Optical system for producing an image for a set of characters
US4731854A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 17, 1986 |
| Grant date | Mar 15, 1988 |
| Priority date | — |
| Expiry date | Jul 17, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1018
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An optical system produces an image of a set of characters on a background. A flash light source directs uniform illumination toward the set of characters for a predetermined flash period having an intensity chosen to exceed the intensity of corrupting light from the environment, such as sun light, street lights or car lights. A first polarizer is positioned to polarize the illumination from the flash light source prior to the light impinging on the set of characters, and a second polarizer is positioned to receive light reflected by the set of characters and the background. The second polarizer is cross-polarized with respect to the first polarizer so that it filters out polarized light from the flash light source that is reflected by the set of characters and background. An optical receiver is positioned to receive light from the second polarizer and produces an image of the set of characters and the background. A shutter is used to control the light received by the optical receiver. The shutter is synchronized with the flash light source and the optical receiver to open and close during the flash so that the image produced by the optical receiver is dominantly produced by the de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.