Electromagnetic actuators for digital cameras

Patent metadata

Field	Value
Publication number	US-2016209618-A1
Application number	US-201414373490-A
Country	US
Kind code	A1
Filing date	Jul 3, 2014
Priority date	Nov 6, 2013
Publication date	Jul 21, 2016
Grant date	—

Abstract

Electro-magnetic actuators used to provide a displacement of an optical element such as a lens carrier comprise at least one ferromagnetic frame associated with a large air gap and at least one ferromagnetic member parallel to and separated from an elongated section of a frame by a small air gap. Actuation causes a magnetic circuit that appears in the at least one frame, the at least one member and small air gaps and by-passes or bridges the large air gap. In some embodiments, the resultant magnetic force moves the at least one member and leads to the displacement of an optical element attached thereto. In some embodiments, at least one frame and at least one member are arranged to provide a center hole and are dimensioned to enable insertion of a lens carrier in the hole. In some embodiments, the displacement is for auto-focus. In other embodiments, the displacement is for optical image stabilization.

First claim

1 . An electro-magnetic actuator used to provide a movement of an optical element, comprising:
a) a ferromagnetic first frame that includes a core surrounded partially by a first conductive coil, a first arm and a second arm, each arm having an operative surface and an end surface, the first and second arms separated therebetween by a first large air gap; and b) a ferromagnetic first member having a respective operative surface and facing the first arm, the first member and the first arm disposed such that a first small air gap and an overlap are formed between their respective operative surfaces, wherein the first small air gap is smaller than the first large air gap, wherein the first member and the first frame undergo a relative movement therebetween when a magnetic force is generated by current in the coil and wherein the movement is convertible into a displacement of the optical element from a first position to a second position.

2 . The actuator of claim 1 , wherein the optical element is coupled mechanically to the first member.

3 . The actuator of claim 1 , wherein the frame has a G-shape and wherein the first member has two operative surfaces and is nested between the two arms, each first member operative surface facing a respective operative surface of an arm across a respective small air gap.

4 . The actuator of claim 1 , further comprising:
c) a ferromagnetic second member rigidly coupled to the first member, the second member having a respective operative surface and facing the second arm, the second member and the second arm disposed such that a second small air gap and an overlap are formed between their respective operative surfaces, wherein the second small air gap is smaller than the first large air gap.

5 . The actuator of claim 4 , wherein the first and second members form a ferromagnetic ring nested inside the first frame.

6 . The actuator of claim 4 , further comprising:
d) a ferromagnetic second frame that includes a second frame core surrounded partially by a second conductive coil, the second frame having first and second frame arms separated therebetween by a second large air gap, each second frame arm having at least one operative surface and an end surface, wherein the first member faces a first pair of arms formed by a first frame arm and a second frame arm, wherein the second member faces a second pair of arms formed by a first frame arm and a second frame arm, each of the first and second members and their respective facing pairs arms disposed such that a small air gap and an overlap are formed between their respective operative surfaces, wherein each small air gap is smaller than either the first or second air gaps, and wherein each member and its respective pair of arms undergo a relative movement therebetween when a magnetic force is generated by current in each of the first and second coils, the movement convertible into a displacement of the optical element from a first position to a second position.

7 . The actuator of claim 6 , wherein the first and second frames are dimensioned to provide an internal open space that can accommodate the optical element.

8 . The actuator of claim 6 , wherein the first and second frames and the first and second members are curved.

9 . The actuator of claim 6 , wherein the arms of each frame are substantially perpendicular to each other, wherein the first and second large air gaps are formed between end surfaces of a first frame arm and a second frame arm, and wherein the first and second members are L-shaped.

10 . The actuator of claim 6 , wherein the first and second frame arms are coplanar.

11 . The actuator of claim 6 , wherein the first and second cores and coils are coplanar, and wherein the first frame arms and the second frame arms form an angle θ with a plane of the respective first and second cores.

12 . The actuator of claim 11 , wherein angle θ is between 0 and 5°.

13 . The actuator of claim 1 , wherein the operative surfaces facing each other across the small air gaps are parallel to each other and to a direction of the movement.

14 . The actuator of claim 1 , wherein the operative surfaces facing each other across the small air gaps are parallel to each other and form an angle φ with a direction of the movement.

15 . The actuator of claim 1 , wherein the operative surfaces facing each other across the small air gaps are non-parallel and form an angle φ.

16 . The actuator of claim 14 , wherein angle φ is between 0 and 5°.

17 . The actuator of claim 15 , wherein angle φ is between 0 and 5°.

18 . The actuator of claim 1 , wherein the displacement ranges between 0 and approximately 1000 μm.

19 . The actuator of claim 1 , wherein the optical element is a lens assembly.

20 . (canceled)

21 . (canceled)

22 . The actuator of claim 1 , wherein the actuator is included in a mobile device that includes a digital camera.

Assignees

• Corephotonics Ltd

Inventors

• Avivi Gal
• Goldenberg Ephraim
• Nasser Jamil
• Bachar Gil
• Shabtay Gal

Classifications

• G02B7/04 Primary

  with mechanism for focusing or varying magnification · CPC title

• G11B7/0925

  Electromechanical actuators for lens positioning (G11B7/0857 takes precedence) · CPC title

• G11B7/093

  for focusing and tracking (G11B7/0932 - G11B7/0937 take precedence) · CPC title

• G03B2205/0069

  using electromagnetic actuators, e.g. voice coils · CPC title

• G02B7/08

  adapted to co-operate with a remote control mechanism · CPC title