JP2001134966A - Objective lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve conventional problems that the number of parts and assembling processes is increased when the counter weight and the terminal part are fixed separately on a lens holder by bonding, press-fitting, welding, insert- forming or the like, because the counter weight is necessary for coinciding the gravity position of the movable part wit the center of support and drive and the terminal for soldering support members is necessary at the moval part side. SOLUTION: The counter weight 4a and the terminal part 4b are incorporated into one unit wit a metal plate 4, and then, the unit is integrally formed with the lens holder 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an objective lens driving device for an apparatus for optically recording or reproducing information on an information recording medium.

[0002]

2. Description of the Related Art There are two types of objective lens driving devices: a moving coil system in which a coil is provided on a movable portion, a magnet and a yoke are provided on a fixed portion, a magnet on a movable portion, and a coil and yoke are provided on a fixed portion. And a moving magnet system with Above all, the latter moving-magnet type objective lens driving device is frequently used for thin optical heads.

Conventionally, the movable portion of this type of objective lens driving device is configured as shown in an exploded perspective view shown in FIG.

[0006] That is, as shown in FIG. 6 (a), the objective lens 2 is attached to the lens holder portion 14 a of the lens holder 14.
A rectangular magnet 3 is mounted on the magnet holder 14b.
The counter weight 12 is fixed to the outer wall of the lens holder 14.

[0005] Further, as shown in FIG.
The magnets 3a and 3b are fixed at a position facing the yoke 21.

Further, the lens holder 14 and the holder 15 are provided with four support members 11a, 11b, 11c, 11d.
According to [see FIG. 6 (b)], it is fixed as shown in FIG. 6 (c).

That is, one ends of the support members 11a to 11d on the lens holder 14 side are fixed to a fixing plate 13 provided on the side surface of the lens holder 14, and the support members 11a to 11d
Is fixed to the side surface of the holder 15, so that the lens holder 14 forms a movable part.

Note that the upper surface of the objective lens 2 is
The protector 16 shown in FIG.

Next, as shown in FIG. 6D, a base 20 fixed between a light source (not shown) and an information recording medium (not shown) of the optical recording / reproducing apparatus has a magnetic material. A bobbin 24 in which a focusing control coil 22 and a tracking control coil 23 are wound is fixed around the yoke 21 which is a metal plate.

As shown in FIG. 6D, the fixing portions 25a and 25b of the substrate 25 are fixed to the fixing bosses 20a and 20b of the base 20.
Ob is fitted and fixed, and assembled as shown in FIG. At this time, as shown in FIG.
The lens holder 14 of the movable part is provided at a position where the lens holder 14 can move, with an appropriate gap provided for the lens holder 4.

In the above-described conventional example, when the light beam defocusing with respect to the information recording medium surface and the track deviation of the light beam with respect to the track groove on the information recording medium surface are detected, a current corresponding to the detection signal is detected. Focusing control coil 22 and tracking control coil 23
The objective lens 2 is moved up and down in the focusing direction, which is the direction of the objective lens optical axis, by utilizing the change in the magnetic flux in the magnetic field always formed between the magnets 3a and 3b and the yoke 21. The position of the objective lens 2 is controlled by driving the objective lens 2 in parallel with a tracking direction that is a direction perpendicular to the optical axis direction of the objective lens.

[0012]

However, while reducing the thickness of the movable portion of the optical recording / reproducing apparatus, ensuring linearity between the drive current and the displacement amount within the required movable range, and displacing DC. In order to reduce the amount of inclination of the movable portion, a counterweight for matching the position of the center of gravity of the movable portion with the support center and the drive center is required.

Further, a terminal portion for soldering the support member is also required on the movable portion side, and these are individually fixed to the lens holder by means such as bonding, press fitting, welding or insert molding. There are many parts and assembly steps.

[0014]

In order to solve this problem, in the objective lens driving device of the present invention, the counterweight and the terminal are integrally formed by a metal plate.

It is preferable that the metal plate is formed integrally with the lens holder.

According to the present invention, the number of components can be reduced by integrally forming the counterweight and the terminal portion with a metal plate, and the metal plate can be integrally formed by insert molding with a lens holder. In addition, the number of assembly steps can be reduced.

Further, by exposing only a part of the terminal portion on the surface of the lens holder, the soldering position of the support member can be stabilized.

Further, the strength of the lens holder is increased by the integrally formed metal plate, so that the higher-order resonance frequency of the frequency characteristic of the objective lens driving device is improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a side view of a movable portion of an objective lens driving device according to Embodiment 1 of the present invention, and FIG. 2 is a view of a movable portion of the objective lens driving device according to Embodiment 1 of the present invention. FIG. 3 is a sectional view taken along line AA of FIG. 1.

1 to 3, reference numeral 2 denotes an objective lens, and reference numerals 3a and 3b denote magnets. These components are the same as those of the conventional objective lens driving device described with reference to FIG.

Reference numeral 1 denotes a lens holder, and 4 denotes a metal plate insert-molded on the lens holder 1.
And a terminal portion for fixing the counter weight 4a configured so that the center of gravity of the counter weight coincides with the drive center P, and supporting members 11a to 11d (see FIG. 6) for supporting the lens holder 1 as a movable portion with solder. 4b and a reinforcing portion 4c which is insert-molded into a thin portion of the lens holder 1 are integrally formed to increase the strength of the lens holder 1.

As described above, in the first embodiment, the number of components can be reduced by integrally forming the counter weight 4a and the terminal portion 4b with a metal plate. In addition, the metal plate 4 in which the counter weight 4a and the terminal portion 4b are integrally formed is insert-molded into the lens holder 1, so that the number of assembling steps can be reduced.

(Embodiment 2) FIG. 4 is a perspective view of a metal plate insert-molded in a lens holder of an objective lens driving device according to Embodiment 2 of the present invention.

In FIG. 4, a notch 4d for reducing heat capacity is partially provided in a terminal portion 4b for fixing the supporting members 11a to 11d by soldering.

(Embodiment 3) FIG. 5 is a perspective view of a metal plate insert-molded in a lens holder of an objective lens driving device according to Embodiment 3 of the present invention.

In FIG. 5, the lens holder 1 including the terminal portion 4b is formed by embossing only the terminal portion 4b.
The strength of the thin portion is improved.

The counterweight 4a is formed by bending a single plate. If the bending position and length of the metal plate 4 are adjusted, the weight of the counterweight 4a can be adjusted.

By applying Sn plating or the like to the surface of the metal plate 4, the solderability when the supporting members 11a to 11d are fixed by soldering to the terminal portions 4b is improved.

The thickness of the metal plate 4 can be made substantially uniform, as shown in FIG. 5, even if the material different between the counter weight 4a and the terminal portion 4b is bent as shown in FIG. The material may be formed by bending.

[0031]

As described above, according to the present invention,
The number of parts can be reduced by integrally forming the counterweight and the terminal portion with a metal plate, and assembling is performed by insert-molding the metal plate with the counterweight and the terminal portion integrally formed on the lens holder. Man-hours can be reduced.

Also, by exposing only a part of the terminal portion to the surface of the lens holder, the soldering position of the support member can be stabilized.

In addition, since the strength of the lens holder is increased by the integrally formed metal plate, an excellent effect that the higher-order resonance frequency of the frequency characteristic of the objective lens driving device is improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a movable portion of an objective lens driving device according to a first embodiment of the present invention.

FIG. 2 is a front view of a movable portion of the objective lens driving device according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a perspective view of a metal plate of the objective lens driving device according to the second embodiment of the present invention.

FIG. 5 is a perspective view of a metal plate of the objective lens driving device according to the third embodiment of the present invention.

FIG. 6 is an exploded perspective view of a movable portion of a conventional objective lens driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens holder 2 Objective lens 3a, 3b Magnet 4 Metal plate 4a Counter weight 4b Terminal part 4c Reinforcement part 11a-11d Support member

Continued on the front page (72) Inventor Takayuki Kojima 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Inventor Noboru Hamaguchi 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference)

Claims (7)

[Claims] 1. An objective lens, a resin-molded lens holder for holding the objective lens, a magnet fixed to the lens holder, and a focus coil and a tracking coil installed at a position facing the magnet. , A bobbin wound with a wire, four or more supporting members for holding the lens holder, and a counterweight fixed to the lens holder to correct a shift between the center of gravity of the lens holder and the driving center position. And a terminal portion for fixing the support member to the lens holder by soldering, wherein the counterweight and the terminal portion are integrally formed of a metal plate. 2. The objective lens driving device according to claim 1, wherein the metal plate is formed integrally with the lens holder. 3. The objective lens driving device according to claim 1, wherein the terminal portion of the metal plate is formed in a thin portion to reinforce the rigidity of the lens holder. 4. The lens holder according to claim 1, wherein the metal plate is formed integrally with the resin of the lens holder, and only a part of the metal plate is exposed on the surface of the lens holder as the terminal portion.
The objective lens driving device as described in the above. 5. The objective lens driving device according to claim 1, wherein a plating process is performed on a surface of the metal plate. 6. The objective lens driving device according to claim 1, wherein the metal plate is formed by bending a material having a substantially uniform thickness. 7. The objective lens driving device according to claim 1, wherein the thickness of the metal plate is different between the counterweight and the terminal portion.