Control; Control Of Paper Size; Selective Control On Paper Pick-Up Unit; Scanner Light Quantity Control - Brother HL-4000CN Service Manual

7.

CONTROL

7.1

Control of Paper Size

"ON/OFF of paper size switch of switch ASSY size " and "Diag tool indication data" are
shown in the table below.
Note:
Paper size switches are indicated as SW1, SW2, and SW3 from the above one.
Paper size
LEGAL14"
LEGAL13"
EXECUTIVE
B5
A4
LETTER
A5
No cassette
7.2

Selective Control on Paper Pick-up Unit

When not controlled by the printer controller, paper pick-up unit selected at the time of
turning ON are as follows.
Note:
The paper feeder by the paper tray under the printer is called "Tray 1", and the first tray
and the second tray in optional tray unit are called "Tray 2" and "Tray 3" respectively.
7.3

Scanner Light Quantity Control

The image data are entered to the laser diodes in the scanner ASSY as electric signals
(data are expressed with high and low voltage values), and the laser diodes convert the
image data from electric signals to optical signals (data are expressed with blinking laser
beams).
Variations in light quantity of laser beams or variations in optical system (such as lenses)
or drum sensitivity cannot attain proper electrostatic image, and accordingly the laser
diodes monitor the light quantity of laser beams to control the light quantity so as to attain
stable and proper electrostatic image.
The scanner in this printer has four laser diodes for yellow, magenta, cyan, and black
respectively, and the light quantity is automatically adjusted for each color.
7.4

Process Control

For a stable printing, the parameters related to the image forming must be corrected as
necessary. The control of entire printing process including parameter correction control
is called "process control".
Mainly, the following two controls are made:
To supplement these two controls, the following controls are provided:
SW1
ON
ON
ON
ON
OFF
OFF
OFF
OFF
Potential control
Toner density control
High area coverage mode
Admix mode
Holder ASSY CTD LED light quantity setting
III-43
Paper size switch
SW2 SW3
ON ON
ON OFF
OFF ON
OFF OFF
ON ON
OFF ON
ON ON
OFF OFF
Diag
indication data
00
01
02
03
04
06
07