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1) The OPC drum surface is negatively charged by the main charger.

The main charger unit is provided with the screen grid. The OCP
drum is charged with the voltage virtually same as the voltage ap-
plied to the screen grid.

2) Laser beam image lights are radiated to the OPC drum surface by

the scanner (writing) unit to form latent electrostatic images.

When the OPC drum CGL is radiated by laser beams, positive
and negative charges are generated.
The positive charges generated in CGL are attracted to the nega-
tive charges on the OPC drum surface. While the negative
charges are attracted to the positive charges in the aluminum
layer of the OPC drum.
Therefore, the positive and the negative charges are offset each
other to reduce positive and negative charges, resulting in a re-
duced potential in the OPC drum surface.
The areas which are not radiated by laser beams remain charged.
As a result, latent electrostatic images are formed on the OPC
drum surface.

3) After transfer operation, residual toner on the OPC drum is re-

moved by the cleaning blade.

The toner removed from the OPC drum is transported to the waste
toner bottle by the waste toner transport screw.

4) The whole surface of the OPC drum is discharged.

Aluminum

layer

OPC drum

CTL

CGL

High voltage unit

Main corona unit

Screen grid

Aluminum

layer

CGL

CTL

OPC drum

Laser

Aluminum

layer

OPC drum

CGL

CTL

OPC drum

layer
Aluminum

CGL

CTL

OPC drum

layer
Aluminum

CGL

CTL

Discharge
lamp

AR-C150

2 – 23

Lights are radiated to the whole surface of the OPC drum by the
discharge lamp.

When the CGL of the OPC drum is exposed to the lights from the
discharge lamp, positive and negative charges are generated. The
positive charged generated in the CGL are attracted to the nega-
tive charges on the OPC drum surface. While the negative
charges are attracted to the positive charges in the aluminum
layer of the OPC drum.

Therefore the positive and the negative charges on the OPC drum
surface and in the aluminum layer are offset each other to reduce
positive and negative charges, resulting in a reduced surface po-
tential of the OPC drum.

This section converts latent electrostatic images formed on the OPC
drum surface by the scanner (writing) unit (laser beam image lights)
into visible images.

DEVELPING(C)

3

4

TONER

CONCENTRATION

SENSOR

TONER

DEVELOPPER

DEVELOPING

UNIT(C)

TONER HOPPER

UNIT(C)

TONER MOTOR

3

4

TONER

DEVELOPPER

TONER

CONCENTRATION

SENSOR

DEVELPING(K)

DEVELOPING

UNIT(K)

TONER HOPPER

UNIT(K)

TONER MOTOR

4

TONER

DEVELOPPER

DV MOTOR(BLACK)

TONER

CONCENTRATION

SENSOR

DEVELPING(Y)

DEVELOPING

UNIT(Y)

TONER HOPPER

UNIT(Y)

TONER MOTOR

DV MOTOR (COLOR)

3

3

4

TONER

DEVELOPPER

TONER

CONCENTRATION

SENSOR

TONER HOPPER

UNIT(M)

DEVELOPING

UNIT(M)

TONER MOTOR

DEVELPING(M)

PCU

PWB

PCU

SUB

PWB

PROCESS SECTION

CN111

(34pin)

CN104

(28pin)

CN401

(6pin)

CN111

(34pin)

CN104

(28pin)

CNB

(8pin)

CN702

(40pin)

DCPS

HV PWB

(TC)

BELT UNIT

HV PWB

(MC)

TC K

MC HOLDER UNIT

MC

PWB

MC K

TC C
TC M

TC Y

OZFM

LSUFM

VFM

TFD

WASTE TONER UNIT

VENTILATION

FAN DUCT UNIT

GB K

DV Bias K

MC C
GB C

DV Bias C

MC M
GB M

DV Bias M

MC Y
GB Y

DV Bias Y

PROCESS

CONTROL

PWB

DCPS

CN8

(3pin)

CN6

(3pin)

CN9

(10pin)

CN7

(10pin)

CN4

(3pin)

CN5

(10pin)

CN2

(3pin)

CN3

(10pin)

CN10

(12pin)

CN702

(40pin)

PCU

PWB

CN113

(34pin)

CN112

(32pin)

CN1

(15pin)

DV/TONER HOPPER SECTION

DLK

DMSK

TCSK

DLC

DMSC

TCSC

DLM

DMSM

TCSM

DLY

DMSY

TCSY

DV UNIT

TONER HOPPER UNIT

TMK

TMY

TMM

TMC

AR-C150

2 – 24

No.

Parts

Note

Code

Signal

name

Name

Type

Function/Operation

Active

condition

1

Developing unit (Y)

Changes yellow latent electrostatic
images to visible toner images.

2

Developing unit (M)

Changes magenta latent electrostatic
images to visible toner images.

3

Developing unit (C)

Changes cyan latent electrostatic
images to visible toner images.

4

Developing unit (K)

Changes black latent electrostatic
images to visible toner images.

5

DV seal

Shields and prevents toner from
leaking.

6

DV side seal F

Shields and prevents toner from
leaking.

7

DV side seal R

Shields and prevents toner from
leaking.

8

DMS 
(Y, M, C, K)

DMS 
(Y, M, C, K)

Drum mark sensor

Photo sensor
(Photo reflection)

Detects the mark on the OPC drum.

Analog
input

Controls the OC
drum phase and
identifies it.

9

Doctor

Controls toner quantity on the
developing roller to be even.

10

6

7

8

1

5

9

2

3

4

11

12

13

14

13

13

AR-C150

2 – 25

No.

Parts

Note

Code

Signal

name

Name

Type

Function/Operation

Active

condition

10

Developing roller
main pole position
adjustment plate

Adjusts the developing roller main
pole position.

11

TCS 
(Y, M, C, K)

TCS 
(Y, M, C, K)

Toner concentration
sensor

Magnetic

Detects the ratio of carrier and toner
in the developing unit.

Analog
input

Installed to each
developing unit.

12

Developing roller

Adheres toner onto the OPC drum.

13

Toner mixing roller

Stirs toner and carrier to make the
toner concentration even and
charges the both.

14

Absorbing duct

Removes toner dispersed around the
developing roller.

Prevents against
dirty copy by
dispersed toner.

In the developing unit, carrier and toner are mixed and stirred by the
toner mixing screw.

By stirring, the toner concentration in the development unit is uni-
formed, and toner is charged negatively and carrier positively by me-
chanical friction.

The developing bias voltage (negative) is applied to the developing
roller. Negatively charged toner is attached by the developing bias
voltage to the area on the OPC drum surface where the negative po-
tential was reduced by exposure of laser beams.

While the area on the OPC drum surface where exposure was not
made by the laser beams has higher negative potential, and repels
toner.

The developing unit is provided with the toner concentration sensor to
detect the toner concentration.

When the toner concentration in the developing unit decreases, toner
is supplied from the toner hopper.

The developing unit is provided with the absorption duct, which re-
moves toner attached around the seal.

∗

The developing unit is provided with the OPC drum marking sensor
to detect the drum marking to perform the following:

1) Identification of OPC drum

2) Image position control on the OPC drum in forming latent electro-

static images

∗

To provide the constant developing conditions, the distance
between the developing roller and the OPC drum must be
maintained constant.
To realize this, the DSD holder is installed to the front and the rear
frame sections of the developing unit of each color and the OPC
drum unit.

∗

The developing section is controlled by the process control PWB.

∗

The process control PWB is provided with the temperature sensor,
and the result of sensing by the sensor is reflected to the
correction of the image forming section.

Aluminum

layer

CGL

CTL

OPC drum

Developing roller

Toner
concentration
sensor

DSD holder

AR-C150

2 – 26