Patent ID: 7854489
Filing Date: 2010-12-21
Classification: B41J

Abstract:
1. An image forming apparatus comprising: a carriage having a recording head for jetting liquid droplets; a pattern forming unit configured to form, on a conveying belt, an adjustment pattern used for detecting displacement of landing positions of the liquid droplets; a reading unit mounted on the carriage, including a light emitting unit and a light receiving unit, and configured to scan and read the conveying belt before the adjustment pattern is formed thereon so as to output a first reading result, and scan and read the adjustment pattern on the conveying belt so as to output a second reading result; a correcting unit configured to correct the displacement of the landing positions based on the second reading result; a frequency analyzing unit configured to calculate frequencies of a surface of the conveying belt and amplitudes of respective frequency components thereof based on the first reading result; and a peak frequency calculating unit configured to calculate one or more peak frequencies of the surface of the conveying belt based on the frequencies of the surface of the conveying belt and the amplitudes of the frequency components, the peak frequencies being one or more of the frequency components whose amplitude exceeds a predetermined level; wherein the pattern forming unit forms the adjustment pattern at a frequency different from the peak frequencies.