Laser beam scanning apparatus having a variable focal distance device and the variable focal distance device for use in the apparatus
US5289001A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Dec 22, 1992 |
| Grant date | Feb 22, 1994 |
| Priority date | — |
| Expiry date | Dec 22, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/1135
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a variable density scanning apparatus, a variable focal distance device is provided in a scanning optical system. This variable focal distance device is formed of a light waveguide having a plurality of electrodes provided of which the lengths along the direction of incident laser beam are decreased or increased with the increase of the distance from the central electrode. The voltage to be applied between the electrodes is controlled in accordance with a desired dot pattern so as to change the refractive index of the light waveguide through which the laser beam is passed, thereby effectively changing the focal distance so that the diameter of the scanning laser beam spot can be changed in one dimension.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.