Patent Application
20080279569
The present disclosure relates to printing of digital images and particularly printing by an electrostatic or xerographic process in which an image is generated on a photoreceptor and transferred to a print media sheet and heat fixed thereon. More particularly, the disclosure relates to duplex printing of digital images by the electrostatic processor printing on both sides of the print media sheet.
With the advent of electrostatic photocopiers capable of relatively high production rates, these machines have found particular suitability to printing of documents requiring duplex printing where the individual sheets or pages are subsequently bound into books or pamphlets and the like. However, in duplex printing of sheets or pages intended for binding, in order to provide a quality print job which is competitive in the market place, it is necessary that the print on both sides of the pages be registered or positioned on the page such that there is no noticeable variation to the reader of the print on the page from the first to the second side. It has been found that variations of 2 mm or less in the image registration from Side 1 to Side 2 of a sheet or page are quite noticeable to the eye of the reader and give the impression of a poor quality print job. Accordingly, it has been found necessary to maintain very tight control of the image magnification or registration in duplex printing from Side 1 to Side 2, or front to back, of the printed media sheet.
Maintaining the aforesaid tight control of print magnification from Side 1 to Side 2 in a duplex printing job on an electrostatic photocopier has proven to be difficult and costly in such machines set up for high speed duplex printing. This has been found to be the case irrespective of whether the digital image is transferred directly to the electrostatic printing machine such as from a computer or is generated from a printed sheet inputted for copying and reproduction. The complexity of the processes within the electrostatic print engine including the transport of the paper through the sheet path and heat fusing in the print engine has introduced error in the print magnification and registration from Side 1 to Side 2 on a printed sheet.
Accordingly, it has been desired to provide a way or means of enabling the user to control the quality of the duplex printing with respect to the image magnification and registration on the printed sheet; and, particularly it has been desired to provide the user with a way or means of correcting errors in the print magnification by varying the printing process.
The present disclosure describes a method of enabling the user to adjust the printing process in an electrostatic printer to correct errors of print magnification and registration in duplex printing for maintaining the quality of the print job and particularly for controlling print magnification such that the reader of the printed document will not notice variation in the magnification or registration of the images printed on Side 1 and Side 2 of the printed sheet or page.
The presently described and illustrated method provides a user input panel or interface on an electrostatic reproducing machine upon which the user may enter commands for incrementally changing the longitudinal and lateral magnification of the digital image prior to printing. The user is enabled to determine the desired amount of correction for the print magnification by running a test print and measuring the variation of the print magnification and registration from Side 1 to Side 2, or front to back, of a printed sheet. The percentage change from front to back is then computed; and, the user can input a desired number of predetermined incrementally small changes in the percentage of magnification and view the results on another test print. Once the test prints confirm that the correct preprint magnification corrections have been made to the digital image, the print job may be run in its entirety.
In one embodiment of the method described in the present disclosure, the user inputs the desired corrections for print magnification by analog controls such as, for example, rotating control knobs to a position indicated for the desired amount of correction. In another embodiment of the method described and disclosed herein, the user input panel provides touch screen digital entry of desired amounts of print magnification correction. The method of the present disclosure is described in an exemplary embodiment wherein the user desired corrections are inputted to the digital front end (DFE) or controller for changing the operation of a raster image processor (RIP) prior to printing on the respective Side 1 and Side 2 of the sheet.
a is a section view taken along section indicating lines 2-2 of
b is a view similar to
Referring to
The machine 10 includes a user input panel or console indicated generally at 42 which has provision thereon for manually inputting, to the digital controller or DFE 15 for the machine, desired corrections to the print magnification which controls the raster image processor 16.
Referring to
At step 52, a new duplex printed test sheet is made and at step 54 the print magnification on Side 1 and Side 2 is measured and the percentage difference in magnification computed by the user. At step 56, a determination is made by the user as to whether the print magnification Side 1 to Side 2 is within acceptable limits; and, if the determination is affirmative the print job is run at step 58.
However, if the determination at step 56 is negative, then it is necessary to return to step 46 and measure the Side 1 and Side 2 magnification and input a new set of corrections to the user interface 42.
Referring to
User input panel or console 60 also includes separate indicator windows for indicating the selected percentage change of the lateral and longitudinal print magnification for Side 2 of the printed sheet; and, these are denoted respectively by reference numerals 72, 74 in
Referring to
Console 84 has a second knob 86 disposed below knob 84 for user rotation to provide incremental and decremental changes in the percent of longitudinal print magnification by amounts of 0.01 percent for each position of the knob rotation. The clockwise rotation of the knob 86 provides increments of 0.01 percentage change and counterclockwise rotation of the knob 86 providing decremental changes of 0.01 percent of longitudinal print magnification.
Adjacent the right hand side of the console 84 in laterally spaced arrangement is disposed a pair of knobs denoted 88, 90 arranged one under the other for user inputting corrections for print magnification in the printing of Side 2 of the duplex printed sheet. The upper knob 88 is rotatable clockwise for incrementing the lateral print magnification of Side 2 by 0.01 percent for each indicated position of the knob; and, knob 88 is rotatable counterclockwise for decrementing the lateral print magnification by 0.01 percent by each of the rotary positions indicated.
The lower knob 90 is similarly rotatable clockwise for incrementing by 0.01 percent, for each rotary position indicated, the longitudinal print magnification of side 2 of the duplex printed sheet. Counter clockwise rotation of knob 90 provides decrementing of 0.01 percent of longitudinal print magnification for Side 2 of the duplex printed sheet.
Referring to
The present invention thus provides a method of duplex printing in an electrostatic or xerographic printer with a user interface which permits entering corrections to the print magnification both laterally and longitudinally for Side 1 and Side 2 of the printed sheet based upon the user's measurements from a test print of the print magnification produced by the existing settings of the machine.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
