MXPA96003409A - Method / apparatus to apply organic pigment with ac effect - Google Patents

Abstract

The present invention relates to a method and apparatus for "image formation by field effect" of moving substrates, such as paper webs. Non-magnetic, non-conductive organic pigment having an average particle size of about 5 to 20 microns, is electrically charged to a level of at least about 8 micro Coulombs / gram and then a first roller with a conductive surface is brought into association such that the organic pigment particles adhere to the surface. The organic pigment particles are preferably kept in an electrostatic fluidized bed and charged by a corona element into the bed. A set of primary pin or stylet electrodes are selectively energized or de-energized to provide write or write condition, respectively using a computer to switch the electrodes in or out of operational connection to a source of electric potential. The organic pigment particles are transferred from the first roll to a substrate either directly (after passing beyond the primary electrodes), or first transferred to a second roll which then carries the organic pigment particles in contact with the substrate. If a second roller is used, the primary electrodes may be in association with the first roller, or between the first roller and second rollers to transfer only "write" organic pigment to the second roller.

Description

METHOD / APPARATUS FOR APPLYING ORGANIC PIGMENT WITH FIELD EFFECT BACKGROUND AND COMPENDIUM OF THE INVENTION Commercially impactless printing systems typically use a method to reveal organic pigment (liquid or dry powder) in a latent electric or magnetic image created by some means of writing. With the creation of the latent image in an image forming cylinder, some means are associated to create the image and associated conditioning means for cleaning and separation of residual image. All these components wear out during system operation and must be added to the cost of each printed page. The organic pigment itself costs (in 1994) approximately $ 0.0006 to $ 0.001 per page. Adding the rest of the consumable components, the cost is increased to a range of $ 0.0625 to $ 0.0065 per page.

Printing without impact of latent image contributes with a P cost of considerable additional image formation. Direct-to-paper imaging systems, such as inkjet technologies, only contribute to the cost of the ink; however, many of these technologies do not obtain imaging as convenient, fast or versatile as the latent image forming systems. Another technology that is not commercial but attempts to obtain direct-to-paper imaging (this is without a latent image) is the magneto-style technology exemplified by US Patents. Nos. 3,816,840, 4,402.00 and 4,464,672. This technology uses a dry, magnetically attractable, electronically conductive organic pigment that forms a connection path from the primary to the secondary electrode. The "writing" condition of the organic pigment is the active electrode condition and extra organic pigment is removed by a magnetic field. Typically, it is employed to inductively charge the organic pigment for the "write" condition and the secondary electrode employs a dielectric receptor material thereon. This technology has not been commercial however, primarily due to problems of image formation and background separation, as well as problems with transfer of the organic pigment to a substrate. Another proposed technology for direct-to-paper image formation is called direct electrostatic printing fl (DEP = Direct Electrostatic Printing) and is exemplified by US Patents Nos. 4,860,036 and 4,810,604. This technology typically employs some kind of organic pigment transporter that moves the organic pigment past the primary electrodes that are formed by multiple openings, with an electrically insulated base member, coated on one side with a continuous conductive layer of metal and on the other side. opposite side with a segmented conductive layer. Organic pigment through the openings in a weft that moves beyond a stationary backup shoe or electrode that can be connected to potential sources, either for printing or cleaning operations. The pigment supply system in the DEP technology leaves much to be desired, and the dual conductive openings spaced apart by an insulating member are more complex than what is desired. In accordance with the present invention, there is provided a method and apparatus that are capable of achieving? direct-to-paper image (this is without a latent image) in a simple but effective way. The technology of the present invention can be referred to as "image formation with field effect". The invention uses non-magnetic, non-conductive organic pigment, which does not form a connection path from the primary or secondary electrodes, has the "write" condition when the primary electrode is de-energized, removes extra organic pigment with an electric ßr field, does not employs inductive charge of the organic pigment for a condition of "writing" beginning and uses simple primary electrodes, typically simple stylet or pin electrodes arranged in a set. In a field effect method, only the electrostatic adhesion force dominates in control of the organic pigment in a "secondary electrode" (typically on a conductive surface that can be positively or negatively charged or grounded, such as a roller ijF with a conductive surface) and the image formation is subtractive in nature (that is, the organic pigment in the non-image areas is removed by the primary electrodes). In accordance with one aspect of the present invention, a method for applying an organic pigment image to a mobile substrate (typically paper web), using non-magnetic, non-magnetic organic pigment having an average particle size of 5 to 20 microns, at least one first moving conductor member and a set of first electrodes is provided. The method comprises the steps of substantially consecutively and continuously: (a) Charge electrically the non-conductive, non-magnetic organic pigment having an average particle size of 5 to 20 microns at a level of at least about 8 micro.

Coulombs / gram. (b) Bring the first conductor member in motion, in operative association with the organic pigment JpP electrically charged from step (a) in such a way that the pigment particles adhere forming a layer. (c) 0 selectively energize individual primary electrodes of the set of primary electrodes, to cause them to apply electric fields to the organic pigment particle layer in a non-writing condition, to effect separation of pigment particles when the applied electric field 5 exists At a level greater than a static electrophysical adhesion force in the organic pigment particles in the layer, the electric field applied by the charge in the organic pigment is greater than Q2 / (16 * 7T * e0 * r2), in where Q is the charge of organic pigment, e0 is the dielectric constant, and r is the particle radius i of organic pigment; or selectively de-energizing individual primary electrodes from the set of primary electrodes, to cause them not to apply electric fields to the organic pigment particle layer in a writing condition, wherein the organic pigment particle layer simply passes beyond the set of electrodes primary, without the particles of organic pigment being removed from the layer. (d) Transferring the remaining organic pigment particles to the first conductive member after it passes beyond the set of primary electrodes to the moving substrate. And (c) fusing the organic pigment particles to the substrate. Step (c) is typically practiced to apply a ß ^ electric field of more than about 1.6 volts / μM, when in the non-writing condition. Step (c) is typically practiced further, such that the magnitude of the electric field applied in the non-write condition is equal to CV ^ -V ^ / D, where V1 = the electric potential of the primary electrode, V2 = the electric potential in the first conductive surface and D = the separation distance between the primary electrode f and the first conducting surface, D = approximately 75-250 microns. Typically, the organic pigment is in an electrostatic fluidized bed during the practice of step (a), as illustrated in European published patent application 494454, and the first surface moves beyond the fluidized bed in the practice of step (b), and the organic pigment is removed in the non-writing condition during the , and practice of step (c) returns to the fluidized bed. From ? Preferably, the primary electrodes are pins or stilettos, and the first conductive surface is the outer surface of the first roller. In that case, step (d) is practiced by bringing the outer surface of the first roller into contact with the moving substrate and by applying an electric transfer force (for example using a transfer ring on the opposite side of the screen). moving paper from the roller) to the organic pigment in 9 the outer surface of the first roller, to cause the organic pigment to be transferred from a first roller to the substrate. Alternatively, a second roller having a second conductive outer surface can also be provided, in which case step (d) can be practiced by electrically transferring the organic pigment from the first roller to the second roller, and then carrying the outer surface of the second roller. roller in contact with the moving substrate, and by applying an electrical transfer force to the organic pigment on the outer surface of the second roller, to cause the organic pigment to transfer from the second roller to the substrate. Step (c) can be practiced by using the primary electrode disposed between the first and second rollers or associated with the first remote roller from the second roller. When the two rollers are used, you can The premature transfer of the organic pigment from the first roller to the second roller is provided by shielding the rollers from each other remote from the closest proximity area between them. Step (c) is typically practiced by electronically switching the connection of each pin or primary electrode stylet of the assembly to a source of electrical potential when controlling electronic switches used by a computer. A flow shield can also 9? provided just mounted "downstream" of the set of primary electrodes in the direction of movement of the first roll to cause the organic pigment particles removed from the first roll to fall by gravity in the fluidized bed below. According to another aspect of the present invention, an image-forming apparatus with field effect is provided, comprising the following elements: an electrostatic fluidized bed of non-magnetic, non-conductive organic pigment particles. Means for mounting a substrate in motion in which organic pigment is to be applied.

Means for electrically charging organic pigment particles in the fluidized bed. A first roller having a conductive outer surface mounted for rotation adjacent the fluidized bed to receive the charged organic pigment particles from the fluidized bed in a ^ layer on the surface. A set of primary electrodes. Means for selectively applying electric potential or not applying electric potential to the individual primary electrodes depending on whether the writing or non-writing condition exists. And means for transferring organic pigment from the first roller to a moving substrate mounted by the means for mounting a substrate in motion. The preferred assembly comprises a set of pin or stylet electrodes, and the assembly may already be 9 mounted adjacent although spaced apart from the first roller and between the fluidized bed and the substrate (in which case the means for transferring organic pigment transfers organic pigment from the first roller directly to the moving substrate), or a second roller may be provided between the first roller. roll and substrate. In this case, the primary electrodes can already be associated with the first electrode or can be arranged between the rollers, such that only the Wk organic "writing" pigment is transferred from the first roller to the second roller. The pins or stilettos of the assembly can be mounted so that they are spaced approximately 75-250 microns from the first roll, or between the rolls.

A flow shield can be provided to cause the organic pigment removed by the non-writing conditions of the primary electrodes to fall back to the bed Fluidized, as well as a shield between the first and second rollers. The means for electrically charging organic pigment particles in the fluidized bed can comprise a rotating cylinder with a plurality of corona points or a corona wire submerged in the fluidized bed. According to another aspect of the present invention, there is provided an apparatus for image formation with field effect, comprising the following elements: Means for mounting a substrate in motion. A source of particles of Wr pigment loaded. A first roller having a conductive outer surface mounted for rotation adjacent to the source to receive charged organic pigment particles from the source in a layer on the surface. A set of primary pin or stiletto electrodes. Means for selectively applying electric potential or not applying electric potential, to the individual primary pin or stylet electrodes, depending on whether there is a no condition? writing or writing. And means for transferring organic pigment from the first roller to a moving substrate mounted by the means for mounting a substrate in motion. The conductive outer surface of the first roller can be coated with or comprise a conductive hard metal coating; for example, it can be coated with hard chromium, tungsten carbide, silicon carbide or a Diamond Type Nanocomposite. It is the primary objective of the present invention to provide a system and method for direct-to-paper image formation, simple yet effective. The method and apparatus for application of organic pigment with field effect of "direct writing" of the invention, do not have to deal with latent image, the rollers used are conductors with hardened surfaces that do not require particular conditioning, the set of imaging electrodes (primary) do not contain parts that wear out and are not in ^ r contact with any moving surface and in general the only consumable product is the organic pigment itself. These and other objects of the invention will be clear from an inspection of the detailed description of the invention and from the appended claims.

W BRIEF DESCRIPTION OF THE DRAWINGS FIGURE IA is a schematic side view showing the operation of the apparatus and method for applying pigment with field effect according to the invention; 5 FIGURE IB is a schematic top view of the apparatus of FIGURE IA; FIGURE 2 is a graphical representation illustrating the percentage of organic pigment released under the influence of a primary electrode according to the invention, with increased applied electric field IV; FIGURE 3 is a schematic side view of a preferred embodiment of the exemplary apparatus in accordance with the present invention; FIGURE 4 is a side detail view of the primary electrode portion of the apparatus of FIGURE 3; FIGURE 5 is a view like FIGURE 3 for another embodiment of the apparatus according to the invention; FIGURE 6 is a view like FIGURE 3 for yet another embodiment of the apparatus according to the present invention; FIGURE 7 is a detailed side view of the primary electrode and related components of the apparatus of FIGURE 6; and FIGURE 8 is a view like that of FIGURE 3 5 for yet another embodiment.

W DETAILED DESCRIPTION OF THE DRAWINGS FIGURES IA and IB are designed to illustrate the basic principles of field effect pigment application technology, in accordance with the present invention. The basic elements of the apparatus comprise a supply of organic pigment (a non-magnetic, non-conductive organic pigment) schematically illustrated by reference numeral 10, a moving conductive substrate 11, which may have a particularly hard conductive coating 12 (for example formed of hard chrome, tungsten carbide, silicon carbide or Diamond Type Nanocomposites) moving in the direction 13, and a set of primary electrodes 14 of conductive material that can be electrically derived in the "write / write" condition when using the voltage source 15 and the high-speed switching circuitry 16 which is controlled by a computer 17. Only one electrode 14 is illustrated in FIGURE IA, but the nature of the type? r? The set of electrodes is illustrated in FIGURE IB. The electrodes 14 may be in a single line in the assembly as illustrated in solid line in FIGURE IB, or they may be arranged in a two-dimensional array, as indicated when the electrodes are considered with dotted lines 14 'of FIGURE IB. FIGURE IB only shows two of the electrodes 14 connected to the electronic switches 16, but there will be v. It is understood that everything will be connected to the source of electric potential 15 through an electronic switch 16. The conductive surface 11 that can be considered a secondary electrode, can be directed either to electrical polarity by a voltage source 18 or maintained at a electric ground depending on the particular application. The outer surface of the liner 12 is ground and polished to a surface roughness of .0102 mm (four micro inches - more) or better. * The layer of organic pigment 19 which is deposited on the surface 11, 12, typically has a thickness T; normally layer 19 is a bi-layer of organic pigment with a thickness of approximately 20 microns. The preferred average particle size diameter of the organic pigment is approximately 10.5 microns, however, the process works with organic pigments with approximately 5-20 microns of average particle size. The organic pigment in layer 19, | P is typically loaded at a level of at least 8 μC / g (either positive or negative) and more typically at 10 μC / g charged in a mass ratio by field loads (load Panthenier) using a high-voltage corona source. That is, the supplied voltage is in the order of approximately 7 kV. The primary electrodes 14 may be of any number of cross-sectional shapes, such as the round shapes illustrated in solid lines in FIGURE IB, - • wr or the flat polygonal shapes (eg, squares) illustrated at 14 'in dotted lines in FIGURE IB. The charge 20 of each electrode 14 - which is preferably in the form of a pin or stylet, as schematically illustrated in FIGURES IA and IB - is mounted spaced at a distance D from the surfaces 11, 12. The preferred distance D is about 75-250 microns, and during operation, no electric path is created by the organic pigment between the electrode 14 and the surface / electrode 11, 12. The electrode 14 is energized in the non-write condition, and when energizes, the organic pigment particles within the field influence generated by the electrode 14, jump "out" of the surfaces 11, 12 (the electric field strength in the pigment particles that have exceeded the electrostatic bond strength) as is indicated in B in FIGURE IA. The organic pigment image 22, which passes under the electrode assembly 14, when it is in the - ^ T condition of "writing" passes as indicated by the directional arrow C to the transfer position where the image is transferred to the substrate and fused by conventional means (for example heating). In the "non-writing" condition, a primary electrode 14 is switched to the level of derivation that is provided by the voltage source 15.

This forms an electric field between the primary and secondary electrodes. The field is of magnitude, where V. is the potential at the primary electrode 14, V2 is the potential at the secondary electrode (11, 12) and D is the distance at separation between the electrodes. The organic pigment layer 19 is separated from the secondary electrode 11/12 under this condition, when the electric field strength in the organic pigment particles exceeds the electrostatic adhesion force, ie M > FE > Fad or Q * E > Q2 / (4 * p * e0 * R2) to a first order approximation. Q is the charge in the pigment, e0 is the dielectric constant, and r is the radius of organic pigment particles. Separated particles B are removed from the surface by electric fields only and recycled to the surface of organic pigment 10 (for example the electrostatic fluidized bed). In the "write" condition, the lead 15 of the electrode 14 is interrupted by the computer control 17 of the switch 16, allowing the organic pigment image 22 to continue and be directed to the transfer position where the image is displayed. transfers to the substrate (not shown in FIGURES IA and IB) and merged by conventional means. Since at present the supply of organic pigment 10 will comprise a large population of particles that vary in size and therefore total amount of charge, not all particles will be released from surfaces 11, 12 with the same applied electric field. With variable loads and equal diameters, there is a range in magnitude of electric field on which the particles of the surfaces are detached 11, 12 and FIGURE 2 schematically illustrates a typical graph of the percentage of organic pigment released with the electric field applied in an increased form. The - ^ organic pigment transfer begins at a threshold level ^ under 23 and continues until the entire population is transferred after passing a total transfer field magnitude 24. In practice, this is not a total transfer, but represents approximately 95%, probably due to some organic pigment particles of erroneous charge or very low charge. To ensure a total transfer of the organic pigment between the surfaces 14, 11/12 of FIGURES IA and IB, the electric field should exceed the magnitude of? total transfer 24 in some nominal amount. In practice, the total transfer amount is approximately 0 1.6 volts / μM. Therefore, electric fields greater than these should be used, and in current practice, fields are used within the range of approximately 2.2-2.4 volts / μM. FIGURES 3 and 4 schematically illustrate a preferred apparatus using the principle of organic pigment supply with basic field effect illustrated in FIGS. 1 and 2. In this embodiment, the source of organic pigment comprises a fluidized bed of particles. of organic pigment (for example having an average particle size of about 5-20 microns) arranged inside the container 26 and having a porous plate 27 through which fluidizing air passes, supplied from the air plenum 28. Means are provided for electrically loading the organic pigment particles in the bed ^ 25. These means are illustrated schematically at 29 in FIG. 3 and comprise a cylinder 30 that rotates within the bed and has crown points (for example four sets of equally spaced points) around its surface. Alternatively, these mounts may comprise a corona wire or any other convenient mechanism for imparting a load to the non-magnetic, non-magnetic organic pigment particles within the bed 25. The electrical charge means 29 are connected to a source of illustrated electric potential "Schematically at 32 in FIGURE 3. Arranged on the bed 25 is a first roller 33 having a conductive surface 34. The roller 33 can be connected to a source of electric potential 35 (either a positive or negative source) or It can be electrically connected to ground. It is typically mounted for rotation about a horizontal axis and energized by a conventional motor 5. In operative association, there is a J set of primary electrodes schematically illustrated in 36 in FIGURE 3. The assembly 36 corresponds to the primary electrodes 14, 14 'of the assembly illustrated in FIGURES IA and IB, while the roll surface 34 corresponds to the surface 11/12 in FIGURE A. The primary electrodes 36 are illustrated in more detail in FIGURE 4. Each electrode 36 typically comprises a shielded shielded plate 37, an insulating layer 38, ^ - and a set of styli or driver pins 39. The ll pins 39 are connected to an electronic negative pulse switch 40 controlled by a computer 41. There is a space 42 with "d" dimension in FIGURE 4, typically about 75-250 microns, between the surfaces 34 and the closest surfaces of the pins 39. When the computer 41 energizes a pin 39 through the associated electronic switch 40, the organic pigment particles as indicated schematically at 43 in w? FIGURE 4, is made to "jump" from the surface 34. This condition of "non-writing" essentially removes the areas of "bottom" of the organic pigment on the surface 34 and returns the organic pigment particles forming them to the fluidized bed which is just below the electrodes 36. If a flow shield 44 or the like is desired, "downstream" of the primary electrodes 36 is provided in the direction 45 'of the rotation of the roller 33, to assist in returning the pigment organic material withdrawn 43 to the fluidized bed 25. After the organic pigment in the roller 33 passes beyond the primary electrodes 36, there will be only image areas (or what will become image) 45 on the surface 34. These areas of 45 image organic pigment should then be transferred to a moving substrate 46 (see FIGURE 3) such as a paper web. The substrate 46 is JL mounts by rollers, such as roller 47 or other conventional equipment to move a frame further and in contact with a rotating cylinder. In the embodiment illustrated in FIGURE 3, the transfer of the image areas 45 is accomplished using a second cylinder roller 48 having a conductive outer surface 49. The roller 48 is also typically connected to a source of electrical potential such as a source 50 illustrated schematically in FIGURE 3. The 9 ^ roller 48 is mounted for rotation with respect to an axis parallel to the axis of rotation of roller 33, and are mounted in such a way that the transfer point 51 between them is a small space in which the surfaces 49, 34 are in proximity immediate In order to avoid premature transfer of the organic pigment images 45 from the surface 34 to the surface 49 in the weak fields as the organic pigment images 45 approach the nearest proximity area 51, an electrical shield 52 is provided between the 45 images as they move in the 45 'direction into space 51.. The cylinder 48 is rotated in a direction 54 opposite the direction 45 '. In the transfer area 51, where the rollers 48, 33 are in the closest proximity, the same electric forces are applied as previously indicated, , causing the organic image-forming pigment 45 to transfer from the surface 34 to the surface 49. The roller 48 then rotates clockwise to a point of contact with the paper web 46 where a transfer medium - such as the conventional transfer crown 56 on the opposite side of the substrate 46 from the roll 48 - effects the transfer of the organic pigment images from the roll 48 to the web 46. The web 46 then continues to move in the direction 57 to a merger ~ Conventional 58 (for example, which applies heat to the organic pigment) which melts the organic pigment to the substrate 46. In order to remove excess organic pigment from the cylinders 33, 48, conventional scrapers 59, 60, the organic pigment are provided. withdrawn falls under the force of gravity to the fluidized bed 25. FIGURE 5 illustrates another exemplary embodiment according to this invention. In FIGURE 5, components "comparable with those of the embodiment of FIGURES 3 and 4 are illustrated with the same reference number." This embodiment differs from the embodiment of FIGURES 3 and 4 only in that the single roller 33 is provided. , and the organic pigment images 45 on the surface 34 are placed directly in contact with the moving substrate 46 (moving in the opposite direction to that illustrated in FIGURE 3.) Also in this particular situation, the roller 33 is connects to ground, as indicated schematically at 62, instead of a source of electric potential.In the embodiment of FIGURES 6 and 7, the components essentially identical to those in the embodiment in the FIGURES 2 and 4, are illustrated by the same reference number, while only comparable components are illustrated, the same number preceded only by "1". In the embodiment of FIGURES 6 and 7, the first roller 133 rotates in the direction 145 'opposite the direction? 45 ', and there is no primary electrode directly associated. In contrast, the primary electrodes illustrated schematically at 136 in FIGURE 6, and which are seen more clearly in the FIGURE 7, are mounted between rollers 133, 148. When the field is generated to create an image by the control of the computer 141 of the electronic switches 140 associated with each of the pins or stilettos 139, the image 145 is caused to rise from the surface 134 of the roller 133 on the surface 149 of the roller 148, while the organic pigment "bottom" remains on the surface 134 as illustrated at 64 in FIGURE 7. A current electrical field analysis of the configuration of the primary electrodes 136 and rollers 133, 148, illustrated in FIGS. 6 and 7, is performed with an analysis package of finite element called "ELECTRO". This demonstrates that the electrodes 136 can develop a field greater than 2.3 volts / μM at the surface 134, ^ sufficient to overcome the electrostatic adhesion force on the organic pigment particles at the surface 134. Once the organic pigment images 145 are transferred to the surfaces 149, are applied to the frame 46 in the same manner as described with respect to FIGURE 3, except that the address 154 is opposite to the address 54. FIGURE 8 illustrates another embodiment with components comparable to those of the modality of FIGURE 3, illustrated with the same reference number. In this embodiment, there is no set of stylus or pin electrodes, but rather transfer between the surfaces 34, 49 in the space 70 between them is provided basically in volume, the electronic switch 71 is controlled to selectively connect the voltage source 50 to roll 48 to cause transfer, or disconnect to avoid transfer. When transfer is desired, images (typically in the form of lines) are transferred to the surface 49 and then brought into contact with the substrate 46. If desired, the roller 48 can be constructed of a plurality of conductive rings ( less on its surface 49) separated by insulators, with a different switch 71 associated with each ring In this way it will be seen that according to the present invention, an advantageous method and apparatus for application of organic pigment with field effect are provided. The invention allows direct-to-paper image formation using very simple components, without parts that wear out and with the only consumable product that is the organic pigment itself. While the invention has been illustrated and described herein in what is currently conceived as the most practical and preferred embodiment thereof, it will be apparent to those with ordinary skill in the art that many modifications thereto can be practiced within the scope of the invention. invention, this scope will be granted the broadest ^ interpretation of the appended claims to encompass all equivalent methods and devices. 0 WHAT IS CLAIMED:

Claims (29)

1. Method for applying an organic pigment image to a moving substrate, using a non-magnetic, non-conductive organic pigment, having an average particle size of 5-20 microns, at least a first moving conductor member, and a set of primary electrodes, characterized in that it comprises the steps substantially consecutively and continuously of: (a) charging. electrically the non-magnetic, non-magnetic organic pigment having approximately an average particle size of 5-20 microns at a level of at least about 8 microns Coulo bs / gram; (b) bringing the first conductive member moving in operative association with the electrically charged organic pigment from step (a) so that the organic pigment particles adhere to it by forming a layer thereon; (c) selectively energize individual primary electrodes from a set of primary electrodes, to ~ cause them to apply electric fields to the organic pigment particle layer in a non-writing condition, to effect removal of the organic pigment particles when the applied electric field exists at a level greater than an electrostatic adhesion force on the particles of organic pigment in the layer, the electric field applied by the charge in the organic pigment is greater than Q2 / (16 * p * e0 * r2), where Q is the charge in the organic pigment, e0 is the rganic constant and r is the radius of organic pigment particles; or selectively de-energize individual primary electrodes from the set of primary electrodes so as not to apply electric fields to the layer of organic pigment particles in a write condition, wherein the layer of organic pigment particles simply passes beyond the set of electrodes primary without organic pigment particles being removed from the layer; f (d) transferring the remaining organic pigment particles in the first conductive member after it passes beyond the set of primary electrodes to the moving substrate; and (e) fusing the organic pigment particles in the substrate.

2. A method according to claim 1, characterized in that step (c) is practiced to apply an electric field greater than about 1.6 volts / μM when in the non-writing condition. ^

3. A method according to claim 2, characterized in that step (c) is further practiced in such a way that the magnitude of the electric field applied in the non-writing condition is equal to (V., -V2) / Or, where Vx = the electric potential of the primary electrode, V2 = is the electric potential in the first conducting surface and D = the separation distance between the primary electrode and the first conductive surface and where D = approximately 75-250 microns .

4. A method according to claim 1, characterized in that the organic pigment is in an electrostatic fluidized bed during the practice of step (a), and the first surface moves beyond the fluidized bed in the practice of the stage ( b), and wherein the organic pigment removed in the non-writing condition during the practice of i, step (c) returns to the fluidized bed.

A method according to claim 1, characterized in that the primary electrodes are pins or stilettos, and wherein the first conductive surface is the outer surface of a first roller; and wherein step (d) is practiced by bringing the outer surface of the first roller into contact with the moving substrate and by applying an electrical transfer force to the organic pigment to the outer surface of the first roller, to cause the organic pigment is transferred from the first roller to the substrate.

6. A method according to claim 1, characterized in that the primary electrodes are pins or stylets; and wherein the first conductive surface is the outer surface of a first roller; and further using a second roller comprising a second conductive outer surface; and wherein step (d) is practiced by electrically transferring the organic pigment from the first roller to the second roller, and then bringing the outer surface of the second roller into contact with the moving substrate, and by applying an electric force of Transfer to the organic pigment on the outer surface of the second roll to cause the organic pigment to transfer from the second roll to the substrate.

7. A method according to claim 6, characterized in that step (c) is performed by a first set of pins or stiletto electrodes arranged between first and second rollers.

8. A method according to claim 6, characterized in that step (c) is practiced by a first set of pins or stiletto electrodes associated with the first remote roller of the second roller.

A method according to claim 5, characterized in that the organic pigment is in an electrostatic fluidized bed during the practice of step (a) and the first outer surface of the roller is rotated beyond the fluidized bed in the practice of step (b) and wherein the organic pigment removed in the non-writing condition during the practice of step (c) falls back into the fluidized bed; and wherein step (c) is practiced by a set of primary pin or stiletto electrodes placed just above the fluidized bed. ^ 10.

A method in accordance with the claim 6, characterized in that it comprises the additional step of preventing premature transfer of organic pigment from the first roller to the second roller, by shielding the rollers from each other 5 remotes from the area of closest proximity between the rollers.

A method as described in claim 1, characterized in that the primary electrodes are pins or stilettos, and wherein step (c) is achieved by switching Jk electronic connection of each pin or stiletto l? Primary electrode from the assembly to a source of electrical potential when controlling electronic switches using a computer.

12. Apparatus for image formation with field effect, characterized in that it comprises: a fluidized bed 15 electrostatic of non-conductive, non-magnetic organic pigment particles; mounts for placing a substrate in motion, in which the organic pigment is to be applied, assemblies for electrically loading particles of organic pigment in the fluidized bed; a first roller that has 20 a conductive outer surface mounted for rotation adjacent to the fluidized bed, to receive charged organic pigment particles from the fluidized bed in a layer on its surface; a set of primary electrodes; means to selectively apply electrical potential, or not 25 apply electric potential to the individual primary electrodes ^, depending on whether the writing or non-writing condition exists; and means for transferring organic pigment from the first roll to a moving substrate placed by the means for mounting a moving substrate.

13. Apparatus according to claim 12, characterized in that the assembly comprises a set of pin or stylet electrodes, and wherein the assembly is mounted adjacent although spaced from the first roller and between the fluidized bed and the means for placing a substrate in motion; and wherein the means for transferring organic pigment comprises means for transferring organic pigment from the first roller, directly to a substrate in motion.

Apparatus according to claim 12, characterized in that the means for transferring organic pigment from the first roller to a moving substrate mounted by the means for placing a substrate in motion,? ^ Comprise a second roller having a conductive outer surface .

15. Apparatus according to claim 14, characterized in that the assembly comprises a set of pin or stylet electrodes mounted adjacent although spaced from the first roller and remote from the second roller, so that there are conditions of writing and not writing in association with the first roller.

16. Apparatus according to claim 14, characterized in that the assembly comprises a set of pin or stylet electrodes and wherein the assembly is mounted between the first and second rollers and placed in such a way that there are writing and recording conditions. no writing as the organic pigment is transferred between the first and second rolls. Apparatus according to claim 12, characterized in that the means for selective application comprise an electronic switch associated with each primary electrode and controlled by a computer. 18. Apparatus according to claim 12, characterized in that the means for transferring organic pigment from the first roller to a moving substrate 5 comprises means for transferring organic pigment directly from the first roller to a moving substrate. And 19. Apparatus according to claim 18, characterized in that the means for transferring organic pigment also comprises a transfer crown mounted on the opposite side of a substrate moving from the first roller. Apparatus according to claim 12, characterized in that the assembly comprises a set of 5 pins or stylets; and wherein the pins or stilettos of the assembly are mounted so that they are spaced approximately 75-250 microns from the first roller. Apparatus according to claim 12, characterized in that it also comprises a flow shield for 5 cause the organic pigment removed by the non-writing conditions of the primary electrodes to fall back into the fluidized bed. 22. Apparatus according to claim 12, characterized in that the means for electrically charging organic pigment particles in the fluidized bed comprise a rotating cylinder with a plurality of corona and submerged points in the fluidized bed. 23. An apparatus for image formation by field effect, characterized in that it comprises: means for mounting a substrate in motion; a source of charged organic pigment particles; a first roller that has a surface , conductive exterior mounted for rotation adjacent to the source V to receive particles of organic pigment charged from the source in a layer on its surface; a set of primary pin or stiletto electrodes; means for selectively applying electrical potential or not applying electric potential to the individual primary pin or stylet electrodes depending on whether a write or non-write condition exists; and means for transferring organic pigment from the first roller to a moving substrate mounted by the means for mounting a substrate in motion. 24. Apparatus according to claim 23, characterized in that the pins or stylets of the assembly are mounted in such a way that they are spaced approximately 75-250 microns from the first roller. Apparatus according to claim 23, characterized in that the means for transferring organic pigment from the first roller to a moving substrate mounted by the means for mounting a moving substrate comprise a second roller having a conductive outer surface. 26. Apparatus according to claim 25, characterized in that the set of pin or stylet electrodes is mounted adjacent although spaced from the first roller and between first and second rollers, such that there are writing and non-writing conditions in association with the first roller. 27. Apparatus according to claim 23, characterized in that the conductive outer surface of the first roller is coated with or comprises a conductive hard metal coating. Apparatus "according to claim 27, characterized in that the outer surface of the first roller is a coating of hard chrome, tungsten carbide, silicon carbide or diamond-type nanocomposite 29. Apparatus according to claim 25, characterized in that it also comprises an electrical shield placed between the first and second rollers, remote from the area of closest proximity between them, to avoid premature transfer of organic pigment from the first roller to the second roller. SUMMARY OF THE INVENTION A method and apparatus for "image formation by field effect" of moving substrates, such as paper webs, are provided. Non-conductive, non-conductive organic pigment having an average particle size of about 5 to 20 microns, is electrically charged to a level of at least about 8 micro Coulombs / gram and then a first roller with a conductive surface is carried in # Operational association with the electrically charged organic pigment so that the organic pigment particles adhere to the surface. The organic pigment particles are preferably kept in an electrostatic fluidized bed and charged by a corona element into the bed. A set of primary pin or stiletto electrodes are selectively energized or de-energized to provide write or non-write condition,,. respectively using a computer to switch the * ^ electrodes in or out of operational connection to a source of electrical potential. The organic pigment particles are transferred from the first roller to a substrate either directly (after passing beyond the primary electrodes), or first transferred to a second roller which then carries the organic pigment particles in contact with the latter. substrate If a second roller is employed, the primary 5 electrodes may be in association with the first roller, or between the first roller and second rollers to transfer only organic "writing" pigment to the second roller.