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3.3
Detection of Recording Paper Jams
A "recording paper jam" is a state where loaded recording paper has
jammed inside the unit without being picked up, fed or ejected. Recording
paper jams are detected by the ON/OFF timing of sensors that detect the
presence of recording paper. Generally, light-transmitting type photo-inter-
rupters which are a kind of optical sensor are used for detecting the pres-
ence of recording paper. When the light that is irradiated from the light-
emitting section of the photo-interrupter is detected by the light-receiving
section, the sensor turns "ON." Alternately, when light is blocked by the
actuator and cannot be detected by the light-receiving section, the sensor
turns "OFF." Changing of the ON/OFF state of the sensor in this way is
used for detecting the presence of recording paper.
Generally, the following four types of recording paper jams occur:
Light-emitting
section (LED)
Fig. 4-21 Photo-interrupter
• Pickup jam
• Feed jam
• Fixing unit wrap-around jam (only in case of LBP)
• Eject jam
RECORDING SECTION
Light-receiving section
(photo-transistor)
1
2
3
4
Actuator
5
6
ït
çi
4–19
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