Abstract Compensation apparatus includes a light source for illuminating an information code field disposed on microfilm having bit positions of selectively different relative optical densities (viz, transparent or opaque), and code field reading photocells responsive to the intensity of light passing through such bit positions to produce signals having levels representative of the relative optical densities of the bit positions in such code field, respectively. The level of the optical density signals will vary as a function of changes in the film density. The apparatus further includes circuitry responsive to the intensity of light passing through transparent bit positions for producing a reference signal which is a function of film density and the intensity of illumination of the light source, and a signal level comparator responsive to the ''''variable'''' optical density signals and the reference signal to produce digital signals representative of the relative ''''low'''' or ''''high'''' optical density of the bit positions and which are compensated for or free from ambiguity caused by variations in film density.
Inventors
👤 Richard D Stearns
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-26 21:18
CPC Classifications
G; G06; G06K; G06K17/00; G06K17/0016; G06K17/0019
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
244 words
In automatic retrieval apparatus including a code field reading station, means for moving an information bearing medium having at least one image and an identification code field disposed adjacent thereto to position such code field in said reading station, the code field having a plurality of information bit positions having relatively low (i.e., transparent) and/or high (i.e., opaque) optical densities respectively, and a light source for illuminating the code field, the improvement comprising: a. a plurality of photocells disposed relative said reading station and arranged so as to correspond to bit positions of a code field positioned in said station, respectively, said plurality of photocells being responsive to light from said source for producing signals having relative levels indicative of the relative optical densities of corresponding bit positions, respectively; b. automatic light control circuitry having (i) anothEr photocell disposed relative to said reading station and arranged to produce a signal corresponding to the intensity of light passing through low optical density bit positions of the code field; and (ii) memory storage means responsive to the signal produced by said another photocell for producing a reference signal; c. means responsive to said reference signal and said plurality of optical density indicating signals for producing digital signals representative of the relatively low or high contrast of said bit positions, respectively; and d. logic and control means responsive to said digital signals for determining when a code field having a desired information is at said reading station.
Claim 2
Dependent Claim
244 words
In automatic retrieval apparatus including a code field reading station, means for moving an information bearing medium having at least one image and an identification code field disposed adjacent thereto to position such code field in said reading station, the code field having a plurality of information bit positions having relatively low (i.e., transparent) and/or high (i.e., opaque) optical densities respectively, and a light source for illuminating the code field, the improvement comprising: a. a plurality of photocells disposed relative said reading station and arranged so as to correspond to bit positions of a code field positioned in said station, respectively, said plurality of photocells being responsive to light from said source for producing signals having relative levels indicative of the relative optical densities of corresponding bit positions, respectively; b. automatic light control circuitry having (i) anothEr photocell disposed relative to said reading station and arranged to produce a signal corresponding to the intensity of light passing through low optical density bit positions of the code field; and (ii) memory storage means responsive to the signal produced by said another photocell for producing a reference signal; c. means responsive to said reference signal and said plurality of optical density indicating signals for producing digital signals representative of the relatively low or high contrast of said bit positions, respectively; and d. logic and control means responsive to said digital signals for determining when a code field having a desired information is at said reading station.
Claim 3
Dependent Claim
28 words
The invention as set forth in claim 1 wherein said bit positions have alternate optical densities and wherein the width of such bit positions defines its information content.