| 摘要 |
An image is reproduced and transferred onto a substrate by (a) providing a positive electrode having a continuous passivated surface moving at substantially constant speed along a predetermined path, said passivated surface defining a positive electrode active surface; (b) forming on the positive electrode active surface a plurality of dots of colored, coagulated colloid representative of a desired image, by electrocoagulation of an electrolytically coagulable colloid present in an electrocoagulation printin g ink containing a coloring agent; and (c) bringing a substrate into contact with the dots of colored, coagulated colloid to cause transfer of the colored, coagulated colloid from the positive electrode active surface onto the substrate and thereby imprint the substrate with the image. Step (b) is carried out by (i) providi ng a series of negative electrodes each having a surface covered with a passive oxide film, the negative electrodes being electrically insulated from one another and arranged in rectilinear alignment so that the surfaces thereof define a plurality of corresponding negative electrode active surfaces disposed in a plane spac ed from the positive electrode active surface by a constant predetermined gap, the negative electrodes being spaced from one another by a distance smaller than the electrode gap; (ii) coating the positive electrode active surface with a n olefinic substance to form on the surface micro-droplets of olefinic substance; (iii) filling the electrode gaps with the electrocoagulation printing ink; (iv) applying to the negative electrodes a pulsed bias voltage ranging from - 1.5 to -40 volts and having a pulse duration of 15 nanoseconds to 6 microseconds , the bias voltage applied being inversely and non-linearly proportional to th e pulse duration; (v) applying to selected ones of the negative electrodes a trigger voltage sufficient to energize same and cause point-by-point selective coagulation and adherence of the colloid onto the olefin-coated positive electrode active surface opposite the electrode active surfaces of the energized electrodes while the positive electrode active surface is moving, thereby forming the dots of colored coagulated colloid; and (vi) removing any remaining non-coagulated colloid from the positive electrode active surface. The invention enables one to obtain an image resolution as high as 400 lin es per inch, or more, without adverse effect.
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