Modulating laser intensity in a laser printer proportionately to the velocity of the photoconductive media
US4835545A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1987 |
| Grant date | May 30, 1989 |
| Priority date | — |
| Expiry date | Nov 30, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K15/1209
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A photosensitive, photoconductive media moving in a first direction relative to a laser light beam scanning in a second direction, transverse to the first direction, incurs velocity variations. These velocity variations result in variations in the absolute and relative heights of white and black image features. This printed image nonuniformity is especially visually detectable for closely spaced parallel lines in the second direction, and/or gray scale. An optical velocity sensor senses instantaneous media velocity. An analog or digital velocity error processor maintains a running average velocity and determines, by subtraction, an instantaneous velocity error as the difference between currently sensed and running average velocities. The instantaneous velocity error so determined is used to adjust the intensity of the laser light beam to be proportionally brighter (dimmer), exposing a wider (narrower) scan line, on a faster-moving (slower-moving) media region. By this compensating, the ratio of white and black image features is maintained constant during media velocity variations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.