JPS605429A - Objective lens driver - Google Patents

Abstract

PURPOSE:To obtain a unique and useful lens driver which can satisfy the specifications of disk variance with a compact design, by using two mobile intermediate members and controlling the motion to a shaft in the revolving direction. CONSTITUTION:A symmetrical structure is obtained to a lens holder 5, and intermediate members 8 and 8 are supported by elastic matters 9 extended from fixing parts 6 and 6 at both sides. Then the holder 5 is supported by elastic matters 10 extended inside from members 8 and 8. In such a constitution, the movement to revolutions is controlled. This eliminate a matching mechanism for optical axes of a lens system. For tracking purpose, the current is supplied to coils 11 wound around four corners. Thus the left and right forces act on the area between yokes 13 and 13. While the current is flowed to a coil 12 wound around the entire circumference of the holder 5 for focusing purpose. Thus the up/down forces acting on the area between yokes 13 and 13 is utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an objective lens driving device for an optical pickup for recording and reproducing optical discs.

<Prior Art> For example, in a digital I'th disc or an IOD, it is necessary to drive a lens in the focusing direction and to track the vertical movement of the disc with an accuracy of within 2 μm of the depth of focus of the lens. In addition, in the track direction, the eccentricity that occurs in mechanical elements (for example, vibration of the motor shaft) is added to the eccentricity allowed for the disk of ±70 μm, and these amounts are used to configure the servo system. ±0.1μm
It is necessary to keep it below.

Furthermore, since the disc specifications allow a variation of ±0.5 degrees in the vertical direction of the disc, the lens must be able to move in the focus direction by more than ±0.5 degrees in terms of dynamic range.

In the conventional example shown in FIG. 1, a lens cylinder 3 supported by upper and lower 9 intermediate portions 2, 2 is movable vertically and horizontally in a fixed part 1 consisting of an integral yoke (partially cut out and shown with diagonal lines). A plurality of elastic bodies 4, 4. ... supports the lens cylinder 3. Movement up and down and left and right is achieved by passing current through the coil.

However, in this method, in order to satisfy the above-mentioned dynamic range of ±0.5 in the focus direction, the elastic bodies 4, 4. It becomes necessary to increase the size of the elastic body due to the relationship between... For audio discs, etc., in which information is written up to the center of the disc, the lens drive unit that faces the disc must be as small as possible, which has the disadvantage that it may not be possible to configure an optical pickup in some cases. .

FIGS. 2 and 3 show another conventional example, in which the lens holder 5 consists of an intermediate member 8 that is supported by elastic bodies 7, 7, . It is supported by flipping it inward.

With this method, the lens holder 5 is returned to the inside via the freely movable intermediate member 8, so that the entire structure can be made smaller. Moreover, the elastic bodies 7, 7. ...
Since the length of the torque can be made substantially longer, it is possible to realize a dynamic range that meets the audio disc specifications of ±0.5 or the video disc specifications of ±l #ll11.

In other words, since the amount of variation in the track direction is small,
As shown in Figure 2, the elastic body dimension m is the focus side dimension l.
There is no need to make the culm long, and therefore, a configuration in which the culm is returned to the inside via the intermediate member 8 as in this configuration is possible.

However, in the frame-supported type shown in FIGS. 2 and 3, the intermediate member 8 moves freely as shown in the perspective view of FIG. A rotational force in the direction of the arrow is applied to the lens support section. A rotational force in the direction of the arrow in the figure also acts on the B axis. these are,
This requires a fine adjustment mechanism to align the optical axis of the optical system with the optical axis of the lens when installing the lens, and also makes the operation unstable when the lens moves.

<Object of the invention> The present invention solves the conventional drawbacks as described above.
It is an object of the present invention to provide a compact and useful objective lens drive device that fully satisfies disk opening specifications.

<Embodiment> FIG. 4 is a perspective view showing one embodiment of the present invention, and FIG. 5 is a side view of the same. However, the magnetic circuit configuration is omitted in FIG. 4.

As shown in the figure, elastic bodies 9, 9, 9, 9, 9, and 9 have a symmetrical structure with respect to the lens holder 5, and extend from the fixing parts 6, 6 on both sides. ...
The lens holder 5 is supported by elastic bodies 10.1"0. . . which extend inward from the intermediate members 8.8.

With this configuration, compared to supporting only on one side in the previous example,
Since the rotational movement in the direction of the arrow in FIG. 3 is restricted, a mechanism for aligning the optical axis of the lens system becomes unnecessary.

Regarding the magnetic circuit, a carp 1vll for tracking shown in FIG. 6, 11. ...and by winding the coil 12 for focusing as shown in the figure, a set of magnetic circuits including the yokes 13 and 13,
It can give movement in both directions. In other words, the tracking reservoir contains carp/l wound around the four corners.
/11,11. By passing a current roughly through the coil 12 wound around the entire circumference, a left-right force is applied between the yoke 13.13 and the yoke 13.13. It uses the vertical force that acts between the

<Effects of the Invention> As described above, according to the present invention, two movable intermediate members are used to restrict movement in the rotational direction with respect to the shaft, and the invention is compact and novel and useful, satisfying the disc fluctuation specifications. It is possible to provide a lens driving device.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing a conventional example, Fig. 2 is a side view showing another conventional example, Fig. 3 is a perspective view thereof, and Fig. 4 is a perspective view showing an embodiment of the present invention. , FIG. 5 is a side view of the same, and FIG. 6 is an exploded perspective view of the main parts. 5... Lens holder, 6.・6... Fixed part, 8.
8... intermediate member, 9.9..., 10.10...
...Elastic body, 11, 11, 12, coil, 13, 13, yoke. 7? Tsukuda person Shinfudate forget 4- Eclipse / 4h? Evening 19 Figure 1 Figure 2cX1 Figure 3

Claims (1)

[Claims] 1. An intermediate member is supported diagonally to the lens holder by elastic bodies extending from fixed parts on both sides, and the lens holder is supported by elastic bodies extending inward from the intermediate members through the intermediate member, 1. 1. An objective lens driving device comprising a magnetic circuit configuration that allows movement in both track and focus directions using a pair of magnetic circuits.