| CPC G03B 13/36 (2013.01) [G03B 2205/0069 (2013.01)] | 8 Claims |
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8. A method for positional control of a zoom actuator, said zoom actuator comprising a first carrier having attached thereto a first lens and a first magnet and movable along an optical axis, a second carrier having attached thereto a second lens and a second magnet, said second carrier being capable of moving anterior or posterior to the first carrier along the optical axis, a first coil unit facing the first magnet, a second coil unit facing the second magnet, and a plurality of Hall sensors facing the first magnet,
the method comprising the steps of:
a signal input step for receiving an output signal from each of the plurality of Hall sensors;
a position signal generating step for generating a position signal for the first carrier by carrying out operations on the output signals; and
a positional control step for controlling a position of the first carrier using the position signal; and
wherein the plurality of Hall sensors is disposed along the optical axis at positions differing in their distances displaced from an interpolar boundary of the first magnet,
wherein the first magnet has m magnetic poles (m being a natural number equal to or greater than 3) facing the first coil unit, and
wherein at a default position of the first carrier, the position signal generating step carries out on the position signals, either additive operation when the plurality of Hall sensors is facing together a same magnetic pole of the first magnet, or a subtractive operation when each of the plurality of Hall sensors is facing a different magnetic pole of the first magnet.
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