Print sequence scheduling system for duplex printing apparatus

In a simplex-duplex printer comprising an imager for creating images on a side of a sheet, and an inverter for inverting the sheet to enable the imager to create an image on another side of the sheet to make a duplex print, the inverter including a duplex loop for temporarily retaining the sheet, a method for scheduling a sequence of images created by the imager, comprising the steps of:

• providing a data structure including a schedule having a plurality of pitch spaces;
• for each simplex print to be made by the printer, entering into a pitch space in the schedule a simplex block representative of the creation of the simplex print;
• for each duplex print to be made by the printer, entering into pitch spaces in the schedule a duplex block representative of the creation of the duplex print, the duplex block comprising a front block representative of the creation of a first side of the duplex print and an end block representative of the creation of a second side of the duplex print, the front block and end block of each duplex block being spaced by a predetermined number of pitch spaces;
• accumulating a sequence of simplex blocks and end blocks corresponding to a desired sequence of simplex and duplex prints to be made in a forward sequence;
• providing a transition table, the transition table being a table of possible new end sequences of the predetermined number of pitch spaces at the end of the forward sequence, each new end sequence resulting from addition of either a simplex block or a duplex block to a previous end sequence;
• and
• for each new print accumulated in the schedule, adding an appropriate simplex or duplex block to a current end sequence in the transition table, to yield a new end sequence of the predetermined number of pitch spaces.

In a printing apparatus for creating monochrome and multicolor prints, the printing apparatus including a rotatable image receptor for accumulating print material in imagewise fashion, a plurality of selectably-actuable development units disposed along a path of the image receptor for dispensing print material onto a latent image created on the image receptor, and an imager disposed along the path of the image receptor for creating latent images on the image receptor, the printing apparatus being controllable to cause the imager to create partial images of a desired multicolor image and to enable print material relating to a plurality of partial images to be superimposed on an image area of the image receptor by causing print material relating to partial images to be retained on the image receptor through a plurality of rotations of the image receptor, a method for scheduling a sequence of latent images created by the imager, comprising the steps of:

• providing a data structure including a schedule having a plurality of pitch spaces;
• for each monochrome print to be made by the printer, entering into a pitch space in the schedule a simplex block representative of the creation of the monochrome print;
• for each multicolor print to be made by the printer, entering into pitch spaces in the schedule a complex block representative of the creation of the multicolor print, the complex block comprising at least a first block representative of the creation of a first partial image of the multicolor print and an end block representative of the creation of a final partial image of the multicolor print, the first block and end block of each complex block being spaced by a predetermined number of pitch spaces;
• organizing a plurality of simplex blocks and complex blocks within the schedule so that a sequence of simplex blocks and end blocks corresponds to a desired sequence of monochrome and multicolor prints to be output;
• and
• optimizing the sequence of simplex blocks and end blocks to minimize a number of blank pitch spaces within the schedule.