Abstract: A counterfeit-proof paper which discourages an attempt at reproduction of the print made thereon is disclosed. Since this paper has an apparently planar surface, the latent image contained therein escapes perception with unaided eyes. Once this paper is subjected to a copying action of a copying device, the latent image is made to appear clearly regardless of the type of copying device, the direction of scanning light, or the manner of placing the paper relative to the copying device. Specifically, either of a latent image and a background conferred upon the surface of a substratum paper is formed of mesh points of a 150-line 10% level and the remainder thereof is formed of concentric circular patterns. The thin lines forming the circles of the concentric circular patterns have a thickness of 1/10 mm and are spaced with an interval of about 1/2mm.

Abstract: A copy-proof sheet having a longitudinal axis, and being constituted by a background and at least one latent mark, at least one of the background and the latent mark being formed of multi-line images of about 65-line 10% which are reproducible on a copy obtained from the sheet, the other of the background and the latent mark being formed of fine mesh images of about 150-line 10% which are not reproducible on a copy obtained from the sheet; the background and latent mark being distinguishable on the obtained copy due to a difference in color tone; the multi-line images being made up of longitudinal line-containing and lateral line-containing square areas each having sides of about 3 mm long; each longitudinal line-containing square area being made up of lines oriented parallel to the longitudinal axis of the sheet, and each lateral line-containing square area being made up of lines oriented normal to the longitudinal axis; and the longitudinal line-containing and lateral line-containing squares being juxtapose

Abstract: There is provided a process for preparing a film positive sheet for a forging-by-copying-proof print in which a first background image sheet is placed on a first latent image sheet, an unexposed film having a photosensitive membrane on the undersurface is placed on the background sheet to provide a primary three-layer film structure, the three-layer film structure is illuminated to partially expose the film, the first latent image and background sheets are replaced by second latent image and second background sheets, respectively, to provide a secondary three-layer film structure, the secondary three-layer film structure is illuminated to completely expose the partially exposed film and the second latent image and background sheets are removed from the secondary three-layer structure to thereby provide a film positive sheet for a forging-by-copying-proof print. Then, a forging-by-copying-proof print is prepared from the film positive sheet by a printing method such as offset or relief printing.

Abstract: There is provided a process for preparing a film positive sheet for a forging-by-copying-proof print in which a first background image sheet is placed on a first latent image sheet, an unexposed film having a photosensitive membrane on the undersurface is placed on the background sheet to provide a primary three-layer film structure, the three-layer film structure is illuminated to partially expose the film, the first latent image and background sheets are replaced by second latent image and second background sheets, respectively, to provide a secondary three-layer film structure, the secondary three-layer film structure is illuminated to completely expose the partially exposed film and the second latent image and background sheets are removed from the secondary three-layer structure to thereby provide a film positive sheet for a forging-by-copying-proof print.