An Improved Photographic Camera Shutter.
Year: 1898

page_text: Date of Application, 28th Apr., 1898-Accepted, 27th Aug., 1898
COMPLETE SPECIFICATION.
An Improved Photographic Camera Shutter.
We, FRANCIS LIDDELL and GEORGE ROBERT CANDELET, both of 157, Whitfield
Street, in the County of London, Manufacturers, 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 present application for Letters Patent relates to an improved shutter for a
photographic camera, adapted for use either as an instantaneous shutter, or for
time exposures.
The shutters of this description hitherto in use possess various drawbacks,
inasmuch as they are complicated and consequently expensive to construct, and
require more space for their operation than can conveniently be provided in a
small hand camera. Moreover in the cameras at present in use the actuation
of the device is usually effected by aid of a long stroke of the outside lever or
equivalent device.
I have overcome these drawbacks, and constructed a rapid, accurate, and reliable
instrument composed of a minimum number of separate parts, completely under
control of the operator, and admitting of very various exposures.
In order to make my invention clear I will now proceed to describe the same
with reference to the accompanying drawing in which
Figure 1 is a view of the front of the camera with the shutter visible and in
the position of rest, the outer covering plate having been removed.
Figure 2 shews the apparatus in position for a time exposure, and also during
the instant of instantaneous exposure (the bolt being pushed aside).
Figure 3 shews the apparatus in the extreme position just before the release
of the shutter.
The operative parts of the device are arranged as follows:-
The outer plate A preferably of the form shewn in the drawing, is provided
with the quadrangular aperture a and revolves upon the central pivot a A
coiled spring 6 is attached at one end to the outer plate A as shewn in the draw-
ing, its other end being fixed to the adjustable lever c, revolving on the pivot d
At the opposite side of the shutter to the point of attachment of the spring bis
placed the projecting leaf spring E. This spring is integral with the shutter
aforesaid, and is preferably of the construction shewn in the drawing, having its
point of connection with the shutter somewhat weakened by the cut-out pieces
as shewn in the drawing. The action of the said spring will be explained further
on.
The lower shutter B is more or less similar in shape to that commonly employed
in instantaneous shutters. It possesses an aperture i corresponding in size to
the aperture o in the wall of the camera. This aperture o is shown slightly
smaller than the aperture in the drawing for the sake of clearness. The
plate B consists essentially of a segment of a circle also revolving on the pivot e
within the limits of its motion. The plate B is flat, with the exception of its
lowermost right hand edge which terminates in a ridge g, so arranged as to be

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radial with regard to the central pivot e, and to stand at right angles to the plane
of the said piece B. The upper shutter A can be restricted in its movement by
the interposition of the pin or stop j (Fig. 2) which may be actuated in any
convenient manner. In the drawing it is shewn as controlled from the outside
by means of the axle and lever handle m; the position of the said handle serves
moreover as an indicator to the user to shew whether the shutter is working as a
time" or an "instantaneous mechanism. Below the piece B there is placed
the two-armed check lever D. This lever revolves upon the pivot n and is pivot-
ally connected to the push bar q, which bar stands under the control of the spiral
spring secured at its other end to the link s revolving on the pivot t.
This
piece D forms a controlling and actuating device for the lower shutter B inasmuch
as the upturned flange g of the said piece is permanently situated between the
arms of the said piece D.
As will be seen from the drawing, these arms are so constructed as to remain
constantly in contact with the said flange g, and to actuate the same principally
by the sliding contact of two surfaces at the same moment, never releasing the
said flange entirely from the control of one or the other arm of the lever, whilst
in the terminal positions the flange g abuts against the flat outer end of one or
the other arm of the lever D. The stud is provided at a suitable point to lift
the outer shutter A from out of contact with the lower shutter B with which it
normally engages by aid of a little projection & on B, and thereby to enable the
said shutter A to spring back under the influence of the spring b.
The device operates as follows:
The several parts being put in place and suitably adjusted the apparatus will
assume the position shewn in Figure 1 in which both the spring b and the spring r
are in the position of rest. If the bar q be forced inwards by the pressure of the
finger, and the spring consequently stretched, the lever D will be pushed over
into the position shewn in Figure 3, causing the shutter B likewise to revolve
around its central pivot e into the position shewn in Figure 3, and carrying with
it the outer shutter A through the engagement of the catch in the spring E
in opposition to the spring 6 which is consequently stretched.
When the two
shutters thus united arrive at the position shewn in Figure 3 the spring E strikes
upon the fixed stud v, and when the spring E impinges upon this stud it is lifted
up thereby, and the catch a is released. This causes the shutter A to fly back
into its original position under the tension of the spring b, passing in its course
in front of the aperture o with which the aperture coincides in the then position
of the piece B, and thus affords an instantaneous exposure.
The exact period of time during which this exposure lasts is determined by the
force of the spring b, and this may be regulated by adjusting the tension of the
spring by means of the double armed lever e pivoted on d. In the drawing
three positions are provided for the said lever marked respectively 1, 2, 3, a small
hole at each of these points affording a sufficient support to retain a projection
on the underside of the adjusting arm of the lever in place.
When it is desired to use the camera for a time exposure, the retaining bolt j
is caused to intercept the outer plate A and to hold the same permanently in
the position shewn in Figure 2 in which the aperture a corresponds with the
aperture o. Also the plate B is prevented from passing beyond the bolt ; on its
backward movement. In this case the plate B alone moves, and when the bar
is pushed in by the finger of the operator the plate B rotates until its aperture i
corresponds in position with o, and thus the time exposure is obtained, which is
prolonged until the bar q is released, and the plate b springs back under the
influence of the spring r.
q
In constructing my shutter I may make the moving parts of the mechanism of
thin sheet metal or other suitable material, and they are preferably cut or stamped
out of single pieces of thin sheet steel or aluminium bronze or other material of
combined strength, elasticity and lightness.
It will be obvious that the various pieces may be arranged in different positions

page_text: with regard to one another to some extent without departing from the principle
of my invention.
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 a spring shutter mechanism for a photographic camera, the metallic
outer plate A having the leaf spring E integral and of identical material there-
with, substantially as and for the purpose described.
2. In a spring shutter mechanism for a photographic camera, the two-armed
lever I constructed and operating substantially as described in the accompanying
drawing.
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3. The combination of parts forming the improved spring shutter mechanism
for time or instantaneous exposures," substantially as described and shewn
in the accompanying drawings.
Dated the form ay
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicants.