Disclosed is a printing system and more specifically, a scheduling system. This system finds particular application in conjunction with scheduling print jobs for improving the image consistency of adjacent images, such as those on facing pages and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
The eye is particularly sensitive to differences in appearance of printed images when faced with a side by side comparison. A print job assembled in the form of a booklet has several facing pages on which images are printed. Differences in color gamut, gloss, image size, and clarity are most perceptible on the facing pages. One way to minimize the differences in image appearance between the outputs of several printers is to run test patches on the printers and compare these with a reference, using a color sensor, such as a spectrophotometer. Since the output characteristics of a printer tend to vary over time, periodic recalibration is performed to maintain color consistency. Another approach is to print all of the pages on the same printer.
Parallel printing systems have or are now being developed which employ multiple marking engines working in parallel to improve the overall system output. Jobs are assembled from the outputs of several marking engines which may print with different gloss, color gamut, and image quality characteristics. For example, in a system employing two color marking engines, the first marking engine may print front and back pages of a first sheet and a third sheet, etc., in duplex mode and the second marking engine may print front and back pages of a second sheet and a fourth sheet, etc., in duplex mode. The streams from the two marking engines are subsequently merged to form a booklet. As a result, some pages of the assembled booklet are printed by the first printer and other pages are printed by the second printer. The eye is thus presented with two side by side pages which are printed by different printers.
Imaging systems (e.g., printers and copiers) typically include paper paths through which print media sheets (e.g., sheets of plain paper) which are to receive an image are conveyed and imaged. The process of inserting sheets into the paper paths and controlling the movement of the sheets through the paper paths to receive an image on one or both sides, is referred to as “scheduling.”
Electronic printing systems typically employ a print server or scanner for inputting image-bearing documents and conversion electronics for converting the image to image signals or pixels. In the case of electrophotographic printers, the signals are stored and are read out successively to a printer for formation of the images on photoconductive output media such as a photoreceptor. When multiple jobs are to be sequentially printed, a process known as “job streaming” is commonly implemented. Job streaming is the ability of a printer system to complete successive printing jobs with a minimum of delay time between jobs. A control system associated with the image output terminal of the machine identifies that multiple jobs have been scheduled, determines their characteristics and determines the necessary delay between jobs. In some cases, the control system will enable a second job to begin printing prior to completion of the first job.