Ricoh FT5034, Service Manual

Page: 46 / 139

3. Erase Lamp
The erase lamp illuminates the area of the charged drum surface that will not be
used for the copy image.
The erase lamp reduces toner consumption and the drum cleaning load.
The erase lamp consists of a line of 64 LEDs extending across the full width of the
drum.
The erase lamp performs lead edge erase and side erase.
The erase lamp unit also has two thermistors: TH-1 and TH-2.
Both of these thermistors detect the temperature around the drum.
TH-1 determines the proper rest time compensation, and TH-2 controls the
development bias voltage.
A: Lead Edge Erase Margin --- 3.5
±
0.5 mm
B: Side Margins --- 2
±
2 mm each
(For full size copies the total of both side
margins is less than 4 mm.)
L
O
: Original Image width
L
C
: Charged width on the Drum
E
L
: Lead Edge Erase
E
S
: Side Erase
R: Lead Edge Registration --- 0
±
2 mm
A+R: Lead Edge Blank Margin --- 3.5
±
2.5 mm
Erase Unit
Charged Area
Charge
Corona Unit
Original Lead Edge
Front Endblock
Cover
[Density Detection Cycle]
Sensor Pattern
Charged Area
Left Scale
Original Lead
Edge
Original
Sensor Pattern
Exposure Glass
Original Lead
Edge
Toner Image
Paper
Sensor
Pattern
- 45 -