Registers – Coded record sensors – Particular sensor structure
Patent
1979-02-13
1980-05-27
Cook, Daryl W.
Registers
Coded record sensors
Particular sensor structure
235487, 365124, G06K 712, G06K 1906
Patent
active
042046386
ABSTRACT:
A process for coding a set of access cards adapted to control an apparatus for opening, locking or releasing a processing device and for the ultimate determination of the validity of a card when it is presented in the apparatus, the coding being effected by the formation on the cards of at least one diffraction grating whose recognition is effected by projection of a luminous beam on the grating and analysis of the diffracted beams. The grating is formed by means of a machine having a kinematic drive which is intentionally irregularized to produce at least one deviation in the spacing of the lines of the grating which varies periodically with a determined period and maximum amplitude. The modified grating will produce a supplementary satellite diffraction beam when illuminated by the luminous beam and whose angular position and intensity is measured to establish the validity of the grating.
REFERENCES:
patent: 3312955 (1967-04-01), Lamberts et al.
patent: 4011435 (1977-03-01), Phelps et al.
patent: 4023010 (1977-05-01), Horst et al.
patent: 4072098 (1978-02-01), Granzow
patent: 4143810 (1979-03-01), Greenway
Cook Daryl W.
Instruments S.A.
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