Lexmark T652 Service Manual - Page 298

4062-XXX Media level sensing The media level for the media tray assembly is triggered by the actuator flag positioned in the two photointerrupter sensors in the pick arm bracket assembly. The actuator flag blocks and unblocks the two sensors in different sequence; it determines whether the paper tray is empty, low, or full. 250-sheet tray Tray full Tray low Tray empty Sensor A unblocked blocked blocked Sensor B unblocked unblocked blocked 550-sheet tray Tray full Tray low Tray empty Sensor A unblocked blocked blocked Sensor B blocked blocked unblocked Note: Media level sensing through sensor blocking sequence Pick arm assembly Sensor (media empty) Media out actuator Sensor (media low) Pick roll assemblies Since all media trays are functionally equivalent in terms of the switch (media size), sensor (media empty), sensor (media low), only the components of one tray are described here. The pick arm assembly is a mechanical unit supplying media from the media tray assembly to the printer. The driving force, from the pick arm drive motor on the pick arm assembly, is transmitted to the two pick rolls to feed media. When the pick rolls pick up media, the remaining media decreases, and the media out actuator will lower and interact with the sensor (media low) and sensor (media empty) to determine the amount of media remaining. 3-86 Service Manual