Year: 1888

page_text: Date of Application, 14th June, 1888
Specification Accepted, 20th July, 1888
I, WALTER PEAD, of 99, High Street, Ramsgate, in the county of Kent, Book-
binder, 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 :--
My invention relates to an instantaneous shutter for use in connection with photo-
graphic lenses, and it comprises the improvements hereinafter described.
In the accompanying drawing
Figure 1 is an elevation of my improved shutter the parts being in the position
which they occupy previous to exposing a plate.
Figure 2 is an elevation of the opposite side of the shutter from that shown in
Figure 1, the parts being in the position which they occupy after operation.
Figure 3 is an edge view of the shutter.
Figures 4 and 5 are views of different parts of the shutter,
Figure 6 is a section on the line x, x Figure 4.
and
a is a diaphragm which is arranged between the lenses of a camera in the same
manner as an ordinary diaphragm and which has double walls so as to leave between
the same a slot or guide b, as shown in Figure 6.
c is a plate fitted into the slot b and adapted to slide therein, the said plate having
an aperture d of sufficient size to allow the passage of the rays of light through the
opening e of the diaphragm when the said aperture and opening coincide or are
opposite to one another during the movement of the plate or slide from the position
shown in Figure 1 to that shown in Figure 2.
fis a spring catch the free end of which is designed to engage in the hole g in
the slide c when the latter is in its raised position ready for operation as shown
in Figure 1.
h is a lever pivotted to the diaphragm and extending between the said catch and
the wall of the diaphragm so that when the said lever is moved from the position
shown in Figure 4 to that shown in Figure 2, the end of the catch will be drawn out
of the hole g.
i is an india-rubber or elastic spring which is attached to hooks j, j at the edges of
the diaphragm and passes over a hook k on the upper end of the slide c, as shown in

page_text: Figure 1, so that when the catch is withdrawn as hereinbefore described the slide c
will move to the position indicated in Figure 2. Instead of the catch f and spring i
herein before referred to any other suitable means may be employed for releasing the
slide and moving the same.
1 is a flange which serves to maintain the diaphragm in its proper position in the
slit and to prevent the entrance of light through the said slit.
In using my improved shutter the plate is raised so that the catch f engages in the
hole and when the catch is withdrawn the slide is drawn down under the action
of the spring i, the sensitized photograph plate being exposed during the time that
the aperture d is passing before the opening e of the diaphragm. If a longer exposure
is desired than it is possible to obtain when the spring is used, the latter may be
dispensed with and the slide operated by hand.
Instead of forming the diaphragm with double walls a single plate having guides
on one side for the slide may be employed.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The combination with a diaphragm adapted to be inserted between the lenses of
a photographic camera of a plate capable of sliding in or upon the said diaphragm,
substantially as, and for the purpose described.
2. An instantaneous shutter comprising a diaphragm having double walls and a
plate sliding between the same, substantially as described.
3. The improved instantaneous shutter constructed and arranged to operate
substantially as hereinbefore described and as illustrated in the accompanying
drawing.
Dated the 14th day of June 1888.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.