| 摘要 |
PURPOSE:To enable secret papers prepared by using an electrophotographic copy machine and a black insulating paper containing no substance generating heat by absorption of light to be again judged, by a method wherein the preparation of a heat sensitive perforated plate is processed by using as a copy a reproduction obtained in a process that a black toner image corresponding to an original image is formed on a black insulating paper which does not contain substance generating heat by absorbing light, and a master is prepared on a heat sensitive perforated plate printing paper. CONSTITUTION:A black paper which is colored by a black coloring agent as a dye, or otherwise by a combination of pigments which do not generate heat by absorbing light is used. An image is copied by an first setting an original on an original-placing table, and a black toner image corresponding to an original image is formed on a black insulating paper. The image information part of an obtained copy becomes difficult to be interpreted. When a heat sensitive perforated plate is formed by taking this all black copy as an original, only an image part formed by a toner containing carbon is perforated, and a master corresponding to the original copy image is formed. When printing is carried out by using this master, only the perforated part is colored, and the original image is reproduced.
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