US3815295A - Process for treating photoconductors - Google Patents

Process for treating photoconductors Download PDF

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Publication number
US3815295A
US3815295A US00168224A US16822471A US3815295A US 3815295 A US3815295 A US 3815295A US 00168224 A US00168224 A US 00168224A US 16822471 A US16822471 A US 16822471A US 3815295 A US3815295 A US 3815295A
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United States
Prior art keywords
layer
photoconductive layer
photoconductive
web
brush
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US00168224A
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English (en)
Inventor
W Lanker
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Turlabor AG
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Turlabor AG
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Priority to US00168224A priority Critical patent/US3815295A/en
Priority to IT27090/72A priority patent/IT962924B/it
Priority to NL7210017A priority patent/NL7210017A/xx
Priority to DE2236432A priority patent/DE2236432A1/de
Priority to CH1119372A priority patent/CH541161A/de
Priority to CA148,253A priority patent/CA982210A/en
Priority to GB3531772A priority patent/GB1397754A/en
Priority to BE786967A priority patent/BE786967A/xx
Priority to JP47077237A priority patent/JPS4825534A/ja
Priority to FR7227719A priority patent/FR2149814A5/fr
Priority to SE7209994A priority patent/SE381522B/sv
Priority to US465248A priority patent/US3910697A/en
Application granted granted Critical
Publication of US3815295A publication Critical patent/US3815295A/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/005—Materials for treating the recording members, e.g. for cleaning, reactivating, polishing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge

Definitions

  • the process of the present invention is especiallyuseful with layers containing organic materials and also when incorporated in an electrophotographic process which includes forrning a latent electrostatic image on a surface and transferring the latent electrostatic image from that surface.
  • Electrographic processes wherein a chargeable and selectively dischargeable layer is used and electropho tographic processes utilizing photoconductive layers which are chargeable and selectively dischargeable on exposure to a light image are well known to the art ln one type of process a photoconductive layer is coated on sheets of paper which are then used as the image forming surface in the process. A latent image formed on the surface can be developed to obtain'a visible copy.
  • the photoconductive layer is affixed to a cylindrical drum, a plate, or an endless belt and the layer is reused in producing successive copies. It is this second type of process to which the present invention is directed.
  • the photoconductive material comprising the photoconductive layer which was usually affixed to a metal cylinder or plate has been a relatively hard, inorganic material such as selenium or an alloy of selenium and one or more other metals. More recently organic photoconductive materials, characterized by a softer surface, have been used either alone or in composition as the photoconductive material in the photoconductive layers, which are affixed to cylinders, plates, or endless belts.
  • Commercial photocopying machines utilizing the electrophotographic process of the second type described above generally include developing a latent electrostatic image on the surface of the photoconductive layer followed by transferring the developed image to a support material such as a paper sheet.
  • This type of process will hereinafter be referred to as the developed image transfer process.
  • a large portion of the developer usually in powder form, is removed from the surface of the photoconductive layer, residual developer particles remain on the surface of the layer which must be cleaned to remove the residual developer particles before the photoconductive layer can be reused in producing subsequent copies.
  • the cleaning step required in the developed image transfer processes is eliminated in still another type of process, wherein the latent electrostatic image is formed and, without development of the latent image, the latent image is transferred from the surface of the photoconductive layer to a support surface.
  • the transferred latent electrostatic image on the support surface can be subsequently developed on the support surface to form the visible image.
  • developer particles do not contact the photoconductive layer.
  • This latter type of process which will hereinafter be referred to as the latent electrostatic image transfer process," is described in several patents including L. E. Walkup, US. Pat. No. 2,825,814. Although thenecessity of cleaning untransferred developing particles from the surface of the photoconductivelayer has been eliminated by this latter method. lint removing means can be'employed therewith, as disclosed by C. F. Carlson et al., in US. Pat. No. 3,015,304.
  • the latent electrostatic image transfer pro cess would be preferable over the developed image transfer processes, the latent electrostatic image transfer process has not as yet been commercially acceptable.
  • the quality of the copy obtained in repeated use of the photoconductive layer in both the developed image transfer process and the latent electrostatic image transfer process deteriorates in proportion to that use.
  • the deterioration in copy quality upon repeated use is especially pronounced with layers containing organic materials, particularly layers containing organic photoconductive material.
  • Organic photoconductive materials such as polyvinylcarba zole, have the advantages of low cost and relatively easy production as compared to inorganic photoconductive materials, such as selenium; but the deterioration as reflected in the deterioration in copy quality, upon repeated use, is greater with the former than with the latter.
  • the deterioration in copy quality can be related to the decrease in the surface potential, or saturation surface potential, also referred to as surface acceptance voltage or charge acceptance voltage; i.e., the maximum surface poten tial to which a layer can be charged, and in the decrease in the dark resistivity of the photoconductive layer upon repeated useof the layer.
  • the contrast of the image as determined'by the difference in potential between the unexposed and exposed areas of the image, decreases until thecontrast is insufficient to obtain a usable copy.
  • the saturation surface potential and the contrast potential, as well as the uniformity and constancy thereof, are generally referred to herein as the electrophotographic properties?
  • Another object of the present invention is to provide a treatment system which improves theelectrophotographic properties of a photoconductive layer which has been utilized in an electrographic process.
  • Another object of this invention is to provide for the regeneration of the electrophotographic properties of photoconductive layers comprising organic material which is susceptible to deterioration of its electrographic properties upon repeated use in an electrophotographic process.
  • the deterioration of the electrophotographic properties of the photoconductive layer is primarily a surface effect and that the desirable properties of the photoconductive layer can be regenerated by removing the particles of the layer which comprise the surface of the layer. Regeneration by this method is believed to be due to the elimination or substantial reduction of the charge injecting effect the deteriorated surface particles and moisture have upon the remainder of the layer, so as to restore and stabilize the electrophotographic properties of the layer.
  • surface particles as used herein and in the appended claims is intended to mean those particles of photoconductive material and other material, if any, which define the exposed surface of the photoconductive layer.
  • the surface particles of a photoconductive layer which has been used repeatedly in an electrophotographic process will commonly include decomposed, chemically changed layer material and external material from the surrounding atmosphere, such as water.
  • the surface particles may include decomposition products formed upon reaction of the exposed layer material with the surrounding atmo sphere.
  • particles underlying the surface particles may be removed along with the surface particles.
  • removal of such underlying particles particularly in the case of organic photoconductive material, organic binder materials, and organic overcoating layers, have been found to have no substantial deletorious effect upon the desirable properties of the layer.
  • the amount of material which can be removed in the regeneration process of the present invention is limited by the thickness of the photoconductive layer.
  • as little material as isnecessary for regeneration is removed from the layer, but up to about one-tenth to one-third of the thickness of the photoconductive layer, or 0.01 to about 1 mi-- cron as measured from the exposed surface of the layer toward the opposite surface of the layer, can be removed in the performance of the process of the present invention.
  • the layer should have a thickness substantially greater than the thickness of the material being removed during regeneration.
  • Photoconductive layers having a thickness of at least about 3 microns are preferred, and layers having a thickness above about microns are even more preferred in order to provide sufficient photoconductive material after regeneration for the production of copies of good quality.
  • the process of the present invention can be performed using a number of suitable devices.
  • One preferred embodiment of the present invention comprises abrading the layer to remove the surface particles.
  • the abrading can be effected in several ways.
  • One method is to contact the layer with an abrasive material such as oxides of the various metals, such as zinc, chromium. and aluminum, and some non-metals such as silicon, or the commercially available inert polishing powders.
  • the abrasive material has an average diameter less than about one micron.
  • the abrasive material is applied uniformly across the layer with a substantially constant pressure in order to substantially uniformly remove surface particles from the layer, at a small rate of abrasion, although uniform removal of the surface particles is not required to effect the regeneration.
  • the rate of abrasion is the thickness of material removed from the layer per number of cycles or copies. Removal of the surface particles is intended to mean separation of the particles from the remainder of the layer, and removal of these particles therefrom.
  • Contact of the abrasive material with the layer to obtain the separation and removal of particles can be performed by cascading the abrasive materials across the layer, by projecting the material against the layer under pressure, such as, air pressure, or by similar contacting methods.
  • inert abrasive material i.e., material which does not cause deterioration of the electrophotographic properties of the layer upon contact with the layer, on the surface of the photoconductive layer after regeneration is not detrimental to the use of the layer in an electrophotographic reproduction process.
  • the presence of such inert material on the layer may even be an advantage due to a screening effect which the abrasive particles have upon the layer. Such advantage can be noted by a reduction in overdevelopment of edges of images with less development within the edges of the images.
  • a particularly efficient method of contacting the layer with the abrasive material comprises supporting the abrasive material on a web and contacting, such as by rubbing, the web against the layer.
  • the abrasive material can be applied to the layer homogeneously and with a constant pressure, to separate surface particles of the layer from the remainder of the layer, and to remove the particles therefrom by movement of the web.
  • Abrasive materials which are substantially spherical, such as the polishing powders can be impregnated into the web, adhesively affixed to the web, or retained thereon by other means. Abrasive materials having diameters in the order of from about 0.l to about 1 micron are preferred.
  • Particularly suitable abrasive materials for use with webs as described herein are hard, inert inorganic materials, such as minerals and oxides, preferably aluminum oxide, zinc oxide, titanium dioxide,silicon dioxideor chromium oxide, and materials fibrous in shape, such as glass wool or asbestos.
  • the web material may comprise fibrous material, such as animal fur, natural fibers, such as cotton, wool, hair, cellulose, synthetic furs, paper or cloth ing small diameters, in the order of about one micron or less, in or on the web.
  • Particularly suitable abrasive materials are those having the shape of fibers or needles, which can be incorporated into the supporting web, such as by being woven therein, or can comprise the web itself.
  • a suitable web of this type is a soft paper web which contains fine glass fibers or other abrasive fibers-These webs can be contacted with the layer by the use of tensioning rollers or a support surface as will be hereinafter described. Only slight contact pressures, in the order of from about to about 100 grams per square centimeter have been found to be required when using the web materials described above, and the pressure may be decreased with increased abrasiveness of the web or the contact area.
  • the amount of particles and the depth to which particles are removed from the layer uponperforming the rege'ne'rationmethod of the present invention using a web as the abrasive surface or support can be controlled by adjusting the contact pressure of the web against the layer, as described above, by altering the abrasiveness of the web, e.g., by changing the nature or properties of the abrasive materials, or by altering the area of contact, as noted above, as well as by adjusting the proportion of abrasive material, the speed of the web relative to the layer, the frequency with which the web is replaced as it becomes less abrasive through use, and the interval and duration of contact of the material with the layer.
  • a second method of performing the abrading comprises contacting the photoconductive layer with a rotating brush.
  • the brush preferably comprises a plurality of bristles affixed to a shaft.
  • the shaft can be rotatably mounted adjacent the photoconductive layer with the axis of rotation eitherparallel, perpendicular, tangential, or at an angle to the surface of the layer, and rotated and contacted with the layer as desired.
  • the bristles of the brush can be formed of any suitable material such as the synthetic bristles, and preferably natural bristles; for example: animal fur, such as rabbit, fox, beaver, hair of cows ear; goat skin; horse hair; hogs bristles; mixtures thereof; and the like.
  • the brush used in the method of the present invention for removal of the surface particles can be very soft, for example,the animal furs, such as rabbit, fox, etc., or goatskin with photoconductive layers having organic material as their top surface; whereas brushes having bristles which have greater coarseness, hardness or stiffness must be used with the inorganic layer materials,
  • the bristles preferably have a diameter of from about 0.05 to about 0.3 millimeters, and the brush desirably has a diameterof from about to about 60 centimeters. It is preferred to contact the brush with the surface of the photoconductive layer with slight pressure in the order of about 100 grams per square centimeter.
  • Excellent results are obtained by periodically contacting the photoconductive layer with a brush as described above, whose axis of rotation is parallel to the surface of the layer, rotating at a speed of from about 1,000 to about 5,000 revolutions per minute.
  • the brush can be contacted with the layer after each electro'photographic cycle, it is preferred, especially at relative humidities above about 40 percent, to contact the layer with the brush less frequently; for example, in the order of once every 10, 100, 1,000 or 10,000 cycles.
  • the latter embodiment permits the use of brushesof greater stiffness having advantage at higher relative humidities, for example. above about 40 percent.
  • a second embodiment of the method of the present invention for regenerating a photoconductive layer by removing surface particles comprises washing or wetting the surface of the layer with a solvent.
  • the solvent may be applied to the layer by movingthe layer through a body of the solvent or by flowing the solvent over the layer.
  • a fibrous web can be wetted with the solvent and the web then contacted with the layer in a manner similar to the application of a web supporting or containing an abrasive material to the layer. Washing the layer can also be advantageous when combined with another regeneration method, such as heretofore described, to further assist in removing, as by washing, separated particles and/0r abrasive material from the surface of the layer.
  • the photoconductive layer preferably is removed from contact with the solvent or other liquids when the layer is not being utilized for its intended function, as when electrophotographic copying using the layer has ceased.
  • FIG. 1 is a schematic illustration of means for regenerating a photoconductive layer according to one embodiment of this invention.
  • FIG. 2 is a schematic illustration of means for regenerating a photoconductive layer according to another embodiment of this invention.
  • FIG. 3 is also a schematic illustration of apparatus for regenerating a photoconductive layer according to still another embodiment of this invention.
  • FIG. 4 is a schematic illustration of a modification of the embodiment of the present invention schematically illustrated in FIG. 1.
  • the photoconductive layer may contain any suitable photoconductive material such as selenium, cadmium sulfide, or any of the organic photoconductors known to the art, such as polyvinylcarbazole, or any of the copolymers or derivatives thereof.
  • the photoconductive layer may consist only of the photoconductive material or may contain organic material, for example, a binder material such as an organic resin, or a top surface material, preferably of organic material, and preferably the top surface material is at the surface of the photoconductive layer, or other materials, and may contain one or more sensitizing dyes.
  • the top surface layer in or on photoconductive layer 12 may be treated in the same manner as the pho toconductive layer.
  • a latent electrostatic image is formed on the surface of the photoconductive layer 12 by means of applying a uniform charge to the photoconductive layer 12 and exposing the charged layer to a light pattern to selectively dissipate the charge on the layer 12 in accordance with the light pattern.
  • corona unit 16 includes one or more thin charging wires 18 surrounded by a conductive shield 20.
  • a power supply such as DC. source 22 is connected to the charging wires 18 and is also connected to the conductive inner surface 14 supporting the outer layer 12 of photoconductive insulating material by known means such as a direct connection (not shown) or through ground. The connection between the conductive inner surface 14 and the power source 22 is completed in the embodiment of FIG.
  • the step of exposing the photoconductive layer 12 bearing a uniform charge on its surface to a light pattern is performed by means of an illumination and projection system 28 comprising at least one illumination source 30 mounted in a suitable reflector 32 and a lens 34.
  • an original document 36 to be copied is transported by means (not shown) known to the art through the exposure station wherein light from the illumination source 30 and/or light reflected from the reflector 32 illuminates the surface of document 36 to be copied and the light rays are reflected through lens 34 onto the surface of photoconductive layer 12.
  • the light rays from illumination source 30 and/or reflector'32 are reflected from the document 36 in varying intensity according to the absorption of the rays by the surface of document 36 bearing a visible image.
  • the resultant reflected rays form a light pattern corresponding to the visible image on the document 36.
  • the rays comprising the light pattern are projected by lens 34 onto the surface of the photoconductive layer 12 where they selectively discharge the uniform charge on the surface of photoconductive layer 12 in accordance with the intensity of the reflected rays.
  • rays of relatively high intensity being reflected from white or light, usually background, areas of the visible.
  • image on document 36 cause the discharge of the uniform charge on the photoconductive layer 12; whereas rays of low intensity reflected from darker areas of the document or the absence of rays due to total absorption of the illuminated rays from source 30 and/or reflector 32, do not discharge the uniform charge or discharge the uniform charge on photoconductive layer 12 to a lesser extent in accordance with the photoconductive properties of the layer.
  • the uniform charge applied to the photoconductive layer 12 by-corona unit 16 is selectively discharged or dissipated to form a latent elect rostatic image on the surface of the photoconductive layer 12.
  • the latent electrostatic image on the surface of photoconductive layer 12 can be utilized in several manners known to the art. As heretofor described, the latent electrostatic image on the surface of photoconductive layer 12 can be developed by various means known to the art and the developed image transferred to a re DCving sheet or other suitable surface. The transferred developed image can then be fixed on the receiving surface by suitable means such as the application of infrared rays. The surface of photoconductive layer 12 after the transfer step can then be cleaned as known to the art, and reused in the next cycle of the apparatus.
  • the process of the present invention is especially useful in the latent electrostatic image transfer process, such as the process utilized by the apparatus shown in FIG. 1.
  • the latent electrostatic image on the surface of photoconductive layer 12 is transferred by means of transfer apparatus 38 to a transfer sheet, such as sheet 40,'which may be a sheet having a dielectric coating.
  • Sheet 40 is fed from a stack a resistance greater than that of the photoconductive layer 12.
  • the latent electrostatic image on the photoconductive layer 12 is transferred to the sheet 40 by means known to the art and preferably by the application of a field.
  • the field is applied by means of a transfer corona unit 56 consisting of at least one corona discharge wire 58 partially surrounded by a conductive shield60.
  • a potential is applied to corona discharge wire 58 'by means of a source of potential 62 which in turn is also connected to the conductive inner surface 14 of drum 10 by direct connection (not shown) or through ground and contact 24 and shaft 26.
  • the potential required for transfer of the latent electrostatic image is known to'the art from various patents, such as U.S. Pat. No. 2,825,814 heretofore described.
  • the receiver sheet 40 is conveyed by conveyor 52 along a second path 64 to a developing station 66.
  • the developing station 66 shown in FIG. 1 comprises a tank or tray 68 containing a liquid developer 70 as known to the art, such as liquid toner disclosed in Wagner U.S.
  • the liquid developer 70 is applied to the receiver sheet 40 by immersing the sheet in liquid developer 70 by guiding the sheet along a partially submerged guiding member 72.
  • Sheet 40 is removed from developing station 66 by the leading edge of the sheet contacting a pair of rollers 74 which advances the sheet along second path 64.
  • Sheet 40 next reaches drying station 76 wherein the developed image on the sheet is fixed to the sheet by evaporating liquid compo nents of liquid developer 70 and preferably by heating and fusingdeveloper from liquid developer on and in the surface of the sheet.
  • the drying station 76 can consist of infrared sources 78 mounted in a reflecting shield 80. Sheet 40 is next exited from second path 64 into a receiving tray 82.
  • any charges remaining on photoconductive layer 12 l are discharged by means of a light source 84 mounted adjacent the surface of photoconductive layer 12 in a reflecting light shield 86 subsequent along the direction of rotation of drum to the developing station 56.
  • the spectrum of light source 84 desirably corresponds to the spectrum of the photoconductive material in photoconductive layer 12.
  • the apparatus of the present invention is shown therein as a brush 87 mounted to be contactable with the surface of photoconductive layer 12.
  • Brush 87 comprises a plurality of bristles 88 .mounted on a shaft 89.
  • the brush 87 can be permanently mounted in contact with photoconductive layer 12, thus effecting regeneration of the photoconductive layer 12 upon each cycle of the layer 12 through the various steps within the electrophotographic process, or, as shown, can be spaced apart from contact with the photoconductive layer 12, but mounted so as to be selectively contactable with the layer.
  • brush 87 can be mounted on a member 90 pivoted by a shaft 92 by a solenoid plunger 94.
  • switch 95 when switch 95 is closed, an electrical circuit is completed connecting electrical source 96 to solenoid coil 98 causing solenoid plunger 94 to force member 90 to pivot about shaft 92 so that brush 87 is placed into contact with the surface of photoconductive layer 12.
  • switch 95 Upon opening switch 95, the connection of source 96 to solenoid coil 98is broken, releasing solenoid plunger 94 from member 90.
  • Brush 87 is withdrawn from contact with photoconductive layer 12 by means of spring 100 affixed to member 90 and on the other side to frame 102 of the apparatus, causing brush 87 to be withdrawn from contact with the photoconductive layer 12.
  • switch 95 can be periodically closed to cause brush 87 to be periodically contacted with the surface of photoconductive layer 12 for regenerating the photoconductive properties of the layer.
  • Switch 87 can be replaced by suitable automatic means, such as an automatic counter, so as to complete the circuit periodically, for example after a predeterminednumber of cycles, e.g. revolutions of drum 10, or after a predetermined number of receiving sheets have been processed through the apparatus.
  • suitable automatic means such as an automatic counter
  • FIG. 2 another embodiment of apparatus according to the present invention is illustrated, wherein-elements similar to elements in FIG. 1 have the same ref erence numerals.
  • the cylindrical drum 10 provided with an outer photoconductive layer 12 is constructed and arranged in the same manner as in the case of the embodiment shown in FIG. 1.
  • charging unit 16 and the illumination and projection system 28 as well as the light source 84 and reflector 86 for discharging residual charges on the surface of photoconductive layer 12 correspond with the appropriate apparatus of FIG. 1 and are referenced in the same manner so that a repeated description is unnecessary.
  • a web 120 of receiving material is supplied from a roll of web ma terial 122 and is applied in intimate contact with the photoconductive layer 12 by means of rollers 124 and 126.
  • Suitable tensioning apparatus (not shown) can be included to maintain contact of the web 120 against the photoconductive layer 12.
  • the latent electrostatic image on the surface of photoconductive layer 12 formed by means of the corona unit 16 and the illumination and projection system 28 is transferred from the surface of the photoconductive layer 12 to the'receiving web 120' by the application of a field by means of corona discharge unit 128.
  • Discharge unit 128 comprises at least one corona discharge wire 130 partially surrounded by a conductive shield 132.
  • the corona discharge is effected by connecting a source of potential 134 to corona discharge wire 130 with the other terminal of source 134 being connected to the conductive inner surface 14 of drum 10 either by direct connection (not shown) or through ground and contact 24 and shaft 26.
  • a developing station 136 comprising, in this embodiment, a tank 138 containing solid, powdered toner 140 which is known for use in developing latent electrostatic images.
  • a magnetic brush 142 comprising magnets mounted about a common axis and particles of material attracted by the magnet which carry the toner particles by magnetic attraction from the tank 138 to the said surface of web 120.
  • Magnetic brushes of various types are know and can be utilized in this embodiment of the present invention.
  • the web is advanced past a fixing station 144 generally similar to drying station 76 of FIG. 1.
  • Fixing station 144 comprises one or more infrared heating elements 146 partially surrounded by a reflective shield 148.
  • the visible image on the web resulting from the development of the transferred latent electrostatic image at developing station 136 is fused and bonded to the surface of the receiving web 120.
  • the receiving web 120 is collected on a take-up roll 150.
  • Web 120 may be advanced by driving take'up roll 150 synchronously with the rotation of drum l0. 1
  • the photoconductive layer 12 is rotated on drum 10 past illumination source and reflector and light shield 86 to discharge any charges remaining on the surface of photoconductive layer 12 to washing station 152. Washing'station 152.
  • photoconductive layer 12 is regenerated by removing surface particles of the layer by washing the layer with a solvent, i.e., a liquid which is a solvent for the surface particles, preferably selectively a solvent for decomposed material, moisture, and
  • a solvent i.e., a liquid which is a solvent for the surface particles, preferably selectively a solvent for decomposed material, moisture, and
  • photoconductive layer 12 is rotated through a body of a liquid 154, which can be a solvent, for the particles comprising the surface of photoconductive layer 12.
  • ethanol has been found to be a suitable solvent for surface particles thereof.
  • the liquid 154 preferably is a poor solvent for undeteriorated material in the photoconductive layer 12.
  • the washing action can be effectively attained by combining the washing with another method for removing surface particles of the layer, such as those described hereinv
  • the washing station further preferably includes a body of solid material 156 which contacts the surface of layer 12 and the liquid 154.
  • Solid material 156 may be in the form of a sponge or folded or thick cloth (not shown) and preferably may be abrasive to layer 12 so as to remove surface particles from layer 12 by abrading the layer in the presence of liquid 154.
  • the liquid 154 may be a very poor solvent for layer 12, but will assist the removal of surface particles, as by washing separated particles from the surface of layer 12.
  • the photoconductive layer 12 is contacted with both the solid material 156 and the liquid 154 to remove, by abrading and washing and/or by dissolving, the surface particles from the layer.
  • Other surface particle removing means such as a web of paper or cloth or a brush, may be substituted for the solid material 156 to effect the abrading and washing operations.
  • FIG. 3 A further embodiment of apparatus according to the present invention is illustrated in FIG. 3, wherein elements similar to elements in FIGS. 1 and 2 likewise have the same reference numerals.
  • the washing station 152 of FIG. 2 is replaced with a web contacting station 160.
  • Web contacting station 160 comprises a web 162 and roller 164 which maintains contact of the web with the surface of photoconductive layer 12.
  • Web 162 is supplied from supply roll 166, is advanced by the roller 164 toward and away from the surface of photoconductive layer 12, and is gathered by suitable means (not shown) onto a take-up roll 168.
  • a latent electrostatic image is formed on the surface of photoconductive layer 12 by first applying a uniform charge to the layer by use of corona unit 16 and byselectively discharging the uniform charge on the surface of photoconductive layer 12 by means of illumination and projection system 28.
  • the latent electrostatic image is next transferred to a receiving web 120 by means of transfer corona unit 128. Residual charges on the surface of photoconductive layer 12 are discharged by illumination source 84 and reflector light shield 86. Surface particles of the photoconductive layer 12 are removed therefrom by means of web contact station 160 to regenerate the photoconductive layer 12 for use in the next cycle of the apparatus in accordance with this invention.
  • the web 162 desirably supports abrasive material on its surface and is contacted with the surface of photoconductive layer 12 by means of roller 164 providing support to the back of web 162, and maintaining the web against the layer 12, thereby abrading photoconductive layer 12 to remove the surface particles therefrom.
  • Gently abrading action can be obtained by advancing the web 162 in the direction of, and at the peripheral speed of the rotation of photoconductive layer 12.
  • Increased abrasive action can be obtained by advancing web 162 in the same direction as the direction of rotation of photoconductive layer 12 at a speed substantially greater than the peripheral speed of photoconductive layer 12, or by advancing the web in the same direction as the direction of rotation of photoconductive layer 12, but at a speed less than the peripheral speed of the photoconductive layer. Further increased abrasive action can be obtained by advancing the web at reduced speeds, by stopping the web during the regeneration step, or by advancing the web'in a direction opposite to the direction of rotation of photoconductive layer 12.
  • the amount of abrasion can also be controlled by adjusting the pressure that the roller 164 exerts on the back of web 162 to provide increased or decreased pressure of the web 162 against the photoconductive layer 12.
  • the severity of abrasion can readily be controlled in accordance with the amount of material, i.e., surface particles and particles thereunder to be removed, and in accordance with the abrasiveness of the material on the surface of web 162.
  • web 162 can desirably be a web which is itself abrasive.
  • a very suitable web 162 was prepared of paper containing fine glass fibers as the abrasive. The preparation of the web will be hereinafter described.
  • FIG. 4 a modification of the apparatus illustrated in FIG. 1 is schematically illustrated, wherein elements similar to elements in FIG. 1 have the same reference numerals. The function of these similar elements and the formation and transfer of the image have been described heretofore.
  • the photoconductive layer 12 is rotated on drum 10 past illumination source 84 and reflector and light shield 86, to discharge any charges remaining on the surface of layer 12, to brushing unit 170.
  • Brushing unit can com prise a generally circular brush 172 formed of bristles affixed to a shaft 174, which rotatably supports brush 172 at an angle to the surface of photoconductive layer 12.
  • the brush is supported at a large angle,-
  • Shaft 174 supporting brush 172 can be rotated by suitable means, such as a motor 176 which in turn may be guidingly supported upon a guiding member 178, which advantageously may be a rack, by a bracket which may include a pinion.
  • brush 172 is moved parallel to the axis of shaft 26 of drum l0 and hence the surface of layer 12 by known means (Not shown) during operation sothat the entire surface of photoconductive layer 12 is uniformly contacted with the brush during the process of the present invention. Movement in this manner can be accomplished by reciprocally moving motor 176 which supports shaft 174 and brush 172 along guiding member 178 which can be mounted parallel to the axis of shaft 26.
  • Brush 172 may be rotated at any desired speed, and preferably the brush is rotated rapidly, for example at speeds in the order of 10,000 to 20,000 revolutions per minute.
  • the pressure at which the brush contacts layer 12 can be varied, but small pressures, in the order of 50 to 100 grams over a small area such as 0.2 square millimeters, are preferred.
  • the brush desirably has a diameter of from 10 to 20 millimeters com prising bristles having a diameter of from 0.1 to 0.2 millimeters, although harder or softer brushes can be used.
  • the regeneration step may be performed at every cycle of the drum 10, or preferably periodically at intervals, such as at every 10, 100, 1,000 10,000 imaging cycles of the drum.
  • Example A comparative test was conducted with apparatus similar to the apparatus illustrated in FIG. 1.
  • Photoconductive Luvican M470 obtainedv from Badische Anilin-Soda Fabrik, Germany, polyvinylcarbazole, mixed with 3 percent tetranitrofluorenone and 20 percent plasticizer, Dowtherm A obtained from Fluka A.G., Buchs, Switzerland, was coated to a thickness of from 5 to 6 microns on aluminum foil.
  • the coated foil was taped onto an aluminum 'drum so that the underside of the foil was in electrical contact with the drum.
  • the coated foil was charged using a corona unit having an applied voltage of minus 10 kilovolts, direct current.
  • the coated foil was exposed to image-wise incandescent light at an exposure of l 14 lux-seconds.
  • the latent electrostatic image formed was transferred after a predetermined number n of charging anddischarging cycles ofv the drum.
  • the latent electrostatic images were discharged with a incandescent discharge lamp prior to formation of the subsequent image.
  • transfer of the latent electrostatic image to a sheet of dielectric paper supported on a metal drum across an air-gap of about 60 microns was effected with the use of a transfer voltage of about 130 volts D.C. applied across the drums supporting the respective surfaces.
  • the drum supporting the photoconductive surface was revolved at a speed of revolutions per minute and the second drum also revolved at the same speed.
  • the relative humidity during the test was approximately 50 percent.
  • the transferred latent image was developed with liquid toner, commercially available from SCM Corporation,
  • Example 2 Example 1 was repeated, except that a brush of goatskin having a diameter of about millimeters rotating at about 1,200 revolutions per minute was utilized at percent relative humidity in place of the synthetic bristle brush. Copies of relatively good quality were obtained after2,000 imaging cycles where the brush was contacted with the drum at each cycle, as compared to copies obtained without the application of the brush;
  • the regeneration effect was obtained by the application of other brushes of goatskimhorse hair, and synthetic bristles rotating at from 1,000 to 5,000 revolutions per minute at cycling intervals of from every imaging cycle to once every 1,000 imaging cycles with the photoconductive layer described in Example 1.
  • Example 3 Apparatus similar to that illustrated in FIG. 3 including a metal drum coated with the photoconductive layer defined in Example 1 was utilized in this example.
  • Paper webs were prepared by disintegrating tissue paper,'Linsoft, obtained commercially from Migros Co., Switzerland, into water by soaking the paper therein and adding glass woolhaving a fiber diameter of about 5 to 20 micronsin predetermined amounts. The suspension was mixed and dried. Upon drying, soft paper webs of about micron thickness containing predetermined amounts of glass wool were obtained.
  • the drum described above supporting the photoconductive layer was rotated with a web prepared as above containing 20 percent by weight glass wool and having a relatively rough surface pressed against the layer by a roller having about 10 millimeters of soft sponge rubber as its surface with a pressure of 50 grams per square centimeter, over a contact area as wide as the photoconductive layer and having a length of 2 centimeters.
  • abrasion rate 1 micron per 1,000 cycles.
  • the abrasion rate was found to increase about linearly from 2 to about 40 percent glass wool with increased proportions of glass wool in the web, and converselythe abrasion rate decreased as the proportion of glass wool in the web decreased.
  • the abrasion rate increased with increasing pressure applied to the web against the drum and decreased with decreasing pressure.
  • the electrophotographic properties of the layer as evidenced by the saturation surface voltage, were regenerated to commercially acceptable levels in this example even at high relative humidity. For example, after 1,000 cycles at 70 percent relative humidity, with the paper web contacting the layer at every cycle, the saturation surface voltage measured as in Example 1, was 70 percent of the voltage measured at the first cycle; whereas without the use of the paper web, the voltage measured zero percent of the voltage at the first cycle.
  • Example 4 The abrasion rate of one micron per. 1,000 cycles ob tained in Example 3 was found to be a limiting factor if regeneration of the photoconductive layer is to take place at each photocopy cycle or at some small number of photocopy cycles. Therefore, an abrasion rate of from about 0.01 to about 0.1 micron per 1,000 cycles is obtained by preparing, in the manner described above, paper webs having a thickness of about 50 to about 100 microns (about 1530 grams per square meter) containing from about 1 to about 10 percent, and preferably 5 percent, glass wool having a fiber diameter of less than 5 microns preferably less than about 2 microns.
  • These webs are contacted with the surface of the photoconductive layer at a pressure of from about to about 30 grams-per square centimeter to obtain the desired abrasion rate upon continuous contact.
  • Regeneration of the photoconductive layer upon use in an electrophotographic process accomplished by applying the web to the surface of the layer periodically, for example, once every 10 to 100 cycles of the electrophotographic process, also reduces the abrasion rate.
  • the photoconductive layer can be utilized in from 10,000 to 100,000 electrophotographic cycles per 1 micron in thickness of the photoconductive layer until the layer becomes too thin to provide an electrostatic image which is acceptable upon development and preferably upon transfer and development.
  • the paper web can be advanced past the area of contact with the photoconductive layer at a speed in the order of 0.1 to 1 meter per 1,000 regeneration cycles.
  • Example 5 A web of tissue paper, prepared from Linsoft,” obtained from the Migros Co., Switzerland, whose surface was covered with approximately 01 l-0.2 milligrams per square centimeter of aluminum oxide powder, having a diameter of approcimately 0.05 micron was used in this example with apparatus similar to that illustrated in FIG. 3. Upon contact of the powder covered paper web to the surface of the photoconductive layer, controlled removal of surface particles of the photoconductive layer was obtained. The contact of the web to the layer was made with a pressure of approximately -100 grams per square centimeter applied to the web.
  • the saturation surface voltage measured as described in Example 1 was 60 percent of the voltage at the first cycle. Where the web was not used, i.e., no regeneration step after 1,200 imaging cycles, the voltage measured was 20 percent of the voltage at the first cycle.
  • Example 6 Example 5 was repeated using paper webs as described in Example 4, covered with similar amounts of polycrystalline zinc oxide. These webs, when applied to the surface of the photoconductive drum under the same conditions of applied pressure and relative humidity, abraded the surface of the photoconductive layer to remove surface particles and thereby provide regeneration of the photoconductive layer. For example, after 10,000 imaging cycles including 200 cycles where the web was applied, the saturation surface voltage, measured as in Example 1, was 50 percent of the voltage at the first cycle. Where the web was not utilized, after 10,000 imaging cycles the voltage was zero percent of the voltage at the first cycle.
  • Example 7 The photoconductive layer described in Example 1 was placed on a metal drum in the manner described therein surrounded with the charging, voltage measuring, imaging and discharging apparatus described in that example.
  • the brush apparatus in Example 1 was replaced with a tubular infrared lamp of about watts mounted in a cylindrical mirrored reflector mounted adjacent the surface of the photoconductive layer so as to heat the said surface to a temperature of from about 120 to about centigrade.
  • AFter 10,000 imaging cycles at a relative humidity of 50 percent with the infrared lamp heating the layer at each cycle the saturation surface voltage was measured as in Example 1 and found to be 70 percent of the voltage at the first cycle. However, after 10,000 imaging cycles under the same conditions without the use of the infrared lamp, the saturation surface voltage was zero percent of the voltage at the first cycle.
  • Example 8 A photoconductive layer on a metal drum as described in the previous example was similarly surrounded with the charging, measuring, imaging and discharging apparatus described in Example 1.
  • the regeneration step of the present invention when used, was effected by contacting the layer lightly with facial tissue paper, Linsoft commercially obtained from the Migros Co., Switzerland, wetted with ethanol. After 10,000 imaging cycles at 50 percent, relative humidity, with the application of the ethanolwetted tissue paper for 100 cycles, the saturation surface voltage was 50 percent of the voltage at the first cycle; whereas after the same number of imaging cycles withoutthe use of the wetted tissue, the saturation surface voltage was zero percent of the voltage at the first cycle.
  • Example 9 Apparatus similar to the apparatus described in FIG. 4 was utilized in this example.
  • Various photoconductive layers were coated on aluminum foil and the foil affixed to a metal drum.
  • the charging, voltage measuring, imaging and discharging apparatus described in the previous examples was utilized withthe drum under the conditions hereinafter described.
  • the regeneration step was performed using the following motor driven brush: Moto-tool, model no. 2, kit 1, brush no. A-3, obtained from Dremel Manufacturing Co., Wisconsin, U.S;A., the bursh having a diameter of 18 millimeters and a bristle thickness of 0.2 millimeters, mounted as shown in FIG. 4, with the bristles being at an angle of between about 30 and about 40 to the tangent of the layer at the point of contact.
  • the apparatus applied the bristles of the brush to the layer with a'pressure of approximately 80 grams over the limited area of contact while at rest.
  • the brush was rotated at from about 10,000 to about 20,000 revolutions per minute for about 0.01 to about 0.02 second at each portion of the layer per cycle of the drum.
  • the saturation surface voltage was from 40 to 50 percent of the voltage at the first cycle; while after the application of the brush at each 6,000th cycle, the saturation surface voltage was from 65 to 80 percent of the voltage at the first cycle.
  • the deterioration effect i.e., the decrease of the charge acceptance of the layer and, hence, the contrast voltage of the latent electrostatic image, with increasing humidity, was found, particularly with organic photoconductors, such as polyvinylcarbazole, to depend primarily upon the relative humidity and only slightly, if at all, upon the absolute humidity.
  • the method of the present invention has been found to be effective in regenerating the electro photographic properties of the photoconductive layer to a considerable extent at low relative humidities, e.g., below about 40 percent relative humidity, and ma somewhat lesser extent at higher relative humidities.
  • Good regeneration can be obtained according to this invention at higher relative humidities, such as at to percent or higher relative humidity, by using relatively hard brushes, e.g., the brush of Example 9 periodically at every 10th, th or 1,000th cycle, or by using abrasive webs, such as that described in Example 3 at every cycle or at every 10th, 100th or 1,000th cycle.
  • Example 10 Example 10 was repeated without producing copies with the addition of a l volt, 150 watt infrared lamp supplied with 60 volts of potential placed adjacent the drum and partially surrounded by a cylindrical r'nirrored reflector so as to heat the'surface of the photoconductive layer to a temperature in the order of about 100 C at the area of contact of the layer by the rotating brush.
  • a l volt, 150 watt infrared lamp supplied with 60 volts of potential placed adjacent the drum and partially surrounded by a cylindrical r'nirrored reflector so as to heat the'surface of the photoconductive layer to a temperature in the order of about 100 C at the area of contact of the layer by the rotating brush.
  • the application of heat alone has the benefrcial effect of at least partially regenerating the desirable properties of the photoconductive layer by removing surface particles therefrom by evaporation, as illustrated in Example 7 herein, as well as to decrease the relative humidity of the atmosphere adjacent the layer to permit the other embodiments of the present invention to regenerate the desirable properties of the photoconductive layer to a greater extent at the higher relative humidity.
  • a process for regenerating a photoconductive layer which has been utilized in an electrophotographic process comprising removing surface particles of the photoconductive layer comprising materials of the photoconductive layer from the remainder of the layer.
  • a process for regenerating a photoconductive layer which has been utilized in an electrophotographic process comprising removing surface particles of the photoconductive layer comprising material of the photoconductive layer from the remainder of the layer, wherein the said removing comprises abrading the said layer to remove the said surface particles.
  • a process for regenerating a photoconductive layer which has been utilized in an electrophotographic process comprising removing surface particles of the photoconductive layer comprising material of the photoconductive layer from the remainder of the layer. said removing comprising abrading by contacting the said layer with an abrasive material to remove the said surface particles.
  • a process for regenerating a photoconductive layer which has been utilized in an electrophotographic process comprising removing surface particles of the photoconductive layer comprising material of the photoconductive layer from the remainder of the layer, said removing comprising abrading by contacting the said layer with a rotating brush to remove the said surface particles.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
US00168224A 1971-08-02 1971-08-02 Process for treating photoconductors Expired - Lifetime US3815295A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US00168224A US3815295A (en) 1971-08-02 1971-08-02 Process for treating photoconductors
IT27090/72A IT962924B (it) 1971-08-02 1972-07-17 Procedimento e apparecchiatura per il trattamento di strati elettrofo tografici
NL7210017A NL7210017A (sv) 1971-08-02 1972-07-20
DE2236432A DE2236432A1 (de) 1971-08-02 1972-07-25 Verfahren und vorrichtung zur behandlung elektrophotographischer schichten
CH1119372A CH541161A (de) 1971-08-02 1972-07-27 Verfahren zum Regenerieren einer elektrophotographischen Schicht und Vorrichtung zur Ausführung des Verfahrens
GB3531772A GB1397754A (en) 1971-08-02 1972-07-28 Process and apparatus for treating photoconductors
CA148,253A CA982210A (en) 1971-08-02 1972-07-28 Regeneration of photoconductive layer in electrographic process
BE786967A BE786967A (fr) 1971-08-02 1972-07-31 Procede et appareil de regeneration d'une couche photoconductrice
JP47077237A JPS4825534A (sv) 1971-08-02 1972-08-01
FR7227719A FR2149814A5 (sv) 1971-08-02 1972-08-01
SE7209994A SE381522B (sv) 1971-08-02 1972-08-01 Sett och anordning for behandling av elektrofotografiska skikt
US465248A US3910697A (en) 1971-08-02 1974-04-29 Process and apparatus for regenerating a photoconductive layer

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US00168224A US3815295A (en) 1971-08-02 1971-08-02 Process for treating photoconductors

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DE (1) DE2236432A1 (sv)
FR (1) FR2149814A5 (sv)
GB (1) GB1397754A (sv)
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US4076564A (en) * 1974-09-16 1978-02-28 Xerox Corporation Roughened imaging surface for cleaning
US4078924A (en) * 1976-09-13 1978-03-14 Xerox Corporation Imaging surface smoothing with roughened nickel foil
FR2609191A1 (fr) * 1986-12-27 1988-07-01 Canon Kk Appareil electrophotographique
EP0682299A1 (en) * 1994-05-09 1995-11-15 Lexmark International, Inc. Imaging apparatus
US5470271A (en) * 1992-01-02 1995-11-28 Xerox Corporation Flexible belt reclaiming
CN108972160A (zh) * 2018-08-03 2018-12-11 辽宁科技大学 一种复杂轴线弯管内外表面磁粒研磨装置及方法

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JPS5319237U (sv) * 1976-07-28 1978-02-18
JPS54143148A (en) * 1978-04-27 1979-11-08 Canon Inc Zerographic device
JPS55108682A (en) * 1979-02-14 1980-08-21 Toshiba Corp Polishing method of electrophotographic photoreceptor
DE3116421C2 (de) * 1981-04-24 1983-03-31 Siemens AG, 1000 Berlin und 8000 München Anordnung zur Steuerung der Reinigungseinrichtungen in einem nichtmechanischen Druck- oder Kopiergerät
JPS57204064A (en) * 1981-06-11 1982-12-14 Hakko:Kk Reflecting mirror device

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US2484782A (en) * 1948-02-27 1949-10-11 Haloid Co Method of removing electroscopic powder from an electrophotographic plate
US2728103A (en) * 1950-07-22 1955-12-27 Congoleum Nairn Inc Wiper for calender rolls
US3512966A (en) * 1965-07-26 1970-05-19 Ibm Process of electrophotographic recording employing persistent organic photoconductive compositions

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
US2484782A (en) * 1948-02-27 1949-10-11 Haloid Co Method of removing electroscopic powder from an electrophotographic plate
US2728103A (en) * 1950-07-22 1955-12-27 Congoleum Nairn Inc Wiper for calender rolls
US3512966A (en) * 1965-07-26 1970-05-19 Ibm Process of electrophotographic recording employing persistent organic photoconductive compositions

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4076564A (en) * 1974-09-16 1978-02-28 Xerox Corporation Roughened imaging surface for cleaning
US4078924A (en) * 1976-09-13 1978-03-14 Xerox Corporation Imaging surface smoothing with roughened nickel foil
FR2609191A1 (fr) * 1986-12-27 1988-07-01 Canon Kk Appareil electrophotographique
US5470271A (en) * 1992-01-02 1995-11-28 Xerox Corporation Flexible belt reclaiming
EP0682299A1 (en) * 1994-05-09 1995-11-15 Lexmark International, Inc. Imaging apparatus
US5500724A (en) * 1994-05-09 1996-03-19 Lexmark International, Inc. Photoconductor for abrasion in liquid systems
CN108972160A (zh) * 2018-08-03 2018-12-11 辽宁科技大学 一种复杂轴线弯管内外表面磁粒研磨装置及方法

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DE2236432A1 (de) 1973-02-15
NL7210017A (sv) 1973-02-06
BE786967A (fr) 1972-11-16
FR2149814A5 (sv) 1973-03-30
JPS4825534A (sv) 1973-04-03
SE381522B (sv) 1975-12-08
IT962924B (it) 1973-12-31
GB1397754A (en) 1975-06-18
CA982210A (en) 1976-01-20

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