Improvements in Photographic Shutters.
Year: 1890

page_text: Date of Application, 16th May, 1890
Complete Specification Left, 16th Feb., 1891-Accepted, 16th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Photographic Shutters.
I, JOHN RUDOLPH GOTZ, Optician, of 19, Buckingham Street, Strand, in the
City of Westminster, do hereby declare the nature of this invention to be as
follows:-
My invention relates to that class of shutters in which the passage for the light
is opened or closed by means of pivoted wings (usually four in number) distributed
symmetrically around the axis of the lens, each wing having a circular opening,
which in the open position of the shutter fits over the corresponding apertures of
the other wing.
The object of my improvements is, to render the clear opening variable in size,
and to provide better means for regulating the time of exposure.
As usual in this class of shutters, one of the wings is turned on its pivot by means
of a coiled spring, and the other wings are connected with the first, or leading wing,
by means of pins and slots, so as to follow its motion.
On the axle of the spring barrel, or on the face of the latter, is mounted a crank
provided with a crank pin which during the revolution of the crank comes in
contact with a lever mounted on the axle of the leading wing and thereby turns the
latter on its axis more or less, according to the time during which the crank pin
remains in contact with the said lever. This time is regulated by turning the lever
on its axis (within certain limits) independently of the wing, for which purpose the
said lever is loose on its axle and provided with a toothed segment gearing into an
endless screw, which is held in a bearing fixed to the face of the leading wing.
This regulating screw has a milled head and an index finger, which shows on a
graduated scale the aperture of the shutter which corresponds to that position of
the lever. For turning the wing back into its closing position, a second lever or
curved horn is fixed on the axle of the wing in such a position, that it is turned by
the same crank pin at the required time of its revolution.
In order that the clear aperture of the shutter may be nearly circular, whether
the aperture is large or small, the aperture of each wing is circular, with the
exception of the side, on which the wings cross each other which is a parabolic or
hyperbolic curve forming a tangent to the circle.
The shutter is operated as usual by means of an air bag and a flexible pipe con-
taining a valve, which controls the position of a disengaging lever serving to retain
the spring barrel or a disc fixed on the axle of the spring, so as to prevent the
spring from uncoiling before the required time.
The said valve closes the inlet of an air cylinder, which serves to regulate the
speed of the shutter, in the following manner :-
The air cylinder has two or more slots or perforations and contains a hollow
piston, the rod of which is provided with a concave head intended to meet the crank
pin mentioned above during its revolution.
By compressing the air bag, the valve is lifted from its seat, compressed air
enters the cylinder and drives the piston forward, so as to place the concave
head of the piston rod within reach of the crank pin. After the latter has
opened the shutter, which occurs during the first half of its revolution, it
continues to turn and meets the head of the piston rod, thereby pushing the
piston back into its original position. This motion of the crank pin is retarded
by the resistance of the air enclosed in the cylinder, and can be made quicker
or slower, according to the size of the perforations or air outlets formed in the
walls of the cylinder. These outlets may be covered more or less by means of
a slide which can be moved by a rack and pinion. The position of the pinion,

page_text: and thereby the speed of the shutter, is indicated by means of a pointer fixed
on the axle of the pinion, and a graduated arc fixed on the base-plate or frame
of the shutter.
As mentioned above, the spring or spring barrel is retained in its position by
means of a two-armed disengaging lever, one extremity of which rests on a pin
projecting from the side of the air valve and guided in a slot of the valve casing
The opposite extremity of the disengaging lever is pressed by a spring against a
flat segment of a circular cam or disc projecting from the face of the spring barrel
and concentric with the same. Near the said segment the spring barrel has a
detent, or pin adapted to come in contact with a corresponding hook or catch at the
extremity of the disengaging lever, during each revolution of the barrel.
If the air valve is lifted, it raises the near extremity of the disengaging lever,
thereby disengaging the opposite end of the said lever from the spring barrel and
cam mentioned above, and allowing the spring barrel to turn on its axis, until, after
an entire revolution, the hook of the lever falls in behind the detent or tooth of the
spring barrel, and prevents the further motion of the same.
In order to stop the spring barrel, after it has made half a revolution, I employ
a second disengaging lever parallel to the first and a second segmental cam and
detent, which can be brought into action, when desired, by turning the second
disengaging lever slightly on its axis, and then fixing it to the first disengaging
lever. For this purpose, one end of the second disengaging lever carries a pin
which projects into a curved slot of the first lever. If the second disengaging
lever is turned out of the reach of the detent, the first lever acts alone; otherwise
the two levers act alternately.
Dated this 15th day of May 1890.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Photographic Shutters.
I, JOHN RUDOLPH GOTZ, Optician, of 19 Buckingham Street, Strand, in the City
of Westminster, 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 that class of shutters in which the passage for the light
is opened or closed by means of pivoted wings, (usually four in number) distributed
symmetrically around the axis of the lens, each wing having a circular opening,
which in the open position of the shutter fits over the corresponding apertures of
the other wing.
The object of my improvements is, to render the clear opening variable in size,
and to provide better means for regulating the time of exposure.
As usual in this class of shutters, one of the wings is turned on its pivot by means
of a coiled spring, and the other wings are connected with the first, or leading
wing, by means of pins and slots, so as to follow its motion.
In the following description reference will be made to the accompanying
drawings, Figs. 1 to 12, of which
Fig. 1 is a front elevation of a shutter, after removal of the cover or face plate,
so as to show the interior, the shutter being fully open.
Fig. 2 is a back elevation of the same in its open position after it has been
adjusted to the smallest aperture.
Figs. 3 and 4 are horizontal sections through the upper part of the shutter taken
on different planes.
Figs. 5, 6 and 7 are partial vertical sections.
Figs. 8 to 12 show certain details, as will be hereafter described.

page_text: On the axle of the spring barrel, or on the face of the latter, is mounted a
crank B provided with a crank pin b, which during the revolution of the crank
comes in contact with a lever Cmounted on the axle c of the leading wing
and thereby turns the latter on its axis more or less, according to the time
during which the crank pin remains in contact with the said lever. This time
is regulated by turning the lever on its axis (within certain limits) independently
of the wing, for which purpose the said lever is loose on its axle and provided
with a toothed segment gearing into an endless screw D, which is held in a
bearing d fixed to the face of the leading wing. This regulating screw D has
a milled head and an index finger d, which shows on a graduated scale the
aperture of the shutter corresponding to that position of the lever.
For turning
the wing back into its closing position, a second lever or curved horn E is
fixed on the axle of the wing in such a position, that it is turned by the same
crank pin at the required time of its revolution.
In order that the clear aperture of the shutter may be nearly circular,
whether the aperture is large or small, the aperture of each wing is circular,
with the exception of the side on which the wings cross each other, which is a
parabolic or hyperbolic curve (a', a² a³, a³,) forming a tangent to the circle.
When the four parabolic curves are joined together as in Fig. 2, the clear
opening is almost a complete circle. Figs. 11 and 12 show two of the wings
coupled together by a pin a passing through a slot.
The shutter is operated as usual by means of an air bag (not shown in the
drawing) and a flexible pipe G communicating with a valve, F, which controls the
position of a disengaging lever H serving to retain the spring barrel, or a disc fixed
on the axle of the spring so as to prevent the spring from uncoiling before the
required time.
The said valve F closes the inlet i of an air cylinder I (Figs. 1, 3 and 6) which
serves to regulate the speed of the shutter, in the following manner :-
The air cylinder I has two or more slots or perforations Fig. 4, and contains a
hollow piston J, the rod j of which is provided with a concave head (Fig. 1) intended
to meet the crank pin mentioned above during its revolution.
By compressing the air bag, the valve is lifted from its seat, compressed
air enters the cylinder I and drives the piston J forward, so as to place the
concave head of the piston rod j within reach of the crank pin (Fig. 1). After
the latter has opened the shutter, which occurs during the first half of its
revolution, it continues to turn and meets the head of the piston rod, thereby
pushing the piston back into its original position. This motion of the crank pin
is retarded by the resistance of the air enclosed in the cylinder I, and can be
made quicker or slower, according to the size and number of the perforations
or air outlets formed in the walls of the cylinder. These outlets may be
covered more or less by means of a slide K which can be moved by a rack
and pinion L, Figs. 1 and 4. The position of the pinion, and thereby the speed
of the shutter, is indicated by means of a pointer 1 (Fig. 2) fixed on the axle
of the pinion, and a graduated arc fixed on the base plate or frame of the
shutter.
Instead of retarding and regulating the motion of the crank by means of an air
cushion enclosed in a cylinder, I may employ à coiled spring, as indicated in Fig. 3
by dotted lines.
As mentioned above, the spring or spring barrel is retained in its position by
means of a two-armed disengaging lever, H, one extremity of which rests on a pin f
projecting from the side of the air valve F and guided in a slot of the valve casing,
Fig. 6. The opposite extremity of the disengaging lever H is pressed by a spring M
against a flat segment of a circular cam or disc N, Fig. 10, projecting from the
face of the spring barrel and concentric with the same. Near the said segment
the spring barrel P has a detent p, Figs. 3 and 10, or pin adapted to come in
contact with a corresponding hook or catch h at the extremity of the disengaging
lever, during each revolution of the barrel.

page_text: If the air valve is lifted, is raises the near extremity of the disengaging lever, H,
thereby disengaging the opposite end of the said lever from the spring barrel P and
cam mentioned above, and allowing the spring barrel to turn on its axis, until, after
an entire revolution, the hook of the lever H falls in behind the detent or tooth of
the spring barrel, and prevents the further motion of the same.
In order to stop the spring barrel after it has made half a revolution, I employ a
second disengaging lever R parallel to the first and a second segmental cam Q and
detent n which can be brought into action when desired, by turning the second
disengaging lever B slightly on its axis r, and then fixing it to the first disengaging
lever H. For this purpose, one end of the second disengaging lever carries a
pin which projects into a curved slot of the first lever. If the second dis-
engaging lever is turned out of the reach of the detent, the first lever acts alone;
otherwise the two levers act alternately.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is:
1. In photographic wing-shutters, the method of or means for varying the travel of
the leading wing, and consequently the clear opening of the shutter, substantially as
described.
2. In photographic wing-shutters, the shape of the central opening of each wing,
in order to render the clear aperture nearly circular, when the shutter is adjusted
for less than its maximum aperture, substantially as described.
3. In photographic shutters, the means for varying the speed of the crank, and
consequently the time of exposure, substantially as described.
4. In photographic shutters, the means for stopping the main spring, and thereby
arresting the shutter, after the same has performed half its usual travel, substantially
as described.
5. An adjustable photographic wing-shutter, constructed and adapted to operate
substantially as described.
Dated this 16th day of February 1891.