Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/52—Compositions containing diazo compounds as photosensitive substances
  • G03C1/62—Metal compounds reducible to metal

Definitions

• This invention relates to a method of producing photographic contrasts and more particularly to material sensitisedby means of a photosensitive diazonium compound. It is particular- 1y important for producing copies of sound-pluspicture films since it enables contrasts of difierent graduation to -be obtained side by side on one and the same material.
• This graduation may be decreased by variation of the composition off the liquid by means of which the photographic material is sensitised, or of the developer, but more particularly by variation of the time of development. If, however, itis desired thus to obtain a gamma value of about 2 or lower as is desired; for-example, for
• thes aid" means of reducingthegamma arenot very appropriatefor obtaining contrasts of different graduationsside by'side on one and the same piece of material-I Even if the graduation of'a copy is reduced by placing a line grate during'copying between the image negative to be copie'dand the copying material (cf; French patent specification 848,531), then in many cases there: arises the difiiculty that suificiently great'reductionof the gamma is obtained at theexpenseof themaximum black-- ening. Furthermore, this method of reducing the gamma has the disadvantage that the copies obtained'exhibit a grate structure and this may lead to annoyances, such as granular structure; in projectingthe copy.
• An inner grate is obtained by providing in the photographic material local'variations' in the concentration of the photo-sensitive substance'by in"- cluding in the materiala substance dispersed'colloidally (cf. French patent specification 8413911).
• the present invention relates to an entirely new method of gamma control by which it is possible, if" desired in conjunction with other methods oiinfluencing the gamma, to obtain control of the gamma value within very broad limits While retaining sufficient maximum blackening and'avoiding grate structure.
• the gradation is controlled by adjustment of the moisture content'of thematerial at the moment of the exposure;
• the method according to the invention underlies the idea of preparing photographic material in which upon exposure, in addition to the reaction leading to the final photographic contrast,
• the means of suppressing or facilitating one of the reactions consists in adjusting the moisture content.
• a very important advantage of the invention is that it enables contrasts of different graduations to be produced side by side on one and the same material by providing for the exposure required for the obtainment of contrasts of difierent graduation, to be effected at different states of humidity of the photo-sensitive material. Consequently, the invention is very important for producing copies of sound films, which exhibit images and sound recordings on one and the same film and which require different gradations for picture and sound.
• photographic material consisting of a transparent carrier, for example of regenerated cellulose, treated with a photo-sensitive diazonium compound and mercurous salt, which material is developed physically subsequent to the exposure, it is possible, for example, to produce copies of sound film having an image of low gamma value and a sound recording of high gamma value.
• the picture strip and the sound record are copied in different states of humidity of the material.
• the development of the exposed copy is preferably effected in one process. Copies thus obtained are inexpensive and of excellent quality.
• the invention further permits of obtaining, in the case of a picture film, difierent gradations for successive series of images. It is possible, for example, with successive scenes to obtain the gradation which is most desirable for each scene by providing for a suitable state of humidity in copying.
• a further application of the possibility of providing different gradations on one and the same material is, in the case of one image, to give different gradations to different portions.
• the background and the air respectively may b given different gradations.
• the relationship between the moisture content of the photographic material and the gamma value obtained is dependent on various factors such as the nature of the carrier, the quantity of the photo-sensitive compound in the carrier, etc. This may, however, be determined empirically.
• a reproducible adjustment of the moisture content is of great importance.
• a very reliable adjustment of the moisture content is obtained by bringing the material into a state of equilibrium with an atmosphere of appropriate humidity, which may be effected by leaving a film of regenerated cellulose, for example, for 24 hours in such an atmosphere.
• the material it is, however, not necessary that the material be in a state of equilibrium with respect to its moisture content. It suffices if in the zone of the material in which the photochemical conversion takes place, the moisture content attains the value required in view of the desired gradation. This allows appreciably more rapid adjustment of the moisture content than if the attainment of a state of equilibrium is awaited. In many cases it will be desired to work, for example, with an increased moisture content, by which we mean a moisture content of the photo-chemically active part of the material which is greater than the moisture content which this part would have if it were in equilibrium with an atmosphere of a relative degree of humidity of 65% at 20 C.
• Treating in such a case the photo-sensitive material with water and subsequently drying to a small extent, or conversely introducing dry material into a moist atmosphere permits adjustment of the moisture content within a very short time to the increased value desired.
• the essential point is the moisture content which the material possesses at the moment of the exposure. It has been found that in this way a reliable and reproducible control of the gamma value is quite possible. The gamma value obtained is not dependent on variations in the moisture content after the exposure.
• a water absorbing layer for example of gelatine or an other albumin or albuminous product, in which the photo-sensitive compound is provided is' very suitable. It is alternatively possible to utilize materials wholly or'in'part consisting of polycond'ensation products capable of being swollen, such as polyamides.
• EXAMPLET Regenerated. cellulose was impregnatedwith a solution 0150.4 n. hydroxy-l, diazonium-2, methyl-6, benzene sulphonic acid-4, 0.-1 nmercurous nitrate and 0.2.n nitric acid..
• the photo-sensitive material thus. obtained. was. conditioned at 20. C..wi.th a relative.- degree. of humidity of 40% and, 90% respectively by leaving it. for, a considerable timein an atmosphereof. such humidity. and.temperature.-
• the material, in. this. state contained and. 28% by. weight of'water. Subsequently, the material was. exposed for. seconds behind a sensitometer. wedge by means of. a Philips superhighepressure.
• mercury lamp of 500 watts whichwas provided at a distance of 5.0 cms..from the photographic material. After the. exposure a portion of the material was developed ford minutes and another portion for 2 minutes at C. in-- a solution. consisting of 3% of metol (sulphate salt of p-methyl-aminophen01), 4% of tartaric. acid and 0.4% of silver nitrate.
• Regeneratedcellulose was impregnated with a solutionof 0.4 n hydroxy-l, diazonium-2, methyl- 6, benzene sulphonic acid-4, 0.1 nmercurous nitrate and 0.05 n nitric acid. After removal of the superficially adhering liquidv and drying to differing moisture. contents, exposure-.tookplace 7' for 6 seconds; under a: sensitometer: wedge: by means of; a Philips superhighepressure: mercury lamp of 500 watts, whichwas provided at: a dis-.- tance of 20 cms. fromithe.photo-sensitive material. Subsequently, devel'opment took place for 5 minutes at 20 C.
• EXAMPLE L 7 Table 4 shows the values found for the graduations. The moisture content of the film as shown has been found by drying.
• Regenerated cellulose was sensitised by impregnation with a solution consisting of 0.7% or diphenyldiazonium sulphate and 0.9% of silver nitrate, conditioned at 20 C. in an atmosphere of a relative degree of humidity of 40% and '75 respectively, and subsequently exposed for 3 -minutes under a sensitometer wedge by means of a Philips superhigh-pressure mercury lamp of 500 watts provided at a distance of 10 cms.
• Table 5 shows the gradients found as a function of the relative degree of humidity.
• a transparent cellulosic moisture absorbent carrier supporting a light-sensitive system containing a diazonium compound and a reducible mercurous salt the steps comprising varying the moisture content of a photographic record portion of said carrier to an extent at which the resultant moisture content of said photographic portion has a value of about 10 to 28% by weight of the carrier and corresponds to a state of equilibrium between said photographic portion and an atmosphere having a relative humidity of about 40 to 90%, varying the moisture content of a sound record portion of the carrier parallel to said film record portion to an extent at which the resultant moisture content of said sound portion has a Value different than the moisture content of said photographic portion and has a value of about 10 to 28% by weight of the carrier and corresponds to a state of equilibrium between said sound portion and an atmosphere having a relative humidity of about 40 to 90%, and exposing said photographic and sound portions containing the said amounts of moisture at the time of exposure to the action of light through a negative having a photographic record and a sound record with i

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=19750393

Family Applications (1)

Country Status (7)

Cited By (2)

Citations (16)

• 0
  • BE BE470580D patent/BE470580A/xx unknown
  • NL NL66149D patent/NL66149C/xx active
• 1947
  • 1947-01-15 GB GB1362/47A patent/GB678911A/en not_active Expired
  • 1947-01-16 FR FR941053D patent/FR941053A/fr not_active Expired
  • 1947-01-16 CH CH263994D patent/CH263994A/de unknown
  • 1947-02-08 US US727310A patent/US2571671A/en not_active Expired - Lifetime
• 1948
  • 1948-11-05 DE DEP20788D patent/DE854886C/de not_active Expired

Patent Citations (16)

Also Published As

Similar Documents