JPS60197945A - Objective lens holding device - Google Patents

Abstract

PURPOSE:To improve the response characteristic of an optical head by fixing and holding directly an objective lens to an elastic member such as a plate spring held so as to be deformed elastically freely in the tracking direction. CONSTITUTION:An objective lens holding device 16 is constituted of an objective lens 17, a pair of elastic members 18 for holding said lens, and a magnetic ring 19 fixed to the upper face part of the objective lens 17. The objective lens 17 is constituted of glass, etc., and on the outside of its effective diameter, a pair of supporting lug parts 20 are provided as one body by making its optical axis a symmetrical axis. On each supporting lug part 20, a hole 22 for inserting a plastically deformed part 21 of the elastic member 18 such as a plate spring is provided, and this hole 22 is made parallel to the optical axis of the objective lens 17, and has such a shape as can insert through the plastically deformed part 21 of the elastic member 18 so as to be fitted.

Description

[Detailed description of the invention] Technical field The present invention relates to an objective lens holding device for an optical head.

BACKGROUND ART In general, in a disc-shaped recording medium with concentric or spiral information tracks for recording or reproducing information, for example, an optical disc such as a video disc or a compact disc, while the recording medium is rotated at high speed, Usually, information is recorded or reproduced by irradiating a light spot onto an information track from an optical head consisting of a semiconductor laser serving as a light source and an objective lens converging the laser light from the semiconductor laser.

However, since the distance between adjacent information tracks on a recording medium is very narrow, the light spot, which is set to have a correspondingly small diameter, is likely to be relatively misaligned with respect to the track.

Therefore, in order to improve the precision of the optical head, it is necessary to control the relative positional deviation between the optical spot and the information track, that is, the tracking error, to be as small as possible, and tracking control is required for this purpose. This also requires that the objective lens holding device of the optical head be configured to enable tracking control.

Conventionally, as a device for holding an objective lens of an optical head to enable the above-mentioned tracking control, the configuration shown in FIGS. 1 and 2, for example, has been adopted. That is, the figure illustrates an optical information reading device 1 used as a recording/reproducing means, but as shown in the figure, an objective lens 2 is housed and held in a lens frame 3, and its optical axis is aligned with the light of the optical system. It should be aligned with the axis. The lens frame 3 is fixedly held on the free end side of a pair of plate blades 4 arranged parallel to the optical axis direction, and the proximal end side of the plate blade 4 is a cylinder having a through hole 5 for the optical path. It is fixedly held by a shape holding member 6. The plate 4 is configured to be elastically deformable in the tracking direction perpendicular to the optical axis direction, and therefore the objective lens 2 is also configured to be freely movable in the tracking direction via the plate 4.

A magnetic ring 1 made of a magnetic material is attached to the outer peripheral surface of the lens frame 3 of the objective lens 2. The objective lens 2 has a pair of magnetic rings 1 arranged around the magnetic ring 1 as shown in FIG. Permanent magnet 8,
8. Due to the excitation cooperation between the pair of tracking drive coils 8 and 9 and the magnetic ring 7, the tracking direction (movement in two directions) is controlled by an amount corresponding to the tracking error signal. The control structure is such that the tracking correction control of 2 can be performed.

In the figure, 10 is an outer frame of the apparatus, 11 is a coil for driving the objective lens 2, 12 is a leaf spring for supporting the holding member 6, 13 is a pair of yokes 14, 14, and a permanent magnet 8.
A holding frame 15 is a ring-shaped permanent magnet.

According to the holding device for the objective lens 2 as described above, the tracking drive coil 9,
By energizing 9, each coil 9.9 and permanent magnet 8
, 8. It is possible to displace the objective lens 2 in the tracking direction by the cooperative action with the magnetic ring 7, and the objective lens 2 can be controlled for tracking correction according to the tracking error signal.

However, the conventional objective lens holding device described above has the following problems.

(1) Generally, in order to improve the response characteristics of the tracking correction control described above, it is necessary to make the holding device for the objective lens 2 as small and lightweight as possible, but the conventional configuration described above requires a large number of parts. Moreover, since it is large and heavy, the response characteristics of tracking correction control are very poor.

(2) Due to the presence of the lens frame 3, processing the lens frame 3, assembling the objective lens 2 to the lens frame 3, etc. requires a great deal of effort.

This takes time, significantly reduces workability in assembly work, and increases the cost of the holding device.

Purpose of the Invention The present invention has been made in view of the problems of the prior art described above, and its purpose is to eliminate the need for the lens frame of the objective lens and to extremely simplify the assembly of the objective lens. The object of the present invention is to provide an objective lens holding device that solves the problems of the prior art described above.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a plastically deformable portion at a connecting portion with the objective lens in an elastic member that allows the objective lens to move in a tracking direction perpendicular to the optical axis direction. (2) The objective lens or the elastic member is equipped with a magnetic material or a permanent magnet.

Embodiments Hereinafter, embodiments of the present invention will be described in detail using the drawings from FIG. 3 onwards.

Figure 3 (a) = (b) t (c) - (') is
This shows the first embodiment of the present invention, and FIG. 3(a)
3 is a plan view of the objective lens holding device 16 according to the present invention.
Figure (b) is a cross-sectional view taken along line I-I in Figure 1 (a).
Figure (c) is an enlarged view of the part surrounded by circle A in Figure 1 (b1), and Figure 3 (d) is a partially enlarged view of the main part of the present invention. Figure 3 (a) .

As shown in (b), the objective lens holding device 16 includes an objective lens 17, which is an object to be held, and a pair of elastic members 18, which hold the objective lens 11 movably in the tracking control direction. , and a magnetic ring 1B made of a magnetic material fixed to the upper surface of the objective lens 11.

The objective lens 11 is made of resin such as glass or plastic, and outside the effective diameter of the objective lens 11, a pair of support ears 20 are provided as an axis of symmetry, which is the optical axis.
is provided integrally. Note that the support ear portion 20 is a separate body 1.
For example, the effective diameter portion of the objective lens 11 may be molded with a glass molding, and a supporting ear made of resin may be attached to the outer periphery of the effective diameter portion of the objective lens 11. A configuration in which the section 20 is actuated is also possible.

Each support ear is provided with a hole 22 through which the plastically deformed portion 21 of the elastic member 18 shown in FIG. 3(d) is inserted. Hole 22
is provided through the objective lens 11 in parallel to the optical axis direction,
The hole 22 is shaped so that the plastically deformed portion 21 of the elastic member 18 can be inserted therethrough in a fitting manner.

The elastic member 18 has a configuration in which its proximal end side (not shown) can be held by a holding member (not shown), and can be elastically deformed in the tracking direction when incorporated into the optical head. It is designed to be held in Elastic member 1
On the free end side of 8, that is, on the objective lens 17 holding side,
Elastic member 18. A plastically deformed part 21 is integrally formed with a narrower width than the main body of the objective lens 17 via a step part 23.
It has a structure that allows it to be inserted freely into 2. When the stepped portion 23 of the heavily deformed portion 21 is inserted into the hole 22 of the objective lens 17, it comes into contact with the support ear portion 20 of the objective lens 11 and the insertion force is restricted. 23, the support ear 20, and force 1 contact each other, as shown in FIG. It is configured to stand out.

The protrusion in the plastically deformed portion 21 is shown in FIG. 3(a).

As shown in (b) and (c) ζ2, the objective lens 17
The objective lens 17 is bent (plastically deformed) in the outward radial direction, and movement of the objective lens 17 in the optical axis direction is regulated via the bent portion 21a, so that the objective lens 17 is reliably attached to the elastic member 18. Configure settings so that they are retained.

In addition, the width and protrusion amount of the bent portion 21a, which is the actual plastic deformation portion! , shape, etc. can of course be set arbitrarily.

The magnetic ring 19 is fixedly mounted on the upper surface of the outside of the effective diameter of the objective lens 17 by means of adhesive or the like, and when the objective lens 11 is assembled into an optical head, a tracking drive (not shown) is provided. The movement of the objective lens 11 in the tracking direction can be controlled in cooperation with a storage coil and the like. The magnetic ring 19 may be fixed to the elastic member 18, or may be made of a permanent magnet. Also,
Instead of the magnetic 33119, a magnetic material portion can be formed in place of the magnetic ring 19 by depositing a magnetic material on a portion outside the effective diameter of the objective lens 11, or by applying and curing an adhesive mixed with a magnetic material or magnetic powder. It may also be a configuration in which it is formed.

In short, the magnetic ring 19 may be of any type as long as it can control the tracking correction of the objective lens 17 according to the tracking error signal by excitation cooperation with the tracking control drive unit (see FIGS. 1 and 2). Moreover, the magnetic ring 19 is
It may also be configured to be fixed to the outer periphery of the objective lens 11.

According to the above configuration, the objective lens 17 is fitted into the plastically deformed portion 21 of the elastic member 18 through the hole 22, and the protruding portion protruding from the hole 22 is bent in the radially outward direction of the objective lens 17. The objective lens 11 equipped with the ring 19 can be fixed and held directly to the elastic member 18.

As a result, the conventional lens frame is no longer necessary, and the number of parts and weight can be reduced, and the device can be made more compact and cost-effective. Furthermore, since the weight of the holding device 1B can be reduced, response characteristics during tracking control are improved, and accuracy during recording or reproduction in the optical head is improved. In addition, since the objective lens 17 can be fixed and held simply by fitting the hole 22 of the objective lens 17 into the plastically deformed portion 21 of the elastic member 18 and bending the protrusion from the hole 22, assembly of the objective lens 11 is extremely easy. This makes it easier and improves workability in assembly work.

Work time can be shortened and costs can be reduced.

Further, since the hole 22 of the objective lens 17 is fitted into the plastically deformed portion 21 and the objective lens 17 is fixed via the bent portion 21a, the objective lens 17 can be accurately positioned with respect to the elastic member 18, and A sufficient lens holding force is also ensured by the action of the bent portion 21a.

A second embodiment of the objective lens holding device 16 according to the present invention is shown in FIGS. 4(a), (b), (c), and (d).

The feature of this embodiment is that the elastic member 1 for holding the objective lens 17
The plastic deformation part 21 at B is shown in the figure as a particularly narrow part 2
Two holes 24 are formed in the deformable pieces 21b, 21b of the book, and on the supporting ear part 20 side of the objective lens 11 corresponding to the deformable pieces 21b, 21b, the two holes 24 are fitted with the deformable pieces 21b, 21b. 24 is constructed by penetrating each support ear portion 20. Then, at the top of the 6-hole 24, as shown in FIG.
As shown in (an enlarged view of the part surrounded by circle B in FIG. 3(b)), a tapered part 25 with an upwardly enlarged shape is formed, and a penetrating protrusion of each deformable piece 21b is formed in this tapered part 25. The objective lens 17 is fixedly held on the elastic member 18 by suppressing plastic deformation (so-called caulking operation). Note that although two deformable pieces 21b are protruded, there may be two (not limited to two, one or more pieces may be used).Also, the deformable piece 21b has a thickness approximately equal to that of the elastic member 1B. Although the shapes are circular with the same diameter, they may have a rectangular cross section or other shapes.The other configurations are the same as in the first embodiment, so the same members are designated by the same reference numerals. Therefore, the explanation will be omitted.

The functions and effects of the above configuration are the same as those of the first embodiment, so the explanation thereof will be omitted.

A third embodiment of the objective lens holding device 16 according to the present invention is shown in FIGS. 5(a), (b), (c), and (d).

The features of this embodiment are as shown in Fig. 5 (a), (b), (
As shown in c), an elastic member 18 for holding the objective lens
A recess 26 is formed in the center of the upper part of the lens, and both protrusions formed by the recess 26 are formed in the plastically deformed part 21. At the same time, an elastic member 18 is attached to each support ear 20 of the objective lens 11. This is because a groove portion 27 into which the plastically deformed portion 21 is fitted is formed. The width W1 of the thick part between the grooves 21 of the support ear 20 is the width W of the recess 26 of the elastic member °1B! The width of the groove portion 21 is set to be approximately the same as the thickness of the plastically deformed portion 21 of the elastic member 18. Further, the length of the plastically deformed portion 21 is as shown in FIG. 5(c).
When the supporting ear portion 20 is fitted into the recess 26, the plastically deformed portion 2
1 is set so that it protrudes from the upper surface of the support ear part 20 by an appropriate amount. For other configurations, please refer to the first section above.
Since this embodiment is the same as that in the embodiment, the same members are given the same reference numerals and their explanations will be omitted.

According to the above configuration, the objective lens 17 is sometimes assembled by bending the plastically deformed portion 21 protruding by the protrusion amount A in the radial outward direction of the objective lens 17.
This makes it possible to maintain a fixed position.

Other functions and effects are the same as those of the first embodiment, so their explanation will be omitted.

Figure 6 (a), (b), (c), (d)
= (e) shows a fourth embodiment of the objective lens holding device 1B according to the present invention. The features of this embodiment are as follows:
Both side surfaces 20a of each support ear portion 20 of the objective lens 11,
20 m is formed into a tapered surface, and a plastically deformable portion 21 is formed on one upper part of the elastic member 18 so as to wrap around the support ear portion 20a. The plastically deformed portion 2-1 is shown in Fig. 6 (
As shown in c), (d), and (e), an upper surface covering portion 21a that covers the upper surface of the support ear portion 20, and a side surface covering portion that covers both side surfaces 20a and 20a of the support ear portion 20. 21b, 21b, and a lower surface covering portion 21c that covers the lower surface of the support ear portion 20, which is shown in FIG. 6(c).
) As shown in FIG. 6, each part is first formed in a developed view, and the dotted line parts are bent and formed, so that the covered parts 21a, 21b, and 21c shown in FIG. 6 are formed. ing. For other configurations, please refer to the first
Since this embodiment is the same as that in the embodiment, the same members are given the same reference numerals and their explanations will be omitted.

According to the above configuration, the holding area of the objective lens 17 is increased, and there is an effect that the objective lens 17 can be held more reliably.

Other functions and effects are the same as those of the first embodiment, so their explanation will be omitted.

FIG. 7 shows a fifth embodiment of an objective lens holding device 1B according to the present invention. The feature of this embodiment is that the supporting ear portion 20 of the objective lens 20 and the plastically deformed portion of the elastic member 18 (
This is because an elastic member 2B made of rubber or the like is interposed between the bent portion 21 and the bent portion 21. The rest of the structure is the same as that of the first embodiment, so the same members are given the same reference numerals and their explanations will be omitted.

According to the above configuration, it is possible to prevent the objective lens 11 from being deformed when the plastic deformation section 21 is deformed.

Other functions and effects are the same as those of the first embodiment, so their explanation will be omitted.

FIG. 8 shows a sixth embodiment of the objective lens holding device 16 according to the present invention. The feature of this embodiment is that the objective lens 1 comes into contact with the plastically deformed portion 21 in the elastic member 18.
The first supporting ear portion 20 is formed into a U-shape, and a hollow portion 29 is provided.

Since the other configurations are the same as those of the first embodiment, the same members are given the same reference numerals and their explanations will be omitted.

According to the above configuration, deformation of the objective lens 17 during the deformation operation of the plastic deformation part 21 can be prevented by elastic deformation of the support ear part 20. Other functions and effects are the same as those of the first embodiment, so their explanation will be omitted.

What is shown in FIGS. 9 and 10 is the seventh column of the objective lens holding device 16 according to the present invention. This is an eighth example.

The feature of this embodiment is that both lenses 17 and 30
.

31 is retained and configured. That is, the one in Figure 9 is
A plurality of lenses 17, 30.

31 can be held. 10 is constructed so that a predetermined air gap is maintained by the leg portion 31m of the lens 31 instead of the spacer 32 in FIG. 9. In both embodiments, the magnetic ring 19 is fixed to the outer peripheral surface of the lens 31. Further, the supporting ear portion 20 may be omitted from any of the cemented lenses 11 and 30 in each embodiment.

According to the above configuration, there are a plurality of lenses 17 and 30.

31 can be easily fixed and held, and the other functions and effects of the structure 9 are the same as those of the first embodiment, so their explanation will be omitted.

Effects of the Invention As described above, the present invention has a structure in which the objective lens is fixed and held directly to an elastic member such as a leaf spring that is held so as to be elastically deformable in the tracking direction, so a lens frame is not required and the weight is reduced. This makes it possible to reduce the amount of damage caused by the optical head, and to significantly improve the response characteristics of the optical head. In addition, since the objective lens can be fixed and held simply by plastically deforming the elastic member, the assembly work is extremely easy, which improves the workability of the assembly work, reduces work time, and reduces assembly costs. There is an effect.

[Brief explanation of the drawing]

Figures 1 and 2 are a plan view and a vertical sectional view of an optical information reading device equipped with a conventional objective lens holding device, and Figure 3 (a).
is a plan view of the first embodiment of the present invention, and FIG. 3(b) is a plan view of the third embodiment of the present invention.
3(e) is an enlarged view of the interior in FIG. 3(b), FIG. 3(d) is a front view of the main part of the present invention, Figure (a) is a plan view of the second embodiment of the present invention, and Figure 4 (b) is the - in Figure 4 (a).
■A cross-sectional view of the line, Figure 4(C) is an enlarged view of the interior of Figure 4(b), Figure 4(d) is the same as Figure 4(a) and (b)
Front view of the main parts of Figure 5 (a), (b), (c
), (d) is an explanatory diagram of the third embodiment of the present invention,
Figures (a), (b), (c), (d),
(e) is an explanatory diagram of the fourth embodiment of the present invention, FIGS.
figure. FIGS. 9 and 10 show the fifth aspect of the present invention. 6th. 7th and 8th
FIG. 11...Objective lens 18...Elastic member 19...Magnetic ring 20...Support ear part 21...Plastic deformation part Fig. 4(c) (d) Only 1b Fig. 5(G) 7 Figure 6 (G)

Claims (1)

[Scope of Claims] (1) An objective of an optical head that irradiates a light spot to record or reproduce information on a disc-shaped recording medium having concentric or spiral information tracks for recording or reproducing information. In the lens holding device, a plastically deformable portion is provided at a connecting portion with the objective lens in an elastic member that holds the objective lens movably in a tracking direction perpendicular to the optical axis direction thereof, and An objective lens holding device, characterized in that the objective lens is held by the elastic member, and the objective lens or the elastic member is equipped with a magnetic body or a permanent magnet. (2) An apparatus characterized in that the plastically deformable portion of the elastic member is constituted by a bendable protrusion inserted into a hole provided outside the effective diameter of the objective lens. (3) The plastically deformable portion of the elastic member is constituted by an appropriate number of protruding plastically deformable pieces that can be freely inserted into an appropriate number of holes provided outside the effective diameter of the objective lens. An objective lens holding device according to claim 1. (4) A patent characterized in that the plastic deformation portion of the elastic member is comprised of protrusions formed on the left and right sides of a recess that fits into a groove provided outside the effective diameter of the objective lens. An objective lens holding device according to claim 1. (5) The plastically deformable portion of the elastic member is configured to be plastically deformable so as to cover a support ear provided outside the effective diameter of the objective lens. Objective lens holding device as described in Section 1. (6) An elastic member is interposed between the plastic deformation portion of the elastic member and the objective lens. 2. The objective lens holding device according to claim 1, wherein the connecting portion of the elastic member with the severely deformable portion is configured to be elastically deformable in an operating direction that deforms the plastically deformable portion. (8) The objective lens holding device according to claim 1, wherein the plastically deformed portion of the elastic member is configured to be able to hold a plurality of lenses.