Apparatus and method for altering the contrast characteristic of photosensitive materials

Claim 1

APPARATUS FOR ALTERNAING THE CONTRAST CHARACTERISTIC OF COMPARATIVELY HIGH CONTRAST PHOTOSENSITIVE MATERIAL IN A CONTROLLED AND ACCURATELY DUPLICATABLE MANNER, COMPRISING: AN ELECTROLUMINESCENT PANEL WHICH LUMINESCES INSTANTANEOUSLY AND UNIFORMLY TO A LUMINOUS LEVEL HAVING A FUNCTIONAL RELATIONSHIP WITH THE MAGNITUDE OF APPLIED VOLTAGE, SAID PANEL ADAPTED TO RECEIVE SHEETS OF PHOTOSENSITIVE MATERIAL IN OVERLYING RELATION; AN ELECTRIC POWER SOURCE ADAPTED TO BE CONNECTED TO SAID PANEL; A TIMING SWITCH MEANS IN CIRCUIT WITH SAID POWER SOURCE AND SAID PANEL, SAID TIMING SWITCH MEANS WHEN ACTUATED ESTABLISHING A FIXED PERIOD OF PANEL LUMINESCENCE; AND A VOLTAGE MAGNITUDE CONTROL MEANS IN CIRCUIT WITH SAID POWER SOURCE, SAID TIMING SWITCH MEANS AND SAID PANEL, SAID CONTROL MEANS EFFECTIVE TO VARY THE MAGNITUDE OF THE VOLTAGE APPLIED TO SAID PANEL IN A CONTINUOUS MANNER AND INCLUDING IN SERIES A VARIABLE RANGE RESISTANCE FOR COARSE ADJUSTMENT ADAPTED TO BE ADJUSTED IN ACCORDANCE WITH THE SPEED RANGE OF THE COMPARATIVELY HIGH CONTRAST PHOTOSENSITIVE MATERIAL FROM A PARTICULAR EMULSION BATCH AND A VARIABLE CONTRAST RESISTANCE FOR FINE ADJUSTMENT ADAPTED ON SECCESSIVELY DIFFERENT ADJUSTMENTS TO PROVIDE LIGHT LEVELS WHEREBY RESPECTIVE SHEETS OF PHOTOSENSITIVE MATERIAL FROM THE SAME EMULSION BATCH WHEN EXPOSED TO THE LUMINESCENCE FOR THE PERIOD PROVIDED BY SAID TIMING SWITCH MEANS ARE GIVEN ALTERED DIFFERENT CONTRAST CHARACTERISTICS, WHEREBY PRINTING OF OPTIMUM CONTRAST CHARACTERISTIC CAN BE ACCOMPLISHED WITH SHEETS OF COMPARATIVELY HIGH CONTRAST PHOTOSENSITIVE MATERIAL FROM DIFFERENT EMULSION BATCHES AND WITH NEGATIVES OF DIFFERENT DENSITY CHARACTERISTICS.