Improvements in what are known as Instantaneous Photographic Shutters.
Year: 1887

page_text: Date of Application, 22nd Apr., 1887
Complete Left, 21st Jan., 1888
Complete Accepted, 20th Apr., 1888
INUYIDIONAL DILUIFICATION.
Improvements in what are known as Instantaneous Photographic
Shutters.
Wo, THOMAS RUDOLPH DALLMEYER of 19 Bloomsbury Street in the County of
Middlesex, Optician and FRANCIS BEAUCHAMP of High Cross, Tottenham in the
County of Middlesex, Engineer do hereby declare the nature of this invention to be
as follows:-
Photographic shutters as at present made usually move across the lens.
According to this invention the shutter commences to open at the centre the opening
being always approximately a circle the size of which increases till the shutter is fully
open when it diminishes until the shutter is again closed the driving part or parts con-
tinuing to move all the time in the same direction without any corresponding reversal.
The shutter is formed of several (say four) segments of a sickle or chopper liko
form which, when the shutter is closed, overlap each other and when the shutter is
open leave a roughly circular opening. These segments are pivoted to an annular plate
and they carry pins by which the necessary movements are cominunicated to them.
These movements may be given by a second annular plate provided with cam grooves
cut in it, one for the pin on each segment. The cam grooves are of an angular form
so that the rotation of the plate in which they are formed at first opens the shutter
to its full extent and then (the plate continuing to rotate in the same direction) closes
the shutter or in place of having all the cam grooves in the annular plate some or all
of them may be formed in the segments in which latter case the second annular plate
is dispensed with, the tail of one of the segments being furnished with a lever by
which it and with it the other segments is actuated. In this case in order to obtain
the desired continuity of movement of the driving part a crank or suitable cam
groove must be provided to give the necessary to and fro movement to the lever.
The lense tube is made in one piece a slot being made in it for each segment of the
shutter an arrangement which gives great strength and ensures the glasses of the
lense remaining at their proper distances apart.
The
power for opening and closing the shutter may be given by a spring retained
by a trigger in any convenient or well known way.
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T.
1007

page_text: We, THOMAS RUDOLPH DALLMEYER of 19 Bloomsbury Street, in the County of
Middlesex, Optician and FRANCIS BEAUCHAMP of High Cross, Tottenham in the
County of Middlesex, Engineer 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 :—
Photographic shutters as at present made usually move across the lens either in
front or behind the combination or combinations, or if between the combinations, in
order to obtain full exposure of lens, it has hitherto been necessary to entirely sever
the lens mount.
According to this invention the shutter commences to open at the centre the
opening being always approximately a circle the size of which increases till the
shutter is fully open when it diminishes until the shutter is again closed the driving
part or parts continuing to move all the time in the same direction without any
corresponding reversal.
The shutter is formed of several segments of a sickle or chopper like form which,
when the shutter is closed, overlap each other and when the shutter is open leave a
roughly circular opening. These segments are pivotted to an annular plate and they
carry pins by which the necessary movements are communicated to them. These
movements may be given by a second annular plate provided with cam grooves cut
in it, one for the pin on each segment. The cani grooves are of an angular form so
that the rotation of the plate in which they are formed at first opens the shutter to its
full extent and then (the plate continuing to rotate in the same direction) closes the
shutter or in place of having all the cam grooves in the annular plate some or all of
them may be formed in the segments in which latter case the second annular plate is
dispensed with, the tail of one of the segments being furnished with a lever by which
and with it the other segments is actuated. In this caso in order to obtain the
desired continuity of movement of the driving part a crank or suitable cam groove
must be provided to give the necessary to and fro movement to the lever.
The lens tube is made in one piece a slot being made in it for each segment of the
shutter an arrangement which gives great strength and ensures the glasses of the
lens remaining at their proper distances apart.
The power for opening and closing the shutter may be given by a spring retained
by a trigger in any convenient or well known way.
In order that my said invention may be most fully understood and readily carried
into effect I will proceed to describe the drawings hereunto annexed.

page_text: Figure 3 is a front view with the front plate and lever and also the cam plato
removed.
In these three figures the dotted circle shows the full opening of the shutter.
Figure 4 is a plan partly in section.
Figure 5 is a longitudinal section of the tube.
Figures 6 and 7 are an edge view and plan of one of the segments.
a a are the segments of the shutter, each being of a sickle or chopper-like form, as
shown in figure 7. They are pivoted at 66 to an annular plate c, and they carry
pins dd which enter grooves in the cam plate e. The plate e carries a
pin f, which
passes through a slot in the cover-plate g. The pin ƒ enters a slot in the lever h, so
that, by moving the lever h, the cam plate e is turned and the pins d are thereby
forced first away from the centre and then back again by reason of the form of the
slots in the cam plate e, the shutter is therefore first completely opened and then, by
the continuation of the same movement of the cam plate, is again closed.
Figures 8, 9 and 10 shew a modification of this arrangement. In this case the
cam plate is omitted, the pins on the segments entering slots in the other segments.
Figure 8 is a front view of the shutter when fully open, the front plate being
removed.
Figure 9 is a transverse section of the same, and
Figures 10 are plans of the four shutters.
1, 2, 3, 4, are four shutters pivotted at 1, 12, 13, 1, to the annular plate c;
they are actuated by a lever m fixed to the segment. The segment carries
a pin 2 which enters a slot in the segment k¹, and similarly the segments
carry pins n³n, which enter slots in the segments, ². The lever m is slotted at m¹
and this slot receives the crank pin o¹ upon the crank o. As the crank turns the lever m
has a to and fro motion given to it, as shown it is in its central position, the shutter
being fully open. The crank o is actuated by a spiral spring in the barrel P, which
carries a projection p' which is retained by a catch When the catch is freed the
spring causes the crank o to revolve and thereby moves the lever m to and fro, and
so first
opens the shutter and then closes it again.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim
is
1. Photographic shutters which open from and close towards the centre, the
opening being always of a roughly circular form substantially as described.
2. Photographic shutters opening from and closing towards the centre, which are
first opened and then closed by the continuous movement of the driving-parts in one
direction substantially as described.
3. Photographic shutters consisting of three or more segments which, when the
shutter is closed, overlap one another and are of such a form that the central opening
is always of a roughly circular formn, substantially as described.
4. The lens tube made in one piece with slots for the segments of the shutter
substantially as described.
5. Photographic shutters substantially as described and shown in figures 1 to 7.
6. Photographic shutters substantially as described and shown in figures 8 to 10.
7. Improvements in what are known as instantaneous photographic shutters
substantially as described.
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THOS. R. DALLMEYER.
F. BEAUCHAMP.