Magnetic coil actuator

Details Magnetic coil actuator Magnetic coil actuator

1999-07-14

2002-12-31

Hudspeth, David (Department: 2652)

Dynamic information storage or retrieval

Dynamic mechanism subsystem

Specified detail of transducer assembly support structure

C360S265000

Reexamination Certificate

active

06501726

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a magnetic coil actuator, and particularly relates a lens tracking or focusing driving coil appliance in a CD (compact disc) or DVD (digital versatile disc) driver.
DESCRIPTION OF THE RELATED ART
It is known in the art to use a magnetic coil actuator for driving a high precision device, such as a magnetic pickup head in a hard disc driver for tracking the disc tracks, or an optical pickup head in an optical disc driver for focusing the data pits.
FIGS. 1A and 1B
illustrate a coil driving device of the prior art. It includes mainly a magnet
10
, a coil
11
and a yoke
12
. The magnetic field of the permanent magnet
10
is illustrated as circular magnetic lines in FIG.
1
B. Only a part of the coil
11
is disposed which is charged with to work with the magnetic field of the permanent magnet
10
when a controlling current is charged into the coil
11
. However, since the remaining portion of the coil
11
is not disposed aligned with the magnetic field of the magnet
10
, the utilitation efficiently of the magnet
10
to the coil
11
is rather low and wasteful.
It is especially true for today's high reading speed optical disc drivers that the need for accurate tracking and focusing operations requires higher outputs from the coil actuators. Otherwise the tracking or focusing cannot timely respond to the vibration of the disc.
This problem has been recognized by the inventors of the present invention that. The coil actuators of the prior art do not fully utilize the capacity of the coil and do not meet the requirements of high speed optical disc applications.
SUMMARY OF THE INVENTION
Accordingly, the primary object of the present invention is to improve the output of a magnetic coil actuator but not to increase the volume of the coil.
A second object of the present invention is to improve the coil actuator of a tracking dervomechanism used in an optical pickup head, and to meet the requirements of higher speed optical disc applications.
A further object of the present invention is to improve the coil actuator, of a focusing servo in an optical pickup head.
A coil actuator according to the present invention uses a flexible magnetic coil whose shape is adjusted to correspond to (i.e., be aligned with) the magnetic field of a static magnet. The coil is suitably bent to have its two diametric sections falling into the magnetic lines of a magnet, so as to maximize the utilization efficiency of the coil relative to the magnetic field. Therefore, the coil actuator maintains the original volume and the same power consumption, but provides a higher output.


REFERENCES:
patent: 4506307 (1985-03-01), Watrous
patent: 4570249 (1986-02-01), Malissin et al.
patent: 4775908 (1988-10-01), Ycas
patent: 4835643 (1989-05-01), Schulze
patent: 5247410 (1993-09-01), Ebihara et al.
patent: 5351221 (1994-09-01), Ohno
patent: 5414680 (1995-05-01), Ikegame
patent: 5524004 (1996-06-01), Van Rosmalen
patent: 5579295 (1996-11-01), Van Rosmalen

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