JP3234061B2 - Optical system drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system driving apparatus provided in an optical recording / reproducing apparatus for optically recording / reproducing data on a disk-shaped recording medium.

[0002]

2. Description of the Related Art In order to access a desired track of a disk-shaped recording medium (hereinafter simply referred to as a "disk"), a carriage of an optical system driving device is supported so as to be movable in a substantially radial direction of the disk. As this support means,
When a guide rail and a slide bearing formed on the carriage so as to be in contact with the guide rail are used, the optical system driving device can be reduced in size, weight and cost because of its simple structure.

However, the diameter of the slide bearing is slightly larger than the diameter of the guide rail so that the carriage can move while sliding with respect to the guide rail, and there is always a gap.

[0004] Normally, the sliding bearing is urged downward to contact the guide rail by the gravity of the carriage and various members mounted on the carriage (hereinafter, these are collectively referred to as "movable parts"). ing. However, when the carriage moves to the vicinity of the outer peripheral end of the disk and comes into contact with the movement limiting stopper provided on the optical system driving device so as to restrict the runaway of the carriage, or when external vibration occurs, the movable portion is moved. A force exceeding the urging force due to its own weight is easily generated, and the carriage moves in a direction other than the radial direction of the disk by an amount corresponding to the gap between the slide bearing and the guide rail. At this time, the end of the slide bearing collides with the guide rail, and both of them are damaged.

Further, in order to reduce the weight of the movable part, a separation optical system in which optical components mounted on the carriage are minimized, such as an objective lens, and the remaining light-emitting portion and light-receiving portion are mounted on a fixed portion. Is adopted, the optical path is deviated due to the contact between the carriage and the stopper or the external vibration, and the servo is dislocated.

Therefore, in order to always properly move the carriage in the access direction, a means for applying a biasing force to the bearing other than by the weight of the movable portion so as to withstand general external vibrations and the like. Is required.

[0007]

An optical system driving device having such an urging means is disclosed in, for example, Japanese Utility Model Application Laid-Open No. 61-4 / 1986.
No. 0771 is known.
In this device, as shown in FIG. 11, a carriage 2 is supported by a slide bearing 4 so as to be movable along a guide rail 6. A rotatable arm 10 having a ball bearing 8 at the tip is attached to the carriage 2. The arm 10 has a ball bearing 8
Are urged by a coil spring 12 in the direction of arrow A so as to contact the guide rail 6.

This device requires members such as the ball bearing 8, the arm 10, and the coil spring 12 in addition to the slide bearing 4, so that a simple configuration of the combination of the slide bearing and the shaft cannot be fully utilized, and the number of parts is reduced. Increase, and increase in the mass of the movable part.

In the apparatus disclosed in Japanese Utility Model Publication No. 59-71471, as shown in FIG. 12, a magnet 16 is mounted on the lower surface of a carriage 14, and a magnet 16 is provided between a deck base 18 made of a magnetic material and the magnet 16. The carriage 14 is urged toward the deck base 18 by generating a suction force. Further, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 3-5971, as shown in FIGS. 13 and 14, although a sliding bearing is not used, a magnet 22 is provided on the carriage 20 and is formed of a magnetic material. The carriage 20 is urged toward the guide rail 24 by sucking the guide rail 24.

In the two devices shown in FIGS. 12 to 14, the only component newly mounted on the carriage is a magnet. However, since the magnet is made of metal, it is still disadvantageous in terms of increasing the mass of the movable part. Further, since the magnet is expensive, it becomes an expensive device.

The apparatus disclosed in Japanese Patent Laid-Open No. 4-149829 does not use a slide bearing as shown in FIG. 15, but has a magnetic circuit for driving the carriage 26 along the guide rail 28. The carriage 26 formed of a magnetic material is attracted to the guide rail 28 by using the formed magnet 30.

According to such a configuration, it is not necessary to newly provide a component for urging the carriage 26 against the guide rail 28, so that the number of components does not increase. However, while the magnet 30 is fixed to a housing (not shown) of the apparatus, the movable portion 32 including the carriage 26 attracted by the magnet 30 moves along the guide rail 28. As a result, the size and direction of the magnetic flux generating magnet 30 or colleagues, carriage 26 differs between when away from the magnet 30 when it is directly above the magnet 30. In other words, the magnitude and direction of the attraction force by the magnet 30 are
8 depends on the position of the carriage 26. Therefore, it is difficult to apply a uniform and stable urging force to the carriage 26 over the entire moving range of the movable portion 32.

The present invention has been made in view of the circumstances of the prior art described above, and makes use of a support system having a simple structure of a slide bearing and a guide rail.
An object of the present invention is to provide an optical system driving device that stably urges a bearing against a shaft without increasing the number of parts.

[0014]

Accordingly, an optical system driving apparatus according to the present invention comprises an optical element, a carriage, a holder for holding an optical element, and a direction perpendicular to the recording surface of a disk-shaped recording medium and / or a disk-shaped medium. Supporting means for supporting the holder on the carriage so as to be movable in the radial direction of the recording medium; and fixing the holder to the holder in a direction perpendicular to the recording surface of the disk-shaped recording medium and / or in a radial direction of the recording medium. A coil to be moved, a magnet attached to the carriage and generating a magnetic field acting on the coil,
A sliding bearing provided on the carriage; and a plurality of guide rails contacting the sliding bearing so as to support the carriage so as to be movable in a radial direction of the recording medium, wherein at least one of the guide rails is provided. The book is characterized by being formed of a magnetic material so as to attract the carriage by the action of the magnetic flux of the magnet.

[0015]

The guide rail formed by the magnetic material receives such a force as to be attracted to the magnet by the action of the magnetic flux leaked by the magnet. As a result, the carriage is attracted to the guide rail, and rattling between the slide bearing formed on the carriage and the guide rail is eliminated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the optical system driving device according to the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 40 denotes an objective lens which is an optical element. The objective lens 40 is fixed to an upper part of a holder 42 formed in a substantially box shape. As shown in FIG.
The X ₂ side and X ₁ side of the convex portions 44a, 44b are formed. The Y ₂ sides and Y ₁ side of the holder 42, the recess 46a, 46b are formed.

Focus coils 48a and 48b wound around an axis extending in a direction parallel to the Z-axis are fixed to these concave portions 46a and 46b. Four tracking coils 50a to 50d wound around an axis extending in a direction parallel to the Y axis are fixed to each of the focus coils 48a and 48b.

The projections 44a and 44b of the holder 42
One end of each of the leaf springs 52a to 52d is fixed.
The other ends of these leaf springs 52a to 52d
It is fixed to the X ₁ side and X ₂ side of the. The leaf springs 52a to 52d are arranged in a direction (Z-axis direction) perpendicular to the recording surface 56a of the optical disk 56 shown in FIG.
The holder 42 is supported by the spring receiver 54 so as to be movable in the radial direction (X-axis direction).

[0019] The Y ₁ side of the portion of each of the leaf springs 52a to 52d, the vibration damping member 58a~58d consisting viscoelastic member coated like in aluminum foil in order to suppress the vibration is fixed. The four leaf springs 52a to 52d are provided with focus coils 48a and 48b and tracking coils 50a to 5d.
0d.

[0020] Y ₁ side of the spring bearing 54, the circuit board 6
0 is fixed. The other ends of the leaf springs 52a to 52d are soldered to the circuit board 60. The circuit board 60 is electrically connected to an electric circuit of the apparatus main body via a flexible board (not shown). Thus, the focus coils 48a and 48b and the tracking coils 50a to 50d are electrically connected to the electric circuit of the apparatus main body.

On the base 62 made of a magnetic material, two first inner yokes 64a and 64b and two first outer yokes 6
6a and 66b are provided upright. The spring receiver 54
The first outer yoke 66a of Y ₁ side, is fixed by screws or the like to 66b. Focus coil 48a, 4
8b is fixed to a focus coil 48.
The first inner yokes 64a, 64b are arranged on the base 62 such that the first inner yokes 64a, 64b are loosely inserted into the bases 62, 48b.

First magnets 68a, 68b are fixed to the inner surfaces of the first outer yokes 66a, 66b. First
Magnets 68a, 68b and first inner yokes 64a, 64b
Is provided with a predetermined interval. Since the base 62 is formed of a magnetic material, a magnetic circuit is formed by the first inner yokes 64a, 64b, the first outer yokes 66a, 66b, and the first magnets 68a, 68b. The distance between the first magnets 68a, 68b and the first inner yokes 64a, 64b is determined by the magnetic gap 70 shown in FIG.
a and 70b. Focus coil 48a,
One side of 48b is arranged so as to be located in the magnetic gaps 70a and 70b.

The base 62 and the first outer yokes 66a, 66
Openings 72a and 72b are formed in the connection portion with b. On the lower surface of the base 62, a spherical portion 74 is formed. A hole 76 for passing a light beam is formed in the bottom wall of the base 62 so as to penetrate the spherical portion 74.

The members described above, that is, the base 62 and various members provided on the base 62 are collectively referred to as a “lens driving unit” and are indicated by reference numeral 77. The base 62 is mounted on a carriage 78 made of synthetic resin. At a substantially central portion of the carriage 78, a spherical portion 74 of the base 62 is provided.
A spherical receiver 80 having substantially the same radius as the spherical part 74 is formed so as to conform to the above. The base 62 has a spherical surface 7
4 so that the carriage 7 is aligned with the spherical receiver 80.
8. The base 62 can be tilted on the carriage 78 by the engagement between the spherical portion 74 and the spherical receiver 80. The base 62 is releasably fixed to the base 62 by a screw (not shown) or the like.

As shown in FIG. 2, the bottom surface 8 of the spherical
2 is a plane. A groove 84 is formed in the carriage 78 so as to communicate with the bottom surface 82. A prism 86 that reflects the light beam is fixed to the groove 84. The prism 86 is located within the area of the spherical receiver 80. As a result, as shown in FIG. 3, the prism 86 enters the hole 76 of the base 62, and the objective lens 40 is positioned above the prism 86.

As shown in FIG. 2, Y _{2 of} the carriage 78
The side surfaces and Y ₁ side, access coil 88a is wound around an axis parallel to the X axis, 88b is fixed. These access coils 88a and 88b are connected to an electric circuit of the apparatus main body by a flexible substrate (not shown).

A main bearing 90 having a circular cross section and a driven bearing 92 having an elliptical cross section having a partially parallel portion penetrate through the carriage 78 on the Y ₁ side and the Y ₂ side in a direction parallel to the X axis. It is formed as follows. The Y _{2 of} the carriage 78 intersects with the main bearing 90 and the driven bearing 92.
The partial and Y ₁ side of the portion of the side openings 94a penetrating in the Z axis direction, 94b are formed. This opening 94
a and 94b are formed to reduce the weight of the carriage 78.

The main bearing 90 and the driven bearing 92 are formed integrally when the carriage 78 made of synthetic resin is formed, instead of fixing the bearing, which is a member separate from the carriage 78, to the carriage 78. A main bearing 90 and a driven bearing 92, and two guide rails 96a and 96 described later.
The synthetic resin used as the material of the carriage 78 is made of a material having a good slipperiness so that the contact member b can be in smooth contact.

The members described above, that is, the carriage 78
And the parts such as the lens driving unit 77 installed on the carriage 78 are collectively referred to as “movable parts” and are denoted by reference numeral 95. FIG.
As shown in the figure, guide rails 96a and 96b made of a magnetic material having good slipperiness, such as a magnetic material coated with a tetrafluoroethylene resin, are inserted through the bearings 90 and 92. The positions of these guide rails 96a and 96b are shown in FIG.
As shown in FIG. 5, the first outer yokes 66a, 66
6b of has become near the lower (Z ₂ side).

The diameter of each guide rail 96a, 96b is slightly smaller than the diameter of the main bearing 90 and the distance between the parallel portions of the cross section of the driven bearing 92 so that the carriage 78 can move freely in the X-axis direction. Is set. Since the driven bearing 92 has a parallel part, the driven part 92
It is possible to cope with an error in the interval between the guide rails 96a and 96b.

As shown in FIG. 1, the two access coils 88a and 88b are provided with second inner yokes 100a and 100 made of a magnetic material extending in a direction parallel to the X axis.
b is inserted. Second inner yokes 100a, 100
The two ends of the U-shaped second outer yokes 102a and 102b made of a magnetic material are connected to both ends of the b.
Second magnets 104a, 104b are fixed to the inner surfaces of the second outer yokes 102a, 102b. The second magnets 104a, 104b and the inner yokes 100a, 100b
Are provided at predetermined intervals so as to form magnetic gaps 106a and 106b. The access coils 88a, 88b are provided in the magnetic gaps 106a, 106b.
Of the access coils 88a, 88b
Is supplied with a magnetic field of the second magnets 104a and 104b.

The above-mentioned guide rails 96a and 96b,
The second inner yokes 100a, 100b and the second outer yokes 102a, 102b are fixed to a deck base (not shown).

The operation of the thus-configured optical system driving apparatus of the present embodiment will be described below. Figure 4 is a diagram showing a first magnet 68a located on the Y ₁ side, the distribution of 68b the magnetic field. In FIG. 4, the vector of the magnetic field in the space and the magnetic moment in the guide rail 96a are indicated by arrows.

As described above, the guide rail 96a made of a magnetic material is located near the lower part of the first outer yoke 66a to which the first magnet 68a is fixed. Therefore, the magnetic field generated by the first magnet 68a reaches the guide rail 96a. The direction of the magnetic field in the vicinity of the guide rails 96a is the upper left direction in FIG. 4 has a (Z ₁ direction and Y ₂ intermediate direction between a direction), the upper left direction accordingly also the direction of the magnetic moment of the guide rail 96a of a magnetic material Becomes As a result, the first
Between the magnet 68a and the guide rail 96a.

[0035] While the direction of the magnetic moment of the Y ₂ side of the guide rail 96a shown in FIG. 4 is a top left direction, the magnetic moment of the Y ₁ side of the guide rail 96b as shown in FIG. 3 the right upward (Z ₁ direction and Y ₁ Direction). Therefore, the first magnets 68a, 68b and the guide rails 96a, 96
Of the attraction force acting between is b, because the Y ₁ direction component force and Y ₂ direction component force cancel each other, the guide rail 9
The attraction force acting between the first and second magnets 6a and 96b and the first magnets 68a and 68b is directed upward as shown by reference numerals 108 and 110 in FIG. Since the guide rails 96a and 96b are fixed to a deck base (not shown), this attractive force is applied to the base 62 on which the first magnets 68a and 68b are mounted.
And the carriage 78 in contact with the base 62 are attracted toward the guide rails 96a and 96b.

Accordingly, the guide rails 96a, 96b, the driven bearing 92, and the main bearing 90 are connected to the guide rails 96a, 96.
Always contact at the upper surface or Z ₁ side part of b. Guide rails 96a, 96b and the gap between the driven bearing 92 and main bearing 90 the guide rails 96a, generated below i.e. Z ₂ side 96b (are highlighted a gap in FIG. 3) is the suction force 1
08 and 110, the guide rails 96a and 96b are always in contact with the driven bearing 92 and the main bearing 90, so that there is no play due to the gap. Thus, the movable portion 95 including the carriage 78 can be driven stably.

The openings 72a and 72b are formed between the first outer yokes 66a and 66b to which the first magnets 68a and 68b are bonded and the base 62, so that more magnetic flux than this portion is provided. Leaks, guide rails 96a, 96
The leakage magnetic flux reaching b is increased. If the attraction force due to the leakage magnetic flux is made larger than the external vibration, the servo will not be disconnected due to the vibration.

The laser beam emitted from the fixed optical block (not shown) with respect to the carriage 78 always held at the correct position as described above passes through the groove 84 shown in FIG. The objective lens 40 forms a spot on the recording surface 56a of the optical disk 56.

The reflected light from the recording surface 56a of the optical disk 56 is again transmitted to the objective lens 40, the prism 86, the groove 84
After that, the process returns to a fixed optical block (not shown), and a focus error, a tracking error, and a recording signal are detected.

When a focus error is detected, a current is applied to the focus coils 48a and 48b to move the holder 42 in a direction perpendicular to the recording surface 56a of the optical disk 56, that is, in the Z-axis direction. If a tracking error is detected, the tracking coils 50a to 50a-5
0d, the holder 42 is moved to the recording surface 56a.
In the radial direction, that is, in the X-axis direction.

As described above, the holder 42 and the holder 4
The focus control and tracking control of the objective lens 40 fixed to 2 are performed. When reading a different track, a current is supplied to the access coils 88a and 88b to move the movable section 95 including the carriage 78 and the objective lens 40, thereby controlling access.

Next, a second embodiment will be described with reference to FIGS. The members corresponding to those of the first embodiment are denoted by the same reference numerals, and only different portions will be described. In this embodiment, the spring receiver 54, the base 62, and the first
Inner yokes 64a, 64b and first outer yokes 66a,
66b.

In the first embodiment, the first outer yoke 6
Although 6a, 66b and first inner yokes 64a, 64b are formed integrally with the base 62, they are separate bodies in this embodiment. As shown in FIG. 6, the first inner yoke 64a and the first outer yoke 66a and the first inner yoke 64b and the first outer yoke 66b are integrally formed as U-shaped yoke portions 112a and 112b. Is formed. The yokes 112a and 112b are fixed on the base 62 with the open ends facing downward. As in the first embodiment, the guide rails 96a and 96b are located substantially below the first outer yokes 66a and 66b to which the first magnets 68a and 68b are fixed, as shown in FIG.

On the other hand, the base 62 is made of a magnetic material in the first embodiment, but in this embodiment, only the yoke portions 112a and 112b are made of a magnetic material, and the base 62 is made of a synthetic resin. Is formed.

In the first embodiment, the spring receiver 54 has a base 62.
In this embodiment, the base 62 and the base 62 are integrally formed of a synthetic resin. Other configurations are the same as those of the first embodiment.

The operation of the embodiment constructed as described above will be described below. As shown in FIG. 7, the U-shaped yoke portions 112a and 112b and the first magnet 68
Since the guide rails 96a and 96b made of a magnetic material are located near the lower part of the magnetic circuit formed by the a and 68b, the leakage flux from the magnetic circuit is reduced by the guide rail 96.
a, 96b. Here, the U-shaped yoke portion 112
Since the open ends of the a and 112b are directed toward the guide rails 96a and 96b, many magnetic fluxes of the magnetic circuit leak from the open ends, thereby increasing the leaked magnetic flux reaching the guide rails 96a and 96b. The base 6 is provided between the open ends of the yoke portions 112a and 112b and the guide rails 96a and 96b.
However, since the base 62 is made of a synthetic resin and is a non-magnetic material, the guide rails 96a and 96b
It does not hinder the leakage magnetic flux that reaches As a result, an attractive force acts between the guide rails 96a and 96b and the first magnets 68a and 68b, and forces such as arrows 114 and 116 shown in FIG. 7 act on the guide rails 96a and 96b. Other operations are the same as in the first embodiment.

According to this embodiment, there is no need to cut out the yoke and provide an opening, so that the strength of the yoke is increased.
Excellent resonance characteristics can be obtained. Since there is no yoke opening, it is easy to reduce the size of the yoke, and it is possible to obtain a small and lightweight optical system drive as a whole. The U-shaped yoke 11
The connection between 2a and 112b is on the optical disk 56 side. Therefore, it is possible to reduce the magnetic flux leakage to the optical disk 56 as the recording medium. The reduction of the leakage magnetic flux applied to the recording medium is particularly effective when the recording medium is a magneto-optical disk, and enables better recording and reproduction. Further, in this embodiment, the base is made of synthetic resin, and only a minimum amount of yoke necessary for forming a magnetic circuit is made of a magnetic material to reduce the weight.

Next, a third embodiment will be described with reference to FIGS. In this embodiment, unlike the first and second embodiments, as shown in FIG. 9, the objective lens 40 is provided on the Y ₁ end part of the holder 42 rather than the central portion of the holder 42. An opening 118 is formed in the center of the holder 42, and two tracking coils 50a and 50b and one focus coil 48 are bonded to the opening 118.

[0049] The X ₁ side and X ₂ side of the holder 42, a total of four convex portions 44a~44d are formed.
Two convex portions 44a of the Z ₁ side, 44c are arranged displaced two protrusions 44b of the Z ₂ side, relative to 44d to Y ₁ side.

The base 62 is formed integrally with the spring receiver 54 as in the second embodiment. X of this spring receiver 54
Also ₁ side and X ₂ side, the total in the same manner as the holder 42 four protrusions 55a~55d are formed. Two convex portions 55a of the Z ₁ side, 55c is, Z ₂ side of the two projecting portions 55b,
It is arranged displaced in the Y ₁ side of the 55d.

The projections 44a to 44d; 55a to 55
d, the interval between 44a and 55a, and 44b and 55b
, 44c and 55c, 44d and 55
The distance from d is set equal. With such a configuration, the lengths of the portions of the plate springs 52a to 52d that connect the two convex portions functioning as springs are equal, and there is no problem that the holder 42 is inclined when moving.

The projections 44a and 44c of the holder 42 are shifted with respect to the projections 44b and 44d, and
4 of the convex portion 55a, 55c and protrusion 55b, by staggered relative to 55d, when viewed lens driving unit 77 from the Z ₁ side, the convex portion 44a of the holder 42, 44c and the projections 44b, 44d does not overlap. As a result, the work of connecting the coil wires to the leaf springs 52a to 52d can be easily performed by the holder 42. The protruding portions are shifted from the protruding portions 55a to 55d of the spring receiver 54, but the leaf springs 52a to 52d overlap. However, wiring by a spring receiving 54 no problem is performed by the circuit board 60 from the Y ₁ side.

One U-shaped yoke 112 made of a magnetic material is attached to the base 62. The yoke portion 112, a first inner yoke 64 on the Y ₂ side, and has a first outer yoke 66 to Y ₁ side. Open end disc 56 of the yoke portion 112 (shown in FIG. 10) side (Z ₁ side)
It has become. The first inner yoke 6 of the yoke portion 112
A first magnet 68 is adhered to 4 to form a magnetic circuit. The space between the first magnet 68 and the outer yoke 66 forms a magnetic gap 70 as shown in FIG.

The holder 42 is supported by the base 62 so that one side of the focus coil 48 and the tracking coils 50a and 50b are located in the magnetic gap 70. A portion of the yoke portion 112 to which the first magnet 68 is fixed is partially notched, and the notched portion forms an opening 72.

As shown in FIG. 10, a spherical receiver 120 different from the spherical receiver 80 of the carriage 78 is formed on the base 62. This spherical receiver 120 has the same center as the spherical part 74. Hereinafter, the spherical receiver 80 of the carriage 78 is referred to as a “first spherical receiver 80”, and the spherical receiver 120 of the base 62 is referred to as a “second spherical receiver 120”.

The carriage 78 has a protrusion 122
Is formed on the lower surface of the protruding portion 122. The spherical portion 124 is different from the spherical portion 74 of the base 62. Hereinafter, the spherical portion 74 of the base 62 is referred to as a “first spherical portion 74”, and the spherical portion 124 of the protrusion 122 is referred to as a “second spherical portion 124”.

The distance between the first spherical surface portion 74 of the base 62 and the second spherical surface portion 120 is slightly larger than the distance between the first spherical surface portion 80 of the carriage 78 and the second spherical surface portion 124. Or they are set equal.

By setting the distance between each other in this way, the first spherical portion 74 and the first spherical receiver 80 are matched, and the second spherical portion 120 and the second spherical receiver 124 are matched. The base 62 is fixed on the carriage 78 so as to be tiltable without using members such as screws and screws (a fine adjustment mechanism is not shown). In this case, since a fixing member such as a screw is not required, the weight of the device can be reduced.

As shown in FIG. 10, lower left of the opening 72 of the yoke portion 112 which constitutes a magnetic circuit, i.e. Y ₂ direction Z in the middle direction between the _two directions, the magnetic body made of the guide rails 96a Is located. Y ₁ side of the guide rail 96b
In this embodiment, a shaft of a nonmagnetic material coated with an ethylene tetrafluoride resin or the like is used.

A mirror 126 is bonded to the carriage 78 instead of the prism 86 of the first and second embodiments.
The weight has been reduced. Other configurations are almost the same as those of the first and second embodiments.

Next, the operation of the embodiment constructed as described above will be described. As shown in FIG. 10, the yoke portion 112 of the U-shaped in the middle direction between the Y ₂ direction and the Z ₂ direction of the magnetic circuit formed by the first magnet 68, made of a magnetic material guide rails 96a Is located,
Leakage magnetic flux from the magnetic circuit reaches the guide rail 96a.

Here, more magnetic flux leaks from the opening 72 of the yoke portion 112, increasing the leak magnetic flux reaching the guide rail 96a. Although there is a portion where the base 62 exists between the first magnet 68 and the guide rail 96a, since the base 62 is made of a synthetic resin and is a non-magnetic material, it prevents the leakage magnetic flux reaching the guide rail 96a. It does not become. In this way, a suction force as shown by an arrow 128 acts on the guide rail 96a.

Since the guide rail 96a is fixed to a deck base (not shown), the carriage 78
A force in the opposite direction to 28 is generated and moves in this direction. As a result, regardless of the position of the carriage 78 in the X-axis direction,
The guide rail 96a and the driven bearing 92 are always in contact at the same position in the YZ plane.

The carriage 78 also moves as indicated by an arrow 130 in the main bearing 90 portion. Therefore, regardless of the position of the carriage 78 in the X-axis direction, the guide rail 96b and the main bearing 90 are always in contact at the same position in the YZ plane. Thereby, the carriage 7
The play between the eight and the two guide rails 96a, 96b can be eliminated. Other operations are almost the same as those of the first embodiment.

As described above, according to the present embodiment, since the objective lens is used as the holder end, it is easy to reduce the thickness of the lens mounting portion, and a mirror or the like can be approached. Can be. Further, since only one magnetic circuit is required for driving the holder 42, the weight can be reduced also in this respect. Further, as compared with the first and second embodiments, the number of guide rails attracted by the magnetic flux leaking from the magnetic circuit is reduced from two to one. Can be lightened,
One is enough.

The present invention is not limited to the above embodiments. For example, the positional relationship between the magnetic circuit and the guide rail can be variously modified. As described above, according to the present invention,
By applying the leakage flux of the magnetic circuit for driving the optical element mounted on the carriage to the guide rails of the magnetic body and biasing the slide bearings of the carriage to the guide rails, the magnetic flux is always unaffected by external vibrations and the like. It is possible to drive the movable section correctly and stably. Further, since no new components for applying the urging force are required, an inexpensive, small-sized and light-weight optical system driving device can be formed while utilizing a simple support structure of the slide bearing and the guide rail. Further, since the urging force is applied by the magnetic circuit mounted on the carriage and the guide rail, it is possible to always apply a stable urging force regardless of the position of the carriage in the radial direction of the medium.

[0067]

According to the present invention, there is provided an optical system driving device which stably urges a bearing against a guide rail without increasing the number of parts by utilizing a support system having a simple structure of a sliding bearing and a shaft. can do.

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view of the device shown in FIG. 1 in the YZ plane.

4 is a cross-sectional view showing a magnetic field distribution of the first magnet located on the Y ₁ side.

FIG. 5 is a perspective view showing a second embodiment of the optical system driving device according to the present invention.

6 is an exploded perspective view of a movable section of the device shown in FIG.

FIG. 7 is a sectional view of the device shown in FIG. 5 in the YZ plane.

FIG. 8 is a perspective view showing a third embodiment of the optical system driving device according to the present invention.

9 is an exploded perspective view of a movable portion of the device shown in FIG.

FIG. 10 is a sectional view of the device shown in FIG. 8 in the YZ plane.

FIG. 11 is a top view showing a first conventional example.

FIG. 12 is a front view showing a second conventional example.

FIG. 13 is a top view showing a third conventional example.

14 is a cross-sectional view of the device shown in FIG. 13 taken along line XX.

FIG. 15 is a perspective view showing a fourth conventional example.

[Explanation of symbols]

40: Objective lens, 62: Base, 64a, 64b: First inner yoke, 66a, 66b: First outer yoke, 68
a, 68b: first magnet, 72a, 72b: opening, 7
7: lens driving unit, 78: carriage, 90: main bearing,
92: driven bearing; 95: movable part; 96a, 96b: guide rail.

Claims (1)

(57) [Claims] An optical element, a carriage, a holder for holding the optical element, and the carriage being movable in a direction perpendicular to a recording surface of the disk-shaped recording medium and / or in a radial direction of the disk-shaped recording medium. A supporting means for supporting the above, a coil fixed to the holder and moving the holder in a direction perpendicular to the recording surface of the disk-shaped recording medium and / or in a radial direction of the recording medium, and attached to the carriage; A magnet for generating a working magnetic field;
A sliding bearing provided on the carriage; and a plurality of guide rails contacting the sliding bearing so as to support the carriage so as to be movable in a radial direction of the recording medium, wherein at least one of the guide rails is provided. The book is formed of a magnetic material so that the carriage is attracted by the action of the magnetic flux of the magnet.