AN ADJUSTABLE INSTANTANEOUS SHUTTER, FOR PHOTOGRAPHIC PURPOSES
Year: 1884

page_text: I, THOMAS FURNELL of N° 1 Matlock Villas Lordship Lane East Dulwich,
London in the County of Surrey, Civil Engineer, do hereby declare the nature
of my Invention for AN ADJUSTABLE INSTANTANEOUS SHUTTER, FOR PHOTOGRAPHIC
PURPOSES, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The frame, of the shutter, is composed of a rectangular piece of wood, or other
suitable material; and marked V, on plan, to be of rather larger dimensions, than
required to fit either; the lens mount, or hood, the back part turned out to fit
either of the above. The front, part; has a rectangular opening, large enough to
allow, an amount of light, to enter the lens, sufficient, for all practical, purposes, of
exposure. The rectangular opening, allowing the use of smaller, shutters, for the
same, effect, than those usually employed, and so reduce bulk. Attached, to this
frame by wood screws, or otherwise; are two side plates, of sheet brass; or other
metal, and marked T, and U, on plan. so formed as to admit of the ends of the
two shafts, Q, and P. to pass through; or rest on bearings; which is so, at one end
of the shaft Q. On the shafts Q and P, aré shutters, S. S. formed of thin japanned
sheet iron; such as ferrotype-plate, and so, attached, that being wound round the
major part of the shaft; as shown in Drawing, they act as springs at that portion,
and so take off any sudden jar, or shake, that may occur at the instant, of release.
The shutters, are faced with black velvet, or other, suitable material.
The shutters, can, also, be formed of other, material, than sheet iron; still, acting
on the same principle.
The end of shaft P. that passes through the plate T. has one, portion turned
smaller; to admit of an arm, C. to work loosely, as shown in section; the end, of
shaft is screwed, and fitted with a milled-head nut; so that, when in use, and the
nut screwed down moderatly tight, on arm C. the friction, is sufficient, to work
the connecting rods, D, and O.
By the means of this loose arm, the lower shutter, can be placed in any, desired,
position; as shown by doted lines in N° 2. B, is a second arm, of proportional
length to carry the ends of connecting rods, D, and O.
The upper, end of connecting rod O. is attached by a pin to a trigger-plate; fixed
on a squared, portion, of shaft Q. and works the top shutter. The proportional;
length of centres, of pin and shaft at A. can, be varied in manufacture, to suit
the required position; the top, shutter is to remain at, when the bottom, shutter, is
closed. this is shown by doted line S¹..

page_text: The trigger plate, has two indents, formed in its circumference; one to hold the
top, shutter down. by the end, catch of trigger; the other indent, is to allow of the
back, catch of trigger, to hold at half cock, either for focusing, or to prolong the time
of exposure; at the will of the operator. and this, is manipulated; by shifting, the
lever F. up to the centre stud F. The result is, that at the moment of release, it
allows the trigger, to fly up ready to meet the second; indent. and so retain the
shutters full open, as shown in N° 2. and remains, in that position, untill, either;
the lever end of the trigger is toutched, or; the air drawn down through the
pneumatic cylinder. By either, of these means, the trigger is drawn away from the
indent, and allows the bottom shutter to close up.
The piston N. being partly, of a spherical, form. allows of a rocking, motion.
without any material loss of air, the rocking, motion being caused, by the working
of the trigger. The manipulation, of the piston and trigger, is so simple, and
easey, that; by attaching the end, of an ordinary rubber tube; of one eighth of
an inch bore, and at the other, end of tube; an ivory mouth piece. as shown in N° 1.
the breath, is sufficient to work it, either by blowing through; to lift the piston,
and release the trigger from the first indent. or by drawing the breath back, pulls
down, the piston. and releases the trigger from the second, indent. and so allows
the shutters to close. Or, a small rubber ball, of ordinary manufactor; can be
used; such as shown in N° 3. or the slight toutch of the feather end, of a quill pen,
to the end of trigger, either up or down as required.
The spring G. is to counteract by friction. and overcome, the weight of piston ;
and so prevent it pulling down the trigger, by its own weight.
The metal plate U. on opposite, side of frame, holds the mechanism, for working
the shutters; and regulating, the time of exposure. when allowed to work
automatically.
The end of the shaft P. is made square, to carry the brake-plate M, and pulley ;
which is formed as one, member. and both are turned excentric, as shown in
Drawing N° 3. The position of excentricey of pulley; can be varied, to suit the
size of shutters required; or to regulate, its action, as to speed.
The excentricy of brake-plate M. allows of the greatest, pressure of brake, at
commencement, of the movement of shutters, and as the lower, shutter rises, the
pressure falls off; and when, the shutters has arrived at the position of full open,
the stop Y. prevents the brake from further action; and allows the bottom, shutter.
to fly up and close.
The brake K. has, cemented to its face, a piece of soft leather L. The face edge,
of brake-plate, being highly polished; the leather, allows of a smooth, steady,
action.
The pressure, of spring H. upon the brake, is regulated by the excentric,
quadrant, J. and shown, by the index above, as in Drawing N° 1.
The power of movements, of the shutters, is caused, by the elastic-rubber-band
spring W, the band, is cut, and one, end, is attached to the hook on pulley M.
it is then, passed on, and travels round the roller I. and the other end, attached, to
a pin, fixed in standard X.
A watch spring, attached to the shaft. can, be substituted, for this, as a motive
power. Also, a long spiral spring. without, deviating from the principle, herein
described.
A bush of ivory or other suitable material. is inserted, in plate U. to prevent
friction, caused, by the pressure of brake.
In Drawing N° 3. is shown, the positions, taken by the lower arms, and short
connecting rod, in course of action.
Cases, of thin japanned iron, or other, suitable material, are placed on each, side-
plate to protect the mechanism, and to have inscribed on one of thein, the index
over the regulating spring.
When useing, the shutter it is attached to the lens mount, and camera, by a wire
hasp, and staple, as shown in vertical section, in Drawing N° 2.

page_text: 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 means of so combining the two lower arms C and B. and the two
connecting rods, D and O. and so cause the speed, of the two shutters, in relation
to each other, to be so altered, that a first slow movement of the bottom shutter,
causes, a first rapid movement of the upper shutter, ending, with a slow, movement.
and thus, forming a sky shade. at the same time, the lower, shutter, is increasing, in
speed; and when fully, opened, flies up, and closes. this is done by the form of the
lower, connecting rod D.
2nd The form of arm C. the shank, being bored to fit loose, up to shoulder, of
shaft P. the screwed end, and milled-nut, on shaft, in combination; which allows
the bottom, shutter, to be placed, in any, desired position.
3rd The form, and application, of arm B. which allows, of the use of two;
connecting rods, in combination.
4th The form, and application of the trigger plate A. carrying the end, of
connecting rod O. and admitting of two indents.
5th The form and application of the trigger, E, check lever F, and spring G. in
connection therewith.
6th The partly, spherical, form, of piston N. which allows of a rocking,
movement, without material loss, of air in cylinder.
7th The manner of fixing to, and partly winding, the fixed ends of shutters, S. S.
round, the shafts. to cause that portion, of the shutters to act as springs, and so
take off, any sudden, jar or shake, caused, by their sudden movements.
8th The excentric, form. and use of the brake-plate, and pulley, M. the form
and application of brake K. with its leather facing L.
9th The use, and application, of spring H. to give pressure to the brake.
10th The form and application, of excentric, quadrant, J. to regulate the
pressure, of spring H. with its index, to notify; the amount of pressure, or
approximate time of action.
11th The manner of applying, the elastic rubber-band W. to act as a main
spring.
12th The means and manner of employing, and useing, thin japanned sheet iron.
as flaps, or shutters; substantially, as shown in Drawing, and herein described.
Dated this 14th day of May 1884.
THOMAS FURNELL.