Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2002-11-13
2004-08-10
Letscher, George J. (Department: 2652)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S244100
Reexamination Certificate
active
06775207
ABSTRACT:
This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2002-148914 filed in Japan on May 23, 2002, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for driving optical system for writing or reading information to and from an optical recording medium such as DVD. More particularly, it relates to a supporting mechanism and a driving mechanism for the optical system.
2. Description of the Background Art
A well-known device for driving optical system is introduced in Japanese Patent Application Laid-Open No. 2001-297460.
FIG. 17
is a perspective view illustrating a background-art device for driving optical system disclosed therein. The device given in
FIG. 17
is a driving device for optical system in which an objective lens
101
is controlled by moving coil system. The objective lens
101
is fixed to a lens holder
102
. Provided on the side surfaces of the lens holder
102
are six strip metal plates
103
a
through
103
c
, and
103
d
through
103
f
. Print coils
104
a
and
104
b
are fixed to other side surfaces of the lens holder
102
. A base member
105
has a suspension holder
106
for supporting the lens holder
102
, and permanent magnets
107
a
through
107
d
for controlling the lens holder
102
. The strip metal plates
103
a
through
103
c
and
103
d
through
103
f
are connected to the suspension holder
106
by suspension wires (linear elastic bodies)
108
a
through
108
c
and
108
d
through
108
f
, respectively, to support the lens holder
102
on the base
105
member. The print coil
104
a
is interposed between the permanent magnets
107
a
and
107
b
, and the print coil
104
b
is interposed between the permanent magnets
107
c
and
107
d.
Next, the operations of the background-art device will be discussed. When a current is supplied to focusing coils embedded in the print coils
104
a
and
104
b
(not shown) so as to generate electromagnetic forces to act on the coils in the same direction, the lens holder
102
is displaced in the direction Fo of an optical axis (hereinafter alternatively referred to as focusing direction). Further, when a current is supplied to tracking coils embedded in the print coils
104
a
and
104
b
(not shown) so as to generate electromagnetic forces to act on the coils in the same direction, the lens holder
102
is displaced in a tracking direction Tk that is a radial direction of an optical recording medium. Still further, when a current is supplied to the focusing coils (not shown) so as to generate electromagnetic forces to act on the coils with the opposite directions, rotation moment about the tracking direction Tk as an axis thereof is applied to the lens holder
102
. As a result, the lens holder
102
is rotated in a tilting direction Ti.
FIG. 18
is a sectional view illustrating how the lens holder is rotated in the tilting direction Ti. If the electromagnetic forces are generated to act on the focusing coils (not shown) in the opposite directions, the strip metal plates
103
a
and
103
c
are displaced and distorted towards the opposite directions by the same amount. As a result, a center of the strip metal plate
103
b
will be a center O of rotation in the tilting direction Ti, thus rotating the lens holder
102
to an angle &thgr; and displacing the same in the tilting direction Ti. Triaxial drive, namely, drive in the focusing direction Fo, tracking direction Tk, and in the tilting direction Ti, is thereby allowed.
For realizing triaxial drive, the background-art device requires two electric wires for supplying current to the focusing coil in the print coil
104
a
, two electric wires for supplying current to the focusing coil in the print coil
104
b
, and two electric wires for supplying current to the tracking coils in the print coils
104
a
and
104
b
, respectively. Namely, a total of six electric wires are required. For this reason, the six suspension wires
108
a
through
108
f
for supporting the lens holder
102
are also used as electric wires for current supply in the background-art device.
In the background-art device for driving optical system, however, the suspension wires
108
a
through
108
f
should contact the strip metal plates
103
a
through
103
f
on the side of the lens holder
102
. Therefore, the background-art device necessarily requires six strip metal plates, leading to the increase in number of parts. As a result, the problems involving rise in cost of the parts and increase in number of assembly steps have been unavoidable. In the background-art device, further, the suspension wires
108
a
through
108
f
and the strip metal plates
103
a
through
103
f
should be respectively connected. Therefore, variations of the parts may occur in the assembled condition, resulting in unevenness in performance of the devices.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a device for driving optical system only requiring at least six suspension wires (linear elastic bodies) for supporting a lens holder while allowing triaxial drive, namely, drive in a focusing direction, in a tracking direction, and in a tilting direction.
The device for driving optical system includes an optical system, a holder, a support member, a support system, a focusing drive system, a tracking drive system, and a tilting drive system. The optical system focuses light on an optical recording medium and irradiating the optical recording medium with focused light. The holder holds the optical system. The support member supports the holder. The support system includes at least six linear elastic bodies having the same length. The linear elastic bodies respectively have one ends fixed to the support member and arranged thereon approximately in a circle, and other ends fixed to the holder and arranged thereon approximately in a circle, to support the holder on the support member. The focusing drive system drives the holder in a direction of an optical axis of the optical system. The tracking drive system drives the holder in a radial direction of the optical recording medium. The tilting drive system drives the holder in a direction in which rotation moment generates about an axis. This axis is perpendicular to the direction of the optical axis and to the radial direction of the optical recording medium.
One ends of the at least six linear elastic bodies are fixed to the support member and arranged approximately in a circle thereon, and other ends of the six linear elastic bodies are fixed to the holder and arranged approximately in a circle thereon. The holder is thereby supported on the support member. Therefore, while allowing triaxial drive, cost reduction of parts is realized and the number of assembly steps is reduced. Further, variations of the parts can be reduced in the assembled condition, thus reducing the degree of unevenness in performance of the devices.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4794580 (1988-12-01), Ikedo et al.
patent: RE33548 (1991-03-01), Kime
patent: 5699340 (1997-12-01), Lee et al.
patent: 6342978 (2002-01-01), Nishikawa et al.
patent: 2001-297460 (2001-10-01), None
patent: 2001-319349 (2001-11-01), None
Takeshita Nobuo
Yabe Mitoru
Birch Stewart Kolasch & Birch, LLP.
Letscher George J.
Mitsubishi Denki & Kabushiki Kaisha
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