Imaging system
United States Patent 1191 Harris et al.  
 [ Apr. 22, 1975 IMAGING SYSTEM 175] Inventors: Jerome N. Harris, Webster; Sanford G. Hoffman; John C. Witte, both of Rochester, all of NY.  
 [73] Assignee: Xerox Corporation, Stamford,  
 Conn.  
 [22] Filed: July 26, 1973 21 Appl. No.: 382,786  
 [52] US. Cl. 118/637; 117/37 LE; 1l8/DIG. 23 [51] Int. Cl G03g 13/00 [58] Field of Search 118/D1G. 23, 637, 429&#39;,  
 117/37 LE, 94.3 A  
 [56] References Cited UNITED STATES PATENTS 3,162.104 12/1964 Medley ll8/DlG. 23  
 3.411.482 11/1968 Brodie 1l8/DlG. 23  
 3,540 409 11/1970 Lloyd 118/6 3611992 10/1971 Lyles 118/637 3.664.298 5/1972 Giaimo, Jr. 118/637 3.749.059 7/1973 Sato 118/637 3.753.706 8/1973 Sankus. Jr. et a1 96/1 R 3.758.204 9/1973 Mochizuki 355/10 Primary E.\aminerMervin Stein Assistant Examiner-Leo Millstein Attorney, Agent, or FirmJames J. Ralabate; David C. Petre; Ronald L. Lyons [57] ABSTRACT A liquid meniscus developing system for continuously and rapidly developing latently imaged migration imaging members, substantially free of background material is disclosed.  
 41 Claims, 18 Drawing Figures IMAGING SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to migration imaging systems and more specifically to methods and apparatuses for liquid meniscus developing migration imaging members.  
  A migration imaging system capable of producing high quality images of high density. continuous tone and high resolution has been developed. Such imaging systems are disclosed in copending applications Ser. No. 837,780 and Ser. No. 837,591. both filed June 30. 1969. In a typical embodiment of these migration imaging systems, an imaging member comprising a substrate, a layer of softenable material and electrically photosensitive marking material is latently imaged, e.g., by electrically charging the member and exposing the charged member to a pattern of activating electromagnetic radiation, such as light. Where the photosensitive migration material is originally in the form of a fracturable layer at the upper surface of the softenable material, particles of the migration material in the exposed areas of the imaging member migrate toward the substrate when the member is developed by decreasing the resistance of the softenable layer sufficient to allow migration of the migration material in depth in the softenable material.  
  Various methods for developing the latent images in migration imaging systems are known. These development methods include solvent wash-away; solvent vapors softening. heat softening and combinations of these methods, as well as other methods of the migration material to allow the migration material to migrate in depth in the softenable material in imagewise configuration. In the solvent wash-away development method, migration material migrates in imagewise configuration in depth in the softenable layer as the softenable layer is softened and dissolved, leaving an image of migrated particles corresponding to the desired image pattern on a substrate, with the softenable layer and unmigrated migration material substantially completely washed away.  
  There are various systems for forming migration imaging members, wherein non-photosensitive or photosensitively inert, migration material are arranged in fracturable layers, or dispersed throughout the softenable layer in a binder configuration, as described in the aforementioned copending applications, which also disclose a variety of methods which may be used to form latent images upon such migration imaging members.  
  Various methods and material and combinations thereof have Previously been used to fix the unfixed migration images. For example, fixing methods and mate-- rials are disclosed in copending applications Ser. No. 590,959, filed Oct. 31. 1966, now abandoned and Ser. No. 695,214, filed Jan. 2, 1968, now U.S. Pat. No.  
  Copending application Ser. No. 300,940, filed Oct. 26, 1972, states that typical migration imaging members (the same type members used in the instant application) may be liquid meniscus developed at speeds of about to 3 inches per second although the system is capable of higher speed operation. 7  
  The instant invention, is an improvement upon the basic concept of liquid meniscus development as disclosed in copending application Ser. No. 300,940, filed Oct. 26, 1972. Several patentably distinguishable improvements over this prior art are disclosed. The results of these patentably distinguishable improvements enable migration imaging members to be developed substantially free of background particles at much higher speeds than was previously possible by use of the prior art teachings. The instant invention disclosed liquid meniscus apparatuses which are capable of operating easily at motion picture speeds, i.e., at least 4 inches per second with optimum operating speeds of about 7 inches per second. The above speeds are obtainable due to several advancements in the art, the most important being l the critical positioning in a meniscus support member of a liquid development supply aperature, (2) the use of an electrode for removing unmigrated migration material in the meniscus support member and (3) the ability to position the liquid support member in various angular positions with relationship to the horizontal plane in order to allow the entrance edge of the development surface of the meniscus support member to be located below the aperture.  
  The above mentioned higher speeds are very important when one desires to use migration imaging members in a combination apparatus comprising a camer/processor/projector at motion picture speeds, i.e., at least 4 inches per second with substantially no background on the developed member. The maximum speed before the instant invention utilizing known processes would not allow speeds above about 2 inches per second without allowing unacceptable material. to exit on the developed member and remain on the member. Therefore, it is an object of this invention to overcome the limitation of the prior art and to provide a system for rapidly developing migration imaging members substantially free of background material.  
 SUMMARY OF THE INVENTION It is an object of this invention to provide a system for the rapid development, i.e., motion picture speed, of latently imaged migration imaging members by liquid meniscus development.  
  It is another object of this invention to provide a system for development of latently imaged migration imaging members at a speed of at least 4 inches per second while providing developed images of the same or higher quality than former developed migration images.  
  It is another object of this invention to locate, in some embodiments, at least one aperture in specific locations on the development surface of the meniscus support member to prevent predevelopment of the latently imaged migration imaging members by solventvapor development.  
  It is another object of this invention to provide a system for removing unmigrated migration material, i.e., background material, from imaged migration imaging members by the use of a specifically located electrode in the development surface of the meniscus support member.  
  It is another object of this invention to locate an aperture for supplying development liquid in the development surface of a meniscus support member in a position in relationship to the entrance edge of the development surface so as to allow rapid development of a latently imaged migration imaging member.  
 It is another object of this invention to provide a system for the development of latently imaged migration imaging members using a minimum amount of liquid developer.  
  The foregoing objects and others are accomplished in accordance with this invention by a system wherein a migration imaging member typically comprising migration material contained in or contacting a layer of softenable material having a latent image formed thereon is rapidly developed by an apparatus comprising a meniscus support member with a surface adapted to receive a migration imaging member comprising a base having a development surface spaced adjacent and parallel to the longitudinal path of a migration imaging member. The development surface has a concave cross-section and at least one aperture whereby development liquid may be supplied to the development surface. In a particular embodiment. the aperture for supplying development liquid is located sufficiently close to the exit edge of the development surface to prevent residual material, i.e.. unmigrated migration material, from exiting on a migration imaged member. In this embodiment the entrance edge of the development surface is located below the aperture which supplies development liquid whereby development liquid entering the development surface through the aperture flows over the imaged member and down the development surface toward the entrance edge of the development surface. This allows the residual softenable material and unmigrated migration material to be washed clear of the imaged member before the imaged member exits the apparatus thereby allowing rapid development substantially free of background material. Alternately, another embodiment disclosed for rapidly developing migration imaging members substantially free of background material comprises a meniscus support member with a surface adapted to receive migration imaging members comprising a base having a development surface having a concave cross-section and at least one aperture through which development liquid may be supplied to the development surface of the meniscus support member. The aperture is located sufficiently close to the entrance edge of the development surface to prevent premature development by solvent/vapor development of the migration imaging member. The development surface further contains an electrode which biases the path of the imaging member whereby unmigrated migration material may be removed from a developed imaging member. The electrode is positioned along the path of the imaging member preferably after the aperture. The position of the electrode must be such that when it biases the member. it will not interfere with development of the latently imaged member, i.e.. migration of the migration material. This develop ment occurs after the member enters the entrance meniscus of the development liquid. The development zone is normally located between the entrance meniscus ofthe development surface of the meniscus support member and the aperture which supplies development liquid to the development surface. However. the development zone may be located directly above the entrance edge or the aperture.  
 DESCRIPTION OF THE DRAWINGS For a better understanding of the invention as well as other objects and further features thereof, reference is made to the following detailed disclosure of preferred embodiments of the invention taken in conjunction with the accompanying drawings thereof. wherein:  
  FIGS. llu. lb, It and Id are partially schematic. crosssectional views of migration imaging members suitable for use in the instant invention.  
  FIGS. 2a and 2b illustrate typical processes used for latently imaging typical migration imaging members for use in the instant invention.  
  FIG. 20 illustrates in partially schematic, a crosssectional view of an imaged member.  
  FIGS. 2:! and 2e illustrate in partially schematic. cross-sectional views of embodiments of the development system of the instant invention, these embodiments invetion. particularly suited for rapidly and continuously developing latently imaged migration imaging members.  
  FIG. 2f illustrates in partially schematic, a crosssectional view of an imaged member, developed and fixed in the inventive system.  
  FIG. 3a illustrates in partially schematic. a crosssectional view of a meniscus development apparatus illustrating a meniscus support member containing a aperture for supplying development liquid to the development surface and an electrode for removing unmigrated migration material. The roller is shown as merely a means of providing a migration imaging member in the path adjacent the mensicus support member.  
  FIG. 3b illustrates in partially schematic. a crosssectional view of a meniscus support member containing an aperture for supplying development liquid and an electrode for removing residual material and a stationary means for providing a migration imaging member in the path spaced adjacent to the development surface of the meniscus support member.  
  FIG. 30 illustrates in partially schematic, a crosssectional view of the meniscus development system of the present invention illustrating further the meniscus support member containing an aperture and an electrode.  
  FIG. 31! illustrates in partially schematic, a crosssectional view of the meniscus development system of the present invention illustrating the angle at which the aperature is positioned in relationship to the development surface. Also shown is an electrode located on the development surface of the meniscus support member.  
  FIG. 4a illustrates in partially schematic. a crosssectional view of still another embodiment of the instant invention illustrating a meniscus support member with the entrance edge to the development surface of the meniscus support member below an aperture for supplying development liquid for the migration imaging member. The development liquid enters the development surface through the aperture, flows down and over the development surface and imaged member toward the entrance edge. Further shown is a roller as a means for providing migration imaging members in the path spaced adjacent to the development surface of the meniscus support member.  
  FIG. 4b illustrates in partially schematic. a crosssectional view of still another embodiment of the development system of the present invention wherein a meniscus support member contains an aperture for supplying development liquids to the development surface. The entrance edge of the development surface is lo cated below the aperture whereby development liquid entering the development surface through the aperture flows down and over the development surface and imaged member toward the entrance edge. Further illu trated is a stationary means for providing a migration imaging member in the path adjacent said development surface of said meniscus support member.  
  FIGS. 4c and 4e illustrate in partially schematic, cross-sectional views of meniscus support members with apertures for supplying development liquids to the development surface of the meniscus support members.  
 DESCRlPTlON OF THE PREFERRED EMBODIMENT In FIG. la, a migration imaging member preferred for use in the advantageous system of the present invention is illustrated in a partially schematic, crosssectional view wherein the imaging member 4 comprises a supporting substrate 5 supporting a layer of softenable material 2 and a fracturable layer comprising migration material 1. Migration imaging members of this type may be referred to as the layer configuration migration imaging member, and such members are fully described in copending application Ser. No. 837,780, filed June 30, 1969, the entire disclosure of which is hereby incorporated by reference herein.  
  Supporting substrate 5 may be in various embodiments of such migration imaging members either electrically conductive or electrically insulating, or even partially electrically conductive. The electrically insulating substrate materials will typically have resistivities of not less than about ohm-cm., and resistivities preferably not less than about l0 ohm-cm. However, materials having lower resistivities will perform satisfactorily in various embodiments hereof. The supporting substrate 5 is prefereably partially or substantially translucent or transparent where the imaging member is to be viewed with transmitted light. In some embodiments, substrate 5 may comprise a more electrically insulating material, and have a more electrically conductive material coated thereon at the surface 3, so&#39;that the coated substrate functions as an electrically conductive substrate.  
  The layer of softenable material 2 may comprise one or more layers of any suitable material which is capable of having its resistance to migration of migration material reduced sufficiently to allow migration of the migration material in depth in the softenable material. The softenable material 2 is typically substantially electrically insulating for the preferred modes hereof of applying electrical migration forces to the migration layer, although, more conductive material may be used because of the increased capability in the electrical mode hereof of applying a constant and replenishing supply of electrical charges in image configuration In still other embodiments, the softenable material may itself be electrically photosensitive or photoconductive; such softenable materials and imaging systems utilizing such materials are fully described in copending application Ser. No. 837,592, filed June 30, 1969, the entire disclosure of which is incorporated by reference herein.  
  Softenable&#34; as used herein with reference to the material of layer 2, is intended to mean any material which may have its resistance to migration reduced sufficiently to allow migration of the migration material 1. Furthermore, it is intended to mean any material which can be rendered more permeable to the migration of the migration material through its bulk. Conventionally, changing permeability of such material or reducing its resistance to migration of migration material,  
 may be accomplished, for example, by dissolving, melting or softening.  
  Typically preferred substantially electrically insulating softenable material includes a host of plastic or thermoplastic materials, examples of which are specifically recited in copending application Ser. No. 837,780; paraffms and waxes, and any other material which is typically substantially electrically insulating, and capable of having its resistance to migration reduced sufficiently to allow migration of the migration material may be used in the advantageous system of the present invention. Such substantially insulating softenable materials will typically have resisitivities not less than about 10 ohm-cm, and preferably have resisitivities of not less than about 10 ohm-cm. However, in various embodiments of the inventive imaging system. softenable materials with even lower resistivities will perform satisfactorily.  
  Softenable layer 2 may be of any suitable thickness, with thicker layers generally requiring greater electrical potentials. Softenable layer thicknesses from about /2 to about 16 microns are found to be preferred, but uniform thickness over the imaging area in the range between about 1 and about 4 microns is found to provide high quality images while permitting readily image member construction.  
  Fracturable&#34; layer or material as used herein, means any layer or material which is capable of breaking up during development, thereby permitting portions of said layer to migrate toward the substrate or to be otherwise removed. The fracturable layer may be particulate, semi-continuous, microscopically discontinuous or continuous in various embodiments of the migration imaging member of the present invention. such fracturable layers of marking material are typically contiguous the surface of the softenable layer and contacting the softenable layer and spaced apart from the substrate, and such fracturable layer may be near. or coated onto or slightly or partially or substantially embedded in the softenable layer in the various embodiments of the imaging members of the inventive system. contiguous for the purpose of this invention, is defined as in Websters Collegiate Dictionary, Second Edition, 1960; in actual contact; touching; also, near though not in contact; adjoining, and is intended to generally describe the relationship of the fracturable layer of marking material in the softenable layer vis-avis the surface of the softenable layer spaced apart from the substrate.  
  The migration material 1 illustrated in a fracturable layer in FIG. la, may comprise any suitable materials selected from an extremely broad group of materials and mixtures thereof including electrically conductive materials. insulating materials, partially electrically conductive materials, electrically photosensitive materials, photosensitively inert materials, or any other material having any other suitable physical characteristics. A host of such suitable materials are described in copending application Ser. No. 837,780, filed June 30, 1969. ln FIG. la the migration material 1 is arranged in a fracturable layer contacting the softenable layer 2 and contiguous the surface of the softenable layer 2 spaced apart from the substrate 5, portions of which migrate towards or to the substrate 5 during image formation under the influence of migration forces. It is preferred for images of highest resolution. density and utility that the fracturable layer of migration material I be a particulate material layer; however. such fracturable layers may also comprise any continuous or semicontinuous. or microscroptically discontinuous fracturable layer. which is capable of breaking up into discrete particles of the size of an image element or less during the development step. thereby permitting portions of the fracturable layer to migrate toward the substrate in image configuration. As described in the incorporated disclosures. particles of the migration material suitable for use in the present invention are preferably of average size not greater than about 2 microns. Submicron particles give an even more satisfactory result. with an optimum range of particle size comprising particles of average size of not greater than about 0.7 microns. When the migration material is arranged in a fracturable layer contacting the softenable material spaced apart from the substrate, such fracturable layers are preferably of thickness in the range from about 0.01 to about 2.0 microns. althrough fracturable layers of thickness of about 5.0 microns have been found to give good results in various embodiments.  
  Migration material used in the present invention will typically be suitably insoluble and otherwise not adversely reactive with either the softenable material or any other element in the imaging member. as well as any solvent liquid which may be used in the development step in the present invention.  
  FIG. lb. illustrates binder type configuration migration imaging member wherein the migration material I is dispersed throughout the layer of softenable material 2 which is supported by substrate 5. Such binder-type imaging members as well as materials and methods for their construction is fully described in copending application Ser. No. 837.590. filed June 30. I969. the entire disclosure of which is hereby incorporated by reference herein. Substrate 5, softenable material 2 and migration material I. used in the binder-type imaging member are the same as or similar to those suitable for use in the layer configuration migration imaging member described above in conjunction with FIG. la.  
  In FIG. 10. another embodiment of the migration imaging member suitable for use in the instant invention is illustrated wherein the first softenable layer 2b. which is typically free or void of migration material is overcoated on substrate 5, and then a second softenable layer 2a having a fracturable layer of migration material 1 contacting the softenable layer 2a and the surface of said second softenable layer 20 opposite the surface thereof nearest the substrate 5, overcoats the first softenable layer 2b. In this migration imaging member. two separate softenable layers facilitate the fabrication of the member in that a first softenable layer may be applied to a suitable substrate and then a second softenable layer, containing the migration material 1 may be coated over the first softenable layer.  
  In FIG. It] still another embodiment of the migration imaging member suitable for use in the present invention is illustrated wherein the substrate supports a first layer 2b. which is typically substantially void or free of migration material. and a second layer 26 over coating the first layer 2b. and the second softenable layer 20, having migration material I dispersed throughout the softenable material. In such an embodiment as well as in the embodiment illustrated in FIG. 1c. it may be advantageous to use two different softenable materials in the softenable layer and 2b wherein the softenable material used in the second layer 2c. ex-  
 hibits greater solubility or greater speed of solubility in the liquid solvents or other media being used in advantageous systems of the present invention. Any suitable combination of the softenable material suitable for use herein may be used in such embodiments. For example. an imaging member having a first softenable layer comprising polystyrene of molecular weight of about 10.000. over-coated with a second softenable layer comprising polybutylmethacrylate. may be developed with petroleum ether. which differentially softens the two softenable layers. Similarly, the imaging member having a softenable layer comprising a customsynthesized about /20 mole percent copolymer of styrene-hexlmethacrylate overcoated with a softenable layer comprising Nirex polyterpene resin. available from Tenneco Chemicals Inc., Newport Division. may be developed in Sohio Odorless Solvent 3440. a kerosene fraction available from Standard Oil Company of Ohio. Other suitable combinations may be found amoung the materials listed in applications Ser. Nos. 837,789, and 837.591, as well as in Ser. No. 27.890. filed Apr. 13. I970. the entire disclosure of which is hereby incorporated by reference herein.  
  FIGS. 20 and 2b illustrated in partially schematic. cross-sectional views. process steps typically used in the advantageous system of the present invention. Although the imaging members used in the illustration of FIG. 2a and 2b are similar to the imaging members illustrated and described in conjunction with FIG. la. it should be understood that any of the migration imaging members described herein, or any other suitable migration imaging members, may be used in the advanta geous system of the present invention. The basic steps of the migration imaging system. as clearly described in copending application Ser. No. 837.780 and Ser. No. 837.591. as referenced herein. generally comprise providing a migration imaging member. applying an imagewise migration force to the migration imaging member. and developing the member by reducing the resistance of the softenable material to migration of the migration material sufficient to allow imagewise migration of the migration material at least in depth in the softenable material toward the substrate.  
  One of the preferred methods of applying an imagewise migration force to the migration material is to provide an electrically latent image on the migration imaging member. Various methods of providing electrical latent images and electrostatic latent images are described in the aforementioned copending applications. A particularly preferred method of providing electrically latent images is the optimum charged-exposed mode wherein the migration imaging member comprising an electrically photosensitive material. which when substantially uniformly electrically charged and image wise exposed with activating electromagnetic radiation. forms an electrical latent image corresponding to the image exposure. Upon development, the migration material, which is typically particulate material, migrates in imagewise configuration and in image densities proportional to the charge densities in the electrical latent image. or when the charge-expose mode is used, proportional to the amount of exposure to activating electromagnetic radiation. In this way. continuous tone (or half-tone) migration images result from the migration imaging system.  
  The term electrical latent image&#34; is used to described the latent image in the advantageous system of the present invention. and that term and the several variant forms thereof used herein include the images formed by the charge-expose mode. which images cannot readily be detected by standard electromagnetic techniques as an electrostatic latent image. for example. of the type found in xerography may be so that no readily detectable or at best a small change in the elcctrostatic potential is found after exposure (when using preferred exposure levels); and include electrostatic latent images of the type similar to those found in xerography which are typically readily measurable by standard electrometers. that is electrostatic latent images showing surface potentials typically reading at least from about to volts.  
  FIGS. 2a and 2b illustrate the optimum chargeexpose mode of forming an electrical latent image on an imaging member. In FIG. 2a the migration imaging member comprises substrate 5 having conductive coating 3 thereon. supports softenable layer 2 having a fracturable layer of migration material 1 contacting the softenable layer 2 and contiguous the surface of the softenable layer 2 opposite the substrate 5. This member is illustrated as being electrically grounded 7 and electrically charged with an electrical charging device such as a cortron charging device 6. which passes adjacent the surface of the imaging member. In FIG. 2b. the charged imaging member is shown being imagewise exposed to activating electromagnetic radiation in areas 8. Upon imagewise exposure. the electrically photosensitive material of the present invention apparently undergoes a selective relocation of charge into or within or out of the material. said relocation being effected by the activating electromagnetic radiation acting on the bulk or surface of the electrically photosensitive material. This may specifically include photoconductive effects, photoinjection. photoemission, photochemical effects and others which enhance or cause selective relocation of charge in the electrically photosensitive material.  
  After the imagewise migration force is applied or even during its application. here in the form of an electrical latent image on the imaging member. the latently imaged member is developed by reducing the resistance of the softenable material to migration of the migration material sufficient to allow migration of the migration material in depth in the softenable material or by changing the permeability of the softenable material. In the aforementioned copending applications. developing has typically meant changing the permeability or reducing the resistance of the softenable material to migration of the migration material, for example, by use of liquid solvents which may in one embodiment of development soften the softenable material sufficient toallow migration of the migration material or may include other embodiments which include wash-away development by dissolving the softening layer. or by other means such as solvent. solvent vapors, heat or combination thereof. as well as others. which reduce the resistance of the softenable material to migration of the migration material to allow migration of the migration material in depth in the softenable material in situ.  
  FIG. illustrates a developed migration imaging member. The imaging member used in the illustration of FIG. 20 is similar to the imaging member illustrated and described in conjunction with FIG. la. However. it should be understood that any of the migration imaging members described herein or any other similar migration imaging members may be used in the instant invention resulting in similar developed members. In FIG. 21&#39; the migration imaging member. comprising substrate 5 having conductive coating 3 thereon which supports softenable layer 2 having unmigrated migration material 1 contacting the softenable layer 2 and contiguous the surface of softenable layer 2 opposite the substrate. The member is illustrated by having migration material la which has migrated in imagewise configuration to substrate 5 in the imagewise exposed areas.  
  In FIG. 2a the development step is illustrated wherein the migration imaging member 4 supporting an electrical latent image is developed by contacting the latently imaged migration imaging member 4 with a developing liquid capable of reducing the resistance of the softenable material to migration of the migration material. In the embodiment of the instant invention illustated in FIG. 2d the volume of development liquid is bounded by two meniscuses. i.e.. entrance meniscus 33 and exit meniscus 34. In this embodiment. the volume of development liquid is supplied to the volume of development liquid bounded by the two meniscuses 33 and 34 by at least one passageway 15 through meniscus support member l3. Passageway 15 carries development liquid to aperture 14 located in development surface I8. Aperture 14 is located sufficiently close to the entrance edge 12 of development surface 18 to prevent solventvapor development of a migration imaging member prior to the liquid meniscus development.  
  The development surface 18 also contains an electrode 19 which biases the path of the imaging member 4 whereby residual material. i.e.. unmigrated migration material lb. may be removed from a developed imaging member. Electrode 19 is positioned along the path of the imaging member 4 in development surface 18 after aperture 14 and before the exit edge 11.  
  In this embodiment. the volume of developing liquid is minimized and the meniscus is made small or controlled. by the small spacing between the meniscus support member 13 and the imaging member 4. As the latently imaged member 4 passes into the volume of development liquid through entrance meniscus 33. the softenable material of layer 2 is softened and/or dissolved thereby decreasing the resistance of the softenable material to migration of the migration material allowing imagewise migration of the migration material toward the substrate. The migration material la is shown in FIG. 2d as having migrated in imagewise configuration to substrate 5. The unmigrated migration particles lb and portions of the softenable layer 2 are dissolved and/or washed away in the volume of solvent development liquid bounded by meniscuses 33 and 34. The surface tension forces and the relative movement of the imaging member to the liquid casues the residual materials to be caught up in the development liquid and removed from the image member before the member passes through and out of the exiting meniscus 34. However. if the speed of the migration imaging member through the meniscus developing apparatus. i.e.. processing speed. is greater than that for which solvent contact time allows for sufficient dissolution of the softenable layer to remove unmigrated particles. the unmigrated migration material lb is also carried out or allowed to pass through and out of exiting meniscus 34 on the imaged member causing excess background material. i.e.. unmigrated migration material. remaining ill on the member. This undersirable condition was alleviated by the use of electrode 19 which biases the path of the imaging member after migration has occured whereby residual material, i.e., unmigrated migration material, is removed from the developed imaging member thereby preventing background material from pass ing through and out of exiting meniscus 34 on the imaged member. The ummigrated migration particles lb along with residual softenable material from layer 2 are removed from the electrode area by gravity flow. Therefore, the developing liquid containing residual softenable material and unmigrated migration material lb may flow over the sides of the liquid meniscus sup port member 13 and into a residual reservoir 17 or there may be an aperture and passageway in and through the meniscus support member for removing the residual material.  
  The use of electrode 19 in FIG. 2d allows migration imaging members to be processed through the meniscus developing apparatus. i.e., processing speed, at  
 speeds of at least 4 inches per second. using a 4 inch meniscus support member free of background, whereas meniscus developing apparatuses which do not contain the above described electrode could achieve only about 2 inches per second or in most cases, less, free of background, when using a 4 inch meniscus support member.  
  Depending upon the development solvent-softenable material combination. the softenable layer may in various embodiments have its resistance to migration reduced sufficiently to allow migration of the migration material in depth in the softenablematerial toward the substrate and allow the electrode I9 to remove the unmigrated migration material leaving the softenable layer 2 substantially intacted in its original configuration or only partially removed or substantially completely removed, leaving only the migrated migration marking material on the substrate.  
  It should be appreciated that in the embodiment where the material of the softenable layer 2 is left intacted upon the substrate 5, or is only partially removed, that the image member comprises a fixed migration image wherein the imagewise migration material is overcoated by the remaining softenable material, and is thereby protected from external destructive forces such as scratching, abrading, smudging, etc., which would ordinarily degrade or destroy an unfixed image comprising migrated migration material on the substrate without a fixative overcoating. In addition. where an even greater degree of fixing is desired, the above-described fixed imaged member may be further overcoated more easily because the particles of migration material are already at least partially fixed to the substrate.  
  In FIG. 20 the development step illustrated therein illustrates an imaging member 4 supporting an electrical latent image wherein development is illustrated by contacting the latently imaged member 4 with a developing liquid capable of reducing the resistance of the softenable material 2 to migration of the migration material l sufficiently to allow migration of the migration material I in depth in said softenable material II. In the embodiment of the present invention illustrated in FIG. 20, the volume developing liquid is bounded by two meniscus, i.e., entrance meniscus 33 and exiting meniscus 34. In this embodiment, the volume of development liquid is supplied through at least one passageway 311 through meniscus support member 26. Passageway ill containes an aperture 27 which is located in the surface of development surface 28. Aperture 27 is further located sufficiently close to the exit edge 30 of the development surface 28 to prevent residual material, i.e., unmigrated migration material llb from exiting on an imaged migration imaging member. The entrance edge 29 of the meniscus support member 26 is located below the aperture 27 so that the development liquid entering development surface 28 through aperture 27 flows down and over the development surface 28 toward entrance edge 39. In this embodiment the volume of de velopment liquid is minimized and the meniscus is made small and/or controlled by the small spacing between the support member 26 and the imaging member 4 and the rate at which the development liquid is supplied. As the latently imaged member 4 passes into the volume of development liquid through entrance meniscus 33, the softenable material 2 is softenable and/or dissolved thereby decreasing the resistance of the softenable material to migration of the migration material sufficiently to allow migration of the migration material in depth in said softenable material toward the sub strate 5. The unmigrated migration material lb and residual softenable material from softenable layer 2 are washed away in the volume of development liquid. The surface tension forces and relative movement of the imaging member in the development liquid causes these residual materials to be caught up in the development liquid and removed from the imaged member as it continues to pass through and out of the exiting meniscus 34. However, if the speed of the member is more than about 2 or 3 inches per second, all of the unmigrated migration material will not be removed from the imaged member as it continues to pass through and out of exiting meniscus 34 thereby leaving background mate rial on the image member. This background material left on the image member is certainly undesirable. This problem was overcome by advancing liquid support member 26 around in imaginary circle so that entrance edge 29 of liquid meniscus support member 26 is located below aperture 27 so that development liquid entering the development surface 28 through aperture 27 will flow down and over development surface 28 towards entrance edge 29. As the volume of development solvent containing residual softenable material from softenable layer 2 and unmigrated migration material Rb becomes larger at or near the entrance edge 29 the liquid may flow over entrance edge 29 into residual material reservoir 17. However, an aperture and passageway may be located near entrance edge 29 through which the residual material may exit the meniscus support member into reservoir 17. The system as illustrated in FIG. 20 allows migration imaging members to be developed at relatively high speeds, i.e., at least 4 inches per second or greater, free of background material, i.e., unmigrated migration material.  
  Depending upon the development solvent/softenable material combination, the speed of movement of the imaging member through the meniscus development liquid, the exposure time ofthe member to the development solvent and various other conditions, the softenable layer may be partially removed or substantially completely removed leaving only the migrated marking material on the substrate.  
  It will be appreciated that where the material of the softenable material is only partially removed, that the image member comprises a fixed migration image wherein the imagewise migration material is overcoated by the remaining softenable material, and is thereby protected by external destructive forces such as mentioned above.  
 FIG. 2f illustrates a member imaged and developed by the method illustrated in FIGS. 211-20. FIG. 2f  
 clearly shows that the imaged member comprises substrate having thereon migrated migration material In which has migrated to substrate 5 in image configuration and the remaining portion of the softenable material 2. FIG. 2f further illustrates that the upper portion of the softenable layer 2, as well as the unmigrated migration material 1b, are removed. This removal was described in conjunction with FIGS. 2d and 20.  
  Although in the descriptions in conjunction with FIGS. 2a-2f of the instant migration imaging system have been primarily directed to an embodiment wherein the imaging member is latently imaged by an electrically latent image, the inventive meniscus development system may be used to develop migration imaging members which have been latently imaged by an suitable means. Any of the methods oflatently imaging such a member as described in the incorporated disclosures of copending applications Ser. No. 837.780 and Ser. No. 837,591 are suitable for use in the instant system. However, this development must be prior to the member passing over electrode 19 as shown in FIG. 2d. Indeed, any means of selectively providing an imagewise migration force, i.e., latently imaging, such a migration imaging member is intended to be encompassed within the scope of the present invention.  
  Imaging members which have already been completely imaged by the migration-type imaging process which have migration material in a migrated image configuration and additionally in a background configuration. wherein the migrated image configuration-is at least in part spaced apart in depth in the softenable layer from the background configuration may be used in the present invention.  
  FIG. 3a illustrates a liquid meniscus developing apparatus which in conjunction with the description of FIG. 2d illustrates a system for continuously developing migration imaging members at relatively rapid rates, e.g., at least 4 inches per second. free of background material comprising a liquid meniscus support member 13 which has a development surface 18 adapted to receive a migration imaging member. The meniscus support member 13 comprises a base 36 having a development surface 18 which is spaced adjacent and parallel to the longitudinal path of migration imaging member 4. The development surface 18 has a surface which is concave cross-section. Preferably the concave cross-section is extended through an are from about to about 125 on an inside radius from about 1.5 inches to about 8.0 inches of said are. Development surface 18 has both an entrance edge 12 and an exit edge 11. Development surface 18 has at least one aperture 14 which is located sufficiently close to the entrance edge 12 of the development surface 18 to prevent pre-development by solvent-vapor of a latently imaged migration imaging member. Solvent-vapor development comprises generally the exposure of a migration imaging member to solvent vapors which reduce the resistance of the softenable material to migration of the migration material sufficiently to allow migration of the migration material in depth in the softenable material. However, in the instant invention, it has been found that if solvent-vapor development occurs prior to liquid meniscus development. that complete migration of the migration particles to the substrate or at least migration sufficient to form an image may not occur when the member is liquid meniscus developed after it has been subjected to solvent vapors. Therefore, a criticality of the instant invention is that aperture 14 supplying the development liquids to development surface 18 be located sufficiently close to entrance edge 12 of development surface l8 to prevent solvent-vapor development. Furthermore, it is preferred that aperture 14, when it enters the development surface 18, enter at an angle towards entrance edge 12 of from about 20 to about in relationship to the development surface 18. Aperture 14 is also preferably located a distance from the entrance edge 12 of development surface 18 of from about 1.0 percent to about 30.0 percent of the total length of development surface 18. Aperture 14 is more preferably located a distance from the entrance edge 12 of development surface 18 of from about 1.0 percent to about 25.0 percent of the total length of the development surface 18. It should be understood that development surface 18 may be supplied development liquid through a plurality of apertures and passageways in meniscus support member 13. Furthermore. these apertures and especially aperture 14 is supplied through passageway 15 by supply line 16 which connects to any suitable means such as a pump or reservoir for supplying development liquid to development surface 18.  
  As mentioned earlier. it is desirable to continuously replenish the development liquid in the meniscusbound region in order to keep the concentration of the dissolved softenable material and unmigrated marking materials in the developing liquid at minimum levels so that the unmigrated migration material will not exit from the meniscus development area on the imaged member but will because of gravitational forces flow towards the center of gravity of the meniscus support member and flow out and over the side of the meniscus support member and into a residual reservoir 17 shown in FIG. 3a. However, an aperture and passageway may be located in meniscus support member 18 near the center of gravity of the meniscus support member for removing the residual materials.  
  Furthermore, development surface 18 contains an electrode 19 which biases the path of imaging member 4 in order to remove unmigrated migration material from the developed imaging member. The positioning of this electrode 19 is preferably along the path of the member after aperture 14 in order that the electrical field created by the electrode across the member will not interfere with development of the latently image migration imaging member, i.e., imagewise migration of the migration material toward the substrate. Furthermore, electrode 19 should normally be located before exit edge 11 of development surface 18. Electrode 19 is preferably located a distance from exit edge 11 of development surface 18 of from about 1.0 percent to about 50 percent of the totallength of development surface 18. Electrode I9 is more preferably located a distance from the exit edge 11 of development surface 18 of from about 25 percent to about 45 percent of the total length of development surface 18.  
  It should be appreciated that the imaging member support member 10 may be a free wheeling roller rotating about an axis 9 in FIG. 3a or may be a drive roller and may comprise any suitable configuration including. for example. a bar. plate. sheet. drive sprocket or any other desired configuration in various embodiments. When the imaging member contains electrical conductive layer 3 as shown in FIG. la and lb. it should be understood that the imaging member may be biased or electrically grounded by an suitable means which may include an electrical grounding or biasing means other than support member 10. However. when support member 10 is used as an electrical biasing or grounding means then support member 10 must be conductive and may be of any suitable electrically conductive material.  
  Electrode 19 in development surface I8 may be in a circuit with a potential difference 23 whereby electrode I9 and support member 10 may be oppositely biased thereby creating an electrical field across the softenable layer and migration material in an area between the imaging member and meniscus support member where development of the imaging member has already occurred. i.e.. normally after aperture 14 on development surface 18. Furthermore. it should be understood that electrode 19 may be in a circuit with a potential difference whereby electrode 19 and conductive layer 3 shown in FIGS. la and lb may be oppositely biased by utilizing any means for electrically biasing or electrically ground conductive layer 3 other than by utilizing roller 10. Any suitable means may be used to contact conductive layer 3 in order to place an electrical field across the member between conductive layer 3 and electrode 19. When roller 10 is not utilized in electrically biasing or electrically grounding -the imaging member and electrode 19, then roller 10 may be of any suitable material whether conductive or nonconductive.  
  The electrical field is being placed across the member after it has been developed in order to remove unmigrated migration material from the imaged member prior to the imaging member exiting the menisucs support member exiting edge 11. The location of the aperture 14 in relationship to the electrode 19 in the development surface 18 enables the instant apparatus to operate at much greater speeds than was possible in the prior art since the prior art did not teach background removal by use of specifically located electrodes Processing speeds may be at least 4 inches per second. This enables the instant apparatus to be utilized in a much large system wherein it is desired to operate a combination. camera/processor/projector, at continuous motion picture speeds of about 7 inches per second. e.g.. 16mm film moving at 24 frames per second. free of background material.  
  Roller 21 rotating about axis 21a and roller 20 rotating about axis 20a are merely illustrative ofa means of supplying a migration imaging member to the liquid meniscus developer and a means for storing the developed migration imaged member.  
  Migration imaging members may be advanced in the path between the meniscus support member 13 and the support member 10 by any suitable means. A flexible member may be used. Furthermore, this flexible member may be an endless belt.  
  The preferred spacing between the meniscus support member 13 and the imaging member. is in the range of between 1 mil and about 15 mils. The meniscus support member is close enough to the surface of the imaging member to create agitation and turbulence in the development liquid near the meniscus.  
  The spacing between the two supporting members. i.e.. the liquid meniscus support member 13 and the imaging member support member 10 of FIG. 311 between which an imaging member is passed is typically from about 2 mils to about 25 mils. More preferably. the dis tance is from about 6 mils to about 15 mils.  
  The width of development surface 18 should be the same width as the area on the migration imaging memher to be developed. However. it is preferred that when the entire development surface of the imaging member is to be developed that the width of development surface 18 of meniscus support member 13 should not be wider than the area to be developed on the imaging member. If the width of development surface 18 is wider than the total development area of the imaging member, then the development liquid containing residual softenable material and unmigrated migration material will be allowed to get into sprocket drive holes in the edge of the imaging member if the member is being sprocket driven. Also. the development liquid containing the above mentioned residual material. i.e.. unmigrated migration material and residual softenable material. tends to creep around the edges of the member and get on the back of the member making storage and usage of the member difficult.  
  An important factor in liquid meniscus development is the solvent contact time with the migration imaging member. i.e.. the time that the migration imaging mem ber is in surface contact with the development liquid.  
  It should be understood that the solvent contact time is a function of the softenable material and the development solvent used.  
  The liquid meniscus support member 13 shown in FIG. 3a may be of any length depending upon the speed at which one desires to operate the apparatus. For example. a 4 inch long development surface would allow imaging members to be processed at a rate of 4 inches per second with a solvent contact time of one second which is sufficient to obtain optimum migration images substantially free of background material utilizing the instant process. With a development surface 24 inches long one could process imaging members at a speed of 24 inches per second and still achieve a solvent contact time of I second. Preferably. the length of development surface 18 between entrance l2 and exit edge 11 along the surface of development surface 18 is from about 1 to about 30 inches. More preferably, this length is from about 3 to 5 inches.  
  The apparatus illustrated in FIG. 3a may additionally comprise a meniscus across the path bounding at least in part a volume of liquid capable of developing a migration imaging member. the meniscus bounded at least in part by development surface 18 of meniscus support member 13 and the means for providing a migration imaging member in the path adjacent development surface 18 of meniscus support member 13.  
  FIG. 3b illustrates still another embodiment of the instant invention which is illustrated in FIG. 3a with the exception that FIG. 3b contains support member 22 which is a stationary support member.  
  FIG. 3c is a isometric view of liquid mensicus support member 13 from FIG. 3a which illustrates preferable locations of aperture 14 and electrode 19 in development surface 18 of liquid support member 13. Aperture I4 and electrode 19 are shown in the face of the development surface 18. Development surface 18 is typically adjacent and parallel to the imaging materials. i.e.. softenable material and migration material in the imaging members during the process of the present invention.  
  Electrode 19 illustrated in FIG. 30 and also in FIGS. 2:! and 3u-3d must obviously be isolated. i.e.. electrically insulated. from meniscus support member I3 when the meniscus support member 13 may be of a non-conductive material. However. the meniscus support member 13 may be of a non-conductive material. Therefore as mentioned earlier. electrode 19 is located in a position on development surface 18 of liquid meniscus support member 13 so that electrode I9 will not interfere wtih the meniscus development. i.e.. imagewise migration of migration material. of a latently imaged migration imaging member which is developed when the member enters the entrance meniscus 33 shown in FIG. 2d. The development process. i.e.. migration of the migration material in the softenable material in imagewise configuration. is almost instantaneously as compared to the speed of the film moving through the processor. Therefore. electrode 19 may be located relatively close to aperture 14 in FIG. 2d and still not interfere with development.  
  FIG. Sr! is a cross-sectional schematic view of liquid meniscus support member 13. Aperture I4 is shown entering development surface I8 toward the entrance edge I2 at an angle to the development surface of about 45. It is preferred that aperture 14 enter development surface I8 at an angle toward entrance edge 12 of from about 20 to about 90 in relationship to development surface 18. Also shown is electrode 19 located in the surface of development surface I8 positioned along the path of an imaging member and after the aperture I4 and before the exit edge 11 of the development surface 18.  
  FIG. 4a illustrates still another embodiment of an apparatus of the instant invention which utilizes liquid meniscus development as further illustrated in the system described in conjunction with FIG. 2a. In FIG. 4a a liquid meniscus support member 26 is shown comprising a base 37 having a development surface 28 spaced adjacent and parallel to the longitudinal path of a migration imaging member. The development surface 28 has a concave cross-section. The concave crosssection is preferably extended through an are from about to about 125 on an inside radius of from about 1.5 inches to about 8.0 inches on said are. Development surface 28 may be the same type surface as shown in FIG. 3a as development surface 18. The development surface 28 has both an entrance edge 29 and an exit edge 30. The development surface 28 also has at least one aperture 27 which supplies development liquid to development surface 28. The location of aperture 27 is critical. in that. aperture 27 should be located sufficiently close to the exit edge 30 of development surface 28 to prevent residual material. i.e.. unmigrated migration material. from exiting on imaged migration imaging members. Location of aperture 27 is also critical. in that. the entrance edge 29 of development surface 28 must be located below aperture 27 so that development liquid entering development surface 28 through the aperture 27 flows down and over development surface 28 towards entrance edge 29.  
  Aperture 27 preferably should be located a distance from about 1.0 percent to about 30.0 percent of the total length of development surface 28 from exit edge 30 of development surface 28. More preferably. aperture 27 is located a distance of from about 5 percent to about 25 percent of the total length of development surface 28 from exit edge 30 of development surface 28. It should be understood that development surface 28 may be supplied development liquid through a plurality of apertures and passageways in meniscus support member 28. Furthermore. these apertures and especially aperture 27 is supplied through passageway 31 by supply line 16 which connects to any suitable development liquid supply means. e.g.. a pump or reservoir.  
  As mentioned earlier. it is desirable to continuously replenish the development liquid in the meniscusbound region in order to keep the concentration of the dissolved softenable material and unmigrated marking materials in the developing liquid at minimum levels so that the unmigrated migration material will not exit from the meniscus development area on the imaged member but will. because of gravitational forces. flow down the development surface 28 and flow out and over entrance edge 27 and into a residual reservoir 17 shown in FIG. 4a.  
  It should be understood that an aperture and passageway may be located in meniscus support member 26 near the center of gravity of the meniscus support member for removing the residual materials.  
  An imaging member support means is illustrated as a free wheeling roller 35 which rotates on axis 9 which is used for providing a migration imaging member in the path spaced adjacent to development surface 28 of meniscus support member 26.  
  Imaging member support 35 for providing a migration imaging member in the path spaced adjacent development surface 28 is from about 2 mils to about 25 mils in distance from development surface 28. More preferable this distance is from about 6 mils to about 15 mils from development surface 28.  
  It should be realized that any suitable configuration may be used as imaging member support 35. Roller 35 may be of the same type and configuration as shown in FIG. 3a and described therewith as roller 10.  
  The width of development surface 28 of meniscus support member 26 should be the same width as the area of the migration imaging member to be developed. However. it is preferred that when the entire development surface of the imaging member is to be developed that the width of development surface 28 of meniscus support member 26 should not be wider than the area to be developed on the imaging member. If the width of development surface 28 is wider than the total development area of the imaging member. then the development liquid containing residual softenable material and unmigrated migration material will be allowed to get into sprocket drive holes in the edge of the imaging member if the member is being sprocket driven. Also. the development liquid containing the above mentioned residual materials. i.e.. unmigrated migration material and residual softenable material. tends to creep around the edges of the member and get on the back of the member making storage and usage of the member difficult.  
  The discussion of the length of development surface 18 in FIG. 3a applies to the length of development surface 28 in FIG. 4a. Perferably the length of development surface 28 between entrance edge 29 and exiting edge 30 is from about 1 to about 30 inches. More preferably. this length is from about 3 to about 5 inches.  
  The spacing between the liquid meniscus support 26 and the imaging member support member 35 between which an imaging member is passed is typically about 2 mils to about 25 mils. More preferably, this distance is from about 6 mils to about mils.  
  The center of meniscus support member 26, i.e., a imaginary point equal distance from entrance edge 29 and exit edge 30 on development surface 28 on meniscus support member 26, is capable of being advanced about an imaginary circle up to about 90 on either side of an imaginary radius of the circle which is perpendicular to the horizontal plane. The circumference of the circle is coincidental with an arc of the concave crosssection of development surface 28 of meniscus support member 26. Meniscus support member 26 is advanced along the circumference of the circle sufficiently to allow entrance edge 29 to be located below aperture 27 whereby development liquid entering the development surface 28 will flow down and over development surface 28 toward and over entrance edge 29 into residual reservoir 17. As mentioned, there may be at least one exit aperture and passageway in meniscus support member 26 sufficiently close to entrance edge 29 for removing development liquid containing residual mate rials.  
  Residual reservoir I7 may be located below the entrance edge 29 of the development surface 28 or below an exit aperture and passageway positioned to receive unmigrated migration material and residual softenable material and excess development solvent as more clearly shown in the method as illustrated in FIG. 20. Rollers 21 and serve the same general function as described in FIG. 3a.  
  Migration imaging members may be advanced in the path between the meniscus support member 26 and the imaging member support 35 by any suitable means. A flexible member may be used. Furthermore, this flexible member may be an endless belt.  
  Development surface 28 may additionally contain an electrode 36 shown in FIG. 40 which may bias the path of an imaging member in order to remove unmigrated migration material from the developed imaging member in the embodiment described in conjunction with FIGS. 2e and Ia-4t in the same manner as electrode 19 shown in FIGS. 2d and 3a-3d. The positioning of electrode 36 is preferably along the path of the member and in a position such that the electrical field created by electrode 36 across the member will not interfere with development of the imaging member, i.e., imagewise migration of the migration material toward the substrate. Furthermore, electrode 36 should normally be located before exit edge of development surface 28. Electrode 36 is preferably located a distance from the exit edge 30 of development surface 28 of from about 1.0 percent to about 70 percent of the total length of development surface 28. Electrode 36 is more preferably located a distance from the exit edge 30 of development surface 28 of from about 1.0 percent to about 50 percent of the total length of development surface 28.  
  The apparatus illustrated in FIG. 4a may additionally comprise a meniscus across the path bounding at least in part a volume of liquid capable of developing a migration imaging member the meniscus bounded at least in part by development surface 28 of meniscus support member 26 and the means for providing a migration imaging member in the path adjacent development surface 28 of meniscus support member 26.  
  FIG. 4b is essentially the same configuration as shown in FIG. 4a with the exception that the imaging member support means 32 is shown as a stationary support.  
  FIG. 4c is an isometric view of liquid meniscus support member 26. Aperture 27 is shown in the face of development surface 28. Aperture 27 is shown above entrance edge 29 whereby development liquid entering development surface 28 through aperture 27 flows over and down development surface 28 towards entrance edge 29. This process is more completely described in conjunction with the illustration of FIG. 2e.  
  FIG. 4e shows a cross-sectional and isometric view of liquid meniscus support member 26 showing the development liquid entrance channel 31 through meniscus support member 26 which is connected to aperture 27 located in the surface of the development surface 28. Also shown is supply line I6 which may be connected to any suitable means for supplying development liquid to the development area, e.g., a supply pump or a development liquid reservoir.  
  It will be understood that various other changes of the details, materials, steps, arrangement of parts and uses which have been herein described and illustrated in order to explain the nature of the invention will occur to and may be made by those skilled in the art upon reading of this disclosure and such changes are intended to be included within the principle of this invention.  
 EXAMPLE I An imaging member is provided comprising a supporting substrate of aluminized Mylar, a polyester resin film available from DuPont, with a vacuum evaporated. substantially transparent, electrically conductive layer of aluminum thereon, and a softenable layer about 2 microns thick of Piccopale H-Z, a thermoplastic hydrocarbon resin produced by the polymerization of unsaturates derived from the cracking of petroleum, available from Pennsylvania Industrial Chemical Corp.; and a fracturable layer of migration material of selenium, about 0.2 microns in thickness, vacuum evaporated onto the softenable layer by the process disclosed in application Ser. No. 423,]67, filed Jan. 4, 1965, now abandoned, and application Ser. No. W52 1 filed Mar. 17, 1970, now US. Pat. No. 3,598,644. This member is then electrostatically charged positive, typically under darkroom conditions and exposed to a negative lined copy of an original with white line for about t seconds. The above imaging member is now latently imaged.  
 EXAMPLE II An imaging member similar to the description in Example except having a softenable layer comprising a customed synthesized, /20 mole percent copolymer of styrene and hexylmethacrylate having an intrinsic viscosity of about 0.179 dl/gm (when measured in toluene), is initially imaged as described in Example I.  
 EXAMPLE III An imaging member as described in Example I and an apparatus taught in copending application Ser. No. 300,940, filed Oct. 26, 1972, and illustrated in FIG. 5 of Ser. No. 300,940 comprising a meniscus support member similar to the meniscus support member 13 of FIG. 3a in the instant application is utilized. However. the meniscus support member does not have an electrode present in the development surface of the meniscus support member. The development liquid. 1,1,1 trichlorethane is supplied to the liquid meniscus support member development surface at a rate of 2 cc per minute. Film speeds were from about /2 inch per second to about 2 inches per second. An undesirable amount of background material. i.e.. unmigrated migration material, remains on the developed imaging member when the member is processed at speeds of 2 inches per second with a 4 inch meniscus support member.  
 EXAMPLE IV The same meniscus processor (no electrode present in the development surface of the meniscus support member) as described in Example 111 is used to develop a migration imaging member as described in Example 11. The same process steps and parameters are used. An undesirable amount of background material. i.e.. unmigrated migration material, remains on the developed imaging member when the member is processed at speeds of 2 inches per second with a 4 inch meniscus support member.  
 EXAMPLE V The same meniscus processor (no electrode present in the development surface of the meniscus support member) as described in Example 111 is used to develop migration imaging film as described in Example 1. The imaging member is processed through the apparatus at a speed of 1.36 inches per second with the distance between the meniscus support member and the migration imaging member support member. i.e.. a roller similar to the roller shown in FIG. 3a. roller in the instant application, of 0.015 inches. The spacing between the migration imaging film and the liquid meniscus support member is 0.012 inches. Different rates of flow of the liquid solvent into the development area on the development surface of the liquid meniscus support member is used, i.e.. 6 ml per minute, 8 ml per minute, 10 ml per minute, ml per minute, and ml per minute. As the flow rate increases. the development liquid removes a greater portion of the softenable material until at about 20 ml per minute all of the softenable material is removed from the migration imaged member thereby leaving no protective coating upon the member. Therefore. since there is no softenable material remaining on the imaged member. all the background material, i.e., unmigrated migration material has been removed. These liquid meniscus developed imaging members contain either inacceptable amounts of background material or all of the softenable material is undesirably removed resulting in no protective coatings remaining on the members.  
 EXAMPLE V1 The same meniscus processor as described in Example V is used to develop a migration member as described in Example 11. The same process steps and parameters are used. The same results obtained in Example V are obtained.  
 EXAMPLE Vll An imaging member as described in Example 1 and an apparatus as described and illustrated by FIG. 4a is used. The liquid meniscus support member is produced from Delrin. an acetal resin which may be obtained from DuPont. The liquid meniscus support member is adjusted in all directions for initial alignment. The meniscus support member 26 as shown in FIG. 4a is advanced about an imaginary circle to a position of about to an imaginary radius of the imaginary circle which is perpendicular to the horizontal plane. Therefore. the meniscus support member is now advanced in a position which is approximately 90 to a horizontal plane. as shown in H0. 4a. Development solvent is introduced from a reservoir through a supply line into a passageway through the meniscus support member through an aperture located about 1 /8 inches from the exit edge of the development surface. Fresh development liquid is introduced near the exit meniscus which reduces carry out of unmigrated particles on developed imaging member as background. Furthermore. the solvent is introduced through an aperture which is perpendicular to the path of the member so that it will provide more solvent in a direction opposite the direction of the movement of the imaging member. The total shoe length is about 4.25 inches. Another meniscus support member is used where the aperture enters the development surface at an angle of 45 towards the entrance edge of the liquid meniscus support member. The entrance of the aperture at this angle further facilitates development in that it forces development liquid to immediately travel in the opposite direction of the movement of the migration imaging member and allows for more turbulence, i.e.. removal of residual material. When the aperture enters the development surface at a 45 angle, then the aperture is located approximately 1% inch from the exit edge of the development surface. A migration imaging member is developed at a rate ;of 1.4 inches per second and flow rates of solvent are from about 10 to about 20 ml per minute. Excellent imaged migration imaging members are obtained which contain no background thereon using either type of meniscus support members.  
 EXAMPLE VIII The same meniscus processor as described in Example Vll is used to develop a migration imaging member as described in Example 11. The same process steps and parameters as in Example Vll are used. Excellent image migration imaging members are obtained which contain no background thereon.  
 EXAMPLE lX The apparatus and imaging member used in Example Vll are used utilizing development liquids comprising 60 percent 1,1,1 trichlorethane and 40 percent methylene chloride by volume. Process speeds of 5 inches per second are used. Excellent background removal of unmigrated migration particles from imaged migration imaging members is obtained resulting in excellent imaged members containing a protective coating.  
 EXAMPLE X The apparatus and imaging member of Example Vll are used. The development liquid used is 55 percent methylene chloride and 45 percent 1,1,1 trichlorethane by volume. The member is process at 7.3 inches per second. The imaged member exhibits excellent qualities such as a protective coating over the image with no background material being present. i.e.. migration material.  
 EXAMPLE XI An apparatus is utilized as illustrated in FIG. 3a of the instant application. The meniscus support member contains an aperture entering the development surface at a 45 angle toward the entrance edge of the development surface. The aperture being about l.3 inches from the entrance edge of the development surface. In addition. an electrode is used which is located in the development surface approximately 1.5 inches from the exit edge of the development surface. The electrode is about 1.25 inches long and about 2 inches wide. The imaging member is processed at inches per second with the electrode containing a positive voltage of 40 volts. The electrode removes the unmigrated migration material which results in excellent image members being produced which contain a protective coating of softenable material.  
 EXAMPLE Xll An apparatus is utilized as illustrated in FIG. 3a of the instant application except the meniscus support member does not contain an electrode. In the previous Example Xl. the imaging member is processed at a speed of 5 inches per second and a solvent flow rate of ml per minute. However. utilizing the instant apparatus without an electrode in order to obtain similar results as obtainable in Example Xl. the solvent flow rate must be increased to 60 ml per minute. A high solvent rate will completely remove all of the softenable material from the image member thereby leaving no fixative material, i.e.. protective material, for the image. It may be demonstrated that by the utilization of and electrode. it is possible to gain at least a percent increase in processing rate. Furthermore. the electrode may be used to reduce the rate of solvent consumption by as much as 50 percent. In both cases. the basic imaging properties of the migration imaging member is not affected since the migration image is already formed by the time the electrodes enters the process.  
 What is claimed is:  
  1. An apparatus for developing migration imaging members comprising:  
 a meniscus support member with a surface adapted to receive a migration imaging member comprising a base having a development surface spaced adjacent and parallel to the longitudinal path of a migration imaging member, said development surface having a concave cross-section, said development surface having both an entrance edge and an exit edge, said development surface having at least one aperture connected to at least one passageway through said meniscus support member whereby development liquid may be supplied to said development surface, said aperture located sufficiently close to the entrance edge of said development surface to prevent solvent-vapor development ofa migration imaging member. said development surface containing an electrode which biases the path of said imaging member which removes residual material from a developed imaging member. said electrode being positioned along said path of said imaging member after said aperture and before said exit edge of said development surface; and  
 unmigrated means for providing a migration imaging member in the path spaced adjacent said development surface of said meniscus support member.  
  2. The apparatus according to claim 1 additionally comprising a meniscus across said path bounding at least in part a volume of liquid capable of developing a migration imaging member, said meniscus bounded at least in part by said development surface of said support member and said means for providing a migration imaging member in said path adjacent said development surface of said meniscus support member.  
  3. The apparatus according to claim 1 wherein the width of the meniscus support member is substantially the same width as the development surface of a migration imaging member being processed.  
  4. The apparatus according to claim 1 wherein the aperture is located a distance from the entrance edge of the development surface of from about 1.0 percent to about 30.0 percent of the total length of the development surface.  
  5. The apparatus according to claim 1 wherein the aperture is located a distance from the entrance edge of the development surface of from about 15 percent to about 25 percent of the total length of the development surface.  
  6. The apparatus according to claim 1 wherein the electrode is located a distance from the exit edge of the development surface of from about 1.0 percent to about 50 percent of the total length of the development surface.  
  7. The apparatus according to claim 1 wherein the electrode is located a distance from the exit edge of the development surface of from about l5 percent to about 45 percent of the total length of the development surface.  
  8. The apparatus according to claim 1 wherein the development surface has a concave cross-section extended through an are from about 30 to about l25 on an inside radius of from about 1.5 inches to about 8.0  
 inches of said arc.  
  9. The apparatus according to claim 1 wherein said means for providing a migration imaging member in the path spaced adjacent said development surface is from about 2 mils to about 25 mils in distance from said development surface.  
  10. The apparatus according to claim 1 wherein said means for providing a migration imaging member in the path spaced adjacent said development surface is from about 6 mils to about 15 mils in distance from said de velopment surface.  
  11. The apparatus according to claim 1 wherein the length of said development surface between the entrance edge and exit edge and along the surface of said development surface is from about 1 to about 30 inches.  
  12. The apparatus according to claim 1 wherein the length of said development surface between the entrance edge and exit edge and along the surface of said development surface is from about 3 to about 5 inches.  
  13. The apparatus according to claim 1 additionally comprising means for advancing a migration imaging member in said path.  
  14. The apparatus according to claim 13 wherein the means for advancing a member in said path is electrically conductive.  
  115. The apparatus according to claim 13 wherein the means for advancing a migration imaging member in said path is a flexible member which additionallypasses between the meniscus support memberand the means for providing the imaging member in the path.  
  16. The apparatus according to claim wherein the flexible member comprises an endless belt.  
  17. The apparatus according to claim 1 additionally comprising means for biasing an imaging member in the path between the electrode and the means for providing a migration imaging member in the path.  
  18. The apparatus according to claim 1 wherein said means for providing a migration imaging member in said path comprises a surface having a convex crosssection, said surface being contiguous the path of a migration imaging member.  
  19. The apparatus according to claim 18 wherein the means for providing a migration member in said path comprises a roller.  
  20. The apparatus according to claim 1 additionally comprising a means for providing development liquid to the development surface through the aperture and passageway in the meniscus support member.  
  21. The apparatus according to claim 20 wherein said means for providing development liquid to the develop ment surface so provides said liquid through a plurality of apertures and passageways in the meniscus support member.  
  22. The apparatus according to claim 1 wherein the aperture enters the development surface at an angle toward said entrance edge of from about 20 to about 90 in relationship to the development surface.  
  23. An apparatus for developing migration imaging members comprising:  
 a meniscus support member with a surface adapted to receive a migration member comprising a base having a development surface spaced adjacent and parallel to the longitudinal path of a migration imaging member. said development surface having a concave cross-section. said development surface having both an entrance edge and an exit edge, said development surface having at least one aperture connected to at least one passageway through said meniscus support member whereby development liquid may be supplied to said development surface. said aperture located sufficiently close to the exit edge of said development surface to prevent residual migration material from the development of a migration imaging member from exiting on an image member, said meniscus support member capable of being advanced about an imaginary circle up to about 90 on either side of an imaginary radius of said circle which is perpendicular to the horizontal plane. the circumference of said circle being coincidental with an arc of the concave cross-section of said development surface of said meniscus support member, said meniscus support member being in an advanced position sufficiently to allow said entrance edge to be located below said aperture allowing development liquid entering said development surface through said aperture to flow over said development surface toward said entrance edge; and  
 means for providing a migration imaging member in the path spaced adjacent said development surface of said meniscus support member.  
 24. The apparatus according to claim 23 additionally comprising a meniscus across said path bounding at least in part a volume of liquid capable of developing migration imaging member, said meniscus bounded at least in part by said development surface of said meniscus support member and said means for providing a migration imaging member in said path adjacent said development surface of said meniscus support member.  
  25. The apparatus according to claim 23 wherein the width of the meniscus support member is substantially the same width as the development surface of a migration imaging member to be processed.  
  26. The apparatus according to claim 23 wherein the aperture is located a distance of from about 1.0 percent to about 30.0 percent of the total length of the development surface from said exit edge of said development surface.  
  27. The apparatus according to claim 23 wherein the aperture is located a distance of from about 5 percent to about 25 percent of the total length of the development surface from the exit edge of the development surface.  
  28. The apparatus according to claim 23 wherein the development surface has a concave cross-section extended through an arc from about 30 to about l25 on an inside radius from about 1.5 inches to about 8.0 inches of said arc.  
  29. The apparatus according to claim 23 wherein said means for providing a migration imaging member in the path spaced adjacent said development surface is from about 2 mils to about 25 mils in distance from said development surface.  
  30. The apparatus according to claim 23 wherein said means for providing a migration member in the path spaced adjacent said development surface is from about 6 mils to about 15 mils in distance from said development surface.  
  31. The apparatus according to claim 23 wherein the length of said development surface between the entrance edge and exit edge along the surface of said development surface is from about 1 inch to about 30 inches.  
  32. The apparatus according to claim 23 wherein the length of said development surface between the entrance edge and exit edge along the surface of said development surface is from about 3 inches to about 5 inches.  
  33. The apparatus according to claim 23 additionally comprising means for advancing a migration imaging member in said path.  
  34. The apparatus according to claim 23 wherein the means for advancing a migration imaging member in said path is a flexible member which additionally passes between the meniscus support member and the means for providing the imaging member in the path.  
  35. The apparatus according to claim 34 wherein the flexible member comprises an endless belt.  
 36. The apparatus according to claim 23 wherein said means for providing a migration imaging member in said path comprises a surface having a convex crosssection. said surface being contiguous the path of a migration imaging member.  
  37. The apparatus according to claim 36 wherein the means for providing a migration member in said path comprises a roller.  
  38. The apparatus according to claim 23 additionally comprising a means for providing development liquid to the development surface through the aperture and passageway in the meniscus support member.  
 path of said imaging member a distance from the exit edge of the development surface of from about 1.0 percent to about 70 percent of the total length of the development surface.  
  41. The apparatus according to claim 40 wherein the distance of the electrode from the exit edge is from about It) percent to about 50 percent of the total length of the development surface.