Logarithmic primary testing system for security validation

Details Logarithmic primary testing system for security validation Logarithmic primary testing system for security validation

1980-05-23

1982-10-05

Punter, William H.

Optics: measuring and testing

Document pattern analysis or verification

250214R, 250556, 330110, G06K 982, H01J 4014, G01N 924, G01N 2117

Patent

active

043525598

ABSTRACT:
Apparatus for performing tests for determining the validity of a paper purported to be a valid instrument is presented. Fundamentally, the invention comprises a tray for receiving a paper offered as a valid instrument and maintaining the same in sliding relationship between a light source and reticle. A photocell is operatively connected to the reticle and senses light passing from the light source and through the paper and reticle. The output of the photocell is applied to an operational amplifier having a dynamic feedback network and the output of this amplifier is characteristic of both a grid pattern upon the paper and the optical density thereof. This output is then passed to an amplifier circuit which establishes an optical density domain and is operative to pass a signal only if the paper falls within such domain. This output is then passed to appropriate integrating and comparator circuitry to ultimately determine the validity of the paper.

REFERENCES:
patent: 3374361 (1968-03-01), Callis
patent: 3457421 (1969-07-01), Bayha
patent: 3999060 (1976-12-01), Skagerlund
Graeme et al., (Editors), "Operational Amplifiers Design & Applications", McGraw-Hill Book Co., 1971, pp. 236-268.

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