Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specified detail of transducer assembly support structure
Reexamination Certificate
2000-04-26
2002-09-17
Miller, Brian E. (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specified detail of transducer assembly support structure
C359S819000
Reexamination Certificate
active
06452895
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an objective lens driving device of an optical disk drive apparatus capable of optically reading information by projecting an optical spot onto a recording medium provided on an optical disk.
In a conventional objective lens driving device of a shaft sliding and rotating type, a lens holder for holding an objective lens, having a shaft receiving section at a position close to the center, is rotated and slid with respect to a support shaft fixed to an actuator base, and the support shaft is made of stainless steel and coated with resin of fluorine, and the shaft receiving section is made of aluminum. In this case, clearance is formed between the support shaft and the shaft receiving section. Therefore, the lens holder integrated with the shaft receiving section is tilted in an arbitrary direction according to the clearance between the support shaft and the shaft receiving section. As a result, aberration is caused in the laser beams which are incident on the objective lens and condensed onto the disk, which has a bad influence on the optical characteristic of the optical disk drive apparatus. If the clearance is reduced so as to decrease the tilting angle, it becomes difficult for the lens holder to move smoothly. If the support shaft and the shaft receiving section are extended without reducing the clearance, it becomes difficult to decrease the thickness of the objective lens driving device.
In order to solve the above problems, there is disclosed an objective lens driving device of a sliding and rotating type in JP-A-11-25484. Referring to
FIG. 2
, the objective lens driving device will be explained below. In
FIG. 2
, reference numeral
1
is an objective lens for irradiating laser beams on an optical disk, reference numeral
2
is a lens holder for holding the objective lens
1
, having a shaft receiving section
2
a
at a position close to the center, reference numeral
3
is a focus coil for driving the lens holder
2
in the focusing direction, reference numeral
4
is a tracking coil for driving the lens holder
2
in the tracking direction, reference numeral
5
is a feeder wire for feeding a drive current to the tracking coil
4
, reference numeral
6
is a magnetic yoke for forming a magnetic circuit, reference numeral
7
is a magnet, reference numeral
8
is a support shaft for supporting the lens holder
2
slidably and pivotally, reference numeral
9
is an actuator base, and reference numeral
10
is an auxiliary magnet arranged close to the shaft receiving section
2
a.
The objective lens
1
, focus coil
3
and tracking coil
4
are fixed to the lens holder
2
, and these components compose a movable section.
The support shaft
8
is fixed onto the actuator base
9
. The support shaft
8
supports the movable section by the shaft receiving section
2
a
arranged in the lens holder
2
in such a manner that the movable section can be rotated and slid with respect to the support shaft
8
. The magnetic yoke
6
and magnet
7
compose a magnetic circuit. The movable section is driven in the rotating and the sliding direction with respect to the support shaft
8
by the electromagnetic force generated by the electric currents, which are respectively supplied to the focus coil
3
and the tracking coil
4
, and the magnetic circuit. The auxiliary magnet
10
is fixed to the lens holder
2
and generates a magnetic attraction force with respect to the support shaft
8
.
Referring to
FIG. 3
, operation of the above objective lens driving device will be explained as follows. In
FIG. 3
, reference numeral
11
is an optical disk, reference mark &thgr; is a tilt angle formed between the lens holder
2
and the support shaft
8
, and reference mark F is a magnetic attraction force of the auxiliary magnet
10
with respect to the support shaft
8
. As shown in
FIG. 3
, magnetic attraction force F generated by the auxiliary magnet
10
, which is fixed to the lens holder
2
, with respect to the support shaft
8
acts in such a manner that the shaft receiving section
2
a
of the lens holder
2
comes into linear contact with the support shaft
8
. Accordingly, the lens holder
2
rotates round and slides on the support shaft
8
while the shaft receiving section
2
a
of the lens holder
2
is coming into linear contact with the support shaft
8
. Therefore, tilt angle &thgr; created by the clearance formed between the shaft receiving section
2
a
and the support shaft
8
can be kept constant at all times. Accordingly, even if the clearance is formed between the support shaft
8
and the lens holder
2
, the posture of the objective lens
1
can be kept constant at all times.
However, according to the prior art described above, the following problems may be encountered. Since the auxiliary magnet
10
is fixed to the lens holder
2
so that a relative angle formed between the support shaft
8
and the lens holder
2
can be kept by giving a pushing force to push the lens holder
2
in the direction perpendicular to the axial direction of the support shaft
8
, it takes time and labor to assemble the device. Further, since the support shaft
8
and the shaft receiving section
2
a
are strongly contacted with each other by the pushing force, although the tilt angle can be decreased, there is a possibility that the lens holder
2
can not be moved smoothly.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above problems of the prior art.
The present invention provides an objective lens driving device of an optical disk drive apparatus of a shaft sliding and rotating type in which a lens holder for holding an objective lens is rotated and slid, in that ceramics is applied to one of a support shaft and shaft receiving section.
According to the above structure, the coefficient of friction of one of the support shaft and the shaft receiving section or the coefficients of friction of both the support shaft and the shaft receiving section can be reduced and further the accuracy of machining can be enhanced. Therefore, the clearance formed between the support shaft and the shaft receiving section can be reduced.
REFERENCES:
patent: 5724337 (1998-03-01), Kawano et al.
patent: 5877904 (1999-03-01), Kawano et al.
patent: 6084834 (2000-07-01), Kawano et al.
patent: 62-245537 (1987-10-01), None
patent: 62-262236 (1987-11-01), None
patent: 62-262237 (1987-11-01), None
patent: 2713564 (1997-10-01), None
patent: 11-25484 (1999-01-01), None
Miller Brian E.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
TDK Corporation
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