Lens driving apparatus and method

摘要

A lens driving apparatus for a lens includes a voice coil motor. A coil position of a coil is detected. A table memory stores a correction factor for each one of plural values of the coil position according to flux density distribution. The correction factor is read from the table memory according to the detected coil position. A coil current is corrected by use of the correction factor for each coil position. The corrected coil current is caused to flow through the coil, with which the lens is moved together along an optical axis. Consequently, changes in a moving speed of the lens can be prevented.

主权项

1. A lens driving apparatus for a lens supported in a lens holder movable in an optical axis direction, comprising:
a voice coil motor, having a magnet extending in said optical axis direction, and a coil disposed in a magnetic field of said magnet and coupled to said lens holder, for generating electro-magnetic force by flow of a coil current, to move said lens holder together in said optical axis direction; a position detector for detecting a coil position of said coil relative to said magnet in said optical axis direction; a first table memory for storing a first correction factor for compensating for a low level area in flux density distribution of said magnet in said optical axis direction in relation to respectively said coil position; an initial flux density memory for storing initial flux density of said magnet set in a reference position; a flux density measurer for measuring monitored flux density of said magnet in said reference position; a flux density ratio determiner for determining a flux density ratio between said initial flux density and said monitored flux density being measured by said flux density measurer; a factor modification unit for modifying said first correction factor stored in said first table memory by use of said flux density ratio in relation to respectively said coil position; a controller for correcting said coil current according to said first correction factor read out from said first table memory according to said coil position detected by said position detector.