Pre-Feed; Pre-Registration - Lexmark X940e Service Manual

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Pre-feed

In the pre-feed step, a document sheet is fed from the Feed roll to the ADF transport roll assembly. To correct
the skew, side1 of the document sheet is thrust against the ADF transport roll assembly rotating in the reverse
direction, and side2 is thrust against the ADF transport roll assembly at rest.
With the pick roll at the down position (see Preparation for feed), the ADF feed motor assembly rotates in the
reverse direction (CCW direction) to drive the pick roll and Feed roll. The pick roll feeds the top document sheet
on the document tray toward the Feed roll. The Feed roll nipped by the separation roll feeds the document
sheets (from the pick roll) one by one. When the sensor (ADF sheet through) detects a document sheet, the
machine recognizes that feed of the first document sheet is complete.
When the sensor (ADF pre-registration) detects a document sheet, the ADF feed motor assembly slows down.
As a result, the document sheet stops against the ADF transport roll assembly, correcting the skew.
ADF transport roll assembly

Pre-registration

In the pre-registration step, the document sheet (fed to the ADF transport roll assembly in the pre-feed step) is
fed to the ADF registration roll assembly, and then the lead edge of the document sheet is fed from the ADF
registration roll assembly, to the scan feed reference position (Wait Position) located upstream from the scan
position, where the document stops. Thus, registration of the lead edge of the document is performed.
When the document sheet is fed to the ADF transport roll assembly, the ADF feed motor assembly changes its
rotational direction to the normal direction (CW direction) to drive the ADF transport roll assembly. The ADF
transport roll assembly feeds the document sheet toward the ADF registration roll assembly. When the sensor
(ADF pre-registration) detects the document sheet, the ADF registration motor rotates in the reverse direction
(CCW direction) to drive the ADF registration roll assembly, ADF feed-out roll assembly, and ADF exit roll
assembly. The ADF registration roll assembly feeds the document sheet (fed from the ADF transport roll
assembly) to the scan feed reference position.
When the sensor (ADF registration) detects the document sheet, the ADF feed motor assembly slows down.
From this moment on, the ADF feed motor assembly and ADF registration motor decelerate continuously until
the document stops in the predetermined amount of time. At this point, the document sheet stops with the lead
edge nipped by the ADF registration roll assembly at 15 mm from the top. This is when the document sheet
stops at the scan feed reference position.
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Service Manual
Feed roll