Mita-Kyocera FS5900C Mechanical Functions

FS-5900C Service Manual

4. Mechanical Functions

4.1 Drive Mechanism/Image Process General Description

Drive Mechanism

Eight DC servomotors are used to transmit drive to each mechanical block within the engine. The main motor transmits drive to the imaging unit. The paper feed motor transmits drive to the paper feed unit, fuser unit and toner developer selector/paper eject unit. The toner developer motor transmits drive to the toner developers. Four cam motors in the toner developer selector/paper eject unit mov e the toner develop er to their development position. The MP tray paper feed motor in the paper feed unit is the stepping motor and feeds the paper in the multi-purpose tray.

The paper feed unit, laser scanning unit, toner developers, fuser unit and toner developer selector/paper eject unit are designed for easy removal from the printer for easy maintenance.

Print Process

The laser printer creates an image on paper using a technique called laser electrophotography. The printer uses the electrog raphic process known as t he disc harged are a deve lopment, or write bla ck. In this process, a digitally modulated laser scans laterally across a rotating OPC belt that has been negatively charged. Wherever the belt is exposed by the laser beam, the image is written and toner is transferred.

To generate a color image, the OPC belt must complete four rotations, one for each primary color and black. During each successive pass, the laser exposes the portions of belt that correspond to the primary color’s component of the image. Toner is attracted to the laser-exposed portions of the belt.

As each color layer is developed on the OPC belt, they are transferred to the accumulator belt until all four color layers eventually reside one on top of the o ther on the accumulator belt . At this point, a sheet of pap er is advanced under the accumulator belt and the toner is transferred to the sheet of paper. The pape r advances to the fuser, where heat and pressure permanently bond the toner to the paper. From the fuser, the paper is driven to the output tray.

A cleaning blade scrapes residual toner from the OPC belt before the next primary color toner is applied to the belt. This prevents contamination of the next color layer. The cleaning blade is in constant contact with the belt. An accumulator belt cleaner scapes residual toner from the accumulator belt. This preve nts “ghosting” of the next print. The blade only comes in contact with the belt after the accumulated toner layers are transferred to the sheet of paper.

Drive Unit Layo u t

Toner Developer Selector/ Paper-eject Unit

Cam Motor

Laser Scanning Unit (LSU)

Imaging Unit

Main Motor

Paper Feed Unit

MP Tray Paper Feed Motor Paper Feed Motor

Toner Developer Toner Developer

Drive Motor

Fuser Unit

Print Process

4. Mechanical Functions

Laser Scanning Unit (LSU)

Multipurpose Tray Pickup Roller

Intermediate Rollers

Pickup Roller

Transfer Roller (+300 V)

Erase Lamp

OPC Belt Cleanning Blade

OPC Belt Cleaner

First Bias Transfer

Roller Accumulator Belt

Registration Rollers

Scorotron Charger

+500 ~ 700 v

Waste Toner

Bin Cleaning Roller

(+500 to 2600, depending on media and humidity)

Second Bias Transfer Roller

OPC Belt

Accumulator Belt Cleanning Blade

On-Off

Supply Roller

Toner Cartridges

Black

Cyan

Magenta

Yellow

Pre-Transfer Lamp

Fuser

Toner Cartridge Selector Cam

Take-up Roller

Heated Roller

Pressure Roller

Each block is explained in the following sections:

1. 4.2.1 Discharge and Charging

2. 4.2.2 Laser Exposure and Scanning

3. 4.2.3 Developing

4. 4.2.4 Toner Transfer to the Accumulator Belt

5. 4.2.5 Paper Pickup

6. 4.2.6 Toner Transfer to Paper

7. 4.2.7 Fusing and Exiting

FS-5900C Service Manual

OPC Belt

Laser Beam from LSU

4.2 Print Process

4.2.1 Discharging and Charging

Discharge

The print process begins when the OPC belt passes by the erase lamp. The belt is rotating at 100 mm-per-second for 600 dpi printing or 53 mm-per-second for 1200 dpi printing. The light of the erase lamp, which is a horizontal row of red LEDs, removes random negative charges from the OPC belt. Before pre-exposure, the surface of the belt varies from -500 volts to +50 volts. After pre-exposure, the surface of the belts is 0 to -20 volts. The pre-erase lamp is called the erase lamp since it erases negative charges from the belt.

Charge

The electrostatic potential of the belt is not uniform following discharging. As the belt rotates, it passes a scorotron charger, which bombards the belt with negative charges. The scorotron charger behaves somewhat like a vacuum tube. The grid of the charger, held at a potential of between -450 volts to -600 volts and coupled with the varying voltage potential on any discrete point on the belt’s surface, determines how many electrons can flow from the corona wire onto that point of the belt’ s surface. The corona wire is charged to -5 kilovolts with a constant current of -400µA. The varying electron output from the scorotron, directly based on the varying charge of the belt surface, ensures a uniform negative potential of -440 volts or -590 volts on the belt surface, depending on the selected dot-per-inch printing and ambient temperature.

Erase Lamp

Scorotron Charger

Tungsten Wire

OPC Belt

Grid -450 ~ -600v

-5kv

4.2.2 Laser Exposure and Scanning

Laser Exposure

As the OPC belt rotates, the uniformly charged belt is exposed by the modulated laser beam. The verticallymoving belt passes in front of the horizontall y scanning laser beam, and negative charges on the belt surface are neutralized by the beam. This forms a latent image.

Laser output power is either 0.26 mW or 0.33 mW, depending on whether the printer is printing in 1200 dots per inch (dpi) mode or 600 dpi mode. The laser exposure, the negative potential on the belt varies from -440 volts or -590 volts (unexposed) to -10 or -20 volts (fully exposed).

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