Polaroid ProCam Repair Manual page 33

Energizing Solenoid 1 causes the Drive Link and Walking Beam to pivot
clockwise. This action releases the Kick Spring which strikes an arm on the
Quintic lens (Figure 1-28). The Quintic lens thus starts to pivot counterclockwise.
DRIVE LINK
Figure 1-28. Kick Spring Starts Quintic Lens Movement
As the Quintic pivots counterclockwise, light from the Encoder LED is alternately
blocked and allowed to pass through to the Encoder photodiode. These pulses of
light are created by "windows" along the outer edge of the moving lens
(Figure 1-29). The pulses are counted by the Encoder circuit and are compared to
the distance information already generated by the Transducer circuit. When the
pulse count corresponds to the distance information, Solenoid 2 is energized.
RANGING
CIRCUIT
ENCODER
CIRCUIT
Figure 1-29. Encoder Circuit Reads Light Pulses
KICK SPRING
WALKING BEAM
SOLENOID 2
WINDOWS IN
MOVING QUINTIC
1 - 27
MOVING QUINTIC
ENCODER LED