Patent ID: 6785011
Filing Date: 2004-08-31
Classification: B41J,G06K,H04N

Abstract:
In an image forming apparatus utilizing a laser beam which executes a scan pattern of repeated transverse scans along a longitudinal line to form images on recording media, a process of determining the start of scan and the longitudinal beam position, comprising the steps of:determining the time at which is laser beam reaches a first surface; determining the time at which the laser beam reaches a second surface which second surface extends obliquely to the first surface; averaging the two determined times to determine a start of scan reference time; forming the difference between the two determined times, deriving, from the difference between the two determined times, the longitdinal beam position; supplying a second laser beam; determining the time at which the second laser beam reaches a third surface; determining the time at which the second laser beam reaches a fourth surface, the fourth surface extending obliquely to the third surface; averaging the two determined times at which the second laser beam reaches a third surface and a fourth surface, respectively, to determine a start of scan reference time; forming the difference between the two determined times at which the second laser beam reaches a third surface and a fourth surface, respectively, deriving, from the difference between the two determined times at which the second laser beam reaches a third surface and a fourth surface, respectively, the longitudinal beam position of the second laser beam.