Improved Apparatus for Operating the Shutters of Photographic Cameras.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improved Apparatus for Operating the Shutters of Photographic
Cameras.
I, ROBERT EDWARD MATHER BAIN, of 417 Olive Street in the City of St. Louis,
and State of Missouri, United States of America, gentleman, do hereby declare
the nature of my said invention and in what manner the same
performed, to be particularly described and ascertained in and by the following
statement:-
is to be
My invention relates to improved means for operating the shutters of photographic
cameras, especially applicable to that class of shutters which swing past each other
within a casing surrounding the camera tube, each shutter having a circular opening
which coincides with that of the camera tube when the shutters are at half stroke.
Each shutter is formed with a curved slot through which passes the pivot pin of
the other shutter, and with a short straight slot. Through the last named combined
slots of the shutters and through vertical slots formed through the front and back
of the casing passes a pin, the whole operating so that on the full vertical movement
of the pin in either direction the shutters are opened and closed to the camera tube.
My invention has for its object to vary the speed of the shutters when opening and
closing the camera tube for instantaneous exposure, and consists in two (or more)
springs having different and alterable tension or force, and applied separately or
collectively, to the actuating pin of the shutters, whereby the speed of the latter when
opening and closing the camera tube for instantaneous exposure may be varied at
pleasure; combined with devices for holding and releasing the shutters and for
checking their movement when at half stroke or with the camera tube fully open.
On the accompanying drawings Figure i represents an interior view of the casing
surrounding a photographic camera tube and containing the shutters in their closed
positions; Figure 2 a front elevation of the casing and camera tube closed by the
shutters; Fig. 3 a left hand edge view thereof omitting the catches seen at the lower
part of figure 2; Figure 4 a rear elevation of figure 2 and Figure 5 a similar view
thereof, broken away, with the camera tube fully open, like letters of reference denoting
like parts in all the figures.

page_text: aa (seen more particularly in figure 1) represent the shutters having respectively
circular openings bb, pivots c c², curved slots d d' and straight slots e e¹ all being
arranged as shown within the casing surrounding the camera tube g so that by the
vertical movement in either direction of a pin i which passes through the combined
slots e el of the shutters a a¹ and through vertical slots in the front and back of the
casing the shutters a a¹ are swung past each other on their respective pivots c c²
and thereby open and close the camera tube g.
The pin in the present instance is fixed in and carried by a slide j which is mounted
between guides on the front of the casing f.
Bearing upwards against the pin i and normally closing the shutters a a¹ to the
camera tube g is the arm k of a spring which passes spirally round a fulcrum
stud 7 fixed to the casing f, and thence by an arm k¹ to a bar m which is fixed to the
casing and formed on its upper edge with a series of notches 1, 2, 3, 4, 5 (more or
less) in notch 1 of which the arm of the spring k k is shown locked.
Adjacent to, but shown out of contact with, the actuating pin i is the arin n of a
second spring n n which is of greater initial strength or tension than the spring k ki
and provided with fulcrum o and notched bar p, similar in all respects to the
spring k k¹.
By this arrangement (the pin i being previously pulled down against the pressure of
the spring by any suitable means in the ordinary operation of this class of
shutters a a¹) on releasing the pin i, the shutters a a¹ will be opened and closed in
instantaneous succession by the upward pressure of the spring kk on the pin i and at
a speed corresponding to the tension imparted to the spring kk when its arm k¹ is
locked in notch 1 of the bar m.
By successively shifting the arm k to the notches 2, 3, 4, 5 of the bar m the force
of the spring kk and speed of the shutters a a¹ will be correspondingly increased.
Or the arm of the spring k k¹ may be thrown out of contact with the actuating pin i
and the arm n of the spring n n¹ engaged therewith so that by shifting the arm n¹ to
to notches 2, 3, 4, 5 of the bar p further variations in the speed of the shutters a a¹
are obtained owing to the difference of strength between the said springs. Or again,
the arms kand n of the springs k k¹ and nn' may be engaged collectively with the
pin and the arms k¹n alternately or simultaneously shifted along the notches of
their respective bars m p for producing still further variations in the speed of the
shutters a a¹, this feature being of important advantage when taking instantaneous
negatives.
9 represents a lever catch pivoted to the back of the casing f, and formed with a
hooked end q¹ having a bevel shaped head which is normally held across the path of
the actuating pin by a spring q² connecting the lever 7 to the casing f, combined
with a stop pin q³ on the casing, so that the pin i, during its descent in the slots / for
making an instantaneous negative, forces back the catch q until clear of the hook q',
when the latter is returned by the spring q² and holds the pin i in the closed position
of the shutters a a¹ as seen in figure 4.
For releasing the hook q' from the pin i the lever q is thrown back on its pivot by
han or other suitable means.
In making a time exposure I use a stop lever pivoted to the casing f and formed
at its end adjacent to the actuating pin i with a tooth or catch which on the lever r
being thrown over to a certain extent on its pivot crosses the path of the pin i and
forms a stop thereto as seen in figure 5 when the shutters are at half stroke or the
camera tube g fully open.
The movement of the lever on its pivot may be restricted by the stop pin c which
projects through a slot ² in the lever r or by any other suitably arranged stop on
the casing f.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed 1 declare that what I
claim is :-
1. I
ennerain
1. 11

page_text: combination of two springs having different tensions, and means for altering the
respective tensions of said springs, with a pin passing through the shutters and
through slots in the shutter casing, substantially as and for the purpose herein before
described and illustrated by the accompanying drawings.
2: In apparatus for opening and closing photographic camera shutters, the
combination of two springs having different tensions, each of said springs passing
spirally round a fixed stud and engaging in either one of a series of notches formed
in a fixed bar, with the pin passing through the shutters and through vertical slots
in the shutter casing, substantially as and for the purpose hereinbefore described
and illustrated by the accompanying drawings.
3: In apparatus for holding and operating photographic camera shutters, the
combination of a spring kk lever q, pivoted to casing and having hooked end q¹
and spring q2 with stop pin 93, and pin i passing through slots in the casing and
through the shutters, substantially as and for the purpose hereinbefore described
and illustrated by the accompanying drawings.
4: In apparatus for holding photographic camera shutters, the combination of a
lever pivoted to casing and having a tooth or catch and slot engaged
by pin c with pin i passing through slots in the casing and through the shutters,
substantially as and for the purpose hereinbefore described and illustrated by the
accompanying drawings.
Dated this 11th day of January 1889.