exploded perspective view showing the configuration of the movable portion of the electromagnetic drive device, FIG. 3 is a sectional view of the device shown in FIG. 1 in the X direction, and FIG. Is a perspective view showing an actuator configuration of an optical pickup mounted on an electromagnetic drive device, FIG. 5 is an exploded perspective view of the actuator, and FIG. 6 is an exploded perspective view of the actuator shown in FIG. 5 when viewed from below.

As shown in FIG. 1, in the electromagnetic drive apparatus of the present invention, a spindle motor 2 is fixed on a deck base 1, and a magneto-optical disk 3 is rotatably supported by the spindle motor 2. . On the deck base 1, a movable portion 4 including an actuator 22 described later is supported so as to be movable in the X direction.

The detailed structure of the movable portion 4 is as shown in FIG. That is, a carriage 20 made of aluminum die casting is provided, and an actuator 22 is arranged on the spindle motor side of the carriage 20 by three screws 21, 21, 21. In addition, a mirror 45 is mounted in the annular recess 20 a of the carriage 20 so as to be located directly below the objective lens 40. As shown in FIG. 1, a fixed optical system 5 is provided behind the carriage 20 on the opposite side of the spindle motor. A light emitting element and a light receiving element (not shown) are provided in the fixed optical system 5, and the light beam emitted from the light emitting element is taken into the movable portion 4 and reflected by the mirror 45 to be reflected by the objective. The light incident on the magneto-optical disk 3 through the lens 40 and reflected by the magneto-optical disk 3 is re-mirrored.
It is reflected by 45 and guided to the light receiving element in the fixed optical system 5.

The opposite side of the spindle motor of the carriage 20 rises upward, and one end of a spring 23 is fixed to the upper side surface 20c of the rising portion 20b by two screws 24, 24. At the other end of the spring 23, a slider 26 having a field coil 25 for generating a magnetic field on the information recording surface of the magneto-optical disk 3 is fixed. The slider 26 is designed to float above the rotating magneto-optical disk 3 in a small amount. Since it is necessary to sandwich the magneto-optical disk 3 between the objective lens 40 and the slider 26, the length of the spring 23 in the X direction and the upper side surface of the rising portion 20b of the carriage 20.
The length in the X direction between 20c and the objective lens 40 must be sufficiently long.

When information is recorded on the magneto-optical disk 3 by using magnetic field modulation, the field coil 25 needs to be downsized in order to reduce the inductance of the field coil 25. Therefore, the effective magnetic field range of the magnetic field generated by the field coil 25 is also
For example, it becomes small at about 150 μm square. Therefore, it is necessary to reduce the positional deviation between the light spot of the objective lens 40 and the field coil 25.

Usually, in the magneto-optical disk device, the temperature is
It changes from 5 ℃ to 60 ℃. Here, considering a case where the distance from the light spot formed by the objective lens 40 to the screw 24 for fixing the spring 23 is 30 mm and the temperature inside the magneto-optical disk device changes 55 ° C. from 5 ° C. to 60 ° C., the objective is The deviation between the light spot formed by the lens 40 and the field coil 25 is such that the linear expansion coefficient of aluminum, which is the material of the carriage 20, is 23.6 × 10 ⁻⁶ / ° C., and the wire of chrome nickel stainless steel, which is the material of the spring 23. When the expansion coefficient is 17.3 × 10 ^-6 / ° C, it becomes 10 μm. Such a deviation is within 10% of the effective magnetic field range of the magnetic field generated by the field coil 25, which is within 10% of the effective magnetic field range of 150 μm.

When chrome stainless steel is used as the material of the spring 23, the linear expansion coefficient α of chrome stainless steel is 9 ×
Since it is about 10 ^-6 / ° C, the objective lens 40 and field coil 25
The deviation from and becomes as large as 24 μm. Therefore,
If you use aluminum die-cast for the carriage 20,
Since the linear expansion coefficient of chrome-nickel stainless steel is closer to that of aluminum than the linear expansion coefficient of chrome-stainless steel, the method of using chrome-nickel stainless steel for the material of the spring 23 is preferable. Even when the carriage 20 and the spring 23 are made of other materials, it is preferable to combine the carriage 20 and the spring 23 having linear expansion coefficients as close as possible (for example, the difference in linear expansion coefficient is within 30%).

A cover 22a for covering the actuator 22 is further fixed on the carriage 20. Carriage 20
U-shaped recesses 20d, 20d on both sides in the Y direction
The coils 27, 27 wound in a tetrahedral shape are fixed to the recesses 20c, 20c, respectively. As shown in FIG. 1, center yokes 6, 6 are inserted into the coils 27, 27, and the center yokes 6, 6 are fixed to the deck base 1 by screws 7, 7, 7, 7, respectively. The center yokes 6, 6 are in contact with substantially U-shaped side yokes 8, 8 which are also fixed to the deck base 1 by screws 9, 9. Magnets 10 and 10 magnetized in the thickness direction are fixed inside the side yokes 8 and 8. The magnets 10 and 10 and the center yokes 6 and 6 are fixed.
A magnetic gap is formed between Coils 27, 27
When a current is passed through, a force is generated in the X direction on one side of the coils 27, 27 located in the portion where the magnetic gap is formed, and the movable portion 4 moves in the X direction.

One end 28a of the FPC 28 is fixed to the lower surface of the carriage 20, the FPC 28 extends in the Y direction via a bent portion 28b, and the other end 28c is fixed on the deck base 1. There is. The FPC 28 is arranged such that its bent portion 28b is located between the movable portion 4 and the spindle motor 2, and therefore does not interfere with the light beam emitted from the fixed optical system 5. The FPC 28 makes electrical connection to the coil 27 and the actuator 22. Further, one end of another FPC 29 is attached to the side surface 20e of the rising portion 20b of the carriage 20. An L-shaped plate 30 is fixed to the other end of the FPC 29, and this plate 30 is shown in FIG.
It is fixed to the fixed optical system 5 as shown in FIG. This FP
AE for detecting an abnormality in the field coil 25 and the slider 26 or the slider 26 attached to the spring 23 via C29
An electrical connection with a sensor (not shown) is made. Since the FPC 29 is arranged above the light flux emitted from the fixed optical system 5, it does not interfere with the light flux.

At the other end 29a of the FPC 29, an electric circuit 31 including a circuit for driving the field coil 25 and a preamplifier circuit for an AE sensor (not shown) is provided. Therefore, the distance between the field coil 25 or the AE sensor (not shown) and the electric circuit 31 is short, and noise is less likely to occur. Moreover, the mass of the entire movable portion 4 is also reduced. If the drive sensitivity of the movable part 4 has a margin, this electric circuit 31
Is disposed at the end portion 29b of the FPC 29 on the carriage 20 side, it is possible to further suppress the generation of noise.

Two bearing mounting portions 20f are provided at one end of the carriage 20 in the Y direction. The outer rings are respectively V-shaped on the mounting portions 20f and 20f.
The shafts of the character-shaped bearings 32, 32 are press-fitted. Also,
At the other end of the carriage 20 in the Y direction, a bearing mounting portion 20g for mounting a bearing diagonally
An outer ring press-fits the shaft of a cylindrical bearing 33 into the mounting portion 20g. This bearing 33
Is an angle δ formed by the axis 33a and the XY plane as shown in FIG.
Is greater than 45 ° (eg 50 °). A preload spring 35 is attached to the lower side of the mounting portion 20g of the carriage 20 via a screw 35a, and an outer ring press-fits a cylindrical bearing 36 at the tip of the preload spring 35.

As shown in FIG. 1, the center yokes 6, 6
Reference guide rails 11a and 11b are fixed to the deck base 1 by two salvis 12a, 12a, 12b and 12b, respectively. The guide rails 11a and 11b are slidably inserted into openings 20h provided in the Y direction of the carriage 20, respectively. The guide rail 11a on the reference side is 2
It is in contact with the V-shaped outer ring of two bearings 32, 32,
The outer ring of the bearing 33 is in contact with the driven guide rail 11b, and the bearing 36 is in contact with the guide rail 11b while applying a preload. In this way, the movable part 4 has four bearings 3
It is movably supported in the X direction by 2, 32, 33, 36 and two guide rails 11a, 11b.

As shown in the sectional view of FIG. 3, comparing the heights of the two guide rails 11a and 11b in the Z direction, it can be seen that the driven guide rail 11b is higher by Z ₁ . The midpoint S of the line connecting the centers of the two guide rails 11a and 11b is the objective lens when viewed from the X direction.
It is on the optical axis of 40. The guide rails 11a and 11b are arranged so as to be displaced in the Z direction by applying a load in the thrust direction to the bearings 32 and 32 which are in contact with the guide rail 11a on the reference side, so that the play of the bearings 32 and 32 themselves is prevented. It is to lose it. The bearing 33 that is in contact with the guide rail 11b on the driven side is high because it is high in the Z direction.
The position in the Z direction also becomes higher, and the upper end thereof approaches the magneto-optical disk 3, but in this embodiment, as described above, the bearing 33 is tilted at an angle of 50 ° with respect to the XY plane at 45 °. The tilted arrangement prevents the upper end from approaching the magneto-optical disk 3.

Further, as shown in FIG. 2, since the bearings 33 and 36, which are in contact with the guide rail 11b on the driven side, are arranged at positions displaced in the X direction with respect to the actuator 22, these bearings are arranged. The bearing can be positioned closer to the center in the Y direction, and as a result, the dimension of the entire movable portion 4 in the Y direction can be reduced, and the weight of the movable portion 4 can be reduced. Also, bearings 33, 36
Since the bearing 33 can be located in the opening 3b of the cartridge 3a of the magneto-optical disk 3, as shown in FIG. 3, the bearing 33 and the cartridge 3a are separated from each other in the Y direction. Interference can be prevented. Further, a reference-side guide rails 11a, Z-direction displacement of the driven-side guide rail 11b, while ensuring Z _1, will be closer to the midpoint S of the guide rails to the magneto-optical disk 3 side, the movable portion 4 The dimension in the Z direction can be reduced.

Further, the center in the Z direction of the magnets 10, 10 brought into contact with the side yokes 8, 8 is the center of the center yokes 6, 6, the side yokes 8, 8 and the coils 27, 27 in the Z direction. It is higher by Z ₂ . Therefore, the magnetic flux density center f of the magnetic flux acting on the coils 27, 27 in the magnetic gap existing between the center yokes 6, 6 and the magnets 10, 10 is approximately the center of the center yoke 6 in the Z direction. It exists at a position as high as Z ₂ × 1/2. The center f of this magnetic flux density is one coil
It is the driving center of the driving force in the X direction generated in 27 and is the driving center F of the driving force in the X direction generated in the two coils 27, 27.
Is on the optical axis of the objective lens 40 when viewed from the X direction, as shown in FIG. 3, and is at the midpoint S of the guide rails 11a and 11b.
Is consistent with The center of gravity G of the movable part 4 is also the coil.
It coincides with the driving center F of 27, 27. As described above, in the present invention, the height of the drive center F of the coils 27, 27 in the Z direction is determined by the center yoke 6, the 6 side yokes 8,
8. Height of the coils 27, 27 in the Z direction and the magnet 1
Compared to the case where the heights of 0 and 10 are the same, Z ₂ × 1
Only / 2 can be brought closer to the magneto-optical disk 3 side.

Since the height of the drive center F is closer to the magneto-optical disk 3 than the center of the coils 27, 27 in the Z direction, the coils 27, 27 themselves can act as a balancer. Therefore, since the actuator 22, the spring 23, etc. are located closer to the magneto-optical disk 3 side than the drive center F, the mass of the balancer required to match the center of gravity of the movable portion 4 with the drive center F is small. Or it is possible to eliminate the balancer. As a result, it is possible to reduce the weight of the movable portion 4 as a whole to increase the driving sensitivity, and also to reduce the thickness of the movable portion 4 in the Z direction to reduce the size of the entire apparatus.

In this embodiment, the reference side guide rail
Since two outer ring-shaped bearings 32, 32 are used as the bearings to be brought into contact with 11a,
The number of bearings can be reduced and the cost can be reduced as compared with the case where four cylindrical bearings are used. Further, bearings 33 and 36 each having an outer ring shape of a cylindrical shape are combined with the driven side guide rail 11b to preload the bearing 36. If the bearing on the driven side guide rail 11b has a V-shaped outer ring and this bearing is held by a preload spring to apply preload, the bearing is displaced due to external vibration or resonance of the preload spring. As a result, the movable portion 4 moves in an undesired direction. According to this embodiment, since the bearing 33 is fixed, the preload spring
Even if 35 resonates, the movable portion 4 hardly resonates.

Actuator with reference to FIGS. 4, 5 and 6.
22 will be described. 4 is a perspective view showing the overall structure of the actuator 22, FIG. 5 is an exploded perspective view of the actuator 22, and FIG. 6 is a diagram showing the exploded perspective view of FIG.

The objective lens 40 is fixed to the center of the lens holder 41. Recesses 41a, 41a are formed at both ends of the lens holder 41 in the Y direction, and focus coils 42, 42 wound in a quadrangular prism shape are disposed in the recesses 41a, 41a. The concave portions 41a, 41a are provided with a convex portion 41d protruding upward from both ends of the bottom surface 41b, the side surface 41c, and the bottom surface 41b in the X direction,
The bottoms of the focus coils 42, 42 are the bottoms of the recesses 41a, 41a.
The outer peripheral surface 3 is positioned and fixed to the side surface 41c by the side surface 41c, and the inner surface is fixed to the convex portion 41d. A tracking coil is provided on the remaining outer peripheral side surface of the focus coil 42.
43 and 43 are fixed respectively. These tracking coils 43, 43 are arranged offset from each other in the X direction. The convex portion 41d has a yoke 54, which will be described later.
It contacts the side surface of the lens holder 41 in the X direction and acts as a stopper in the X direction of the lens holder 41.

On the bottom surface of the lens holder 41, a U-shaped balancer 44 is fixed along the outer circumference of the holder. This balancer 44 is made of phosphor bronze plate. Figure 5
As shown in FIG. 2, arc-shaped convex portions 41e and convex portions 44a are formed on one side of the lens holder 41 and the balancer 44, respectively, and the light beam emitted from the fixed optical system 5 (see FIG. 1) is The mirror 45 (see FIG. 2) is passed directly below the convex portion 44a.
Incident). The balancer 44 is fixed so as to be substantially along the outer periphery of the bottom surface of the lens holder 41, so that the torsion rigidity around the X axis of the lens holder 41 is increased and the resonance frequency is increased. Further, the convex portion 41e formed on the lens holder 41 also acts to increase the rigidity of the lens holder 41. Also,
On the bottom side of the lens holder 41, a rectangular recess (41j) for installing the mirror 45 is formed, and the objective lens
40 and the mirror 45 are configured to come close to each other.

Projecting portions 41f and 41f are formed at both ends of the lens holder 41 in the X direction.
Grooves 41g, 41g are formed on both upper and lower surfaces of 41f, 41f, and one end portion 46a of each of the springs 46, 46, 47, 47 is formed in these grooves.
46a, 47a, 47a are fixed. One ends 46a, 46a, 47a, 47a of these springs are also directly soldered to the ends (not shown) of the focus coil 42 and the tracking coil 43. The other end 46 of the springs 46, 46, 47, 47
b, 46b, 47b, 47b are grooves 48a, 48a, 48b, 48b formed at both ends of the upper end of the holding member 48 in the X direction.
It is fixed to each by soldering. These grooves 48a, 48a, 48 of the holding member 48 made of plastic
A pattern is formed of copper on the back side of the b, 48b and the holding member 48 so that the springs 46, 46, 47, 47 are electrically connected. Therefore, the FPC is not required here, and the problem that the spring is stressed due to the deformation of the FPC can be prevented.

The springs 46, 46, 47, 47 are formed by etching a beryllium copper plate, and the dampers 49, 49, 4 are partially formed.
It is covered with 9,49. These springs 46, 46, 47, 47 hold the lens holder 41 movably in the X and Z directions. These springs 46, 46, 47, 47
Is bent inward in the X direction, and the left and right springs 46
And 47, the distance between the lens holder 41 side ends 46a, 46a;
47a, compared to the spacing of 47a, the end portion 46b on the holding member 48 side,
46b; 47b, 47b are configured to have a wide interval. With this configuration, the dimension in the X direction on the lens holder 41 side can be reduced, and the torsional rigidity around the Y axis can be increased.

Two bosses (not shown) are formed on the bottom surface of the holding member 48. The bosses are engaged with the holes 50a, 50a formed in the base 50 to hold the holding member 48 in the base 50. Position on top. A housing 48d is integrally formed with the holding member 48 via a connecting portion 48c. Housing 48d
A recessed portion 48e is formed in the recessed portion 48e, and when the actuator 22 is assembled, a flag 41h provided at one end of the protruding portion 41f of the lens holder 41 is located in this recessed portion 48e.
An LED 51 and a PD 52 are fixed inside the housing 48d, and the light receiving surface of the PD 52 is divided into two in the X direction. The light emitted from the LED 51 in the Y direction is the flag 41.
Since the central portion is shielded from light by h and enters the PD 52, the shadow of the flag 41h is on the dividing line of the PD 52. Therefore, the flag 41h, that is, the position information in the X direction of the objective lens 40 or the moving speed information can be obtained by taking the difference between the outputs of the light receiving surfaces of the PD 52.

The connecting portion 48c of the holding member 48 is composed of the upper and lower springs 4
Since it is located between 6 and 47, this connecting part 48c
The outer shape of the actuator 22 is not increased.

The springs 46, 46, 47 and 47 are assembled in a state where the lens holder 41 and the holding member 48 are positioned by using jigs. Also, the flag 41h of the lens holder 41
Is integrally molded with the lens holder 41, and the housing 48d is integrally molded with the holding member 48. Therefore, the LED 51, the PD 52,
The mutual positional accuracy of the flags 41h is improved, and an offset is unlikely to occur in the differential output of the PD 52. With this configuration, position adjustment work during assembly is unnecessary. Further, the position sensor section of the objective lens 40 (flags 41h, L
(ED51, PD52) is located on the opposite side of the fixed optical system 5 with respect to the mirror 45, so that the light flux between the mirror 45 and the fixed optical system 5 does not interfere, and the position sensor section can be easily arranged. is there.

The base 50 is formed by press molding a single iron plate. Four yokes 53, 53, 54, 54 extending in the X direction
Stands up in the Z direction, and magnets 55, 56 magnetized in the thickness direction are fixed to the inner side surfaces of the outer yokes 53, 53 with the N pole inside. A magnetic gap is formed between the magnets 55 and 56 and the inner yokes 54 and 54. One side portion of the outer yokes 53 in the X direction is bent inward to form a yoke 53a. As shown in FIG. 4, when the actuator 22 is assembled, the sides 43a, 43a of the tracking coil 43 face the magnets 55, 56, respectively, and the sides 43b, 43 of the other side.
b is a position facing the yokes 53a, 53a, respectively. The direction of the magnetic flux in the magnetic gap is opposite in the Y direction between the one side 43a of the tracking coil 43 and the other side 43b, so that the forces generated on these sides 43a and 43b are the same in the X direction. Turn to face. Further, one side of the focus coil 42 is also located in this magnetic gap, and a force is generated in the Z direction.

An FPC 55 is attached to the lower surface of the base 50, and the LED 5 passing through the holes 50b and 50b provided in the base 50.
1. Soldered to the terminals (not shown) of the PD 52 to electrically connect these elements. Further, one end of the base 50 in the X direction is bent upward at a right angle to form a reinforcing portion 50c, and the other end of the base 50 is formed with a light beam burr 50d whose lower side is cut in an arc shape. The light emitted from the fixed optical system 5 is incident on the mirror 45 after passing directly below 50d.

FIG. 7 is a diagram showing the configuration of the second embodiment of the present invention. In the following embodiments, only parts different from the first embodiment described above will be shown and described. The same components as those in the first embodiment are designated by the same reference numerals.

In the second embodiment, the side yoke 8 and the magnet 10 are located in the coil 27, and the center yoke 6
Was arranged outside the coil 27. In this embodiment, the center of the center yoke 6 in the Z direction is arranged to be higher by Z ₂ than the height of the center of the magnet 10 and the coil 27 in the Z direction. Therefore, the height of the drive center f of the drive force generated in the coil 27 can be increased by about Z ₂ × 1/2.

FIG. 8 is a diagram showing the configuration of the third embodiment of the present invention. Here, a guide rail that instructs the movable portion 4
Among the guide rails 11a and 11b, the guide rail 11a on the reference side has a V-shaped outer ring press-fitted into the lower end of the carriage 20 in the Y direction, and the driven ring also has a V-shaped bearing 60 on the driven side. It is fixed to the spring and attached to the carriage 20. Notch 61 at one corner of the center yoke 61, 61
a, and guide rails are formed in the notches 61a and 61a.
Position 11a and 11b respectively. The notch 61a of the reference-side center yoke 61 is formed on the lower side, and the notch 61a of the driven-side center yoke 61 is formed on the upper side.
The positions of a and 11b are made different in the Z direction. The coils 27, 27 are located around the center yokes 61, 61 and the guide rails 11a, 11b. Coils 27, Y of 27
Side yokes 62, 62 are arranged on the outer side in the direction, and the magnet 1 is arranged inside the side yokes 62, 62.
0 and 10 are stuck. These members are coils 27, 27
Further, the centers of the magnets 10, 10 in the Z direction are arranged to be higher by Z ₂ than the centers of the center yokes 61, 61 in the Z direction. Also, the side yoke 6
As shown in FIG. 8, the tips of the reference numerals 2 and 62 are folded inward, and the magnets 10 are fixed to the rising portions 62a and 62a.

As described above, in this embodiment, the center yokes 61 and 61 and the guide rails 11a and 11b are connected to the coil 2.
Two side yokes 6 because they are located in 7 and 27
The interval between the rising portions 62a, 62a of 2, 62 in the Y direction can be shortened, and the portion from the side yoke 62 to the side yoke 62 of the drive device is located in the opening 3b of the cartridge 3a. That is, a part of the driving means and a part of the bearing 60 and the supporting means of the guide rail 11b are located in the opening 3b of the cartridge 3a. Therefore, the magnets 10, 10 and the coils 27, 27 can be brought closer to the magneto-optical disk 3 and the counter balancer or the like can be made smaller or eliminated, and the entire device can be made thin. Can be small.

In the above-described embodiments, the example in which the electromagnetic drive device of the present invention is applied to the recording / reproducing device of the magneto-optical disk has been described. However, in addition to this, the optical disk device and the magnetic disk device having the magnetic head are also used. It goes without saying that the present invention can be applied.

[0044]

As described above in detail, in the electromagnetic drive device of the present invention, the center of the coil or the magnetic member facing the magnetic member passing through the coil is increased in the Z direction. Can be easily increased. Therefore, it is possible to reduce the balancer attached to the movable portion of the drive device, the actuator, or the like, or to eliminate the balancer, and it is possible to provide an electromagnetic drive device with high drive sensitivity. Further, when the electromagnetic drive device of the present invention is applied to a magneto-optical disk recording / reproducing device, an optical pickup, a magnetic head, etc. mounted on the drive device can be housed within the height of the coil. A part of the constituting magnetic member and coil can be inserted into the opening of the disk cartridge. Therefore, not only can the electromagnetic drive device be miniaturized and thinned, but also the recording / reproduction device can be miniaturized and thinned.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of a first embodiment of an electromagnetic drive device according to the present invention.

FIG. 2 is an exploded perspective view of a movable part of the device shown in FIG.

FIG. 3 is a cross-sectional view in the Y direction of the device shown in FIG.

FIG. 4 is a diagram showing a configuration of an actuator of the device shown in FIG.

5 is an exploded perspective view of the actuator shown in FIG.

6 is an exploded perspective view of the actuator shown in FIG. 5 viewed from the opposite side.

FIG. 7 is a diagram showing a partial configuration of a second embodiment of the electromagnetic drive device according to the present invention.

FIG. 8 is a diagram showing a partial configuration of a third embodiment of the electromagnetic drive device according to the present invention.

FIG. 9 is a perspective view showing a configuration of a conventional electromagnetic drive device.

FIG. 10 is a cross-sectional view of the electromagnetic drive device shown in FIG. 9 taken along the line −.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Deck base 2 Spindle motor 3 Magneto-optical disk 3a Cartridge 3b Opening 4 Moving part 5 Fixed optical system 6 Center yoke 8 Side yoke 10 Magnets 11a, 11b Guide rail 20 Carriage 22 Actuator 23 Spring 25 Field coil 27 Coil 28, 29 FPC 32, 33, 36 Bearing 35 Leaf spring 40 Objective lens 41 Lens holder 42 Focus coil 43 Tracking coil 44 Balancer 46, 47 Spring 48 Holding member 50 Base 51 LED 52 PD 53, 54 Yoke 55 FPC 60 Bearing 61 Center yoke 62 Side yoke

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[Procedure amendment]

[Submission date] March 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

The electromagnetic driving device used to move the optical pickup means such as the objective lens in the optical reproducing device as described above is required to have high driving sensitivity and small size. . Further, it is desirable that resonance does not occur during driving. That is, in the electromagnetic drive device shown in FIG. 9 and FIG. 10, the center F of the force generated in the coils 107 and 108 when viewed from the X direction and the center of gravity G of the movable portion of the linear motor 101 match. Is desirable. The center F of this force and the center of gravity G of the movable part are, for example, Z
If the movable portion is displaced in the X direction, a moment about the Y axis is generated in the movable portion when the movable portion is moved in the X direction.
Resonance will be induced around the axis.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Further, in the electromagnetic drive device of the present invention, there is provided a movable portion having at least one coil, a first magnetic member located in the coil, and a magnetic gap between the first magnetic member. And a second magnetic member disposed at a position for forming an electromagnetic drive device, wherein at least a part of the coil is located in the magnetic gap, the electromagnetic drive device is applied to a disk recording / reproducing device. In this case, at least a part of the first magnetic member, the second magnetic member, or the coil that constitutes the electromagnetic drive device is located inside the opening of the disc cartridge that accommodates the disc. It is a feature.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

As shown in FIG. 1, the center yokes 6, 6
Reference guide rails 11a and 11b are fixed to the deck base 1 by two salvis 12a, 12a, 12b and 12b, respectively. The guide rails 11a and 11b are movably inserted in openings 20h provided in the Y direction of the carriage 20, respectively. The guide rail 11a on the reference side is 2
It is in contact with the V-shaped outer ring of two bearings 32, 32,
The outer ring of the bearing 33 is in contact with the driven guide rail 11b, and the bearing 36 is in contact with the guide rail 11b while applying a preload. In this way, the movable part 4 has four bearings 3
It is movably supported in the X direction by 2, 32, 33, 36 and two guide rails 11a, 11b.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

An FPC 55 is attached to the lower surface of the base 50, and the LED 5 passing through the holes 50b and 50b provided in the base 50.
1. Soldered to the terminals of PD52 to establish electrical connection between these elements. Also, one end of the base 50 in the X direction is
It is bent upward at a right angle to form a reinforcing portion 50c, and the other end has a light beam burr 50 whose lower side is cut in an arc shape.
d is formed, and the light emitted from the fixed optical system 5 is incident on the mirror 45 after passing through just below this luminous flux 50d.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

As described above, in this embodiment, the center yokes 61 and 61 and the guide rails 11a and 11b are connected to the coil 2.
Since the side yokes 62, 62 arranged in 7, 27 have a sectional area other than the fixed portions of the magnets 10, 10, the fixed portions of the side yokes 62, 62 for the magnets 10, 10 are thin. For this reason, the interval between the rising portions 62a, 62a of the two side yokes 62, 62 in the Y direction can be shortened, and the portion from the side yoke 62 to the side yoke 62 of the drive device can be placed in the opening 3b of the cartridge 3a. I am trying to position it. That is, a part of the driving means and a part of the bearing 60 and the supporting means of the guide rail 11b are located in the opening 3b of the cartridge 3a. Therefore, the magnets 10, 10 and the coils 27, 27 can be brought closer to the magneto-optical disk 3 and the counter balancer or the like can be made smaller or eliminated, and the entire device can be made thin. Can be small.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044]

As described above in detail, in the electromagnetic drive device of the present invention, the center of the coil or the magnetic member facing the magnetic member passing through the coil is increased in the Z direction. Can be easily increased. Therefore, it is possible to reduce the balancer attached to the movable portion of the drive device, the actuator, or the like, or to eliminate the balancer, and it is possible to provide an electromagnetic drive device with high drive sensitivity. When the electromagnetic drive device of the present invention is applied to a magneto-optical disc recording / reproducing device using a disc cartridge, a magnetic member and a part of the coil constituting the electromagnetic drive device are positioned in the opening of the disc cartridge. Configured to. Therefore, not only can the electromagnetic drive device be miniaturized and thinned, but also the recording / reproduction device can be miniaturized and thinned.

Claims (3)

[Claims] 1. A movable part having at least one coil, a first magnetic member positioned in the coil, and a first magnetic member disposed at a position forming a magnetic gap between the first magnetic member and the first magnetic member. 2 is a magnetic member, wherein at least a portion of the coil is located in the magnetic gap, the center of the magnetic surface of the first magnetic member is the second magnetic member. An electromagnetic drive device, wherein the magnetic drive surface is displaced from the center of the magnetic surface in a direction orthogonal to the direction of the force generated in the coil. 2. A movable part having at least one coil, a first magnetic member positioned in the coil, and a first magnetic member disposed at a position forming a magnetic gap between the first magnetic member and the first magnetic member. An electromagnetic drive comprising at least a part of the coil located in the magnetic gap, wherein the center of the magnetic surface of the second magnetic member is in the magnetic gap of the coil. The electromagnetic drive device is characterized in that it is displaced in a direction orthogonal to the direction of the force generated in the coil with respect to the center of the portion located at. 3. A movable part having at least one coil, a first magnetic member positioned in the coil, and a first magnetic member disposed at a position forming a magnetic gap between the first magnetic member and the first magnetic member. 2. An electromagnetic drive device comprising two magnetic members, wherein at least a part of the coil is located in the magnetic gap, when the electromagnetic drive device is applied to a disk recording / reproducing device, the electromagnetic drive device. At least a part of each of the first magnetic member, the second magnetic member, and the coil configuring the above is configured so as to be located in the opening of the disc cartridge that accommodates the disc. .