Ricoh FT4460, Service Manual, Page: 65 / 413

28 February 1989
3.5 LENS POSITIONING
: Reduction
: Enlargement
The lens home position sensor [A] informs the I/O control PCB when the lens
is at full size position (home position). The I/O control PCB determines the
lens stop position in reduction and enlargement modes by counting the num-
ber of steps the motor makes with reference to the lens home position. When
a new reproduction ratio is selected, the lens [B] moves directly to the
selected magnification position.
The lens home position is registered each time the lens starts from or passes
through the lens home position sensor. As the lens moves from right to left
(as viewed from the front), the sensor registers the home position. This oc-
curs when the actuator plate [C] enters the lens home position sensor.
A small vibration can be observed when the lens moves through home posi-
tion from enlargement to reduction because the lens is going in the wrong
direction to register. The lens overshoots the home position by only one pulse
before going back to reference the home position.
The lens always stops while moving from left to right to minimize the error
caused by mechanical play in the drive gears [D].
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