Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specified detail of transducer assembly support structure
Reexamination Certificate
1998-02-04
2001-09-04
Dinh, Dung C. (Department: 2754)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specified detail of transducer assembly support structure
Reexamination Certificate
active
06285650
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for driving an optical pickup, and more particularly to a driving apparatus of an optical pickup capable of being further slimmed and obtaining more accurate operating characteristics while coinciding centers of an objective lens and a mover.
2. Description of the Prior Art
A driving apparatus of an optical pickup indicates a device which performs tracking and focusing control with respect to playback signals of a recording medium by moving a loaded objective lens up and down and right and left. At this time, the focusing denotes the operation of moving the objective lens up and down for permitting a spot of beam focused by the objective lens to be accurately focused onto a recording plane of a disc. Also, the tracking denotes the operation of moving the objective lens right and left for permitting the spot of focused beam to accurately trace a path of a track of an optical disc.
A conventional driving apparatus will be described with reference to
FIGS. 1A and 1B
. As illustrated, the driving apparatus includes a mover
1
loaded with an objective lens
2
thereon and an outer yoke
8
formed along the outer circumference of mover
1
. Mover
1
constituted by a plastic resin substance is wound with a tracking coil
3
for executing tracking control and a focusing coil
4
for focusing control. Here, focusing coil
4
winds around the whole outer circumference of mover
1
, and tracking coil
3
winds about right and left portions thereof.
The current supply to coils
3
and
4
is conducted by four wires
6
connected with a printed circuit board
7
fixed to a frame
9
. The other ends of wires
6
are soldered to predetermined places of mover
11
to be connected to coils
3
and
4
, thereby supplying the current. That is, while wires
6
support mover
1
loaded with objective lens
2
, mover
1
is moved up and down and right and left by means of flux formed by the supplied current, thereby performing the focusing control and tracking control.
Outer yokes
8
attached with a magnet
5
onto the inside are installed onto both right and left sides of mover
1
, and inner yokes
11
within mover
1
are mounted onto the opposing sides of outer yokes
8
by interposing magnet
5
. Inner yoke
11
is furnished for forming a predetermined path of the magnetic flux from magnet
5
.
As mentioned above, the outer circumference of conventional mover
1
loaded with objective lens
2
is wound with tracking coil
3
and focusing coil
4
. Focusing coil
4
winds around the up and down portions of the outer circumference of mover
1
by a prescribed width, and tracking coil
3
partially winds about the right and left portions which face with magnet
5
. Once coils
3
and
4
are supplied with the current, in accordance with the direction of the current supplied and direction of the magnetic flux incited by magnet
5
, mover
1
is applied with a force in conformity with the Fleming's Left-hand Rule to thus carry out the tracking control and focusing control while moving up and down or right and left. At this time, the intensity of the force is decided in proportion to the relation of the magnetic flux of magnet
5
, effective length and number of turns of coils
3
and
4
and intensity of the current.
Also, the beam emitted from a light source
10
is reflected toward the objective lens side by means of a mirror
12
disposed onto the lower side of mover
1
, and the beam under the state of being focused by objective lens
2
is, prior to being reflected again, radiated onto the surface of an optical disc D which is the recording medium. An optical signal reflected in this way is to be reproduced by being converted into an electric signal via an unshown photodetector.
In accordance with the conventional construction, the beam emitted from light source
10
is to be reflected toward the objective lens side by means of mirror
12
disposed onto the lower end portion of mover
1
. That is, it can be appreciated that mirror
12
is mounted to the lower portion of mover
1
for leading the beam from light source
10
to be incident to objective lens
2
without incurring any interference. Therefore, in order to inhibit the interference of mover
1
, especially focusing coil
4
, upon the beam, mirror
12
must be placed to the lower portion of mover
1
to result in a problem of increasing overall height.
In particular, since focusing coil
4
winds around the outer circumference of mover
1
, there is a certain restriction in shortening a distance between mirror
12
which reflects the beam generated from light source
10
and objective lens
2
. This significant drawback deleteriously affects the scale-down of the optical pickup device in the conventional structure in which the centers of objective lens
2
and mover
1
coincide with each other.
Another conventional optical pickup device further minimized by considering the foregoing drawbacks is illustrated in
FIGS. 2A and 2B
. In such a conventional structure, the optical pickup device can be minimized by separating respective centers C
1
and C
2
of a mover
1
′ wound with a tracking coil and a focusing coil and an objective lens
2
′. It is constructed that mover
1
′ loaded with objective lens
2
′ is spaced apart from one side of objective lens
2
′, making it possible to install mirror
12
′ for reflecting the beam from a light source
10
′ to be nearer to objective lens
2
′. More specifically, center point C
1
of objective lens
2
′ is spaced apart from center point C
2
of mover
1
′ by as long as a prescribed distance D, so that the coils winding around mover
1
′ do not incite the interference with the beam produced from light source
10
′. By doing so, mirror
12
′ can be installed by being closer to the upper portion to enable to scale-down the product.
However, in the conventional structure formed as above, when objective lens
2
′ is moved up and down as shown in
FIG. 2A
for performing the focusing control, centers C
1
and C
2
of objective lens
2
′ and mover
1
′ do not coincide with each other. For this reason, objective lens
2
′ is not moved up and down under the horizontal state but substantially conducts the circular arc motion slanted as many as a prescribed angle with respect to center point C
2
of mover
1
′. Consequently, the precise motion characteristics cannot be produced due to the aforementioned motion to have an unstable characteristic in a specific frequency band, thereby exerting a bad influence upon the record/playback of the optical pickup.
SUMMARY OF THE INVENTION
The present invention is devised to solve the above-enumerated problems. Therefore, it is an object of the present invention to provide an optical pickup device capable of being slimmed while involving further precise control characteristic.
To achieve the above object of the present invention, an objective lens driving apparatus according to the present invention includes a mover having a focusing coil winding part formed with a prescribed inclination with respect to a horizontal plane, and a beam passing part formed in the lower portion of the focusing coil winding part for allowing beam from a light source to pass therethrough by using the inclination. Also included as part is an objective lens loaded on the upper portion of the mover while having a center substantially coinciding with that of the mover.
Preferably, a sub-magnet for forming a magnetic flux is further formed to the inside of a focusing coil mounted to the focusing coil winding part to induce sufficient generation of the magnetic flux, making it possible to precisely perform the focusing control and tracking control.
REFERENCES:
patent: 5687032 (1997-11-01), Takeshita et al.
patent: 5706270 (1998-01-01), Iizuk et al.
patent: 5724337 (1998-03-01), Kawano et al.
patent: 5870373 (1999-02-01), Choi et al.
patent: 5886978 (1999-03-01), Matsui
patent: 6
Dinh Dung C.
Kupstas Ted
LG Electronics Inc.
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