JPH01317235A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To reduce the friction and to improve the response of an objective lens driving device by providing the movable bearings on the upper and lower end faces of a lens holder so as to reduce the contact area between said bearings and a pivot. CONSTITUTION:The movable bearings 15a and 15b are provided to the upper and lower end faces set approximately at the center part of a lens holder 3. Both bearings 15a and 15b have the cylindrical structures of aluminum, for example, and provide the upper and lower tapers in order to eliminate the catching at the edge of the bearing 15a. The taper angle is preferably set at about 30 deg. against the lengthwise direction of a pivot 4. At the same time, the bearing 15b is treated in the same way as the bearing 15a. As a result, the contact area is reduced between the pivot 4 and both bearings 15a/15b together with reduction of the friction. Then the response is improved for an objective lens driving device.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is an objective lens driving device, in particular, a system for controlling trunk deviation and defocus of an original spot focused on an information recording surface of an optical disk. The present invention relates to an objective lens driving device for a reproducing device or a recording/reproducing device.

[Conventional technology]

Conventionally, as this type of objective lens driving device, there is one called an axial sliding rotation type objective lens driving device shown in the fourth to sixth cases. 2 is a counterweight, and 3 is a lens holder having a movable shaft 93a and a focus control coil bobbin 3b. Reference numeral 4 denotes a support shaft, on which the driving bearing grip is fitted so as to be freely rotatable in the rotational direction and slidable in the axial direction. 5 is a tambour that holds the lens holder 3, 6 is a permanent magnet for focus control, 7a, 7k) is a permanent magnet for track control, 8 is a yoke that also serves to hold and align the support shaft 4 and the permanent magnet 6 for focus control, 9a , 9b is a track control yoke, 10 is a focus control filter, 11a and 11b are trunk control coils, 1
2a, h are damper fixing bins for fixing the damper, 13
Reference numeral 14 denotes a fixing base for erecting and supporting damper orientation pins, and 14 a dustproof cover.

In the objective lens drive device with the above configuration, the cylindrical movable bearing 3a is fitted to the support shaft 4, so the lens holder 3
It is supported slidably in the longitudinal direction of the support shaft 4, that is, in the direction of arrow B in FIG. 6, and rotatably supported around the support shaft 4 in the direction of arrow A in FIG. . Here, by applying a desired current to the focus control filter 10,
The focus can be controlled by moving the lens holder 3 in the direction of arrow B, and since the objective lens 1 is fixed to the lens holder 3 at a predetermined distance from the support shaft 4, Trunk control can be performed by applying a desired current to the trunk control coils 11a and 11b and rotating the objective lens 1 in the direction of the arrow.

[Problems that the invention attempts to solve]

By the way, in the above-mentioned shaft sliding rotation type objective lens support system, the friction existing between the movable bearing 3a and the support shaft 4 affects the operation of the opening J#J part of the objective lens drive device. It is known. Next, an example of how this friction affects the operation of the movable part will be explained using FIG. 8.

FIG. 3 is a diagram showing the response displacement of the movable part to a low frequency input current of several meters.

a is the input, b is the response displacement when the friction is small, and C is the response displacement when the friction is large. In the low frequency region, when there is friction, there is a time period Ts in which the movable part does not operate, as shown in Figure 3C, and this time period T8 is determined by the poor j response of the movable part. , and l
The larger ilJm is, the larger Ts is.

This invention was made to improve the poor responsiveness of the movable part due to friction as described above, and an object of the present invention is to obtain an objective lens drive device with reduced friction and good responsiveness.

[Means to solve the problem]

In the objective lens drive device according to the present invention, movable bearings are disposed on both ends of the lens holder F so that the contact area between the movable bearings and the support shaft is small.

[Effect]

In this invention, the contact area with the CW% movement bearing shaft is reduced, and friction can be reduced, thereby improving the responsiveness of the objective lens driving device.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a partial sectional view showing one embodiment of the present invention, and FIG. 2 is an enlarged view of the main part thereof. In the figure, 15a and 15b are of the lens holder 3! These are movable bearings arranged on the upper and lower end surfaces of the central portion.

It should be noted that other parts with the same reference numerals as those in the conventional example indicate members that are the same or correspond to those in the conventional example, and therefore the description thereof will be omitted.

Here, the function of the bearing section will be explained using FIG. 2. The movable bearing 15a has a cylindrical structure made of aluminum, for example, and is disposed on the upper end surface of the lens holder 3.
As shown in the figure, tapers are provided from both the top and bottom directions.

This is to prevent the movable bearing 15a from being caught by the edge, and the angle of the taper is preferably about 80 degrees with respect to the longitudinal direction of the support shaft 4. '8fT, knee, and support shaft 4 are preferably made of 8US coated with low-friction Teflon thread resin.

Note that a movable bearing 15 disposed on the lower end surface of the lens holder 3
Regarding 1), it is the same as the movable bearing 15a disposed on the lower end surface, and the explanation thereof will be omitted here.

As described above, the contact area between the support shaft 4 and the movable bearings 15a, 15b can be made considerably smaller than in the past.
As shown in the figure, an objective lens driving device with a small Ts and good responsiveness can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the movable bearing is
To provide an objective lens drive device with good responsiveness by reducing friction between the movable bearing and the support shaft by arranging two Q ends and arranging the structure so that the contact area between the movable bearing and the support shaft is small. There is an effect that can be done.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of one embodiment of the present invention, Fig. 2 is an enlarged view of its main parts, and Fig. 8 a, b, and c are human-powered
Figures 4 to 6 show an example of a conventional objective lens driving device, and Figure 4 is an exploded perspective view thereof, Figure 5 is a partial plan view, and Figure 6 is a diagram showing the response displacement of the movable part to the flow. is a sectional view taken along the line ■-■ in FIG. In the figure, IG:z objective lens, 3 is a lens holder, 4 is a support shaft, and 15a, ]5b are movable bearings. In the past, the same numbers in the figures indicate the same or corresponding parts.Masuo Oiwa Figure 3 Procedure Amendment (Voluntary) 1. Indication of the incident: Patent Application No. 150487/1987 2,
Title of the invention: Objective lens drive device 3; Relationship with the person making the amendment; Moriya Shiki, representative of the patent applicant; 5; Detailed description of the invention in the specification to be amended; 6; Contents of the amendment ( 1) [2 pieces arranged at the top and bottom ends] on page 6, line 11 of the specification
is corrected to "disposed on both the upper and lower end faces, respectively."that's all

Claims (1)

[Claims] a movable bearing fitted to a support shaft so as to be movable in a rotational direction and an axial direction; an objective lens having an optical axis parallel to the axial direction of the support shaft; and a lens holder that holds the movable bearing and the objective lens. , a drive device attached to the lens holder and driving the lens holder in a rotational direction and an axial direction, so as to be able to control track deviation and defocus of a light spot focused on a disk via the objective lens. An objective lens drive device according to the present invention, wherein movable bearings are disposed on each of the upper and lower end surfaces of the lens holder.