Improvements in Shutters for Photographic Cameras.
Year: 1889

page_text: Date of Application, 16th Mar., 1889
Complete Specification Left, 16th Dec., 1889-Accepted, 1st Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in Shutters for Photographic Cameras.
We THOMAS WRIGHT GREENALL of The Grammar School, Hartlebury, near Kidder-
minster, Clerk in Holy Orders, and FRANK BISHOP of the Firm of Marion & Co. of
22 and 23 Soho Square, in the County of Middlesex, Dealers in Photographic
Materials &c. do hereby declare the nature of this invention to be as follows :-
-
This invention relates to an improved so called "Instantaneous" shutter for
photographic lenses. The shutter is of that kind which opens and closes upon a
diametrical line by the motion in opposite directions from the centre to the sides, of
a pair of plates or wings pivoted upon a common centre and overlapping when
closed.
The invention relates essentially to the mechanism whereby the plates or wings
are operated, and the object of the invention is to simplify this mechanism and
reduce the cost of manufacture. The plates or wings are operated by a pin moving
in a curved angular or bi-angular slot in each of them, the slots lying in a direction
such that the two extremities of each slot are in a line about radial to the centre of
motion of the plate or wing and the slots being oppositely bent or curved so that
motion of the pin from one end to the other of the two slots will cause simultaneous
motion of the two plates or wings in opposite directions, the motion of the pin
through the first half of the slots causing an outward separating or opening motion
of the plates and the motion of the pin through the second half of the slots causing
an inward or closing motion of the plates. This actuating pin is carried or actuated
by a lever pivoted to the frame and acted on by a spring provided with means of
varying its tension for the purpose of regulating the velocity of motion of the plates
according to the length of exposure required, a spring trigger being also provided
having notches or shoulders adapted to engage with the lever and hold the plates
either in the closed or open position as required, said trigger being released either
directly by hand or by pneumatic agency, as well understood. The pin through
which the plates are actuated, projects through a slot in the frame and serves as the
medium through which the shutter may be brought to the open position for focussing
for a prolonged exposure or
::set " for a short or "instantaneous exposure.
Daten [HIS 1040 03Y OF March
LOOD.
Daten [IS TOLD OHY 01 March LOON.
T. W. GREENALL
F. BISHOP.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Shutters for Photographic Cameras.
We, THOMAS WRIGHT GREENALL, of The Grammar School, Hartlebury, near Kidder-
minster, Clerk in Holy Orders, and FRANK BISHOP of the firm of Marion & Co., of
22 and 23, Soho Spuare, in the County of Middlesex, Dealers in Photographic
Materials, &c., do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This Invention relates to an improved photographic lens shutter of that kind which
opens and closes upon a diametrical line by the motion in opposite directions of a
pair of plates or wings pivoted upon a common centre and overlapping when
laced

page_text: The Invention relates essentially to the mechanism whereby the plates or wings
constituting the shutter, are operated; and the object of the invention is to simplify
this mechanism and reduce the cost of manufacture.
Reference is to be had to the accompanying drawings, forming part of this
specification, wherein figure 1 represents a face view of the improved shutter, the
cover plate of the casing being removed and the shutter being set in position for a
very short or instantaneous exposure; Figúre 2 is a similar view, the shutter
being in the open position for focussing the picture; and figure 3 is a face view
with the cover applied, the shutter being in the open position for a prolonged
exposure. The same letters of reference indicate like parts in all the figures.
A, B, are the two plates of thin vulcanite pivoted on a common centre a and
working in slots in the casing C which is provided with an aperture D which the
plates are adapted to close and which corresponds to the aperture of the lens tube
to which the casing is adapted to be affixed in any ordinary way. The inner edges
of the plates overlap slightly when in the closed position, as shewn in figure 1, and
the shutter opens and closes on a diameter 1-1 of the aperture D by simultaneous
motion in opposite directions of the plates A, B, about their centre a.
The plates A, B, are operated by a pine traversing both plates and moving in
curved or angular slots f, g, one in each of the plates the slots being oppositely
bent or curved and lying across each other in such a direction that motion of the
pin from one end to the other of the two slots will cause simultaneous motion of
the two plates in opposite directions the motion of the pin through the first half of
the slots causing an outward separating or opening motion of the plates and the
motion of the pin through the second half of the slots causing an inward or closing
motion of the plates. The first half of each slot i.e. that nearest to the centre a, is
preferably straight whilst the second half is curved, as shewn, but the form of the
slots may be varied without materially altering the operation.
The pin e is carried or actuated by a lever E pivoted to the frame C and acted
on by a spring G provided with a pressure screw or other means of varying its
tension for the purpose of regulating the velocity of motion of the plates. A
spring trigger H is also pivoted to the frame and has notches or shoulders h¹ ª
adapted to engage with the free end of the lever E to hold the shutter either in the
"set" position, shewn in figure 1, or in the open position, as shewn in figure 2,
said trigger being released either by hand or by an ordinary pneumatic con-
trivance I as well understood. The pin e projects through a slot c in the cover plate
of the frame and serves as the medium through which the shutter may be brought to
the open position for focussing "set" for a short or "instantaneous" exposure or
arrested in the open position for a prolonged exposure. For the last mentioned
purpose a lever K is pivoted to the cover plate in position to be swung across the
slot c into the path of the pin e. It is formed with a bevelled catch k at its lower
end which is brought into position to arrest the pin e, as shewn in full lines in
figure 3, by the trigger H bearing against 'à stud k at the tail end of the lever K.
For making a prolonged exposure therefore, the lever K is adjusted in position to
be so acted on by the trigger and the shutter is "set," as in figure 1.
When the
trigger is moved so as to release the lever E, the shutter opens as for a short
exposure but, by the further motion of the trigger in the same direction, the shutter
is arrested; when full open, by the lever K obstructing the pin e, as in figure 3,
and remains open so long as the bellows I is kept distended. When the pneumatic
pressure is relaxed the lever yields and the shutter is closed by the power of the
spring. For short exposures, the lever K is moved out of action, as shewn in dotted
lines in figure 3.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim'is;

page_text: pivoted plates A, B, having the oppositely bent slots in them, as described, of
mechanism, substantially as herein specified, for operating said plates and for
retaining them in the various positions described.
Dated this 16th day of December 1880
T. W. GREENALL.
F. BISHOP.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents