Abstract: The invention provides a double-faced image formation system that prevents transfer and adhesion of a lubricant to an image retaining conveyer and an intermediate transfer part. The system is provided with, on a return path for reversing and conveying a sheet having toner images fixed on one side thereof, a front face electrifying unit and a rear face electrifying unit. Oil adhered on the rear face of the sheet in a fixation unit by the rear face electrifying unit is electrified to a negative polarity, and the oil adhered on the rear face is made impossible to transfer to an intermediate transfer belt. The oil adhered on the front face of the sheet in the fixation unit by the front face electrifying unit is electrified to a positive polarity, and the oil adhered on the front face is made impossible to transfer to a secondary transfer conveyance belt.

Abstract: The invention provides a double-faced image formation system that prevents transfer and adhesion of a lubricant to an image retaining conveyer and an intermediate transfer part. The system is provided with, on a return path for reversing and conveying a sheet having toner images fixed on one side thereof, a front face electrifying unit and a rear face electrifying unit. Oil adhered on the rear face of the sheet in a fixation unit by the rear face electrifying unit is electrified to a negative polarity, and the oil adhered on the rear face is made impossible to transfer to an intermediate transfer belt. The oil adhered on the front face of the sheet in the fixation unit by the front face electrifying unit is electrified to a positive polarity, and the oil adhered on the front face is made impossible to transfer to a secondary transfer conveyance belt.

Abstract: An image forming apparatus registers both sides of sheets with great precision in a sheet transportation direction in both-side image formation. The image forming apparatus includes: photoconductive drums holding toner images; an intermediate transfer belt temporarily holding the toner images; a secondary transfer roll that transfers the toner images to a sheet in a transfer unit; a registration roll rotating toward the transfer unit being in sheet feeding timing; a fixing unit fixing the toner images transferred to a first side of the sheet; reversion transportation paths reversing the sheet and again transporting the sheet to the transfer unit; a first sensor detecting the image of the first side of the sheet; and a second sensor that detects the toner images held in the intermediate transfer belt.

Abstract: Image formation condition is available, which hardly causes imperfections of the image quality. A full-color image formation system selects plural secondary transfer conditions in a secondary transfer unit within a specific range, forms test charts according to each of the secondary transfer conditions selected, and prints them out. A user checks by viewing the test charts printed on each recording sheet, and selects a page number of the sheet where the user evaluated an image quality as the best; and the image formation system sets the secondary transfer condition for the sheet as a standard secondary transfer condition thereafter.

Abstract: The present invention enables registration adjustments during actual use of an image forming apparatus. A test pattern is formed on a sheet in a full-color image forming apparatus and the test pattern formed on the sheet is read in an image read unit. From the result of reading the test pattern, misregistrations of vertical and horizontal scaling factors, parallelism, squareness, skew, side registration, and lead registration in the test pattern are determined, and mounting positions, drive timings, drive speeds, and the like of constituent members are adjusted.