Improvements in Photographic Film Holders or Dark Slides for Sensitive Surfaces on Pliable Supports.
Year: 1899

page_text: Date of Application, 12th Dec., 1899
Complete Specification Left, 11th Sept., 1900-Accepted, 20th Oct., 1900
Improvements in Photographic Film Holders or Dark Slides for
Sensitive Surfaces on Pliable Supports.
I, JOHN RUDOLPH GOTZ, of 215, Shaftesbury Avenue, Optician &c., London,
W.C., do hereby declare the nature of this invention to be as follows:-
My invention has for its' object the better and easier adjustment for exposure
in the camera of pliable sensitive films on paper celluloid or any other support.
The film being stretched or pressed onto a flat basis by means of springs applied
in and acting on the rabated part of the holder.
In the ordinary dark slide or plate box the plane of focus or focal plane has
always been laid in the depth of the rabate of the frame & the plate or the
film with its carrier was pressed by springs acting from behind the plate pressing
it forward into register. By this invention the inverse plan is followed. the
focal plane
on a level with the solid back of the slide & the sensitive surface
which is very thin is pressed or held down on to it by the springs inserted along
the rabated frame thereby pressing the film into register from the front. By
this means I can dispense with the so called film carrier the necessity of which
up to now sensibly diminished the advantages arising from the use of films or
flexible sensitive surfaces generally because the carrier added to the weight of
the apparatus.
The principle of my invention rests on this fact that the springs which are
to hold the sensitive film in the focal plane are applied on the edges & press the
film onto a rigid support or back, a plan which makes it possible to dispense
with carriers thus saving considerable weight as well as space.
Conditions which will make the use of films much more general than has been
the case hitherto.
Improvements in Photographic Film Holders or Dark Slides for
Sensitive Surfaces on Pliable Supports.
1, JOHN RUDOLPH GoTz, Manufacturer, of 215, Shaftesbury Avenue, in the
County of London, 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 an 1 by the following statement:-
The usual method of bringing a sensitive surface up to "register" in a
photographic dark slide or in a magazine holding a number of such sensitive
.

page_text: surfaces, has hitherto invariably been by pressure applied from the back of
such surfaces, as for instance in the case of glass plates.
These are pressed against a rebate in the slide or box, into which they are
laid for exposure in the camera.
The introduction of flexible supporting plates, made of paper, celluloid, or
other material, has given rise to many devices for suitably exposing the sensitive
surface, but when exposed in the ordinary dark slides, they had to be uniformly
supported at the back by a so called carrier frame or stretcher, into which they
had to be inserted for exposure, so as to bring the sensitive surface to bear against
the rebate which coincided with the plane of the focus of the lens.
This method of mounting precluded their general application in connection
with dark slides or holders carrying only one or two films.
The present invention relates to a new method of holding the sensitive material,
(such as paper, gelatine or celluloid), the latter being pressed back on to a solid
support on which it rests for exposure, and the plane of the focus being laid not
against a rebate, but just in front of the said solid support, allowing for the
thickness of the material carrying the sensitive surface.
By this means the use of a so called carrier is avoided, and the sensitive film
is held in the slide, without any such device as a stretcher or frame or whatever
the special carrier may be called.
In order to accomplish this, I construct either a single or double dark slide,
preferably the former, consisting of a frame with a drawer at the back, which
latter serves as the solid support for the sensitive material.
In the accompanying drawings, Fig. 1 is a back view, Fig. 2 a longitudinal
section, and Fig. 3 a cross section of a single dark slide embodying my invention.
Fig. 4 shows a clip or gripping device and Fig. 5 a holding down spring on a
larger scale.
a represents the body or frame of the dark slide, b the sliding
support or drawer, which Figs. 1 and 2 show partly drawn out and broken off,
in order to show the parts situated behind it.
If a film or sheet of paper, celluloid or similar material, were inserted into
the slide without any other support, the drawer or sliding door would, in the
act of closing carry the film with it, and thus displace it from its required
position.
I therefore insert into the frame a of the slide, a gripper & having two or more
small teeth and over that a plate e acting as a spring, so that when the
sliding door is closed, the plate e presses the film e on to the teeth of the
gripper plated and holds it in the proper position, as indicated by Fig. 4.
The sensitive film e is inserted with its front edge into the gripper, which, as
soon as the drawer or sliding door b is being closed, holds the film firmly in its
right place.
In order to keep the sides of the film in contact with the rigid sliding door,
spring are used, which may be of various descriptions, their object being in all
cases to hold the film down on to the rigid drawer; that is to say, in a direction
opposite to that of the springs usually applied in dark slides.
These springs are inserted into the rebates a¹ and body a of the slide, one or
more being placed on each side of the same.
Several forms of springs have been used with success, but I prefer to use a pair
of metallic springs f, f inserted into the body a of the slide and coming out flush
with the rebate a¹, which is cut away to make room for the spring, as shown in
detail by Fig. 5. Each of the springs f has a turned-over edge f¹ with one or
more teeth to hold the sensitive film on to the rigid surface of the sliding
door b.
The springs represented by the drawings have proved most satisfactory in
practice; I do not, however, limit myself to that particular form, but wish to
include other spring devices which act in the same manner.
is the ordinary
front sliding door, which is withdrawn for exposing the film.

page_text: 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. In a photographic dark slide or film holder, the combination of a slide body
or frame forming a rigid support or abutment for the flexible sensitized material,
with a system or springs secured to the said frame and adapted to press the
sensitized material against the said support, substantially as described.
2. In a photographic dark slide or film holder, a gripper adapted to hold the
film firmly in position, while the slide is being closed, and also during exposure
substantially as described.
3. A photographic dark slide or film holder adapted to hold a flexible sensitized
sheet or film in the manner substantially as described, without the aid of a
carrier or stretcher of any kind.
Dated this 11th day of September 1900.
FAIRFAX & WETTER,
Agents,
37 and 39, Essex Street, Strand, London,