Image forming apparatus having a duplex path and/or an inverter

Image forming apparatus comprising:

• a finite length image member,
• means for forming a series of toner images on the image member, which series of toner images have a frame length equal to a distance between a point in one image and a comparable point in the next image,
• means for holding a supply of receiving sheets, each sheet having first and second sides,
• a transfer station including means for transferring a toner image from the image member to a first side of a receiving sheet,
• means for feeding a receiving sheet from the means for holding to the transfer station with the first side of the receiving sheet oriented to receive a toner image,
• means for feeding one or more receiving sheets through a finite length duplex path back to the transfer station to receive another toner image,
• means for inverting a sheet in the duplex path to change the side of the sheet being presented to a toner image at the transfer station,
• logic and control means for controlling the formation of the toner images on the image member and movement of the receiving sheets, said logic and control means including
• means for controlling image formation to form images in first, second and third frames having first, second and third different frame lengths, respectively, wherein the first frame length is approximately 1/2 the third frame length and the second frame length is more than the first frame length and less than the third frame length, and the finite length of the image member is an integer multiple of each of the frame lengths, and means for controlling movement of the sheets through the duplex path at a predetermined speed profile which is substantially the same for sheets bearing images formed in the first and third frames but is different for receiving sheets bearing images formed in the second frames.