Ros Control; Scanner Motor Operation; Ros Warm-Up; Quantity Of Light Control - Epson AcuLaser C8500 Service Manual

EPSON AcuLaser C8500

2.7.5 ROS Control

2.7.5.1 Scanner Motor Operation

The Scanner Motor is turned ON/OFF as follows for each mode:
Table 2-4. Scanner Motor Operation
Operation mode
WARM UP mode
READ mode
PRINTING mode
DEEP SLEEP mode
LIGHT SLEEP mode
NOTE: The Scanner Motor runs when diagnostics tool "Printing/Status
Control" / "PMSTT" is executed, regardless of the above.

2.7.5.2 ROS Warm-Up

The Scanner Motor starts running at the same time ROS warm-up begins. If the
Scanner Motor is running at a constant speed the SO signal interval is shorter
than the READY reference value. ROS warm-up is over when the SOS signal
interval is shorter than the READY reference value 3 times consecutively after
ROS warm-up starts.

2.7.5.3 Quantity of Light Control

Image data is input to the ROS (LD Assy) as an electric signal (expresses
image data according to differential signal), and the LD Assy converts the
image data from an electric signal to an optical signal (expresses data by
flashing the laser beam on and off). If there is disparity in quantity of laser light
(LD Power), the optical system (lens, etc.), or sensitivity of the drum, the proper
electrostatic latent image cannot be obtained. The LD Assy therefore monitors
and controls quantity of laser light based on feedback of potential control (see
2.7.6.1 "Potential Control" in this chapter) so a stable, proper electrostatic
latent image can be obtained. This is called "APC (Automatic Power Control)."
Operating Principles
Scanner Motor ON/OFF
OFF
OFF
ON
OFF
OFF
APC EXECUTION TIMING
1) Prior to printing (print job).
2) When VREF signal (reference voltage corresponding to target values for
quantity of light) is changed by potential control (when target values for
quantity of light are altered).
3) Each line by timing of SOS light signal (internal signal to output laser
radiation due to SOS signal) while printing.
APC PROCEDURE
When APC execution timing is 1, 2.
1) VREF signal is set (by potential control feedback).
2) LD ENB signal is set to Low. (Permits emission of laser radiation.)
3) The different movement voltage at the VDATA signal /nVDATA sign
is set to High. (Turns laser radiation on.)
4) PCONT signal is set to Low. (Adjusts quantity of laser radiation so that
the quantity monitored is equal to the VREF signal.
5) PCONT signal is set to high and the different movement voltage at the
VDATA signal /nVDATA signal is set to Low. (APC complete)
When APC execution timing is 3.
1) The different movement voltage at the VDATA signal /nVDATA signal is
set to High and PCONT signal are set to Low prior to SOS on signal.
(Adjusts quantity of laser radiation so that the quantity monitored is equal
to the VREF signal.
2) SOS signal is detected.
3) PCONT signal is set to high and the different movement voltage at the
VDATA signal /nVDATA signal is set to Low. (APC complete)
Revision C
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