Td Sensor Initialization - Ricoh B064 Service Manual

TD Sensor Initialization

The TD sensor must be initialized with SP2801 (TD Sensor Initial Setting) at the
following times:
• The first time the development unit is filled with developer
• Every time the developer is replaced.
The sensor control voltage is adjusted until the output is 3.0±0.1V. Then, after
setting the control voltage, Vt is sampled 100 times, these samplings are averaged,
then the average is used to set the standard value for Vt.
NOTE: 1) After developer is replaced, you must execute SP2801.
2) After the TD sensor is replaced, you must execute SP2801.
3) After a partially used development unit from another machine is
installed, you must use SP2220 (Vref Manual Setting) to enter the Vref
value for that unit, and use SP2906 001 (TD Sensor Control Voltage
Setting) to enter the TD sensor control voltage.
4) These initial values are stored in NVRAM. Before replacing the NVRAM,
print an SMC report so you can re-enter these settings manually after
the NVRAM is replaced.
Determining Vref
At certain intervals (see 'Sensor Control Mode, step 4), the ID sensor reads the
bare drum and the ID sensor pattern on the drum.
Vref is calculated from Vsp and Vsg as explained in the Process Control section of
the manual.
ID sensor pattern creation parameters depend on whether automatic process
control is switched on or off with SP3901 001 (Auto Process Control).
If automatic process control is switched on:
• Charge corona grid voltage: Set automatically for the existing conditions around
the drum.
• LD power: The value Vh is used to adjust the laser power. The laser diode writes
the Vh halftone pattern on the drum. The reading from this pattern is Vh.
• Development bias: The potential sensor checks the bias voltage when the ID
sensor pattern is created (target voltage: -230V) and boosts the voltage by –280,
the voltage set for SP2201 004 (ID Sensor Pattern Development Potential), to
bring the bias to the target voltage of –510.
If automatic process control is switched off:
• Charge corona grid voltage: Set to –800V, the default setting for SP2001 002 (ID
Sensor Pattern: Adj. to Applied Voltage).
• LD power: 185 µW (target drum potential –130V)
• Development bias: -360V, default for SP2201 002 (ID Sensor Pattern: Adj. to
Applied Voltage).
SM
DEVELOPMENT AND TONER SUPPLY
6-65 B064/B065