GB1371254A - Coded card - Google Patents

Abstract

1371254 Laminated coded card INTERNATIONAL BUSINESS MACHINES CORP 14 Nov 1972 [28 Dec 1971] 52479/71 Heading B5N [Also in Division B6] A coded card exhibiting a substantially uniform transmissivity and surface reflectance in the visible light region comprises a film (i) having laminated thereon a film (ii), which is selectively apertured or constitutes discrete portions, the films having different optical absorption characteristics at a substantially single frequency lying within an optical bandpass in the non-visible region, e.g. the infra-red. The films (i) and (ii) may be polyvinyl chloride and vinyl chloride-vinyl acetate copolymer respectively (bandpass at 3À5-7À0 microns; CO group absorption at 5À8 microns), film (ii) being applied to film (i) either by laminating under pressure at 250‹ C. for up to 1 second (to minimize plastic flow or by evaporation on to selected areas, and being protected if necessary by vacuum lamination thereon of a further polyvinyl chloride layer. The films (i) and (ii) may alternatively be of the same material but have different concentrations of CO group absorber due, e.g. to the presence of plasticizers and stabilizers. A further specified combination is polyethylene terephthalate/polyethylene, and other suitable materials for (i) and (ii) are listed.