color image-forming device
US6188419A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 17, 1998 |
| Grant date | Feb 13, 2001 |
| Priority date | — |
| Expiry date | Aug 17, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/506
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In conventional color digital copy machines, when copying in color mode, the polygon mirror of the laser beam scanner for black, which is driven at a higher speed than those of the other colors, is switched to a slower speed in conformity with the speed of the polygon mirrors for the other colors. However, a drawback of this structure is that, especially when switching from monochrome to color mode, the time required to obtain the first copy is lengthened, and the operating efficiency of copying is poor. In the present invention, when copying in color mode, the rotation speed of the polygon mirror of the laser scanner unit for black is not changed at all, but, by skipping certain mirror surfaces of the polygon mirror, and/or by skipping certain of a plurality of laser light sources, the scanning density of the laser scanner unit for black can be brought into conformity with that of the laser scanner units for the other colors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.