Olivetti d-Color MF4003 Service Manual page 606

d-Color MF4003/MF3303
• Resistance of the 2nd transfer roller changes with an environmental change, durability, and other factors. To maintain an optimum output
voltage, fixed current is passed through the 2nd transfer roller and the voltage being outputted at that time is detected. An appropriate
2nd transfer voltage is determined based on the measured voltage and other information such as "type of paper used", "temperature and
humidity", "color mode or black mode", and "1-sided/2-sided".
[2]
[1] 2nd transfer roller
(a) Execution timing
• The 2nd transfer control is executed when a print job is received under any of the following conditions: "Main power switch is turned
ON" "Power key is pushed" "The machine exits the sleep mode" "The threshold value of a change in machine interior temperature is
exceeded."
(b) 2nd transfer control during image stabilization control
• In this machine, the 2nd transfer roller does not have a retraction mechanism, so that the transfer belt and 2nd transfer roller are
pressed up against each other at all times.
• During image stabilization control, a toner image for adjustment purpose is formed on the surface of the transfer belt. A negative
voltage is therefore applied to the 2nd transfer roller during image stabilization control. The amount of toner sticking to the 2nd transfer
roller is thereby reduced.
(2) Control of toner application to 2nd transfer roller
• In this machine, the 2nd transfer roller does not have a retraction mechanism, so that the transfer belt and 2nd transfer roller are pressed
up against each other at all times.
• If a new 2nd transfer roller that has replaced an old one is left to stand idle for a long period of time, a substance contained in the new
roller sticks to the surface of the transfer belt, which could result in noise in the print image.
• To prevent the substance contained in the 2nd transfer roller from sticking to the transfer belt, Y toner is applied to the surface of a new
2nd transfer roller at the time of replacement. (The Y toner image that corresponds to two complete revolutions of the transfer roller is
formed on the surface of the transfer belt and is then transfer red onto the surface of the 2nd transfer roller.)
• The Y toner that is less noticeable is used for the toner to be applied, in consideration of back marking.
(a) Execution timing
• The control is executed when the life counter of the 2nd transfer roller in the service mode is reset to zero.
(3) 2nd transfer roller cleaning
• In order to remove the remaining toner on the 2nd transfer roller, -/+ (DC) charge is applied alternately to transfer the remaining toner on
the 2nd transfer roller to the transfer belt. (The number of times that electrical charge is applied to the 2nd transfer roller is different
depending on each situation.)
• The cleaning blade then scrapes off the toner on the surface of the transfer belt.
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[3]
[1] Transfer belt
[3] Cleaning blade
(4) Paper separation control
• To neutralize any residual potential on the paper which has undergone the 2nd transfer process, there is a charge neutralizing needle
mounted on the guide plate after the 2nd transfer roller. There is a resin guide that prevents the electrode from directly contacting the
paper.
• The residual potential neutralized by the charge neutralizing needle is grounded via a conductive plate.
Service Manual
[1]
[1]
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P THEORY OF OPERATION > 1. d-Color MF4003/MF3303
[2] 2nd transfer voltage application terminal
[2]
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HV1
[2] 2nd transfer roller
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P-32
Y119930-3