JPH02105338A - Objective lens driver for information recorder - Google Patents

Abstract

PURPOSE:To prevent the flaws of an objective lens and an optical disk caused by the contact between them and to secure the rotary sliding characteristics by using a material softer than the surface of the optical disk to a cap put on a mobile holder and setting the upper surface of the cap at a position near the disk. CONSTITUTION:When the impact force caused by the failure of the initial lead-in at start of a focus servo action is applied to an objective lens driver 22 and therefore the driver 22 tries to extraordinarily move up, a cylindrical cap 23 touches an optical disk 21. Therefore an objective lens 1 does not touch the disk 21. The disk 21 is never impaired with touch to the cap 23 since this cap is made of the hard rubber softer than the material of the disk 21. The cap 23 is fixed at the upper part of a bearing 3 as if it covered a support shaft 13. Thus it is possible to avoid the deterioration of the rotary sliding characteristics of a mobile holder 2 that is caused by the dust mixed from the upper part of the bearing 3.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an objective lens used for reproduction or recording in an information recording device, which controls track deviation and defocus of a light spot focused on an information recording surface. This relates to a drive device.

[Prior Art] A conventional objective lens driving device of an information recording apparatus will be explained with reference to FIGS. 5 to 8. In the figure, 10 is a base yoke that is a base material, and this base yoke 10 has a support shaft 13 implanted in the center and rising pieces 11a that protrude upward from both side ends.

1], b. 2 is a bearing 3 on the support shaft 13.
in the axial direction of the support shaft 13 (arrow A
The movable holder 20a, 20b includes an objective lens 1 that is slidably provided in the direction (direction) and has an optical axis parallel to the axis of the support shaft 13, and a counterweight 25, and the movable holder 2 is rotated. A track control drive section 30 is a focus control drive section that drives the movable holder 2 in the axial direction. The track control driving parts 20a and 20b are rectangular track control coils 7a fixed to mounting parts 6a and 6b on both side surfaces of the movable holder 2.

7b, and the rising piece 11a of the base yoke 10.

Permanent magnets 12a and 1 for track control are provided in 11b so as to face the track control coils 7a and 7b.
2b. the track control permanent magnet 12a;
12b is configured such that the directions of magnetic flux vectors interlinked between one side of the objective lens 1 that is approximately parallel to the optical axis and the other side, that is, the side on the side of the track control coils 7a and 7b and the outer side, are reversed. It is magnetized with two poles. The focus control drive section 3
0, the support shaft 1 is attached to the lower mounting portion 4 of the movable holder 2.
A link-shaped focus control coil 5 provided so as to surround 3.
and arcuate focus control permanent magnets 9a and 9b provided on the yoke 8 of the base yoke 10 so as to face the focus control coil 5. The permanent magnet 9 for focus control
a and 9b are magnetized in the radial direction, that is, in the direction perpendicular to the axis. 14 is a support rubber which is an elastic material that holds the movable holder 2 in a neutral state;
Support rubber attachment portions 17a provided at both ends of the support rubber attachment portions 17a.

Movable side mounting pieces 15a, 15b fixed to 17b, -
The rising piece 11a of the base yoke 10.

The base yoke 10 is integrally formed with fixed side mounting pieces 16a to 16d fixed to supporting rubber mounting parts 18a to 18d provided on the base yoke 11b, and elastically connects the base yoke 10 and the movable holder 2. .

The above constitutes the objective lens driving device 22 of the information recording device. Reference numeral 21 denotes an optical disk which is an information recording medium. This optical disk 21 is molded from polycarbonate, is placed on the side of the objective lens moving device 22, and is rotated by a motor or the like.

Next, the operation will be explained. By passing a control current in accordance with the amount of focus shift through the focus control coil 5, the movable holder 2 slides in the direction of arrow A, changing the distance between the objective lens 1 and the optical disc 21 to perform focus control. Also,
By passing a control current in accordance with the amount of track deviation to the track control coils 7a and 7b, the movable holder 2 moves toward the arrow B.
The objective lens 1 is rotated in the direction to control the tracking of the objective lens 1. When the current flowing through the track control coils 7a and 7b is turned off, the movable holder 2 is rotated by the support rubber 14 and returned to the neutral state and held there. A light beam emitted from a light emitting device (such as a semiconductor laser) (not shown) is emitted onto the optical disk 21 via the objective lens driving device 22 whose focus and track are controlled in this way,
The reflected light beam is read by a reproducing device (not shown). Further, the output light beam is used to record information on an optical disk.

[Problems to be Solved by the Invention] Since the objective lens driving device of the conventional information recording device is configured as described above, as shown in FIG. When some kind of impact force is applied, the movable holder 2 moves up too much, causing the objective lens 1 to come into contact with the optical disc 21, resulting in damage to the objective lens 1 and the optical disc 21.

This invention was made to solve the above problems, and provides an objective lens for an information recording device that can prevent damage caused by contact between the objective lens and an optical disk by regulating the sliding movement of a movable holder in the light output direction. The purpose is to obtain a driving device.

[Means for Solving the Problems] An objective lens drive device according to the present invention is provided with a stopper that limits the sliding range in the light emission direction to a certain range when the movable holder slides in the axial direction. It is.

[Function] The objective lens driving device of the present invention prevents the movable holder from sliding too much and causing contact between the objective lens and the optical disk, by a stopper that limits the sliding range of the movable holder in the axial direction to a certain range. do.

[Embodiment] An objective lens driving device for an information recording apparatus which is an embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Components that are the same as those in FIGS. 5 to 8 are designated by the same reference numerals, and the description thereof will be omitted. In the figure, a cylindrical cap 23 is made of hard rubber that is softer than the material (polycarbonate) of the optical disc 21, and is fixed to the upper part of the bearing 3 so as to cover the support shaft 13. Further, the upper surface of the cap 23 is located above the upper end of the objective lens 1, and the optical disc 21 is placed from the upper end surface of the cap 23.
The distance from the objective lens 1 to the optical disc 21 is set shorter than the distance from the objective lens 1 to the optical disk 21 (working distance of the objective lens 1).

Next, the operation will be explained. This objective lens drive device 2
Even if the cap 23 tries to move upward abnormally due to an initial pull-in failure when starting the focus servo or an impact force is applied to the focus servo, the cap 23 comes into contact with the optical disk 2'' as shown in FIG. is regulated. That is, the objective lens 1 does not come into contact with the optical disc 21. Furthermore, since the cap 23 is molded from hard rubber, it does not damage the optical disc 21 and softens the impact force generated when it comes into contact with the optical disc 21, thereby alleviating the impact on the device. Can be done.

Moreover, since it covers the support shaft 13, it is possible to prevent deterioration of the rotation and sliding characteristics of the movable holder 2 due to dirt entering from above the bearing 3.

In this embodiment, the cap 23 is molded from a hard comb, but the cap 23 is not limited to this.
Any material that is softer than material 1 and does not cause damage may be used.

In addition, in this embodiment, a cap 2 is provided on the upper part of the bearing 3.
3 is provided to restrict the sliding range of the movable holder 2 in the light output direction to a certain range, but as shown in FIG. However, a flange 13a may be provided at the upper end of this support shaft 13, and the sliding range of the movable holder 2 in the light emission direction may be restricted to a certain range by the flange 13a. A stopper may be installed to restrict the sliding range in the light emission direction.

[Effects of the Invention] As described above, according to the present invention, the objective lens driving device of the information recording device is provided with a stopper that restricts the sliding range of the movable holder in the light emission direction to a certain range. Damage to the objective lens and optical microscope due to excessive sliding can be prevented, and a highly reliable device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view of an objective lens driving device of an information recording apparatus which is an embodiment of the present invention, FIG. 2 is a sectional view taken along the line Ir in FIG. 1, and FIG. 3 is a side sectional view of the objective lens driving device. , FIG. 4 is a side cross-sectional view of an objective lens drive device of an information recording device according to another embodiment, FIG. 5 is a side sectional view of an objective lens drive device of a conventional information recording device, and FIG. Figure 7 is the 5th
FIG. 8 is a plan view of an objective lens driving device of a conventional information recording apparatus. 1. Objective lens, 2.. Movable holder, 10.. Base yoke, 13.. Support shaft, 14.. Support rubber, 2
0a, 20b... Track control movement section, 21 optical disk, 22... Objective lens drive device, 23. Cap, 30... Focus control drive section.

Claims (1)

[Claims] a movable holder provided with an objective lens rotatably and slidably in the axial direction on a support shaft implanted in a base material and having an optical axis parallel to the axis of the support shaft; and the movable holder. In the objective lens driving device of an information recording device, the objective lens driving device of an information recording device comprises a driving part that rotates and drives the movable holder in the axial direction, and an elastic member that connects the base material side and the movable holder side and holds the movable holder in a neutral state. 1. An objective lens drive device for an information recording device, characterized in that a stopper is provided for regulating a sliding range in a light emission direction to a certain range when a movable holder slides in an axial direction.