Improvements in Instantaneous Shutters for Photographio Apparatus and the like.
Year: 1888

page_text: Date of Application, 12th Dec., 1888
Complete Specification Left, 12th Sept., 1889-Accepted, 2nd Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in Instantaneous Shutters for Photographio
Apparatus and the like.
We EMILE TOURTIN, photographer, and LODOÏSE PARSY, gentleman, both of
8 Boulevard des Italiens, Paris, France, do hereby declare the nature of this invention
to be as follows:-
:-
Our invention is based on the observation of the following principle the application
of which by us is, we believe, entirely novel:
If an opaque screen of any given shape is placed in sufficient proximity to a
photographic lense, either in front of, at the back of, or between the system of lenses,
like a diaphragm, the formation of images at the focal plane is not altered in any
way; the sharpness remains as perfect the luminous intensity only being reduced in
the same ratio than that of the surface of the opaque screen to that of the lens.
If the screen so interposed in the direction of the luminous rays be in the shape
of a grating that is to say with alternating plain and hollow parts the above
mentioned fact will occur. In effect, the light rays emanating from an object
situate at any distance greater than the focal length of the lens are in no way checked
by the interposition of the grating and are refracted in exactly the same manner as if
there was no obstruction, the light rays striking against the plain parts of the
grating are, it is true, lost but the image remains quite as sharp although it is less
brillant.
If another identical grating is placed in front of the former one, the plain parts of
one corresponding to the hollow parts of the other, and is made to slide against it, it
will, at both the beginning and the end of the journey, act as an obtuvator and,
meanwhile the openings of the fixed gratings will have been gradually opened and
shut again the greatest amount of light being admitted when the openings of the two
gratings exactly correspond with each other."
If this apparatus is adapted to a lens placed in front of a camera and is operated,
the usual luminous impression will be obtained at the focal plane with this advantage
that as the displacement of the moveable grating may be made as short as desired by
multiplying the number of bars, the duration of exposure is proportionately reduced
and can be made to correspond to almost absolute instantaneousness.
But such a shutter absorbing a great proportion of the light (a minimum of one
half in the theoritical supposition of the bars and the hollows being of equal widths),
could only be used for photographic purposes in the case of an exceptionally intense
light being available. The same reasoning applies to a shutter with bars and hollows
radiating from a centre but the latter offers this disadvantage that the central rays of
light which are the more important would be intercepted.
The arrangements described would prove very suitable for photographic purposes
if the substances used were of a sufficient degree of sensitiveness; but with the
materials actually to be obtained in the market, we construct our shutter with a series
of parallel blades similar to those of a venitian blind and which are acted upon by.
means of an appropriate mechanism; they turn together of a same angular motion
and without loosing their parallelism.
Each blade is mounted on two pivots, one at each end, lodged in the casing of the
camera, and also provided with a pinion. All these pinions are in gear with a
toothed rack the forward and backward motion of which causes all the blades to
simultaneously turn in one direction or in the other. The motion of the blades could
equally be obtained by means of mechanical arrangements of any other description
such as pullies and tape or string, articulated levers, etc.

page_text: If the rack or rod is pushed home in one direction, the blades are all closed and a
spring catch maintains the shutter so constituted closed until it is released by means
of the ordinary pneumatic india rubber ball or any other contrivance; at that
moment, the rack or rod is shot to the other extreme position by means of a spring
provided for the purpose. In the interval the shutter has been opened and shut
again.
The tension of the spring and the consequent degree of instantaneousness which it
is desired to obtain may be regulated at will by means of a thumb screw and is
indicated on a dial by a pointer following the motion of the regulating thumb
screw.
The angular motion of the blades is about 180 degrees; they overlap each other so
as to constitute a perfect obturator and their number may vary from one single one to
any number.
When the shutter is arranged to act in a vertical direction, the spring may be
dispensed with if the weight of the rack or rod is sufficient to insure the working of
the system; the action of gravitation may even be retarded, if found too quick, by
means of a brake or friction piece, dash pot, etc.
The shutter may be fixed in front or at the back of the lens, or even between the
system of lenses; it is set in the centre of the apparatus by means of three set
screws.
It will readily be understood that in our system of shutter the quickness obtained
is greater than with the guillotine, either single or double, horizontal or vertical.
In the latter case, in effect, the light acts, at the same moment, upon the totality
of the sensitized plate; small at first, it gradually increases to gradually decrease
again and the motion of the object to be photographed affects the plate from the
beginning to the end of the exposure.
With our shutter, the plate is only gradually affected, the luminous beam travelling
in a direction opposite to that of the blades; the said beam is wider or narrower
according to the distance between the blades and the width of the said. Consequently
should the width of the beam be equal to one half of the height of the sensitized
plato, the same quickness than that obtained with a guillotine shutter will be obtained
with our blade shutter in half the time.
Another advantage of our system is that its speed remains constant whatever the
size of the lens as the blades always travel the same distance.
As to the amount of light intercepted by the blades, it is almost insignificant not
exceeding the proportion of about 1 in 30.
Our shutter is applicable to other apparatus such as magic lanterns, projection and
other apparatuses intended for the instantaneous sending or receiving of beams or
flashes of light.
London Twelfth Danamho 1000
J. A. BERLY,
Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Instantaneous Shutters for. Photographic
Apparatus and the like.
We EMILE TOURTIN, photographer, and LODOÏSE PARSY, gentleman, both of
8 Boulevard des Italiens, Paris, France, 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:—
Our invention is based on the observation of the following principle, the method of
application of which by us is, we believe, entirely novel :
If an opaque screen of any given shape is placed in sufficient proximity to a
photographic lens, either in front of, or at the back of, or between the system of
lenses, like a diaphragm, the formation of images at the focal plane is not altered in

page_text: any way the sharpness remains as perfect the luminous intensity only being reduced
in the same ratio than that of the surface of the opaque screen to that of the lens.
Our improved instantaneous shutter is composed of a series of parallel blades
similar to those of a venitian blind and which are acted upon by means of a suitable
mechanism; they turn together of a same angular motion and without loosing their
parallelism.
Fig. 3 is a profile and
Fig. 4 is also a profile of our improved instantaneous shutter.
Each blade c is mounted on two pivots, one at each end, lodged in the casing of
the shutter and also provided with a pinion d at one end.
These pinions are all in gear with a toothed rack e the forward and backward
motion of which causes all the blades to simultaneously turn in one. or the other
direction.
This motion of the blades could equally well be produced by any other mechanical
contrivance such as pullies or pinions worked with string, tape, or chain, or by means
of articulated levers, etc.
In Fig. 4 the rack e is shown in one of its two positions, that one ready for
operating the blades are all shut and a spring catch pressing against the rack e
maintains the shutter so constituted closed until the rack is released which is done by
relieving the pressure of the spring catch by means of an ordinary pneumatic india
rubber ball or of any other contrivance. At that moment the rack is shot to its
other extreme position through the action of the spring 9 provided for the purpose;
in the interval the shutter has been opened and closed again.
The tension of the spring g and the consequent degree of quickness which it is
desired to obtain can be regulated at will by means of the thumb screw h which runs
into a slot and it is indicated on a graduated scale by the pointer k which follows
the motion of the thumb screw h.
The angular motion of the blades is about 180 degrees; they overlap one another
so as to constitute a perfect obturator and their number may vary from one single
one to any number.
When the shutter is arranged to act in a vertical direction, the spring 9 may be
dispensed with if the weight of the rack or rod e is sufficient to insure the effective
working of the system; the action of gravitation may even be retarded, if found too
quick, by means of a brake or friction piece, dash pot, etc.
The shutter may be fixed at the front or at the back of the lens, or even between
the system of lenses; it is set in the centre of the apparatus by means of three set.
screws m. m. m.
It will readily be understood that with our system of shutter the degree of quickness
obtained is greater than with the guillotine, either single or double, horizontal or
vertical.
In the latter case, in effect, the light acts, at the same moment, upon the totality of
the sensitized plate; small at first, it gradually increases to gradually decrease again
and the motion of the object to be photographed affects the plate from the beginning
to the end of the exposure.
With our shutter the plate is only gradually affected, the luminous beams travelling
in a direction opposite to that of the blades; the said beam is wider or narrower
according to the distance between the blades and the width of the said. Consequently,
should the width of the beam of light be equal to one half of the height of the
sensitized plate, the same quickness than that obtained with a guillotine shutter will-
be obtained with our blade shutter in half the time.
Another advantage of our system is that its speed or quickness remains the same,
whatever the size of the lens as the blades always travel the same distance.
As to the amount of light obstructed by the blades it is almost insignificant not
exceeding the proportion of 1 in 30.

page_text: Our shutter is applicable to other apparatus such as magic lanterns, projection,
signalling or other apparatuses intended for the instantaneous transmission or reception
of flashes of light.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :
The construction of an obturator or instantaneous shutter, for photographic or
other purposes and made of a series of revolving blades substantially as set forth and
illustrated.
Paris, Eleventh September 1889.
J. A. BERLY,
Agent for the Applicants.