OPTICAL ELEMENT FEEDING DEVICE AND OPTICAL PICKUP UNIT USING THE SAME

Abstract

In an optical element feeding device and an optical pickup unit using the same, in order to make the device compact and light and achieve a stable operation, the device has a main shaft and a sub shaft supporting a movable frame in which an optical element is arranged in such a manner as to be movable in a direction of an optical axis, a stepping motor, a lead screw rotating on the basis of a rotation of the stepping motor, a resin nut engaging with the lead screw and being movable in the direction of the optical axis on the basis of the rotation of the lead screw, and a spring pressing the movable frame in the direction of the optical axis so as to bring the movable frame into contact with the nut, and a cushioning material is provided between the nut and the movable frame so as to connect the nut and the movable frame.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWING

FIG. 1 is a view for explaining a structure of a lens feeding device in accordance with an embodiment of the present invention;

FIG. 2 is an enlarged explanatory view of the lens feeding device in FIG. 1;

FIG. 3 is a schematic block diagram showing a layout of an optical element in an optical pickup unit in accordance with an embodiment of the present invention;

FIGS. 4A, 4B and 4C are explanatory views of a shape of a nut portion in accordance with an embodiment of the present invention;

FIGS. 5A and 5B are explanatory views of a cushioning material provided in the nut portion in accordance with an embodiment of the present invention;

FIG. 6 is an explanatory view of a weight provided in the nut portion in accordance with the embodiment of the present invention; and

FIG. 7 is an explanatory block diagram of an optical disc device using the lens feeding device in accordance with the present invention.

Claims

1. An optical element feeding device for moving an optical element in a direction of its optical axis, comprising: a support means for supporting a movable member in which the optical element is arranged in such a manner as to be movable in the direction of the optical axis;a stepping motor;a screw arranged in parallel to the direction of the optical axis and rotating on the basis of a rotation of a rotating shaft of the stepping motor;a resin nut engaging with the screw, said resin nut being provided with a rotation preventing portion and being movable in the direction of the optical axis on the basis of the rotation of the screw; anda pressing member pressing the movable member in the direction of the optical axis so as to bring the movable member into contact with the nut,wherein said nut is coupled to said movable member by a cushioning material.

2. The optical element feeding device as claimed in claim 1, wherein said screw is directly connected onto the rotating shaft of said stepping motor.

3. The optical element feeding device as claimed in claim 1, wherein said cushioning material couples a part of said nut and a part of said movable member.

4. The optical element feeding device as claimed in claim 3, wherein a concave portion or a convex portion for keeping said cushioning material is formed in at least one of said movable member and said nut.

5. The optical element feeding device as claimed in claim 1, wherein a metal is formed around said resin nut except said rotation preventing portion.

6. An optical pickup unit comprising: the optical element feeding device as claimed in claim 1;a laser light source;a collimator lens changing a laser beam radiated from said laser light source to a parallel light;a collecting lens for collecting said laser beam on an optical disc; anda light detector detecting a return light from said optical disc.

7. An optical element feeding device for moving an optical element in a direction of its optical axis, comprising: a support means for supporting a movable member in which the optical element is arranged in such a manner as to be movable in the direction of the optical axis;a stepping motor;a screw arranged in parallel to the direction of the optical axis and rotating on the basis of a rotation of a rotating shaft of the stepping motor;a resin nut engaging with the screw, said resin nut being provided with a rotation preventing portion and being movable in the direction of the optical axis on the basis of the rotation of the screw; anda pressing member pressing the movable member in the direction of the optical axis so as to bring the movable member into contact with said nut,wherein a part of said nut is formed by a metal.

8. An optical pickup unit comprising: the optical element feeding device as claimed in claim 7;a laser light source;a collimator lens changing a laser beam radiated from said laser light source to a parallel light;a collecting lens for collecting said laser beam on an optical disc; anda light detector detecting a return light from said optical disc.