Patent ID: 7103306

Claim:
A double-sided printing apparatus which prints slips on both sides of an elongated sheet having page breaks while transporting the sheet, and which is provided with a first printer for printing at least one slip on the obverse of the sheet and a second printer disposed downstream of a sheet transportation path for printing at least one slip on the reverse of the sheet, the double-sided printing apparatus comprising: a first printing control unit which, upon receiving printing data including page-number information for each of a plurality of slips, divides printing data for each slip into data to be printed on the obverse of the sheet in the first printer and data to be printed on the reverse side of the sheet in the second printer, and allows the first printer to print one slip per page or sequentially print a plurality of slips per page on the obverse of the sheet according to sizes of slips, by selecting printing data for printing at least one slip on the obverse of the sheet out of the printing data received from a printing data transmitter, and also allows the first printer to print a mark representing a page-number of the each slip to be printed on the obverse of the sheet in a position thereof, wherein the second printer includes a mark reading sensor for reading the at least one mark printed by the first printer, and wherein the double-sided printing apparatus further comprises a second printing control unit which, upon receiving, from the first printing control unit, printing data including page-number information for printing at least one slip on the reverse of one page of the sheet as well as size information of at least one slip to be printed on the obverse of the same page, generates a reading timing signal for the mark reading sensor to read the at least one mark, and compares page-number information obtained by reading the at least one mark printed on the obverse of the one page of the sheet by using the mark reading sensor with page-number information included in the printing data for printing the at least one slip on the reverse received from the first printing control unit, so as to allow the second printer to print, on the reverse of the one page of the sheet, a slip having a page-number following the page-number of the last slip which has been printed on the obverse of the same page.