GB1229886A - - Google Patents

Abstract

1,229,886. Handwriting comparing; fraud preventing. CANON CAMERA CO. Inc. 11 June, 1968 [12 June, 1967 (2)], No. 27764/68. Headings B6A and B6X. [Also in Divisions C4, G2 and H2] A method of concealing and subsequently identifying designs or marks on a sheet 1 such as a check consists of making the mark with a material impermeable to infra-red rays and covering it with material opaque to visible light but permeable to infra-red and identifying the mark by exposing the sheet on one side to infra-red rays to generate a shadow of the mark which is recognized by viewing an ultra-violetirradiated fluorescent member upon which the infra-red image is cast. A design or mark is written with ink impermeable to infra-red, such as ink mainly composed of carbon black, and is smeared with ink opaque to visible light, for example ink mainly composed of oil black, and the surface of the sheet containing the signature is sealed with a thin film 3<SP>1</SP> having the same properties as the ink used for the smearing. A thin fluorescent plate 4, covered on one side with a layer of transparent acetate or polyester (40), Fig. 9 (not shown), or optical fibres (40<SP>1</SP>), Fig. 10 (not shown), is placed on top of the sheet with the fibre layer next to the sheet and an infra-red ray source 5 and a filter 6 passing only infra-red are placed behind the sheet 1 and when the source 5 is switched on an ultraviolet source 7 is switched on simultaneously to illuminate the fluorescent plate 4. The fluorescence is quenched by the action of the infra-red at all points of the plate except at those points corresponding to the mark which are shielded so that the concealed design becomes visible. The paper 1 is held between the filter plate 6 and fluorescent plate 4. The design 11 to be compared is placed on a base 10 and illuminated by a lamp 12 and a semi-reflecting mirror 9 is provided so that the design 11 and the design 4 may be viewed as if superposed by the eye at 13. In an alternative embodiment, Fig. 5, a design on a sheet 1 is inserted between the baseplate 15 and an infra-red filter and is irradiated from an infra-red source 5. The infra-red shadow of the design is formed on the fluorescent plate 4 and illuminated from the same side by an ultra-violet lamp 7 forming, as in the previous embodiment, an image of the design to be compared visually with the design 11 on the base 10 by means of a semi-reflecting mirror 9. Details of a machine for performing this operation and a quick lighting system for lamp 12 are also given.