Improvements in Iris Diaphragms for Photographic or other •
Year: 1894

page_text: Date of Application, 7th Mar., 1894-Accepted, 28th Apr., 1894
COMPLETE SPECIFICATION.
Improvements in Iris Diaphragms for Photographic or other
•
⚫ Purposes.
We THOMAS MORTON, of 405 Lodge Road, in the City of Birmingham,
Toolmaker, and JOHN AMBROSE SPRASON, of Saint George's Place, Great
Hampton Row, in the City of Birmingham, Brassworker, 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 the manufacture of what are known as iris diaphragms,
which are generally employed in photography, but which are sometimes used for
other purposes.
These iris diaphragms briefly consist of an annular shaped shell within which is
a part rotating ring, which, in its motion open and close a number of leaves, so
as to concentrically open or close the central opening. It is to the method and
means used for securing these leaves to their plate or ring (moveable or fixed)
that this our invention has more particular reference.
In usual practice the holes in the rings or plates to which these leaves are
attached, are drilled separately and consequently, lack of precision in their exact
equidistant position creeps in, and consequently very great care and skill has to
be exercised in their manufacture which necessarily entails much expense and
trouble. It is therefore principally to this that we have directed our invention.
In order to more clearly describe and explain this our said invention, we have
appended hereunto an illustrative sheet of drawings, upon which are figures and
numbers of reference, similar numbers referring throughout the several views to
the same thing or part. In these drawings we have shown the whole building up
of a diaphragm so that the full adaptation of our invention may be seen.
Figs. 1 to 10, show variously the details of this our invention, or of its
application.
Figs. 11 to 15, illustrate a completed diaphragm made according to this our
invention.
16, which is then
shown in Fig. 2.
In these tools a
We proceed as follows:-We cut out an annular ring blank
subjected to tools 17 & 18, (or other similar suitable tools) as
This Fig. 2, being a cross sectional view through their centre.
number of equidistant holes or recesses 19, are made according to the number of
pegs or fixed rivets required in the ring. These tools are now submitted to
considerable pressure (as seen in Fig. 3) so that the metal of the blank 16, is
compressed until a portion of it is forced into the holes 19, so that when removed
from the die 18, the ring 16", has a corresponding number of pegs or rivets 20,
upon its surface, which are solid therewith. It will be therefore seen that in this
manner the exact relative position of all the pegs 20, is absolutely fixed, so that
great care and skill has to be exercised but once, that is, in the production of the
dies.
Having now made the plate 16ª, (Figs. 4 & 5), we next prepare the leaves 21,
as seen in Figs. 6 & 7, having at the one end the hole 22, and at the other end, the
peg or stud 23. A. given number of these leaves are now passed on to the pegs of
the ring 16, as seen in Fig. 8, and rivetted over, but capable of easily being
turned about such pegs. By reason of having these pegs 20 formed thus solid
with the plate, it better enables us to use thinner leaves than it would be if the
rivets or pegs were separate. This is an advantage because when these diaphragms
are used in photography, it is desirable that the leaves should lie as close as

page_text: possible to each other, and avoid intermediate or dividing space as much as possible
to prevent admission of light.
We now cut out the plate 24 (Fig. 9) having the slots 25 which are shown
angular, but may be otherwise as most convenient. We next provide the case
or shell 26, (Fig. 10) to receive the various parts, and having a slot or opening 27,
see Fig. 13, in which may work the arm 28. On reference to Fig. 11, it will be
seen that the plate 24 is placed in the bottom of the shell, then the plate 16"
having the leaves 21 attached thereto is invertedly passed into the recess 29, with
the pegs 23 respectively engaging with or into the slots 25 of the plate 24; these
leaves 21, in the Fig. 11, being represented by a dotted line. The edge of the
shell at 30, is now turned down and closed over the plate 16ª, thereby securing it
firmly in position so as also to prevent rotation. By now part rotating the arm 28,
the leaves are opened and closed in the well known manner as seen in Figs. 14 & 15,
the central opening in Fig. 15, being so much smaller than in Fig. 14, while in
Fig. 12, the arm is turned round until the leaves are all concealed in the shell, and
the centre full opened.
If desired in some cases we may vary the position of these solid pegs, that is,
they may be similarly formed upon the moving plate 24, and the slots 25 be formed
upon the fixed plate 16", as may be most convenient.
We wish it to be understood that we are aware iris diaphragms are not new and
that we have shown the full construction of one in order to show the application
of our invention, and that we do not confine our invention to the particular or any
shape of diaphragm, but,
Having now particularly described and ascertained the nature of this our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
:-
The method of connecting the leaves of a diaphragm such as that herein
described, which consists in making the pegs or rivets 20, in one solid piece with
their plate 16ª, or other plate upon which it may be desired to form them, as
described and shown.
Dated this 6th day of March 1894.
CHARLES T. POWELL,
Applicants' Agent.