Patent ID: 7782546

Claim:
A zoom lens, comprising: a base; a cam roll being defined with an original position, rotated about an optical axis at the original position and disposed on the base, comprising a plurality of cam grooves, a datum point disposed along a circular direction, and at least one skew point; a plurality of straight-forward units being respectively parallel to the optical axis and fixed at the base; a plurality of lens groups moved by the cam roll to sequentially vary from a receiving status to a zeroing status, a macro shooting-distance status and a wide shooting-distance status, each of the plurality of lens groups being jacketed on one of the plurality of straight-forward units and driven by one of the plurality of cam grooves of the cam roll and comprising a group box movable along a direction of the optical axis and at least one lens securely disposed on the group box, wherein the datum point of the cam roll corresponds to the zeroing status of the plurality of lens groups, and a position of the skew point is configured as a skewing status corresponding to a duration between the macro shooting-distance status and the wide shooting-distance status of the plurality of lens groups; a driving unit installed on the base, comprising a driving portion and a decelerating system driven by the driving portion, wherein the driving portion drives the cam roll to be rotatable at the original position so that the plurality of lens groups are reciprocally switched between the receiving status and the wide shooting-distance status; a detecting unit disposed on the base, comprising an impeller driven by the driving portion of the driving unit, a detecting portion utilized to detect the rotation of the impeller with a rotation count, and a photonic sensor utilized to detect the datum point and the at least one skew point of the cam roll; and a micro-processing unit electrically connected to the driving unit and the detecting portion and the photonic sensor of the detecting unit; when the photonic sensor of the detecting unit detects the datum point of the cam roll, a signal emitted from the photonic sensor of the detecting unit is provided for the micro-processing unit to determine the position of the datum point of the cam roll and zero the rotation count of the impeller; and when the photonic sensor of the detecting unit detects the at least one skew point of the cam roll, a skew signal emitted from the photonic sensor of the detecting unit is provided for the micro-processing unit to determine whether the rotation count of the impeller meets a predetermined value or not, and the micro-processing unit amends the rotation count of the impeller to be equal to the predetermined value if the rotation count of the impeller is not equal to the predetermined value.