Variable focal length lenses
US6347742B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 2001 |
| Grant date | Feb 19, 2002 |
| Priority date | — |
| Expiry date | Jan 16, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/10811
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A bar code reader for an automated storage library has a lens assembly with a pair of polarized liquid crystal lenses. Each lens has pair of parallel glass plates that are separated by upper and lower glass substrates. A series of polymer films are symmetrically spaced apart between the substrates. Both the substrates and the films are perpendicular to the glass plates. Electrodes are formed on the films and combine to form a semi-cylindrical stack of film. Liquid crystal fills the spaces between adjacent pairs of the films. The films are coated and/or treated by an alignment process to predispose the liquid crystals to a specific rotational direction. When a selected voltage is applied between adjacent ones of the electrodes, the liquid crystals are synchronously rotated to alter their refractive index to a desired value. Thus, when the layers of each lens are manipulated in unison, the bar code reader is able to quickly adjust its focal length to read bar codes at various distances.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.