Year: 1898

page_text: We, JOHN EDWARD THORNTON, of Rokeby, Altrincham, and THE THORNTON-
PICKARD MANUFACTURING COMPANY, LTD., Altrincham, in the County of Chester,
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to provide an improved construction of shutter
for photographic plate-holders, and an improved form of light trap or valve for
such plate-holders.
In carrying out the invention, we construct the shutter from a sheet of
aluminium which slides into grooves in the wooden frame of the plate-holder as
usual. The handle or top for withdrawing this shutter may be made of mahogany
or other material suitably finished and firmly attached to the end of the metal
shutter. In some cases we prefer to form the handle out of part of the metal
shutter itself. To do this the shutter is left extra long and the projecting piece
is turned back, so that the handle is a double thickness." The piece that is turned
over can be utilized to act as a spring catch for preventing the shutter being
accidentally withdrawn. This may be suitably carried out by making a 'hole or
notch in the bent over piece, that engages with the head of a round headed screw
or other suitable form of pin attached to the wooden frame of the plate-holder.
The bent over piece has sufficient spring to enable it to engage with this round
headed screw, but when the handle is gripped for withdrawal, pressure with the
thumb upon the bent over piece is sufficient to spring it clear of the engaging pin,
but a spring may be placed inside the double handle to increase the pressure if
required.
The shutter may be stiffened by making corrugated beads or lines across it.
Sometimes we make the bead across the inner end of the shutter, in which case
it forms a stop that prevents the shutter being entirely withdrawn from the plate-
holder. In other cases the bead may be formed on the outer end, near the handle,
and in that case the shutter may be entirely withdrawn if required.
The shutter may be finished off in various ways, but we prefer to finish it with
a matt or semi-bright grained surface, and to print or otherwise mark on the
surface suitable lettering and provide spaces for writing in particulars of the
exposure: the grained surface of the shutters provides a ready means for writing
on with lead pencil which can be easily erased. The inner surface of the shutter
(which comes opposite the sensitive plate) we prefer to finish a dull black with a
suitable varnish or other means. The outer surface may be finished in a similar
manner if preferred.

page_text: The light valve is constructed in the following way: -
The aperture or slot in the wooden frame of the plate-holder through which
the shutter passes is lined with plush, velvet, cloth, or other suitable material,
but we prefer to use a special kind of plush with long, closely woven, and stiff
pile. The top portion of the frame forming the slot is removable for convenience
in fitting the plush lining, and the said lining is glued or otherwise fastened into
grooves in the. wood-work specially provided for it. We prefer to use narrow
strips of the plush and to place one at the top and one at the bottom portion of the
slot, in such a position relative to each other that the pile of the two pieces of
plush shall pass and overlap each other, so that the slot is closed thereby and
light prevented from entering. In the shutter itself we form grooves or corruga-
tions in positions that will correspond with the strips of plush when the shutter
is pushed home in the plate-holder. Therefore, whilst the shutter is in position
the pile of the plush strips stands up and fits into the recesses provided for it in
the metal shutter. When the shutter is being withdrawn from or inserted
in the slot in the frame of the plate-holder, it pushes the pile of
the plush aside sufficiently to allow the metal shutter to pass, the pile of
the plush meanwhile rubbing against the surface of the shutter. It will
therefore be understood that all light is perfectly excluded in whatever position
the shutter is placed, whether partly drawn, not drawn at all, or drawn completely
out.
In practice, we find that it is sufficient to have two plush strips, one above and
one below, but if desired, three or more strips may be used, it being understood
that they are so placed that no single pair of strips are exactly opposite to each
other.
As a convenience and safeguard to obviate all chance of the metal shutter
cutting off some of the pile when first meeting the latter, we form a bevelled ridge
on the underneath surface of the top portion of the frame in such a position that
the front edge of the metal shutter gradually mounts this ridge before catch-
ing the pile as the shutter is being pushed in: therefore, the shutter is lifted towards
the top of the pile, in which position is has no cutting action.
It will be observed from the foregoing description that the form of the shutter
looking edgewise is that of a sinuous line at the end corresponding with the light
valve, and the entrance to the wooden frame which forms the light valve is also
made sinuous by reason of the plush, and therefore, as light only travels in a
straight line it cannot pass completely through the slot or valve and reach the
sensitive plate.
If desired, the shutter may be plain, made without corrugations or grooves
corresponding with the plush strips.
In plate-holders having slides or shutters of other thick materials than metal
(for instance, xylonite, ebonite, and wood) grooves instead of currugations may
be made in the shutters, into which the plush pile fits when the shutter is pushed
home.
Thin materials such as cardboard, very thin xylonite, &c., may be corrugated
same as the metal.
In cases where the shutter runs in an open groove instead of a slot (for instance,
a wooden shutter having its face level with the face of the wooden frame) one, two,
or more plush strips are fixed to the frame to press against the underneath side of
the shutter, and the latter is grooved for the plush to fit into when the shutter is
pushed home, and other grooves may be made at the other end of the shutter for
the plush to engage with when the shutter is drawn to its fullest extent.
Doted this 7th day of holmi 1808

page_text: Improvements in Photographic Plate-holders.
We, JOHN EDWARD THORNTON, of Rokeby, Oldfield Road, Altrincham, in the
County of Chester, Manufacturer, and THE THORNTON PICKARD MANUFACTURING
COMPANY LIMITED, of Altrincham; aforesaid, 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 photographic plate holders or dark slides and is
designed to provide an improved construction of shutter therefor and an improvedl
form of light tight trap or valve for the shutters thereof.
It consists essentially in constructing the shutter from a sheet of aluminium
with a suitable handle or top for actuating it and in forming a light tight trap
of sinuous form by corrugating or grooving the shutter opposite to the plush
attached to the holder so that the pile or nap of the plush or velvet or other
material may stand out when the shutter is closed.
The invention will be fully described with reference to the accompanying
drawings..
Fig. 1. Front view partly in section of plate-holder
Fig. 2. Longitudinal section of same.
Fig. 3. Section of aluminium shutter removed.
Fig. 3. Modified form of shutter:
or slide.
Fig. 4. Longitudinal section of plate holder or dark slide of book forni showing
invention applied to wooden shutter.
Fig. 5. Section of shutter removed.
In Figs. 1, 2, and 3 the shutter A is constructed from a sheet of aluminium and
slides in the grooves of the wooden frame of the plate-holder B as usual. The
top or handle C is made of mahogany or other wood or suitable material firmly
attached to the end of the aluminium shutter A. If preferred the handle may
be made of aluminium formed in one part with the shutter itself as in Fig. 3 the
top edge being turned over into the form of a ridge or bead or in the form of an
inverted U or otherwise. When the edge is thus turned over it may also be
utilized to. form or act as a spring catch to prevent the shutter being accidentally
withdrawn by making a hole or notch c therein to engage the head of a screw er
pin inserted in the top frame of the holder B. The bent over edge will have
sufficient spring to enable it to engage with this round headed screw, but when
the handle is gripped for withdrawal, pressure with the thumb upon the bent over
piece is sufficient to spring it clear of the engaging pin, but a spring may be
placed inside the double handle to increase the pressure if required.
The shutter A of aluminium may be. stiffened by corrugating beads or lines
across it (such as A Figure 3) either across the inner end of the shutter to form a
stop to prevent it being entirely withdrawn from the plate holder or at the outer
end near the handle or in other convenient position.
The aluminium shutter A may be finished off in various ways, but we prefer to
finish it with a matt or semi-bright grained surface; and to print or otherwise
mark on the surface suitable lettering and provide spaces for writing in particulars
of the exposure; the grained surface of the shutter provides a ready means for
writing on with lead pencil which can easily be erased. The inner surface of the
shutter (which comes opposite the sensitive plate) we prefer to finish a dull black
with a suitable varnish or by other means. The outer surface may be finished in
a similar manner if preferred.

page_text: A light tight trap or valve D is formed in the aperture a in the top of the plate
holder B through which the shutter A passes by strips d of plush velvet cloth or
other suitable material, preferably plush with a long stiff and closely woven pile.
The strips d of plush are glued or otherwise securely fastened into the grooves d
in the woodwork provided for the purpose the top portion b¹ of the frame being
removable for convenience in fitting the plush strips.
The strips d of plush are placed facing one another one being at the top and the
other at the bottom of the slot or aperture a so that the two strips may overlap
without one pressing down the pile of the other so that the slot is closed thereby
and light prevented from entering.
In the shutter A grooves or corrugations E are formed in position to correspond
with the strips d of plush when the shutter is completely closed. When the
shutter then is in position the pile of the plush strips & stands out into the
recesses provided by the corrugations E of the aluminium shutter. This prevents
the compression or laying flat of the pile during the greater period of the life of
the shutter and consequently increases the light preventing properties and the
durability of the light tight valve D.
When the shutter is being withdrawn from or inserted in the slot in the frame
of the plate-holder it pushes the pile of the plush aside sufficiently to allow the
metal shutter to pass, the pile of the plush meanwhile rubbing against the surface
of the shutter. It will therefore be understood that all light is perfectly excluded
in whatever position the shutter is placed, whether partly drawn, not drawn at
all, or drawn completely out.
In practice we find that it is sufficient to have two plush strips, one above and
one below, but if desired three or more strips may be used, it being understood
that they are so placed that no single pair of strips are exactly opposite each
other.
If desired the shutter may be plain, made without corrugations or grooves
corresponding with the plush strips, or a metal shutter other than aluminium or
shutter of other thin material such as cardboard, thin xylonite or like may
be made with corrugations such as E to receive the pile of the plush strips d.
Where the shutter A¹ is made of wood, xylonite, ebonite or other material
thicker than sheet metal instead of corrugations a groove E¹ is cut therein into
which the pile of the plush strip d stands out when the shutter is closed.
In Fig. 4 the shutter A¹ is shown running in an open groove in a dark slide or
plate holder of book form one, two or more plush strips are fixed to the frame to
press against the underside of the shutter and a groove E¹ is cut in the shutter
for the plush to stand out into when closed. If desired the grooves may be made
at the other end of the shutter for the plush to engage with when the shutter is
drawn out to its fullest extent, thus the same effect of a sinuous opening is main-
tained with this construction, and light prevented from entering.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed we declare that what
we claim is
1. In a photographic plate holder a shutter of sheet aluminium, sheet metal,
cardboard, xylonite or other thin material formed with corrugations into which
the pile of the plush strips will stand out when the shutter is closed to preserve
the plush substantially as described.
2. In a photographic plate holder a shutter of wood, xylonite, ebonite or other
material constructed with a groove into which the pile of the plush strips will
stand out to preserve the plush substantially as described.
3. In a photographic plate holder a shutter formed of sheet aluminium with the
handle C formed in one part therewith by turning or bending over the top edge of
the shutter substantialy as described and shown with reference to Fig. 3.
4. In a photographic plate holder a shutter constructed substantially as de-
scribed with reference to either of the figs. of the drawings.

page_text: 5. In a photographic plate holder a light tight trap or valve constructed by two
or more strips of plush placed so as to overlap one another substantially as de-
scribed and shown.
6. In a photographic plate holder a light tight trap or valve constructed by one,
two or more strips of plush in combination with a corrugated or grooved shutter
substantially as described and shown.
is 14th day of October. 1898.
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.