Year: 1885

page_text: Сашогар.
I ALEXANDER MELVILLE CLARK, of the firm of A. M. & W Clark of 53 Chan-
cery Lane in the County of Middlesex, Fellow of the Institute of Patent Agents
do hereby declare the nature of this invention to be as follows:-
=
My Invention relates to an improved photographic dark back or slide for
containing negative paper, or film tissue in the roll or continuous length, and it
has for its object to provide means whereby the operations of drawing the
successive portions of the paper or film into position for exposure in the camera,
and of perforating or marking the film or paper at intervals corresponding to the
portions successively exposed, will be performed automatically by the movement of
the dark shutter.
According to one arrangement the paper or film is drawn into position for
exposure by a pair of drawing rollers actuated from the shutter by rack motion,
the paper passing between the rollers. The rollers are preferably actuated by the
movement of the dark shutter in both directions, the paper being moved one half
the distance it is required to travel by the inward movement, and the second half
by the outward movement of the shutter. For this purpose the rack motion would
be directly in gear with the one roller on the outward movement, and with the other
roller on the inward movement of the shutter, the rack motion not in gear running
idle by means of pawl and ratchet gear.
These rollers would be situated at one side or end of the aperture closed by the
dark shutter, and suitable means would be provided for maintaining the tension of
the paper which might be stretched across a plane surface to support it in a
perfectly flat condition. A spring barrel would be provided for winding up the
paper as it is delivered by the rollers, or the said barrel may take its motion from
the feed or other rollers.
Instead of dividing the travel of the paper between the inward and outward
movements of the shutter, it may be moved by the one or other of these movements
only.
Another means of performing this operation consists of a self acting clip mounted
at the back of the dark shutter, through which the paper passes, the clip being so

page_text: constructed as to grip the paper automatically on the movement of the shutter in
one direction only, so that the paper is thereby carried along with the shutter when
moved in that direction, and remains stationary when moved in the other direction.
This clip extends across the strip or web of paper and it may be plain or have a
serrated edge for the purpose of perforating the paper transversely to facilitate
the subsequent division into lengths corresponding to the portions successively
exposed.
Another means of perforating the paper consists of a row of punches and a
corresponding bed die, between which the paper is caused to pass, the perforating
mechanism being actuated at the proper moment by the shutter for the purpose of
perforating or marking the paper, either completely across or at the edges only, so as
to enable it to be readily divided at the proper places.

page_text: latter will be prevented from curling forwards. f f are anti friction rollers
journaled in the plates E to relieve the strip of undue strain in passing over the
ends of the plate F. P is the strip of sensitive paper or tissue wound upon spools or
rollers G, H, H being the letting off spool and G the taking up spool. The strip is
attached to these spools in any convenient manner as for instance by tucking the
end of the strip into a groove in the spool and retaining it therein by a wire whose
ends are inserted in holes in the end flanges of the spools. These spools are
journaled in the plates E of the inner frame and on one end of their axes are keyed
pulleys gh on which runs an endless india rubber or other band for the purpose of
transmitting motion from the letting off to the taking up spool the ratio of the
diameters of these pulleys being such that when the let-off spool is full and the take
up spool empty the latter will wind on as fast as the other lets off, the varying
ratio between the spools as the strip becomes transferred from the one to the other
being allowed for by the slipping of the band which at same time acts as a brake
to put the necessary tension on the sensitive strip.
So far, the arrangements are similar whichever mode of transmitting motion
from the shutter to the paper or film may be adopted.
In the arrangement represented in figures 1 to 4 the sensitive strip is drawn past
the aperture CC by a pair of india-rubber covered drawing rollers I K actuated
by rack motion from the shutter D. In the arrangement shown the strip is moved
one half the distance it is required to travel after each exposure by the inward
movement of the shutter the second half of the travel being accomplished by
the outward movement of the shutter both rollers being actuated directly by
the shutter the one on its outward and the other on its inward movement, the
action of the rollers however being the same at each stroke of the shutter the
rollers turning in opposite directions as indicated by the arrows either by friction
the one from the other or by the two rollers being geared together by equal pinions.
These rollers are journaled in the plates E of the inner frame and are actuated by a
pair of racks L fixed to the rear face of the shutter in the direction of its line of
motion these racks passing alongside the free edges of the inner or false front A¹
and in gear with toothed wheels i k running loose on opposite ends of the axes of
rollers IK respectively. Ratchet-wheels are pinned or keyed on the same
ends of the said axes immediately alongside the wheels ik to which are pivoted
spring pawls that engage with the ratchet wheels. This rack ratchet and pawl
gear is situated between the casing and the plates E of the inner frame and being
applied to opposite ends of different rollers the one runs idle whilst the other is in
work and vice versa. In order to facilitate the introduction of the sensitive strip
between the rollers I K one of them may be removable by journaling it in slot
bearings closed by hooks bolts and removable blocks as shown in figures 5 and 6
or otherwise. These rollers I K are represented as being situated at one side of the
plate F which as before mentioned corresponds to the oblong aperture C and the
strip is therefore drawn across the aperture in the direction of its width but
the relative position of the aperture to the rollers and gear might if desired be
such that the strip will be drawn past the aperture C in the direction of its length.
In the arrangement shown the ratio of the diameters of rollers I K to their
respective wheels ik is as 1 to 2 but I do not limit myself to this proportion as
the rollers are not necessarily of equal diameters and it might be desirable that the
strip should be made to travel a greater distance on the inward than on the
outward motion of the shutter in order that the multiplication of power obtained
by the ratio of the gear to the rollers shall be greatest on the outward stroke of
the shutter so as to avoid all liability of disturbing the camera after focussing.
Again instead of moving the paper at a single complete stroke in and out of the
shutter the gear might be so proportioned that two complete strokes of the shutter
are required to shift the strip to the requisite extent. On the other hand instead
of dividing the travel of the strip between the inward and outward movements of
the shutter it may be moved by the inward movement only. In this case the two
racks would gear with spur wheels i loose on the two ends of the same roller I

page_text: each gearing therewith by ratchet and pawl gear acting concurrently in the same
direction the duplicate racks being preferably retained to prevent any tendency to
cause the shutter to cant in its grooves.
Figure 7 illustrates a modification of this last described arrangement wherein the
strip is actuated only at the inward stroke of the shutter which is made to act as
its own rack the drawing rollers being made to release their nip of the strip on the
outward stroke of the shutter instead of using the ratchet gear. In this case the
shutter gears directly by friction with roller K and at same time presses it into
frictional contact with the strip so as to cause the strip to be nipped and drawn
between the rollers I K on the inward motion of the shutter; the roller K being
moved away, and running free of the strip on the outward stroke of the shutter.
For this purpose the roller K is journaled in spring arms k³ fixed to frame E which
tend to press the roller K between the shutter and the other roller, the relative
diameters and positions of the rollers being such that the movable roller will tend
to jam itself between the shutter and the other roller on the inward stroke and so
cause the strip to be tightly nipped.
In order to indicate where the strip is to be divided for the purpose of developing
the portions successively exposed, a perforator or marker and a corresponding bed
are provided between which the strip is caused to pass, the same being in such a
position that the line of demarcation between two exposures will be in register
therewith when the shutter reaches the end of its inward stroke, at which moment
the device is actuated by the shutter for the purpose of perforating or marking the
strip either completely across, or at the edges only so as to enable it to be readily
divided at the proper place. In Figures 1 to 4 the perforating or marking device
consists of a pair of springs M fixed to the side of the case A and having serrated
ends or points m (or it may be carrying a serrated blade extending entirely across
the strip) the points being directed towards the roller K which in this instance
serves as the bed, these springs being pushed inwards against the strip passing
round said roller by a projecting rib d fixed to the back of. the shutter striking
against pins m¹ sliding through holes in the side of the case A and abutting against
the rear of the springs M at their free ends Instead of using the roller K however
a separate fixed rubber faced bed might be used as would be the case in figure 7 in
which figure the arrangement would differ somewhat from that in the previous
figures on account of the different course which the strip takes around the rollers.
Figures 8 and 9 represent another means of performing both the operations of
propelling and perforating or marking the strip. It consists of a clip formed by a
blade N extending across the whole width of the strip and pivoted in brackets n
at the back of the shutter D the strip passing between the serrated free edge of the
blade and an elastic bed on the back of the shutter. The blade is pressed lightly
against the back of the strip by a spring, and on the inward motion of the shutter
the blade acting as one member of a toggle its serrated edge becomes embedded in
the strip which is gripped firmly between the blade and the bed on the shutter so
as to be carried along with the latter. On the outward stroke, the blade slides
freely against the back of the strip which then remains stationary.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim is;
1. A dark back or "roller slide" for photographic cameras wherein motion is
given to a sensitive strip of paper or tissue by the motion of the dark shutter sub-
stantially as specified for the purpose of successively exposing consecutive portions
of its surface.
2. In a dark back or "roller" slide for photographic cameras, the combination
with the shutter of a pair of drawing rollers acting on the sensitive paper or strip
in the manner described and of rack ratchet and pawl gear for giving rotary
motion to the rollers by the rectilinear-motion of the shutter either in one or both
directions and of suitable mechanism for unwinding and winding up and distending

page_text: the strip of sensitive paper or tissue, substantially as described and illustrated in
figures 1 to 4 of the drawings.
3. In a dark back or "roller slide" for photographic cameras, the combination
with the shutter of a. pair of drawing rollers acting on the sensitive strip in the
manner described, the one roller gearing directly with the shutter by frictional
contact substantially as described and illustrated in figure 7 of the drawings.
4. In a dark back or "roller slide" for photographic cameras the combination
with the shutter of a device for perforating or marking the sensitive strip in
accurate register with the successive exposures, said device being actuated directly
by the shutter itself substantially as specified
5. In a dark back or "roller slide" for photographic cameras, the combination
with the shutter of a gripping device or clamp so applied as to be caused to grip
the sensitive paper or strip during the one movement of the shutter and carry it
along the required distance and leave it free during the other movement of the
shutter, the said device serving also to mark or perforate the strip, substantially as
specified.
6. In a dark back or "roller slide" for photographic cameras in which the
sensitive strip is propelled by the shutter in its motion acting directly or indirectly
ou the strip, gearing together the letting off and taking up spools so that the latter
shall be actuated by the uncoiling of the strip itself and the necessary tension be
applied substantially as specified.