Shutter System - Polaroid Joshua Vision Service Manual

Shutter System (Figures 1-17, 1-18 and 1-19)
Key components of the Joshua shutter system, shown in Figure 1-17, include the Front Lens, Far Focus
Lens and its Solenoid 2, Walking Beam, Inertia System, the two Blades and their Solenoid 1 and Ambient/
IR Lens. The Blade Position Encoder system (Figure 1-18) includes the band of vertical slots near the
bottom of the Blades, a photodiode and photo-transistor (Figure 1-18) on the PC board, and circuits in the
Exposure IC. Because the Joshua is a single-lens reflex (SLR) camera in which the image is viewed through
the taking lens, the shutter must normally be open for subject viewing. The Blade Opening Spring attached to
the Walking Beam holds the Blades in this normally-open position, until they are closed prior to exposure by
rotation of the Walking Beam, when Solenoid 1 is energized.
Figure 1-17. Key Components of the Joshua Shutter System
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