Lens drive control apparatus
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsNorio Numako, Naoto Nakahara
Life of this patent
Estimating the term…
Abstract
A lens drive control apparatus includes a movable lens which is movable along the optical axis; a lens driver; a code plate having two limit positions respectively serving as mechanical movement limit positions of the movable lens, the code plate including first and second codes; a code detector which moves together with the movable lens; a pulse generator which generates pulses according to the movement of the movable lens; a pulse counter; and a position determining device which determines an absolute position of the first code detected by the code detector, based on the number of pulses counted by the pulse counter from the time when the code detector detects the first or second code until the time when the code detector detects the subsequent other of the second code or first code.
Claims19
A lens drive control apparatus comprising:
- a movable lens which is movable along the optical axis;
- a lens driver which moves said movable lens;
- a code plate having two limit positions respectively serving as mechanical movement limit positions of said movable lens, said code plate comprising first codes corresponding to each of a plurality of predetermined stop positions at which said movable lens is stopped between said two limit positions, and second codes corresponding to each of predetermined positions respectively provided between said limit positions and said plurality of predetermined stop positions;
- a code detector which moves together with said movable lens in order to detect said first and second codes;
- a pulse generator which generates pulses according to the movement of said movable lens;
- a pulse counter which counts the number of pulses generated by said pulse generator;
- and
- a position determining device which determines an absolute position of said first code detected by said code detector, based on the number of pulses counted by said pulse counter from the time when said code detector detects one of said first code and second code until the time when said code detector detects the subsequent other of said second code and first code, while said lens driver moves said movable lens toward one of said two limit positions.
Dependencies are inferred from the claim text.