Method and apparatus for electronic collation

Abstract

A method and apparatus are disclosed for electronic collation of sheets of a recording medium, such as paper, printed on one or both sides from electrical signals received at a printer. For printing multiple sets on one side only, the signals are written into a memory in the order in which they are received. The first set may be printed in the desired page order on a recording medium fed through the printer as the signals are received. Additional sets are printed in the same page order by writing the contents of the memory into the printer as many times as necessary as the recording medium is fed through the printer. For printing multiple sets on both sides, the signals representative of every other page are written into the memory and organized into two ordered sequences. One of these sequences contains the electrical signals representative of each of the pages to be printed on one side of the recording medium and the other sequence contains the electrical signals to be printed on the other side of the recording medium. Within each sequence the order of the signals is such that the signals representative of adjacent pages in the order to be printed are adjacent one another in the sequence. Again, the first set may be printed in the desired page order as the signals are received. Each additional set is printed in the desired page order by writing first one sequence and then the other into the printer with one sequence being written in the opposite page order to that in which the signals are received. While the first sequence is being written, the recording medium to be printed is fed through the printer into a last-in-first-out (LIFO) receptacle along a feed path that effectively turns it over. While the second sequence is being written, it is fed from the LIFO sheet receptacle, back through the printer, to an output receptacle.