| abstract |
An electrophoretic migration imaging process, apparatus, and materials useful therein are disclosed. Electrically photosensitive particles, at least some of which bear a positive polarity electrostatic charge, are disposed between two spaced electrodes. One of the electrodes has the surface thereof adjacent to the electrically photosensitive particles bearing a uniform layer containing an amount of a dark charge exchange material sufficient to provide a net change in charge polarity with at least a portion of said positive polarity particles upon electrical contact therewith in the presence of an electric field and in the absence of activating radiation. Imaging is accomplished by A. DISPOSING THE ELECTRICALLY PHOTOSENSITIVE PARTICLES BETWEEN THE SPACED ELECTRODES, AND B. SUBSTANTIALLY SIMULTANEOUSLY 1. ESTABLISHING A POTENTIAL DIFFERENCE BETWEEN SAID ELECTRODES TO CREATE AN ELECTRIC FIELD SUCH THAT AT LEAST A PORTION OF THE POSITIVE POLARITY ELECTRICALLY PHOTOSENSITIVE PARTICLES MOVE INTO ELECTRICAL CONTACT WITH THE LAYER OF DARK CHARGE EXCHANGE MATERIAL, AND 2. IMAGEWISE EXPOSING THE ELECTRICALLY PHOTOSENSITIVE PARTICLES TO ACTIVATING RADIATION SUCH THAT AT LEAST A PORTION OF THE EXPOSED, POSITIVE POLARITY PARTICLES ARE IMMOBILIZED AT THE SURFACE OF THE LAYER OF DARK CHARGE EXCHANGE MATERIAL AND AT LEAST A PORTION OF THE UNEXPOSED, POSITIVE POLARITY PARTICLES UNDERGO A NET CHANGE IN CHARGE POLARITY UPON ELECTRICAL CONTACT WITH THE LAYER OF DARK CHARGE EXCHANGE MATERIAL AND ARE REPELLED THEREFROM. |