Year: 1888

page_text: Date of Application, 30th Aug., 1888
Complete Specification Left, 19th Jan., 1889
Complete Specification Accepted, 23rd Feb., 1889
RESERVE CC
I, LOUIS HOUSSARD 5, Wilmington Square Clerkenwell W.C., Photographic
Instrument Maker do hereby declare the nature of this invention to be as follows:-
An improved shutter for Photographic Camera being an improvement in quickness
and regulation of speed of exposure; also, being shakless in action. The shutter is
composed of a thin Brass box of rectilinear form, an aperture being in the centre.
Inside of the box are two sliding plates which open from centre of the aperture in
opposite directions. The aperture of the sliding plate can be made to open round,
oval, or square.
At the bottom to the left of the box is a small divided wheel for
regulating the speed of exposure. On the right hand side of the box is fitted
Pneumatic and hand release, also a focussing lever, the shutter can be fitted on hood
or between lens.

page_text: I, LOUIS HOUSSARD 5 Wilmington Square, Clerkenwell, W.C., Photographic Instru-
ment Maker, 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 Photographic shutters which are opened and closed
automatically, and has for its object to produce a shutter, the rapidity of the closing
and opening of which shall be under the control of the operator, so that the exposure
may be varied at will from the instantaneous, to any lengthened interval, such length
of exposure being determined by the employment of a friction damper, and focussing
lever hereinafter to be more fully described, at the same time the shutters shall be
actuated without shaking or otherwise disturbing the Camera.
In order that my invention may be the better understood I have appended the
accompanying sheet of drawings in which Figures 1 and 2 are respectively front and
side elevational views of the improved shutter according to my invention. Figure 3
is an internal elevational view of the cover of the containing case showing the parts of
the mechanism attached thereto; Figure 4 is a similar view of the enclosing case,
Figure 5 is a detached view of the friction damper. Figure 6 is a detached view of
the releasing levers and Figure 7 is a sectional view of the spring box and spring
for actuating the shutter mechanism.
:
a is.
The device or appliance according to my invention comprises an enclosing case A
provided with a cover a which is secured to said enclosing case A. by screws or
equivalent means...The enclosing case A and cover a are provided with aperturos
through which the rays of light pass. Within the enclosing case are two sliding
plates B. C. free to move vertically within suitable guides b. c. and are provided with
round, elliptic, square or other shaped apertures to allow of the rays of light,
when said apertures are coincident with the apertures in the enclosing case A
and cover a, to pass therethrough. At the upper part of the cover
supported in suitable bearings a narrow plate D Figure 3 pivoted in the centre and
slotted at each end, into which slots take the pins d, d, fixed to opposite corners in
the upper parts of the sliding plates B, C. Upon the lower part of the plate C, is
secured a thin plate e baving formed therein a horizontal slot into which takes a pin f
secured to a cam E Figures 3 and 5, whereby the sliding plates Bare moved
simultaneously in opposite directions. Beneath the aperture in the cover a are
disposed two releasing levers F. G, which may be caused to act conjointly with, or
independently of each other according to the required degree of exposure, a suitable
handle H and pin serving to secure said two releasing levers together. The
releasing levers F. G, which are retained in the normal position by a spring g, are

page_text: actuated by means of a pneumatic air tight piston I which, upon air being forced
thereinto, shoots out a pin i against a small projection formed upon the lever F
which latter it raises, thus releasing the mechanism. To the cam E is adapted a
spiral spring J Figure 7 enclosed in a small box K secured to the exterior of the
cover a of the enclosing case, the free end of the spring taking into a small perfora-
tion form in the milled cap k which latter is secured to the cam E by a screw / or
equivalent means. Now, in actuating the apparatus built up in the manner above
described, the cap is turned half a revolution against the tension of the spring J,
when the pin fin the cam E is caught and held by the curved arms L of the releasing
levers F. G. In this act of winding the spring J, the cam E performs a semi-
revolution the pin therein in its travel, raising the plate a distance determined by
the distance of said pin ƒ from the axis of the cam E. When the pin is in a plane
horizontal to the axis of the cam, the sliding plate will be in its lowest position, and
when it reaches a point vertical with the axis of the cam, said sliding plate will be
at its highest point, and the apertures in the enclosing case A and cover a will be
Ancovered. On the cam E containing its semi-revolution; the pin f therein carries
the sliding plate down again to its normal position. It follows therefore that,
inasmuch as the two plates are connected together by means of the pins and
slotted arm D the motion imparted to the sliding plate C is transmitted to the sliding
plate B, giving to the latter a movement in a direction opposite to that of the sliding
plate C, by which means each semi-revolution of the cam causes the apertures in
the two plates B. C. to be brought coincident with each other for such length of time
as may be desired, irregularity in the movements of said plates, through the variation
in the tension of the spring J, being compensated for by a light spring p bearing
against a pin secured to the slotted plate D.
The speed of the motion of the sliding plates, and consequent duration of the
exposure of the sensitive plate in the Camera, is governed and regulated by means of a
damper M Figure 4 of any suitable material, such for instance as cork mounted upon
a fine spring secured within the case A, which damper is caused to approach and
press against a disc m rigidly secured to the cam E by a screw and thumb nut N
Figure 1, the degree of pressure of the damper upon the disc m being denoted by
means of an index pointer and graduated scale », or, if desired, the thumb nut N
may have graduated marks formed thereon.
In order to allow of the focussing of the lenses of the Camera, I provide a focussing
lever Figures 1 and 2 pivoted to that side of the enclosing case A from which
extend the levers F. G in such a manner as to press against the lever G when released
by the blow of the pin i, thus, having turned the cap K and cam E against the tension
of the spring J, to set the mechanism, the handle of the focussing lever O is pressed
forward, and when the levers F, G, are forced upwards by the pin i, said levers are
held by the focussing lever O aforesaid, keeping the apertures in the sliding
plates B. C. coincident. When the focussing has been properly effected the
levers F, G, are released by drawing back the bandle of the focussing lever O,
when the apparatus will be ready for use.
From the foregoing it will be seen that there being no complicated mechanism,
the simplicity of the various parts renders it little liable to become deranged,
at the same time, by virtue of the freedom and smoothness with which the mechanism
works, all vibratory disturbance is prevented.
The improved Photographic shutter above described may be adapted to the hood of
a camera or placed between the lenses as may be desired.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
First The improved Photographic shutter whereby the interval of exposure of a
sensitised plate may be varied according to circumstances substantially as herein
described and illustrated in the accompanying drawings.

page_text: Second-In the Photographic shutter herein described and referred to in the pre-
ceding claim the adaptation thereto of a suspended slotted plate D whereby in combina-
tion with the pins d' on the sliding plates B. C. and pin f on the cam E said sliding
plates B. C. are caused to move in opposite directions against the tension of a spring
substantially as and for the purpose herein set forth and shown.
Third: In a Photographic shutter the employment of a spring to compensate for
the varying tension of the spiral spring J substantially as herein set forth.
Fourth-In a Photographic shutter the adaptation thereto and employment there-
with of a friction damper M. bearing against the surface of a disc m substantially as
and for the purpose herein described.
JAMES STEVENSON,
Gray's Inn Chambers,
20, High Holborn, London, W.C.,
Agent for Applicant.