Method and device for focus adjustment of optical writing unit and image forming apparatus incorporating the focus adjustment device
US7154525B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 2003 |
| Grant date | Dec 26, 2006 |
| Priority date | — |
| Expiry date | Mar 29, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G2215/00033
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Focus adjustment of an optical writing unit is performed based on an image of a test pattern formed on a paper sheet. The pattern includes bars of density levels associated with adjustment quantity information indicating numerical values corresponding to the numbers of rotation of adjustment motors and adjustment screws. The density levels decrease as the amount of displacement of the unit with respect to a photosensitive drum increases. A focus adjustment device accepts an input of the numerical values indicated beside the unprinted bars of the lowest density levels and causes the motors to turn by the numbers of rotation indicated by the input numerical values to move the unit to the position of correct focus. It is possible to perform focus adjustment of the unit with ease and high accuracy regardless of whether the unit is for forming binary or multi-valued images.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.