Principles Of Shutter Operation; Mechanical Operatlon - Roland Series 300 Repair Manual

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I - PRINCIPLES OF SHUTTER OPERATION
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The simplest explanation of the way aU
camem
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work is: a certain amount of Ught is allowed to
fal!
on a photographic film for a certain amount
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. of time. The amount of light is controUed by the
aperture (hole) in the camera
shuuer.
The amount
of time is controlled, in the 300 Series Polaroid
land Cameras. by a photocell (electric eye) and
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associated ele<:[ronic circuitry. When a shutter
is operated. the film is expO$ed to light. and the
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Electronic Module measures the 'time of exposure'.
thereupon permitting mechanical action to close
the shutter after sufficient elapsed time.
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Since the shutteB described in this manual are
almost identical. the following mechanical and
electrical sequences
win
apply to all of them,
A. MECHANICAL OPERA nON
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I. Four basic assemblies (Fig. 1~1)
fonn the auto­
matic camera shutter: the aperture selector.
the opening blade, the closing blade, and the
electronic module.
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CLOSING
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SELECTOR
{WliEfU
SLAOE
Af"fifnURE
/
ELECTRONIC
1C::::::::::l~
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MOOULE
FIG.1-1 BASIC SHUTTER
MPONfNTS
2, The aperture seiector controls tbe light enter­
ing the camera at any moment: the opening
blade beg;ns the exposure. the dosing bbde
ends the exposure~ and the electronic module
circuits regulate the length of exposure time.
3. To operate. the shutter must first be co<:ked
'by depressing the cocking arm (Fig.
I~J).
As
the
arm moves, it pulls the cocking slide, which
in turn, pulls the opening blade to its opernting
position. While the opening blade moves. it
carries the closing blade along with it. When
the opening blade has been moved far enough,
a latch pin integral with it, forces the blade
latch down, until the pin passes a shoulder, on
the latch.
As
the pin slides beyond the latch
shoulder, the latch snaps up, securing the pin
and holding both shutter blades in the cocked
position.