Ricoh DD 5450, Field Service Manual, Page: 139 / 403

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Chapter 3 Paper Feed Section
CN11-28
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(5) Paper Sensor
Description
The paper sensor is located at a fixed distance relative to the paper; as the paper is being fed, the
paper sensor detects presence/absence of paper by means of intensity of reflected light.
When the paper in the tray runs out, the message "NO PAPER" is displayed and printing stops.
Circuit
Operation
When there is no paper, the sensor does not detect the reflected light, so it is 5V.
When paper is placed inside, the sensor detects the reflected light, so it is 0V.
● When absence of paper is detected, master making, printing and test printing can not be
performed.
● If paper runs out during printing, "NO PAPER" is displayed on the LCD panel, printing is stopped,
and the feed tray descends to its lower limit position.
● If paper runs out during master making, operation continues until the end of the master making
process, then operation stops (without proceeding to the printing process), and the feed tray
descends to its lower limit position.
Paper sensor
Paper presence: Reflected light (0V)
No paper: No reflected light (5V)
Main PCB unit
Reflected light : 0V
No reflection light : 5V
● Paper presence: ● No paper:
Paper sensor
Reflected light
Paper
No reflected light
Blue Blue
White White
Red Red
Blue
White
Red
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