Year: 1888

page_text: Date of Application, 9th Nov., 1888
Complete Specification Left, 28th Dec., 1888
Complete Specification Accepted, 29th Jan., 1889
1, JAMES LYON Engineering Department Cambridge University, do hereby declare
the nature of this invention to be as follows:-
A photographic shutter for photographing rapidly moving objects.
This shutter opens the lens gradually, it then leaves the lens fully open for a much
longer time than was occupied in opening it and it finally closes the lens gradually,
in a time nearly the same as that taken to open it.
However short the whole time the lens is wholly, or partially uncovered, the ratio
of the time that the lens is fully open to the time taken in opening and shutting the
lens, is large.
The object of the shutter is to give the largest possible amount of light to the
sensitive plate during any given time of exposure of the plate to light entering the
camera through the lens.
The movements of the two leaves which form the covering to the lens are effected
by a disc having in it two pins each of which operates a leaf. The pins work in two
slots, cut in two sheets of metal called sliders, the slots being so shaped that when the
disc revolves the sliders move through a certain distance; the pins then arrive at
a portion of the slots, which are concentric with the centre of rotation of the disc, and
therefore the pins move through portions of their paths without moving the sliders;
the pins then arrive at portions of the slots which are so shaped that the sliders are
moved in the contrary directions.
The movements of the sliders are multiplied in the leaves by means of levers or
otherwise The disc is made to rotate by means of a suitable spring and the exposure
is effected by releasing the disc by means of a catch operated by a pneumatic cylinder
or otherwise-The momenta of the working parts are so adjusted as not to shake
the camera.
D
1 1.
L J
1000

page_text: I, JAMES LYON, Engineering Department Cambridge, Superintendent of the
Engineering Department Cambridge University 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 means of opening and closing the shutter for the lens of a
photographic camera in such a manner that this operation may be almost instanteously
effected as is required when rapidly moving objects are photographed but that, whether
the whole time in effecting it be short or long, the portions of the time occupied in the
movements of the shutter for opening and closing hear a small ratio to that portion of
the time during which the lens remains uncovered. For this purpose I employ a
shutter movement such as is represented diagrammatically by the accompanying
drawing shewing the lens A covered by two shutters B and C arranged to slide to
and fro in opposite directions, meeting in the middle of the lens when it is covered,
and drawn apart sufficiently far to uncover it completely.
In order to effect this movement I mount on an axis a disc. D having two
diametrically opposite crank pins E and F engaged respectively in curved slots of two
sliding frames G and H both of which are guided at 1. The frame G has two arms
jointed to a pair of levers near their fulcra K K, the long arms of the levers being
jointed at L'to the shutter C. In like manner the frame H has two arms jointed to
levers working on the fulcra K K and having their long arms jointed at M to one end
of the frame which carries at its other end the shutter B.
The jointings of the levers to the arms of G and H and to the pins L and M are
suitably slotted to allow for the movements of the levers in circular paths while the
arms and the shutters move rectilineally.
The curved slots of G and II in which the crank pins E and F are engaged are
made each for a short distance at its starting end N concentric with the axis of the
dise D, then with a short inwards slope O then after being again for most of their
length concentric, terminating in an outward slope P.
The disc D having been turned in opposition to a volute or other suitable spring, is
held by a catch in the position shewn keeping the shutters B and C closed over the
lens. When a photograph is to be taken the catch of D is released and the spring
causes D to make a partial revolution more or less rapidly as determined by the tension
of the spring, which may be adjusted as desired.
During the first part of the revolution of D the crank pins E and F, moving in the
concentric parts N of the slots, give no movement to the shutters, but, allow time for
the disc to acquire velocity. The pins then acting in the sloped parts O give move-
ment right and left to the frames G and H, and these through the levers to which
they are jointed give very rapid motion to the pins Land M so as to withdraw the
shutters C and B. While the crank pins E and F move through the comparatively
"

page_text: long concentric parts of the slots, the shutters are held open, and it is not until the
pins act on the slopes P that the shutters are closed by a rapid movement corre-
sponding to that by which they were opened.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
In combination with the lens shutters of a photographic camera a spring moved
crank disc having crank pins working in curved slots of sliding frames connected by
multiplying levers to the shutters, substantially as and for the purpose herein
set forth.
ABEL & IMRAY,
Agents for the Applicant.