IMAGING SYSTEM

Abstract: An apparatus for enhancement of liquid toner image transfer includes an image bearing surface, apparatus for forming a liquid toner image on the image bearing surface, a second surface arranged for movement relative to the image bearing surface whereby regions of the image bearing surface and the second surface sequentially come into propinquity and subsequently move out of propinquity. The apparatus for enhancement further includes potential impression apparatus associated with at least one portion of at least one of the image bearing surfaces and the second surface for impressing a potential on said at least one portion and apparatus for energizing the potential impression apparatus only when said at least one portion is located at predetermined locations along the pathway, thereby to provide image rigidization.

Description: IMAGING SYSTEM FIELD OF THE INVENTION The present invention relates to image transf techniques and apparatus for use in electrophotography. BACKGROUND OF THE INVENTION Liquid toner images are developed by varying t density of pigmented solids in a developer material on latent indigo image bearing surface in accordance with imaged pattern. The variations in density are produced the corresponding pattern of an electric field extendi outward from the latent image bearing surface, which configured by the different latent image and backgrou voltages on the latent image bearing surface and a volta on a developer plate or roller. In general, developed liquid toner images are neith solid nor homogeneous. Typically, a liquid toner develop contains about 1.5% to 2% solids and a developed ima contains about 15% - 25% solids. The developed image has higher density closer to the latent image bearing surfa and a "fluffy", i.e. loosely bound, region furthest aw from the latent image bearing surface. In order to improve transfer of a clean developed ima from the latent image bearing surface to a substrate it most desirable to ensure that, before transfer, t pigmented solids adjacent background regions a substantially removed and that the density of pigment solids in the developed image is increased, there compacting or rigidizing the developed image. The compacti or rigidizing of the developed image increases the ima viscosity and enhances the ability of the image to mainta its integrity under the stresses encountered during ima transfer. It is also desirable that excess liquid be remov from the latent image bearing surface before transfer. It is known in the prior art, as described in U.S Patent 3,955,533, to employ a reverse roller spaced abo 50 microns from the latent image bearing surface to she off the carrier liquid and pigmented solids in the regi beyond the outer edge of the image and thus leave relativel clean areas above the background. The technique of removing carrier liquid is known generally as metering. An alternative metering technique, described in U.S. Patents 3,767,300 and 3,741,643, employs an air knife, but has not been particularly successful due to sullying of the background as a result of turbulence and consequent mixing of the background inversion layer with the surface layer of the carrier liquid. In U.S. Patent 3,957,016, the use of a positive biased metering roller is proposed wherein the metering roller is maintained at a voltage intermediate the image and background voltages to clean the background while somewhat compacting the image. In the prior art it is known to effect image transfer wherein the image is brought into contact with a substrate backed by a charged roller. Unless the image is rigidize before it reaches the nip of the latent image bearing surface and the roller, image squash and flow may occur. This is particularly true if the substrate is a non-porous material, such as plastic. In the prior art, liquid toner images are generall transferred to substrates by electrophoresis, whereby th charged image moves from the latent image bearing surface t the substrate through the carrier liquid under the influenc of an electric field produced by a high voltage, associate with the substrate, which is of opposite polarity to th charge on the image particles. The voltage and thus the field strength available fo electrophoretic transfer are limited by the danger o electrical breakdown which can occur at both the input an output edges of the nip, due to the minimum of the Pasche curve being at about 8 microns. Thus, according to th Paschen curve, the voltage difference at the nip canno exceed about 360 volts, if possible damage to the image an possible damage to the latent image bearing surface due t electrical breakdown are to be avoided. Electrophoretic compaction of images prior to transfe thereof is described in U„S. Patent 4,286,039 which shows metering roller followed by a negatively biased squeege roller. The squeegee roller is operative both for compactin the image and for removing excess liquid. The voltage tha can be applied to the squeegee roller is also limited by th danger of electrical breakdown. The breakdown problem i least serious at the input to the squeegee roller since th meniscus present there acts to increase the minimu effective air gap. In the image areas, the breakdown proble is more severe since the fields produced by the squeege roller and by the latent image bearing surface add. Th problem is most severe at the exit edge of the . squeege roller at which a meniscus is substantially not present. In U.S. Patent 4,684,238 an un etered image i initially transferred to an intermediate transfer member an is then metered by a metering roller having a voltage o opposite polarity to the charge on the toner particle making up the image. No discussion of the problem o electrical breakdown is presented. SUMMARY OF THE INVENTION The present invention seeks to provide improve apparatus for enhancement of image transfer. There is thus provided in accordance with a preferre embodiment of the present invention apparatus fo enhancement of liquid toner image transfer including a image bearing surface, means for forming a liquid tone image on the image bearing surface, a second surfac arranged for movement relative to the image bearing surfac whereby regions of the image bearing surface and the secon surface sequentially come into propinquity and subsequentl move out of propinquity, potential impression mean associated with at least one portion of at least one of th image bearing surface and the second surface for impressin a potential on the at least one portion, and means fo energizing the potential impression means only when the a " least one portion are located at predetermined location along the pathway, thereby to provide image rigidization. Further in accordance with a preferred embodiment o the present invention, the potential impression mean includes a plurality of electrical conductors associated wi at least one of the image bearing surface and the secon surface. There is also provided in accordance with a furthe preferred embodiment of the present invention apparatus fo image transfer including an image bearing surface, an imag compacting surface arranged for operative engagement wit the image bearing surface and having formed therein at leas one electrical conductor, and means for energizing the a least one electrical conductor at a location interior wit respect to the engagement of the image compacting surfac and the image bearing surface whereby a relatively hig voltage difference may be developed between the imag compacting surface and the image bearing surface. Further in accordance with a preferred embodiment o the present invention, the liquid toner image includes imag regions and background regions, the apparatus includin means for removing pigmented toner particles from th background regions defined on the image bearing surface, an squeegee means for removing excess liquid from the liqui image after rigidization thereof, prior to transfer of th image to a substrate. Still further in accordance with a preferre embodiment of the present invention, the toner imag includes charged toner particles, the second surface is th surface of a roller and moves opposite to the image bearin surface, and the potential impression means includes mean for impressing upon a first region on the second surface first potential to provide background cleaning and fo impressing upon a second region of the second surface second potential of the same polarity as the polarity of th toner particles providing rigidization of the liquid tone image on the image bearing surface. Additionally in accordance with a preferre embodiment of the present invention, the apparatus als includes means for energizing the electrical conductors thereby to provide a desired electrical field at a desire location for producing image rigidization thereat. Still further in accordance with a preferr embodiment of the present invention, the second surfa includes a rotatable surface. Further in accordance with a preferred embodiment o the present invention, the second surface includes a stati surface relative to which the image bearing surface moves. Additionally in accordance with a preferred embodimen of the present invention, the apparatus includes a intermediate transfer member for receiving the liquid tone image from the image bearing surface after rigidizatio thereof, for transfer of the image to a substrate. Further in accordance with a preferred embodiment o the present invention, the liquid toner image includes imag regions and background regions, and the apparatus include means for removing pigmented toner particles from th background regions defined on the image bearing surface, an squeegee means for removing excess liquid from the liqui image after rigidization thereof, prior to transfer of th image to a substrate. Still further in accordance with a preferre embodiment of the present invention, energization of the a least one electrical conductor provides a desired electrica field at a desired location for producing imag rigidization. Additionally in accordance with a preferred embodimen of the present invention, the apparatus includes a intermediate transfer member for receiving the toner imag from the image bearing surface after rigidization thereof for transfer of the image to a substrate. Further in accordance with a preferred embodiment o the present invention, the liquid toner image on the imag bearing surface includes image regions and backgroun regions, and the apparatus includes means for removin pigmented toner particles from the background region defined on the image bearing surface, and squeegee means fo removing excess liquid from the liquid toner image afte rigidization thereof, prior to transfer of the image to substrate. Additionally in accordance with a preferred embodimen of the present invention, the toner image includes charge toner particles, the second surface is the surface of roller and moves opposite to the movement of the imag bearing surface, and the potential impression means include means for impressing on at least one of the plurality o conductors, a first potential of a polarity opposite to th polarity of the toner particles to provide backgroun cleaning and impressing upon a second conductor associate with at least one of the plurality of conductors, a secon potential of the same polarity as the polarity of the tone particles providing rigidization of the liquid toner imag on the image bearing surface. Further in accordance with a preferred embodiment o the present invention, the second surface is the surface o a roller and the surface moves opposite to the movement o the image bearing surface thereby providing metering o excess liquid on the image bearing surface. Still further in accordance with a preferr embodiment of the present invention, the operati engagement includes an entrance region, an exit region and third region therebetween, and the energizing means associated only with the third region. Additionally in accordance with a preferred embodime of the present invention, the first potential is of polarity opposite to the polarity of the toner particles. In accordance with a further preferred embodiment the present invention, there is provided apparatus for ima transfer including an image bearing surface arranged support a liquid toner image, including image regions a background regions thereon, means for rigidizing the ton image at the image regions, and an intermediate transf member for receiving the toner image from the image beari surface after rigidization thereof, for transfer of t image to a substrate. Additionally in accordance with a preferred embodime of the present invention, the apparatus includes squeeg means for removing excess liquid from the toner image aft rigidization thereof, prior to transfer of the image to th intermediate transfer member. Further in accordance with a preferred embodiment o the present invention, the apparatus also includes means fo removing excess liquid from the image bearing surface. Still further in accordance with a preferre embodiment of the present invention, the means fo rigidizing includes a rigidizing roller maintained at potential opposite to the potential of image areas of th image bearing surface and which does not contact the image and the apparatus also includes means for removing pigmente toner particles from the background regions, and means fo removing excess liquid from the image bearing surface. Additionally in accordance with a preferred embodimen of the present invention, the means for rigidizing include a second surface arranged for movement relative to th image bearing surface along a pathway whereby portions o the image bearing surface and the second surfac sequentially come into propinquity and subsequently move ou of propinquity, potential impression means associated wit at least one portion of at least one of the image bearin surface and the second surface for impressing a potential o the at least one portion, and means for energizing th potential impression means only when the at least on portion is located at a predetermined location along th pathway, thereby to provide image rigidization. Further in accordance with a preferred embodiment o the present invention, the potential impression mean includes a plurality of electrical conductors associate with at least one of the image bearing surface and th second surface. Still further in accordance with a preferred embodimen of the present invention, the second surface is arranged fo operative engagement with the image bearing surface and ha formed therein at least one electrical conductor, and th apparatus also includes means for energizing the at leas one electrical conductor at an interior location wit respect to the engagement of the second surface and th image bearing surface whereby a relatively high voltag difference may be developed between the interior location o the second surface and the image bearing surface. Additionally in accordance with a preferred embodimen of the present invention, the potential impression mean includes means for impressing a first portion of the secon surface with a first potential of a first polarity an simultaneously impressing a second portion of the secon surface with a second potential of a second polarity. Still further in accordance with a preferred embodimen of the present invention, a toner image formed of pigmente particles having a charge of the second polarity is provide on the image bearing surface, and the first potential on th first portion provides background cleaning and the secon potential on the second portion provides rigidization of th toner image on the image bearing surface. Further in accordance with a preferred embodiment o the present invention, the second surface is the surface o a roller and the surface moves in a direction opposite t the movement of the image bearing surface thereby providin metering of excess liquid on the image bearing surface. Additionally in accordance with a preferred embodimen of the present invention, the second surface is the surfac of a roller and the surface moves oppositely to the movemen of the image bearing surface. Still further in accordance with a preferred embodimen of the present invention, energization of the electrica conductors provides a desired electrical field at a desire location for producing image rigidization. Additionally in accordance with a preferred embodimen of the present invention, the means for rigidizing include a rotatable surface which operatively engages the image. Further in accordance with a preferred embodiment o the present invention, the means for rigidizing includes static surface relative to which the image bearing surfac moves. Still further in accordance with a preferred embodimen of the present invention, the static surface includes a least one electrical conductor and energization of the a least one electrical conductor provides a desired electrica field at a precise location for producing imag rigidization. Additionally in accordance with a preferred embodimen of the present invention, the means for rigidizing include a squeegee roller maintained at a potential opposite to th potential of image areas of the image bearing surface an which simultaneously compacts the image and removes exces liquid from the image. There is also provided in accordance with yet a furthe embodiment of the present invention, apparatus for imag transfer including an image bearing surface arranged t support a liquid toner image including image regions an background regions thereon, means for rigidizing the liqui toner image at the image regions including a member havin an elastic outer layer having at least one ply of elasti material whose outer surface is arranged for movemen relative to the image bearing surface along a pathwa whereby regions of the image bearing surface and the oute surface sequentially come into propinquity and subsequentl move out of propinquity, and potential impression mean contained within at least one portion of the elastic oute layer for impressing a potential on the at least one portio when the at least one portion is in propinquity with th image bearing surface to apply a potential therebetween, an an intermediate transfer member for receiving the tone image from the image bearing surface after rigidizatio thereof, for transfer of the image to a substrate. There is also provided in accordance with yet a furthe preferred embodiment of the present invention a method fo imaging including the steps of forming a liquid toner imag on an image bearing surface, rigidizing the liquid tone image, transferring the rigidized image to an intermediat transfer member and subsequently transferring the image to final substrate. Further in accordance with a preferred embodiment o the present invention, the at least one ply of elasti material includes at least two plies and the potentia impression means is placed between the two plies. Still further in accordance with a preferred embodiment of the present invention, the static surface engages the image bearing surface in an entrance region, an exit region and a third region therebetween, and the energizing means is associated only with the third region. The propinquity may or may not include touching engagement. Additionally in accordance with a preferred embodiment of the present invention, the second surface is a static surface relative to which the image bearing surface moves. There is also provided in accordance with another preferred embodiment of the present invention apparatus for image transfer including an image bearing surface arranged to support a liquid toner image thereon, including image regions and background regions, rigidizing means for rigidizing the toner image at the image regions, and squeegee means separate from the rigidizing means for removing excess liquid from the toner image afte rigidization thereof, prior to transfer of the image to a substrate. Further in accordance with a preferred embodiment o the present invention, the liquid toner image includes charged toner particles and the apparatus also includes means for removing pigmented toner particles from the background regions a background cleaning roller, and th rigidizing means includes a rigidizing roller maintained a a potential having a sign opposite to the sign of the charg on the charge toner particles. Still further in accordance with a preferred embodimen of the present invention, the rigidizing means includes second surface arranged for movement relative to the imag bearing surface along a pathway whereby portions of th image bearing surface and of the second surface sequentiall come into propinquity and subsequently move out o propinquity, potential impression means associated with a least one portion of at least one of the image bearin surface and the second surface for impressing a potential the at least one portion, and means for energizing th potential impression means only when the at least on portion is located at a predetermined location along th pathway, thereby to provide image rigidization. Additionally in accordance with a preferred embodimen of the present invention, the potential impression mean includes a plurality of electrical conductors associate with at least one of the image bearing surface and th second surface. Further in accordance with a preferred embodiment o the present invention, the rigidizing means includes a image compacting surface arranged for operative engagemen with the image bearing surface, the image compacting surfac having formed thereon at least one electrical conductor, an means for energizing the at least one electrical conducto at an interior location with respect to the engagement o the image compacting surface and the image bearing surfac whereby a relatively high voltage difference may b developed between the image compacting surface and the imag bearing surface. Still further in accordance with a preferred embodimen of the present invention, the potential impression mean includes means for impressing a first potential of a firs polarity onto a first portion of the second surface an for simultaneously impressing a second potential of a secon polarity onto a second portion of the second surface. Additionally in accordance with a preferred embodimen of the present invention, a liquid toner image formed o pigmented particles having a charge of the second polarit is provided onto the image bearing surface, and the firs potential on the first portion provides background cleanin and the second potential on the second portion provide rigidization of the toner image on the image bearin surface. Further in accordance with a preferred embodiment o the present invention, the second surface is the surface o a roller and the second surface moves in a directio opposite to the movement of the image bearing surface there providing metering of excess liquid on the image bearin surface. Additionally in accordance with a preferred embodimen of the present invention, energization of the electrica conductors provides a desired electrical field at a desire location for producing image rigidization. Still further in accordance with a preferred embodimen of the present invention, the rigidizing means includes rotatable surface. Additionally in accordance with a preferred embodimen of the present invention, the image compacting surfac includes a static surface relative to which the imag bearing surface moves. Further in accordance with a preferred embodiment o the present invention, the second surface is the surface o a roller and the second surface moves in a directio opposite to the movement of the image bearing surfac thereby providing metering of excess liquid on the imag bearing surface. Still further in accordance with a preferred embodimen of the present invention, the apparatus includes a intermediate transfer member for receiving a toner imag from the image bearing surface after rigidization thereof for transfer of the image to a substrate. Additionally in accordance with a preferred embodimen of the present invention, the operative engagement include an entrance region, an exit region and a third regio therebetween and the energizing means is associated onl with the third region. There is also provided in accordance with anothe preferred embodiment of the present invention apparatus fo image transfer including an image bearing surface and a image receiving member including an elastic outer laye having at least one ply of elastic material defining a outer image receiving surface arranged for relative movemen along a pathway whereby regions ' of the image bearing surfac and the image receiving surface sequentially come int propinquity for image transfer therebetween and subsequent move out of propinquity following image transfe therebetween, potential impression means contained within a least one portion of the elastic outer layer for impressin a potential between the at least one portion and the imag bearing surface, and means for energizing the potentia impression means only when the at least one portion i located at a predetermined location along the pathway thereby to provide desired image transfer enhancement. Further in accordance with a preferred embodiment o the present invention, the potential impression mean includes a plurality of electrical conductors. Still further in accordance with a preferred embodimen of the present invention, the potential impression mean includes means for impressing a potential of a firs polarity opposite to the polarity of the charge on the imag particles. Additionally in accordance with a preferred embodimen of the present invention, the potential impression mean includes means for impressing a first potential on the a least one portion when the at least one portion is locate at a first predetermined location and for impressing second potential on the at least one portion when the a least one portion is located at a second predetermine location adjacent the first predetermined location. Further in accordance with a preferred embodiment o the present invention, the potential impression mean includes means for simultaneously impressing a firs potential on a first portion of the at least one surface an a second potential on a second portion of the at least on surface adjacent the first portion. Still further in accordance with a preferred embodimen of the present invention, the potential impression mean includes means for impressing a first potential on a firs portion of the at least one surface when the first portio is located at a first predetermined location and fo impressing a second potential on the first portion when th first portion is located at a second predetermined locatio adjacent the first predetermined location, and simultaneously impressing the second potential on the second portion when it is located at the second predetermined location and the first potential on the second portion when it is located at the first location. Additionally in accordance with a preferred embodiment of the present invention, the potential impression means includes means for simultaneously impressing a first potential on a first portion of the at least one surface when the first portion is located at a first predetermined location and a second potential on a second portion of the at least one surface when the second portion is located at a second predetermined location, and means for simultaneously impressing the second potential on the first portion when the first portion is located at the second predetermined location and the first potential on a third portion when it is located at the first location. Further in accordance with a preferred embodiment of the present invention, the first and second potentials are of opposite polarity. Additionally in accordance with a preferred embodimen of the present invention, the plurality of electrical conductors include first and second arrays of electrical conductors arranged on the image receiving surface and th means for electrically energizing include first means fo selectably energizing at least one electrical conductor o the first array for providing a desired potential at a firs predetermined location, and second means for selectabl energizing at least one electrical conductor of the secon array for providing desired heating of the image receivin surface at a second predetermined location. Further in accordance with a preferred embodiment o the present invention, the apparatus includes means fo removing excess liquid from the image bearing surface. Still further in accordance with a preferred embodimen of the present invention, the potential impression mean provides a desired electrical field at a desired locatio for producing electrophoretic image transfer thereat. Additionally in accordance with a preferred embodimen of the present invention, the apparatus also includes mean for subsequently transferring the image from the imag receiving member and energization of the at least on conductor of the second array provides desired resistanc heating of the image prior to the subsequent transfer. Further in accordance with a preferred embodiment o the present invention, the image bearing surface is arrange to support a liquid toner image thereon, including imag regions and background regions, and the apparatus include means for removing pigmented toner particles from th background regions defined on the image bearing surface. Still further in accordance with a preferred embodimen of the present invention, the means for removing includes roller with a potential intermediate that of the imag regions and the background regions. Additionally in accordance with a preferred embodimen of the present invention, the potential impression mean includes means for impressing a potential of a firs polarity, the same as that of the polarity of the charge o the image particles, on at least one conductor in a firs region and for impressing a potential of a second polarity, opposite to to that of the polarity of the charge on th image particles, on at least one conductor in a second region adjacent the first region to provide image transfer to the image receiving member at the first region and image rigidization at the second region. Still further in accordance with a preferred embodimen of the present invention, the plurality of electrical conductors include first and second arrays of electrical conductors arranged on the image receiving surface and th means for electrically energizing include first means fo selectably energizing at least one electrical conductor of the first array for providing a desired potential at a first given location on the image receiving surface, and secon means for selectably energizing at least one electrical conductor of the second array for providing desired heating of the image receiving surface at a second given location. Additionally in accordance with a preferred embodiment of the present invention, the apparatus also includes second transfer means for image transfer from the image receiving surface to a substrate. There is also provided in accordance with yet a further preferred embodiment of the present invention apparatus for image transfer including an image bearing surface and an image receiving surface arranged for relative movement along a pathway whereby regions of the image bearing surface and the image receiving surface sequentially come into propinquity for image transfer therebetween and subsequently move out of propinquity following image transfer therebetween, potential impression means associated with at least one portion of at least one of the image bearing surface and the image receiving surface for simultaneously impressing a first potential on a first portion of the at least one surface and a second potential on an adjacent second portion of the at least one surface, and means for energizing the potential impression means to impress the first potential only when the first portion is located at a predetermined location along the pathway, thereby to provide desired image transfer enhancement along the first portion and simultaneous image rigidization along the adjacent second portion. There is additionally provided in accordance with a further preferred embodiment of the present invention apparatus for image transfer of a liquid toner image including an image bearing surface, adapted to carry the liquid toner image and electrically insulating carrie liquid thereon, an image receiving surface arranged fo relative movement along a pathway whereby regions of th image bearing surface and the image receiving surfac sequentially ' come into propinquity at an image transfe region for image transfer therebetween and subsequently mov out of propinquity following image transfer therebetween, wherein the liquid toner image and carrier liquid fill first section of the region between the image bearing an image receiving surfaces, potential impression mean associated with at .least one portion of at least one of t image bearing surface and the image receiving surface f impressing a potential on the at least one portion, an means for energizing the potential impression means when th at least one portion is located completely within the firs section. Further in accordance with a preferred embodiment o the present invention, the at least one ply of elasti material includes at least two plies of elastic material an the potential impression means is located between the tw plies. There is also provided in accordance with a preferre embodiment of the present invention apparatus for imag transfer including an image bearing surface, an imag receiving member including an outer layer defining an oute image receiving surface, arranged for relative movemen along a pathway whereby regions of the image receivin surface and the image bearing surface come into propinquit for image transfer therebetween and subsequently move out o propinquity following image transfer therebetween electrical potential impression means contained within th outer layer including a plurality of electrical* conductors means for energizing the electrical potential impressio means to provide improved image transfer from the imag bearing surface to the image receiving surface, and mean for subsequently transferring the image to a fina substrate. Further in accordance with a preferred embodiment o the present invention, the plurality of electrica conductors include first and second arrays of electrica conductors and the means for energizing includes firs means for energizing at least one electrical conductor o the first array for providing a desired potential at a firs predetermined location, and second means for energizing a least one conductor of the second array for providin desired heating of the image receiving surface. There is also provided in accordance with yet a furthe preferred embodiment of the present invention apparatus fo transferring an image including an image bearing surface, an image receiving member including an outer layer defining an outer image receiving surface, arranged for relative movement along a pathway whereby regions of the image receiving surface and the image bearing surface come into propinquity for image transfer therebetween and subsequently move out of propinquity following image transfer therebetween, potential impression means associated with one of the image bearing and image receiving surfaces for simultaneously impressing a first potential on a first portion of the at least one surface and a second potential on an adjacent second portion of the at least one surface, and means for energizing the potential impression means to impress the first potential only when the first portion is located at a predetermined location along the pathway, to provide desired image transfer enhancement along the first portion and simultaneous image rigidization along the adjacent second portion. Further in accordance with a preferred embodiment of the present invention, the outer layer includes an elastic outer layer having at least one ply of elastic material. Still further in accordance with a preferred embodimen of the present invention, the potential impression means is contained within the outer layer. Additionally in accordance with a preferred embodimen of the present invention, the potential impression means includes a plurality of electrical conductors. Further in accordance with a preferred embodiment o the present invention, the first and second potentials ar of opposite polarity. Still further in accordance with a preferred embodimen of the present invention, the image bearing surface i arranged to support a liquid toner image thereon, includin image regions and background regions, the apparatu including means for removing pigmented toner particles fro the background regions defined on the image bearing surface Additionally in accordance with a preferred embodimen of the present invention, the image is a liquid toner imag including carrier liquid and charged toner particles and t first potential is of the same sign as the sign of the ton particles and the second potential is of opposite sign that of the toner particles. Further in accordance with a preferred embodiment the present invention, the apparatus also includes seco transfer means for image transfer from the image receivi surface to a substrate. Still further in accordance with a preferred embodimen of the present invention, the at least one ply of elasti material includes at least two plies of elastic material an the potential impression means is placed between the tw plies. Additionally in accordance with a preferred embodimen of the present invention, the propinquity includes touchin engagement. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood an appreciated more fully from the following detaile description, taken in conjunction with the drawings i which: Fig. 1 is a simplified sectional illustration o electrophotographic apparatus constructed and operative i accordance with a preferred embodiment of the presen invention; Fig. 2 is a simplified sectional illustration o electrophotographic apparatus constructed and operative i accordance with another preferred embodiment of the presen invention; Fig. 3A is a simplified conceptual sectiona illustration of image transfer apparatus constructed an operative in accordance with a preferred embodiment of th present invention; Fig. 3B is a simplified conceptual sectiona illustration of image transfer apparatus constructed an operative in accordance with another preferred embodiment o the present invention; Fig. 4 is a simplified sectional illustration of par of an intermediate transfer member constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 5 is a simplified sectional illustration of part of an intermediate transfer member constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 6 is an illustration of part of the apparatus of Fig. 3A and illustrating the supply of potential to the intermediate transfer member; Fig. 7 is a pictorial illustration of the arrangement of conductors on the intermediate transfer member employed in the apparatus of Fig. 6; Fig. 8 is a simplified side view illustration of the arrangement of electrical supply apparatus in association with an intermediate transfer member; Fig. 9 is a side view illustration taken along lines IX - IX in Fig. 8 for one embodiment of the invention; Fig. 10 is a simplified illustration of electrical supply apparatus useful in the arrangement of Fig. 8; Fig. 11 is a simplified sectional illustration of electrophotographic apparatus constructed and operative in accordance with another preferred embodiment of the present invention; Fig. 12 is a simplified conceptual sectional illustration of image rigidization apparatus constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 13 is a simplified conceptual sectional illustration of image rigidization apparatus constructed and operative in accordance with another preferred embodiment of the present invention; and Fig. 14 is a simplified sectional illustration o electrophotographic apparatus constructed and operative i accordance with yet another preferred embodiment of th present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Reference is now made to Fig. 1 which illustrate electrophotographic imaging apparatus constructed an operative in accordance with a preferred embodiment of th present invention. This and other embodiments of th invention are described for the case of liquid toner system with negatively charged particles, and positively charge photoconductors. For positively charged toner, th polarities of the voltages given would be reversed. In a preferred embodiment of the invention the toner o example 1 of U. S. Patent 4,794,651 the disclosure of whic is included herein by reference, can be used, but a variet of liquid toner types are useful in the practice of th invention. As in conventional electrophotographic systems, th apparatus of Fig. 1 comprises a drum 10 arranged fo rotation about an axle 12 in a direction generally indicate by arrow 14. The drum 10 is formed with a cylindrica photoconductive surface 16. A corona discharge device 18 is operative to generall uniformly charge the photoconductor surface 16 with positive charge. Continued rotation of the drum 10 bring the charged photoconductor surface 16 into image receivin relationship with an exposure unit including a lens 20 which focuses a desired image onto the charge photoconductor surface 16, selectively discharging th photoconductor surface, thus producing an electrostati latent image thereon. Continued rotation of the drum 10 brings the charge photoconductor surface 16 bearing the electrostatic laten image into a development unit 22 including developmen electrodes 24, which is operative to apply a liquid toner t develop the electrostatic latent image. In accordance with a preferred embodiment of th invention, following application of toner thereto, th photoconductor surface 16 passes a typically positivel charged rotating roller 26, preferably rotating in direction indicated by an arrow 28. Typically the spatia separation of the roller 26 from the photoconductor surfac 16 is about 50 microns. Preferably the charge on roller 26 is intermediate th voltages of the latent image areas and of the backgroun areas on the photoconductor surface. Typical voltages are: roller 26: 200V, background area: 50V and latent imag areas: up to 1000V. It is appreciated that roller 26 may rotate in th direction opposite to that indicated by arrow 28 an function as a metering roller thereby to reduce th thickness of liquid on the photoconductor surface 16. Alternatively, the metering function may be eliminate at this stage or carried out downstream by an appropriat technique. In any event, the liquid which passes the roller 2 should be relatively free of pigmented particles except i the region of the latent image. Downstream of roller 26 there is preferably provided rigidizing roller 30. The rigidizing roller 30 is preferabl formed of a resilient polymeric material, such as conductiv resilient polymeric materials as described in either or bot of U.S. Patents 3,959,574 and 3,863,603 and is preferabl maintained in non-contacting spatial relationship with th photoconductive surface 16. According to one embodiment of the invention, roller 3 is lightly urged against the photoconductive surface 16 a by a spring mounting (not shown) . Rotation of th photoconductive surface 16 produces hydrodynamic forces o roller 30 which push it slightly away from th photoconductive surface 16, so that it typically lies at separation of 15 microns from the photoconductive surface. According to an alternative embodiment of the presen invention, the roller 30 may be mounted at a fixe separation from photoconductive surface 16. In such a case to take account of surface irregularities, the roller 3 lies at a separation of about 50 microns from th photoconductive surface. The surface of roller 30 typicall moves in the same direction as the photoconductive surfac so as not to substantially remove liquid from the image Preferably the nip between the roller 30 and th photoconductive surface 16 is kept wet so as to minimiz problems of electrical discharge. Various constructions o rigidizing rollers which reduce problems of electrica discharge are described hereinbelow. In an embodiment of the invention, the biased squeege described in U. S. Patent 4,286,039, the disclosure of whic is incorporated herein by reference, is used as the rolle 30. A negative voltage of between several hundred to 200 volts can be used and some breakdown is experienced. Rolle 30 is negatively charged to a potential of at least severa hundred and up to 2000 volts with the same sign as th charge on the pigmented toner particles, so that it repel similarly charged pigmented particles and causes them t more closely approach the image areas of the photoconducto surface 16, thus compressing and rigidizing the image. Downstream of rigidizing roller 30 there is provided a intermediate transfer member 40, which rotates in direction opposite to that of photoconductor surface 16, a shown by arrow 41, and is operative for receiving the tone image therefrom and for transferring the toner image to receiving substrate 42, such as paper. Various types of intermediate transfer members ar known and are described, for example, in U.S. Paten 4,684,238 and in assignee's copending U.S. Paten application entitled METHOD AND APPARATUS FOR IMAGING USIN AN INTERMEDIATE TRANSFER MEMBER filed January 4, 1989, th disclosures of which are incorporated herein by reference. Particularly beneficial constructions of intermediat transfer members in accordance with the present inventio are described in detail hereinbelow. Transfer of the image to intermediate transfer membe 40 is preferably aided by providing electrification of th intermediate transfer member 40 to a voltage of polarit opposite to that of the charged particles, although othe methods known in the art may be employed. Subsequent transfer of the image to substrate 42 is preferably aided by heat and pressure, with pressure applied by backer rolle 43, although other methods known in the art may be employed. It has been noted that when the negatively biase squeegee roller of U.S. Patent 4,286,039, with high negativ voltage, is utilized as the roller 30, the positive voltag on the intermediate transfer member required to transfer th image thereto is sharply reduced, typically from about 1000 volts or more to about 500 volts. It is believed that thi reduction is possibly due to a discharge of the charges i the image area of the image bearing surface and to charging of the background areas of the image bearin surface. Following transfer of the toner image to th intermediate transfer member, the photoconductive surface 16 is engaged by a cleaning roller 50, which typically rotates in a direction indicated by an arrow 52, such that it surface moves- in a direction opposite to the movement of th adjacent photoconductive surface 16 which it operativel engages. The cleaning roller 50 is operative to scrub clea the surface 16. A cleaning material, such as toner, may b supplied to the cleaning roller 50, via a conduit 54. wiper blade 56 completes the cleaning of the photoconductiv surface. Any residual charge left on the photoconductiv surface 16 is removed by flooding the photoconductor surfac with light from a lamp 58. Reference is now made to Fig. 2 which illustrate electrophotographic imaging apparatus constructed an operative in accordance with another preferred embodiment o the present invention. The apparatus of Fig. 2 shares man common elements with that of Fig. 1. These elements ar indicated by identical reference numerals, and for the sak of conciseness are not described herein a second time. The embodiment of Fig. 2 differs from that of Fig. 1 i that the rigidizing roller 30 is eliminated and further i that a belt-type, instead of roller type, intermediat transfer member 70 is employed. Belt-type intermediat transfer members are well known in the art and ar described, inter alia, in U.S. Patents 3,893,761; 4,684,23 and 4,690,539, the disclosures of which are incorporate herein by reference. It will be appreciated that the belt-type intermediat transfer member may be employed in the apparatus of Fig. and that the rigidizing roller 30 may be omitted in th embodiment of Fig. 1 or added to the embodiment of Fig. 2. Intermediate transfer member 70 is preferably charge so as to provide electrophoretic transfer of the image fro the photoconductive surface 16 thereto. Within given limits, the efficiency of electrophoretic transfer of the image ca be enhanced by increasing the potential difference betwee the photoconductive surface 16 and the intermediate transfe member 70. Increase in the potential difference between th photoconductive surface 16 and the intermediate transfe member 70 is limited, however, by the danger of electrical breakdown, which increases with an increase in potential difference. The interrelationship between the minimum voltage difference at which breakdown occurs across a gap and the gap separation is given by the well-known Paschen curve. I air, the minimum breakdown voltage for a gap between tw surfaces typically occurs, for a gap separation of about 8 microns, at a voltage difference of about 360V. Th breakdown voltage increases significantly for gaps eithe smaller or larger than the indicated gap, and when dielectric liquids, such as Isopar or liquid developer, are present in the gap. In accordance with a preferred embodiment of the invention, means are provided for significantly reducing or eliminating electrical breakdown in the vicinity of the photoconductive surface 16, which breakdown could damage the photoconductive surface and/or the image. In this connection reference is made to Figs. 3A and 3B, which illustrate conceptually an intermediate transfer member 40 having a limited charged region or regions. Fig. 3A conceptually illustrates an intermediate transfer member 40 which is provided with an arrangement of electrical conductors whereby, at any given time, for any 1 given rotational st.ate of the intermediate transfer member, 2 only an angularly delimited portion of the intermediate 3 transfer member is energized to a sufficiently high voltage 4 as to define a significant potential difference relative to 5 the photoconductor surface 16. 6 In the illustrated embodiment, the energized portion, 7 indicated by a reference number 60, is delimited by 8 adjacent radii 61 and is selected so as to roughly 9 correspond with the region of the nip 62 between the 10 intermediate transfer member and the photoconductor surface 11. 16. According to one embodiment of the invention, the 12 energized portion corresponds to the region which is filled 13 with a liquid, thus substantially reducing or eliminating 14 electrical discharge thereat. According to a more 15 generalized concept of the invention, the energized portion 16 is not necessarily limited to the region filled with a 17 liquid but is limited to a region in which the gap does not 18 have a separation for which the breakdown voltage is less 19 than the potential difference between the energized portio 20 and the photoconductor surface 16, taking into account th 21 nature of the material disposed in the gap. Even mor 22 generally, small amounts of breakdown may be allowed. 23 In the embodiment of Fig. 3A a voltage differenc 24 across the gap of 1000V to 2000V should be maintained fo 25 best results, although lesser or greater voltage difference 26 may also be employed. 27 Fig. 3B illustrates a further development of th 28 structure illustrated in Fig. 3A. Here electrical voltage 29 are supplied to the conductors in the intermediate transfe 30 member 40 such that two different potentials are applied t 31 the surface of the intermediate transfer member in adjacen 32 regions 64 and 66, as illustrated. 33 This arrangement has particular utility in providing a 34 intermediate transfer member 40 which serves both t 35 rigidify the image prior to transfer and then to transfe 36 the rigidified image from the photoconductor surface 16 t 37 the intermediate transfer member 40. 38 In such an arrangement, where the pigmented particle are normally negatively charged, the image areas on the photoconductor surface positively charged, and the directions of rotation of the photoconductor surface 16 and of the intermediate transfer member 40 as indicated in Fig. 3B, portion 64 will be energized to a negative potential, typically -200V to -2000V, thereby to provide image compression or rigidization by urging the pigmented particles towards the image areas on the photoconductor surface, while portion 66 will be energized to a positive potential, typically +300V to +2500V, thus drawing the image electrophoretically from the photoconductor surface 16 through the solvent in the meniscus 68 onto the surface of intermediate transfer member 40 in region 66. The lower positive voltage on portion 66 can be used for a relatively high negative voltage on portion 64. One possible, but not definitive explanation of why good transfer is achieved with low positive voltage on portion 66 and high negative voltage on portion 64 is that charge transfer from the intermediate transfer member 40 to the photoconductive surface takes place, with consequent at least partial neutralization of the charge on the drum. Normally, portions 66 and 64 may be separated by a region on the photoconductor surface of intermediate potential, so as to prevent unwanted electrical discharge between portions 64 and 66. The outer boundaries of regions 64 and 66 are normally defined so as to avoid electrical breakdown between regions 64 and 66 and the photoconductor surface 16, as described above in connection with Fig. 3A. Reference is now made to Fig. 4, which is a signified and not necessarily to scale sectional illustration of an intermediate transfer member particularly useful in the apparatus shown in Fig. 2. The intermediate transfer member, generally indicated by reference numeral 70, typically comprises a high tensile strength substrate 72, such as Kapton, typically of thickness 10 microns, on which is preferably provided a resilient layer 74. A resistive heating layer 76, typically formed of nickel-chrome alloy, is preferably formed onto resilient layer 74 and is coupled to a source of electrical curren for providing desired heating of the intermediate transfe member 70 to assist in image transfer therefrom onto a image receiving substrate. Disposed over heating layer 76 is an insulative layer 78, typically formed of polyurethane o thickness 5 microns. Supported on insulative layer 78 is a generall parallel array 80 of generally uniformly spaced selectabl energizable electrical conductors 82. The elongate axes o the conductors 82 are generally perpendicular to th direction of movement, indicated by double headed arrow 84, of the intermediate transfer member 70 when in operation, a shown, for example, in Fig. 2. Conductors 82 are typically of thickness 35 microns an of width 500 microns and are separated by 250 microns. The are typically embedded in a layer 86 of thermally conductiv material, such as a silicone-polyurethane copolymer loade with 2% Degussa Printex XE-2, manufactured by Degussa AG o Frankfurt, West Germany, having a thickness about 10 microns over the conductors 82 and a resistivity of abou 10 +5 ohm-cm. Disposed over layer 86 is a release layer 88, such as Syl-Off manufactured by Dow Corning, having typical thickness of 10 microns. Reference is now made to Fig. 5, which illustrates a intermediate transfer member which is identical to tha shown in Fig. 4 except that the resistive heating layer 7 is not continuous but is rather formed of a generall parallel array 90 of generally uniformly spaced selectabl energizable electrical conductors 92. The elongate axes o the conductors 92 are generally perpendicular to th direction of movement, indicated by double headed arrow 84 of the intermediate transfer member 70 when in operation a shown, for example, in Fig. 2. The provision of array 90 instead of- a continuou resistive heating layer permits the heating of th intermediate transfer member 70 to be spatially selective for example, permitting heating of the intermediate transfe member only along that portion of its route which extend from the photoconductor surface 16 to the substrate 42 (Fi 2) . Heating of the image carried on the intermediat transfer member 70 along this portion of its route enable enhancement of the cohesiveness of the image to be realize without possible heat damage to the photoconductor surfac 16 as described in Assignee's copending U.S. Paten Application 272,323 filed November 21, 1988, the disclosur of which is incorporated herein by reference, and als permits heating of the image to be terminated with a desire level of precision to enhance transfer of the image from th intermediate transfer member to the substrate. Enhancemen of image transfer in this manner is described and claimed i Assignee's copending U.S. Patent Application filed Januar 4, 1989 and entitled: Method & Apparatus for Imaging Usin an Intermediate Transfer Member, the teaching of which i hereby incorporated herein by reference. This selective heating will be most effective if th heat capacity of the intermediate transfer member i relatively low, so that the heating and cooling can occur a described in the above-identified U.S. Patent Application. It will be appreciated that although the intermediat transfer members having one or more arrays of selectabl energizable conductors have been described and shown i Figs. 4 and 5 in the context of belts, the structure thereo may be applied equally to intermediate transfer members i the form of rollers, such as those employed in the apparatu of Fig. 1. In addition, some of the layers of the structure of Figs. 4 and 5 can be omitted, as may be desired if, fo example, heating is not desired. Reference is now made to Figs. 6 -10, which illustrat the use of selectably energizable conductors in rolle configurations. Figs. 6 and 7 illustrate an intermediat transfer member roller 40 having at least one array 80 o selectably energizable conductors in operative engagemen with a substrate 42 and a drum 10. An electrical energizin shoe 100 applies electrical power to the array 80. The sho 100 may comprise one or more brushes or contacts contactin one or more groups of conductors. Fig. 7 illustrates a preferred arrangement of the arra 80 on a roller 40. It is seen that the conductors 82 ar circumferentially offset adjacent the edge of the roller 40 The purpose of this offset is to enable energizing shoe 10 to be located outside of the nip between roller 40 and dru 10 yet nevertheless to apply a desired voltage to th conductors 82 located in the nip for enhancing transfe thereat while minimizing electrical breakdown as describe hereinabove. Fig. 8 illustrates an arrangement by which a sho assembly of the type illustrated in Fig. 10 may be mounte in tension in operative engagement with a roller 92. Th roller 92 is similar to roller 40, illustrated in Fig. 7 except that the conductors 82 are no longer required to b offset as shown in Fig. 7. The shoe assembly is held i tensioned contact with roller 92 and contacts 112, 114 an 116 of a shoe 110 (Fig. 10) are in contact with th extremities of conductors 82. The diameter of drum 10 i reduced at a region facing the extremities of conductors 82 as shown in Fig. 9, to provide clearance of shoe 110. Accordingly, as seen in Fig. 10, contact 112 may b maintained at -2000 Volts, contact 114 may be maintained a 0 Volts and contact 116 may be maintained at +500 Volts An electrical connector 120, shown in Fig. 8, may provid the desired voltages to respective connectors 122, 124 an 126 which are electrically coupled to shoe portions 112, 11 and 116 respectively. It may be appreciated that an intermediate transf member of the type illustrated in Fig. 5, having two arra 80 and 90 of conductors, may receive electrical power v shoe assemblies 110 arranged at opposite ends of the roll 92, as illustrated in Fig. 9. Reference is now made to Fig. 11, which illustrat electrophotographic imaging apparatus generally similar that shown in Fig. 1 with the following principal exceptio the use of an intermediate transfer member is abandoned favor of direct transfer from the photoconductor surface to a substrate 130, such as paper. The direct transfer i effected by the provision of guide rollers 132, 134 and 136, which guide a continuous web of substrate 130, and a driv roller 138, which cooperates with a support web 140. suitable charging device, as a corona discharge device 142, charges the substrat at a transfer location, for effecting electrophoreti transfer of the image from the photoconductor surface 16 t the substrate 130. According to a preferred embodiment of the invention, the apparatus of Figs. 1 or 11 may be constructed and operative with a rigidizing roller 30 (Fig. 1, 11-13) . As shown in Figs. 12-13, roller 30 includes a generally parallel array 150 of generally uniformly spaced selectably energizable electrical conductors 152. The elongate axes of the conductors 152 are generally perpendicular to the direction of movement of the rigidizing roller 30 in operation as shown, for example, in Fig. 12, wherein the motion of the rigidizing roller is indicated by an arrow 154. Conductors 152 are typically of thickness 35 microns and of width 500 microns and are separated by 250 microns. There is defined a general region 155 between the rigidizing roller 30 and the photoconductor surface 16, delimited by imaginary radii 156, in which the chance of electrical breakdown is low due to the presence thereat of a meniscus of the dielectric toner carrier. In this region, conductors 152 are charged to a voltage opposite to the polarity of that of the pigmented toner particles, typically -500 to -2000 Volts. This arrangement compresses the toner particles of the image, thus rigidizing the image on the photoconductor surface, for resulting enhancement of transfer therefrom. It should be understood that the roller 30 of Fig. 12 can also act as a squeegee roller, substantially removing most of the liquid from the image and further physically compressing the image. Fig. 13 illustrates a further development of the apparatus of Fig. 12 in which roller 30 serves as a metering, background removal and rigidizing roller. In this arrangement, two regions 160 and 162 are defined and opposite voltages are applied to the conductors 152 in those regions, much in the same way as described above and illustrated in Fig. 3B. This arrangement has particular utility in providing a background removal and rigidifying roller 30 which serves both to remove background from the image and to rigidify the image prior to transfer. In such an arrangement, where the pigmented particles are normally negatively charged and the image areas on the photoconductor surface are positively charged, and the directions of rotation of the photoconductor surface 16 and of the roller 30 which is spaced from surface 16, are as indicated in Fig. 13, region 160 will be energized to a positive potential, typically +200 Volts, thereby to draw pigmented particles away from the background areas of the photoconductor surface 16. Region 162 will be energized to a negative potential, typically -200V to -2000V, thereby t provide image rigidization by urging the pigmented particle towards the image areas on the photoconductor surface. Normally, between regions 160 and 162 there may be region on the roller 30 of intermediate potential, so as t prevent unwanted electrical discharge between regions 16 and 162. The outer boundary of region 162 will normally b defined so as to avoid electrical breakdown between regio 162 and the photoconductor surface 16. Metering of excess liquid from the photoconductiv surface 16 is achieved by counter rotation of roller 30 in direction indicated by an arrow 164, as is well known in th art. Reference is now made to Fig. 14 which illustrate electrophotographic imaging apparatus which is substantiall similar to that illustrated in Fig. 11 with the followin exception; roller 30 is replaced by a non-rotatin rigidizing element 170 having an electrically charged regio 172 which is located interiorly of the edges of element 170 such that electrical breakdown is prevented. Region 172 is selected such that the gap separatio between the element 170 and the photoconductor surface 16 i such that when the gap is filled with dielectric tone carrier liquid during operation, no electrical discharg takes place at the operating voltages, which are preferabl in the range of -200 to -2000 Volts for the element 17 within region 172, when the photoconductor surface 16 i charged to 1000 Volts at the image region and 50 Volts a the background region. The rigidizing element is preferabl hydrodynamically shaped so that rotation of the roller wil cause it to be spaced about 15 microns from the surface o the photoconductor, when it is lightly urged towards th photoconductor. Alternatively it may be kept at a fixe spacing from the photoconductor of the order of 50 microns. Alternatively, a larger portion of the element 170 ca be electrified, and the upstream end to the element shape to provide a- meniscus of insulating carrier liquid, until the spacing in air between the element 170 and th photoconductor are large enough to prevent breakdown o corona. It will be appreciated that the signs of the variou voltages have been given for an example using negatively charged toner particles. The invention is equally applicable to the use of positively charged toner particles with a negatively charged photoconductor, appropriate changes being made in the signs of the stated voltages. It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow:

Claims: C L I M S 1. Apparatus for enhancement of liquid toner image transfer comprising: an image bearing surface; means for forming a liquid toner image on said imag bearing surface; a second surface arranged for movement relative to sai image bearing surface whereby regions of the image bearing surface and the second surface sequentially come int propinquity and subsequently move out of propinquity; potential impression means associated with at least on portion of at least one of the image bearing surface and th second surface for impressing a potential on said at leas one portion; and means for energizing said potential impression mean only when said at least one portion are located a predetermined locations along the pathway, thereby t provide image rigidization. 2. Apparatus according to claim 1 wherein: said potential impression means comprises a pluralit of electrical conductors associated with at least one of th image bearing surface and the second surface. 3. Apparatus for image transfer comprising: an image bearing surface; an image compacting surface arranged for operativ engagement with the image bearing surface and having forme therein at least one electrical conductor; and means for energizing the at least one electrica conductor at a location interior with respect to th engagement of the image compacting surface and the imag bearing surface whereby a relatively high voltage differenc may be developed between the image compacting surface an the image bearing surface. 4. Apparatus according to claim 1 wherein sai liquid toner image comprises image regions and backgroun regions, said apparatus comprising: means for removing pigmented toner particles from th background regions defined on the image bearing surface; an squeegee means for removing excess liquid from sai liquid image after rigidization thereof, prior to transfe of said image to a substrate. 5. Apparatus according to claim 1 wherein: said toner image comprises charged toner particles; said second surface is the surface of a roller an moves opposite to said image bearing surface; and said potential impression means comprises means fo impressing upon a first region on said second surface first potential to provide background cleaning and fo impressing upon a second region of said second surface second potential of the same polarity as the polarity o said toner particles providing rigidization of said liqui toner image on said image bearing surface. 6. Apparatus according to claim 2 and als comprising means for energizing the electrical conductors, thereby to provide a desired electrical field at a desire location for producing image rigidization thereat. 7. Apparatus according to claim 1 and wherein sai second surface comprises a rotatable surface. 8. Apparatus according to claim 3 and wherein sai second surface comprises a static surface relative to whic the image bearing surface moves. 9. Apparatus according to any of claims 1, 2 or 8 and comprising: an intermediate transfer member for receiving sai liquid toner image from said image bearing surface afte rigidization thereof, for transfer of said image to substrate. 1 10. Apparatus according to claim 8 wherein sai 2 liquid toner image comprises image regions and backgroun 3 regions, said apparatus comprising: 4 means for removing pigmented toner particles from th 5 background regions defined on the image bearing surface; an 6 squeegee means for removing excess liquid from sai 7 liquid image after rigidization thereof, prior to transfe 8 of said image to a substrate. 9 10 11. Apparatus according to claim 8 and wherei 11 energization of the at least one electrical conducto 12 provides a desired electrical field at a desired locatio 13 for producing image rigidization. . 14 15 12. Apparatus according to any of claims 4 or 1 16 and comprising: 17 an intermediate transfer member for receiving sai 18 toner image from said image bearing surface afte 19 rigidization thereof, for transfer of said image to 20 substrate. - 21 22 13. Apparatus according to claim 2 wherein sai 23 liquid toner image on said image bearing surface comprise 24 image regions and background regions, said apparatu 25 comprising: 26 means for removing pigmented toner particles from th 27 background regions defined on the image bearing surface; an 28 squeegee means for removing excess liquid from sai 29 liquid toner image after rigidization thereof, prior t 30 transfer of said image to a substrate. 31 32 14. Apparatus according to claim 2 and wherein: 33 said toner image comprises charged toner particles; 34 said second surface is the surface of a roller an 35 moves in a direction opposite to the direction of moveme 36 of said image bearing surface; and 37 said potential impression means comprises means fo 38 impressing on at least one of said plurality of conductors a first potential of a polarity opposite to the polarity o said toner particles to provide background cleaning and fo impressing upon a second conductor associated with at leas one of said plurality of conductors, a second potential o the same polarity as the polarity.of said toner particle providing rigidization of said liquid toner image on sai image bearing surface. 15. Apparatus according to either claim 1, 5 o 14 and wherein said second surface is the surface of a roller and said surface moves in a direction opposite to the direction of movement of said image bearing surface thereby providing metering of excess liquid on said image bearing surface. 16. Apparatus according to claim 8 wherein said operative engagement comprises an entrance region, an exit region and a third region therebetween, and wherein said energizing means is associated only with said third region. 17. Apparatus according to claim 5 wherein said first potential is of a polarity opposite to the polarity of said toner particles. 18. Apparatus for image transfer comprising: an image bearing surface arranged to support a liquid toner image, comprising image regions and background regions thereon; means for rigidizing said toner image at said image regions; and an intermediate transfer member for receiving said toner image from said image bearing surface after rigidization thereof, for transfer of said image to a substrate. 19. Apparatus according to claim 18 and comprising: squeegee means for removing excess liquid from said toner image after rigidization thereof, prior to transfer o said image to said intermediate transfer member. 20. Apparatus according to claim 18 and als comprising means for removing excess liquid from the imag bearing surface. 21. Apparatus according to claim 18 wherein: said means for rigidizing comprises a rigidizing rolle maintained at a potential opposite to the potential of imag areas of the image bearing surface and which does no contact the image; and said apparatus also comprises: means for removing pigmented toner particles from sai background regions; and means for removing excess liquid from the image bearin surface. 22. Apparatus according to claim 18 wherein sai means for rigidizing comprises: a second surface arranged for motion relative to th image bearing surface along a pathway whereby portions o the image bearing surface and the second surfac sequentially come into propinquity and subsequently move ou of propinquity; potential impression means associated with at least on portion of at least one of the image bearing surface and th second surface for impressing a potential on said at leas one portion; and means for energizing said potential impression mean only when said at least one portion is located at predetermined location along the pathway, thereby to provid image rigidization. 23. Apparatus according to claim 22 wherein: said potential impression means comprises a pluralit of electrical conductors associated with at least one of th image bearing surface and the second surface. 24. Apparatus according to claim 22 wherein sai second surface is arranged for operative engagement with th image bearing surface and has formed therein at least on electrical conductor; and wherein said apparatus als comprises: means for energizing the at least one electrica conductor at an interior location with respect to th engagement of the second surface and the image bearin surface whereby a relatively high voltage difference may b developed between said interior location of said secon surface and the image bearing surface. 25. Apparatus according to claim 22 and wherei said potential impression means comprises means fo impressing a first portion of said second surface with first potential of a first polarity and simultaneousl impressing a second portion of said second surface with second potential of a second polarity. 26. Apparatus according to claim 25 and wherein toner image formed of pigmented particles having a charge o said second polarity is provided on the image bearin surface, and wherein said first potential on said firs portion provides background cleaning and said secon potential on said second portion provides rigidization of said toner image on said image bearing surface. 27. Apparatus according to claim 26 and wherein said second surface is the surface of a roller and said surface moves in a direction opposite to the direction of movement of said image bearing surface thereby providing metering of excess liquid on said image bearing surface. 28. Apparatus according to claim 26 and wherein said second surface is the surface of a roller and said surface moves oppositely to the movement of said image bearing surface. 29. Apparatus according to claim 23 and wherein energization of the electrical conductors provides a desired electrical field at a desired location for producing image rigidization. 30. Apparatus according to claim 18 and wherein said means for rigidizing comprises a rotatable surface which operatively engages said image. 31. Apparatus according to claim 18 and wherein said means for rigidizing comprises a static surface relative to which the image bearing surface moves. 32. Apparatus according to claim 31 and wherein said static surface comprises at least one electrical conductor and wherein energization of said at least one electrical conductor provides a desired electrical field at a precise location for producing image rigidization. 33. Apparatus according to claim 18 wherein said means for rigidizing comprises a squeegee roller maintained at a potential opposite to the potential of image areas of the image bearing surface and which simultaneously compacts the image and removes excess liquid from the image. 34. Apparatus for image transfer comprising: an image bearing surface arranged to support a liquid toner image comprising image regions and backgroun regions thereon; means for rigidizing said liquid toner image a said image regions comprising: a member having an elastic outer layer havin at least one ply of elastic material whose outer surface i arranged for movement relative to the image bearing surfac along a pathway whereby regions of the image bearing surfac and the outer surface sequentially come into propinquity an subsequently move out of propinquity; and potential impression means contained withi at least one portion of said elastic outer layer fo impressing a potential on said at least one portion whe said at least one portion is in propinquity with said imag bearing surface to apply a potential therebetween; and an intermediate transfer member for receiving sai toner image from said image bearing surface afte rigidization thereof, for transfer of said image to substrate. 35. A method for imaging comprising the steps of: forming a liquid toner image on an image bearing surface; rigidizing said liquid toner image; transferring said rigidized image to an intermediate transfer member; and subsequently transferring said image to a final substrate. 36. Apparatus according to claim 34 wherein said at least one ply of elastic material comprises at least two plies and wherein said potential impression means is positioned between said two plies. 37. Apparatus according to claim 32 wherein said static surface engages said image bearing surface in an entrance region, an exit region and a third region therebetween, and wherein said energizing means is associated only with said third region. 38. Apparatus according to claim 1, 2, 4 or 22-29, wherein said propinquity includes touching engagement. 39. Apparatus according to any of claims l, 2, 4 or 22-29, wherein said propinquity does not include touching engagement. 40. Apparatus according to claim 24 wherein said second surface is a static surface relative to .which the image bearing surface moves. 41. Apparatus for image transfer comprising: an image bearing surface arranged to support a liqui toner image thereon, comprising image regions and backgroun regions; rigidizing means for rigidizing said toner image a said image regions; and squeegee means separate from said rigidizing means fo removing excess liquid from said toner image afte rigidization thereof, prior to transfer of said image to substrate. 42. Apparatus according to claim 41 wherein sai liquid toner image comprises charged toner particles an wherein said apparatus also comprises: means for removing pigmented toner particles fro the background regions a background cleaning roller; an wherein said rigidizing means comprises a rigidizing rolle maintained at a potential having a polarity opposite to th polarity of said charge on said charge toner particles. 43. Apparatus according to claim 41 wherein sai rigidizing means comprises: a second surface arranged for movement relative to sai image bearing surface along a pathway whereby portions o the image bearing surface and of the second surfac sequentially come into propinquity and subsequently move ou of propinquity; potential impression means associated with at least on portion of at least one of the image bearing surface and th second surface for impressing a potential on said at leas one portion; and means for energizing said potential impression mean only when said at least one portion is located at predetermined location along the pathway, thereby to provid image rigidization. 44. Apparatus according to claim 43 wherein sai potential impression means comprises a plurality o electrical conductors associated with at least one of th image bearing surface and the second surface. 45. Apparatus according to claim 41 wherein sai rigidizing means comprises: an image compacting surface arranged for operative engagement with the image bearing surface, the image compacting surface having formed thereon at least one electrical conductor; and means for energizing the at least one electrical conductor at an interior location with respect to the engagement of the image compacting surface and the image bearing surface whereby a relatively high voltage difference may be developed between the image compacting surface and the image bearing surface. 46. Apparatus according to claim 43 and wherein said potential impression means comprises means for impressing a first potential of a first polarity onto a first portion of said second surface and for simultaneously impressing a second potential of a second polarity onto a second portion of said second surface. 47. Apparatus according to claim 46 and wherein a liquid toner image formed of pigmented particles having a charge of said second polarity is provided onto the image bearing surface, and wherein said first potential on said first portion provides background cleaning and said second potential on said second portion provides rigidization of said toner image on said image bearing surface. 48. Apparatus according to claim 43 and wherein said second surface is the surface of a roller and said second surface moves in a direction opposite to the direction of movement of said image bearing surface thereby providing metering of excess liquid on said image bearing surface. 49. Apparatus according to claim 44 and wherei energization of the electrical conductors provides a desire electrical field at a desired location for producing imag rigidization. 50. Apparatus according to claim 41 and wherei said rigidizing means comprises a rotatable surface. 51. Apparatus according to claim 41 and wherei said image compacting surface comprises a static surfac relative to which the image bearing surface moves. 52. Apparatus according to claim 47 and wherei said second surface is the surface of a roller and sai second surface moves in a direction opposite to th direction of movement of said image bearing surface thereb providing metering of excess liquid on said image bearin surface. 53. Apparatus according to any one of claims 41 45, 46 or 48 and comprising: an intermediate transfer member for receiving a tone image from said image bearing surface after rigidizatio thereof, for transfer of said image to a substrate. 54. Apparatus according to claim 51 wherein sai operative engagement comprises an entrance region, an exi region and a third region therebetween and wherein sai energizing means is associated only with said third region. 55. Apparatus for image transfer comprising: an image bearing surface and an image receiving membe comprising an elastic outer layer having at least one ply o elastic material defining an outer image receiving surfac arranged for relative movement along a pathway whereb regions of the image bearing surface and the image receivin surface sequentially come into propinquity for imag transfer therebetween and subsequently move out o propinquity following image transfer therebetween; potential impression means contained within at least one portion of said elastic outer layer for impressing a potential between said at least one portion and said image bearing surface; and means for energizing said potential impression means only when said at least one portion is located at a predetermined location along said pathway, thereby to provide image transfer enhancement. 56. Apparatus according to claim 55 wherein said potential impression means comprises a plurality of electrical conductors. 57. Apparatus according to claim 55 wherein said potential impression means comprises means for impressing a potential of a first polarity opposite to the polarity of the charge on the image particles. 58. Apparatus according to claim 55 wherein said potential impression means comprises means for impressing a first potential on said at least one portion when said at least one portion is located at a first predetermined location and for impressing a second potential on said at least one portion when said at least one portion is located at a second predetermined location adjacent said first predetermined location. 59. Apparatus according to claim 55 and wherein said potential impression means comprises means for simultaneously impressing a first potential on a first portion of said at least one surface and a second potential on a second portion of said at least one surface adjacent said first portion. 60. Apparatus according to claim 55 and wherein said potential impression means comprises means for impressing a first potential on a first portion of said a least one surface when said first portion is located at first predetermined location and for impressing a seco potential on said first portion when said first portion i located at a second predetermined location adjacent sai first predetermined location, and for simultaneousl impressing said second potential on said second portion whe it is located at said second predetermined location and sai first potential on said second portion when it is located a said first location. 61. Apparatus according to claim 55 and wherei said potential impression means comprises: means for simultaneously impressing a first potentia on a first portion of said at least one surface when sai first portion is located at a first predetermined locatio and a second potential on a second portion of said at leas one surface when said second portion is located at a secon predetermined location; and means for simultaneously impressing said secon potential on said first portion when said first portion i located at said second predetermined location and said firs potential on a third portion when it is located at sai first location. 62. Apparatus according to any one of claims 59 60 or 61 and wherein said first and second potentials are o opposite polarities. 63. Apparatus according to claim 56 and wherei said plurality of electrical conductors comprise first an second arrays of electrical conductors arranged on sai image receiving surface and said means for electricall energizing comprise: first means for selectably energizing at least on electrical conductor of said first array for providing desired potential at a first predetermined location; and second means for selectably energizing at least on electrical conductor of said second array for providin desired heating of said image receiving surface at a secon predetermined location. 64. Apparatus according to claim 55 and als comprising means for removing excess liquid from the imag bearing surface. 65. Apparatus according to claim 55 and wherei said potential impression means provides a desire electrical field at a desired location for producin electrophoretic image transfer thereat. 66. Apparatus according to claim 63 and wherei said apparatus also comprises means for subsequentl transferring said image from said image receiving member an wherein energization of said at least one conductor of sai second array provides desired resistance heating of th image prior to said subsequent transfer. 67. Apparatus according to claim 63 wherei said image bearing surface is arranged to support a liqui toner image thereon, comprising image regions and background regions, said apparatus comprising: means for removing pigmented toner particles from the background regions defined on the image bearing surface. 68. Apparatus according to claim 67 wherein said means for removing comprises a roller with a potential intermediate the potentials of the image regions and the background regions. 69. Apparatus according to claim 56 wherein said potential impression means comprises means for impressing a potential of a first polarity, the same as that of the polarity of the charge on the image particles, on at least one conductor in a first region and for impressing a potential of a second polarity, opposite to that of the 1 polarity of the charge on the image particles, on at leas 2 one conductor in a second region adjacent said first region 3 to provide image transfer to said image receiving member at 4 said first region and image rigidization at said second 5. region. 6 7 70. Apparatus according to claim 69 and wherein 8 said plurality of electrical conductors comprises first and 9 second arrays of electrical conductors arranged on said 0 image receiving surface and said means for electrically 1 energizing comprise: 2 first means for selectably energizing at least one 3 electrical conductor of said first array for providing a 4 desired potential at a first given location on said image 5 receiving surface; and 6 second means for selectably energizing at least one 7 electrical conductor of said second array for providing 8 desired heating of said image receiving surface at a second 9 given location. 0 1 71. Apparatus according to claim 55 and also 2 comprising second transfer means for image transfer from 3 said image receiving surface to a substrate. 4 5 72. Apparatus for image transfer comprising: 6 an image bearing surface and an image receiving 7 surface arranged for relative movement along a pathway 8 whereby regions of the image bearing surface and the image 9 receiving surface sequentially come into propinquity for 0 image transfer therebetween and subsequently move out of 1 propinquity following image transfer therebetween; 2 potential impression means associated with a 3 least one portion of at least one of the image bearin 4 surface and the image receiving surface for simultaneousl 5 impressing a first potential on a first portion of said a 6 least one surface and a second potential on an adjacen 7 second portion of said at least one surface; and 8 means for energizing said potential impressio means to impress said first potential only when said firs portion is located at a predetermined location along sai pathway, thereby to provide desired image transfe enhancement along said first portion and simultaneous imag rigidization along said adjacent second portion. 73. Apparatus for image transfer of a liquid tone image comprising: an image bearing surface, adapted to carry sai liquid toner image and electrically insulating carrie liquid thereon; an image receiving surface arranged for relativ movement along a pathway whereby regions of the imag bearing surface and the image receiving surface sequentiall come into propinquity at an image transfer region for imag transfer therebetween and subsequently move out o propinquity following image transfer therebetween, wherei said liquid toner image and carrier liquid fill a firs section of the region between said image bearing and imag receiving surfaces; potential impression means associated with at least on portion of at least one of the image bearing surface and th image receiving surface for impressing a potential on sai at least one portion; and means for energizing said potential impression means when said at least one portion is located completely withi said first section. 74. Apparatus according to claim 55 wherein said at least one ply of elastic material comprises at least two plies of elastic material and wherein said potential impression means is located between said two plies. 75. Apparatus for image transfer comprising: an image bearing surface; an image receiving member comprising an outer layer defining an outer image receiving surface, arranged for relative movement along a pathway whereby regions of the image receiving surface and the image bearing surface come into propinquity for image transfer therebetween and subsequently move out of propinquity following image transfer therebetween; electrical potential impression means contained within said outer layer comprising a plurality of electrical conductors; means for energizing said electrical potential impression means to provide improved image transfer from said image bearing surface to said image receiving surface; and means for subsequently transferring said image to a final substrate. 76. Apparatus according to claim 75 wherein said plurality of electrical conductors comprise first and second arrays of electrical conductors and said means fo energizing comprises: first means for energizing at least one electrical conductor of said first array for providing a desire potential at a first predetermined location; and second means for energizing at least one conductor o said second array for providing desired heating of sai image receiving surface. 77. Apparatus for transferring an image comprising: an image bearing surface; an image receiving member comprising an outer laye defining an outer image receiving surface, arranged fo relative movement along a pathway whereby regions of th image receiving surface and the image bearing surface com into propinquity for image transfer therebetween and subsequently move out of propinquity following imag transfer therebetween; potential impression means associated with one of sai image bearing and image receiving surfaces fo simultaneously impressing a first potential on a firs portion of said at least one surface and a second . potentia on an adjacent second portion of said at least one surface and means for energizing said potential impression means t impress said first potential only when said first portion i located at a predetermined location along said pathway, t provide desired image transfer enhancement along said firs portion and simultaneous image rigidization along sai adjacent second portion. 78. Apparatus according to claim 77 wherein sai outer layer comprises an elastic outer layer having at leas one ply of elastic material. 79. Apparatus according to claim 77 wherein sai potential impression means is contained within said oute layer. 80. Apparatus according to claim 77 wherein sai potential impression means comprises a plurality o electrical conductors. 81. Apparatus according to claim 77 and wherein sai first and second potentials are of opposite polarities. 82. Apparatus according to claim 77 wherein said image bearing surface is arranged to support a liquid tone image thereon, comprising image regions and backgroun regions, said apparatus comprising: means for removing pigmented toner particles from th background regions defined on the image bearing surface. 83. Apparatus according to claim 77 wherein sai image is a liquid toner image comprising carrier liquid an charged toner particles and wherein said first potential is of the same sign as the sign of the toner particles and sai second potential is of opposite sign to that of the tone particles. 84. Apparatus according to claim 77 and also comprising second transfer means for image transfer from said image receiving surface to a substrate. 85. Apparatus according to claim 78 wherein said at least one ply of elastic material comprises at least two plies of elastic material and wherein said potential impression means is positioned between said two plies. 86. Apparatus according to any one of claims 55, 72, 73, 75 or 77, wherein said propinquity includes touching engagement.

Inventors: ADAM YOSSI, FENSTER PAUL, KRUMBERG YAKOV, LANDA BENZION, LAVON AMIRAN, PINHAS HANNA, ADAM, YOSSI, FENSTER, PAUL, KRUMBERG, YAKOV, LANDA, BENZION, LAVON, AMIRAN, PINHAS, HANNA
Applicants: SPECTRUM SCIENCES BV, SPECTRUM SCIENCES B.V.
Application year: 1990
Main classification: G03G15
IPC codes: G03G5, G03G15