Lens driving device and camera module comprising same
A lens driving device according to an embodiment comprises: a movable unit on which at least one lens is mounted; a first coil and a driving magnet which face and interact with each other such that the movable unit is moved in the optical axis direction of the lens; a position sensor for sensing the position of the movable unit in the optical axis direction or a driver comprising the position sensor; and a positively magnetized magnet arranged to face the position sensor or the driver, wherein the positively magnetized magnet comprises a first side surface, which faces the position sensor and has a first polarity, and a second side surface, which faces the position sensor, which is arranged to be spaced from the first side surface in a direction parallel with the optical axis direction or arranged to abut the first side surface, and which has a second polarity that is the opposite of the first polarity of the first side surface, and the length of the first side surface in the optical axis direction may be equal to or larger than the length of the second side surface in the optical axis direction.
1. A lens driving device, comprising:
a cover member comprising:
a first lateral plate:
a second lateral plate disposed opposite to the first lateral plate;
a third lateral plate; and
a fourth lateral plate disposed opposite to the third lateral plate;
a housing member disposed in the cover member;
a bobbin disposed in the housing member;
a coil unit disposed around an outer peripheral surface of the bobbin;
first and second driving magnets facing the coil unit, wherein the first and second driving magnets are coupled to the first lateral plate and the second lateral plate of the cover member, respectively;
an upper elastic member coupled to an upper surface of the bobbin;
a lower elastic member coupled to a lower surface of the bobbin;
a sensing magnet disposed on a side wall of the bobbin, overlapped with the third lateral plate of the cover member; and
a position sensor facing the sensing magnet and being configured to sense a movement of the sensing magnet in a z-direction along an optical axis,
wherein the side wall of the bobbin is overlapped with the third lateral plate of the cover member in an x-axis direction perpendicular to the z-axis direction and perpendicular to the fourth lateral plate, and
wherein the sensing magnet is not overlapped with the coil unit and the third lateral plate of the cover member in the x-axis direction.
2. The lens driving device according to claim 1 , wherein the bobbin comprises recess on the side wall of the bobbin, and
wherein the sensing magnet is disposed in the recess of the bobbin.
3. The lens driving device according to claim 1 , wherein the lower elastic member comprises a first lower elastic member and a second lower elastic member,
wherein the first and second lower elastic members are connected to two ends of the coil unit, respectively.
4. The lens driving device according to claim 1 , wherein the sensing magnet is disposed above the coil unit in the z-axis direction.
5. The lens driving device according to claim 1 , wherein
at least a portion of the sensing magnet is disposed more inwardly toward the optical axis than is the coil unit as measured from the outer peripheral surface of the bobbin.
6. The lens driving device according to claim 1 , wherein the sensing magnet comprises a bipolar-magnetized magnet.
7. The lens driving device according to claim 1 , wherein an opening is formed at the third lateral plate of the cover member, and
wherein the sensing magnet is overlapped with the opening in the x-axis direction.
8. The lens driving device according to claim 7 , wherein the opening is a hole.
9. The lens driving device according to claim 1 , further comprising:
a circuit board coupled with the position sensor; and
a base coupled with the cover member,
wherein the circuit board comprises a plurality of terminals,
wherein the first and second driving magnets are disposed on the housing member in a y-axis direction perpendicular to each of the z-axis and x-axis directions, so as to be in parallel to each other,
wherein the circuit board is disposed at a position corresponding to a position of a side wall of at least one of the bobbin, the housing member, and the cover member in the x-axis direction, and
wherein the lower elastic member is electrically connected to the circuit board.
10. The lens driving device according to claim 2 , wherein the bobbin further comprises an additional recess disposed opposite to the recess; and
wherein a weight-balancing member is disposed in the additional recess and has a weight same as that of the sensing magnet.
11. The lens driving device according to claim 6 , wherein the bipolar-magnetized magnet comprises:
a first portion facing the position sensor and having a first polarity; and
a second portion facing the position sensor, disposed to be spaced apart from or in contact with the first portion in the z-axis direction, and having a second polarity opposite the first polarity, and
wherein a length of the first portion in the z-axis direction is equal to or greater than a length of the second portion in the z-axis direction.
12. The lens driving device according to claim 1 , wherein the first and second driving magnets are bonded and fixed to the first and second lateral plates of the cover member, respectively, and
wherein a size of the sensing magnet is smaller than that of each of the first and second driving magnets.
13. The lens driving device according to claim 1 , further comprising an inner yoke integrally formed with the cover member,
wherein the inner yoke is disposed at a position corresponding to that of a corner of the housing member, and
wherein the inner yoke comprises:
a bent portion bent downwardly from the cover member; and
a bottleneck section formed at positions adjacent to the bent portion, the bottleneck section of the inner yoke being symmetrically formed.
14. The lens driving device according to claim 3 , wherein the two ends of the coil unit are arranged on opposite sides with respect to the optical axis.
15. The lens driving device according to claim 1 , wherein the bobbin comprises a plurality of lower support protrusions protruded from the lower surface thereof,
wherein the lower elastic member comprises a plurality of through holes formed at positions corresponding to positions of the lower support protrusions, and
wherein the lower support protrusions are secured to the through holes and are arranged in a symmetrical manner with respect to the optical axis.
16. A camera module, comprising:
a cover member comprising a first lateral plate, a second lateral plate disposed opposite to the first lateral plate, a third lateral plate, and a fourth lateral plate disposed opposite to the third lateral plate;
a housing member disposed in the cover member;
a bobbin disposed in the housing member;
a lens coupled to the bobbin;
a coil unit disposed around an outer peripheral surface of the bobbin;
first and second driving magnets facing the coil unit, wherein the first and second driving magnets are coupled to the first lateral plate and the second lateral plate of the cover member, respectively;
an upper elastic member coupled to an upper surface of the bobbin;
a lower elastic member coupled to a lower surface of the bobbin;
a sensing magnet disposed on a side wall of the bobbin and overlapped with the third lateral plate of the cover member;
a position sensor facing the sensing magnet and being configured to sense a movement of the sensing magnet in a z-axis direction along an optical axis,
a first circuit board; and
an image sensor coupled to the first circuit board,
wherein the side wall of the bobbin is overlapped with the third lateral plate of the cover member in an x-axis direction perpendicular to the z-axis direction and perpendicular to the fourth lateral plate, and
wherein the sensing magnet is not overlapped with the coil unit and the third lateral plate of the cover member in the x-axis direction.
17. The camera module according to claim 16 , wherein an opening is formed at the third lateral plate of the cover member, and
wherein the sensing magnet is overlapped with the opening in the x-axis direction.
18. The camera module according to claim 17 , wherein the opening is a hole.
19. The camera module according to claim 16 , further comprising:
a second circuit board coupled with the position sensor; and
a base coupled with the cover member,
wherein the second circuit board comprises a plurality of terminals, and
wherein the lower elastic member is connected to the second circuit board.
20. A lens driving device, comprising:
a cover member comprising a first lateral plate, a second lateral plate disposed opposite to the first lateral plate, a third lateral plate, and a fourth lateral plate disposed opposite to the third lateral plate;
a housing member disposed in the cover member;
a bobbin disposed in the housing member;
a coil unit disposed around an outer peripheral surface of the bobbin;
first and second driving magnets facing the coil unit, wherein the first and second driving magnets are coupled to the first lateral plate and the second lateral plate of the cover member, respectively;
a sensing magnet disposed on a side wall of the bobbin and overlapped with the third lateral plate of the cover member;
a position sensor facing the sensing magnet and being configured to sense a movement of the sensing magnet in a z-axis direction along an optical axis, and
an opening formed at the third lateral plate of the cover member,
wherein the side wall of the bobbin is overlapped with the third lateral plate of the cover member in an x-axis direction perpendicular to the z-axis direction and perpendicular to the fourth lateral plate, and
wherein the sensing magnet is not overlapped with the coil unit and is overlapped with the opening in the x-axis direction.