Improvements in Photographic Apparatus..
Year: 1893

page_text: Date of Application, 19th Dec., 1893-Accepted, 24th Feb., 184
COMPLETE SPECIFICATION.
Improvements in Photographic Apparatus..
I, GEORGE DEMENY, Scientist, of Levallois-Perret, near Paris, in the Republic
of 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 :-
This invention for improvements in photographic apparatus has for its object to
onable a series of photographic images to be taken at equal and very short intervals
on a sensitized film and consists essentially of an opaque disc adapted to be rotated
and provided with an opening and of a sensitized band cut off from the light except
when the disc opening is opposite the band and geared to the disc in such manner
that it is stationary whilst the disc opening is passing it and is then moved onwards
so that a fresh part of the band is opposite the disc opening when next it comes
opposite the band.
In the accompanying sheet of illustrative drawings ;—
2
Fig. 1 is a back elevation with the back cover supposed removed of a complete
photographic camera constructed according to this invention and
Fig. 2 is a vertical section on M N, and
Fig. 3 is a horizontal section on 1' Q of the saine.
Fig. 4 is a side elevation of the camera to a reduced scale.
Figs. 5 to 8 are detail views of the intermittent motion for the sensitized band.
The apparatus comprises a flat box divided into two compartments A A'. In
the first compartment A is the disc shutter B passing close to the sensitized
plate C. In the second compartment A' is arranged the mechanism which operates
the movement of the sensitized plate. The box is provided with any suitable lens
and it may be fixed on a movable stand or pivots so that it may be easily adjusted
in any direction or made to follow an object in movement.
In order to effect the intermittent motion of the sensitized band or film C it is
rolled ou a bobbin D and protected from the action of light by a band of opaque
paper which serves for its extension. The paper may be replaced by the support
of the sensitized film itself rendered opaque by any suitable method: The bobbin D
is forced on to a pin E and turns with it. A plate a is also fixed on the pin D and
a spring ↳ hears upon it so as to prevent the momentum of the bobbin D from
From the
carrying it forward when the movement of the band film ceases.
bobbin D the film C passes over two rollers cc on which it is stretched and between
which the sensitized surface receives the impression of the light. The rollers c
allow of the movement of the film with the least possible friction. From the
rollers c the film passes to and is wound on a second bobbin D' to which its end is
attached at the commencement of the operation.
The bobbin D' which takes the film after it has received the exposure instead
of being coaxial with the shaft d on which it turns is fixed on a pin E extending
eccentrically from this shaft, so that when the shaft d is turned with regularity
the film winds round the bobbin D' with a variable speed which becomes nil at a
certain point. It is exactly at this moment of stoppage of the film tliat the
opening of the shutter disc B comes opposite and passes the film.
The axis O of the disc B and the axis d which carries the eccentric bobbin D'
are connected together by bevel gearing and are thus in positive connection.
The duration of the exposure of the film C is known mathematically and the
movement of the film is positive whilst a tension indispensable to the clearness of
the image is assured.
Different shapes and different eccentricity could be given to the boblin D' on
which is wound the film which would also permit of instantaneous exposures of fle

page_text: film being obtained under the conditions just explained. Thus with the oval shape
shown in Fig. 5 the exposure of the film will take place during a larger fraction of
the duration of rotation than with a cylindrical bobbin.
Instead of a bobbin a plate D' as shown in Fig. 6 can be used which will also
give a longer duration of exposure. A double plate D³ as shown in Fig. 7 can
also be used and this will give two stoppages for each complete revolution; this
arrangement can be combined with two openings opposite one another on the
shutter disc so that two negatives would be obtained at each turn of the disc.
All these combinations in which the winding of the film takes place with a
variable speed give known exposures which can be made to coincide with the
passage of one or several openings on the disc.
The eccentric motion can be introduced into the path of the film which is
wound as shown in Fig. 8 on a bobbin D¹ turning at a uniform speed actuated by
the shutter disc.
The film passes from the bobbin D over the rollers e past the opening over the
eccentric D to the bobbin D¹. The eccentric D₁ turns about an axis connected
by gearing to the bobbin D' and thus to the axis of the shutter disc.
The effect of this eccentric D is as follows:-The bobbin D' actuated by the
disc moves the film in a uniform manner, but the eccentric D* on which the film
bears increases the length of the path c D'D' so that the speed of unwinding is
increased and then diminishes the path c D D¹ so that the diminution of length of
the path D D' is exactly equal to the quantity wound on the bobbin D¹ and
consequently there is a stoppage of the film between the points cc and a definite
exposure. The position of the opening on the disc is adjusted so that the image
is produced on the film during this stoppage, the value of which is exactly
known.
This arrangement is advantageous when long lengths of sensitized film are
acted upon.
To insure the stoppage of the bobbin D at the same time that the winding
bobbin D' itself is stopped so that the film may be uniformly extended whilst its
sensitized surface receives the impression of the light, the pressure on the spring b
is varied being greater at the moment of stoppage of the film or even a little
before this stoppage and less between the stoppages so that the movement of the
film then becomes more free. In order to obtain this result the strap of the
eccentric e is provided with a pin which is jointed to the free end of the band
spring and makes the latter exercise a stronger pressure on the plate a at the
moment desired for the stoppage.
:
From these arrangements it results that the passage of the openings on the
disc B coincide exactly with the moments when the film C is stationary and with
the maximum friction exerted on the bobbin D. These three conditions are the
best to ensure the distinctness of the images which are thus thrown on a stationary
and stretched film.
In order that the taking of the images may be readily regulated, the shutter
disc made of sheet iron and actuated by any desired motor or simply by hand, has
a mass sufficient to give it the capacity of a fly wheel and at the commencement
of the operation rotates alone with its axis and it is only when it is desired to
commence taking images that its axis is put into gear with the rest of the apparatus.
The clutch gear consists of a projection 9 rotated with the axis and which engages
in an opening of a plate H connected to the bevel wheel R actuating the inter-
mittent mechanism. The disc B is fixed on the axis O and is actuated by the
movement of a band, chain or gearing which acts ou a pulley P, M being the
motive axis. The axis O carries fitted thereto a plate G which turns with it and
on which is the pin g. Opposite the plate G is another plate H with a slot / which
is connected to the bevel wheel R and is free to turn and also to slide on the
axis O. A spring K acts on the end of the axis and when this spring exerts its
pressure and thrusts forward the axis O, the disc B with its axis O and the plate G
approach the plate H and the pin y enters the sloth and the movement of the
,,

page_text: system takes place immediately. The coincidence of the stoppages of the film with
the passages of the openings of the disc is also secured since the bevel wheels R R'
are always engaged.
The engagement is effected by hand by means of the crank L which by means
of a small cam k with inclined plane, presses in its position of rest on the extremity
of the axis O and destroys the action of the spring K: on the contrary it allows.
this spring to act when this crank is turned so as to present against the axis a
projection smaller than the cam k.
On the axis of the crank L is fixed a shutter N formed of a thin sheet of steel,.
the shutter N prevents the light from penetrating into the apparatus as long as the
engagement does not take place so that the passage of light and unwinding of the
film are rendered absolutely simultaneous. The film once passed on to the bobbin D¹
is protected by the paper which forms its extension and a spring m prevents its
unwinding.
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 :
1. A photographic apparatus for taking a series of photographic images on a
continuous film at equal and very close intervals consisting of a continuously
revolving shutter and of a sensitized band traversed intermittently by being
wound on a bobbin geared to the shutter substantially as described.
2. In a photographic apparatus in which a series of photographic images are
adapted to be taken at equal and very close intervals on a continuous band or filni,.
the mechanism for giving the band an intermittent motion from a continuously
rotated part consisting of a bobbin mounted on an eccentric pin and on which the
band is to be wound, of a driving shaft with its eccentric pin or shaft and of
gearing for connecting the driving shaft to the continuously rotated part, substan-
tially as described.
3. In a photographic apparatus in which a series of photographic images are
adapted to be taken at equal and very close intervals on a continuous band or film,
the mechanism for giving the band an intermittent motion from a continuously
rotated part consisting of a shaft geared to the continuously rotating part and of a
winding surface on which the sensitized band is to be wound and which is so
shaped that at one or more parts the winding on is compensated by the decreased
length of path of the band so that the band is stationary, substantially as
described.
4. In a photographic apparatus in which a series of photographic images are
adapted to be taken at equal and very close intervals on a continuous band or film,
the mechanism for giving the band an intermittent motion from a continuously
rotated part consisting of a bobbin on which the film is to be wound and geared to
the continuously rotating part and of a winding surface continuously rotated and
on which the band bears and shaped so that at a certain part the amount of band
wound on the bobbin is compensated by the decreased length of path of the band, '
substantially as described.
5. In a photographic apparatus for taking a series of photographic images on a
continuous film at equal and very close intervals the combination with the
continuously revolving shutter and the sensitized band traversed intermittently by
being wound on a bobbin geared to the shutter, of a clutch gear adapted to connect
the revolving shutter and revolving bobbin always in the same phase, of a movable
shutter and of a means for simultaneously operating the clutch mechanism and the
shuttér, substantially as described.
Dated thie 10th dox of Denambar 1902
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.