Xerox ColorQube 9303 Series Service Manual page 1748

Tray elevated in the up and
ready to feed position
Note: Retard roll and other parts of
SAR assembly not shown
Figure 3 SAR Feeders
A separation nip is formed by the nudger roll and a retard roll which is not shown. The nudger
roll is sprung and rests on the stack to feed the top sheet. If the stack is not within the feeding
position, the stack height sensor triggers the elevator to rise to the feeding position.
The SAR mechanism substantially reduces the incidence of multi-sheet feeding.
Because the speed of the sheet is slightly reduced by the effect of the retard roll, when the
leading edge reaches the paper feed sensor, the feeding speed is controlled to ensure the
sheet reaches the hand-over point in the IME within the allowable time window.
Paper Feed and Retard Rolls
Tray 5 feed roll / retard rolls are accessible from tray door access and by sliding the tray away
from the IME. The host controller monitors their usage, recording the sheet feed count in the
NVM, along with their life expectancy, to inform the customer service engineer (CSE) when
their end of life occurs.
Principles of Operation
Paper Present Detection
When the tray is less than 10% full, and the tray is in the up position, the software checks after
Nudger roll
each sheet feed for an 'out of paper' condition. The tray 5 empty sensor is a reflective type and
is situated directly over a hole in the paper tray, normally covered by paper. There will be no
reflection when the last sheet has been fed, and an 'out of paper' condition will be declared.
The GUI instructs the operator to refill the tray and further paper feeds will be inhibited. In a
normal tray 5 module, with A4 or 8.5 x 11 inch LEF stock and a door present, the tray is auto-
matically lowered. If there is no door, and a paper kit is installed, the tray is lowered when the
Stack height
manual push button is pressed and released. The out of paper status is raised to the host con-
sensor
troller. The tray will elevate again when the door is closed after refilling the tray.
Tray Height Sensor
Nudger roll
The machine keeps track of the tray height, based on the distance travelled from the start of lift.
A software height counter is zeroed when the tray starts to rise and the stack down sensor
goes low. As the tray rises, the elevator motor encoder sensor increments the height counter
for each pulse sensed from the vertical encoder track. When the tray reaches its upper posi-
tion, and the stack height sensor is actuated by the nudger roll, the value of the height counter
is passed to the IME, as a percentage of the tray 5 paper stock left on the tray. The IME holds
the stack height value as 0%, 5%, 10% and at 10% intervals up to 100% full, and this is avail-
Stack height
able for display to the remote web UI. The counter value is updated whenever the elevator
sensor
motor encoder sensor, changes state, and is saved to the NVM each time. If an expected
change in state of the height encoder does not occur, when the elevator motor is operating, a
fault condition is declared.
Stack Height when Feeding
The stack height sensor maintains the stack height by triggering activity of the elevator motor.
When a change in the condition of this sensor is detected, there is a de-bounce delay of 33
milli-seconds to allow the condition to settle, and if the change in the state of the sensor is con-
firmed, the elevator motor raises the tray, after the paper leading edge has passed the trans-
port rolls. The amount of movement is determined by the current position of the tray. This
position is used to read the 'motor-on time' from a look-up table, held within the machine.
Tray Overload
If the stack height sensor indicates the tray is at the feeding position, and at the same time the
stack down sensor detects the tray in the fully lowered position, the 'overloaded tray' status is
raised. The elevator motor movement is inhibited and an error is raised. This error condition is
maintained until the conditions producing it no longer apply.
Elevator Motor Stop
The elevator motor is never stopped by simply removing the power and allowing it to coast to a
stop. Whenever the motor is stopped, it is dynamically, actively braked to a stand still.
Elevator Upper and Lower Positions
The commonly used tray control sensors are:
• The stack height sensor
• The stack down sensor
• The paper empty sensor
• The elevator motor encoder sensor.
February 2013
8-54 ColorQube® 9303 Family