Optical pick-up device of disk player

Details Optical pick-up device of disk player Optical pick-up device of disk player

2001-07-06

2003-10-14

Edun, Muhammad (Department: 2655)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S044150, C369S112230, C359S813000

Reexamination Certificate

active

06633519

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slim type optical pick-up device for recording and/or reproducing information into and from an optical disk.
2. Description of the Background Art
In general, an optical pick-up device records and/or reproduces information by transmitting and receiving a light to and from the optical disk. According to an notebook computer or an portable disk player is more and more slim, the optical pick-up device for an notebook computer or an portable disk player is needed more compact
FIG. 1
is a schematic view showing the construction of an optical pick-up device in accordance with a conventional art.
As shown in
FIG. 1
, in the conventional optical pick-up device, a frame
20
is installed at a rear side of a yoke plate
10
, and a printed circuit board (PCB)
30
is mounted at a rear side of the frame
20
and connected to an pick-up driving circuit through a flexible print circuit (FPC)
33
.
An outer yoke
12
and an inner yoke
13
stand at a front side of the yoke plate
10
, and permanent magnets
17
and
18
are fixed in a facing manner between the two yokes
12
and
13
.
A holder
40
is positioned at a front side of the yoke plate
10
, which is supported by four suspension wires
35
connected to the PCB
30
.
The holder
40
includes an objective lens
41
for focussing light radiated from a light source on a recording layer of the optical disk, and a magnetic driving coils
45
for varying a position of the holder
40
horizontally and vertically according to the mutual interaction with the permanent magnets
17
and
18
.
The frame
20
is provided with holes
21
, through which the suspension wires
35
pass. The suspension wires
35
are made of a conductive material so that a signal outputted from the PCB
30
can be applied to the magnetic driving coils
45
.
In the optical pick-up device, in a state that the holder
40
is supported by the suspension wires
35
, as it moves vertically and horizontally according to a mutual interaction between the magnetic driving coils
45
and the permanent magnets
17
and
18
, the position of the objective lens
41
can be varied, and accordingly, focussing and tracking operations are performed.
With reference to
FIGS. 2 through 4
, a coupling structure between the yoke plate
10
, the frame
20
and the PCB
30
will now be described.
FIGS. 2 and 3
are a side view and a plan view showing the coupling structure of the yoke plate, the frame and the PCB, and
FIG. 4
is a development view of the yoke plate.
With reference to
FIG. 4
, as for the yoke plate
10
, an outer yoke
12
and an inner yoke
13
are formed bent upwardly at the front side of a bottom portion
11
, side portions
14
are formed bent upwardly at both sides of the yoke plate
10
, and a fixing portion
15
is formed bent upwardly at the rear side.
A fixing portion
15
includes a hole
15
a
at the central portion to engage a screw
31
therethrough.
With reference to
FIGS. 2 and 3
, in the yoke plate
10
, the permanent magnets
17
and
18
are fixed in a manner of attaching to the outer yoke
12
and the inner yoke
13
, and the frame
20
and the PCB
30
are threaded by the screw
31
at the rear side of the fixing portion
15
.
However, the conventional optical pick-up device as described above has the following problem. That is, as shown in
FIGS. 2 and 4
, since the height and the width of the inner yoke
13
are formed shorter and smaller than those of the outer yoke
12
, the inner yoke
13
has a relatively restricted coercive force of the permanent magnet
18
, at which an operation characteristic of the optical pick-up device is degraded.
The reason why the inner yoke
13
is formed smaller than the outer yoke
12
is that, with reference to
FIG. 4
, the hole
15
a
is formed in the fixing portion
15
of the yoke plate
10
, through which the PCB
30
and the frame
20
are threaded by the screw
31
, and in this respect, in order to obtain a sufficient supporting force against the PCB
30
and the frame
20
as well as to provide the hole
15
a
at the fixing portion
15
, there is a limitation to reduce the area of the fixing portion
15
. Otherwise, if the optical pick-up device is desired to be designed compact under the condition that the fixing portion
15
is enlarged, the size of the inner yoke
13
is relatively reduced.
Consequently, in order for the fixing portion
15
to form the hole
15
a
for threading as well as obtain a sufficient supporting area, the inner yoke
13
is inevitably limited in its size.
If the fixing portion
15
is designed to have a sufficient supporting area while increasing the size of the inner yoke
13
, the overall yoke plate
10
is enlarged, causing a problem that the optical pick-up device wouldn't be designed compact.
The above-described conventional optical pick-up device has another problem. The PCB
30
and the frame
20
are fixed by being threaded by one screw
31
at the fixing portion
15
of the yoke plate
10
, so that if the engaging force of the screw
31
is weakened or due to the typically flexible characteristic of the PCB
30
, as shown in
FIG. 5
, when the holder
40
is moved vertically or horizontally, the PCB
30
and the frame
20
are simultaneously moved, causing an abnormal movement of an objective lens
41
, resulting in failure of a normal focussing and tracking operation.
In other words, when the holder
40
is moved according to a mutual interaction between the magnetic driving coil
45
and the permanent magnets
17
and
18
, if the PCB
30
connected to the suspension wires
35
are inclined vertically or horizontally, the central axis of the objective lens
41
would deviate from the center position as shown in FIG.
5
. And at this time, a normal focussing and tracking operation do not made, so that the performance of the optical pick-up device is degraded.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an optical pick-up device which is capable of being designed more compactness while heightening a coercive force of a permanent magnet and capable of improving an operation characteristic and performance for an optical pick-up by fixing a PCB and a frame at a yoke plate without being shaken.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an optical pick-up device including: a yoke plate having yokes formed at a front side where a magnetic body and a magnetic driving unit are positioned to drive an objective lens; a frame fixed to the yoke plate in such a manner that a portion of the rear side of the yoke plate is inserted thereinto; and a PCB with at least two portions fixed to the frame, for applying a drive signal to the magnetic driving unit.
In the optical pick-up device of the present invention, the yoke plate includes: an outer yoke bent in the orthogonal direction to a bottom portion at the front side; an inner yoke cut at the middle portion of the yoke plate and bent in the same direction of the outer yoke; and an insertion portion bent in the orthogonal direction to the bottom portion so as for the frame to be fixed thereto.
In the optical pick-up device of the present invention, the outer yoke and the inner yoke are formed having the same size, and the insertion portion is formed in a ‘U’ shape.
In the optical pick-up device of the present invention, as for the inner yoke, its upper portion is cut at the inner portion of the insertion portion beyond the line where the insertion portion is bent from the bottom portion.
In the optical pick-up device of the present invention, the objective lens and the magnetic driving unit are installed at a holder, and the holder is supported by a plurality of suspension wires connected to the PCB.
In the optical pick-up device of the present invention, the frame includes holes through which the suspension wires pass, and the holes are formed with its upper portion opened so that the sus

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