An electromagnetic driving device for lens having an anti-tilt mechanism, defined with an X axis, a Y axis and a Z axis, comprising:
- a casing;
- a frame, housed by the casing so as to form an inner compartment thereinside;
- a driven object, received inside the inner compartment, allowed to shift in the casing along the Z axis;
- a driving module, located between the casing and the driven object, used to drive the driven object to shift in the casing along the Z axis;
- and
- an anti-tilt mechanism, located at the frame at a position respective to the driven object, used to eliminate X-axial or Y-axial gaps around the driven object inside the inner compartment;
- wherein said anti-tilt mechanism further includes two opposing grooves located at a rim of the driven object, a constraint block located at the frame, a plurality of rolling members and an elastic pre-stress structure, a number of the rolling members being feed inside a space formed by one of the grooves and the constraint block while the other rolling members are feed inside another space formed by another one of the grooves and the elastic pre-stress structure, wherein the two grooves and the constraint block are extended in directions parallel to the Z axis;
- wherein said groove is one of a V-shape race and a U-shape race, the constraint block is one of a concave V-shape race or a concave U-shape race, X-axial and Y-axial kinetic tilt of the driven object while in moving inside the inner compartment along the Z axis are eliminated by having the elastic pre-stress structure to depress the respective rolling members in the corresponding groove, and the rolling member is one of at least one rolling ball, at least one rolling pin, at least one slippery rod and at least one cam;
- further including a constraint member formed as a frame located inside the casing to separate the rolling members and so as to avoid possible collisions by adjusting contact points of the rolling members on the driven object, wherein the constraint member is one of a magneto-conductive material and a non-magneto-conductive material;
- and
- wherein the elastic pre-stress structure further includes:
- a loosen-fit backing plate, being loosely fit into an opening of the frame, the opening communicating in space with the inner compartment, the loosen-fit backing plate further having a slippery rack respective to one of the grooves of the lens module, the slippery rack being one of a V-shaped race and a U-shaped race;
- and
- a spring plate, further having an X-directional spring plate and a Y-directional spring plate extending perpendicular to the X-directional spring plate, the X-directional spring plate being located in a slim space between the inner loosen-fit backing plate and the outer casing, the Y-directional spring plate being extended into a predetermined backlash at one side of the opening and between the loosen-fit backing plate and the frame;
- wherein, by providing the slippery rack and the corresponding groove to feed therebetween the rolling members, by having the X-direction spring plate of the spring plate to elastically depress the loosen-fit backing plate onto the driven object, and further by having the Y-direction spring plate to elastic fill the backlash between the loosen-fit backing plate and the frame, both the X-axial and Y-axial gaps (kinetic tilt) between the lens module and the frame while the driven object shift along the Z axis inside the inner compartment are substantially eliminated.