Xerox DocuColor 12/DCCS50, Service Manual

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10-106 DocuColor 12/DCCS50
Paper Registration and Pre-Fuser Transport
Reissue
Principles of Operation
Paper Registration and Pre-Fuser Transport
The components and assemblies involved in paper registration accept a sheet of blank copy
material and ensure that its edges are absolutely parallel or perpendicular to the sheet’s direc-
tion of travel. This is done immediately before feeding the sheet to the IBT Belt.
Paper Registration and Paper Transport to the IBT Belt
The paper registration system uses a stalled-roll technique. As the blank copy material is being
transported by the Preregistration Rollers (from trays 1 through 4) or by the Tray 5 Take Away
Rollers, the lead edge of the media reaches the nip of the Registration Rollers. At that instant,
the Registration Rollers are not rotating. This forces the lead edge of copy into the nip, causing
the copy to buckle and making the lead edge parallel with the nip.
After a 100 to 140 ms delay, the Registration Motor begins turning the Registration Rollers,
moving the blank copy material to the nip between the IBT Belt and the 2nd Bias Transfer Roll.
The start of the developed image on the IBT Belt and the leading edge of the copy material
must be synchronized so that they meet. Therefore, the IOT Control and Drive PWBAs can
vary the speed of the Preregistration Rollers and the Dup Out Rollers from 360 mm/sec. to 540
mm/sec. This results from comparing the timing of the Preregistration Sensor signal caused by
the blank copy material’s leading edge with the timing signal from the TR0 Sensor on the IBT.
Any timing difference causes the speed of the Tray 5 Motor and Duplex Out Motor to be
adjusted.
After the copy material has been set to synchronize with the IBT and has been deskewed at the
Registration Rollers, it enters the nip of the Second Bias Transfer Roll (BTR) with the IBT Belt.
Refer to Xerographics for more information on the Xerographics process.
Paper Transport from the IBT Belt
A Vacuum Transport Belt carries the unfused print to the Fuser Subassembly. To maintain con-
sistent print transport speed during the Fusing process, the Fuser Motor transports the print
into, through and out of the Fuser Assembly. (See
Table 1 for Drive Motor information).
The vacuum that is used to hold the print to the belt comes from the Exhaust Blower Assembly
through the Xerographic and Vacuum Transport duct system. This means that the belt vacuum
may be diminished if the machine’s service doors are open.
The Fuser Entrance Sensor detects the lead edge for paper jams on the Vacuum Transport
Belt or from the IBT.
Refer to the Fuser Section for more information on this subassembly.
As the fused print exits the Fuser, the lead edge enters the Fuser Exit Roller nip. A Fuser Exit
Sensor detects the lead edge of the print as it leaves the Fuser Exit Rollers. If the lead edge is
more then 20 ms late, the Fuser will stop and a jam error code will be indicated.
Differentiating between paper and transparencies
Transparencies can only be fed from Tray 5. When transparency material is detected, the trans-
port speed for IBT, the Vacuum Transport, Fuser and Fuser Exit Rolls drops to its slowest
speed of approximately 60 mm/sec. When copy material is fed from Tray 5, two OHP Sensors
examine the edges of the material to determine if the material is opaque on that edge through
its whole length. The outputs of these sensors are routed to the IOT Drive and Control PWBAs
for processing.
The OHP Senors are a LED transmitted-light-detection type. Since paper is opaque, it blocks
light from the sensors’ LEDs to their photoreceptors. This isn’t the case with transparency
material, except for a short interval when either or both sensors encounter the opaque white
strip on some transparency material.
When the Registration Sensor detects the lead edge of the copy material, the signal from both
OHP Senors is also read. If the material is paper, then these sensors are blocked. If the trans-
parency material is fed with the white strip (5 mm in width) first, then the OHP Sensors are also
blocked. Readings from the OHP Sensors are taken at 0.1 second intervals. If the LED of the
sensors are detected, this indicates the material is a transparency that is being transported.
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