Method and apparatus for toner cake delivery

A method for delivery of a toner cake layer having a high solids content to a receiving surface on a receiving member, comprising the steps of:

• providing a supply of high solids content liquid developing material;
• receiving a quantity of such liquid developing material and providing therefrom a layer of liquid developing material on the receiving surface so as to form a primary toner cake layer;
• inducing in at least one of the high solids content liquid developing material and the primary toner cake layer a first induced charge at a first polarity, such that the primary toner cake layer exhibits a uniform charge at the first polarity;
• inducing, to a selectable depth, a second induced charge of a second, opposing polarity in the primary toner cake layer, whereby an inner layer of the primary toner cake layer is made subject to the first polarity charge and an outer layer of the primary toner cake layer is made subject to the second polarity charge;
• presenting at least a portion of the primary toner cake layer to the donor surface of a coating member and inducing a selectable bias differential between the donor surface and the receiving surface so as to cause the inner and outer layers to be respectively attracted to the receiving surface and the donor surface;
• and
• separating the donor surface and the receiving surface so as to cause the outer layer to be transferred to the donor surface while the inner layer remains on the receiving surface as a secondary toner cake layer.

A toner cake layer delivery apparatus for delivery of a toner cake layer having a high solids content to a receiving surface on a receiving member, comprising:

• a movable coating member aligned with the receiving member;
• a supply of high solids content liquid developing material;
• a liquid developing material applicator connected to the supply of high solids content liquid developing material and operable for receiving a quantity of such liquid developing material and for providing therefrom a layer of liquid developing material on the receiving surface so as to form a primary toner cake layer;
• first charge inducing means for inducing in at least one of the high solids content liquid developing material and the primary toner cake layer a first induced charge at a first polarity, such that the primary toner cake layer exhibits a uniform charge at the first polarity;
• second charge inducing means for inducing, to a selectable depth, a second induced charge of a second, opposing polarity in the primary toner cake layer, whereby an inner layer of the primary toner cake layer is made subject to the first polarity charge and an outer layer of the primary toner cake layer is made subject to the second polarity charge;
• and
• means for inducing a selectable bias differential between the donor surface and the receiving surface;
• wherein the receiving member is operable for presenting at least a portion of the primary toner cake layer to the donor surface and wherein the selectable bias differential causes the inner and outer layers to be respectively attracted to the receiving surface and donor surface, such that subsequent separation of the donor surface and the receiving surface causes the outer layer to be transferred to the donor surface while the inner layer remains on the receiving surface as a secondary toner cake layer.

An imaging system for effecting contact electrostatic printing of an output image, comprising:

• an imaging assembly having an imaging member, the imaging member having a receiving surface for receiving an electrostatic latent image thereon, the electrostatic latent image being representative of the desired output image;
• a toner cake layer delivery apparatus for delivery of a toner cake layer having a high solids content to the receiving surface on the imaging member, comprising:
• a supply of high solids content liquid developing material;
• a liquid developing material applicator connected to the supply of high solids content liquid developing material and operable for receiving a quantity of such liquid developing material and for providing therefrom a layer of liquid developing material on the receiving surface so as to form a primary toner cake layer;
• a coating member aligned with the liquid developing material applicator and the receiving member, the coating member having a donor surface, the movable coating member being operable for pressure contact at a process nip with the receiving surface;
• first charge inducing means for inducing in at least one of the high solids content liquid developing material and the primary toner cake layer a first induced charge at a first polarity, such that the primary toner cake layer receives a uniform charge at the first polarity;
• and
• second charge inducing means for inducing, to a selectable depth, a second induced charge of a second, opposing polarity in the primary toner cake layer, whereby an inner layer of the primary toner cake layer is made subject to the first polarity charge and an outer layer of the primary toner cake layer is made subject to the second polarity charge;
• and
• means for inducing a selectable bias differential between the donor surface and the receiving surface;
• wherein the receiving member is operable for presenting at least a portion of the primary toner cake layer to the donor surface and wherein the selectable bias differential causes the inner and outer layers to be respectively attracted to the receiving surface and donor surface, such that subsequent separation of the donor surface and the receiving surface causes the outer layer to be transferred to the donor surface while the inner layer remains on the receiving surface.