JPH04149829A - Optical system driving device - Google Patents

Abstract

PURPOSE:To reduce the weight and size of an optical driving device and to improve the driving sensitivity of an objective lens and the resonance frequency of a holder by arranging the two sides of a carriage coil in a magnetic circuit, allowing a current to flow into the coil and applying a magnetic field to drive a carriage. CONSTITUTION:When current is allowed to flow into a focusing coil 3 or a tracking coil 4, a magnetic circuit is generated between magnets 8, a magnetic field is applied and the holder 2 is moved in a focusing direction and a tracking direction. A magnetic gap is formed between a magnet 16 and the carriage 7. Two sides of the carriage coil 14 in the Y direction are arranged in the gap, and when current is allowed to flow into the coil 14, the magnetic field generated in the magnetic circuit is applied. Thereby, the carriage 7 is driven in the tracking direction and a bearing 10 is pressed against rails 12, 13 without generating any play. Consequently, a mechanism such as a spring is made unnecessary, the weight and size of this optical system driving device can be reduced and the driving sensitivity of the objective lens 1 can be improved. In addition, the resonance frequency of the holder 2 of the lens 1 can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical system driving device, and in particular,
Recording information on information recording media such as optical cards and optical discs,
The present invention relates to an optical system drive device that drives an objective lens of an information recording and reproducing device that performs reproduction in a tracking direction and a focusing direction.

[Prior Art] When recording and reproducing information on an information recording medium such as an optical disk, an objective lens is provided at a position facing the recording surface of the recording medium, and this objective lens is driven in the force force direction and the tracking direction to adjust the position. is adjusted so that the light spot is properly irradiated onto the recording surface of the recording medium. in this case,
The carriage on which the objective lens is mounted is driven (driving), the position of the objective lens is coarsely adjusted, and track access is performed.
Next, the objective lens is moved in the tracking direction and the focusing direction to finely adjust its position. Therefore, the objective lens driving device requires a fine actuator that drives the objective lens in the focusing direction and the tracking direction, and a carriage actuator (coarse actuator) that drives the carriage.

A precision actuator is usually composed of a coil, a magnet, a yoke, etc. Conventionally, these members are placed on a carriage together with an objective lens, and the carriage is driven in the tracking direction to perform track access. Therefore, the movable mass of the carriage actuator becomes large because it includes the mass of the members constituting the precision actuator and the objective lens in addition to the mass of the carriage itself. For this reason, there is a drawback that the track access speed becomes slow. Furthermore, the number of parts in the entire drive device is large, making it difficult to downsize the entire device.

As a device to solve such problems, for example,
There is an optical system driving device disclosed in Japanese Patent No. 9-135638. In this optical system drive device, a part of the magnetic circuit that makes up the fine actuator for finely adjusting the position of the objective lens is shared with a part of the magnetic circuit that makes up the coarse actuator that drives the carriage. ,
Efforts have been made to make the entire drive device lighter and smaller. 14th
The figure is a plan view of an optical system driving device disclosed in Japanese Patent Application Laid-Open No. 59-135638, and FIG. 15 is a cross-sectional view of the device shown in FIG. 14 taken along line A-A. As is clear from these figures, either the stator magnet 71, 72 or the objective lens 7
The stator magnets 71 and 7 extend parallel to the outside of the support rods 73 and 74 supporting the stator magnets 71 and 7.
A magnetic gap 80.81 is formed between the two. Carriage coil 75, 76 and actuator coil 77
．． 78 is supported by support rods 73 and 74.

In this way, the magnetic circuit for driving the objective lens 79 and the magnetic circuit for driving the holding member of the objective lens share the stator magnets 71 and 72, thereby reducing the weight and size of the entire device. We are trying to

[Problems to be Solved by the Invention] However, in the above-described device, since the two magnetic circuits share the stator magnets 71 and 72, although the weight of the device can be reduced, The distance between the magnetic gaps becomes wider, and the actuator coils 76 and 77 have to be located away from the objective lens 79. Therefore, the holder for the objective lens 79 also becomes large, and the weight of the movable part increases, which reduces the driving sensitivity of the objective lens in the focusing direction. Furthermore, the resonance frequency of the holder of the objective lens 79 becomes low, causing problems in drive control.

The present invention has been proposed to solve these problems, and aims to reduce the weight and size of an optical system drive device, improve the drive sensitivity of the objective lens, and improve the resonance frequency of the objective lens holder. With the goal.

Means and Effects for Solving the Problems] In order to solve the above problems, the optical system driving device of the present invention includes an optical element that focuses a light spot on an information recording medium, and a focusing direction and a focusing direction of the optical element. Alternatively, a first coil driven in the tracking direction, a first magnetic circuit that cooperates with the first coil, the optical element and the first coil are mounted, and the structure is movable in the tracking direction. a second coil that drives the carriage in the tracking direction; and a second coil that cooperates with the second coil.
a magnetic circuit, and support means for movably supporting the carriage in the tracking direction, wherein at least a part of the first magnetic circuit and at least a part of the second magnetic circuit are common to the carriage. It is characterized by being configured.

As described above, in the optical system driving device of the present invention, at least a part of the magnetic circuit cooperates with the first coil that drives the objective lens in the focusing direction and/or the tracking direction, and the first coil that drives the carriage in the tracking direction. Since at least a part of the magnetic circuit No. 2 is configured to be common to the carriage on which the objective lens is placed, it is possible to reduce the size and weight of the members placed on the carriage.

Further, in the optical system driving device of the present invention, the carriage is pressed against the support means by using the magnetic attraction force of a magnet forming the first magnetic circuit and/or a magnet forming the second magnetic circuit. It is characterized by the fact that

As described above, in the optical system drive device of the present invention, the carriage is brought into contact with the carriage support means by utilizing the magnetic attraction force of the magnets forming the first and/or second magnetic circuits. , a member for preventing rattling of the carriage is not required, and the entire apparatus can be made smaller and lighter, and the manufacturing cost can be reduced.

Further, in the optical system driving device of the present invention, the carriage is magnetically separated, and a magnetic gap that cooperates with the first coil is formed in at least a part of the separated portion of the carriage. This is a characteristic feature.

As described above, in the optical system driving device of the present invention, the carriage is magnetically separated, and the separated portion of the carriage forms a magnetic gap that cooperates with the first coil. Magnets for the focusing actuator and tracking actuator are not required, and the mass of the movable part can be reduced. Therefore, it is possible to improve carriage drive sensitivity.

[Embodiment] FIGS. 1 to 4 are diagrams showing a first embodiment of the optical system driving device of the present invention. FIG. 1 is an assembled perspective view of the optical system drive device of the present invention, FIG. 2 is an exploded perspective view, and FIG. 3 is a side view in the Y direction of the optical system drive device shown in FIG.
4 is a partial side view of the optical system driving device shown in FIG. 1 in the X direction. In the attached drawings, the X direction indicates the tracking direction, the Y direction indicates the tangential direction, and the Z direction indicates the focusing direction.

As shown in FIGS. 1 and 2, an objective lens 1 is mounted on an objective lens holder 2, and a focus coil 3 is wound around the outer circumference of the holder 2. As shown in FIGS. Furthermore, two tracking coils 4 wound in a square shape are attached to each side of the holder 2 in the X direction. A total of four protrusions 2a, two on the upper and lower sides, are provided approximately at the center of the side surface of the holder 2 in the Y direction, and the holding member 5 and these protrusions 2
A tube-shaped damper 6 is stretched between the The damper 6 is a tube made of rubber or the like attached around a metal wire made of beryllium copper or the like and having a diameter of about 0.1, and the damper 6 restricts the movement of the holder 2 in the tracking direction. A claw 5a is formed on the lower side of the holding member 5, and as shown in FIG. 3, this claw 5a is located near the rail 12 when the drive device is assembled, and is protected from excessive external shock. This serves as a stopper to prevent the bearing from coming off the rail when the rail is loaded.

As mentioned above, the movement of the holder 2 in the Y direction is restricted by the damper 6, but the optical system drive device of the present invention is mainly intended for small recording media such as 3.5-inch floppy disks. The objective lens holder only needs to move about ±8 in the tracking direction.
If the movement is restricted by a damper within this range, there will be no problem.

The above-mentioned members such as the objective lens 1, objective lens holder 2, focusing coil 3, and tracking coil 4 are placed on the carriage 7.

The carriage 7 is formed by press forming an iron plate with a thickness of about 1.2 mm, and has an outer yaw 7a as shown in FIG.
, 7a and the inner yokes 7b, 7b are raised in the X direction. Further, there are convex portions 7c and 7d on three sides of the carriage 7.

7e, and holes for fixing the bearings are bored in each convex portion. Magnets 8, 8 are fixed inside the outer yokes 7a, 7a, and the magnets 8, 8 and the inner yokes 7b
, 7b to form a magnetic cap.

A mirror 9 is arranged between the inner yokes 7b and 7b.

This mirror 9 is located directly below the objective lens 1 as shown in FIG.
It also acts to guide reflected light from a recording medium (not shown) to a photodetector. As is clear from FIG. 1, when the holder 2 is mounted on the carriage 7, the inner yokes 7b, 7b are connected to the holes 2 formed inside the holder 2.
b, 2b, and the outer yoke 7a is inserted between the holder 2 and the holding member 5.

A drum-shaped bear link 10.10 is press-fitted into the hole drilled in the convex portions 7c and 7d of the carriage 7, and a conical bearing 11 is press-fitted into the hole drilled in the convex portion 7e.
The carriage 7 is mounted through these bearings 10.1O111.

A carriage coil 14 wound in a square shape is fixed to the bottom surface of the carriage 7, and magnets 16, 17 and a yoke 15 are installed below the carriage coil 14. The surface of magnet 16 is N pole, 17
The surface of is magnetized to the south pole. magnet 16.17
are arranged and fixed on the yoke 15 in the X direction.
The two rails 12 and 13 are fixed to a fixed part (not shown) and support the carriage 7 so as to be movable in the tracking direction. An FPC 18 is attached to the fixed member 5, and power is supplied to the focus coil 3, tracking coil 4, and carriage coil 7 via this FPC. F
The other end of the PC 18 is fixed to a fixed part (not shown).

When a current is passed through the focus coil 3 or the tracking coil 4, a magnetic field generated at the opening of the magnet 8.8 acts, and the holder 2 is driven in the focus direction and the tracking direction. As shown in Figure 4, magnets 16 and 1
A magnetic gap is formed between the motor 7 and the carriage 7, and a magnetic circuit is formed in the order of magnet 16→carriage 7→magnet 17→yoke 15→magnet 16. Two sides of the carriage coil 14 in the Y direction are located within this magnetic gap, and when current is applied to the carriage coil 14, the magnetic field generated between the magnets 16 and 17 acts, causing the carriage 7 to be tracked. drive in the direction.

Since the carriage 7 is magnetically attracted to the magnet 16.17, the bearing 10.10.11 is pressed against the rail 12.13 without play. Therefore, a mechanism such as a spring that applies preload to the carriage against the rail is not required, and the structure of the apparatus is simplified.

As described above, in the optical system drive device of the present invention, since the carriage itself constitutes a part of the magnetic circuit that drives the carriage in the tracking direction, the number of parts can be reduced. Further, since the carriage is formed by press molding, the holes for mounting the bearing can be formed at the same time, and manufacturing costs can be reduced. Further, since the coil and magnet for driving the carriage are arranged on the bottom surface of the carriage, the size of the device in the tangential direction can be reduced.

In the embodiments described above, a moving coil is used in which the carriage coil is fixed to the carriage, but the magnet may be fixed to the carriage.

5 to 7 are diagrams showing a second embodiment of the optical system driving device of the present invention. FIG. 5 is an exploded perspective view, FIG. 6 is a plan view, and FIG. 7 is a partial side view. In these diagrams,
Only the parts that are different from the first embodiment are shown, and the common parts are omitted.

In this embodiment, the carriage 20 is separated into an inner yoke portion 20-1 and an outer yoke portion 20-2. As shown in FIG. 5, the inner yoke portion 20-1 has an iron plate raised at approximately the center to form inner yokes 20a, 20a, and three protrusions 20c, 20d, 20e are provided, each of which has a raised iron plate. A hole is drilled in the hole for fixing the bearing. Outer yoke part 20
-2, the outer yokes 20b, 20b are raised at a wider interval than the inner yokes 20a, 20a, and the inner yoke portion 20
-1 and the outer yoke portion 20-2 constitute a carriage 20. Inner yokes 20a, 20a and outer yokes 20b, 2
Carriage coil 1
4 is fixed, and magnets 16, 17 and yokes 15 are arranged below the carriage coil 14 to form a magnetic gap 22 between the inner yokes 20a, 20a and the outer yokes 20b, 20b.

With this configuration, a magnetic circuit consisting of magnet 16→carriage 20→magnetic gap 22→yoke 21→magnet 17→yoke 15 is formed. In this embodiment, the focus coil 3 is placed within the magnetic gap 22.
and tracking coil 4 are located, and the magnetic field generated in the magnetic gap 22 acts on these coils, driving the objective lens 1 in the focusing direction and the tracking direction. Therefore, in this embodiment, magnets for the focusing actuator and the tracking actuator are not required, the number of parts of the apparatus is further reduced, and the weight of the movable parts can be reduced.

8 to 10 are diagrams showing a third embodiment of the optical system driving device of the present invention. FIG. 8 is an exploded perspective view, FIG. 9 is a plan view, and FIG. 1O is a side view.

As shown in FIG. 8, focus coils 31 and 31 wound in a prismatic manner are fixed to both sides in the X direction of the objective lens holder 30 with the objective lens l mounted on the upper surface, and the focus coils 31 and 31 are fixed to the outside of the focus coil 3131. A tracking coil 32.32 which is wound in a letter shape and bent at the center is fixed. Two thin focusing plate springs 3 are attached to one end of the objective lens holder 30 in the X direction.
One end of 3.33 is mounted so that the leaf springs are parallel to each other. The other end of the leaf spring 33.33 is further fixed to the relay member 34. Further, one ends of two tracking leaf springs 35.35 are fixed to the negative end of the relay member 34 in the X direction so that the leaf springs 35.35 are parallel to each other. 35. The other end of 35 is fixed to the holding member 36. A pin 36a is formed at the lower end of the holding member 36, and this pin 36a fits into a hole 37 provided in the carriage 37.
f to fix and position these members.

The carriage 37 is formed by press-molding an iron plate, and has a fixed part 37a.
, 37a and the yoke portions 37b, 37b. 8th
As is clear from the figure, the fixing parts 37a, 37a are formed outside the yoke parts 37b, 37b. The fixed parts 37a, 37a are provided with two-pole magnetized magnets 38.
Approximately half of one magnetic pole face of 38 is fixed.

The other half of magnet 38.3B is inner yoke 37b,
37b and a magnetic gap 43 between them.
．． 43 is formed. A carriage coil 40.4 is located at a position facing the other magnetic pole surface of the magnet 38.38.
0 and yoke 41.41 are installed.

The carriage 37 has three protrusions 37c, 37ci,
37e are provided, each having a hole for fixing the bearing, and the outer ring is a spherical bearing 39.39.
39 is press-fitted and fixed. V grooves 41a, 41a are formed in the center of the yoke 41, 41 in the X direction,
Outer rings of 39.39.39 are in contact with the respective bearings in these V-grooves 41a, 41a. As is clear from FIG. 9, the outer side of one yoke 41 has a spring 45.4.
5, and due to the elasticity of this spring, the yoke 4
1 is pressed against the bearing 39. The objective lens holder 30 and the relay member 34 are provided with holes 30a and 34a, and light from a fixed optical system (not shown) in which a light emitting element, a light receiving element, etc. are fixed passes through these holes and reaches the objective. It is reflected by the mirror 9 provided below the lens holder 30,
It enters the objective lens l and connects the spot on the information recording medium surface. The hole 37g provided in the center of the carriage 37 is for reducing the weight of the carriage.

A magnetic circuit is formed in the order of magnet 38 -> yoke 41 -> magnet 38 -> inner yoke 37b -> carriage 37 -> fixed part 37a, and when current is passed through focus coil 31,
This current acts on the magnetic field of the magnetic gap 43 formed between the inner yoke 37b and the magnet 38, and a force is generated in the focusing direction.
3. Drive the objective lens 1 in the focusing direction by tilting 3.33. Similarly, when a current is applied to the tracking coil 32, a force in the tracking direction is generated, and the tracking plate springs 35 and 35 are bent to drive the objective lens 1 in the tracking direction. In addition, the carriage coil 40
When a current is applied to , 2 parallel to the Z direction of the carriage coil
Since the directions of the magnetic fields acting on the sides are opposite to each other, force is generated in the tracking direction, causing the bearing 39 to move toward the yoke 41.
The carriage 37 moves along the V groove 41a formed in the
is driven in the tracking direction.

In this embodiment, the carriage coils 40 and 40 are arranged on the fixed side, and the magnets 38 and 38 are fixed to a part of the carriage 37. Therefore, unlike the first and second embodiments, the magnets 38, 38 move relative to the yoke 41 in the tracking direction. In this embodiment, since the magnets 38 and 38 are used for each of the focusing actuator, tracking actuator, and carriage actuator, the number of parts can be reduced and the size can be reduced. Further, the carriage coil 40 and the yoke 41 are
Since it is provided on the side surface of the carriage 37, the dimension in the height direction can be reduced.

FIG. 1I is a perspective view showing a modification of the yoke 41 used in the third embodiment described above. In this example, the yoke 46 is integrally formed in a U-shape, and the elastic force of the yoke 46 applies preload to the bearing 39, and the V-groove 46a provided in the bearing 39 and the yoke 46.

This is to prevent wobbling of 46a. In addition, since the yoke 46 is made integrally, the two V grooves 46
a, 46a can be made with high precision.

FIGS. 12 and 13 are a plan view and a sectional view showing a fourth embodiment of the optical system driving device of the present invention. Hereinafter, only the parts that are different from the third embodiment will be explained, and the explanation of the similar parts will be omitted.

In this example, without providing a tracking coil,
The position of the objective lens 1 in the tracking direction is corrected by moving the carriage in the tracking direction. Carriage 5 used in this example
5 is different from the above-mentioned embodiments in that it does not have a convex portion, and as shown in FIG.
5a, and then raise the inner yokes 55b, 55b inside the fixing parts 55a, 55a. One half of the unipolar magnetized magnet 1-56, 56 is fixed to the outside of the fixed part 55a, and the other half faces the inner yokes 55a, 55a. A focusing coil 52 is wound around the inner yokes 55a, 55a. The outermost yoke 57 is formed in a U-shape, and carriage coils 58 and 58 are wound around both arms of the yoke 57. The reference numeral 53 designates a focusing plate spring, which has one end fixed to the objective lens holder 51 and the other end fixed to the holding member 54 as in the third embodiment.

As shown in FIG. 13, a guide 59 is installed so as to face the bottom surface of the carriage 55, and two V-grooves 55a, 55a, 59a are provided in the bottom surface of the carriage 55 and the top surface of the guide 59 in the tracking direction, respectively. 59a is provided. A plurality of balls 60 are arranged between each V-groove, and a retainer 61 is provided between the carriage 55 and the guide 59 in order to regulate the position of the balls 60.

The carriage 55 is moved into the V-groove 55 by the rotation of the ball 60.
a.

59a in the tracking direction.

As is clear from FIG. 13, the magnets 56.56 are offset upwards with respect to the yokes 57.57. Therefore, due to the magnetic attractive force acting between the magnet 56.56 and the yoke 57.57, the carriage 55 and the ball 60
will be pressed by the guide 59.

[Effects of the Invention] As described above, in the optical system drive device of the present invention, since part of the magnetic circuit and the carriage are shared, the component configuration is simplified and the device can be easily assembled. Furthermore, since the mass of the movable part can be reduced, it is possible to provide an optical system drive device that can be accessed accurately, and the entire device can be downsized. Furthermore, by using the magnetic attraction of the magnets that make up the magnetic circuit,
Since the carriage is brought into pressure contact with the support member of the carriage via the bearing, there is no need for special parts to prevent rattling between the bearing and the support member, making assembly easy and compact. easy to change. The magnetic gap for driving the objective lens is obtained by using a separate carriage, and by using a fixedly placed magnet for driving the objective lens, the mass of the movable part can be reduced. is possible,
The carriage drive sensitivity can be increased. Furthermore, since the coil for driving the objective lens can be placed near the objective lens, it is possible to improve the driving sensitivity of the objective lens. Furthermore, the resonant frequency of the objective lens can be increased, making control easier.

[Brief explanation of drawings]

1 to 4 are diagrams showing a first embodiment of the present invention, FIGS. 5 to 7 are diagrams showing a second embodiment of the present invention, and FIGS. 8 to 10 are diagrams showing a first embodiment of the present invention. FIG. 11 is a diagram showing a modification of the third embodiment of the invention. FIGS. 12 and 13 are diagrams showing a fourth embodiment of the invention. 14 and 15 are diagrams showing a conventional optical system driving device. 1...Objective lens 2.30.5o...Holder 3.31.52...Focus lens coil 4.32
...Tracking coil 5...Holding member 7.20.37.55...Carriage 7a...Outer yoke 7b, 20a, 55b...-Inner yoke 8...Magnet 9...Mirror 10. 11.39...Bearing 12.13...Guide rail 14.40.58...Carriage coil 16.17.
38.56...Magnet 15.41.57...Yoke 20b, 55a...Fixing part 20c, 20d, 20e, 37c, 37d,
37e...Protrusion 41a...V groove 46...Yoke 46a...V groove 599...
Guide 60...Ball 61...Retainer Fig. 1 'Link' to Fig. 10 Fig. 2 Fig. 4 Fig. 5 Fig. 4 Horse Fig. 7 Fig. 9 Fig. 1O Fig. 11 Fig. 14 Procedure amendment document 1991 January 14th

Claims (1)

[Claims] 1. An optical element that focuses a light spot on an information recording medium, a first coil that drives this optical element in a focusing direction and/or a tracking direction, and a first coil that cooperates with this first coil. a carriage on which the optical element and the first coil are mounted and configured to be movable in the tracking direction; a second coil for driving the carriage in the tracking direction; a second magnetic circuit that cooperates with a second coil; and support means for movably supporting the carriage in the tracking direction;
An optical system driving device characterized in that at least a portion of the first magnetic circuit and at least a portion of the second magnetic circuit are configured in common with the carriage. 2. A claim characterized in that the carriage is brought into pressure contact with the support means by utilizing the magnetic attraction force of a magnet forming the first magnetic circuit and/or a magnet forming the second magnetic circuit. Item 1. The optical system drive device according to item 1. 3. The optical system according to claim 1, wherein the carriage is magnetically separated, and a magnetic gap that cooperates with the first coil is formed in at least a part of the separated portion. Drive device.