Sharp AR-810 (serv.man15) Service Manual ▷ View online
AR-651/810 DRUM/CLEANER UNIT 11 - 1
11. DRUM/CLEANER UNIT
11. 1. Construction
This chapter describes about the drum and cleaner unit related units, parts, control circuit, etc.
The cleaner unit consists of the drive section, cleaning section, recovered toner transport section,
image quality sensor, drum separation finger, etc.
[Sectional view]
G16
G15
G25
G17/30
[Drive system]
Drum separation finger
Drum cleaning blade
Drum cleaning brush
Recovered toner
transport auger
Image quality sensor
Drum recovery blade
Drum thermistor
Drum
AR-651/810 DRUM/CLEANER UNIT 11 - 2
11. 2. Functions
(1) Drum cleaning blade
It is pushed to the drum with a certain pressure by a weight and scrapes off the residual toner on the
drum surface. The pressure is released and the blade is separated from the drum by turning the cam
manually.
(2) Drum recovery blade
It catches the toner scraped by the drum cleaning blade.
(3) Recovered toner transport auger
It transports the scraped toner to the recycle unit.
(4) Drum separation finger
It is pushed to the drum by a solenoid only when the leading edge of the paper passes in order to
separate the paper which has not been separated by the transfer belt.
(5) Image quality sensor
It assesses the relative reflective rate for the test pattern (toner image) formed on the drum in order to
keep the image density and line width properly.
(6) Drum thermistor
Since the charging amount changes depending on the temperature of the drum surface, the drum
thermistor detects the temperature of the drum surface and controls to unify the charging amount.
(7) Drum cleaning brush
It eliminates the paper dusts and extraneous substance adhered to the drum surface after separating
the paper and also decrease the friction of the drum cleaning blade to lengthen its life span, which
improves the image reliability.
11. 3. Drum Temperature Detection Circuit
Drum temperature detection circuit
At this detection circuit, the voltage gained by the R33 and thermistor is input into the A/D converter of
IC 58 to detect the drum surface temperature.
R33
+5V
C186
R32
IC58
Main
CPU
Thermistor
AR-651/810 DRUM/CLEANER UNIT 11 - 3
11. 4. Image Quality Control
11. 4. 1. General description
This copier carries out the image quality control with the image quality sensor. The image quality control
is for changing the image formation condition to minimize the changing of the image density and line
width caused by the environment and life.
The image quality sensor detects the density of the test pattern developed on the drum, and the image
formation condition is changed depending on the result.
11. 4. 2. Principle of sensor
The image quality sensor applies the light to the drum and toner image (test pattern) developed on the
drum and outputs the voltage corresponding to its reflected light amount.
A relative reflectivity is assessed by the reflected light amount obtained by the image quality sensor.
Drum
Image quality sensor
Light emitting element
Light sensing element
Test pattern
(toner image)
Light source intensity signal
Reflected light intensity signal
AR-651/810 DRUM/CLEANER UNIT 11 - 4
11. 4. 3. Outline of control
Start controlling (e.g. during the pre-running after the power has been turned ON)
[1] Setting of the reference image formation condition
[2] Adjustment of the sensor light source
[3] Formation of the test pattern
[4] Reading of the value for the image quality sensor
[5] Determination
Back to [3]
(Is the toner amount of the test pattern within the permissible amount?)
[6] Changing of the image formation condition
[7] Finish controlling
(Reflecting the determined image formation condition to the following printing)
촞
촞
촞촞
촞
YES
NO
