вход по аккаунту


Патент USA US2566669

код для вставки
Patented Sept. 4, 1951
Reginald Geoffrey Horner, Ilford, England, as
- signor to Ilford Limited, ‘Ilford, England, a
British company
Application January 2, 1948, Serial No. 365
In Great Britain January 9, 1947
6 Claims. (C1. 95-2)
This invention relates to photography and par
ticularly to processes of photography which in
clude a step involving exposure to light or other
radiation of one side only of a photographic
material sensitive to such radiation.
Various processes of colour photography have
been described in which it is necessary to give
a general overall exposure to one side only of
There are innumerable variations possible in
the processing technique in which lights of col- ’
ours other than blue or radiation other than
light, e. g. ultra-violet or infra-red rays, are
usedfappropriate barrier layers being provided.
The practical aspects of the re-exposure step
are, however, somewhat di?icult. It is found
that there is a tendency for the re-exposure to
be uneven, especially if the photographic mate
is still wet from previous processing steps.
that none of the exposing light penetrates to the 10 rial
may be overcome by effecting the re-expo
other side of the material. The direct penetra
sure with the photographic'material immersed
tion of the exposing light through the ?lm is
in, water (or other inert liquid). Conveniently
usually prevented by the provision of a so-called
this may be done by arranging that the ?lm
“barrier" layer in the material, this layer ab
passes through a tank of water close to a glass
sorbing light of the wavelengths used for the
window in the side, bottom or top of the tank.
exposure. For example, a typical colour ‘photo
It has been found, however, that using this
graphic material may consist of the following
technique there is a considerable dif?culty ‘in
layers in order:
‘preventing any of the exposure light from pass
the photographic material under conditions Such
(a) A transparent support layer
ing the edges of the ?lm and being re?ected
(12) A red-sensitive silver halide emulsion layer
(0) A green-sensitive silver halide emulsion
back on to the surface which it is not intended
to expose. The di?iculty cannot be entirely
overcome by using a tank with walls of low re-i
(d) A yellow ?lter layer
(e) A blue-sensitive silver halide emulsion layer.
On exposure of such a material in a camera,
with layer e nearest to the lens, blue, green and
red records of the subject ‘photographed are pro
duced in layers e, c and b respectively. On de
velopment these are obtained as negative rec
ords. If now the individual layers e, c and b are
selectively re-exposed to render the residual sil
ver halide developable and are then selectively
?ecting power for, although special designs for
absorbing the light, such as multiple re?ection
by black glass mirrors, are possible, the water it
self scatters the light back, especially if it‘con
tai'ns dust particles or other suspended matter.
Nor isv it su?icient to arrange for the edge of the
?lm to run in a channel groove and so prevent
direct light entering the tank, since the inside
surfaces of the channel themselves tend 'to re
flect the exposing light.
According to the present invention a method
developed under conditions which yield in layer
exposing one side only of a radiation-sensi
e a yellow dyestu?, in layer 0 a magenta dye 35 tive material comprises directing radiation to
stuif and in layer 1) a cyan dyestuff, the dye
which the material is sensitive on to one side only
stuiis being formed in situ with the developed
of the material while the material is immersed
silver images, there is obtained, after removal of
in a liquid which absorbs the radiation em
the silver and residual silver salts, a positive
ployed, the material being positioned so that the
colour record of the original subject photo
depth of liquid between the source of the radia
graphed. In order to render the residual silver
tion and. the material is small compared with
halide in layer e developable, it may be re-ex
the depth of liquid in any direction behind the
posed to blue light. This light must not, how
material. The exposing radiation is therefore
ever, penerate to layers 0 and b and its penetra
much absorbed by the liquid before I'BaCh!
tion may be prevented by arranging that there 45
in the material, but stray radiation passing the
is a deep yellow ?lter between layers 0 and e.
edges of the material is su?iciently absorbed to
Similarly, if there is a deep yellow ?lter between
back scattering within the liquid to neg
layers b and 0, layer b may be re-exposed to
ligible proportions, and completely absorbed be
blue light (entering through layer a without af
50 foreit .can reach, the back pf the material after.
fecting layers 0 and e).
re?ection from any part of the walls of the tank
lying behind the plane of the material.
Preferably the liquid is contained in a tank
provided with a window in the side, top or bot
The invention is illustrated by the accompanya
lng drawing which shows exposing rays from a
source entering the transparent window of a tank
wholly ?lled with dyed liquid absorbtive of the
tom, the material being arranged to be close to
the window and being exposed by radiation en
tering through the window. If the window is at
the top of the tank, the liquid should preferably
exposing rays. A very short distance below the
window is the ?lm to be exposed, and as shown
the rays penetrate the ?lm as far as the ?lter
layer. The drawing shows the track of one ex
posing ray which passes the edge of the ?lm and
wholly ?ll the tank so that there is not a free
liquid surface between the source of radiation 10 is progressively absorbed by the “dyed liquid. It
and the material. It, this way unevennessv of
, shown as, re?ected from the wall‘rand bottom
exposure due to ripples on the surface of the
liquid may be avoided.
of the tank back to the underside of the ?lm, and
the relative intensity of the rays striking the
u The invention is of especial value in the ree
exposure of reversal type colour ?lm where’ it is"
film from, the topand those striking the ?lm from
16 below, ignoring light losses by reflection at the
required to re-expose a layer nearer to the ex
surfaces of the tank, will be inversely as the rela
posing source without a?ecting a layermoreigre-x
mote from the exposing source. Generally such
tive lengths of the ‘free paths of the rays from
the window ;to theltop of the ?lm and from the
re-exposure is made by means of blue light and
window to the bottom of the ?lm. On the dimen
in such a case the liquid may be water contain 20 sions of the drawing this will be about 100 to 1.
ing a blue-absorbing (i. e. yellow) dues'tuff. If
What I claim is:
the exposing source is white light or coloured
light other than blue, or ultra-violet or infra;
red rays, the liquid should be appropriately ab
sorptive'of such radiation;
1. In the development to colour of reversal type
multilayer colour ?lm wherein it is required to
re-expose an incident light-sensitive layer with
It is preferred that theliquidshould be con
tained in a vessel of which the internal walls
are also absorptive of ‘the radiation to be used
layer byv a?lter layer that is highly absorptive
for the exposure, and for most-purposes an inter
nally blackened tank is suitable.
of said incident radiation, the‘ method of pre-_
so venting re-exposure radiation that passes the"
edge of the filth from fogging" saidlsecon'd, more
The following speci?c example illustrates the
A‘_ photographic
out‘aifecting a SecondLmoreremQte, layerthat
iswalso sensitive to, the incident radiation, and
which ‘is separated from said, ?rst-‘mentioned
remote, layer by directing exposing radiation on
said incident‘ layer while‘ the ?lm is immersed
inhatycoloured ‘liquid ‘containing a dye that is
highly absorptive'of the“ radiation employed, the
film” being pqsitioned so that the depth of the
consisting ofa‘ transparent _
support bearing on one side two superimposed
sliver halide, photographic emulsions each sensi
tive to blue light and between them a deep yellow
coloured liquid between the source of radiation,
and the?lm is ‘small compared with the depth
?lter layer was suspended me tank of water inv
of liquid in'any, directionbehind the film.
a position parallel‘ to and about’ half an inch
from a glass window in the side‘ of" the tank. The 40 2.v In a: method of exposing one'incidentjight;
sensitive layer of‘ a’ photographic element’ having
tank was internally blackened'and measured 16
inches long by 12 inches wide by 37 inches deep.
at least one other differentiallylight-sensitive
layer that is separated from said ?rst-menl
tioned layer by a“ ?lter layer that‘ is highly ab
The window was in the smaller side so that a
depth‘ of 15% inches‘ofwater wasprovided behind
the ?lm. , For thegpurposes' of this example the
width‘ of the ?lm was about half the width of‘ the
window so that‘ avery considerable amount of
- fecting said other d’i?ereiit‘iall‘y light-sensitive
layer by directing light‘ radiations to one sur
theex'po'sing light'pa'ss'edby the edges of the film
eta into the tank. B1146 exposing light was used
aii'd‘the extent of the" exposure adjusted to about
20' times that necessary to render fully develop
ofwsu?icient density‘to prevent any direct expo
face of the incident layer, :while said photo
graphic element is‘ ifr'niners'ediin, a coloured liquid,
edntaiiling a, dye that is highly absorptive of
able the snterhende‘ef the emulsion nearer to
the exposing source. The yellow ?lter layer was
sure of the silver halide of the other‘: emulsion
ser'ptiveer the incident‘ radiation, the step of’
preventing the incident radiation that passes’
the edge of the photographic element from af
the’ light radiations, employed, the photographic
liqiiid tetweeplhesetreeer radiation and the}
incidentlayeris small tempered with the depth;
of liq-iii, any'direction behind the photograph;
element being positioned‘ so that the depth of,‘
layer, but nevertheless a dye image density of 1.3
was obtained in this layer owing to the exposure
received byback-re?ected light.
according to claim 2 wherein the‘
The addition to the water in the tank of a
liquid si's'y‘cont
rained in a vessel the ‘ internal walls
small amount of the dyestuff Tartrazine (Colour 60 of which-“are
also absorptive of said radiation.
Index No. 640) in the proportion of 2 parts in
sheiuil‘nmlethod? according tozclaimh 2 wherein
1 million parts of water by weight'was su?icient
to eliminate completely this back-exposure.
In practice about % of the above exposure to
blue light would be given, and precautions taken
to‘mask' the window down ‘to the size of the ?lm
would reduce the amount of exposing light pass
ing the edges of the ?lm by at least 10 times.
A“ concentration of Tartrazine of 2 parts in av
million would therefore give a factor of safety of
at‘ least 100, and a much smaller quantity of dye
would be su?icient to‘ prevent the fogging of the
second emulsion‘ layer, 1e. g. l'part‘of dye in'10'
million parts of water.
there is nohivree‘ surface ofliguid ‘between the
source of radiation and‘ the radiation-sensitive
.5- .111 amethod. of exposing: one incident light
sensitivelayer of a photographic ?lm element
having three/ differentially light-sensitive silver
halide layers and a blue‘, lighteabsorbing ?lter,
layer disposed: between‘ the‘ incident, layer and
the adjacentv light-sensitive layer,‘ the step’ of
preventing the‘ incident radiation ,that passes
the edge ofthe'?ln'i element‘ from‘ affecting‘ other
than said incident light-sensitive- layer by di-J
recting light radiations to one surface of the in
cident layer while said ?lm element is immersed‘
in a coloured liquid containing a dye that is
highly absorptive of the light radiations em
ployed, the film element being positioned so that
the depth of liquid between the source of radia
tion and the incident layer is small compared
with the depth of liquid in any direction behind
the ?lm element.
6. A method as set forth in claim 5 wherein
blue light radiations are directed to the incident 10
layer and the ?lm element is immersed in a yel
low-coloured liquid.
The following references are of record in the
?le of this patent:
Spiro ____________ __ Aug‘. 20, 1889
Spiro ____________ -_ Sept. 30, 1890
Eggert et a1. ________ Dec. 29, 1936
Eggert et a1. ______.._ Feb. 18. 1941
Bennes __________ __ Oct. 5, 1943
Seymour ________ __ June 10, 1930
Без категории
Размер файла
377 Кб
Пожаловаться на содержимое документа