Image forming apparatus, method of adjusting image positional deviation, and computer program product

A method of adjusting an image positional deviation, comprising:

• conveying a recording medium;
• moving a movable body in a main-scanning direction orthogonal to a conveying direction of the recording medium, the movable body including a recording head to eject a liquid droplet for image recording to the recording medium and being supported movably in the main-scanning direction;
• recording a plurality of adjustment patterns with a predetermined edge interval in the main-scanning direction by causing the liquid droplet ejected from the recording head to land on the recording medium, while moving the movable body in the main-scanning direction;
• reading, by a reading unit mounted on the movable body, the adjustment patterns by irradiating the recording medium on which the adjustment patterns are recorded with read light and photoelectrically converting reflected light from the recording medium;
• calculating a positional deviation correction amount for correcting a deviation of a landing position of the liquid droplet, which is ejected from the recording head and landed on the recording medium, based on an ideal interval between the adjustment patterns recorded on the recording medium and a read result of the adjustment patterns read at the reading;
• correcting that includes recording the adjustment pattern at a recording position where the interval between the adjustment patterns becomes an integral multiple of a fluctuation cycle in a relative movement of the reading unit and the adjustment pattern, which is caused by movement of the movable body mounted with the reading unit, and correcting the recording position of the adjustment pattern based on the positional deviation correction amount calculated at the calculating;
• and
• adjusting an ejection timing of the liquid droplet by the recording head by performing repeatedly at least twice the recording, the reading, the calculating, and the correcting.

A computer program product comprising a non-transitory computer-readable medium containing a computer program for adjusting an image positional deviation, the program causing a computer to perform:

• causing a recording medium to be conveyed;
• causing a movable body to be moved in a main-scanning direction orthogonal to a conveying direction of the recording medium, the movable body including a recording head to eject a liquid droplet for image recording to the recording medium and being supported movably in the main-scanning direction;
• causing a plurality of adjustment patterns to be recorded with a predetermined edge interval in the main-scanning direction by causing the liquid droplet ejected from the recording head to land on the recording medium, while causing the movable body to be moved in the main-scanning direction;
• causing a reading unit mounted on the movable body to read the adjustment patterns by causing the recording medium on which the adjustment patterns are recorded to be irradiated with read light and photoelectrically converting reflected light from the recording medium;
• calculating a positional deviation correction amount for correcting a deviation of a landing position of the liquid droplet, which is ejected from the recording head and landed on the recording medium, based on an ideal interval between the adjustment patterns recorded on the recording medium and a read result of the adjustment patterns read at the reading;
• correcting that includes recording the adjustment pattern at a recording position where the interval between the adjustment patterns becomes an integral multiple of a fluctuation cycle in a relative movement of the reading unit and the adjustment pattern, which is caused by movement of the movable body mounted with the reading unit, and correcting the recording position of the adjustment pattern based on the positional deviation correction amount calculated at the calculating;
• and
• adjusting an ejection timing of the liquid droplet by the recording head by performing repeatedly at least twice the recording, the reading, the calculating, and the correcting.