Service manual

II. LENS DRIVE SYSTEM

A. Movement of the Lens

1. Outline

The lens assembly is driven by the lens motor (M3).

The machine uses center reference, in which copy paper is centered along the

feeding path for pick-up and feeding. Figure 3-201 shows the spatial relationship

between copy paper and original.

When the power switch is turned on, the lens motor (M3) starts to rotate, moving the

lens in the direction of the lens home position sensor (PS19). The lens motor starts to

rotate in reverse when the signal plate blocks the lens home position sensor, and stops

when the lens is at Direct position.

The microprocessor on the DC controller remembers the Direct position of the lens.

When the ratio is changed, drive pulses corresponding in number to the selected ratio

will be applied to the lens motor to promptly change the position of the lens.

When moving in Enlarge direction (as from Reduce to Direct), the lens is first moved

past the position for the selected ratio; it is then moved back to the appropriate position

by rotating the lens motor in reverse, thereby ensuring correct positioning of the lens.

Figure 3-201

3-2

CHAPTER 3 EXPOSURE SYSTEM

Copyboard glass

Original

Copier

Reference

Copy paper