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AL-1611/AL-1622

OPERATIONAL DESCRIPTIONS

6 – 2

The light from the light source (Xenon lamp) is reflected by a document and passed through three mirrors and reduction lenses to the CCD element

(image sensor) where images are formed. This system is known as the reduction image sensor system. Photo energy on the CCD element is con-

verted into electrical signals (analog signals). (Photo-electric conversion). The output signals (analog signals) are converted into digital signals (A/D
conversion) and passed to the MCU (main control/image process section). The resolution at that time is 400dpi. The mirror unit in the scanner section

is driven by the mirror motor. The MHPS is provided to detect the home position of the copy lamp unit.

1

Copy lamp (Xenon lamp)

Generate photo energy to scan documents.

2

Reflector (Converging plate)

Collects light emitted from the copy lamp and radiate the document.

3

No. 1 mirror

Refracts the reflection light from the document to No. 2 mirror.

4

No. 2 mirror

Refracts the reflection light from No. 1 mirror.

5

No. 3 mirror

Refracts the reflection light from No. 2 mirror.

6

Lens

Converges reflected light from the document to form images on the CCD element.

7

No. 2/3 mirror unit

Includes No. 2/3 mirror. Driven in synchronization with the copy lamp unit.

8

Copy lamp unit

Includes the copy lamp, the reflector, and No. 1 mirror. Driven in synchronization with No. 2/3
mirror unit by the mirror motor.

9

CCD PWB

Reflected light (image) formed on the CCD is converted into electrical signals (analog signals)
then into digital signals and sent to the MCU.

10

Mirror motor

Drives the copy lamp unit and No. 2/3 mirror unit according to the scanning speed.

11

MHPS (Mirror home position sensor)

Detects the home position of No. 2/3 mirror unit.

12

Reference white plate

Reference white sheet for scanning documents. The reference line of magnification ratio
adjustment during SIM is also drawn.

13

OC glass

Glass table to put a document on it.

1

Main charger unit

Charges the OPC drum.

2

Cleaning blade

Collects waste toner on the OPC drum.

3

OPC drum

Images are formed by laser beams electri-
cally, and toner is attached to the image.

4

Transfer unit

Toner on the OPC drum is transferred to the
print paper by the potential difference.

5

Resist roller

Makes synchronization between the paper
and the print image.

6

MG roller

Magnetic brush is formed by developer to
put toner on the OPC drum.

7

(Laser beam)

Forms images on the OPC drum.

AL-1611/AL-1622

OPERATIONAL DESCRIPTIONS

6 – 3

The printer section of this machine employs the laser print system
where print images are formed by the laser beams on the OPC drum.

A high voltage (corona) is applied from the main charger to the OPC

drum to charge the OPC drum. 

Laser beams are radiated to the charged OPC drum to form electrical
images on the OPC drum. (Exposure)

(At that time, the print image on the OPC drum cannot be seen: latent

electrostatic image)

By the potential difference between the unexposed area and the latent
electrostatic images, toner ia attracted only to the images. (Developing)

(At that time, the print image formed by toner on the OPC drum can be

seen. Visible images)

The toner image on the OPC drum is transferred on the print paper by
the transfer corona (voltage). 

After that, the print paper with the toner image on it is subject to heat

and pressure in the fusing section to fuse the image on the paper.

This machine employs the following organic photoconductor (OPC)
drum.

A high voltage is applied to the main charger, and negative charges are

discharged to the OPC drum. A screen grid is provided between the
main charger and the OPC drum, and negative charges are uniformly

charged on the OPC drum surface.

Positive charges are attracted by the negative electrode on the OPC

drum surface and excited in the aluminum layer in the OPC drum.

Paper exit roller

Paper exit

Heat roller

Fusing

Cleaning blade

Waste toner box

Separation

Cleaning

Separation charger

High voltage power

High voltage power

Main charger

Charging

Transfer

Transfer

Transfer charger

High voltage power

Laser scanning unit

Laser beam

Exposure

Developing

Synchronization 
with drum

Resist roller

High voltage
power

Developing unit

Toner hopper

Developer

Toner

Cassette paper 
feed

Manual paper 
feed

(20microns thick)

Aluminium drum

Pigment layer (0.2
to 0.3 microns thick)

An OPC drum is used for the photoconductor.
(Structure of the OPC drum layers)

OPC layer

DC5.5KV

(-525V/-400V)

AL-1611/AL-1622

OPERATIONAL DESCRIPTIONS

6 – 4

A Laser beam is generated from the semiconductor laser and controlled
by the print pattern signal. The laser writes onto the OPC drum surface

through the polygon mirrors and lens. The resistance of the OPC layer

decreases for an area exposed by the laser beam (corresponding to the
print pattern signal). The beam neutralizes the negative charge. An

electrostatic latent image is formed on the drum surface.

A bias potential is applied to the MG roller in the two component mag-
netic brush developing method, and the toner is charged negative

through friction with the carrier. Non-image area of the drum surface

charged with negative potential repel the toner, whereas the laser
exposed portions where no negative charges exist, attract the toner. As

a result, a visible image appears on the drum surface.

Toner is attracted over the shadowed area because of the developing
bias.

The visible image on the drum surface is transferred onto the print
paper by applying a positive charge from the transfer corona to the

backside of the print paper.

Since the print paper is charged positively by the transfer corona, it is

discharged by the separation corona. The separation corona is con-
nected to ground.

Toner remaining on the drum is removed and collected by the cleaning
blade. It is transported to the waste toner collecting section in the clean-

ing unit by the waste toner transport roller.

OPC layer

Pigment
layer

Aluminum

OPC layer

Pigment
layer

Aluminum
layer

Drum surface charge
sfter the exposure

Non-image area

Image area

Semiconductor laser

Exposure
(semiconductor laser)

layer

S

N

N

MG roller

 

DC
-400v

-8V

: Carrier (Magnetized particle)

: Toner (Charge negative by friction)

(N) (S) : Pemanent magnet
            (provided in three locations)

-600

0

Toner attract
potential

D

ru

m

 s

u

rfac
e p

o

te

nt

ia

l

Non-image area

Developing bias

Image area

Residual potential (-50 to -100V)

Charge

Exposure

Developing

Transfer

Discharge

Charge

Time

-400

AL-1611/AL-1622

OPERATIONAL DESCRIPTIONS

6 – 5

Before the drum rotation is stopped, the semiconductor laser is radiated

onto the drum to reduce the electrical resistance in the OPC layer and
eliminate residual charge, providing a uniform state to the drum surface

for the next page to be printed.When the electrical resistance is

reduced, positive charges on the aluminum layer are moved and neu-
tralized with negative charges on the OPC layer.

The Scorotron charger functions to maintain the surface potential of the

drum even at all times which. It is used to control the surface potential

regardless of the charge characteristics of the photoconductor.

A screen grid is placed between the saw tooth and the photoconductor.
A stable voltage is added to the screen grid to maintain the corona cur-

rent on the photoconductor. As the photoconductor is charged by the

saw tooth from the main corona unit, the surface potential increases.
This increases the current flowing through the screen grid. When the

photoconductor potential nears the grid potential, the current turns to

flow to the grid so that the photoconductor potential can be maintained
at a stable level.

The print pattern signal is converted into an invisible image by the semi-
conductor laser using negative to positive (reversible) developing

method. Therefore, if the developing bias is added before the drum is

charged, toner is attracted onto the drum. If the developing bias is not
added when the drum is charged, the carrier is attracted to the drum

because of the strong electrostatic force of the drum.

To avoid this, the process is controlled by adjusting the drum potential
and the grid potential of the Scorotron charger.

Voltage added to the screen grid can be selected, high and low.To

make it easily understood, the figure below shows voltage transition at

the developer unit.

1) Because the grid potential is at a low level, the drum potential is at

about -400V. (Carrier may not be attracted though the carrier is

pulled towards the drum by the electrostatic force of -400V.)

2) Developing bias (-400V) is applied when the photoconductor poten-

tial is switched from LOW to HIGH.

3) Once developing bias (-400V) is applied and the photo conductor

potential rises to HIGH, toner will not be attracted to the drum.

The reverse sequence takes place.

The developing bias will be lost if the power supply was removed during

print process. In this event, the drum potential slightly abates and the

carrier makes deposits on the drum because of strong static power. To
prevent this, the machine incorporates a function to retain the develop-

ing bias for a certain period and decrease the voltage gradually against

possible power loss.

Normally, the developing bias voltage is retained for a certain time
before the drum comes to a complete stop if the machine should stop

before completing the normal print cycle. The developing bias can be

added before resuming the operation after an abnormal interruption.
Therefore, carrier will not make a deposit on the drum surface.

The image data sent from the MCU (image process circuit) is sent to the

LSU (laser unit), where it is converted into laser beams.

The LSU unit is the writing section of the digital optical system.The

semiconductor laser is used as the light source, and images are formed

on the OPC drum by the polygon mirror and fq lens, etc.

The laser beams are passed through the collimator lens, the cylindrical

lens, the polygon mirror, the fq lens, and the mirror to form images on
the OPC drum in the main scanning direction. The laser emitting PWB

is provided with the APC (auto power control) in order to eliminate fluc-

tuations in the laser power. The BD PWB works for measurement of the
laser writing start point.

Semiconductor laser

0

START

STOP

Print potentioal

Toner attract
potential

2)

3)

1)

Low

4)

High

Drum potential

Developing bias

Time

1

Semiconductor laser

Generates laser beams

2

Collimator lens

Converges laser beams in parallel

3

Polygon mirror, 
polygon motor

Reflects laser beams at a constant rpm

4

BD (Mirror, lens, PWB) Detects start timing of laser scanning

5

f

θ

 lens

Converges laser beams at a spot on
the drum.
Makes the laser scanning speeds at
both ends of the drum same as each
other. (Refer to the figure below.)

6

Laser emitting PWB

Emits laser beams according to the
image data.

6

5

2

1

3

4