HP LaserJet 3052 Service Manual - Page 110

Scanner operation, ADF operation, Standby paper-loading mode

Page 110 highlights

The image data CCD sensor uses a 300 ppi array and two half-pixel-offset 600 ppi arrays which are capable of collecting data at 600 ppi or 1200 ppi (600 ppi if one array is used or 1200 ppi if both arrays are used). Scanner operation At startup and periodically at other times, the scanner assembly moves systematically to locate its home position. It then calibrates to a white strip located under the glass at the right end of the scan tub. If the all-in-one detects a document in the ADF when a copy or scan is initiated (from the software or the control panel), the scan module moves to the left side of the scan tub and stops. The image is acquired as the paper is fed through the ADF past the scanner module. If no document is detected in the ADF, or if the model does not have an ADF, the scan module acquires the image from the flatbed glass while slowly moving within the scan tub. ADF operation Standby (paper-loading) mode: In standby mode, the pickup roller is up and the stack-stop is down, preventing the user from inserting the original document too far. When a document is inserted correctly, the paper-present sensor detects its presence. The standard operation of the ADF consists of the pick, feed, and lift steps. Pick: When it receives a copy or scan command, the ADF motor engages the gear train to lower the pickup-roller assembly and raise the stack-stop. The first roller, called the pre-pick roller, moves the top few sheets forward into the ADF. The next roller is the pickup roller. This roller contacts the ADF separation pad, which separates multiple pages into single sheets. Feed: The single sheet continues through the path. Along the way, the form sensor, which is a set distance from the ADF glass, detects the sheet. This alerts the scanner to start when the page reaches the glass. The scanner acquires the image, one raster line at a time, until it detects the end of the page. The page is then ejected. The pick and feed steps are repeated as long as paper is detected in the ADF input tray. Lift: When no more paper is detected in the ADF input tray and the form sensor detects the trailing edge of the last page, the last sheet is ejected and the motor turns in a sequence that lifts the pick roller assembly to standby (paper-loading) mode again. The ADF will not function when the ADF lid is open. The paper path is incomplete if the ADF lid is lifted from the glass. 90 Chapter 4 Theory of operation ENWW

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The image data CCD sensor uses a 300 ppi array and two half-pixel-offset 600 ppi arrays which are
capable of collecting data at 600 ppi or 1200 ppi (600 ppi if one array is used or 1200 ppi if both arrays
are used).
Scanner operation
At startup and periodically at other times, the scanner assembly moves systematically to locate its home
position. It then calibrates to a white strip located under the glass at the right end of the scan tub.
If the all-in-one detects a document in the ADF when a copy or scan is initiated (from the software or
the control panel), the scan module moves to the left side of the scan tub and stops. The image is
acquired as the paper is fed through the ADF past the scanner module.
If no document is detected in the ADF, or if the model does not have an ADF, the scan module acquires
the image from the flatbed glass while slowly moving within the scan tub.
ADF operation
Standby (paper-loading) mode:
In standby mode, the pickup roller is up and the stack-stop is down,
preventing the user from inserting the original document too far. When a document is inserted correctly,
the paper-present sensor detects its presence.
The standard operation of the ADF consists of the pick, feed, and lift steps.
Pick:
When it receives a copy or scan command, the ADF motor engages the gear train to lower the
pickup-roller assembly and raise the stack-stop. The first roller, called the pre-pick roller, moves the top
few sheets forward into the ADF. The next roller is the pickup roller. This roller contacts the ADF
separation pad, which separates multiple pages into single sheets.
Feed:
The single sheet continues through the path. Along the way, the form sensor, which is a set
distance from the ADF glass, detects the sheet. This alerts the scanner to start when the page reaches
the glass. The scanner acquires the image, one raster line at a time, until it detects the end of the page.
The page is then ejected. The pick and feed steps are repeated as long as paper is detected in the ADF
input tray.
Lift:
When no more paper is detected in the ADF input tray and the form sensor detects the trailing edge
of the last page, the last sheet is ejected and the motor turns in a sequence that lifts the pick roller
assembly to standby (paper-loading) mode again.
The ADF will not function when the ADF lid is open. The paper path is incomplete if the ADF lid is lifted
from the glass.
90
Chapter 4
Theory of operation
ENWW