Patent ID: 6636353
Filing Date: 2003-10-21
Classification: G02B

Abstract:
An optical element change-over control apparatus comprising:an optical element change-over member capable of holding a plurality of optical elements and rotating alternatively to locate a specific optical element on an optical path; a driving element for rotating the optical element change-over member; a positioning detecting element for detecting the selected optical element being positioned so that the optical element stays in a predetermined position on the optical path and outputting positioning signals; an origin detecting element for detecting the point of origin of the optical element change-over member; and a control element for driving the driving element to rotate the optical element change-over member and counting the positioning signals delivered from the positioning detecting element during the time interval that elapses from the instant that the point of origin of the optical element change-over member is first detected by means of the origin detecting element until the point of origin of the optical element change-over member is secondly detected by means of the origin detecting element, thereby detecting the number of change-over stages of the optical element change-over member.