# US 2008/0186589 A1 · Compact Stepping Lens Actuator for Mobile Cameras > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0186589 A1 - Document ID: US20080186589A1 - Status: Published application - Kind: A1 - Application number: 11/911,014 - Filed: 2006-04-24 - Published: 2008-08-07 - Earliest claimed: 2005-04-29 - Assignees: Koninklijke Philips Electronics N.V. - Inventors: Gerardus L.M. Jansen; Rudy J.H. Van Den - Web page: https://patentgrep.com/patent/US20080186589A1 ## CPC - G02B 7/04: with mechanism for focusing or varying magnification - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An actuator (100) including: a housing (102); a driven member (104) movably disposed with respect to the housing; a magnet (114) associated with the driven member and a ferric member (112) for providing a magnetic attraction force between the driven member and the ferric member for providing a normal force (Fn) between the housing and driven member such that a friction force between the housing and driven member resulting from the normal force must be overcome to initiate a relative movement between the housing and driven member; and a magnetic drive system (118, 120) for overcoming the friction force and driving the driven member relative to the housing. The driven member can be a lens holder for holding a lens (106), in which case, the actuator can further include an image sensor (110) for acquiring image data through the lens. ## Claims ### Claim 1 An actuator (100) comprising: a housing (102); a driven member (104) movably disposed with respect to the housing; a preloading means (112, 114) for providing a normal force (Fn) between the housing and driven member such that a friction force between the housing and driven member resulting from the normal force must be overcome to initiate a relative movement between the housing and driven member; and a driving means (118, 120) for overcoming the friction force and driving the driven member relative to the housing. ### Claim 2 (depends on 1) The actuator of claim 1, further comprising a bearing (108) disposed between the housing and driven member, wherein the preloading means provides the normal force on the bearing. ### Claim 3 (depends on 1) The actuator of claim 1, wherein the driven member is a lens holder for holding a lens (106). ### Claim 4 (depends on 3) The actuator of claim 3, further comprising an image sensor (110) for acquiring image data through the lens, wherein the relative movement of the lens holder provides one of a focus and zoom adjustment for the image sensor. ### Claim 5 (depends on 1) The actuator of claim 1, wherein the preloading means comprises a magnet (114) associated with the driven member and a ferric member (112) for providing a magnetic attraction force between the driven member and the ferric member, wherein the magnetic attraction force is substantially equal to the normal force. ### Claim 6 (depends on 5) The actuator of claim 5, wherein the preloading means comprises two or more magnets. ### Claim 7 (depends on 5) The actuator of claim 5, wherein the magnet is a multipole magnet. ### Claim 8 (depends on 5) The actuator of claim 5, wherein the ferric member is a mounting plate (112) attached to the housing, the mounting plate containing a ferric material. ### Claim 9 (depends on 4) The actuator of claim 4, wherein the driving means comprises a magnetic drive system (118, 120). ### Claim 10 (depends on 9) The actuator of claim 9, wherein the magnetic drive system comprises: a drive coil (118), the magnet generating a field in the drive coil; and control means (120) for generating a drive current in the drive coil to generate a drive force (FD+, FD−) on the driven member which overcomes the friction force and results in a relative movement of the driven member. ### Claim 11 (depends on 10) The actuator of claim 10, wherein the drive coil is disposed in the housing. ### Claim 12 (depends on 10) The actuator of claim 10, comprising two or more drive coils. ### Claim 13 A method for driving an actuator (100), the method comprising: providing a normal force (Fn) between a housing (102) and a driven member (104) such that a friction force between the housing and driven member resulting from the normal force must be overcome to initiate a relative movement between the housing and driven member; and overcoming the friction force to drive the driven member relative to the housing. ### Claim 14 (depends on 13) The method of claim 13, wherein the providing comprises providing a magnet (114) associated with the driven member and a ferric member (112) for providing a magnetic attraction force between the driven member and the ferric member, wherein the magnetic attraction force is substantially equal to the normal force. ### Claim 15 (depends on 14) The method of claim 14, wherein the overcoming comprises: generating a field in a drive coil (118) with the magnet; and generating a drive current in the coil to generate a drive force (FD+, FD−) on the driven member which overcomes the friction force and results in a relative movement of the driven member. ### Claim 16 (depends on 13) The method of claim 13, wherein the driven member is associated with a lens (106) and the method further comprises providing one of a focus and zoom adjustment between the lens and a camera (110) due to the relative movement between the driven member and housing. ### Claim 17 A lens actuator (100) for a camera system, the lens actuator comprising: a housing (102); a lens holder (104) for holding a lens (106), the lens holder being movably disposed with respect to the housing; a camera (110) in optical communication with the lens; a preloading means (112, 114) for providing a normal force (Fn) between the housing and lens holder such that a friction force between the housing and lens holder resulting from the normal force must be overcome to initiate a relative movement between the housing and lens holder; and a driving means (118, 120) for overcoming the friction force and driving the lens holder relative to the housing. ### Claim 18 (depends on 17) The lens actuator of claim 17, further comprising a bearing (108) disposed between the housing and lens holder, wherein the preloading means provides the normal force on the bearing. ### Claim 19 (depends on 17) The lens actuator of claim 17, wherein the preloading means comprises a magnet (114) associated with the lens holder and a ferric member (112) for providing a magnetic attraction force between the lens holder and the ferric member, wherein the magnetic attraction force is substantially equal to the normal force. ### Claim 20 (depends on 19) The lens actuator of claim 19, comprising two or more magnets. ### Claim 21 (depends on 19) The lens actuator of claim 19, wherein the magnet is a multipole magnet. ### Claim 22 (depends on 16) The lens actuator of claim 16, wherein the ferric member is a mounting plate (112) attached to the housing, the mounting plate containing a ferric material. ### Claim 23 (depends on 15) The lens actuator of claim 15, wherein the driving means comprises a magnetic drive system (118, 120). ### Claim 24 (depends on 23) The lens actuator of claim 23, wherein the magnetic drive system comprises: a drive coil (118), the magnet generating a field in the drive coil; and control means (120) for generating a drive current in the drive coil to generate a drive force (FD+, FD−) on the driven member which overcomes the friction force and results in a relative movement of the lens holder. ### Claim 25 (depends on 24) The lens actuator of claim 24, wherein the drive coil is disposed in the housing. ### Claim 26 (depends on 24) The lens actuator of claim 24, comprising two or more drive coils.