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BUFFERED OUTPUT FOR TWO PASS - TWO COLOR PRINTING MACHINES

IP.com Disclosure Number: IPCOM000026904D
Original Publication Date: 1994-Apr-30
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 228K

Publishing Venue

Xerox Disclosure Journal

Abstract

Two pass - two color or highlight color printing machine 5 shown in Figure 1 is inefficient when operating in two color mode, since a number of skipped or unproductive pitches can occur when operating in this mode. In two color mode, a sheet cycles back to transfer area 6 after a first color (or black) image is transferred to the sheet. During the time it takes to cycle a sheet back, which is on the order of three pitches, printing machine 5 cannot be imaging other black only copies. For example, given a print job sequence where three sheets require, black only, black plus color and black only: the first sheet is imaged and sent to output tray 19; the second sheet is imaged in black and then sent back to transfer station 6 for highlight color imaging; and the third sheet is not imaged until the second sheet has completed. Thus, given return path 7 is three pitches long (i.e. capable of holding three sheets), a total of seven pitches would be required to transfer four images on three sheets.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

BUFFERED OUTPUT FOR TWO PASS -TWO COLOR PRINTING MACHINES Int. C1. G03g 15/00 Thomas Acquaviva
Cyril
G. Edmunds

Proposed Classification

U.S. C1.355/319

FIG. I

XEROX DISCLOSURE JOURNAL - 1701.19, No. 2 March/April 1994 161

[This page contains 1 picture or other non-text object]

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BUFFERED OUTPUT FOR TWO PASS - TWO COLOR PRINTING MACHINES(cont'd)

FIG. 2

162 XEROX DISCLOSURE JOURNAL - Vol. 19, No. 2 March/April 1994

[This page contains 1 picture or other non-text object]

Page 3 of 4

BUFFERED OUTPUT FOR TWO PASS - TWO COLOR PRINTING MACHINES(Cont'd)

Two pass - two color or highlight color printing machine 5 shown in Figure 1 is inefficient when operating in two color mode, since a number of skipped or unproductive pitches can occur when operating in this mode. In two color mode, a sheet cycles back to transfer area 6 after a first color (or black) image is transferred to the sheet. During the time it takes to cycle a sheet back, which is on the order of three pitches, printing machine 5 cannot be imaging other black only copies. For example, given a print job sequence where three sheets require, black only, black plus color and black only: the first sheet is imaged and sent to output tray 19; the second sheet is imaged in black and then sent back to transfer station 6 for highlight color imaging; and the third sheet is not imaged until the second sheet has completed. Thus, given return path 7 is three pitches long (i.e. capable of holding three sheets), a total of seven pitches would be required to transfer four images on three sheets.

Disclosed is a method and apparatus for increasing the productivity of two pass - two color (highlight) printing machines. Figure 2 shows the improved printing machine 10, with an additional top stacking and bottom feeding high speed buffer tray 15, which is positioned off of pre fuser transport 17. Alternatively, shunt path 16 (shown using dotted lines) can be used to buffer sheets. Using buffer tray 15, sheets are deflected into tray 15 or permitted to go directly through to copy output tray 19. Sheets fed out of high speed buffer tray 15 are eventually fed from tray 15 to output tray 19 depending on the order that sheets should take in output tray 19. Printer 10 realizes increased productivity by using controller 20 to alter the order in which sheets are sequentially printed to minimize the occurrence of skipped pitches, and by using buffer tray 15 to reorder sheets that are not sequentially printed for productivity reasons.

As an example, a ten page print job is copied and pages eight, four and three have highlight color images (designated by "B&C") and the other pages have only black images (designated by "B").

Printing machine 5 shown in Figure 1 would print the job as follow with skipped pitches (designated by =XI'):

10B,9B,8B,X,X,X,8c,7B,6B,5B,4B,3B,X,X,4C,3C,2B71B. [21

Thus using printer 5, after sheet 8 is copied in black (8B), three skipped pitches result be...