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US 4,588,298 AGranted
Step tablet
AssigneeFuji Photo Film Co., Ltd.
InventorMasao Nakamura
Life of this patent
Estimating the term…
Abstract
A step tablet with which an amount of exposure or degree of exhaustion of a developing solution can very readily been determined. The step chart is composed of a number of rectangular patches of photosensitive material, arranged in an order of sensitivity. The steps are each marked with two indicia, one having an optical density corresponding, upon development, of a step of minimum optical density, while the other corresponds to a step of maximum optical density.
Claims5
A step tablet comprising:
- a plurality of step areas, each of said step areas having a different optical density, and said step areas being arranged in an order of optical density;
- and first and second sets of marking indicia, one indicium from said first set of marking indicia and one indicium from said second set of marking indicia located within each of said step areas, said first and second sets of marking indicia having different optical densities wherein indicia of said first set of marking indicia have an optical density at the maximum corresponding to a step area of said step tablet of minimum optical density, and indicia of said second set of marking indicia have an optical density at the minimum corresponding to a step area of said step tablet having a maximum optical density, each of said first and second sets of marking indicia comprising indicia of the same type within each set.
Dependencies are inferred from the claim text.