Patent ID: 6941083

Claim:
An image forming apparatus having an image deviation correction function, comprising: an image forming portion having a toner image forming unit to form a toner image on an image carrying member, a transfer unit for transferring the toner image on the image carrying member to a recording medium, a fixing unit for heating and fixing the toner image on the recording medium, and a re-conveying unit for re-conveying the recording medium with the toner image fixed on to the transfer unit, wherein the toner image can be formed on both sides of the recording medium; a first memory unit to store correction patterns for image adjustment when forming the toner image on the both sides of the recording medium; a measured member on which the correction patterns are printed; an image adjustment controller to control the toner image forming unit so as to print a pair of the correction patterns respectively on the recording medium and the measured member in a main scanning direction; first measuring means for measuring passing waveforms of the paired correction patterns printed on the measured member; second measuring means for measuring passing waveforms of the paired correction patterns printed on the recording medium and then heated and fixed by the fixing unit; a calculator to calculate a second ratio of “non-printed part passing time in a total length of the correction pattern” to “passing time through the total length of the pattern” from the second measured results by the second measuring means and from the calculation results, calculating a correction value of a main scanning magnification of the toner image and a correction value of a main scanning reference position at the time of toner image forming on a first side of the recording medium and at the time of toner image forming on a second side; a second memory unit to store the correction value of the main scanning magnification and the correction value of the main scanning reference position; and a correction controller to, when form toner images on both sides of the recording medium, apply the correction value of the main scanning magnification and the correction value of the main scanning reference position to the toner image on either of the first side and the second side and control deviation correction in the main scanning direction.