IMPROVEMENTS IN PHOTOGRAPHIC SHUTTERS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I FREDERICK WOODWARD BRANSON of Leeds in the County of York
Pharmaceutical Chemist do hereby declare the nature of said Invention for
"IMPROVEMENTS IN PHOTOGRAPHIC SHUTTERS" to be as follows:-
My Invention has reference to improvements in photographic shutters for
which Letters Patent were granted to Richard Reynolds and myself dated
2nd April 1883 N° 1650.
According to my present Invention on the end of the spindle which carries the
flap I mount a lever having thereon a suitable adjustable weight, by altering
the position of the weight upon the lever, the flap may be actuated at different
velocities and the time of exposure be thereby varied.
The lever may be moved and fixed at any desired angle or position on the flap
spindle so that it may be applied in some cases for opening the flap to allow
the drop to fall; or when required by throwing the lever over to the opposite side
of the centre of the flap spindle and fixing it there to retain the flap closed until
it is raised by a movement imparted to the flap spindle by the attendant.
Instead of the weight being placed on the adjustable lever in some cases it may
be found preferable to attach a cord or its equivalent to such lever at any suitable
point; such cord or its equivalent being passed over a pulley on the upper part of
shutter, the required weight being suspended to the other end. Other parts of the
photographic shutter are similar to those described in the Specification of the above
named Letters Patent..

page_text: opposite side of the centre of the flap spindle and fixing it there, to retain the flap o
closed until it is raised by a movement imparted to the flap spindle d by the
attendant by means of the milled head i.
When a very short time of exposure is required the arm or lever ƒ is fixed in
such a position on the spindle d, so that the weight g tends to raise the flap c when
the latter is released from the catch k.
When an exposure of about a quarter of a second is required, the elastic band n
is removed and the flap o is raised by means of the weighted arm f..
Very slow exposures are made by fixing the drop b by means of the pin m
attached to the body of the shutter, the movement being imparted to the flap c
by the attendant by means of the milled head i.
The slowest automatic action of the shutter is obtained without the rubber
band n when the arm f and the weight g are arranged at an angle of about
20 degrees with the vertical as shewn in Fig. 3. If a rather quicker motion is
wanted the weight g and the arm f are placed at an angle of about 40 degrees
with the vertical, and the weight g is moved to the extreme end of the arm f.
Two additional accelerations for medium exposures may be obtained by using
a long and weak rubber band in conjunction with the weight. The band has
more or less tension according as it is placed on the upper or lower pin. (p and o
respectively.
When the quickest action of the shutter is desired, the weighted arm f is released
by means of the milled headed nut h, and the requiste motion is imparted with
a sufficiently strong rubber band placed over the upper pin p, which gives a
downward pressure to the drop b and a rapid and upward rotary movement to
the flap c.
Instead of the weight g being placed on the adjustable arm or leverf in some
cases it may be found preferable to attach a chord or its equivalent to such lever f
at any suitable point and to pass the chord over a pulley on the upper end of the
shutter a.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is:
1°.The arrangement and application of the lever f having thereon the adjustable
weight g and attached to the spindle & substantially as and for purposes
.herein set forth,
2°. The general arrangement and combination of the various parts forming my
improved photographic shutter substantially as herein described and shewn
in the accompanying Drawings.
Dated this Thirteenth day of August 1884.
.