Method and apparatus for removing excess developing liquid from

Abstract

A deformable polyurethane roller, which may be either a squeegee roller or a blotting roller, is positioned to contact a liquid-developed electrostatic image on a photoconductor. The polyurethane roller has a resistivity of 10.sup.9 ohm-centimeters or less and a Shore A hardness of 45 or less. The roller is biased by a potential having a sign the same as the sign of the charged toner particles in a liquid developer which comprises an insulating liquid having charged toner particles disseminated therethrough. The bias on the polyurethane roller is such that it prevents streaking, smearing, tailing or distortion of the developed electrostatic image and removes so much of the liquid carrier of the liquid developer from the surface of the photoconductor that the just-moist developed image can be transferred to a carrier sheet. This enables a higher-boiling insulating liquid to be used as the carrier liquid in a liquid developer. The polyurethane roller is driven so the relative motion between its surface and the surface of the photoconductor is substantially zero. In one form of the invention, the roller is a squeegee roller; in another form of the invention, the roller is a blotting roller formed with closed-cell polyurethane foam formed with open surface pores. Means are provided for squeezing liquid absorbed by the pores from the pores so as to continuously present open dry pores for blotting the liquid from the liquid-developed image. After development, the developed image can be transferred to a carrier sheet, as is known to the art.