Variable density scanning apparatus
US5053619A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | Mar 30, 1990 |
| Grant date | Oct 1, 1991 |
| Priority date | — |
| Expiry date | Mar 30, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/1135
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A variable density scanning apparatus comprises a semiconductor laser which generates at least one laser beam, a first drive circuit which applies to said semiconductor laser a modulation drive signal having a predetermined modulation frequency in accordance with the density of dots constituting the pattern to be formed on the scanning surface, a dynamic diffraction grating which receives a laser beam from said semiconductor laser and diffracts said laser beam into a plurality of diffraction beams, a second drive circuit which applies to said dynamic diffraction grating a diffraction drive signal having a predetermined high frequency in accordance with the dot density, a polygonal mirror which receives a plurality of diffraction beams from said dynamic diffraction grating and scans said diffraction beam in the main scanning direction, a third drive circuit which applies to said polygonal mirror a rotation drive signal having a predetermined rotation frequency in accordance with the dot density, and a control unit which applies to said first, second and third drive circuits respectively a control signal that indicates an instruction to change the dot density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.