Patent ID: 8577217

Claim:
A tilt preventing structure for an electromagnetic driving device, the tilt preventing structure being defined with a central axis, the tilt preventing structure comprising: a casing having a receiving space therein; a driven object received in the receiving space and capable of moving within the casing and along the central axis, further including a guiding hole located at one corner thereof and a guiding groove located at another corner thereof opposing diagonally to the guiding hole; a guiding mechanism positioned in the receiving space of the casing and connected to the driven object for guiding the driven object to move along the central axis, further including two guiding rods coupled to the guiding hole and the guiding groove; and an electromagnetic driving module comprising three magnetic elements coupled to the driven object, each of the three magnetic elements being attached to a corresponding corner of the driven object from outside and located in position to one of three coils disposed on the casing, respectively; wherein the another corner of the driven object is a corner not having any of the three magnetic elements to be mounted thereon; wherein the guiding rod accommodated in the guiding hole comprises a magnetically susceptible material and is positioned proximate to a middle one of the three magnetic elements by a shortest distance less than 5 mm, such that the middle one of the three magnetic elements exerts a magnetic attraction force upon the guiding rod accommodated in the guiding hole to cause the driven object to abut against the guiding rod and thereby reduce a dynamic tilt occurring to the driven object while the driven object is moving along the guiding mechanism.