FERROELECTRIC IMAGING - A PROPOSAL FOR FORMATION OF LONG-LIFE ELECTROSTATIC IMAGES

A novel imaging process based on the polarization reversal of a ferroe lectric polymer film (e.g. copolymer of vinylidene fluoride and tetraf luoroethylene) was proposed and the basic requirements for polarizatio n reversal were investigated by D-E hysteresis measurements and also b y time domain measurements of switching transients. It was found that the permissible temperature for successful image formation was 100 deg rees C. The decrease of the coercive field, however, was only 15 MV/m, apparently not large enough in the temperature range between 20 degre es C and 100 degrees C for practical application. However, when the fi lm was subjected to pulse heating, such as flash light exposure (with a light-to-heat conversion layer), the polarization was reversed even at temperatures as low as 55 or 60 degrees C under the application of a low electric field (30 MV/m). The mechanism which makes pulse heatin g effective in the latent image formation was pursued and a model was proposed which assumed a local field enhancement arising from a nonuni form temperature distribution in the film.