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
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/49—Print-out and photodevelopable emulsions

Definitions

• This invention relates to a process for forming images in 'light-developable, direct-writing, radiation-sensitive elements, and more particularly to a dry process.
• Light-developable, direct-writing photographic materials have been developed for light writing and oscillo graphic recording purposes which does not require liquid processing such as chemical development. Such materials have many advantages in practical use as the inconvenience of liquid processing can be eliminated, and the image can be viewed at a mini-mum of elapsed time after recording.
• the direct-writing photographic element described in this application comprises a support, e.g., paper, coated with a colloid-silver halide emulsion having dispersed therethrough light-sensitive silver halide grains which preferably are in the range of from 0.1 to 10 microns in diameter and containing 0.5 to 120 mole percent or more, and preferably to 60 mole percent, of a stannous sa'lt, 0.1 to 20 or more, and preferably 0.5 to 5 mole percent, of a plumbous salt and an excess of bromide ions, all per mole of silver.
• a support e.g., paper
• a colloid-silver halide emulsion having dispersed therethrough light-sensitive silver halide grains which preferably are in the range of from 0.1 to 10 microns in diameter and containing 0.5 to 120 mole percent or more, and preferably to 60 mole percent, of a stannous sa'lt, 0.1 to 20 or more, and
• the above photographic element is usually exposed to radiation from a xenon tube and/or a high pressure mercury-arc lamp containing a high proportion of ultraviolet radiation for a period ranging from 0.1 to 10,000 microseconds or more. After exposure, the material is light-developed by exposure to daylight or low intensity incandescent or fluorescent light or by the use of photofiood lamps commonly used in photography.
• a further object is to provide such a process of producing images by light alone wherein the background density or fog and gamma can be ac curately controlled in a simple and easy manner. Still further objects will be apparent from the following description of the invention.
• the process of the present invention comprises:
• the pre-exposure can be of the same intensity as that used during photodevelopment of the latent image-bearing layer.
• the background density or fog is not reduced, but toe speed is reduced which provides a higher gamma. This, in turn, reduces flare or halation around the image edges thereby giving image records of improved sharpness.
• the pre-exposure is preferably of less intensity that that used for photodevelopment.
• the intensity of the pre-exposure radiation will range from 1 to of the intensity of the photodevelopment radiation.
• photodevelopment radiation intensity of 3800 metercandles was used.
• the pre-exposure was carried out using two l5-watt T-8 white fluorescent tubes and the intensity was varied by the use of neutral density filters.
• the latent image exposure was by means of a xenon tube discharge flash.
• Various exposures were made to obtain several points on the conventional sensitometric H&D curve. .Thcsc are expressed in terms of log E on the H&D exposure scale.
• Example I A gelatino-silver chlorobromide emulsion washed to remove most of the soluble salts from the mixing step and containing 1 mole percent of plumbous nitrate, 10 mole percent of stannous chloride and 64 mole percent excess bromide ions, all based on the silver halide, was
• the coated element was pre-exposed to two 15-watt T-8 white fluorescent tubes at an intensity of about 380 meter-candles for the tests reported in the following table.
• the latent image exposure was made by a xenon flash tube and is given in meter-candle seconds in said table.
• the element was then photodeveloped at an intensity of 3800 meter-candles for 5 minutes to give the reflection densities as shown in the table.
• Pre-exposure intensity 380 meter-candles Latent image flash precxposure times exposure, metercandle-seconds -0 seconds seconds seconds seconds UINN aomom 0. 0 U lit- M le ume:
• Pre-cxposure (lamina Image contrast, time, in seconds 30 Di; D'hnoo-Dlh;
• Example II Example II was repeated except that the pre-exposure was carried out using 38 meter-candles intensity instead of 380 meter-candles. The results are as follows:
• Example IV Example I was repeated except that the pre-exposure step was carried out at a light intensity of 1900 metercandles with the result shown in the following tables.
• Example V The emulsion of Example I was optically sensitized with 5,5-dimcthyl-3,3,9-triethylbenzosclenazole carbocyanine iodide.
• meter-eandlc-seconds seconds 60 seconds 120 seconds 0. 38 0. 33 0.32 0. 28 0. 43 0. 37 0. Bl 0. 28 0. 5i 0. 50 0. 38 O. 38 0. 58 0. 60 0. 55 0. 5;: 0. 02 0. 50 0. 62 0. 58
• Example VI Example V was repeated except that the pre-exposure step was carried out at 38 meter-candles intensity with the following results:
• preexposure of 1/100 the intensity of the photodevelopment light is not as effective as pre-exposure of 1/10 of the photodevelopment radiation intensity.
• the pre-exposure step of the present invention may be carried out continuously by passing the paper or film bearing the direct writing emulsion past an exposure station which may be a lamp or bank of lamps capable of provid ing a light flux of suitable intensity at a rate designed to give the desired exposure.
• an exposure station which may be a lamp or bank of lamps capable of provid ing a light flux of suitable intensity at a rate designed to give the desired exposure.
• the exposure may be applied by the manufacturer or the user, and in the latter case appropriate pro-exposure means may be incorporated as an intergal part of equipment for impressing a latent image which may also incorporate means for photodevelopmcnt with or without the use of added heat.
• the direct writing products treated according to the present invention exhibit increased image sharpness and usually lower fog. This is advantageous in line and office copy applications where maximum shaprness as resolving power is sought. For example, in copying line drawings, improved resolution obtainable with this process makes it possible to separate closely spaced lines, etc.
• the ability to adjust gamma by alteration of preexposure intensity and time makes is possible to obtain a variety of different contrast effects, i.e., variable gamma from a single emulsion.
• the reduction in fog is particularly desirable when using such materials in the preparation of proof-prints from portrait negatives, etc.
• the invention is especially advantageous where images are formed in optical oscillographs using low writing speeds.
• emulsion layer is a gelatino-silver halide emulsion layer.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

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Citations (2)

• 0
  • BE BE624802D patent/BE624802A/xx unknown
• 1961
  • 1961-11-16 US US152914A patent/US3241961A/en not_active Expired - Lifetime

Patent Citations (2)

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