Apparatus for Changing Sensitive Photographic Plates and Films (without Consequent Exposure to Light) Before and After Exposure in the Camera.
Year: 1896

page_text: Date of Application, 21st Jan., 1896
Complete Specification Left, 19th Sept., 1896-Accepted, 21st- Nov., 1896
PROVISIONAL SPECIFICATION.
Apparatus for Changing Sensitive Photographic Plates and Films
(without Consequent Exposure to Light) Before and After
Exposure in the Camera.
I, JOHN BIDGOOD, of 26 Saltwell View, Gateshead, Teacher do hereby declare
the nature of this invention to be as follows:-
The apparatus consists of two parts :-
(1) A plate hox furnished with wood or metal grooving on two opposite sides into
or out of which the plates or films may slide. This box is provided with a sliding
cover across which is cut a slot the width of the plate or film, and by sliding the
cover along the box this slot may be placed opposite any particular plate or film it
may be desirable to use or return to its place.
Over the slot in the cover is fastened, by means of a flange attached to it, an
oblong projecting piece of metal with a slot of the same size at that in the cover cut
through it. This I call the loader.
Working across the slots and between the flange of the loader and the cover of the
box is a diaphragm of sheet metal which may be kept in position by springs in such
a manner that ordinarily the slots are closed by it. This diaphragm may however
be pressed back against its springs so allowing a passage through the slots, and then
any selected plate or film, opposite which the slots are placed by sliding the cover,
would fall out on inverting the box.
I prefer to actuate this diaphragm in the following manner. Passing through slots
cut in the flange on one side of the loader, and attached to the edge of the diaphragm,
are two metal wedges. These are so placed that when the side or end of the dark
slide or its equivalent, hereinafter described, is fitted on the loader, in the manner
hereinafter described, these wedges are pressed back against springs and carrying the
diaphragm with them open a passage for the plate or film. This passage is open so
long as the dark slide or its equivalent is on the loader. When it is withdrawn, the
diaphragm being pressed back into position by its springs closes the passage through
the slots, and the whole box is then light tight.
But the diaphragm may be unprovided with springs, and may in any case be
actuated by the hand.
(2) A dark slide of ordinary construction except in the following particulars:-
It is loaded with the sensitive plate or film, or unloaded, at an end or side by
allowing the plate or film to slide from the plate box into the position it occupies
during exposure, or vice versa. To allow this to be done without exposing to light
during the passage of the plate or film, at the loading end of the dark slide the
grooved cavity into which the plate passes is enlarged sufficiently for the loader of the
plate box to fit closely into it. Near the inner end of this enlarged portion a metal
diaphragm works across the cavity in such a manner that the cavity may be opened
to allow a plate to pass to or from the plate box, being closed again by springs
immediately afterwards.
I prefer to actuate this diaphragm in the following manner :-At each end of it is
a small lever, furnished with a spring, which can raise or depress the diaphragm.
The extremities of the levers come to the surface at the loading end of the dark slide.
When the dark slide is on the loader of the plate box a metal wedge on the flange of

page_text: the loader at.each-end presses down the extremities of the levers and so raises the
diaphragm. On separating plate box and dark slide the springs depress the diaphragm
and the dark slide is then light tight..
But this diaphragm may be unprovided with springs, and may in any case be
actuated by hand.
A spring at the back of the dark slide, and which may be controlled from outside,
brings and keeps the plate in register during exposure.
Instead of using a dark slide for the exposure of the plate, the portion of the
camera opposite the lens may be provided with a groove and diaphragm as described
for the dark slide, and the plate may be loaded directly from the plate box into the
camera.
Dated this 20th day of January 1896.
JOHN BIDGOOD..
COMPLETE SPECIFICATION.
Apparatus for Changing Sensitive Photographic Plates and Films
(without Consequent Exposure to Light) Before and After
Exposure in the Camera.
I, JOHN BIDGOOD, of 26 Saltwell View, Gateshead, Teacher, 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 :-
The object of this invention is to provide a changing box capable of containing a
large number of photographic plates, so constructed that any one of them may be
selected at will and passed into a dark slide or camera. back of special construction
and back again without exposure to light; to provide a dark slide or camera back
to receive the plates from the changing box; and to provide an appropriate means of
bringing and holding the plate in register during exposure in the camera.
Throughout this specification "plate" means tho. surface sensitive to light and the
vehicle carrying it.
In the drawings which accompany and illustrate my invention similar reference
letters indicate corresponding parts in all the figures. All the drawings are full size
for half plates, but the apparatus may be made to take any size of plate.
Fig. 1 is a front view of the upper part of the changing box with the cover
extension flap folded down on the box.
Fig. II is a plan of the sliding cover of the box with the extension flap lifted.
Fig. III is an end view of Fig. I but with the extension flap lifted.
Fig. IV is a portion of a section through X Y in Fig. III.
Fig. V is a plan of that end of the dark slide at which it is loaded.
Fig. VI is an end view of Fig. V.
Fig. VII is a portion of a section through dark slide and cover of changing box
showing the cover diaphragin being pressed back by the end of the dark slide.
Fig. VIII is a portion of a section through dark slide and cover of changing box
showing one of the diaphragm levers at the end of the dark slide being lifted by the
cam or wedge on the flange of the loader and carrying the diaphragm with it.
Figs. IX and X are section through and plan of the lever at the back of the dark
slide or camera which keeps the plate in register.
Figs. XI and XII are section through and plan of the rod with wedge-shaped end,
which working up and down at the back of the dark slide or camera forms an
alternative means of bringing and keeping the plate in register.
Fig. XIII is a section through X Y in Fig. Xll.
A is the changing box having divisions or grooves a a at each side to hold the
plates in position, and on one side a scale al along which a pointer all on the cover
slides and indicates at which plate the slot in the cover stops. On each side of the

page_text: Dox, near the top, is attached a metal rack a' which is clasped by the overlapping
edges of the cover and flap. The box is shown for twelve plates, but may be made
for more or less.
B is the sliding cover of the changing box, B' its extension flap hinged to the
cover by a continuous cloth hinge b. When the box is not in use this flap hangs
down close to the side of the box. It has a projecting shoulder b' which when
the flap is lifted in line with the cover, overlaps the edge of the cover and
together with the cloth hinge protects the junction from light. The cover and flap
may slide from end to end over the top of the box. It is prevented from sliding
completely off in one direction by permanent obstructions in one end. At the
other end are removable stops 61 which allow the cover to be slid completely off
when necessary in order to fill or empty the box.
Cis the overlapping edge of cover and extension flap. This edge has a grooved
cut on its inner surface which passes over the metal rack or guide a². This
arrangement keeps the cover and flap tight down on the top of the box but at the
same time allows both to slide freely along it from end to end.
Pivoted in each overlapping edge of the cover is a lever or pawl c which working
against a spring el keeps its inner extremity in close contact with the surface of the
rack a'. The teeth of the rack are cut at such an angle that the extremity of the
pawl passes easily over the teeth when the cover is pressed in one direction, but
the cover can be slid back again only by pressing down the outer extremities of the
pawls. The teeth also aré cut at such distances from each other as to bring the slot in
the cover of the box opposite a plate as the pawl passes over each tooth.
D is a slot through the cover of the box of sufficient size to allow a plate to easily
pass through it. By reason of the extension flap this slot can be brought opposite
any plate without uncovering the box.
Over this slot D is an oblong projecting piece of metal E with a slot through it of
the same size as that in the cover.
by a wide flange E'.
This is the loader which is attached to the cover
Between the loader and the cover of the box is a thin opaque diaphragm of metal F
which can work to and fro across the slots. This may be kept in position by springs f
in such a manner that ordinarily the slots are closed by it. The diaphragm may
however be pressed hack against its springs so allowing a passage through the slots,
and then any selected plate opposite which the slot is placed by sliding the cover
would fall out on inverting the box.
I prefer to actuate this diaphragm in the following manner. Passing through
slits in the flange on one side of the loader and attached to the edge of the
diaphragm are two metal wedges ff. These are so placed that when the end of
the dark slide, or camera if the plate is loaded directly into the camera, is fitted on
the loader in the manner hereafter described. These wedges are pressed back against the
springs ff and carrying the diaphragm with them open a passage for the plate. This
passage is open only so long as the dark slide or camera is on the loader. When it is
withdrawn the diaphragm being pressed back by its springs closes the slots and the
box is then light tight.
But this diaphragm may be unprovided with springs and be directly actuated by
the hand. In that case the wedges are replaced by smaller projections which can be
taken hold of and moved to and fro by a finger nail.
On the cover, furnishing a resistance to the springs of the cover diaphragm, and a
guide and support for the end of the dark slide when placing it on the loader is a
projecting piece G which may be of the size, shape and position indicated in the
drawings.
At the bottom of the changing box I place a thin layer of rubber, cloth, or felt, or
other soft material to protect the plate when falling into the box.
His a dark slide, to hold one plate, of ordinary construction except in the following
particulars.
It is loaded with the plate and unloaded at one end by allowing the plate to
slide by its own weight from the changing box into or out of it. In order to do

page_text: this, at the loading end of the dark slide the grooved cavity h into which the plate
passes is enlarged sufficiently for the loader of the plate box to fit closely into it.
Near the base of this enlarged portion a metal diaphragm h' works across the
cavity in such a manner that it may be opened to allow a plate to pass to or from
the box.
I prefer to actuate this diaphragm in the following manner. At each end of it is a
small lever L L working against a spring 1 which can raise or depress the diaphragm.
An extremity of each lever comes to the surface at the loading end of the dark slide
but does not project beyond it. When the dark slide is on the loader of the changing
box a metal wedge or cam on the flange of the loader at each end presses down the
extremity of the lever and so moves aside the diaphragm. On separating the
changing box and dark slide the springs move back the diaphragm and the dark slide
is then light tight.
But the diaphragm may be unprovided with springs and be directly actuated by
hand. In that case I bring each end of the diaphragmn to the exterior of the dark
slide, one on each side, and move it to and fro by the finger.
Instead of exposing the plates in a dark slide, the portion of the camera opposite
the lens may be provided with a groove for the reception of the loader of the box,
and a diaphragm as described for the dark slide, and the plate may then be loaded
directly into the camera and back again.
The method of changing the plates is as follows:-The cover of the changing box
is slid along until the slots in it are opposite the plate to be exposed. The end of the
dark slide or its equivalent is then placed on the loader, pressed home, and box and
slide inverted, and the plate falls into the dark slide or camera. To return the plate
to the box the inverse process is carried out.
If films are used in this apparatus it is better that each should be placed in a metal
or other carrier although this is not absolutely necessary.
In order to bring and keep the plate in register during exposure, I place in the
back of the dark slide or camera a pivoted lever M, one extremity m terminating in
a flat expansion, which prevents light passing through, coming to the outside; the
other m similar and on the inside. A spring under m' ordinarily keeps this
projecting a short distance into the cavity of the dark slide and so presses the
plate forward into register. At the time of loading and unloading however the lever
is pressed from the outside and the plate relieved from pressure.
An alternative means of accomplishing this is as follows:-Into the back of the
dark slide or camera I sink a thin flat rod of metal N terminating below in a wedge-
shaped piece n. This wedge has a projecting shoulder n² on each side which work in
grooves in the wood. When the rod and wedge are in the position shown in
Figs. XI-XIII their surface is flush with the back of the slide. The other end of
the rod is carried through the top to the outside. Immediately outside, a shoulder p
is formed on it, and the end p beyond the shoulder is wider and may be bent to
follow the curve of the top of the dark slide shutter. In this wider portion a hole is
drilled which snaps over a round-headed nail or screw in the top of the shutter.
stop g limits the motion of the rod in the direction of its length."
A
The action of this apparatus is as follows:-When the shutter of the dark slide is
closed the wedge is pushed home by the pressure of the top of the shutter on the
shoulder p. When the shutter is drawn if the wide end of the rod is grasped at the
same time as the top of the shutter, that also is drawn as far as the stop 9 will allow
it, or until the wedge n projects far enough into the cavity of the dark slide to press
the plate forward into register.
When no dark slide is used, and the plate is loaded directly into the camera, the
projecting end of this rod is moved to and fro by hand.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
(1) The grooved changing box with sliding cover and extension flap constructed

page_text: like the cover, hinged to it, and folding down on the box when not in use, substantially
as described.
(2) The grooved changing box with sliding cover with overlapping edges, the
edges being grooved on their inner sides to allow them to slide over the metal guides.
or racks attached to the sides of the box, substantially as described.
(3) The grooved changing box with sliding cover with overlapping edges,
carrying on each edge a pawl whose inner extremity moves over the teeth cut on
the surface of the metal guides or racks attached to the sides of the box, substantially
as described.
(4) The grooved changing box with sliding cover with overlapping edges, with a slot
through the cover large enough for a plate to pass through, the slot being covered by
the loader herein fully figured and described, and the box defended from light passing
through the slot by a thin diaphragm working between the loader and the cover of
the box, substantially as described.
(5) The dark slide, or camera when the plate is loaded directly into this, with
the thin diaphragm protecting its contents from light, raised and lowered by a lever
at each extremity, and actuated when pressed down on the loader of the changing
box by cams or wedges on the flange of the loader substantially as described.
(6) The dark slide, or camera when the plate is loaded directly into this, with
levers such as M, or rods such as N for holding the plate in register during exposure,.
of construction and mode of working substantially as described.
(7) The combination of the changing box substantially as specified, figured and
described, with a dark slide or camera substantially as specified, figured and
described, and the general construction and arrangement of the parts of each
substantially as specified.
Dated this 18th day of September 1896.
JOHN BIDGOOD.