Xerox WORKCENTRE 3119 Service Manual page 135

Air Temperature Sensor
N/A
Environment Recognition
Several reference voltages are supplied to the transfer roller to determine the environment. First,
it supplies a low voltage to the transfer roller and then when a fixed time has elapsed, it reads the
resistance value of the transfer roller by means of the ADC unit. It operates until the value is lower
than a specific value. If the resistance value of the transfer roller is lower than the specified value,
it then decides an array index for the voltage and then searches an appropriate index in the table
presented by the developer team.
Functional Requirements of HVPS Control
The engine supplies the developer unit with high voltage through the HVPS unit in order to form
an image on the paper fed through the paper path. So the engine-control firmware supplies the
high voltage to the developer unit at the specified time and position of the paper during the printing
process.
The HVPS unit is controlled by the PWM. The output voltage is determined by the PWM duty. For
reference, the PWM cycle is about 14 KHz presented by the power team.
There are 3 kinds of high-voltages as follows:
MHV
This high-voltage is supplied to the OPC drum through the charging roller while charging the skin
of the OPC drum
with a minus voltage.
THV
• THV +
The (+) transfer high voltage is supplied to the transfer roller for transfering toner onto the OPC
drum to the paper. This is determined by the environmental index.
• THV -
The (-) transfer high voltage is supplied to the transfer roller to remove the remaining toner from
the OPC drum. The value is fixed to about -1000V.
DEV
This high-voltage is supplied to the developer roller to transfer the toner to the charge on the OPC
drum scanned by the laser beam while printing the image. The engine controls whether the high
voltage is supplied and its quantity. The developer team presents the timing chart to control the
high voltage.
Functional Requirements of Power Save Mode
The power save mode is controlled by the main system firmware. In order to switch the ready state
to the power save mode after a specified time, the main system sends a sleep command to the
engine. When the engine receives a sleep command, it stops the operation of the fuser and the
fan unit in the engine. The main system then sets the engine to a sleep state. A user can select
WorkCentre 3119
General Procedures and Information
06/06 6-25