Patent ID: 7004653

Claim:
A printer comprising: image read means for reading out image data in each of printing papers; data storage means for storing said image data thus read out; image print means for printing said image data thus stored; operation setting means for setting operation conditions of printing; display means for displaying the operation state of said printer and the specified operation conditions; and print process means for executing processes required to print said image data in accordance with a predetermined program, wherein at least two pairs of printing papers, each paper having a printed content on one side and a blank page on the other side, are used, wherein, based upon an instruction of the two-set double-sided printing which is specified by said operation setting means, said print process means allocates each of said image data read out by said image read means to the corresponding sheet number, 1, 2, . . . , n−3, n−2, n−1, n of each printing paper, and determines the total number n of said printing papers by counting the sheet number, wherein in the case when the total number n of printing papers is even, an even-number-sheet printing control process is carried out, where image data for 2, 1, . . . , n−2, n−3, n, n−1-th printing paper are sequentially fed to said image print means, and printing papers, each of which is placed on a paper feed tray for printing in such a manner that its blank page on the other side is printable, are received in the order of reading by said image print means, whereby image data fed from said print process means are sequentially printed on the other side of the corresponding printing papers, so that a two-set double-sided printing is carried out; and wherein in the case when the total number n of printing papers is odd, an odd-number-sheet printing control process is carried out, where image data for 2, 1, . . . , n−3, n−4, n−1, n−2-th printing paper are sequentially fed to said image print means and finally said image data for n-th printing paper is fed to said image print means, and printing papers, each of which is placed on the paper feed tray for printing in such a manner that its blank page on the other side is printable, are received in the order of reading by said image print means and finally a supplementary paper sheet having blank pages on both sides is received, whereby image data for 2, 1, . . . , n−3, n−4, n−1, n−2-th printing paper fed from said print process means are sequentially printed on the other side of the corresponding printing papers and the image data for the n-th printing paper is forbidden to print on one side of the n-th printing paper, but printed on one side of the supplementary paper sheet, so that the two-set double-sided printing is carried out.