Scanner Drive - Ricoh FT4220 Service Training Manual

3.2 SCANNER DRIVE

[A]
3.2.1 1st and 2nd Scanner Drive Mechanism
This model uses a stepping motor [A] to drive the scanners. Both ends of
each scanner are driven to prevent skewing. The scanners have sliders [B],
which ride on guide rails.
The scanner home position is detected by the home position sensor [C]. The
scanner return position is determined by counting the scanner motor drive
pulses.
The first scanner [D], which consists of the exposure lamp and the first mirror,
is connected to the scanner drive wire by the wire clamps [E]. The second
scanner [F], which consists of the second and third mirrors, is connected to
the scanner drive wire by movable pulleys (the second scanner pulley [G]).
The pulley moves the second scanner at half the velocity of the first scanner.
This is to maintain the focal distance between the original and the lens during
scanning. This relationship can be expressed as:
V1r
where r = Reproduction ratio
V1r
V2r
VD
FT4220/4222
[D]
[E]
[G]
= 2 (V2r) = VD/r
= First scanner velocity (when the reproduction ratio
is "r")
= Second scanner velocity (when the reproduction ratio
is "r")
= Drum peripheral velocity (120 mm/s)
2-10
[B]
[F]
[C]
STM