Optical: systems and elements – Lens – With support
Reexamination Certificate
2002-09-20
2004-07-27
Dang, Hung Xuan (Department: 2873)
Optical: systems and elements
Lens
With support
C359S814000, C369S044140, C369S044150
Reexamination Certificate
active
06768601
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a unit for controlling lens position in an optical pick-up device, and particularly, to a position control unit for lens of an optical pick-up device which is able to simplify the fabrication process and reduce the size and weight thereof by patterning a magnetic driving coil for focusing, tracking, and radial tilt driving of the lens on a printed circuit board (PCB).
2. Description of the Background Art
An optical pickup records and reproduces information such as video or audio data onto/from recording media, e.g., discs (or disks). A disc has a structure such that an information-recording surface is formed on a substrate.
Generally, an optical pickup device is installed on a CD player, etc. to radiate a laser light toward a recording media and to reproduce information recorded on the recording media by receiving light reflected from the recording media. And the optical pickup device comprises a hologram device for irradiating the light toward the recording media and changing the reflected light into an electric signal, a lens for concentrating the laser light irradiated from the hologram device on a disc, and a lens control unit for controlling location of the lens in order to compensate an error in case that an error is generated in the focus of laser light concentrated on the disc.
FIG. 1
is a perspective view showing a lens location control unit in an optical pickup device according to the conventional art, and
FIG. 2
is a cross-sectional view showing a lens position control unit in the optical pickup device according to the conventional art.
In the lens position control unit in the conventional optical pickup device, a lens holder
106
on which a lens
104
is fixed is disposed on an upper surface of a suspended yoke plate
102
, and suspension wires
108
are connected between the yoke plate
102
and the lens holder
106
to support the suspension of the lens holder
106
.
The lens holder
106
includes a lens
104
fixed on a center part thereof, a focusing coil
110
for focusing/driving the lens holder
106
wound on an outer side thereof in a circumferential direction, and tracking coils
112
having (rough square shapes) for tracking/driving the lens holder
106
attached on front and rear surfaces thereof.
In addition, coil PCBs
114
, to which the focusing coil
110
and the tracking coil
112
are electrically connected, are disposed on left and right side surfaces of the lens holder
106
, and a plurality of suspension wires
108
are attached to the coil PCBs
114
. Herein, two suspension wires
108
are respectively connected to each of the coil PCBs
114
to transmit a signal of a servo system to the focusing coil
110
and to the tracking coil
112
, to support the lens holder
106
elastically, and to attenuate the shock from outer side from being transmitted to the lens holder
106
.
Inner yoke
116
and an outer yoke
118
are disposed on front and rear side surfaces of the yoke plate
102
and facing each other with a predetermined interval therebetween. In addition, magnet
120
is attached to the outer yoke
118
, and the focusing coil
110
, and the tracking coil
112
are positioned between the inner yoke
116
and the outer yoke
118
.
In addition, a yoke
124
for fixing a suspension PCB
122
which is connected to the suspension wire
108
is disposed on one side of the yoke plate
102
in a vertical direction, and a gel holder
128
in which damping gel
126
(having a high viscosity) is injected, is installed on the yoke
124
in order to attenuate vibrations of the suspension wires
108
.
The suspension PCB
122
is connected to the PCB (not shown) of the main body through a flexible PCB or through a cable.
That is, the lens holder
106
having the lens
104
is lifted while maintaining a predetermined interval with the magnet
120
(which is attached to the outer yoke
118
) by the elastic force of the suspension wires
108
.
Operation of the lens position control unit in the conventional optical pickup device is described as follows:
When electric power is applied to the focusing coil
108
through the suspension wires
108
during the focusing/driving of the lens, the lens holder
106
is moved in a focusing direction, that is, in up-and-down direction to control the focus of a beam on an information-recording surface of the disc by an interaction between the focusing coil
110
and the flux generated on by the magnets
120
. In addition, when electric power is applied to the tracking coil
112
through the suspension wires
108
during the tracking/driving of the lens, the lens holder
106
is moved in the tracking direction, that is, in left-and-right directions to control tracking of the beam on an information-recording surface of the disc by an interaction between the tracking coil
112
and flux generated by the magnet
120
.
The conventional optical pickup device is able to reproduce only a particular kind of disc, and therefore, the need for an optical pickup device for a complex disc drive which is able to reproduce a disc for DVD and to record and reproduce a disc for CD-RW are developing.
In the optical pickup device of the combo type disc drive, a light source for DVD (650 nm wavelength) and a light source for CD-RW (780 nm wavelength) are used together using one lens.
A lens position control unit in the optical pickup device for the complex disc drive requires a focusing coil for focusing/driving of the lens, a tracking coil for tracking/driving of the lens, and a tilt coil for radial tilt driving of the lens.
That is, the lens position control unit according to the conventional art requires an additional tilt coil for radial tilt driving on the lens holder, and therefore, the size and weight of the optical pickup device is increased and fabrication processes thereof are complex.
Also, respective coils are formed by winding wire of a copper material, and the weight thereof is about one third of the entire weight of the lens position control unit. Therefore, the amount of electric current which is applied to respective coils is increased in order to control the position of the lens control unit, and a responding function is reduced.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a lens position control unit for an optical pickup device which is able to reduce the size of entire device, to reduce the weight of the device, and to simplify the fabrication process by patterning coils for focusing, tracking, and radial tilt driving of a lens on a printed circuit board (PCB).
To achieve the object of the present invention, as embodied and broadly described herein, there is provided a lens position control unit for an optical pickup device according to the present invention comprising: a lens holder, on which a lens is fixed, disposed on an upper part of a suspended yoke plate; suspension wires for supporting the suspension of the lens holder and applying electric power; coil PCBs, on which coils for focusing, tracking, and radial tilt driving of the lens holder are patterned, attached on front and rear parts of the lens holder respectively; and magnets positioned apart from the coil PCBs at a predetermined gap for driving the lens by an interaction with the coil PCBs.
The lens holder in the lens position control unit includes a lens on a center part thereof, mounting members to which the suspension wires are fixed on both side surfaces thereof, and a PCB for connecting electric power between the suspension wires and the coil PCB electrically attached thereto.
The PCBs for connecting electric power in the lens position control unit are attached to left and right side surfaces of the lens holder, and have suspension wires connected thereto respectively and electric power connecting patterns which are connected to the front and rear coil PCBs electrically.
Three suspension wires in the lens position control unit are connected to both PCBs for connecting electric power respectively.
The coil PCB of the lens pos
Birch & Stewart Kolasch & Birch, LLP
Dang Hung Xuan
LG Electronics Inc.
Martinez Joseph
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