Photocopying – Projection printing and copying cameras – Illumination systems or details
Patent
1975-09-04
1977-04-12
Adams, Jr., Russell E.
Photocopying
Projection printing and copying cameras
Illumination systems or details
355 38, 356222, 354 31, G03B 2774, G03B 2778
Patent
active
040171795
ABSTRACT:
An automatic density control device for photographic printers for sensing and correcting for a "subject failure" in a photographic negative, where the subject area of the negative is out of the optimum density ratio to the background area, which device includes a frusto-pyramidal radiation directing member having its enlarged end proximate to the negative and its small end remote therefrom and being positioned to receive the radiation from a source through the negative and having subject sensing means mounted at the central portion of the enlarged proximate end of said member to sense the radiation passing through the central subject area of the negative and also having background sensing means mounted at the diminished remote end to sense the radiation passing through the marginal portions of the negative and the marginal portions of the enlarged end of said member and including circuitry for comparing the signals produced by said subject sensing means and background sensing means and thus deriving a density signal which is used to control the exposure time during the printing process.
REFERENCES:
patent: 3694074 (1972-09-01), Huboi et al.
patent: 3768903 (1973-10-01), Steinberger et al.
patent: 3790275 (1974-02-01), Huboi et al.
patent: 3855601 (1974-12-01), Uchiyama et al.
Gilligan Patrick J.
Harvey Ronald B.
Jensen Gerald A.
Pone, Jr. John
Schrupp Kenneth B.
Adams John W.
Adams, Jr. Russell E.
Pako Corporation
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