Lens driving apparatus and camera module including the same

1 . A lens driving apparatus, comprising:

a first frame which accommodates a lens;

a driver, connected to the first frame, and configured to generate a driving force to move the first frame in a first direction; and

a group of rolling members comprising at least one multi-layered rolling member including two or more different materials,

wherein the group of rolling members at least partially contacts the first frame,

wherein the at least one multi-layered rolling member comprises a core part and an outer part that surrounds the core part, and wherein the outer part is formed of a material that is different from a material of the core part, and

wherein the material of the core part has a lower modulus of elasticity than a modulus of elasticity of the material of the outer part.

2 . The lens driving apparatus of claim 1 , wherein the rolling members of the group of rolling members have a ball shape.

3 . The lens driving apparatus of claim 1 , wherein the core part includes a plastic material.

4 . The lens driving apparatus of claim 1 , wherein the outer part includes a ceramic material.

5 . The lens driving apparatus of claim 1 , wherein

a radius of the core part is equal to or greater than 70% of a radius of the at least one multi-layered rolling member, and equal to or less than 90% of the radius of the at least one multi-layered rolling member.

6 . The lens driving apparatus of claim 1 , further comprising:

a second frame disposed below the first frame; and

a first rolling groove disposed between the first frame and the second frame, and configured to accommodate at least a portion of the group of rolling members to guide a movement in the first direction.

7 . The lens driving apparatus of claim 6 , wherein

the first direction is an optical axis direction,

two or more rolling members of the group of rolling members are stacked in the optical axis direction, and are disposed in the first rolling groove; and

at least one of the rolling members disposed at an outermost portion of the first rolling groove is the at least one multi-layered rolling member.

8 . The lens driving apparatus of claim 7 , wherein the at least one multi-layered rolling member is disposed at the outermost portion of the first rolling groove closest to a direction on which the light is incident.

9 . The lens driving apparatus of claim 6 , wherein the driver comprises:

a first driver configured to generate a driving force to move the first frame in the first direction; and

a second driver configured to generate a driving force to move the first frame in a second direction different from the first direction.

10 . The lens driving apparatus of claim 9 , further comprising

a third frame disposed below the second frame, and

a second rolling groove disposed between the second frame and the third frame and configured to accommodate at least a portion of the group of rolling members to guide a movement in the second direction different from the first direction.

11 . The lens driving apparatus of claim 10 , wherein the first rolling groove and the second rolling groove are each configured to accommodate at least one or more of the at least one multi-layered rolling members.

12 . An electronic device comprising the lens driving apparatus of claim 1 .

13 . A camera module, comprising:

a lens;

a first frame which accommodates the lens;

a second frame disposed below the first frame;

a driver, connected to the first frame, and configured to generate a driving force to move the first frame in a first direction; and

a plurality of rolling members that is disposed between the first frame and the second frame and at least partially contacts the first frame,

wherein at least one of the plurality of rolling members is a multi-layered rolling member including two or more different materials,

wherein the at least one multi-layered rolling member comprises a core part and an outer part that surrounds the core part, and wherein the outer part is formed of a material that is different from a material of the core part, and

wherein the material of the core part has a lower modulus of elasticity than a modulus of elasticity of the material of the outer part.

14 . The camera module of claim 13 , wherein

the core part includes a plastic material, and

the outer part includes a ceramic material.

15 . The camera module of claim 13 , wherein

a radius of the core part is equal to or greater than 70% of a radius of the multi-layered rolling member, and equal to or less than 90% of the radius of the multi-layered rolling member.

16 . An electronic device, comprising the camera module of claim 13 .