Patent ID: 7191930

Claim:
A method for transferring particles from an electrode plate to tacky areas present on a substrate, comprising: a) placing a substrate having both tacky and non-tacky areas between first and second electrode plates, the substrate and electrode plates arranged substantially horizontally and stacked substantially vertically, wherein the first electrode plate (i) lies below the substrate, (ii) has a surface which faces tacky and non-tacky areas on the substrate, and (iii) is spaced from the substrate and the second electrode plate; b) applying particles over the surface of the first electrode plate; c) applying a direct current potential between the first and second electrode plates for a time T 1 , establishing a polarity on the first electrode and thereby causing the particles to be charged, and be propelled toward the second electrode plate and to the substrate resulting in at least a portion of the charged particles becoming adhered to tacky areas on the substrate; and d) changing the direct current potential to reverse the polarity on the first electrode plate for a time T 2 after step c) to cause at least some of the particles to leave the non-tacky areas of the substrate, be propelled against the first electrode plate, again be charged and propelled from the first electrode plate to the substrate, resulting in at least some of the particles that had been adhered to non-tacky areas prior to step d) being adhered to the tacky areas at the end of step d).