JP2614499B2 - Actuator for optical disk - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive for driving an optical beam spot on a disk in a two-dimensional direction in an optical disk device.

[Conventional technology]

FIG. 4 is a plan view schematically showing a shaft sliding type actuator which is one of the conventionally used optical disk actuators. In FIG. 4, reference numeral 5 denotes a movable portion having a deformed hexagonal shape in which a pair of opposing sides is long.
That is, the objective lens 1 is fixed to one of the sliding shafts 9 attached to the lower surface of the center of the bobbin 5 in the longitudinal direction of the irregular hexagon of the bobbin 5, and the sliding shaft 9 is attached to the other. The balancer 2 is disposed so as to be the center of gravity of the balancer 5. The bobbin 5 is vertically and rotatably fitted to a bearing (not shown) by the sliding shaft 9. Thereby, the objective lens 1 of the bobbin 5 can be moved in a direction perpendicular to the disk surface as a disk-shaped recording medium, that is, in a focus direction, or in a track direction of the disk surface.

On the other hand, in the lower part of the bobbin 5, a cylindrical focusing coil 3 indicated by a broken line and a tracking coil (not shown) are wound around the sliding shaft 9 as a center axis.

Further, a magnet is provided around the sliding axis 9 of the center axis of the coil 3.
7a and 7b are located 180 ° apart in a direction perpendicular to the longitudinal direction of the bobbin 5. Tracking control in this shaft sliding type actuator is performed by using the sliding shaft 9 as a central axis.
The bobbin 5 on which the objective lens 1 is disposed is moved in the track direction on the disk surface by the electromagnetic force generated between the tracking coil 4 also disposed on the bobbin 5 and the magnets 7a and 7b, that is, the white arrow direction in FIG. It is performed by turning to. Therefore, the shaft sliding type actuator has an advantage that unnecessary vibration is hardly generated in tracking control.

[Problems to be solved by the invention]

However, as described above, the conventional sliding shaft type actuator has a disadvantage that it is necessary to dispose the objective lens 1 and the balancer 2 on both sides of the sliding shaft 9 and it is difficult to reduce the size. That is, in the case of the shaft sliding type actuator, if the diameter of the focusing coil is d, the diameter of the objective lens 1 is Ld, and the diameter of the balancer is 1, d + Ld +
The length of l is essential.

The present invention has been made in view of such circumstances, and provides a miniaturized optical disk actuator by fitting a movable portion to a bearing rotatably and fixing an objective lens inside a signal position of the movable portion. The purpose is to:

[Means for solving the problem]

An optical disk actuator according to the present invention includes: a movable part that is a cylindrical bobbin that holds a lens to be made to face an optical disk; and a cylindrical bearing that rotatably fits the movable part. In, the outer peripheral surface of the movable portion and the inner peripheral surface of the bearing are fitted with each circumferential surface as a sliding surface, and the objective lens is held inside such a fitted position, A plurality of tracking coils are disposed on an outer peripheral surface of the movable portion, and a sliding surface of the movable portion slides on the bearing by an electromagnetic force generated between a magnet provided outside the bearing and the tracking coil. Rotating along the moving surface.

[Action]

In the present invention, since the objective lens is held inside the position where the movable part of the movable part and the bearing are fitted, the objective lens held by the movable part with the rotation of the movable part is Moves in the track direction on the disk surface.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings showing the examples.

FIG. 1 is a perspective view schematically showing one example of an optical disk actuator according to the present invention. FIG. 1 (a) shows the structure of a bobbin which is a movable portion, and FIG. 1 (b) shows the structure of the bobbin. The structure around a bearing is shown. 2 and 3
The figures are a plan view and a bottom view of the bobbin, respectively.

In FIG. 1A, reference numeral 5 denotes a cylindrical bobbin having an upper bottom, on which the objective lens 1 is fixed at an eccentric position of the bobbin 5. The balancer 2 is disposed on the upper bottom so as to be positioned so that the center of gravity of the bobbin 5 coincides with the geometric center. Focusing coil 3 is provided on the outer peripheral surface of bobbin 5.
, And a plurality of tracking coils 4 are arranged on the outside thereof. On the inner peripheral surface of the bobbin 5, a sliding surface 8 is formed in the circumferential direction of the bobbin 5. A bobbin 5 is provided on the outer peripheral surface of the cylindrical bearing 6 shown in FIG.
A sliding surface 6a having substantially the same diameter as the sliding surface 8 is formed. The bobbin 5 and the bearing 6 described above are inserted and fitted so as to cover the bobbin 5 as shown by an outline arrow in FIG. Can be moved vertically and rotatably along the sliding surface 6a of the bearing 6. Further, at positions facing the focusing coil 3 wound around the outer peripheral surface of the bobbin 5, magnets 7a and 7b are provided at 180 ° apart.

 Next, the operation of the present invention will be described.

In the tracking control of the actuator according to the present invention, when a tracking correction current output from a tracking error detection circuit (not shown) is applied to the tracking coil 4, an electromagnetic force is generated between the tracking coils 4, 4 and the magnets 7a and 7b. Is generated, and the sliding surface 8 of the bobbin 5 rotates along the sliding surface 6a of the bearing 6, thereby eccentrically fixing the objective lens 1 from the center of the bobbin 5.
Moves in a predetermined track direction on the disk surface. Here, the bearing 6 also serves as a yoke for the magnet circuit. The light beam emitted from the light source (not shown) enters through the lower surface opening of the fitted bobbin 5 and the bearing 6, passes through the inside of the bearing 6, and passes through the lower surface side of the bobbin 5 to form the bobbin 5. After entering the upper-bottom objective lens 1 and condensing, it irradiates a predetermined track on the disk surface.

In this embodiment, the bobbin 5 which is a movable part is connected to the bearing 6.
Although the case where the bobbin 5 is used by fitting it outside is shown, the present invention is not limited to this, and the bobbin 5 may be used by fitting it inside the bearing 6.

Further, in this embodiment, the balancer 2 is disposed so as to be positioned so that the center of gravity of the bobbin 5 matches the geometric center. However, the present invention is not limited to this.
In place of the balancer 2, the weight required for the center of gravity of the bobbin 5 to coincide with the geometric center may be added or removed on the lower surface of the bobbin 5.

〔The invention's effect〕

As described in detail above, in the optical head actuator according to the present invention, the tracking control is performed by rotating the bobbin. Therefore, the moment generated by the high-speed access operation in the tracking control becomes zero, and unnecessary vibration is generated in principle. High-speed access can be performed with good performance. Further, since the objective lens can be fixed at a position eccentric from the center of the upper bottom of the bobbin inside the position where the bobbin and the base are fitted, the bobbin 5 is offset from the diameter Ld of the objective lens and the center of the bobbin 5. Only the total length up to the objective lens, which is fixed in mind, can save extra space,
For example, it is possible to reduce the size of actuators for optical discs.
The present invention has excellent effects.

[Brief description of the drawings]

FIG. 1 shows an optical disk actuator 1 according to the present invention.
2 is a plan view of a bobbin, FIG. 3 is a bottom view of the bobbin, and FIG. 4 is a plan view schematically showing a conventional actuator for an optical disk. DESCRIPTION OF SYMBOLS 1 ... Objective lens 2 ... Balancer 3 ... Focusing coil 4 ... Tracking coil 5 ... Bobbin 6 ... Bearing 6a ... Sliding surface of bearing 7a, 7b ...
Magnet, 8 ... Bobbin sliding surface

Claims (1)

(57) [Claims] 1. An actuator for an optical disk, comprising: a movable portion which is a cylindrical bobbin for holding a lens to be made to face an optical disk; and a cylindrical bearing which rotatably fits the movable portion. The outer peripheral surface of the portion and the inner peripheral surface of the bearing are fitted with each circumferential surface as a sliding surface, the objective lens is held inside such a fitted position, and the A plurality of tracking coils are provided on the outer peripheral surface, and a sliding surface of the movable portion moves along a sliding surface of the bearing by an electromagnetic force generated between the magnet provided outside the bearing and the tracking coil. An optical disc actuator, characterized in that the actuator rotates.