Year: 1888

page_text: Date of Application, 16th Apr., 1888
Complete Specification Left, 19th Oct., 1888
Complete Specification Accepted, 23rd Nov., 1888
RESERVE
We, THOMAS RUDOLPH DALLMEYER, of 25 Newman Street, Oxford Street, London,
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:-
This invention relates to improvements in photographic lens shutters of the kind
referred to in the Provisional Specifications filed with our applications for Letters
Patent on the 22nd day of April 1887, No. 5903, and on the 16th day of June 1887
No. 8711.
The photographic lens shutters referred to in the specifications of the abovenamed
patents are usually composed of several leaves, or chopper-shaped pieces turning
simultaneously on centres or pins in such manner as to form, by the intersection of
their inner edges, a larger or smaller aperture in the lens mount. When it is required
to expose the prepared plate to the action of light the shutter is opened and shut by
hand or by suitable mechanism within the required time; but by the arrangements
heretofore in use the shutter has been opened to its full extent for each exposure
whether such exposure be long or short, and the amount of light admitted to the plate
has been regulated by a diaphragm or stop, having a hole of suitable size and placed
in front of the shutter. The object of this invention is to obviate the necessity of
employing a diaphragm or stop in front of the shutter, by so arranging the mechanism
by which the shutter is opened and closed, that instead of the shutter being opened to
its full extent for all exposures, the said mechanism can be so regulated that the shutter
is opened only to an extent corresponding to the proper size of aperture that would
be used if the ordinary diaphragm were employed, whereby such diaphragm is
dispensed with and the shutter serves the purpose not only of a shutter but of a
diaphragm as well.
For this purpose we secure on the lens mount mechanism of the following character
connected with and operating the lever arm by which the leaves or chopper-shaped
pieces, forming the shutter, are actuated.
The aforesaid actuating lever arm is slotted in the usual way, and a crank pin
mounted on or connected with a spring barrel takes into the slot in the said arm.

page_text: The spring barrel with its crank pin can be adjusted on the lens mount so that the said
crank pin can impart a greater or lesser amount of motion to the actuating lever arm
according as it is required to open the shutter more or less, or the same effect may be
obtained by making the crank pin adjustable radially whereby its stroke or throw can
be varied according to the required opening of the shutter. The spring barrel contains
a coiled spring which can be wound up by means of a key or button in the usual way,
and is retained in its wound up position by means of a ratchet wheel and pawl. When
the pawl is disengaged from the ratchet wheel the spring rotates the barrel and the
crank pin opens the shutter to the extent permitted by the adjustment and closes it
again. Suitable means are provided for holding the shutter open to the required
extent when it is desired to give a comparatively long exposure.
In some cases it is required to open the shutter, and to hold it open a definite time,
in order to obtain a longer exposure than can be obtained by the opening and closing
of the shutter by the unrestrained action of the crank pin operated by the spring
barrel;
for this purpose there is connected, directly or indirectly, to the ratchet wheel
by which the barrel is prevented from rotating, a disc or plate having in its edge a
single notch; a releasing lever or trigger is so arranged that a catch on the said
lever or trigger is capable of engaging with the teeth of the ratchet wheel, and
another catch on the said lever or trigger with the notch on the edge of the disc or
plate, but so that when the one catch is engaged in the teeth of the ratchet wheel the
other catch is held away from, and cannot engage in the notch of the disc or plate,
whilst when the one catch is disengaged from the teeth of the ratchet wheel the other
catch bears against the edge of the disc or plate, and is free to enter the notch therein.
It will now be understood that when the catch is drawn out of the teeth of the ratchet
wheel the barrel and crank pin begin to revolve, and effect the opening of the shutter
to the required extent; when that is effected the notch in the disc or plate comes
opposite the second catch on the liberating lever, and the said catch enters the said
notch, arresting the further motion of the barrel and crank pin, and holding the shutter
open until the operator judges that the exposure is sufficient, when he moves the lever
or trigger so as to withdraw the catch from the notch in the disc, and holds the other
catch free of the teeth of the ratchet wheel, when the barrel and crank pin complete
their motion and close the shutter.
In some cases it is sufficient, in order to obtain the necessary exposure, to retard the
action of the barrel and crank pin; for this purpose we employ a friction brake con-
nected either directly or indirectly with the spring barrel. The friction of this brake
may be increased or decreased at pleasure by an adjusting screw or otherwise, so that
by increasing the friction the spring barrel will occupy a longer time in effecting the
motion of the shutter, and by decreasing the friction the barrel will occupy a shorter
time in effecting such motion. The adjusting screw may be provided with an index
finger for indicating the amount of tension put on the brake by the screw, and thereby
inferentially, the speed at which the opening and closing of the shutter will be
effected.
Data: 1011
^
11000

page_text: Improvements in Photographic Lens Shutters.
We, THOMAS RUDOLPH DALLMEYER, of 25 Newman Street, Oxford Street, London,
Optician, and FRANCIS BEAUCHAMP, of High Cross, Tottenham, in the County of
Middlesex, Engineer, do hereby declare the nature of the said invention, and in
what manner the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accompanying three
sheets of Drawings, and to the letters and figures marked thereon that is to say :-
This invention relates to improvements in photographic lens shutters of the kind
referred to in the specifications of Letters Patent granted to us bearing date
respectively the 22nd day of April 1887, No. 5903, and the 16th day of June 1887,
No. 8711.
The photographic lens shutters referred to in the specifications of the abovenamed
patents are usually composed of several leaves or chopper shaped pieces turning
simultaneously on centres or pins. When it is required to expose the prepared plate
to the action of light the shutter is opened and shut by hand, or by suitable mechanism,
within the required time; but by the arrangements heretofore in use the shutter has
been opened to the full extent for each exposure, whether such exposure be long or
short; and the amount of light admitted to the plate has been regulated by a
diaphragm or stop having a hole of suitable size, and placed in front of the shutter.
The object of our present invention is to obviate the necessity of employing a
diaphragm or stop in front of the shutter, by so arranging the mechanism, by which
the shutter is opened and closed, that instead of the shutter being opened to the full
extent for all exposures, the said mechanism can be so regulated that the shutter is
opened only to an extent corresponding to the proper size of aperture that would be
used if the ordinary diaphragm were employed, whereby such diaphragm is dispensed
with, and the shutter serves the purpose not only of a shutter but of a diaphragın
as well.
For this purpose we secure on the lens mount mechanism of the following character
connected with, and operating the lever arm by which the leaves or chopped shaped
pieces forming the shutters are actuated-The aforesaid actuating lever arm is
slotted in the usual way, and a crank pin, mounted on, or connected with a spring
barrel or with a spring-actuated axis takes into the slot in the said arm.
The spring
barrel or the spring-actuated axis with the crank pin can be adjusted on
the lens mount, so that the said crank pin can impart à greater or lesser amount
of motion to the actuating lever arm according as it is required to open the
shutter more
or less. Or the same effect may be obtained by making the crank
pin adjustable radially in its crank whereby its stroke or throw can be varied
according to the required opening of the shutter.
The Drawings hereto annexed illustrate these arrangements as applied to lens
mounts having shutters of the kind described in the specifications of the above.
mentioned patents No. 5903 and 8711. Figure 1 is a side view of part of such a'

page_text: lens mount, Figure 2 is a longitudinal section of same taken on line 1-1 of Figure 1,
Figure 3 is an elevation of the circular box containing the shutter-mechanism with
the cover and tube A, seen in Figure 2, removed, the shutter being shown wide
open. Figure 4 is an elevation with the cover C and tube A in place the shutter
being shown about midway between the full open and quite closed position; Figure 5
is a similar view with the shutter completely closed. Figures 6, 7 and 8 are detail
views, to a larger scale, of the mechanism for actuating the shutters.
A represents part of the tube of the lens mount, B a circular box or chamber at
the end of the tube A, containing the shutter. C is the cover of the said box B.
A is a tube formed with, or secured in the centre of the cover C, and forming a
prolongation of the tube A. DD are the metallic leaves or chopper-shaped pieces
which together form the shutter. These leaves turn respectively on fulcrum pins D¹
in the back of the box B, and carry pins D2 which take into slots K in a ring J fitting
casily into, and turning, to a limited extent, in the box B. L is a slotted lever arm
projecting from the ring J through an opening in the side of the box B. By turning
the ring J in the direction of the arrow in Figure 3 by means of the arm L the sides
of the slots K in the ring J press against the pins D2, causing the corresponding
leaves D to turn inwards on their fulcrum pins D', so that the inner segmental edges
of such leaves intersect each other in such a manner as to form an opening which
gradually decreases in size as the arm L is moved, but which is always concentric or
symmetrical with regard to the centre, and approximates more or less to the circular
form. When the arm L is moved in the opposite direction the opposite sides of the
slots K act on the pins D² so as to turn the leaves in the opposite direction, and thereby
to form a gradually enlarging opening.
The apparatus so far described in reference to Figures 1 to 5 is substantially similar
to apparatus described in the specification of our abovementioned patent No. 5903
of 1887 and forms no part of our present invention, and is only shown and described
in order to make clear the action of the automatic opening and closing apparatus
shown at the upper part of Figures 1, 3, 4 and 5 and detached, and to a scale twice
as large in Figures 6, 7 and 8. Figure 6 is a cross sectional elevation, Figure 7 is an
clevation with the cover of the containing case removed, and Figure 8 is a front view.
M is a case secured by a flange M to the back of the box B. N is an ordinary spiral
spring, one end of which is connected to the arbor N* and the other end to the case M.
This arbor N carries a spur wheel N₁, gearing with a pinion N2 on an arbor N³
having a milled handle N external to the case M. The arbor N³ has secured on it the
ratchet wheel N which is prevented from turning by the spring pawl O. P is a crank
arm external to the case and fixed on the arbor N*. The crank pin P¹ of this
crank takes into the slot L' of the arm L and is adjustable into any position in the
slot of the crank P by means of the clamping nut P³ whereby its throw or stroke
may be increased or reduced at pleasure, and thereby the distance to which the arın L
is moved towards the left in Figures 3, 4 and 5, and consequently the amount to which
the shutter D is opened, while the complete closing of the shutter is effected whatever
be the position of the crank pin P in the crank arm P as shown in Figure 5. By
turning the milled handle N the arbor N* may be turned partly round, winding up
the spring N,and turning the crank P and crank pin P1 into the upper position shown
in dotted lines in Figure 5 diametrically opposite to the lower position shown partly
in full lines in that figure, the shutter being closed as shown. The spring pawl
holds the arbor N* and crank P in that position by means of the ratchet wheel N³,
until it is required to open and close the shutter to give the needful exposure. Then,
by pressing the pawl O out of gear with the ratchet wheel N the arbor N* is released
to the action of its spring N which causes it to make a partial revolution bringing
the crank P back into the lower position shown in Figure 5. When the crank pin Pi
is adjusted towards the outer end of the crank P, and passes from its upper position
into that shown in Figure 3 causes the arm L to move from the position shown in
Figure 5 into that shown in Figure 3, that is to open the shutter to its full extent.
Then the further movement of the crank pin P¹ into the lower position, shown in
Figure 5, causes the arm L to move back from the position shown in Figure 3 to

page_text: USICA
gure, GIS to Close the Shutter again.
is a stop to prevent
the crank P from going beyond the lower position shown in Figure 5. Thus the
half revolution of the crank P causes the shutter to open to its full extent and then
to close. When it is desired that the shutter shall not open to its full extent the
crank pin P is adjusted to such a position in the crank P that its half revolution
will cause the lever L to open the shutter to the required extent; for example in
Figure the crank pin P is shown adjusted so as to open the shutter to about one
half its full opening. Whatever position the crank pin P1 is adjusted to in the
crank P the latter always returns to its lower position as in full lines in Figure 5
so as to effect the complete closure of the shutter. By these means the shutter is
made to serve the double purpose of a shutter and of a diaphragm or stop with
variable size of aperture.
Figures 9 to 15 illustrate a somewhat different arrangement for effecting the same
object. Figure 9 is an end view of a lens mount similar to that illustrated in Figures 1
to 5 showing the shutter closed. Figure 1 is a partial plan of Figure 9 and Figures 12
to 1 inclusive are detail views, to a larger scale, of the apparatus for actuating the
shutter, regulating the time of exposure and for holding the shutter open when
necessary. Similar letters of reference relate to like parts in all the Figures of the
Drawings.
The extent to which the shutter is opened is regulated in the following way;-M is
the case containing clockwork arrangements which actuate a crank pin P in a manner
somewhat similar to that already described in reference to Figures 1 to 8. This crank
pin passes through the semicircular slot Px in the side of the case M, and takes into
the slot L' in the arm L. The case M is adjustable circumferentially, to a limited
extent, on the box B by means of the tangent screw W gearing into teeth on the
edge of the flange M' of the case M, and turning in bearings W₁ fixed on the
edge of the box B. The flange M¹ is guided by screws M² M³ passing through
slots M, and can be clamped in place by the milled screw M. In the position shown
in Figure 9 the crank pin is free to make a complete half revolution in the slot P<,
and therefore to move the arm L to the left in the Figure sufficiently to open the
shutter to its fullest extent; but if the case M be moved to the right in Figure 9 the
crank pin P is no longer able to traverse the entire length of the slot. Px because it
brings the arm L against a stop L2 formed by the end of the slot in the side of the
box B through which the said lever I passes into the position shown in Figure 9
before it can itself reach either the upper or lower end of the slot P*. That is to
say, the crank pin P¹ can only describe a segment of the half circle, the versine of
which varies according to the position of the case M on the box B; consequently the
arm L is only moved to the left in the same proportion, and therefore the shutter is
only opened to a corresponding extent. Instead of the adjustment of the case M on
the lens mount being effected by the tangent screw W, as shown in Figures 9 and 10,
it may be adjusted by hand, and held in definite position by means of a spring
catch W taking into suitably placed notches on the edge of the flange M' of the
case M as shown in Figure 11.
In some cases it is required to open the shutter, and to hold it open a definite time
in order to obtain a longer exposure than can be obtained by the opening and
closing of the shutter by the unrestrained action of the crank pin operated by the
spring barrel, or while focussing. For this purpose we connect directly or indirectly
to the ratchet wheel by which the barrel is prevented from rotating, a dise or plate
having in its edge a single notch, or if preferred a projection; a releasing lever or
trigger is so arranged that a catch on the said lever or trigger is capable of engaging
with the teeth of the ratchet wheel, and another catch on the said lever or trigger
with the notch or projection on the edge of the disc or plate; but so that when the
one catch is engaged in the teeth of the ratchet wheel the other catch is held away
from and cannot engage with the notch or projection of the disc or plate, whilst when
the one catch is disengaged from the teeth of the ratchet wheel the other catch
bears against the edge of the disc or plate, and is free to engage with the notch or
projection thereon.

page_text: These arrangements are shown in Figures 12 to 15. O is a pawl held in gear with
the teeth of the ratchet wheel N by the spring O'. 02 is an arm extending from the
said pawl and terminating in a finger piece just outside the case M. Os is another
arm extending from the arm 02 and either shaped at its end to take into a notch on
the edge of the disc 0 secured on the ratchet wheel arbor N³ or, as shown in
Figures 12 and 13, shaped so as to fall into the path of a stop 0 on the said disc 0³.
O is a latch which prevents the arm 02 moving beyond à certain distance when
necessary as hereafter described. It will now be understood that if the latch 0° be
moved aside and the arm 02 be pressed by its projecting finger piece to the right in
Figure 13 so as to draw the pawl O out of gear with the ratchet wheel N³, the front
part of the arm ³ will be brought into the path of the stop 04, and the revolution
of the arbor N³ will be arrested when the said stop comes against the arm 03. The
portion of a revolution made however by the arbor N3 before it is stopped by the
arm 03 is sufficient to allow the crank pin P¹ to revolve far enough to open the
shutter to the extent defined by the adjustment of the case M on the box B, or of
the crank pin in the slot of its crank (Figures 3, and 5) as the case may be, and
as long as the arm 0 is held forward so as to prevent the stop 01 from passing, so
long will the shutter be held open. If however the arm 03 be moved back to the left
in Figure 13 far enough to release the stop O, but not far enough to place the pawl O
in gear with the ratchet wheel No, the arbor N³ will be free to continue its rotation,
and to allow the crank pin P¹ to complete its partial rotation and to close the
shutter. The exact position of the arm 02 to enable this to be done is defined by
the face 07 of the latch 0 if the latch 06 is closed back into the position shown
in Figure 15, or by the end of the moveable stop 08 which will have been moved
out into the path of the arm 02 by the latch 0 if the latter be left turned aside; so
that whether the arm 02 bears against the face 07 of the latch 0° or against the
stop thereof the arbor N³ is free to revolve. This latch 0° therefore serves also
as a means of defining the proper position of the arm 02, and consequently of the
pawl and arm or catch 03 when it is desired to allow the crank pin P to effect
the opening and closing of the shutter interruptedly.
In some cases it is sufficient, in order to obtain the necessary exposure, to retard
the action of the barrel and crank pin by means of a friction brake connected either
directly or indirectly with the spring barrel, somewhat as described in the specifi-
cation of a patent for which we applied on the 12th day of October 1887 No. 13,844.
In Figures 6, 7, 8 and 12, 13, 14 of the Drawings are illustrated two improved
arrangements of this brake apparatus suitable for the above described shutter-
actuating mechanism. In the arrangement shown in Figures 6, 7 and 8, R is a
kind of pincer the closed end of which is secured by the pin R', and the open end
of which embraces between its branches the ratchet wheel N or a disc mounted on
the same axis, leather washers 2 being preferably interposed between the branches
of the pincers and the said ratchet wheel or disc. R³ is a screw the head of which
extends to the outside of the case M, and has on it an index pointer R moving over
a graduated scale as shown in Figure 8 for indicating the amount of tension put on
the brake by the screw, and thereby inferentially, the speed at which the opening and
closing of the shutter will be effected. By tightening up or slackening this screw R³
more or less, by turning the index pointer frictional resistance is imparted to the
ratchet wheel N or to the disc, and the speed of revolution thereof and of the arbor N*
and crank P and consequently the speed of opening and closing the shutter is thereby
regulated to a certain extent."
In the arrangement shown in Figures 12, 13, 14 and 15 R is a brake strap,
preferably lined with leather, fixed to a pin R at one end, passing partly round a
brake drum R* on the axis N of the ratchet wheel N, and connected at the other
end to a screw Ra passing through the case M, and having an index pointer R*
working as a nut thereon. This index moves over a graduated scale as shown in
Figure 14 in the same way as the index R in Figure 5; and by turning the said
index the pressure of the brake strap R on the brake drum Rx may be varied so as to
increase or decrease the time of exposure within certain limits.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is :-
First Arranging the shutter-actuating mechanism so that it can be adjusted in
order to effect a greater or lesser opening of the shutter at pleasure, substantially as
herein before described.
Second Making the crank pin of the shutter-actuating apparatus adjustable
radially in its crank, for the purpose of varying the effect of said crank pin upon the
shutter. and thereby the extent of the opening of the said shutter substantially as
hereinbefore described, and illustrated in Figures 1, 3, 4, 5 and 6 of the Drawings
hereto annexed.
Third Making the shutter-actuating mechanism adjustable on the lens mount for
the purpose of varying the effect of the actuating crank pin upon the shutter and
thereby the extent of the opening of the said shutter, substantially as hereinbefore
described, and illustrated in Figures 9, 10 and 11 of the Drawings hereto annexed.
Fourth-The apparatus for holding the shutter open, consisting of the ratchet
wheel N and disc 05 provided with a notch, or a projection 04, the spring-actuated
axis N, the spring-actuated paw! O connected with the lever arms 03 and 0³, the
latch O and the stop 08, arranged, combined, and operating substantially as herein-
before described, and illustrated in Figures 12, 13, 14 and 15 of the Drawings
hereto annexed.
Fifth The combination of an index finger and graduated scale, with the regulating
screw of the friction brake device, for regulating the time of opening and closing
photographic lens shutters, substantially as hereinbefore described, and illustrated in
Figures 6, 8, 12, 13 and 14 of the Drawings hereto annexed.
Dated this 19th dox of October 1000