JPH10154383A - Optical system driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure reducing external vibration giving the adverse effect to a carriage by grease and to prevent the obstruction of the movement of the carriage by the viscosity of grease. SOLUTION: The movement of a carriage is supported by guide shafts 21a, 21b and bearings 14, 15. Guide members 22a, 22b in parallel with the guide shafts 21a, 21b are arranged on a deck base and bearing bodies 16a, 16b into which the guide members 22a, 22b are inserted lefting a gap are formed on the carriage. By filling grease in a clearance between the guide members 22a, 22b and the bearing bodies 16a, 16b, external vibration is reduced. Since grease is not filled in the guide shafts 21a, 21b and the bearings 14, 15, the movement of the carriage is not obstructed by the viscosity of grease.

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 for moving an optical head with respect to a recording medium provided in an optical recording / reproducing apparatus for optically recording / reproducing information.

[0002]

2. Description of the Related Art In an optical recording / reproducing apparatus for a disk-shaped recording medium such as an optical disk, information is reproduced and recorded while an optical head provided with an optical element such as an objective lens moves in a radial direction. As a conventional driving device for moving the optical element, one having a structure described in JP-A-63-184967 is known.

In this conventional apparatus, an oil-impregnated round bearing and an oil-impregnated long-hole bearing are formed on a carriage on which an optical element is mounted, a guide shaft is passed through each of these bearings, and the carriage is moved along the guide shaft by a linear motor. And move it.

[0004]

The above-described carriage moves smoothly in the radial direction of the recording medium, and
When vibration is applied, it is necessary to avoid extra movement due to the vibration. However, the structure in which the carriage slides along the guide shaft is less expensive than a structure using a bearing, but requires a gap between the guide shaft and the bearing to allow sliding. Therefore, when strong vibration is applied from the outside, the carriage moves
Rattle. In particular, in the case of a so-called separation optical system in which a movable optical system is divided into a moving optical system on a carriage and a fixed optical system on a fixed side in order to reduce the weight of the movable unit, the servo signal is adversely affected by rattling.

In the device disclosed in Japanese Patent Application Laid-Open No. 63-184967, an oil-impregnated bearing is used as a bearing on which the guide shaft slides, and an oil film is formed between the guide shaft and the bearing, so that the sliding is performed smoothly. be able to. However, since the oil has low viscosity, vibration is not absorbed by the oil, and rattling occurs due to external vibration. On the other hand, filling viscous grease instead of oil between the guide shaft and the bearing reduces the viscosity of the grease by absorbing the shock of vibration. Since the carriage is high, it becomes a resistance when the carriage moves. In particular, in the case of a one-stage servo system in which tracking is performed by directly driving the carriage, it becomes impossible to follow the runout of the track or cause a seek failure due to a large resistance.

As means for eliminating the influence of vibration,
It is conceivable to apply a preload so that the bearing is pressed against the guide shaft.However, similarly, the friction when the carriage moves increases, making it difficult to follow the track, failure in seeking, and deterioration of the life of the shaft. Problems arise.

The present invention has been made in view of such circumstances, and in a structure in which a carriage slides on a guide shaft, smooth movement of the carriage and prevention of rattling due to vibration are provided. It is an object of the present invention to provide an optical system driving device that is enabled.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a carriage to which an optical element is attached, and which penetrates the carriage substantially in the radial direction of the recording medium to guide the movement of the carriage. A parallel guide shaft, a bearing provided in a portion of the carriage that penetrates the guide shaft and supporting sliding with the guide shaft, and a shaft-shaped guide member extending in a direction parallel to the guide shaft and penetrating the carriage. A bearing member provided on a carriage such that the guide member penetrates with a gap larger than a gap between the guide shaft and a bearing that supports sliding of the guide shaft; And a viscous lubricant filled in a gap between them.

In this structure, the carriage moves smoothly by sliding between the guide shaft and the bearing. The viscous lubricant reduces external vibrations due to the viscosity. This lubricant is filled between the bearing and the shaft-shaped guide member provided separately from the bearing and the guide shaft, but these shaft-shaped guide members and the bearing body are members that support the movement of the carriage. Instead, it has a larger gap than the guide shaft supporting the movement and the bearing. Therefore, by filling a viscous lubricant between them, there is no need to fill a viscous lubricant between the guide shaft and the bearing for supporting the movement, and the movement of the carriage is caused by the viscosity of the lubricant. Is not hindered.

According to a second aspect of the present invention, there is provided a carriage on which an optical element is mounted, a parallel guide shaft which penetrates the carriage along a substantially radial direction of the recording medium and guides the movement of the carriage, and a guide shaft of the carriage. A bearing provided at the penetrating portion for supporting sliding of the guide shaft, a plate-like guide member extending in a direction parallel to the guide shaft, and provided on the carriage such that the guide member penetrates with a gap. And a viscous lubricant filled in a gap between the slit and the guide member.

Also in this structure, the guide shaft and the bearing support the movement of the carriage, and the lubricant filled between the plate-shaped guide member, which is not the support member, and the slit reduces the vibration by viscous fluid. I do. Therefore, not only the movement of the carriage due to sliding becomes smooth, but also the adverse effect of vibration is eliminated.

According to a third aspect of the present invention, there is provided a carriage on which an optical element is mounted, a parallel guide shaft which penetrates the carriage along a substantially radial direction of the recording medium, and guides the movement of the carriage, and a guide shaft of the carriage. A magnetic circuit member that is provided in the penetrating portion and supports the sliding of the guide shaft, includes a coil to which current is supplied, a magnet and a yoke that applies a magnetic field to the coil, and generates a driving force of the carriage; It is characterized in that a viscous lubricant filled in a gap between the coil and the yoke of the magnetic circuit member is provided.

In this structure, a lubricant is filled between a coil and a yoke of a magnetic circuit member for generating a driving force on the carriage, and a guide shaft and a bearing for supporting sliding of the carriage are filled with the lubricant. Never. For this reason, the carriage can be smoothly moved by sliding, and is not adversely affected by vibration.

[0014]

1 to 3 show a first embodiment of the present invention. As shown in FIG. 2, a focus actuator 8, a carriage 11 and a cover 20 are provided.

A focus actuator 8 supports the objective lens 1 and has a holder 2 on which focus coils 3a and 3b are mounted, and a pair of upper and lower leaf springs 4a and 4
b, and a spring receiving member 5 having a convex boss 6 formed on the back surface. The leaf springs 4a and 4b have one end joined to the holder 2 and the other end joined to the spring receiving member 5. Thus, the holder 2 and the spring receiving member 5 are connected. The focus actuator 8 includes a leaf spring 4
The holder 2 supports the holder 2 so as to move in the direction (Z direction) of the recording medium (not shown) by a and 4b.
Reference numeral 7 denotes a mounting leaf spring mounted on the holder 2 side of the spring receiving member 5.

As shown in FIG. 2, the upper surface of the carriage 11 has a fitting groove 12 into which the convex boss 6 of the focus actuator 8 fits and mounting protrusions 13a and 13b into which the mounting leaf spring 7 is fitted. A central portion 30 having
End portions 40, 40 extending laterally from both sides of the central portion 30. Reference numeral 17 denotes a reflection mirror adhered to the central portion 30 so as to be located close to the objective lens 1. Further, the central portion 30 is formed with a main bearing 14 and a driven bearing 15 through which guide shafts 21b and 21a (see FIG. 3) mounted in parallel with a deck base (not shown) respectively penetrate.

The tracking coils 18a and 18b are fixed to the left and right ends 40 by bonding, respectively, and bearings 16a and 16b are formed outside the mounting portions of the tracking coils 18a and 18b. The tracking coils 18a and 18b and the focus coils 3a and 3b are connected to a control circuit via a flexible wiring board (not shown), and a current is supplied from the flexible wiring board.

The cover 20 covers the focus actuator 8, and includes an outer first cover portion 20a,
It consists of two members, a second cover part 20b fixed inside. In this way, the cover 20 can perform the function of a mass balancer by using the cover 20 as two members and increasing the mass of the portion away from the center.

As shown in FIG. 3, the main bearing 14 of the carriage 11 has a shape obtained by cutting a circle having a larger diameter than the guide shaft 21b passing through the bearing 14 on four planes. When the guide shaft 21b is a shaft having a fitting tolerance h6, for example, the fitting tolerance G6
Is set so as to correspond to the hole diameter.

As shown in FIG. 3, the driven bearing 15 of the carriage 11 has a shape obtained by cutting a circle having a larger diameter than the guide shaft 21a penetrating the bearing 15 into two planes. When the guide shaft 21a is a shaft having a fitting tolerance h6, for example, the fitting tolerance G
6 is set to correspond to the hole diameter.

The main bearing 14 and the driven bearing 15 are formed integrally with the carriage 11, so that the entire carriage 11 is made of a synthetic resin mixed with carbon fibers having good slidability. In addition, these bearings 1
The surfaces of the guide shafts 21b, 21a penetrating through 4, 4 are coated with a resin having good slidability such as tetrafluoroethylene resin. Therefore, since the bearings 14 and 15 and the guide shafts 21b and 21a relatively slide with a small frictional resistance, the carriage 11 can be smoothly moved along the guide shafts 21b and 21a.

Each of the bearing bodies 16a and 16b of the carriage 11 is formed to have a circular cross section, and axial guide members 22a and 22b formed on the deck base penetrate therethrough. The diameters of these bearing bodies 16a, 16b are larger than the diameters of the guide members 22a, 22b, and the gaps between the bearing body 16a and the guide member 22a and the gaps between the bearing body 16b and the guide member 22b are smaller than the bearings. It is larger than the gap between the guide shafts 14 and 15 and the guide shafts 21a and 21b. For example, bearings 14 and 15 and guide shafts 21a and 21b
Is between several μm and several tens of μm, whereas the gap between the bearing bodies 16a, 16b and the guide members 22a, 22b is set on the order of several hundred μm. For this reason, while the bearings 14 and 15 and the guide shafts 21a and 21b are supported in contact with each other, the bearing bodies 16a and 16b and the guide members 22a and 22b are in a non-contact state. In addition,
The shaft-shaped guide members 22a, 22b are
It is attached to the deck base so as to be parallel to 1b.

The gap between the bearings 16a, 16b and the guide members 22a, 22b is filled with a viscous lubricant 19. Grease or other viscous oil is used as the lubricant 19.
After filling in the gaps between the a and 16b and the guide members 22a and 22b, they are accumulated in the gaps due to their viscosity and do not flow out.

In FIGS. 1 and 3, reference numerals 23a and 23b denote inner yokes that pass through the insides of the tracking coils 18a and 18b. A short ring 2 made of copper having a thickness of about 0.2 mm is provided on the outer peripheral portions of the inner yokes 23a and 23b.
4a and 24b are wound and fixed by swaging. Outer yokes 25a and 25b are provided above the inner yokes 23a and 23b in the Z direction.
Magnets 26a and 26b are adhered to the lower surface of 25b.

The guide shafts 21a and 21b, the guide members 22a and 22b, and the inner yokes 23a and 23b are fixed to the deck base, and the outer yokes 25a and 25b pass through the inner yokes 23a and 23b as shown in FIG. Is fixed to the deck base.

Next, the operation of the present embodiment configured as described above will be described. Laser light emitted from a fixed optical system (not shown) is reflected by a reflection mirror 17 on the carriage 11 and then reflected by the objective lens 1.
A spot is formed on a recording medium (not shown). The reflected light from the recording medium returns to the fixed optical system through the objective lens 1 again, and a focus error, a tracking error, and a recording signal are detected.

When a focus error is detected, the current is supplied to the focus coils 3a and 3b to drive the holder 2 in a direction perpendicular to the medium surface. If a tracking error is detected, the tracking coil 1
By supplying current to 8a and 18b, the holder 2 is driven together with the carriage 11 in the radial direction of the recording medium. Even when accessing different tracks, the holder 2 is driven together with the carriage 11 in the radial direction of the medium by supplying current to the tracking coils 18a and 18b. As described above, the focus control, the tracking control, and the access control of the holder 2 and the objective lens 1 fixed thereto are performed.

When external vibration is applied to the apparatus, the vibration is reduced by the grease 19 filled between the bearing members 16a and 16b and the guide members 22a and 22b. Less. At this time, the bearing bodies 16a, 16b and the guide members 22a, 22
Since there is no direct contact with b, the movement of the carriage 11 is not reduced by the grease 19. In addition, since the gap is large, dust adhering to the grease is removed by the bearings 16a, 16a.
It does not happen that the carriage gets stuck in the position b.

It is preferable that grease as a viscous lubricant has a small volatile component and does not affect synthetic resin parts such as the carriage 11. For this purpose, those using an olefinic synthetic oil as a base oil are preferable. Fluorine-based grease is also suitable. However, when the use of the carriage is not required for a long period of time or when the carriage is made of a stable material, the base oil may be another synthetic oil, mineral oil, or petroleum. The thickener in the component may be a soap type such as lithium or sodium, a urea type such as aromatic diurea, or other organic or inorganic type. Also, a material to which a solid lubricant such as tetrafluoroethylene resin or molybdenum disulfide is added is effective if the particle size is appropriate. Even if the lubricant is oil instead of grease,
The effect of suppressing the rattling of the carriage is the same, but grease is superior in terms of controlling the amount of application and having less run-out after application.

In this embodiment, guide members 22a, 22b are provided on bearings 16a, 16b filled with grease, respectively.
2b, the guide member may be one. Also,
The cross section is not circular but may be, for example, a rectangular cross section. In the present embodiment, the guide shafts 21a and 21b for supporting the carriage and the bearings 14 and 15 are dry-lubricated with polytetrafluoroethylene resin, but may be oil-lubricated. When lubricating with grease, apply low-viscosity grease to parts that were dry-lubricated so as not to hinder carriage movement and high-viscosity grease to parts that were filled with grease to reduce vibration. Fill. Further, a magnetic fluid may be used instead of the lubricant.

FIGS. 4 and 5 are a perspective view and a sectional view of a second embodiment of the present invention. In this embodiment, slits 31a,
31b are formed. The slits 31a, 31b are formed along the horizontal direction (y direction) from the outer surfaces of the holding block portions 40, 40, and the outer ends are free ends. 32a and 32b are these slits 31a and 31
It is a guide member penetrating through the inside b, and is formed in a plate shape. The guide members 32a, 32b are
It is attached to the deck base so as to be parallel to 21b. A gap is formed between the slits 31a, 31b and the guide members 32a, 32b, and the gap is filled with a viscous lubricant 33 such as grease.
External vibration acting on the carriage 11 is reduced. Other configurations are the same as those of the first embodiment.

In the second embodiment, a plate-like guide member 3 is provided at a portion filled with a lubricant for reducing external vibration.
Since 2a and 32b are used, manufacture is easy and assembly is easy.

FIGS. 6 and 7 show a perspective view and a sectional view of the third embodiment. The carriage 11 is formed by removing the holding block portions 40 on both sides of the mounting block portion 30. FIG. I have. That is, the carriage 11 is not provided with the guide member and the bearing member or the slit through which the guide member is inserted. In this embodiment, the gap between the left and right tracking coils 18a, 18b and the inner yokes 23a, 23b is filled with a viscous lubricant 36 such as grease.

Therefore, in this embodiment, the inner yoke 23
The lubricant 36 between the a and 23b and the tracking coils 18a and 18b alleviates the external vibration and reduces the adverse effect. For this reason, in this embodiment, it is not necessary to newly increase the number of components in order to fill the lubricant 36, so that an inexpensive device having a simple structure can be provided. Further, in the present embodiment, the tracking coils 18a and 18b are air-core coils, but may be bobbin-wound coils, which has an advantage that the size of these gaps can be easily managed.

The present invention described above also includes the following inventions. (1) A carriage to which an optical element is attached, a guide shaft that penetrates through the carriage substantially in the radial direction of the recording medium, and guides the movement of the carriage, and an oil-based lubricant provided at a portion of the carriage where the guide shaft passes. A bearing that supports sliding of the guide shaft through the shaft, a shaft-shaped guide member that extends in a direction parallel to the guide shaft and penetrates the carriage, and the guide member supports the sliding of the guide shaft and the guide shaft. A bearing body provided on the carriage so as to penetrate with a gap larger than the gap between the bearing body and the oil-based lubricant, and filled in the gap between the bearing body and the guide member. An optical system driving device comprising: a lubricant.

(2) A carriage to which an optical element is attached, a guide shaft which penetrates the carriage along a substantially radial direction of the recording medium, and guides the movement of the carriage, and an oily material provided at a portion of the carriage where the guide shaft penetrates. A bearing that supports sliding with a guide shaft via a lubricant, a plate-shaped guide member that extends in a direction parallel to the guide shaft and penetrates a carriage, and that the guide member penetrates with a gap. An optical system driving device comprising: a slit provided in the carriage; and a lubricant having a higher viscosity than the oil-based lubricant and filled in a gap between the slit and the guide member.

(3) A carriage on which an optical element is mounted, a guide shaft that penetrates through the carriage along a substantially radial direction of the recording medium, and guides the movement of the carriage, and an oily material provided at a portion of the carriage that penetrates the guide shaft. A bearing that supports sliding with a guide shaft via a lubricant, a coil to which current is supplied, a magnet and a yoke that apply a magnetic field to the coil, and a magnetic circuit member that generates a driving force for the carriage; An optical system driving device comprising: a lubricant having a higher viscosity than the oil-based lubricant, and a lubricant filled in a gap between the coil and the yoke of the magnetic circuit member.

(4) The optical system driving device according to any one of (1) to (3) and (1) to (3), wherein the lubricant is grease.

(5) The optical system driving apparatus according to any one of (1) to (3) and (1) to (3), wherein the lubricant is a magnetic fluid.

[0040]

According to the present invention, the portion where the two parts between the moving carriage and the fixed portion are not in contact is filled with a viscous lubricant, and the portion supporting the carriage is filled. Since the viscous lubricant is not filled, the movement of the carriage is not deteriorated due to the high viscosity of the lubricant, and the lubricant reduces the external vibration, so that the adverse effect of the external vibration can be suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the first embodiment of the present invention.

FIG. 3 is a sectional view of the first embodiment of the present invention.

FIG. 4 is a perspective view of a second embodiment of the present invention.

FIG. 5 is a sectional view of a second embodiment of the present invention.

FIG. 6 is a perspective view of a third embodiment of the present invention.

FIG. 7 is a sectional view of a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 11 Carriage 14 Main bearing 15 Follower bearing 16a, 16b Bearing body 21a, 21b Guide shaft 22a, 22b Guide member

Claims (3)

[Claims] 1. A carriage to which an optical element is attached, a parallel guide shaft that penetrates the carriage along a substantially radial direction of a recording medium, and guides the movement of the carriage, and is provided at a portion of the carriage where the guide shaft penetrates. A bearing that supports sliding with the guide shaft; a shaft-shaped guide member that extends in a direction parallel to the guide shaft and penetrates the carriage; and a guide member that supports sliding between the guide shaft and the guide shaft. A bearing provided on the carriage so as to penetrate with a gap larger than a gap between the bearing and a lubricant having viscosity filled in a gap between the bearing and the guide member. Optical system driving device 2. A carriage to which an optical element is attached; a parallel guide shaft which penetrates the carriage substantially in the radial direction of the recording medium and guides the movement of the carriage; A bearing that supports sliding with a guide shaft, a plate-like guide member extending in a direction parallel to the guide shaft, and a slit provided in the carriage such that the guide member penetrates with a gap. An optical system driving device comprising a viscous lubricant filled in a gap between the slit and the guide member. 3. A carriage to which an optical element is attached; a parallel guide shaft which penetrates the carriage along a substantially radial direction of the recording medium and guides the movement of the carriage; A magnetic circuit member for generating a driving force for the carriage, comprising: a bearing for supporting sliding with a guide shaft; a coil to which current is supplied; a magnet and a yoke for applying a magnetic field to the coil; An optical system driving device comprising: a viscous lubricant filled in a gap between the coil and the yoke.