Anti-shake system

1. An anti-shake system comprising:

a movable portion to which an optical element is mounted;

a support member which holds said movable portion in a manner to allow said movable portion to move freely in directions orthogonal to an optical axis; and

a drive system which drives said movable portion in said directions orthogonal to said optical axis,

wherein a natural frequency of said movable portion that originates from said movable portion and said support member is set within the range of frequencies of shaking of an apparatus equipped with said anti-shake system which is caused by hand shake.

2. The anti-shake system according to claim 1 , further comprising a closed-loop control system for driving said drive system based on a shake detection signal.

3. The anti-shake system according to claim 1 , wherein said support member comprises at least one resilient member which holds said movable portion in said manner to allow said movable portion to move freely in said directions orthogonal to said optical axis, and

wherein said drive system drives said movable portion in a direction of resilient stress of said resilient member.

4. The anti-shake system according to claim 1 , wherein said support member comprises at least one resilient member which holds said movable portion at an initial position while allowing said movable portion to move freely in said directions orthogonal to said optical axis,

wherein said optical element includes an image pickup device;

wherein at least one of an elastically deformable signal line and an elastically deformable electric supply line is connected to said image pickup device from outside of said movable portion, and

wherein said natural frequency of said movable portion originates from said movable portion, said support member and said one of said elastically deformable signal line and said elastically deformable electric supply line.

5. The anti-shake system according to claim 1 , wherein said natural frequency of said movable portion is set by adjusting a spring constant of said resilient member.

6. The anti-shake system according to claim 1 , wherein said natural frequency of said movable portion is set to below 15 Hz.

7. The anti-shake system according to claim 1 , wherein said natural frequency of said movable portion is set within a range of frequencies from 3 to 9 Hz.

8. The anti-shake system according to claim 1 , wherein said support member comprises:

a pair of X-axis direction leaf springs and a pair of Y-axis direction leaf springs which extend in a specific X-axis direction and a Y-axis direction orthogonal to said X-axis direction in a free state, respectively.

9. The anti-shake system according to claim 1 , wherein said drive system comprises:

an X-axis direction planar drive coil and a Y-axis direction planar drive coil which are mounted to a coil substrate to be respectively positioned in magnetic fields of two stationary magnets.

10. The anti-shake system according to claim 1 , wherein said apparatus that is equipped with said anti-shake system comprises a camera.

11. The anti-shake system according to claim 9 , wherein said optical element is mounted on said coil substrate, and

wherein said optical element comprises one of a correction optical system and an image pickup device.

12. An anti-shake system of a camera, comprising:

a movable portion which supports an optical element of a photographing optical system of said camera, said movable portion being supported to be freely movable in directions orthogonal to an optical axis of said photographing optical system; and

a drive system which drives said movable portion in said directions orthogonal to said optical axis to counteract effects of camera shake that is caused by hand shake, wherein a natural frequency of said movable portion is set within a range of frequencies of said camera shake.

13. The anti-shake system of a camera according to claim 12 , wherein said optical element comprises one of an image pickup device and a lens element.