Carriage

Description | Theory of Operation

Description

Carries the exposure head along the length of the drum.

Theory of Operation

The ALE board (10-3691) is the control center for the ThermoFlex carriage drive system. It contains a carriage step synthesizer which controls the speed and position of the carriage at all times.

Carriage motion during plotting

Carriage motion is synchronized to image data output. From the home position, the ballscrew moves the exposure head at a programmable speed until imaging is finished.

If the workstation is unable to deliver raster data at the recorder imaging speed, the carriage drive switches to asynchronous mode. The carriage stops, reverses and waits at a retrace position until the DPE buffers have filled with data. At this time, the carriage accelerates to speed in time for the next image rotation.

Carriage position

Carriage position and velocity are locked to drum speed through the stepper synthesizer and digital PLL on the MPE board (10-3692). This is an open loop system as there is no encoder on the carriage sub-system. Therefore, for the head position information to be accurate, the carriage cannot drag or stall.