Adjustable focus eyeglasses

摘要

Adjustable focus eyeglasses with two lens units, each lens unit having two lens elements. The eyeglasses are focused by adjusting the position of at least one of the two lens elements relative to the other in a direction generally perpendicular to a viewing direction. The relative motion can be linear or pivotal about a pivot location outside the lenses. Applicant provides basic general equations defining the thickness profiles for the lenses and the solutions to these equations are: $t=A\left[{\mathrm{uv}}^2+2\left(\mathrm{alpha}v+1\right)\left(\mathrm{alpha}u-\sin \left(\mathrm{alpha}u\right)\right)/{\mathrm{alpha}}^3\right]+B\left[2\left(\mathrm{alpha}v+1\right)\left(1-\cos \left(\mathrm{au}\right)\right)/{\mathrm{alpha}}^2\right)\text{]}+C\left(v\sin \left(\mathrm{au}\right)/\mathrm{alpha}-\left(\mathrm{alpha}u-\sin \left(\mathrm{alpha}u\right)\right)/{\mathrm{alpha}}^2\right)\text{]}+\mathrm{Du}+E+F\left(v\right)+F1\left(u,v\right)u^4+F2\left(v\right)u^{3}v+F3\left(v\right)u^2{v}^2+F4\left(v\right){\mathrm{uv}}^3,$ where A for one of the lenses elements is -A for the other lens element in each lens unit and F(v), F1(u,v), F2(v), F3(v), F4(v) are any functions over the area of the lenses for which derivatives up to at least third order are continuous. At least one of F1(u,v), F2(v), F3(v), F4(v) is non-zero.