Xerox DocuColor 12/DCCS50, Service Manual

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10-65 DocuColor 12/DCCS50
DADF Operation
Principles of Operation
Reissue
Prefeed and Feed operation
The document Prefeed and Feed operation is activated when the Start Button is pressed. This
energizes the Feed Motor, which drives both the Nudger Roll and Feed Roll. The Nudger Roll
feeds the top document into the nip of the Feed Roll and the Retard Roll. The Feed Roll trans-
ports the document, one sheet at a time, into the DADF. The Feed Rolls work against friction
Retard Rolls to assure single feed operation.
Two-sided documents are routed through the DADF differently than single sided documents:
• For single sided documents , the new document sheet is not fed from the Input Tray
Assembly until the current document sheet passes and clears the DADF Registration
Sensor.
• For two-sided documents, the new document sheet is not fed from the Input Tray Assem-
bly until the current document sheet has been inverted through the DADF inverter path
and clears the DADF Registration Sensor a second time.
• For two-sided documents to be re-inverted, the new document sheet is not fed from the
Input Tray Assembly until the current document sheet has been sent through the DADF
inverter path a second time, and it passes and clears the Registration Sensor for a third
time.
Nudger Roll
When the Entrance Gate is in the up position, it holds the Nudger Roll up so that documents
can be loaded into the Input Tray. When the Start Button is pushed on the copier machine, the
Entrance Gate drops. This allows the Nudger Roll to drop onto the top copy of the documenta-
tion and feed a sheet into the nip of the Feed Roll and the Retard Roll. The Feed Motor drives
the Nudger Roll through a belt drive, and operate in one direction using internal one-way
clutches.
Feed Roll
The Feed Motor drives the Feed Rolls through a belt. The Feed Rolls rotate in only one direc-
tion, using a one-way internal clutch. The Feed Roll transports the document from the Input
Tray Assembly, past the Registration Sensor and into the nip of stationary Registration Rolls.
The Feed Motor deenergizes 50 msec after the Registration Senor senses the lead edge of the
document. The document being fed by the Feed Roll into the stationary Registration Rolls de-
skews the document.
Retard Roll
The Retard Roll is not motor driven. This roll uses internal one-way clutches to provide the
needed friction resistance for single sheet feed operation. A spring lever rests against surface
of the Retard Roll inside the mounting assembly. The lever rotates the Retard Roll a small
amount each time the Retard Roll is pushed down and released by a passing document. This
movement prevents uneven wear around the Retard Rolls. (verify!)
Registration System
The DADF Belt Motor drives the registration system. This bi-directional stepper motor uses a
belt drive to power the following rollers:
• Registration Roll (one-way clutch)
• Belt Roll (bi-directional)
• #1 Duplex Roll (one-way clutch)
• #2 Duplex Roll (one-way clutch)
The Belt Motor operates in one direction during document feed, registration, transport to the
Platen Glass and document exit. The Belt Motor reverses direction when inverting the docu-
ment.
There are two steps used in the DADF to register the document:
• The document is first de-skewed at the Registration Rollers.
• The document is registered on the Platen Glass by the Platen Belt.
Registration Roll and Registration Pinch Roll
The Belt Motor drives the Registration Roll through a belt. The Registration Roll uses a one-
way clutch and rotates forward only when the Belt Motor is rotating in the forward direction. The
Registration Roll creates a nip with the Registration Pinch Roll.
The Belt Motor is deenergized and the Registration Roll is stationary when the lead edge of the
document enters the registration nip. The Feed Motor continues to drive the document for 50
msec to de-skew the lead edge of the documentation against the Registration Roller nip. Then,
the Belt Motor turns the Registration Roll and transports the document to the Platen Belt.
Platen Belt and Belt Roll
The Belt Motor drives the Belt Roll through a belt. The Belt Roll moves the Platen Belt, trans-
porting the document onto and across the Platen Glass. The Belt Motor pulses for 51 counts
after the trailing edge of the document passes the Registration Sensor. This positions the doc-
ument onto the Platen Glass for copying.
For single sided documents: Immediately after the document has been scanned by the copier,
the Belt Motor energizes in the forward direction. This moves the copied document off the
Platen Glass and feeds the next document to be copied from the Registration Roll onto the
Platen Glass. Again, the Belt Motor pulses for 51 counts to register the second document to be
copied onto the Platen Glass.
For two sided documents: See Inverting Documentation
Inverting Documentation
The DADF can automatically turn over two sided documents to copy both sides.
Belt Motor Reversing
The DADF uses a bi-directional stepper Belt Motor to invert the documents. For two-sided doc-
ument handling, the Belt Motor first energizes in the forward direction (ccw when viewed from
the machine front) to feed the top, or side one, of the document onto the Platen Glass for copy-
ing. After side one has been copied, the Belt Motor reverses direction. This causes the Platen
Belt to run in reverse direction, transporting this original document from the Platen Glass into
the inverter path. See
Figure 3 concerning the assemblies driven by the Belt Motor in forward
and reverse directions.
The Lower and Upper Duplex Rollers are driven through one-way clutches. They activate only
when the Belt Motor is energized in the reverse (cw) direction. The Lower and Upper Duplex
Rolls turn over the document so that side two will face the Platen Glass for copying.