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Патент USA US2126516

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' Aug. 9, 1938;
G. sZAsz
Filed Sept.. 13, 1955
Patented Aug’. 9, 1938
rnoroonarmo rnocnss '
Géza Szasz, Berlin-lteinickendorf-Ost, Germany
Application September 13, 1935, ‘Serial No. 40,486
In Germany September 15, 1934
5 Claims. ‘(01. 9.5'-—'l)
This invention relates to improvements in or
relating to photographic processes and emulsions
emulsion prepared in the above manner has a
strong tendency towards reversal i. e. upon sub
for use therein and has for one of its objects to sequent exposure'the’ exposed portions tend to
provide an‘ emulsion or emulsion layer which . become bleached and this tendency can be en
hanced by adding to the light sensitive material 5
5 upon exposure and subsequent development en
ables a direct positive to be obtained in a, very or. to‘ the emulsion thereof suitable dyestuffs.
Thus for éxample I find that specially beneficial
simple and expeditious manner.
It is already known that by adopting‘ what results can be obtained by' using safranine, azine,
are known as'rev'ersing processes which usually oxazine,-thiazine, quinoxaline and similar dye
which possess desensitizing characteristics, 10
v10 involve exposing an emulsion up to a point of stuffs
although in some cases I also ?nd that the
solarization or maximum blackening, and subse
bleaching e?ect can be increased by employing
quent exposure for the actual taking of a pho
tograph, a direct positive copy may be obtained dyestuifs which have a sensitizing effect on'usua‘l
but known processes have not been successful in emulsions such for instance as thio-carbocya
nines. Moreover any means favourable towards 15
15 practice inter alia on account ‘of the very long _ the Herschel effect such for example as copper
exposure necessary and the unsatisfactory nature
salts can also be used with advantage for in-‘
‘of the'?nal copies. Further objects of the pres
ent invention are to provide a process which is creasing the bleaching eiiect.
The solarization of the silver halide may be
free from these objections to previously known‘
processes and to enable good quality direct copies _ effected at any desired stage or stages of the 20
‘manufacture of they emulsion, for- instance di
rectly after precipitation in which case'there is
the advantage that the bulk of the material is
small and the uniform treatment of each particle
by light 'is facilitated.
exposure-andthe "reverse" picture. being pro
to be made" very .quickly and in a manner ‘as
simple as that ordinarily followed in making a
negative copy of an original, the reversing ac
tion 1. e. the reduction of the darkening at the
duced during a single development. _
According ‘to one feature of the present inven
tion I provide a photographicemulsion having
30 the property of reversing'upon exposure char
way of example one embodiment of apparatus
which may be employed for carrying out the pre
liminary-exposure in cases wherein this method
of attaching solarization is ‘employed.
’ duced in a su?lciently small, amount ofrgelatine
Figure -1 is‘a diagrammatic side view of an
apparatus for carrying out the solarization step
‘ to prevent ‘the immediate formation of a stable
' Figure 2 is a diagrammatic end view thereof.
acterized in that the desired silver halide is pro
of this invention; and
emulsion‘ or. suspension but tends to become pre
In the drawing, I designates a tube through 35
which the emulsion is caused to flow, the speed
flow being regulated by a valve 2. This tube
ing process by. being allowed to stand for some ‘of
through‘ a box-like container. in which
time in the cold and the supernatant solution_ are located
a plurality of suitable light sources
may be removed. by ?ltration or decanting and ‘3. These light
sources are preferably electrical 40
the silver halide may then be emulsi?ed in a gela
ones and‘ means 4 are preferably provided for
tine solution vofthe desired concentration for in
controlling the voltage or degree of illumination
stance about 8% to 10% in which condition the and/or
the wave length of the light. Any de
solution can be poured.
sired ventilating valves such as those indicated
cipitated and settle on'the bottom ‘of the vessel.
If desired, the silver halide may undergo a matur
In some cases, and dependent upon the gra
45 dation required, the supernatant solution may
at 5 may of course be provided in the container.’ 45
It will be appreciated that by employing the
above apparatus it is ensured that thelmaterial
under .treatmentvis uniformly exposed on all
not be removed or ‘be only partially removed and
the silver halide emulsi?ed in the concentrated
gelatine layer' may be subjectedv to a watering
sides and that by controlling the rate ‘of flow as
well as the degree of illumination the treatment 50
‘The emulsion produced in the above manner
is subjected to a process resulting in solarization _ is kept under very line control. ‘If desired in -
for instance by being exposed in suitable appa
ratus and/or chemically by‘ the addition of suit
order to,permit of additional control or to im
' prove the characteristics of the treatment, light ,
able agents such for example as silver nitrate,
?lters may be employed in conjunction with the
sulphur“ compounds. dyestuffs or the like.
light sources.
An ,.
Whilst I have hereinbefore given some exam
at least a part of the supernatant liquid is sep
ples of methods of and apparatus for carrying ‘ arated from the precipitated silver halide prior
out the present invention it is to be understood to the emulsifying step.
v‘that the speci?c details may be varied or modi
3. The process as claimed in claim 1 in which
iied without departing from the scope thereof.
Thus for instance the light sensitive material
employed may be any suitable compound or
compounds of silver and halogen, such for exam
ple as a mixture of silver halides and the' process
10 may be used ior making'direct positive copies of
any originals such for example as- views or docu
ments or facsimile copies of positive or negative
documents or pictures.
I claim:
the silver halide is matured by standing in the 5
cold prior to the emulsifying step.
4. The process as claimed in claim 1 in which
said‘solarization step is performed at least in part
by exposing the silver halide to the action of light
while ?owing in a small stream.
5. The process of ‘manufacturing photographic
emulsion layers directly yielding positive pictures,
which comprises forming silver halide in a solu
tion containing an amount of gelatine so small
1. The process of manufacturing photographic
to prevent the formation of a stable-emulsion,
emulsion layers directly yielding positive pictures, \as
settling the silver halide from the solution, sep
which comprises forming silver halide in a solu
tion containing an amount of gelatine so small
arating at least a part of the supernatant liquid
from the precipitated silver halide, bringing the
as to prevent the formation of a stable emulsion, silver halide to a condition of solarization by
settling the silver halide from the solution, bring- ' exposing the same to the action of light while
ing the silverl‘halide to a condition of solariza
?owing in a small stream, and thereafter emul
tion, and thereafter emulsifying the silver halide
in a gelatine solution of a concentration such
that a stable emulsion capable of being poured
25 is obtained,
2. The process as claimed in claim 1 in which
sifying the silver halide in a gelatine solution
of a concentration such that a stable emulsion
capable of being poured is obtained.
Gaza szAsz.
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