Operations/Functions; Sensor Sensitivity Adjustment; Paper Top Edge Detection; Checking Paper Cut - Epson Stylus Pro 4400 Service Manual

EPSON Stylus Pro 4400/4450/4800/4880/4880C

2.2.7.2 Operations/Functions

SENSOR SENSITIVITY ADJUSTMENT

Before performing any function/adjustment, the sensor sensitivity level must be
set for use as a standard.
Specifically, paper gets fed and the LED light emission quantity should be
adjusted to 3V that refers to the difference of the sensor output voltages that
have been received between over the paper and over the no paper position
(over the platen position). If the required light quantity is not obtained during
adjustment of PW1 and PW2, a printer error occurs.

PAPER TOP EDGE DETECTION

Top Edge Detection
When paper is fed, the paper and platen are continuously scanned and the
point at which the obtained reflection light level changes is detected as the top
edge of the paper. As a detection operation, this detects the approximate top
edge of the paper and confirms that it is within the range of required
specifications when the paper is fed. If the paper top edge is not within the
required range at this time, a paper feed error occurs. After that, the top edge
of the paper is detected. The same type of detection operation is performed on
both the column 1 side and the column 80 side.
When paper is fed, the Carriage Unit moves to the specified position at the
column 1 side and goes to standby over the paper. The sensor LED emits light,
the paper is reverse fed at 40CPS from the condition being detected for the
paper, and then the position at which the platen is detected is set as the
approximate top edge of the paper. Next, the paper is forward fed at 5CPS
from the condition at which the sensor is detecting the platen, and this detects
the paper top edge.
The process continues by detecting the top edge of the paper in the same way
at the column 80 side. The top edge position detected at column 1 is compared
with the top edge position detected at column 80, and the top edge detected at
the rear (as seen from the eject direction) is set as the paper top edge in order
to prevent printing to platen. For this reason, after the paper top edge is
detected at column 1 side, if paper is detected at the position when the
Carriage Unit moves to column 80 side, the position detected at the column 1
side is set as the top edge of the paper without performing the detection
operation at the column 80 side.
Operating Principles
Detection
Position
Detected as the paper top edge

Checking Paper Cut

Detects cut condition of paper.
After paper is cut, the paper top edge is continuously scanned from the paper
right edge to the paper center, the entire scanned area is passed over, and if
platen surface level output is detected it is determined that the paper has been
cut. If paper is detected at any part, a paper cut error occurs.
Printer Mechanism Components
Paper
Figure 2-50. Top Edge Detection
Paper
Detection
Position
Figure 2-51. Checking Paper Cut
Revision C
Feed
Direction
Detection
Position
Feed
Direction
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