Improved Apparatus for Coating Photographic Plates.
Year: 1890

page_text: Date of Application, 7th Jan., 1890
Complete Specification Left, 24th Mar., 1890-Accepted, 3rd May, 1890
PROVISIONAL SPECIFICATION.
Improved Apparatus for Coating Photographic Plates.
We; FRANK BISHOP, of the firm of Marion and Company, of 22 and 23 Soho
Square, in the County of Middlesex, Dealers in Photographic Materials, and
ALEXANDER COWAN, of Chase Side, Southgate, in the County of Middlesex,
Manager of Marion's Photo-Works, Southgate, do hereby declare the nature of this
invention to be as follows:-
:-
This Invention relates to improved apparatus for coating photographic plates with
sensitive emulsion.
The Invention relates first to the construction and mode of mounting of the coating
trough, and has for its object to ensure the even distribution of the sensitive emulson
and enable the thickness of the deposit to be easily regulated.
The trough is V-shaped in cross section and is constructed of two strips or
plates of glass or other suitable material, the one forming the inclined bottom side
of the trough being bedded upon a hot water circulation chamber and the other form-
ing the upright side of the trough being clamped in position with regard to the first-
mentioned plate, its lower edge being truly ground at a suitable angle and set at such
a distance from the surface of the bottom plate as to regulate the escape of
the emulsion, and allow it to flow in an even stream down the lower projecting part
of the bottom plate. The ends of the trough are closed by blocks which assist to hold
the two plates or strips in proper relative angular position. The hot water chamber
extends the whole length of the trough. and to it are fixed at intervals clamps
having set screws adapted to hold the plates forming the two sides of the trough in
their proper relative position at all points of their length. The trough is supported
by the ends of the hot water chamber being seated on balanced levers mounted to
oscillate at the sides of the coating table over which the trough extends, the lower
edge of the inclined side of the trough resting lightly on the plates to be coated as
they are carried beneath it upon the coating table.
In the case of a long trough a lip formed by a strip of flexible material interposed
between the bottom plate and the hot water chamber would be used to compensate
for inequalities in the glass and would rest upon the plates to be coated instead of the
lower side of the trough itself.
The Invention further relates to the means of supporting and guiding the plates
whilst, and after, being coated, so as to avoid defects in the film due to local differ-
ences of temperature consequent on the contact with the under sides of the freshly-
coated plates of their carrier-rollers or other supports.
It also relates to means of receiving waste emulsion from the plates, so as to avoid
the soiling of the under face of the plates with emulsion.
For this purpose, the plates are supported at their extreme edges only, by knife-
edged rails and run between guiding rollers or pins mounted alongside the knife-
edged rails, the edges of the plates overhanging gutters formed to receive superfluous
emulsion the guttered rails being arranged above a hot water tank by which an even
temperature is maintained.
Dated this 7th T1000

page_text: COMPLETE SPECIFICATION.
Improved Apparatus for Coating Photographic Plates.
We FRANK. BISHOP, of the firm of Marion and Company, of-22 and 23. Soho
Square in the County of Middlesex, Dealers in Photographic Materials and
ALEXANDER COWAN, of Chase Side, Southgate in the County of Middlesex, Manager
of Marion's Photo-Works, Southgate do hereby declare the nature of this invention
and in what manner the same is to be perforined, to be particularly described and
ascertained in and by the following statement :-
This Invention relates to improved apparatus for coating, photographic plates with
sensitive emulsion; and it has reference, first, to the coating trough whereby the
emulsion is deposited upon the plates, and, secondly, to the means of supporting and
guiding the plates and of preventing the soiling of the under faces in the operation
of coating. The improvements under the first head have for their object to ensure.
the uniform distribution of the emulsion and to enable the thickness of the deposit
to be easily regulated, and this object is attained by constructing and mounting the
trough in the manner hereinafter described. The improvements under the second
head have for their object to avoid the occurrence (except at the extreme ends of the
plate where they are of little consequence) of defects in the film due to local differ-
ences of temperature consequent on the contact of carrier rollers or other supports with
the under faces of the freshly-coated plates at points intermediate of their length. This
is accomplished by supporting the plates at their extreme ends only upon knife-edged
rails and guiding them between pins or rollers the said edges of the plates projecting
over gutters outside the rails in which superfluous emulsion is received.
Reference is to be had to the accompanying drawings, forming part of this
specification, wherein figure 1 is a perspective view of as much of a coating table
as is necessary to illustrate the invention. Figure 2 is a front elevation of part of
the coating trough, shewing one of the plate supports in cross-section. Figure 3 is
a cross-section of the coating trough. Figure 4 is a similar view, shewing the trough
provided with a flexible lip; and figure 5 shews one of the balance levers on which
the trough is mounted. Similar letters of reference indicate like parts in all the
figures.
The coating trough, which is of the ordinary. V-form in cross-section, has its
upright side, a and inclined side b constructed of strips of plate glass the inclined side b
being beddéd upon a hot-water chamber c and the other being fixed in position
adjustably with regard to the strip b so that its lower edge shall be at such a distance
from the surface of the strip 6, as to allow the emulsion to escape at a regulated rate
and to flow in a uniform stream down to the lower edge of the inclined strip b
The ends. of the trough are closed by blocks d which assist to maintain the proper
relative position of the strips a b. For this purpose circular end frames e are fixed
to the hot water chamber and carry binding screws fg, of which the former bear on
the top of the blocks d, which in turn hold the plate b to its bed, whilst the latter
serve through the medium of pressing blocks to hold the strip a against the upright
faces. of the end blocks d. The correct relative position of the plates ab is further
maintained throughout their entire length by set screws carried by intermediate
clamps i fixed to the back of the hot-water chamber, the screws j. pressing the.
plate to its bed and the opposite. pairs of screws k holding the strip a firmly in
position. The effective length of the trough may be adjusted. to suit the plates by
inserting filling blocks z alongside the end blocks'd, as shewn in figure. 1.. It will be
understood that all the metallic clamps, screws, and other fittings, likely to come
in contact with the sensitive emulsion, would be made of silver, the end blocks d being
preferably, made of wood. The hot water chamber c extends across the table and is
supported by ledges, at its ends. being seated in grooves in balanced levers m
mounted on pivots n at the sides of the coating table, the trough being so far counter-
balanced that the lower edge of the side b will rest lightly on the plates p to be
coated as they are carried beneath it and adapt itself to the varying thickness of the

page_text: plates. The chamber cis connected with flexible inlet and outlet pipes o o' at the ends
for maintaining a constant temperature by circulation of water. For coating large
plates, the trough would have a flexible lip along the lower edge of the strip b, to
compensate for the inequalities of the glass, said lip, which is shown in figure 4, being
formed of a strip of india rubber q interposed between the water chamber and the glass
strip 6 for which it forms a bed and beyond the edge of which it projects so as to rest
lightly on the plates being coated.
The plates p are fed to the coating table by endless carrying cords, or by any other
known means, and are received on knife-edged rails r formed on bars s, supported on
cross-bearers t over a hot water tank u the gauge of the rails being adjustable to suit
the dimensions of the plates p. Guide rollers v are mounted on the bars & so as to bear
against the edges of the plates at such intervals apart that the plates shall always be
guided by at least two rollers at each side. The edges of the plates project just over
gutters to in which superfluous emulsion flowing off the edges of the plates is received
and allowed to run off through holes in bars & into the tank. The plates p fed in
behind the trough are pushed forward under the latter, the plates abutting together
edge to edge in a continuous file, guided by the rollers v. In passing under the trough
they receive their coating which is kept at the proper temperature whilst the plates
are being conveyed to the cooling table.
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. The construction of the coating trough with its inclined and vertical sides
relatively adjustable, substantially as specified, for regulating the rate of flow of the
emulsion.
2. The combination, with a coating trough, of a hot water chamber for maintaining
the temperature of the emulsion constant, as described.
3. The construction of a coating trough of a pair of relatively-adjustable strips, of
which one is inclined, in combination with a hot water chamber having an inclined
side upon which the inclined side of the trough is bedded, as described.
4. The construction of a coating trough of a pair of relatively-adjustable strips of
glass, of which one is inclined, in combination with a hot water chamber having an
inclined side upon which the inclined side of the trough is bedded and with end
blocks and clamps whereby the strips are held in proper relative position, as
specified.
5. In a coating trough constructed as herein specified, the combination, with the
delivery side of the trough, of a lip of flexible material for depositing the emulsion on
the plates, as described.
6. Mounting the coating trough to oscillate on centres and counterbalancing it so
that the delivery edge of the trough shall bear lightly on the plates and adapt itself to
plates of different thickness, as described.
7. In a photographic-plate coating table, constructing the supports for the plates of
pairs of knife edged rails, in combination with lateral guide pins or rollers so arranged
that the plate will be supported and guided at its extreme edges only, whilst permitting
superfluous emulsion to overflow without soiling the under face of the plates, as
described.
Dated this 94th day of March 1890