ERASABLE AND REWRITABLE PAPER, PRINTING INK AND PRINTING APPARATUS AND ERASING APPARATUS USING THEM

摘要

PURPOSE:To obtain erasable and rewritable paper capable of being reused simply by forming the paper from a material reversibly changed to a non-visible state and a visible state so as to make a printed character or figure erasable and rewritable. CONSTITUTION:At the time of printing, sheets of paper 100 are taken out one by one to be inserted in a printing mechanism part and, when the set paper 110a is moved on a lambda theta lens 11 at constant speed, the laser beam emitted from helium-neon laser 7 is condensed by a condensing lens 8 and bent by 90 deg. to be incident to an optical modulation element 10 and laser beam is emitted by an ON/OFF signal and only the spot thereof develops a color to carry out printing. When paper 110b desired to be erased is inserted in an erasing apparatus, the image of said paper is read by an image scanner 19 to be recorded by a recorder 23 and, when the paper is moved to the lambda theta lens 20, the laser beam emitted from argon laser 25 passes through a condensing lens 26 to be bent by 90 deg. and passes through the lambda theta lens 20 to be emitted vertically to change to the original colorless characteristics. As a result, paper can be utilized many times.