When the leading edge of the paper activates the
input/registration sensor (PS1), the DC controller forces the laser
diode ON until a BD signal is received. Next, the DC controller
receives a VIDEO data stream (VDO) from the formatter. The
DC controller translates the VDO data into a VIDEO OUT signal
(VDOUT), which modulates the laser diode ON and OFF, creating
intermittent bursts of laser light which reflect off the scanner
mirror and onto the photosensitive drum to form a latent
electrostatic image. VDO data is sent from the formatter for each
scan line of print data on a page, and a BD signal must precede
each VDOUT line data received by the DC controller.
When the paper exit sensor (PS3) is activated by the leading edge
of the first page, the DC controller allows the Fusing Roller to
warmup to 183° C. After the last VDO data is sent for the last
line of print data on the first page, the formatter sends a PRNT
signal for the second page.
About 1.87 seconds after the first VDO signal is sent from the
formatter, the High Voltage PCA applies positive high voltage to
the transfer roller.
When the DC controller identifies the last line of print data on
the first page, the laser diode is forced ON and generates a sweep
beam used to adjust the laser power. After the DC controller
receives a BEAM DETECT signal (BD) initiated by the sweep
beam, the laser power stabilizes and the sweep beam turns OFF.
The DC controller then searches for a PRNT signal to begin the
When the DC controller receives the next PRNT signal from the
formatter, the DC controller anticipates receiving a BD signal
and energizes the pickup roller clutch solenoid (PC tray-SL1, MP
tray-SL2, or lower cassette SL3) about 1.0 second before it
receives the BD signal, and the second page feeds from the paper
tray. Until the DC controller receives the expected BD signal, a
nominal positive voltage is applied to the transfer roller to
prevent toner build-up while the transfer Roller is in direct
contact with the drum.
5-40 Functional Overview