Patent ID: 7645013
Filing Date: 2010-01-12
Classification: B41J

Abstract:
1. An image recording apparatus wherein an image is recorded on a recording medium being transported, by ejecting ink droplets from plural ink ejection ports provided in a recording head, the apparatus comprising: a transport member for transporting a recording medium supported on a surface thereof to an image forming position defined by the recording head; a drive unit that drives the transport member in a transporting direction of the recording medium; a reference pattern provided on the surface of the transport member, said reference pattern comprising a plurality of X-shaped reference patterns formed of slant lines, the reference patterns being provided in a matrix-like form on a substantially entire surface of the transport member; a detecting unit that detects crossing points of said slant lines and detects the reference pattern being moved as the transport member is driven; a calculating unit that calculates a speed change of the transport member and a position shift in a direction perpendicular to the transporting direction of the transport member based on detection information from the detecting unit; and an ink ejection control unit that both simultaneously controls output timing of ink droplets ejected from the plural ink ejection ports so as to correct for the influence of the speed change of the transport member based on a result of the calculation of the speed change of the transport member by the calculating unit and controls ejection positions of the ink droplets ejected from the plural ink ejection ports so as to correct for the influence of the position shift in the direction perpendicular to the transporting direction of the transport member based on a result of the calculation of the position shift in the direction perpendicular to the transporting direction of the transport member by the calculating unit; the detecting unit including a reference pattern detecting sensor having a sensor surface including a plurality of optical sensors arranged along a widthwise direction of the reference pattern detecting sensor and having a width generally equal to that of the recording head, and the range of detection by the plurality of optical sensors is set to be wider than a width of the transport member, and the calculating unit providing real time correction of the influence of speed change and/or skew/walk of the transport member and the influence of the orientation of each sheet of recording medium so that high quality image recording can be achieved at an appropriate position on the recording medium.