MXPA98002479A - Apparatus and process to reduce the accumulation of organic pigment of the surface of an element of electr - Google Patents

Abstract

The present invention relates to an apparatus and process for reducing the accumulation of organic pigment from the surface of an electrode member in a developing unit of an electro-statographic printing apparatus, providing an organic coating on at least a portion of the electro-member.

Description

APPARATUS AND PROCESS TO REDUCE THE ACCUMULATION OF ORGANIC PIGMENT OF THE SURFACE OF AN ELEMENT OF # ELECTRODE BACKGROUND OF THE INVENTION The present invention relates to methods, processes and apparatus for the development of images, and more specifically, to electrode members for use in a # unit of development in printing machines electrophotographic. Specifically, the present invention relates to methods and apparatuses in which at least a portion of an electrode member of the development unit is coated with a coating material, and in the embodiments, a low coating material. surface energy. In the embodiments, the history of the electrode member, the dampening and / or accumulation of organic pigment are controlled or reduced. Generally, the electrophotographic printing process includes charging a photoconductor member to a substantially uniform potential, for sensitizing the photoconductive member thereof. The loaded portion of the photoconductive member is exposed to a pale image of an original document being reproduced. This registers an electrostatic latent image on the member REF: 26851 photoconductor. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by placing a development material in contact therewith. Commonly, 5 two component and one component development materials are used. A typical two-component development material comprises magnetic carrier granules having organic pigment particles that adhere triboelectrically thereto. A development material of a component typically comprises organic pigment particles. The organic pigment particles are attracted to the latent image, forming an image of organic pigment powder on the photoconductive member. The image of organic pigment powder is subsequently transferred to a copy sheet. Finally, the organic pigment powder image is heated, to permanently melt it to the copy sheet in image configuration. One type of one-component development system is a development system without sweeping, which uses a dispensing roller to transport organic pigment charged to the development zone. At least one, and preferably a plurality of electrode members are very close to the dispensing roller in the development zone. An AC voltage is applied to the electrode members, forming a cloud * of organic pigment in the development zone. The electrostatic fields generated by the latent image attract organic pigment from the organic pigment cloud to develop the latent image. Another type of two-component development system is a hybrid-free development system that employs a magnetic brush development roller to transport carrier that has organic pigment that is adheres triboelectrically to it. A dispensing roller is used in this configuration also to transport charged organic pigment to the development zone. The dispensing roller and the magnetic roller are electrically polarized relative to one another. He The organic pigment is attracted to the dispensing roller from the magnetic roller. The electrically polarized electrode members separate the organic pigment from the dispensing roller, forming a cloud of organic pigment powder in the development zone, and the latent image attracts the organic pigment particles of the same. In this way, the latent image recorded on the photoconductive member develops with organic pigment particles.

Various types of development systems have been used before, as illustrated by the following descriptions. U.S. Patent No. 4,868,600 to Hays et al., The subject matter of which is incorporated herein by reference in its entirety, discloses an apparatus wherein a dispensing roller transports organic pigment to an opposite region of a surface on which a latent image is registered. A couple of members electrode is placed in the space between the surface of the latent image and the dispensing roller, and is electrically polarized, to separate organic pigment from the dispensing roller, to form a cloud of organic pigment. The organic pigment separated from the cloud develops the latent image. U.S. Patent No. 4,984,019, to Folkins, the subject matter of which is incorporated herein by reference in its entirety, discloses a development unit having a dispensing roller with electrode members disposed adjacent thereto in a development zone. A magnetic roller transports development material to the dispensing roller. The organic pigment particles are attracted from the magnetic roller to the dispensing roller. When the development unit is inactivated, the electrode members are * vibrate, to eliminate contaminants from them. U.S. Patent No. 5,124,749, given to Bars, 5 the subject matter of which is incorporated herein by reference in its entirety, discloses an apparatus in which a dispensing roller advances organic pigment to an electrostatic latent image recorded on a photoconductive member , where a plurality of Ten electrode wires are placed in the space between the dispensing roller and the photoconductive member. The wires are electrically polarized, to separate the organic pigment from the dispensing roller, to form a cloud of organic pigment in the space between the wires electrode and the photoconductor member. The organic pigment cloud develops the latent image. A cushioning material is deposited on a portion of the electrode wires, in the position of attachment to the electrode support members, for the purpose of dampen the vibration of the electrode wires. U.S. Patent Nos. 5,300,339 and 5,448,342, both to Hays et al., The subject matter of which is incorporated herein by reference in its entirety, describe a coated organic pigment transport roller containing a core with a * coating on it. U.S. Patent No. 5,172,170, given to Hays et al., The subject matter of which is incorporated herein by reference in its entirety, discloses an apparatus in which a dispensing roll advances organic pigment to an electrostatic latent image recorded on a photoconductor member. The dispenser roller includes a dielectric layer disposed around the circumferential surface of the roller between adjacent grooves. Primarily because the adhesion force of the organic pigment particles is greater than the detachment force generated by the electric field of the particles. electrode members in the development zone, is a problem in which the organic pigment tends to accumulate on the electrode members. The accumulation of organic pigment particles on the wire member causes the non-uniform development of the latent image, resulting in printing defects. The problem is aggravated by the fine powders and any components of the organic pigment, such as the high molecular weight, crosslinked and / or branched components, and the voltage interruption between the wire member and the * roller dispenser. A specific example of contamination by organic pigment results from the development of a document having solid areas that require a large concentration of organic pigment to be deposited at a particular position on the latent image. The areas of the electrode member that correspond to areas of high performance or high concentration of organic pigment tend to include a higher or lower accumulation of organic pigment, because of this different exposure to organic pigment yield. When the printer subsequently tries to develop another different image, the accumulation of organic pigment on the member of The electrode will give rise to a differential development of the newly developed image corresponding to the areas of greater or lesser accumulation of organic pigment on the electrode members. The result is a darkened or lightened band in the position corresponding to the solid area of the previous image. This is particularly evident in areas of immediate density, since these are the areas most sensitive to differences in development. These particular image defects caused by accumulation of organic pigment on the wires of * t electrode in the development zone are referred to as the history of the wire. Figure 5 contains an illustration of wire contamination and wire history. The contamination of the wire results when molten organic pigment 5 is formed between the electrode member and the dispensing member due to fine dusts of the organic pigment and any components of the organic pigment, such as high molecular weight, crosslinked and / or branched components, and the interruption of voltage between the member wire and roller dispenser. The history of the wire is a change in the development capacity because the organic pigment or the components of the organic pigment adhere to the upper part of the electrode member. Accordingly, there is a specific need for electrode members in the development zone of a development unit of an electrophotographic printing machine that provides a decreased tendency to build up organic pigment, to decrease the history of wire and wire contamination, especially in high performance areas, and decrease the production of unwanted surface static loads, from which contaminants can not be released. One possible solution is to change the electrical properties of the wire. However, attempts to decrease the accumulation of organic pigment on the development wire by changing its electrical properties can result in an interference with the function of the wire, and its ability to cause the formation of the pigment dust cloud organic. Therefore, there is a specific need for electrode members that have a decreased tendency to accumulate organic pigment, and also retain their electrical properties, to prevent interference with the operation thereof. There is an additional need for electrode members that have superior mechanical properties, including durability against severe wear that the electrode member receives when repeatedly brought into contact with the hard surfaces of the rotating dispensing member.

BRIEF DESCRIPTION OF THE INVENTION Examples of objects of the present invention include: It is an object of the present invention to provide an apparatus for reducing the accumulation of organic pigment on the electrode members in the development zone of a development unit in an electrophotographic printing apparatus, with Many of the advantages indicated in the present. Another object of the present invention is to provide an apparatus for reducing the adhesion of the organic pigment to the electrode members. It is another object of the present invention to provide an apparatus comprising electrode members having a lower surface energy. It is still another object of the present invention to provide an apparatus comprising electrode members having an increased mechanical strength. Still another object of the present invention is to provide an apparatus comprising electrode members having superior electrical properties. A further object of the present invention to provide an apparatus comprising electrode members having smooth surfaces. Many of the objects above have been achieved by the present invention, in the embodiments, which include: an apparatus for developing a recorded latent image on a surface, comprising: wire supports; a dispensing member, spaced from the surface and adapted to transport organic pigment to an opposite region of the surface; an electrode member, placed in the space between the surface and the dispensing member, the electrode member is very close to the dispensing member, and electrically polarized to separate organic pigment from the dispensing member, thereby allowing the formation of a cloud of organic pigment in the space between the electrode member and the surface, and the organic pigment separated from the organic pigment cloud develops the latent image, wherein regions of the opposite end of the electrode member are attached to wire supports adapted to support the regions of the electrode member. opposite end of the electrode member; and an inorganic coating on at least a portion of the unattached regions of the electrode member. The embodiments further include: an electrophotographic process comprising: a) forming an electrostatic latent image on a charge retentive surface; b) applying organic pigment in the form of a cloud of organic pigment to the latent image, to form an image developed on the retentive surface of charge, wherein the organic pigment is applied using a development apparatus comprising wire supports; a donor member spaced from the surface, and adapted to transport organic pigment to an opposite region of the surface; an electrode member, placed in the space between the surface and the dispensing member, the electrode member is very close to the dispensing member, and electrically polarized to separate organic pigment from the dispensing member, thereby allowing the formation of a cloud of organic pigment in the space between the electrode member and the surface, and the organic pigment separated from the organic pigment cloud develops the latent image, wherein regions of the opposite end of the electrode member are attached to wire supports adapted to support the regions of the electrode member. opposite end of the electrode member; and an inorganic coating on at least a portion of the unattached regions of the electrode member; c) transferring the organic pigment image from the charge retentive surface to a substrate; and d) fixing the organic pigment image to the substrate. The present invention provides electrode members which, in the embodiments, have a decreased tendency to accumulate organic pigment and which also, in the embodiments, retain their electrical properties to prevent interference with the operation thereof. The present invention further provides electrode members which, in embodiments, have superior mechanical properties, including durability against severe wear to the electrode member when repeatedly brought into contact with the hard surfaces of the dispensing-rhetor roller.

BRIEF DESCRIPTION OF THE DRAWINGS The above aspects of the present invention will become apparent where appropriate the following description with reference to the drawings, in which: Figure 1 is a schematic illustration of an embodiment of a development apparatus useful in an electrophotographic printing machine. Figure 2 is an enlarged schematic illustration of a dispensing roll and electrode member, representing an embodiment of the present invention. Figure 3 is a fragmentary schematic illustration of a development housing comprising a dispensing roller and an electrode member from a different angle than that shown in Figure 2. Figure 4 is an enlarged schematic illustration of an electrode member supported by mounting members in one embodiment of the present invention.

Figure 5 is an illustration of wire contamination and wire history.

DETAILED DESCRIPTION OF THE INVENTION For a general understanding of the aspects of the present invention, a description thereof will be made with reference to the drawings. Figure 1 shows a development apparatus used in an electrophotographic printing machine such as the one illustrated and described in US Patent No. 5,124,749, the disclosure of which is incorporated herein by reference in its entirety. This patent describes the details of the main components of an electrophotographic printing machine, and how these components interact. The present application will focus on the development unit of the electrophotographic printing machine. Specifically, after an electrostatic latent image has been recorded on a photoconductive surface, a band of the photoreceptor advances the latent image to the development station. At the development station, a development unit develops the latent image recorded on the photoconductive surface.

Referring now to Figure 1, in a preferred embodiment of the invention, the development unit 38 develops the latent image recorded on the surface photoconductor Preferably, the unit 38 of The development includes the dispensing roller 40 and the electrode member or members 42. The electrode members 42 are electrically polarized relative to the dispensing roller 40, to separate organic pigment therefrom, so as to form a cloud of organic pigment powder in the interval between the dispensing roller 40 and the surface photoconductor The latent image attracts organic pigment particles from the organic pigment dust cloud, forming an image of organic pigment powder on it. The dispensing roller is mounted, at least partially, in the chamber of the development housing 44. The camera in the development housing 44 ^? * stores a supply of development material. The development material is a two-component development material, of at least carrier granules having 20 particles of organic pigment that adhere triboelectrically thereto. A magnetic roller 46 disposed inside the chamber of the housing 44 guides the development material to the dispensing roller 40. The magnetic roller 46 is electrically polarized relative to the dispensing roller, so that * The organic pigment particles are attracted from the magnetic roller to the dispensing roller. More specifically, the development unit 38 includes a housing 44 defining a chamber 76, for storing a supply of two-component development material (organic pigment and carrier) therein. The dispensing roller 40, the electrode members 42 and the magnetic roller 46 are mounted in the chamber 76 of the housing 44. The dispensing roller can be rotated in any of the directions "with" or "against" relative to the direction of movement of the web 10. In Figure 1, the dispensing roller 40 is shown rotating in the direction of the arrow 68. Similarly, the roller magnetic can be rotated in any of the directions 'with' or 'against' relative to the direction of movement of the band 10. In Figure 1, the magnetic roller is shown rotating in the direction of arrow 92. The dispensing roller 40 is preferably made of aluminum anodized or ceramic. The development unit 38 also has electrode members 42, which are disposed in the space between the belt 10 and the dispensing roller 40. A pair of electrode members are shown extending in a direction substantially parallel to the longitudinal axis of the dispensing roller. The electrode members are made of one or more thin stainless steel or tungsten electrode members (ie, 50 to 100 μm in diameter) that are very close to the dispensing roll 40. The distance between the electrode members and the dispensing roller is from about 5 to about 35 μm, preferably from 10 to about 25 μm, or the thickness of the organic pigment layer on the dispensing roller. The electrode members are self-spaced from the dispensing roller by the thickness of the organic pigment that is on the dispensing roller. For this purpose, the ends of the electrode members supported by the upper parts of the end support blocks also support the dispensing roller for rotation. The ends of the electrode member are attached so that they are slightly above a tangent to the surface, including the organic pigment layer, of the structure of the dispenser. Mounting the electrode members in such a way makes them insensitive to roll runoff, due to their self-spacing. As illustrated in Figure 1, an alternative electrical polarization is applied to the electrode members by an AC voltage source 78. The AC * applied, which establishes an alternative electrostatic field between the electrode members and the dispensing roller is effective to separate organic pigment from the photoconductive member 5 of the dispensing roller, and form a cloud of organic pigment around the electrode members, the height of the cloud is such that it is not substantially in contact with band 10. The magnitude of the AC voltage is relatively low, and is in the order of 200 to 500 volts maximum, at a frequency in the range from about 9 kHz to about 15 kHz. A DC bias supply 80, which applies approximately 300 volts to the dispensing roller 40, establishes an electrostatic field between the photoconductive member of the web and the roller 40. , to attract the organic pigment particles separated from the cloud surrounding the electrode members to the latent image recorded on the photoconductive member. In a space in the interval from near 0. 01 μm to about 45 μ between the electrode members and the dispensing roller, an applied voltage of 200 to 500 volts produces a relatively large electrostatic field without risk of pneumatic interruption. A cleaning sheet 82 removes all the organic pigment from the dispensing roller 40 after development, so that the magnetic roller 46 meters fresh organic pigment into a clean dispensing roller. The magnetic roller 46 doses a constant amount of organic pigment, which has a substantially constant charge on the dispensing roller 40. This ensures that the dispensing roller supplies a constant amount of organic pigment that has a substantially constant charge in the development range. Instead of using a cleaning sheet, the combination of the spacing of the dispensing roller, ie the space between the dispensing roller and the magnetic roller, the height of the compressed pile of the development material on the magnetic roller, and the magnetic properties of the magnetic roller in conjunction with the use of a conductive magnetic developing material achieves the deposition of a constant amount of organic pigment that has a substantial charge on the dispensing roller. A DC bias supply 84, which applies approximately 100 volts to the dispensing roller 46, establishes an electrostatic field between the magnetic roller 46 and the dispensing roller 40, so that an electrostatic field is established between the dispensing roller and the magnetic roller, which causes organic pigment particles to be attracted from the magnetic roller to the dispensing roller. The dosing sheet 86 is positioned closely adjacent the magnetic roller 46, to maintain the height of the compressed stack of the development material on the magnetic roller 46 at the desired level. The magnetic roller 46 includes a non-magnetic tubular member 88, preferably made of aluminum, and having the outer circumferential surface thereof roughened. An elongated magneto 90 is positioned internally and spaced from the tubular member. The magnet is mounted stationary.

The tubular member rotates in the direction of the arrow 92, to advance the developing material adhering thereto, to the space defined by the dispensing roller 40 and the magnetic roller 46. The organic pigment particles are attracted from the carrier granules on the magnetic roller to the dispensing roller. With continuous reference to Figure 1, an endless screw, indicated generally by the reference number 94, is located in the chamber 76 of the housing 44. The worm 94 is mounted rotatably in the camera 76, to mix and transport the development material. The worm has knives that spiral outward from an axis. The knives are designed to advance the development material in the axial direction, substantially parallel # to the longitudinal axis of the shaft. When successive electrostatic latent images develop, the organic pigment particles within the development material are depleted. An organic pigment dispenser (not shown) stores a supply of organic pigment particles, which may include organic pigment and carrier particles. The organic pigment dispenser is in communication with the chamber 76 of the housing 44. When the concentration of organic pigment particles in the development material is decreased, fresh particles of organic pigment are delivered to the developing material in the chamber from the organic pigment dispenser. In a In the embodiment of the invention, the screw in the housing chamber mixes the new particles of organic pigment with the remaining development material, so that the resulting development material therein is substantially uniform with the concentration of particles of organic pigment that is being optimized. In this way, a substantially constant amount of organic pigment particles is in the chamber of the developing housing, and the organic pigment particles have a constant charge. The development material in the development housing camera is * Magnetic, and can be electrically conductive. By way of example, in an embodiment of the invention wherein the organic pigment includes carrier particles, the carrier granules include a ferromagnetic core having a thin layer of magnetite coated with a non-continuous layer of resinous material. The organic pigment particles can be made of a resinous material, such as a vinyl polymer, mixed with a coloring material, such as chromogenic black. The development material can comprise from about 90% to about 99% by weight of carrier, and from 10% to about 1% by weight of organic pigment. However, one skilled in the art will recognize that any other can be used suitable development material. In an alternative embodiment of the present invention, a one component development material, consisting of organic pigment without carrier can be used. In this configuration, the magnetic roller 46 is not present in the development housing. This embodiment is described in more detail in U.S. Patent No. 4,868,600, the description of which is incorporated herein by reference in its entirety.

One embodiment of the development unit is further represented in Figure 2. The development apparatus 34 comprises an electrode member 42, which is disposed in the space between the photoreceptor (not shown in Figure 2) and the dispensing roller 40. The electrode 42 may comprise one or more thin stainless steel or tungsten electrode members (ie, 50 to 100 μm in diameter) that are placed lightly on or near the dispensing structure. The electrode member is very close to the dispensing member. The distance between the wire (s) and the dispenser is from about 0.001 to about 45 μm, and preferably from about 10 to about 25 μm, or the thickness of the organic pigment layer 43 on the dispensing roller. The wires, as shown in Figure 2 are self-spaced from the dispensing structure by the thickness of the organic pigment that is on the dispensing structure. The extremities or regions of the opposite end of the electrode members are supported by support members 54, which can also support the dispensing structure for rotation. In a preferred embodiment, the extremities or regions of the opposite end of the electrode member are attached so that they are slightly below a tangent to the surface, including the organic pigment layer of the dispensing structure. Mounting the electrode members in such a manner makes them insensitive to roll runoff due to their self-spacing. In an alternative embodiment to that shown in Figure 1, the dosing sheet 86 is replaced by a dosing and combined loading sheet 86 as shown in Figure 3. The combination dosing and loading device can comprise any suitable device for deposit a well-loaded organic pigment monolayer on the dispensing structure. For example, it may comprise an apparatus such as that described in U.S. Patent No. 4,459,009, wherein the contact between the loosely charged organic pigment particles and a triboelectrically active coating contained on a charge roll results in a highly charged organic pigment. Another combination of dosing and loading devices may be employed, for example a conventional magnetic brush used with two-component development material could also be used to deposit the organic pigment layer on the dispensing structure, or a dispensing roller used only with the one component development material.

Figure 4 depicts an enlarged view of a preferred embodiment of the electrode member of the present invention. The electrode wires 45 are positioned within the electrode member 42. The fixation positions 55 of the electrode members are the portions of the electrode member that fix the electrode member to the support member. The mounting sections 56 of the electrode member are the sections of the electrode members between the electrode member and the means 54 of assembly. The organic pigment particles are attracted to the electrode members primarily through electrostatic attraction. The organic pigment particles adhere to the electrode members because the strength of The adhesion of the organic pigment is greater than the detachment force generated by the electric field of the electrode member. In general, the strength of adhesion between an organic pigment particle and an electrode member is represented by the general expression: Fad = q2 / kr2 + W, where F3d is the adhesion force, q is the charge on the organic pigment particle, k is the effective dielectric constant of the organic pigment and any dielectric coating, and r is the separation of the particle from its image charge inside the wire, which depends on the thickness, dielectric constant, and conductivity of the coating. The element W is the adhesion force due to the small interval adhesion forces, such as the van der Waals forces and the 5 capillaries. The force necessary to detach or remove particles from the electrode member is supplied by the electric field of the wire during the middle of its period of AC, qE, plus the effective forces resulting from the mechanical movement of the electrode member and the bombardment of the wire by the organic pigment that is in the cloud. Since the adhesion force is quadratic in q, the adhesion forces will be larger than the detachment forces for sufficiently high values of q. 15 Figure 5 contains an illustration of wire contamination and wire history. A photoreceptor 1 is placed near the wire 4, and contains an undeveloped image 6, which is subsequently developed by organic pigment originating from the dispensing member 3.

The contamination of the wire occurs when molten organic pigment 5 is formed between the wire 4 and the dispensing member 3. The problem is aggravated by fine dusts of the organic pigment and any components of the organic pigment, such as high molecular weight, crosslinked and / or branched components, and voltage interruption. * between the wire member and the dispensing roller. The history of the wire is a change in the capacity of development because the organic pigment 2 or 5 components of the organic pigment adhere to the upper part of the wire 4, the upper part of the wire is the part of the wire facing the photoreceptor. To prevent organic pigment defects associated with wire contamination and history of the wire, the electrical properties of the electrode member can be changed, thereby changing the adhesion forces in relation to the detachment forces. However, such changes in the electrical properties of the electrode member can adversely affect the ability of the electrode member to adequately provide a cloud of organic pigment, which is essential for developing a latent image. The present invention is directed to an apparatus for reducing unacceptable pigment accumulation Organic on the electrode member, while maintaining the desired electrical and mechanical properties of the electrode member. The electrode member of the present invention is coated with a coating of material that reduces the significant attraction of organic pigment particles to the electrode member, which can * result in accumulation of organic pigment. However, the coating of material does not adversely interfere with the mechanical or electrical properties of the electrode member. Materials that have these qualities include materials with low surface energy. The material with low surface energy decreases the accumulation of organic pigment ensuring continuity electric to load the wires, and eliminates the possibility of load accumulation. In addition, such low surface energy materials described herein do not interfere with the electrical properties of the electrode member, and do not adversely affect the ability of the electrode to produce a cloud of organic pigment powder. On the other hand, the electrode member maintains its mechanical properties of hardness, allowing the electrode member to remain durable against severe wear to the electrode member when This is repeatedly placed in contact with the surfaces of the hard and rotating dispensing roller. Also, the electrode member maintains a "smooth" surface after the coating is applied. A smooth surface includes surfaces that have a surface roughness of less than about 5 microns, * preferably from about 0.01 to about 1 miera. Examples of suitable low energy surface electrode coating materials include both organic materials and inorganic materials. It is preferred that the inorganic material possesses the characteristics of low surface energy, high hardness, very low or no porosity, smooth surface characteristics, low friction and high wear resistance, for allow the wire to withstand numerous cycles for everyday use in an electrophotographic apparatus. Examples of suitable inorganic materials that possess the above characteristics include ceramics, borosilicate glasses, diamond and similar compounds diamond, hard silicone coatings, molybdenum silicide, and derivatives thereof. Examples of ceramics that have little or no porosity include boron nitride, zirconium oxide, titanium carbide, silicon carbide, titanium nitride, diboride zirconium, yttrium oxide, glass ceramic (which has about 75 percent by weight of silica) and the like. Suitable ceramic coating materials are available as stable dispersions of ZYP Coatings Co. from Oak Ridge, Tennessee. Heat resistant glasses, such as, for example, borosilicate glass, also * are suitable inorganic materials, and have the characteristics above. Glass coated wires are commercially available from AMTX Company of 5 Canadaguia, NY, and from Pegasus of Springfield, MA. Diamond coatings and diamond derivatives, which include lower grade diamond, such as for example bort and carbon, are also suitable low surface energy and inorganic materials, and the commercially available examples include "Dylyn Coating" by Advanced Refractory Technologies of Buffalo, New York, which is a self-compensating interpenetrating network of carbon, hydrogen, silicon and oxygen. Another suitable low surface energy inorganic material is molybdenum silicide (MoSi2) and its combination with silica, both forms are commercially available as stable dispersions of ZYP Coatings Co. of Oak Ridge, Tennessee. Other suitable inorganic materials of low surface energy include silicone coatings Hardness such as, for example, silanes and siloxanes, which can be deposited on the surface of the wire by the method of Assisted Deposition by Ion Beam, thereby forming inorganic hard silicone coatings. The details of this technique are published in the Journal of Materials Research, Vol. 6, page 871, 1991, the description of which is incorporated herein by reference in its entirety. A filler, such as an electrically conductive filler, can be added to the coating of material in the amount from about 5 to about 35 percent by weight of the total solids, preferably from about 15 to about 20 percent by weight of total solids. The total solids herein include the amount of filler and inorganic solid material, catalyst, and any other additives. Examples of electrically conductive fillers include metal oxides such as tin oxide, titanium oxide, and zirconium oxide. Another preferred filler is carbon black, graphite or the like, with surface treatment of compounds such as, for example, siloxane, silane, fluorine or the like. Specifically preferred treated carbon blacks include fluorinated carbons such as those described in co-pending US Patent Application Serial Number 08 / 635,356, filed April 19, 1996, the disclosure of which is incorporated herein by reference. reference entirely.

The low inorganic coating material * surface energy is preferably present in an amount from about 5 to about 95 percent by weight of total solids, and preferably from about 10 to about 5 percent per weight of total solids. Total solids, as used herein, refers to the total amount by weight of inorganic coating material, fillers, and additives contained in the coating solution. The volume resistivity of the coated electrode is for example from about 10_1 ° to about 1_1 ohm-cm, and preferably from 10-5 to 10"1 ohm-cm The surface roughness is less than about 5 microns, and preferably from about 0.01 to about 1 mire 15. In a preferred embodiment of the invention, the coating material is deposited on at least a portion of the unattached regions of the electrode member.The unattached region of the electrode member is the entire outer surface region of the electrode minus the region wherein the electrode is attached to the mounting means 54, and minus the attachment area (55 in Figure 4). It is preferred that the coating cover the portion of the electrode member that is adjacent to the dispensing roller. In another preferred embodiment of the invention, the coating material is deposited in a complete area of the electrode member located in a central portion of the electrode member, and extending to an area adjacent to the non-attached portion of the electrode member. This area includes the entire surface of the electrode member minus the attachment area (55 in Figure 4). In an alternative embodiment, the entire length of the electrode member is coated with the coating material, including the fixing area 55 and the mounting area 56. In the embodiments, at least a portion refers to the unattached region that is being coated, or from about 10 to about 90 percent of the electrode member. The organic pigment can accumulate anywhere along the electrode member, but will not adversely affect the development, unless it accumulates in the length of the electrode member near the dispensing roll, or on the length closest to the photoreceptor . Therefore, it is preferred that the coating material cover the electrode member along the full length corresponding to the dispensing roll, and over the full length corresponding to the photoreceptor. The coating material can be deposited on at least a portion of the electrode member by any known suitable method. These deposition methods include liquid and powder coating, dip coating and spray coating, and ion beam and RF plasma assisted deposition. In a preferred deposition method, the deposition material is deposited on the electrode member by dip coating. With silicon materials, it is preferred to apply those coatings by ion beam assisted deposition. After coating, the inorganic coating is preferably air dried, and cured at a suitable temperature to cure the specific inorganic material. Curing temperatures are in the range from about 400 to about 1400 ° C, and preferably from about 600 to about 1200 ° C. The average thickness of the coating is from about 1 to about 30 μm thick, and preferably from about 2 to about 10 μm thick. If the coating is applied to only a portion of the electrode member, the thickness of the coating may or may not taper at the points furthest from the midpoint of the electrode member. Therefore, the thickness of the coating may decrease at the points furthest from the midpoint of the electrode. The electrode members of the present invention, the embodiments of which have been described herein exhibit superior efficiency in terms of wear resistance and decreased accumulation of organic pigment on the surface of the electrode member., while also maintaining its electrical properties, which stimulates the production of dust cloud development without accumulation of charge. In addition, the electrode members of the present exhibit superior mechanical properties, such as durability against the surfaces of the dispensing roll, which are normally made of hard materials such as ceramics. All patents and applications referred to herein are hereby specifically and fully incorporated herein by reference in their entirety to this specification. The following Examples define and further describe the embodiments of the present invention. Unless stated otherwise, all parts and percentages are by weight.

EXAMPLES # EXAMPLE 1 Preparation of the wire to be coated A stainless steel wire of about 76.2 microns 5 (3 mils) thick is preferably cleaned to remove obvious contaminants. An immersion coating apparatus with a cylinder of 2.54 cm (1 inch) (diameter) by 38.1 cm (15 inches) (in length) of glass, sealed in a The end for containing the liquid coating material can be used to dip the wire. A cable attached to an NSH-12R type motor from Bodine Electric Company is used to raise and lower a wire support carrier, which holds the wire taut during the process of coating. The speed of immersion and removal of the wire carrier in and out of the coating solution can be regulated by a B & motor controlled device. B Motors & Control Corporation, (control of NOVA PD DC motor speed). After the In the case of a coating, a motor-driven device is used to rotate the wire around its axis, while receiving external heating, to allow controlled evaporation of the solvent. When the coating is dry and / or non-fluid, the coated wire can be heated in a continuous flow oven using a program * of time and temperature to complete either the drying or curing / post curing of the coating. The general procedure may include: (A) cleaning and degreasing the wire with an appropriate solvent, for example acetone, alcohol or water, and roughened if necessary, for example, with sandpaper; (B) the coating material can be adjusted to the appropriate viscosity and solids content, adding solids or solvent to the solution; and (C) the wire is immersed and removed from the coating solution, dried and cured / post-cured, if necessary, and immersed again, if required. The thickness and uniformity of the coating are a function of the removal rate and viscosity of the solution, (solids content in most solvent-based systems) and a drying program consistent with the uniform solidification of the coating. EXAMPLES 20 Preparation of inorganic coating solutions EXAMPLE 1 A 76.2 microns (3 mils) thick stainless steel wire can be cleaned to remove obvious contaminants. A high purity titanium nitride (TiN) type "TN" dispersion, obtained from ZYP Coatings Inc., of Oak Ridge, TN, having 75% solids content in the immersion coater coating tank, is then added. . This coating can be applied using the conventional dip coating method described in Example 1. The coatings can then be air dried, and cured at 400 ° C for 12 hours. The resulting coating surface can then be polished by hand through a rubbing action, using a rubbing motion from back to front. EXAMPLE 2 A dispersion containing zirconium diboride, obtained from ZYP Coatings Inc., of Oak Ridge, TN as Type "ZB-MOD", having 58% solids content can be used as an inorganic coating solution. This coating can be applied using the conventional dip coating method described in Example 1. The coatings can then be air dried, and cured at 1,200-1,600 ° C. EXAMPLE 3 A dispersion containing molybdenum disilicide, obtained from ZYP Coatings Inc., of Oak Ridge, TN sold as Type "MS", which has about 50% solids content can be used as an inorganic coating. This coating can be applied using the conventional dip coating method described in Example 1. The coatings can then be air dried, and cured at 1,200-1,600 ° C. EXAMPLE 4 A dispersion of boron nitride, obtained from ZYP Coatings Inc., of Oak Ridge, TN sold as Type "BN-MOD", and which has about 25% solids content can be used as an inorganic coating. This coating can be applied using the conventional dip coating method described in Example 1. The coatings can then be air dried, and cured at 700-1,000 ° C. EXAMPLE 5 A dispersion of titanium carbide, obtained from ZYP Coatings Inc., of Oak Ridge, TN, sold as Type "T", which has about 45% solids content can be used as an inorganic coating. This coating can be applied using the conventional dip coating method described in Example 1. The coatings can then be air dried, and cured at 700-900 ° C.

EXAMPLE 6 A steel wire can be coated by Advanced Refractory Technology of Buffalo, NY, with a self-compensating interpenetrating network of carbon, hydrogen, silicon and oxygen, which is commercially available, called "Dylyn". The thickness of the coating is estimated to be from about 1 to about 3 microns, very smooth and relatively hard. The electrical conductivity is estimated to be about 10 ~ 3 ohm-cm. While the invention has been described in detail with reference to specific and preferred embodiments, it will be appreciated that various modifications and variations will be apparent to the skilled person. All modifications and modalities that may occur to a person skilled in the art are proposed to be within the scope of the appended claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (20)

1. CLAIMS 1. An apparatus for developing a recorded latent image on a surface, characterized in that it comprises: wire supports; a dispensing member, spaced from the surface and adapted to transport organic pigment to an opposite region of the surface; an electrode member, placed in the space between the surface and the dispensing member, the electrode member is very close to the dispensing member, and electrically polarized to separate organic pigment from the dispensing member, thereby allowing the formation of a cloud of organic pigment in the space between the electrode member and the surface, and the organic pigment separated from the organic pigment cloud develops the latent image, wherein regions of the opposite end of the electrode member are attached to wire supports adapted to support the regions of the electrode member. opposite end of the electrode member; and an inorganic coating on at least a portion of the unattached regions of the electrode member.
2. 2. An apparatus according to claim 1, characterized in that the inorganic coating comprises an inorganic material of low surface energy.
3. 3. An apparatus according to claim 2, characterized in that the low surface energy of the low surface energy material is from about 10 to about 25 dynes / cm.
4. 4. An apparatus according to claim 1, characterized in that the inorganic coating comprises a material selected from the group consisting of ceramic, borosilicate glass, diamond, M0S and derivatives thereof.
5. 5. An apparatus according to claim 4, characterized in that the inorganic coating is a ceramic material selected from the group consisting of boron nitride, zirconium oxide, titanium carbide, silicon carbide, titanium nitride, zirconium diboride and oxide from ytrio.
6. 6. An apparatus according to claim 3, characterized in that the inorganic coating is borosilicate glass.
7. 7. An apparatus according to claim 3, characterized in that the inorganic coating is selected from the group consisting of diamond and diamond derivatives.
8. 8. An apparatus according to claim 3, characterized in that the inorganic coating is molybdenum silicide.
9. 9. An apparatus according to claim 1, characterized in that the inorganic coating comprises an electrically conductive filler dispersed therein.
10. 10. An apparatus according to claim 9, characterized in that the electrically conductive filler is selected from the group consisting of carbon black, metal oxides, and metal hydroxides.
11. 11. An apparatus according to claim 10, characterized in that the conductive metal filler is selected from the group consisting of tin oxide, titanium oxide, zirconium oxide, 5 calcium hydroxide, and magnesium hydroxide.
12. 12. An apparatus according to claim 10, characterized in that the electrically conductive filler is carbon black.
13. 13. An apparatus according to claim 1, characterized in that the inorganic coating is present from about 10 to about 90 percent of the electrode member.
14. 14. An apparatus according to claim 1, characterized in that the inorganic coating is of a thickness from about 1 μm to about 5 μm.
15. 15. An apparatus according to claim 1, characterized in that the electrode member includes more than one thin diameter wire.
16. 16. An apparatus according to claim 1, characterized in that the thin diameter wires have a diameter from about 50 to about 100 μm.
17. 17. An apparatus according to claim 1, characterized in that the electrode member is very close to the dispensing member, a distance from about 0.001 to about 45 μm.
18. 18. An apparatus according to claim 1, characterized in that the material of the inorganic coating is deposited on the electrode wire by dip coating.
19. 19. An apparatus according to claim 18, characterized in that the inorganic coating material coated by immersion is cured at a temperature from about 400 to about 1,400 ° C.
20. 20. An electrophotographic process, characterized in that it comprises: a) forming an electrostatic latent image on a load retentive surface; b) applying organic pigment in the form of a cloud of organic pigment to the latent image, to form an image developed on the retentive surface of charge, wherein the organic pigment is applied using a development apparatus comprising wire supports; a donor member spaced from the surface, and adapted to transport organic pigment to an opposite region of the surface; an electrode member, placed in the space between the surface and the dispensing member, the electrode member is very close to the dispensing member, and electrically polarized to separate organic pigment from the dispensing member, thereby allowing the formation of a cloud of organic pigment in the space between the electrode member and the surface, and the organic pigment separated from the organic pigment cloud develops the latent image, wherein regions of the opposite end of the electrode member are attached to wire supports adapted to support the regions of the electrode member. opposite end of the electrode member; and an inorganic coating on at least a portion of the unattached regions of the electrode member; c) transferring the organic pigment image from the charge retentive surface to a substrate; and d) fixing the organic pigment image to the substrate.