Xerox DocuColor 12/DCCS50, Service Manual

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10-44 DocuColor 12/DCCS50
Copier Timing
Reissue
Principles of Operation
Copier Timing
The main machine timing signal is the Transfer Roll Zero (TR0) Signal. This signal is used to
synchronize the various steps of the process to correctly position the image on the output
media. TR0 is produced when the leading edge of a timing strip across the Intermediate Belt
Transfer (IBT) Belt passes over the TR0 sensor.
The IBT has two timing patches which are separated by one-half of the IBT circumference.
Since the IBT has a circumference of the IBT is 527.81 mm, this means that the two timing
patches are 263.905 mm apart. Therefore, an 8-1/2” x 11” or A4 sheet (or smaller) will fit LEF
on the IBT between the timing patches and two sheets will fit on the entire IBT. An 11” x 17,”
12”x18” or A3 sheet will fit SEF on the entire IBT, across one of the patches.
In addition, the Drum Motor includes an encoder which outputs one pulse per revolution to the
IOT Drive and Control PWBAs. This is used for motor speed control rather than as a paper
transport timing reference. The Interval between TR0 pulses and the frequency of the Drum
Motor output pulses depends on the process speed. The process speed depends, in turn, on
the type of media being used for the copies. The following Table shows the correlation between
these three factors.
Transparency material must be inserted in Tray 5 and can be detected automatically. For other
media, the user must manually enter its weight at the start of a job. Therefore, the machine
knows the paper copy weight of the start of a job and adjusts the process speed accordingly.
The default value is paper less than 105 gsm or 28 lb. Therefore, the default process speed is
220 mm/sec.
Table 1 Copy Input Media, Process Speed and TR0 Interval
Input Media Process Speed
Motor Clock
Pulse Frequency TR0 Interval
Extra Heavy Weight
164-250 gsm paper
90-140 lb index
90 lb cover
Transparencies 59.82 mm/sec 544.0 Hz 4.412 sec
Heavy Weight
106-163 gsm paper
28-90 lb index 129.68 mm/sec 1179.4 Hz 2.035 sec
Normal
less than 105 gsm paper
less than 28 lb index 219.47 mm/sec 1996.0 Hz 1.202 sec
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