Improved Double Metallic Carrier or Slide for Photographic Plates.
Year: 1897

page_text: Date of Application, 15th Apr., 1897-Accepted, 22nd Jan., 1898
COMPLETE SPECIFICATION.
Improved Double Metallic Carrier or Slide for Photographic Plates.
I, EMIL WÜNSCHE, of Marschall Strasse, 39, Dresden, in the Kingdom of Saxony
and Empire of Germany, Manufacturer of Photographic Plates, 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 double slides or plate carriers now generally used on account of the saving
in space thereby obtained, are subject to a defect as regards their being permanently
light-tight, which defect is as follows:-
The holder or carrier receiving the sensitised plates is slid into the frame of the
slide containing the aperture for exposure covered by a sliding shutter. In order
to insert or remove a plate the holder has to be pulled out from and inserted again
into the frame of the slide.
At the part where the carrier is inserted, and for the purpose of protecting the
plate within against light, means are provided to exclude light, the surface thereof
is of velvet, which is the material used for excluding light in all such photo-
graphic apparatus.
Owing to the repeated insertion and removal of the light-excluding device, firmly
connected with the plate-holder, the velvet naturally becomes worn away at the
points of contact, and hence its capacity for excluding light diminishes. To pre-
vent this and to ensure perfect exclusion of the light, notwithstanding the un-
avoidable wear of the velvet, wide contact-surfaces of the velvet are provided with
an elastic backing. This, constantly pressing on the velvet, takes up the wear
and keeps the parts light-tight.
At the narrow contact surfaces however where means for compensating the wear
of the velvet cannot be applied, the consequences of such wear become perceptible
in time, light penetrating to the plates and rendering them useless. When this
takes place, the slide can no longer fulfil its chief object, that of protecting the
plates it contains against light.
The object of the present improvement in metal slides is so to perfect the same,
that they will remain permanently light-tight in all parts. For this purpose this
slide is so arranged, that the means for rendering the narrow contact-surfaces light-
tight are not subject to wear at all.
To this end the following arrangement is adopted in the slide shown in the accom-
panying drawings in which:-
Fig. 1 is an elevation.
Fig. 2 vertical section.
Figs. 3 and 4 front elevation and side elevation of the removable part of the
slide.
Figs. 5 and 5* horizontal sections.
Fig. 6 a vertical section of the slide when closed.
The frame of the slide consists of two parts. One part a, shown in Figs. 1 and 2,
slides into the other part b, shown in Figs. 3 and 4. When the one is inserted into
the other three edges of the same are made light-tight either by causing the bent
edges of the one part b, to embrace the other, a, as represented in Fig. 5 or by
D
01

page_text: providing tongue a' on the part a as shown in Fig. 5 which engage with grooves
in the part b.
At the fourth edge of the slide frame light is excluded by the light-excluder d
permanently attached to the frame by the support d', the light-excluder is elastic
and its elasticity causes it always to bear against the corresponding surfaces of the
slide or against the shutters e, e¹, between said surfaces and the excluder as seen
in Fig. 6, thereby always excluding the light. This light-excluding device d,
being fixed on the part a, it is immovable and its narrow contact surfaces are there-
fore not subject to wear. As no wear can take place the passage of light at this
part is permanently prevented.
The holder c for carrying the sensitised plates is at its upper edge hinged to the
part a of the frame, (see Figs. 2 and 6). To place plates in the slide, or to remove
the same, the part b is pulled off the part a and the lower end of the holder lifted
as shown in dotted lines Fig. 2. At this end the holder is open to permit insertion
and removal of the plates.
The apertures for exposing the plates provided in the frame are closed by the
shutters ee which slide upwards.
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:
A double slide of metal for photographic plates characterised by being con-
structed with a frame the two parts a and b whereof slide into one another, the
plate holder c being hinged to the one part a, said part a showing the light ex-
cluder d connected therewith by the support d for the purpose of preventing wear
of the contact surfaces of the light excluder and thereby avoiding the loss of light-
excluding power arising from wear.
Dated the 15th day of April 1807
NEWNHAM BROWNE,
Agent for the Applicant.