Ricoh FT5233 Service Manual page 55

OPTICS
4.2 SCANNER DRIVE
[D]
This model uses a stepper motor [A] to drive the scanners via a timing belt
[B], scanner drive pulley [C], and 2 long & short scanner drive belts [D, E].
Both ends of each scanner are driven to prevent skewing. The scanners
have sliders [F], which ride on guide rails.
The scanner home position is detected by the home position sensor [G]. The
main CPU sends the appropriate pulses to the scanner drive motor to
determine the scanner return position.
The first scanner [H], which consists of the exposure lamp and the first mirror,
is connected to 2 long scanner drive belts by the belt clamps. The second
scanner [I], which consists of the second and third mirrors, is connected to 2
short scanner drive belts by belt clamps.
The relay pulley moves the second scanner at half the velocity of the first
scanner. The diameter of the pulley for the short belts is half that for the long
belts. This is to maintain the focal distance between the original and the lens
during scanning. This relationship can be expressed as:
V = 2 (V
1r
where r = Reproduction ratio
V = First scanner velocity (when the reproduction ratio is "r")
1r
V = Second scanner velocity (when the reproduction ratio is "r")
2r
V = Drum peripheral velocity (180 mm/s)
D
[E]
[H]
[E]
[G]
[A]
) = V /r
2r D
2-26
[C]
[B]
12 February 1992
[F]
[I]