Method of printing images on halves of both sides of sheets by passing each sheet seriatim four times directly in succession through a printing station (4), thereby printing the four halves of the sheet. The sheets thus printed and together folded double form a book in which the sequence of the images corresponds to the sequence of the original images.
A device for performing this method comprises a sheet turn-over path (8) along which a sheet passed through the printing station (4) can be returned to the printing station and a sheet discharge path (7) along which a sheet passed through the printing station (4) can be fed to a collector tray (12). Control means control that a sheet after the first three passes is fed into the turn-over path (8) and after the fourth pass into the discharge path (7) and a time element so controls the time of passage of a sheet through the printing sta­tion (4) that on the first and fourth pass of a sheet an image is printed on a half of the sheet which, as considered in the direction of passage, is other than the half printed in the second and third pass of the sheet.
For making a book from a set of originals printed on one side the device is provided with a document feeder (21,22) for feeding origi­nals from both sides of a stacked set of originals (20) and a deposit device (29) having two deposit plates (30,31), in which, for printing a sheet, first two originals are fed from one side of the stack (20) and deposited on one of the deposit plates (30,31) and then two ori­ginals are fed from the other side of the stack (20) and deposited in reverse orientation on the other deposit plate.
For keeping the last page(s) of a book blank when the number of ori­ginals is less than a multiple of four, the document feeding opera­tion can be inhibited at appropriate times in a print cycle being otherwise the same.