Patent ID: 7545582

Claim:
An eyepiece for use with a viewing device, wherein the eyepiece is configured to change the distance between a first edge of the eyepiece and a lens near a second edge of the eyepiece, comprising: a first element having a pin extending therefrom and a rotational axis having a first axial direction and a second axial direction; and a second element having a groove, the second element sharing the rotational axis and configured to rotate about the rotational axis relative to the first element; wherein the groove comprises a first pin movement section and a second pin movement section, wherein the first and second pin movement sections cause the second element to move relative to the first element along the rotational axis in the first axial direction when the second element is rotated in a first rotational direction relative to the first element, wherein the first and second pin movement sections cause the second element to move relative to the first element along the rotational axis in the second axial direction when the second element is rotated in a second rotational direction relative to the first element; wherein the groove further comprises a pin stopping section, the pin stopping section located between the first pin movement section and the second pin movement section, wherein the pin stopping section prevents the second element from moving relative to the first element along the rotational axis in the first axial direction when the second element is provided rotational force in the first rotational direction relative to the first element, wherein the pin stopping section prevents the second element from moving relative to the first element along the rotational axis in the second axial direction when the second element is provided rotational force in the second rotational direction relative to the first element; wherein the pin stopping section is further configured to prevent the second element from rotating relative to the first element.