Toshiba e-STUDIO556 Service Manual page 127

Multifunctional digital systems

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Main charger

The main charger is configured by stretching a charger wire between two insulation blocks

provided at both ends of the U-shaped metal rod.

When a high voltage is applied to the charger wire, the air around the wire is ionized

(electrostatically charged), and this ionized air is attracted onto the drum's surface. This

phenomenon is referred to as the "corona discharge". In the dark, the surface of the drum is

negatively (-) charged by the corona discharge of the main charger.

Charger wire cleaner

It removes stains on the charger wire regularly to avoid poor charging and drum irregularities.

The charger wire cleaner pad is pushed against the charger wire and moved to and fro on the

wire to clean it. The charger wire cleaner drive motor (M12) moves the charger wire cleaner to

It cleans the wire when the power is turned ON, the cover interlock switch (SW8) is turned ON or

2000 or more continuous copies have been made since the previous cleaning.

Discharge LED (ERS)

Discharging is a process of reducing or eliminating the electrostatic charges on the drum. The

discharge LED have two effects: a cleaning effect and a pre-exposure one. The cleaning effect

neutralizes and eliminates the residual charges on the drum surface by lowering the electrical

resistance of the photosensitive surface as a result of exposing it to the light, and the pre-

exposure effect keeps a fixed drum surface potential before the charging process. There is an

array of 14 LEDs with a 660 nm wavelength.

Ozone filter

Ozone produced by corona discharge of the main charger is exhausted through this filter. The

catalyzer of the ozone filter degrades the ozone.

Drum surface potential sensor (S13)

It detects the surface potential of the photoconductive drum and performs control to keep the

difference between the surface potential and the development bias constant.

High-voltage transformer

This board creates the output control voltage of the main charger, charge grid, power supply

roller and developer bias.

Temperature/Humidity sensor (S7)

This sensor (S7) and drum thermistor (THM5) detect the temperature and humidity inside of the

equipment since the drum, developer material and paper are affected by environmental elements

such as temperature or humidity. Thus the main charger grid, transfer belt, developer bias, laser

output and auto-toner output are controlled to be at their optimum states.

The temperature/humidity sensor (S7) is installed in the control panel.

e-STUDIO556/656/756/856/557/657/757/857

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