Improvements in Dark Slides or Plate Holders for Photographic Cameras.
Year: 1894

page_text: Date of Application, 18th Dec., 1894-Accepted, 19th Jan., 1895
COMPLETE
SPECIFICATION.
Improvements in Dark Slides or Plate Holders for Photographic
Cameras.
We, JOHN EDWARD THORNTON, and EDGAR PICKARD, of Altrincham, near
Manchester, in the County of Chester, Manufacturers, 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 relates to dark slides or plate holders for the sensitive plates by
which they are placed in and removed from photographic cameras and is designed
to render such holders more efficient in holding the plates and the operation of
inserting the plates therein and withdrawing them therefrom, more convenient.
It consists essentially in constructing that part of the frame into which the plate
is inserted, with a fixed ledge on every side between which the plate is placed and
fitting closely thereto with a rabbet or under cut recess at the top edge and a
movable strip or spring bar at the bottom to slide over the fixed ledge to form a
groove or recess at the bottom.edge a spring or springs being placed below the
same and with a spring or springs to press the plate outwards when released and
render it casy of being handled or taken hold of.
'
It will be fully described with reference to the accompanying drawings in which
as an example a double slide is illustrated.
Fig. 1, is a front elevation partly in section with the slide and sensitive plate
removed.
Fig. 2, is a transverse sectional elevation with the sensitive plate and slide in
position at one side and the slide removed and the plate partly removed at the
other side.
Fig. 3, is a sectional plan with the plate and slide in position at one side and
removed at the other side.
The external frame A is made in any convenient way with the corners dovetailed
or otherwise secured together and is provided with slide B a central diaphragm or
division plate C sensitive plates D and light excluding strips F pressed outwards
by springs fall constructed of any ordinary or convenient shape.
We construct the frame A with a fixed ledge a at each side of the space into
which the plate D is to be inserted; at the right and left of the space the fixed
ledge a is formed by the sides of the frame; at the top it is formed by the rabbet
or groove G cut in the frame A which also provides a projection 9 under which
the edge of the plate can be inserted; at the bottom it is formed by the fixed piece
or bar K. In front of and sliding over the fixed piece or bar K we place a spring
bar E. The spring bar E is capable of moving to and fro over the surface of the
fixed piece or bar K and when pushed outwards from the frame A forms a groove
or recess for the bottom edge of the plate D. When the sensitive plate D is in
the holder the normal position of the spring bar E is that shown in Fig. 1 and left
side of Fig. 2. It is held in that position by the spring L and the pins M.
The ends of the spring bar E slide in grooves m cut in the sides of the
frame A.
On the centre diaphragm or division plate C we place a spring or springs H
which hold the sensitive plate D against the projection and the spring bar E
to prevent it moving or shaking and to hold it in focus. When the spring bar is
moved past the edge of and out of contact with the plate D and level with the edge
of the fixed bar K the springs H cause the sensitive plate to move or spring
outwards at the bottom edge so that it may be easily taken hold of.

page_text: The outer edge of the spring bar E may be if desired bevelled to the correct
angle so that by pressing the plate D down upon it it will be caused to slide back
and permit of the plate being inserted between the rigid ledges a.
To insert the plate D-in position in the holder the top edge is first passed behind
the projection 9 and inserted in the groove G the lower edge is pressed down
compressing the springs H. The spring bar E is drawn back and the edge of the
plate is brought to position in front of the edge a of the fixed bar K the spring
bar E is then moved back to its normal position by the spring L covering the edge
of the plate and holding it in position. The plate is released and removed by the
reversal of these movements.
•
We are aware that dark slides and plate holders have been constructed with
sliding spring bars which abut against the edges of the plates to adapt them
to variations of size and to secure the plates in position and such we do
not claim.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
:-
1. In a dark slide or plate holder for photographic cameras the combination
with the frame A provided with rigid ledges a the slide B, the light excluding
strips F, the projecting piece g forming the groove G, of the fixed bar K against
the rigid edge of which the sensitive plate D rests and the spring bar E which
slides upon the surface of the fixed bar K and overlaps the edge of the plate to hold
it in position substantially as described.
2. In a dark slide or plate holder for photographic cameras the combination of
the frame A the slide B, the central division plate C, the light excluding strip F,
the projection g forming the groove G to receive the top edge of the plate D, the
fixed bar K forming a rigid ledge for the bottom edge of the plate to rest against,
the spring bar E sliding over the surface of the fixed bar K and overlapping the
edge of the plate to secure it in position, the spring L to move the spring bar in
one direction, the pins M to control the movement of the spring bar and the
springs H to prevent movement of the plate and force it outwards when released
substantially as described.
Dated this 17th day of December 1894