DEVICE FOR CONTROLLING AUTO CONVERGENCE OF SMALL OPTICAL LENS

摘要

An automatic focus control device of a small optical lens is provided to cut down the cost for a magnetic circuit unit, by forming the magnetic circuit unit with a cheap bonded permanent magnet and coils, and installing a simple additional circuit unit made of soft magnetic materials. An automatic focus control device(80) of a small optical lens is composed of a driving unit having a lens holder(59) in which a lens assembly(51) is combined; a spring unit returning the driving unit to the initial position; a magnetic circuit unit(55) comprising a permanent magnet(55b) generating a magnetic flux all the time and a coil(55a) moving the driving unit by magnetic force generated inside; and a housing(54) combining single parts into one. The bonded permanent magnet is installed at the driving unit and the coil is separately installed at the outside of the bonded permanent magnet, to move the driving unit by applying repulsive force to the bonded permanent magnet through the magnetic force. An additional circuit unit(57) is installed at the outside of the coil of the magnetic circuit unit to generate new drag force together with the bonded permanent magnet by applying the magnetic force of the coil.