Advancing the Media
MediaDrive Mechanics
The media is advanced by the media drive (X9drive) system. Components include:
DMedia motor (X9axis motor)
DWorm pinion and helical drive9roller gear
DDrive roller
(Illustration ' page 10923.)
The main component of the drive system is a full9width, 6.49cm (2.59inch) diameter roller with an elastomer skin. This roller directly drives the media and provides the surface that references the media to the print9head.
The media9motor position control uses an encoder feedback loop. The encoder wheel is mounted to the motor shaft, and the optical reader is mounted inside a bell housing attached to the back of the motor.
MediaDrive Accuracy
The main purpose of the media drive system is to accurately move media such that the alignment of adjacent print swaths is of high enough precision that the plotter specifications are met and print quality is maintained. The media9drive accuracy (end9point accuracy, or X9axis accuracy) specifies how accurately a plotter can draw a line of a given length. (Specifications ' chapter 1.)
The configuration plot draws cross9hairs 500mm apart that you can use to measure the plotter's accuracy. (Details ' chapter 7, w Accuracy Calibration.)
Contributors to the Accuracy
All the above components of the media drive system contribute to the media9drive accuracy. The following also contribute:
DRadius variations produced by the way the media wraps around the drive roller, and the way the pinch9wheels and star9wheels maintain this radius
DErrors in the media motor's optical9encoder feedback system (this system gives feedback to the motor9control circuitry)
Dimensional changes in the media will affect lines drawn in both axes either during plotting or after the plot is drawn. For this reason, media other than polyester film does not support the media9drive accuracy specification. Polyester film is the only media that maintains dimensional stability to within the plotter specification ranges.
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