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AL-2020/2035/2040/2050/2060  COPY PROCESS  6 - 4

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 neutralized with negative charges
on the OPC layer.

The Scorotron charger functions to maintain uniform surface
potential on the drum at all times, It control the surface potential
regardless of the charge characteristics of the photoconductor.

A screen grid is placed between the saw tooth and the photocon-
ductor. A stable voltage is added to the screen grid to maintain the
corona current 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
semiconductor laser using negative to positive (reversible) devel-
oping method. Therefore, if the developing bias is added before
the drum is charged, toner is attracted onto the drum. If the devel-
oping 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 transi-
tion 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 car-
rier is pulled towards the drum by the electrostatic force of -
400V.

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

potential is switched from LOW to HIGH.

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

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

The reverse sequence takes place.

Retaining developing bias at an abnormal occurrence

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 developing 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.

Semiconductor laser

0

START

STOP

Print potential

Toner attract
potential

2)

3)

1)

Low

4)

High

Drum potential

Developing bias

Time

AL-2020/2035/2040/2050/2060  OPERATIONAL DESCRIPTIONS  7 - 1

The outline of operation is described referring to the basic configuration.

1) Set copy conditions such as the copy quantity and the copy

density with the operation section, and press the Start key. The
information on copy conditions is sent to the MCU.

2) When the Start key is pressed, the scanner section starts scan-

ning of images. 
The light from the copy lamp is reflected by the document and
passed through the lens to the CCD.

3) The image is converted into electrical signals by the CCD circuit

and passed to the MCU.

4) The document image signal sent from the CCD circuit is pro-

cessed under the revised conditions and sent to the LSU (laser
unit) as print data.

5) The LSU emits laser beams according to the print data.

(Electrical signals are converted into photo signals.)

6) The laser beams are radiated through the polygon mirror and

various lenses to the OPC drum.

7) Electrostatic latent images are formed on the OPC drum

according to the laser beams, and the latent images are devel-
oped to be visible images (toner images).

8) Meanwhile the paper is fed to the image transfer section in syn-

chronization with the image lead edge.

9) After the transfer of toner images onto the paper, the toner

images are fused to the paper by the fusing section. The copied
paper is discharged onto the exit tray.

The print data sent from the PC are passed through the NIC PWB
(in case of network connection) and the MCU to the LSU. The pro-
cedures after that are the same as above 5) and later.

The scan data are passed through the MCU to the PC according
to the conditions requested by the operations with the operation
panel.

Operation

section

Scanner section

CCD 

MCU (Main control/image process section)

USB

PC

Laser beam

Paper exit

Fusing section

Paper transport section

Manual paper

feed section

Cassette paper

feed section

Printer section

LSU (Laser unit)
Laser diode, Polygon mirror lens

Process section

NIC PWB

(AL-2040/

2050/2060)

Network

(print only)

PC

FAX modem

(AL-2060 only)

FAX

AL-2020/2035/2040/2050/2060  OPERATIONAL DESCRIPTIONS  7 - 2

The scanner unit in the digital copier scans images.

It is composed of the optical unit and the drive unit. The optical unit
performs scanning in the main scan direction with the light receiving
elements (color CCD). The drive unit performs scanning in the sub
scanning direction by moving the optical unit.

Two white lamps are used as the light source.

Light radiated from the light source is applied to the document on
the document table. The reflected light from the document is
reflected 4 times by No. 1 - No. 3 mirrors and passed through the
reduction lens to form images on the light-receiving surface of 3-line
CCD.

The light-receiving surface of the color CCD is provided with 3 line
scanning sections for RGB. Separate images scanned in each color
section are overlapped to complete color scanning. (When PC
scanning)

The resolution is 600dpi.

When copying, only the green component is used to print with the
printer.

The color component for printing can be switched to red or blue by
the service simulation.

(Spectrum characteristics of the lamp)

(Spectrum characteristics of the color CCD)

(Optical unit)

The drive system is composed of the scanner motor, the pulley
gear, the idle pulley, the idle gear, the belt 473, the belt 190, and the
shaft.

The motor rotation is converted into reciprocated movements of the
belt 473 through the idle gear, the pulley gear, the belt 190, and the
idle pulley to drive the optical unit.

100

75

50

45.4

100.0

50.2

25

380

480

580

680

780

Wavelength [nm]

Sensitivity

1

Table glass

2

Optical unit

3

Lens

4

Mirror 1

5

Mirror 2

6

Mirror 3

7

CCD PWB

8

Lamp

9

Reflector

10

Original

R

e

lative sensitivit

y

Wavelength [nm]

8

9

9

8

10

1

7

5

3

4

2

6

7

9

3

4

6

2

8

5

1

3

1

Scanner motor

2

Pulley gear

3

Idle pulley

4

Belt 473

5

Belt 190

6

Optical unit

7

Shaft

8

Idle gear

9

Table glass

AL-2020/2035/2040/2050/2060  OPERATIONAL DESCRIPTIONS  7 - 3

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 f

θ lens, etc.

The laser beams are passed through the collimator lens, the cylin-
drical lens, the polygon mirror, the f

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

Makes the laser scanning speeds at both ends of the drum same as
each other.

Effective scanning width: 216mm (max.)

Resolution: 600dpi

Beam diameter: 75um in the main scanning direction, 80um in the
sub scanning direction

Image surface power: 0.18 ± 0.01mW (Laser wavelength 770 -
795nm)

Polygon motor section: Brushless motor 20.787rpm
No. of mirror surfaces: 5 surfaces

No

 Component

Function

1

Semiconductor laser

Generates laser beams.

2

Collimator lens

Converges laser beams in parallel.

3

Cylinder lens

Takes the focus.

4

Polygon mirror, 
polygon motor

Reflects laser beams at a constant 
rpm.

5

BD (Lens, PWB)

Detects start timing of laser 
scanning.

6

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.)

2

3

3

6

4

1

5

6

a 

≠ b ≠ c

a

b

c

d = e = f

d

e

f

 

θ 

LENS