| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that a person who wears conventional multifocal spectacles in which a plurality of lenses differing in focal length are provided in a single lens needs to change his or her visual line or focal lengths of the lenses themselves when viewing an object at hand or an object at a distance. SOLUTION: The multifocal spectacles are equipped with vari-focus lenses and a driving unit driving the vari-focus lenses, wherein each of the vari-focus lenses has a first lens having a positive or negative focal length and a second lens which is disposed on the optical axis of the first lens and varies in focal length when voltage is applied thereto, and the driving unit has an application means for repetitively applying a plurality of preset voltage values to the second lens stepwise in predetermined cycles. Consequently, the vari-focus lens is switched between two or more kinds of focal length repeatedly stepwise in such cycles that the wearer can not recognize the switching, thereby providing the multifocal spectacles. COPYRIGHT: (C)2007,JPO&INPIT
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