Patent ID: 9500838
Filing Date: 2016-11-22
CPC Classification: G02B,H02K,H02P

Claim Text:
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.