EP0140399B1 - Electrostatic printing and copying - Google Patents

Electrostatic printing and copying Download PDF

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Publication number
EP0140399B1
EP0140399B1 EP84201142A EP84201142A EP0140399B1 EP 0140399 B1 EP0140399 B1 EP 0140399B1 EP 84201142 A EP84201142 A EP 84201142A EP 84201142 A EP84201142 A EP 84201142A EP 0140399 B1 EP0140399 B1 EP 0140399B1
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EP
European Patent Office
Prior art keywords
dielectric
image
pores
impregnant
cylinder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84201142A
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German (de)
English (en)
French (fr)
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EP0140399A1 (en
Inventor
Richard A. Fotland
Leo A. Beaudet
Richard L. Briere
Jeffrey J. Carrish
Donald J. Lennon
Casey S. Vandervalk
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Dennison Manufacturing Co
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Dennison Manufacturing Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/194,649 external-priority patent/US4381327A/en
Priority claimed from US06/222,830 external-priority patent/US4409604A/en
Priority claimed from US06/222,829 external-priority patent/US4365549A/en
Application filed by Dennison Manufacturing Co filed Critical Dennison Manufacturing Co
Priority to AT84201142T priority Critical patent/ATE39392T1/de
Priority to DE8484201142T priority patent/DE3176957D1/de
Publication of EP0140399A1 publication Critical patent/EP0140399A1/en
Application granted granted Critical
Publication of EP0140399B1 publication Critical patent/EP0140399B1/en
Expired legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
    • G03G15/1665—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat
    • G03G15/167—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat at least one of the recording member or the transfer member being rotatable during the transfer
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/18—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a charge pattern
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2092—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using pressure only
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/32—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head
    • G03G15/321—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head by charge transfer onto the recording material in accordance with the image
    • G03G15/323—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head by charge transfer onto the recording material in accordance with the image by modulating charged particles through holes or a slit

Definitions

  • This invention relates to a method of manufacturing an aluminium member for use in electrostatic printing and photocopying, particularly at high speeds.
  • Electrostatic printers and photocopiers share a number of common features as a rule, although they carry out different processes. Electrostatic printers and photocopiers which are capable of producing an image on plain paper may generally be contrasted in terms of the method and apparatus used to create a latent electrostatic image on an intermediate member. Copiers generally do so by uniformly charging a photoconductor electrostatically in the dark, and optically exposing the charged photoconductor to an image corresponding to the image to be reproduced. Electrostatic printers use non-optical means to create a latent electrostatic image on a dielectric surface, in response to a signal indicative of an image to be created.
  • the same apparatus could be used to carry out the common steps of toning the image, transferring it to plain paper, and preparing the member bearing the electrostatic latent image for a subsequent cycle, usually by erasure of a residual latent electrostatic image. It would, in fact, be desirable to standardize the apparatus to perform these functions.
  • toner image transfer methods are known in the art.
  • the transfer may be accomplished electrostatically, by means of a charge of opposite polarity to the charge on the toner particles, the former charge being used to draw the toner particles off the dielectric member and onto the image receptor.
  • Patents illustrative of this transfer method include US-A-2,944,147; US-A-3,023,731; and US-A-3,715,762.
  • the image recetor medium may be passed between the toner-bearing dielectric member and a transfer member, and the toner image transferred by means of pressure at the point of contact.
  • Patents illustrative of this method include US ⁇ A ⁇ 3,701,966; US-A-3,907,560; and US-A-3,937,571.
  • the toner image is fused to the image receptor subsequently to transfer of the image, at a further process station.
  • Postfusing may be accomplished by pressure, as in US-A-3,874,894, or by exposure of the toner particles to heat, as in US-A-3,023,731, and US re-issue patent 28,693.
  • Hardcoat anodization of aluminum and aluminum alloys is an electrolytic process which is used to produce thick oxide coatings with substantial hardness. Such coatings are to be distinguished from natural films of oxide which are normally present on aluminum surfaces and from thin, electrolytically formed barrier coatings.
  • the anodization of aluminum to form thick dielectric coatings takes place in an electrolytic bath containing an oxide, such as sulfuric or oxalic acid, in which aluminum oxide is slightly soluble.
  • an oxide such as sulfuric or oxalic acid
  • Such coatings are extremely hard and mechanically superior to uncoated aluminum.
  • the coatings contain pores in the form of fine tubes with a porosity on the order of 6.4516x 10' 4 to 6.4516 ⁇ 10 16 pores per square meter (10 10 to 10 12 pores per square inch). Typical porosities range from 10 to 30 percent by volume. These pores extend through the coating to a very thin barrier layer of aluminium oxide, typically 3x 10- 8 to 8x10- 8 m (300 to 800 Angstroms).
  • One standard sealing technique involves partially hydrating the oxide through immersion in boiling water, usually containing certain nickel salts, which form an expanded boehmite structure at the mouths of the pores. Oxide sealing in this manner will not support an electrostatic charge due to the ionic conductivity of moisture .trapped in the pores.
  • GB-A-2007157 discloses a method of manufacturing an aluminium member having a dielectric surface layer with a resistivity in excess of 10" ohm-centimetres. This document discloses the features set out in the precharacterising portion of Claim 1.
  • US-A-3664300 discloses a process for surface treatment of xerographic imaging cylinders wherein the surface is coated with zinc stearate to provide enhanced surface lubrication and improved electrostatic toner transfer. This treatment technique does not, however, result in a permanent dielectric surface of requisite hardness and smoothness for pressure transfer and fusing of a toner image.
  • a method of manufacturing an aluminum member having a dielectric surface layer is characterised by the features set out in Claim 1.
  • the invention thus provides a method of manufacturing a dielectric surface layer on an aluminium member which allows compatibility of design for electrostatic printing and photocopying apparatus. It also provides high speed printing and photocopying with excellent image quality.
  • the dielectric surface produced by the method of the invention possesses smoothness and hardness properties which facilitate toner transfer, while possessing sufficient resistivity to obtain a latent electrostatic image until toning.
  • the dielectric surface maintains the above properties at elevated humidities.
  • the technique of the invention may be employed to advantage in producing a dielectric cylinder.
  • the surface is polished to a better than 2.54x10- 8 m (20 microinch) finish.
  • the impregnant material consists essentially of a Group II metal with a fatty acid which may contain, for example, between 8 and 32 carbon atoms, saturated or unsaturated.
  • Figures 1 to 3 show double transfer electrophotographic apparatus 10 comprised of three cylinders, and various process stations.
  • the upper cylinder is a photoconductive member 11, which includes a photoconductor coating 13 supported on a conducting substrate 17, with an intervening semiconducting substrate 15.
  • the photoconductor is electrostatically charged at charging station 19 and then exposed at exposing station 21 to form on the surface of the photoconductor an electrostatic latent image of an original.
  • the photoconductor may be charged employing conventional corona wire assembly, or alternatively it may be charged using the ion generating scheme described in the parent application.
  • the optical image which provides the latent image on the photoconductor may be generated by any of several well known optical scanning schemes.
  • This latent image is transferred to a dielectric cylinder 25 formed by a dielectric layer 27 coated on a metal substrate 29.
  • the latent electrostatic image on the dielectric cylinder 25 is toned and transferred by pressure to a receptor medium 35 which is fed between the dielectric cylinder 25 and a transfer roller 37.
  • the method by which a latent electrostatic image is transferred from the photoconductive cylinder 11 to the dielectric cylinder 25 employs a charge transfer by air gap breakdown.
  • the process of uniformly charging and exposing the surface of the photoconductor coating 13 results in a charge density distribution corresponding to the exposed image, and a variable potential pattern of the surface of the photoconductor coating 13 with respect to the grounded conductive substrate 17.
  • the charged area of the photoconductor 11 is rotated to a position of close proximity (less than 0.05 mm) to the dielectric surface.
  • An external potential 33 is applied between electrodes in the conductive substrate of the photoconductive cylinder 11 and the metal substrate 29 of the dielectric cylinder 25, with a typical initial charge of about 1,000 volts on photoconductive layer 13, to which an additional 400 volts are added by the externally applied potential 33.
  • the aggregate charge of 1,400 volts is decreased by about 800 volts during the exposing process.
  • the charge transfer process requires that a sufficient electrical stress be present in the air gap to cause ionization of the air.
  • the required potential depends on the thickness and dielectric constants of the insulating materials, as well as the width of the air gap (see Dessauer and Clark, Xerography and Related Processes, the Focal Press, London and New York, 1965, at 427). Electrical stress will vary according to the local charge density, but if sufficient to cause an air gap breakdown it will result in a transfer of charge from photoconductor surface 13 to dielectric surface 27, in a pattern duplicating the latent image. This means that a certain threshold potential must be generated across the air gap. Roughly half the charge will be transferred, leaving a potential of around 600 volts on the dielectric surface 27.
  • the necessary threshold potential may exist as a result of the uniform charging and exposure of the photoconductor surface or an externally applied potential may be employed in addition. Image quality is generally enhanced through the use of an external potential.
  • an erase lamp 23 which provides sufficient illumination to discharge the photoconductor below a required level.
  • the erase light 23 may be either fluorescent or incandescent.
  • the cylindrical conducting core 29 of the dielectric cylinder 25 was machined from"7075-T6 aluminum to a diameter of 76 mm.
  • the journals were masked, and the aluminum anodized by use of the Sanford process (see S. Wernick and R. Pinner, The Surface Treatment and Finishing of Aluminum and its Alloys, Robert Draper Ltd., 4th Edition 1971/72, Vol. 2, Page 567).
  • the finished aluminum oxide layer was 60 um (micrometres) in thickness.
  • the cylinder 25 was then placed in a vacuum oven at 101.5917 kPa (30 inches mercury).
  • the oven temperature was set at 150°C.
  • the cylinder was maintained at this temperature and pressure for four hours.
  • the heated cylinder was brush-coated with melted zinc stearate and returned to the vacuum oven for a few minutes at 150°C, 101.59 kPa (30 inches mercury).
  • the cylinder was removed from the oven and allowed to cool.
  • the impregnated surface 27 of the dielectric cylinder 25 was then finished to 0.125 to 0.25 um rms using 600 grit silicon carbide paper.
  • the pressure roller 37 consisted of a solid machined 50 mm diameter core 41 over which was press fitted a 50 mm inner diameter, 62.5 mm outer diameter polysulphone sleeve 39.
  • the conducting substrate 17 of the photoconductor member 11, comprising an aluminum sleeve, was fabricated of 6061 aluminum tubing with a 3 mm wall and a 50 mm outer diameter. The outer surface was machined and the aluminum anodized (again, using the Sanford process) to a thickness of 50 m.
  • nickel sulphide was precipitated in the oxide pores by dipping the anodized sleeve in a solution of nickel acetate (50 g/l, pH of 6) for 3 minutes.
  • the sleeve was then immediately immersed into concentrated sodium sulphide. for 2 minutes and then rinsed in distilled water. This procedure was repeated three times.
  • the impregnated anodic layer was then sealed in water (92° Celcius, pH of 5.6) for ten minutes.
  • the semiconducting substrate 15 was spray coated with a binder layer, the photoconductor coating 13 consisting of photoconductor grade cadmium sulphoselenide powder milled with a heatset DeSoto Chemical Co. acrylic resin, diluted with methyl ethyl ketone to a viscosity suitable for spraying.
  • the dry coating thickness was 40 um, and the cadmium pigment concentration in the resin binder was 18% by volume.
  • the resin was crosslinked by firing at 180°C for three hours.
  • the dielectric cylinder 25 was gear driven from an AC motor to provide a surface speed of twenty cms per second.
  • the pressure roller 37 was mounted on pivoted and spring-loaded side frames, causing it to press against the dielectric cylinder 25 with a pressure of 55 kg per linear cm of contact.
  • the side frames were machined to provide a 1.10 end-to-end between rollers 25 and 37.
  • Strips of tape 0.025 mm thick and 3 mm wide were placed around the circumference of the photoconductor sleeve 11 at each end in order to space the photoconductor at a small interval from the oxide surface of the dielectric cylinder 25.
  • the photoconductor sleeve was freely mounted in bearings and friction driven by the tape which rested on the oxide surface.
  • the photoconductor charging corona station 19, single component latent image toning apparatus 31, and optical exposing station 21 were essentially identical to those employed in the Develop KG Dr. Eisbein & Co. (Stuttgart) No. 444 copier.
  • the toner removal means 43 and 45 comprised flexible stainless steel scraper blades and were employed to maintain cleanliness of both the oxide cylinder 25 and the polysulphone pressure roll 37.
  • the residual latent image was erased using a semiconducting rubber roller in contact with the dielectric surface 27 (see Fig. 5).
  • a DC power supply 33 was employed to bias the photoconductor sleeve 11 to a potential of minus 400 volts relative to the dielectric cylinder core 29, which was maintained at ground potential.
  • the photoconductor surface 13 was charged to a potential of minus 1,000 volts relative to its substrate 17.
  • An optical exposure of 25 lux-seconds was employed in discharging the photoconductor in highlight areas.
  • a latent image of minus 400 volts was transferred to the oxide dielectric 27. This image was toned, and then transferred to a plain paper receptor medium 35 which was injected into the pressure nip at the appropriate time from a sheet feeder.
  • the photoconductor sleeve 11 was replaced with a flexible belt photoconductor 11', as shown in Figure 3.
  • the photoconductor 11' was comprised of a photoconductor layer 13' which was formed from a one to one molar solution of polyvinyl carbazole and trinitrofluorenone dissolved in tetrahydrofuran, and coated onto a conducting paper base 15' (West Virginia Pulp and Paper 45 No. LTB base paper) to a dry thickness of 30 um.
  • the photoconductor rollers 17'a and 17'b were friction driven from the dielectric cylinder 25.
  • the lower roller 17'b was biased to minus 400 volts.
  • the photoconductor was charged to 1,000 volts with the double corona assembly 19' shown in Figure 3.
  • the electrostatic latent image was generated by a flash exposure 21' so that the entire image frame was generated without the use of scanning optics.
  • the rest of the system was identical to the previous example with the exception of the dielectric cylinder 25, which was fabricated from non-magnetic stainless steel coated with a 15 pm layer of high density aluminum oxide.
  • the coating was applied using a Union Carbide Corp. (Linde Division) plasma spray technique. After spraying, the oxide surface was ground and polished to a 0.25 m rms finish. Again, high quality copies were obtained, even at operating speeds as high as 75 cms per second.
  • the electrostatic transfer printing apparatus to be described includes apparatus for forming a latent electrostatic image on a dielectric surface (e.g. an imaging roller) and means for accomplishing subsequent process steps.
  • a dielectric surface e.g. an imaging roller
  • All of the above charging devices are characterised by the production of a "glow discharge", a silent discharge formed in the air between two conductors separated by a solid dielectric.
  • Such discharges have the advantage of being self-quenching, whereby the charging of the solid dielectric to a threshold value will result in an electrical discharge between the solid dielectric and the control electrode.
  • glow discharges are generated to provide a pool of ions of both polarities.
  • control electrode and a “driver electrode”.
  • the control electrode is maintained at a given DC potential in relation to ground, while the driver electrode is energized around this value using a time-varying potential such as a high voltage AC or DC pulse source.
  • Identical apparatus may be employed for both electrophotography and printing to carry out process steps subsequent to the creation on the dielectric cylinder of a latent electrostatic image (compare Figures 1 and 4).
  • the apparatus of Figure 4 will be considered for illustrative purposes.
  • the dielectric layer 75 of the dielectric cylinder 73 should have sufficiently high resistance to support a latent electrostatic image during the period between formation of the latent image and toning, or, in the case of electrophotographic apparatus, between image transfer and toning. Consequently, the resistivity of the layer 75 must be in excess of 10 11 ohm centimeters.
  • the preferred thickness of the insulating layer 75 is between 0.025 and 0.075 mm.
  • the surface of the layer 75 should be highly resistant to abrasion and relatively smooth, with a finish that is preferably better than 0.025 m rms, in order to provide for complete transfer of toner to the receptor sheet 81.
  • the smoothness of dielectric surface 75 contributes to the efficiency of toner transfer to the receptor sheet 81 by enhancing the release properties of this surface.
  • the dielectric layer 75 additionally has a high modulus of elasticity, typically on the order of 6.89476 X 10 7 kPa (10 7 PSI), so that it is not distorted significantly by high pressures in the transfer nip.
  • a number of organic and inorganic dielectric materials are suitable for the layer 75.
  • Glass enamel for example, may be deposited and fused to the surface of a steel or aluminum cylinder. Flame or plasma sprayed high density aluminum oxide may also be employed in place of glass enamel.
  • Plastics materials such as polyamides, polyimides and other tough thermoplastic or thermosetting resins, are also suitable.
  • a preferred dielectric coating is anodized aluminum oxide impregnated with a metal salt of a fatty acid, as described in the parent application.
  • the latent electrostatic image on dielectric surface 75 is transformed to a visible image at toning station 79.
  • any conventional electrostatic toner may be used, the preferred toner is of the single component conducting magnetic type described by JC Wilson, US Patent No. 2,846,333, issued August 5, 1958. This toner has the advantage of simplicity and cleanliness.
  • the toned image is transferred and fused onto a receptive sheet 81 by high pressure applied between rollers 73 and 83. It has been observed that providing a non-parallel orientation, or skew, between the rollers of Figure 4 has a number of advantages in the transfer/fusing process.
  • An image receptor 81 such as plain paper has a tendency to ahere to the compliant surface of the pressure roller 83 in preference to the smooth, hard surface of the dielectric roller 73. Where rollers 73 and 83 are skewed, this tendency has been observed to result in a "slip" between the image receptor 81 and the dielectric surface 75.
  • the most notable advantage is a surprising improvement in the efficiency of toner transfer from dielectric surface 75 to image receptor 81. This efficiency may be expressed in percentage terms as the ratio of the weight of toner transferred to that present on the dielectric roller before transfer.
  • the bottom roller 83 consists of a metallic core 87 which may have an outer covering of engineering plastics 85.
  • the surface material 85 of roller 83 typically has a modulus of elasticity on the order of 1378952 to 3102642 kPa (200,000-450,000 PSI).
  • the image receptor 81 will tend to adhere to the surface 85 in preference to the dielectric layer 75 because of the relatively high smoothness and modulus of elasticity of the latter surface.
  • One function of the plastics coating 85 is to absorb any high stresses introduced into the nip in the case of a paper jam or wrinkle. By absorbing stress in the plastics layer 85, the dielectric coated roller 73 will not be damaged during accidental paper wrinkles or jams.
  • Coating 85 is typically a nylon or polyester sleeve having a wall thickness in the range of 3 to 12.5 mm.
  • the pressure required for good fusing to plain paper is governed by such factors as, for example, roller diameter, the toner employed, and the presence of any coating on the surface of the paper. It has been discovered, in addition, that the skewing of rollers 73 and 83 will decrease the transfer pressure requirements. Typical pressures run from 18 to 125 kg per linear cm of contact.
  • Scraper blades 89 and 91 may be provided in order to remove any residual paper dust, toner accidentally impacted on the roll, and airborne dust and dirt from the dielectric pressure cylinder and the back-up pressure roller. Since substantially all of the toned image is transferred to the receptor sheet 81, the scraper blades are not essential, "but they are desirable in promoting reliable operation over an extended period. The quantity of residual toner is markedly reduced in the embodiment disclosed in the parent application.
  • the small residual electrostatic latent image remaining on the dielectric surface 75 after transfer of the toned image may be neutralized at the latent image discharge station 93.
  • the action of toning and transferring a toned latent image to a plain paper sheet reduces the magnitude of the electrostatic image, typically from several hundred volts to several tens of volts. In some cases where the toning threshold is too low, the presence of a residual latent image will result in ghost images on the copy sheet, which are eliminated by the discharge station 93.
  • any latent electrostatic image can be accomplished by using a high frequency AC potential between electrodes separated by a dielectric.
  • the latent residual electrostatic image may also be erased by contact discharging.
  • the surface of the dielectric must be maintained in intimate contact with a grounded conductor or grounded semiconductor in order effectively to remove any residual charge from the surface of the dielectric layer 75, for example, by a heavily loaded metal scraper blade.
  • the charge may also be removed by a semiconducting roller which is pressed into intimate contact with the dielectric surface.
  • Figure 5 shows a partial sectional view of a semiconductor roller 98 in rolling contact with dielectric surface 75. Roller 98 advantageously has an elastomer outer surface.
  • the cylindrical conducting core 5 of the dielectric cylinder 1 was machined from 7075-T6 aluminium to a 76.2 mm (3 inch) diameter.
  • the journals were masked and the aluminum anodized by use of the Sanford Process (see S. Wernick and R. Pinner, The Surface Treatment and Finishing of Aluminum and its Alloys, Robert Draper Ltd. fourth edition, 1971/72 volume 2, page 567).
  • the finished aluminum oxide layer was 60 microns in thickness.
  • the conducting core was then heated in a vacuum oven, 101.5917 kPa (30 inches mercury), to a temperature of 150°C which temperature was achieved in 40 minutes. The cylinder was maintained at this temperature and pressure for four hours prior to impregnation.
  • a beaker of zinc stearate was preheated to melt the compound.
  • the heated cylinder was removed from the oven and coated with the melted zinc stearate using a paint brush.
  • the cylinder was then placed in the vacuum oven for a few minutes at 150°C, 101.5917 kPa (30 inches mercury), thereby forming dielectric surface layer.
  • the cylinder was removed from the oven and allowed to cool.
  • the member was polished with successively finer SiC abrasive papers and oil. Finally, the member was lapped to a 0.1143 urn (4.5 microinch) finish.
  • the pressure roller 11 consisted of a solid machined two inch diameter aluminum core 12 over which was press fit a 50.8 mm (two inch) inner diameter, 63.5 mm (2.5 inch) outer diameter polysulfone sleeve 13.
  • the dielectric roller was gear driven from an AC motor to provide a surface speed of 304.8 mm/s (12 inches per second).
  • the transfer roller 11 was rotatably mounted in spring-loaded side frames, causing it to press against the dielectric cylinder with a pressure of 5337.4 kg/m (300 pounds per linear inch) of contact.
  • the side frames were machined to provide a skew of 1.1° between rollers 1 and 11.
  • a charging device of the type described in US Patent No. 4,160,257 was manufactured as follows.
  • a 25.4 ⁇ m (1 mil) stainless steel foil was laminated on both sides of a 25.4 um (1 mil) sheet of Muscovite mica.
  • the stainless foil was coated with resist and photoetched with a pattern having holes or apertures in the fingers approximately 0.1524 mm (.006 inch) in diameter.
  • the complete print head consisted of an array of 16 drive lines and 96 control electrodes which formed a total of 1536 crossover locations capable of placing 1536 latent image dots across 195.072 mm (7.68 inch) length of the dielectric cylinder. Corresponding to each crossover location was a 0.1524 mm (.006 inch) diameter etched hole in the screen electrode.
  • Bias potentials of the various electrodes were as follows (with the cylinder's conducting core maintained at ground potential):
  • the DC extraction voltage was supplied by a pulse generator, with a print pulse duration of 10 microseconds. Charging occurred only when there was simultaneously a pulse of negative 400 volts to the fingers 44, and an alternating potential of 2 kilovolts peak to peak at a frequency of 1 Mhz supplied between the fingers 44 and selector bars 43.
  • the print head was maintained at a spacing of 203.2 mm (8 mils) from dielectric cylinder.
  • the printing apparatus 70 included user-actuatable sheet-feeding apparatus (not shown) for feeding individual sheets 81 of paper between cylinders 73 and 83.
  • the paper feed, toning apparatus, and cylinder rotation were driven from a unitary drive assembly (not shown). Paper feed was synchronized with the rotation of dielectric cylinder 73 to ensure proper placement of the toned image.
  • Digital control electronics and a digital matrix character generator designed according to principles well known to those skilled in the art, were employed in order to form dot matrix characters. Each character had a matrix size of 32 by 24 points.
  • a shaft encoder mounted on the shaft of the dielectric cylinder was employed to generate appropriate timing pulses for the digital electronics.
  • This section describes a series of steps for fabricating and treating anodized aluminum members which results in members particularly suited to electrostatic imaging.
  • the treated member is adapted to receive an electrostatic latent image, to carry the image with minimal charge decay to a toning station, and to impart the toned image to a further member preferably by pressure transfer.
  • a number of properties of particular concern in this utilization are the hardness and abrasion resistance of the oxide surface; the potential acceptance and dielectric strength of the dielectric layer; the resistivity of the dielectric layer; and the release properties of the surface with respect to electrostatic toner.
  • This method is advantageously employed in fabricating the dielectric cylinders of the apparatus described above in sections II and III.
  • This method provides a simple and reliable technique for fabricating aluminum oxide layers of a thickness as great as 101.6 um (4 mils) and capable of supporting several thousand volts.
  • Such cylinders are characterized by a hard, smooth surface which is suitably employed in the simultaneous pressure transfer and fusing of a toner image.
  • an initial step entails the fabrication of an aluminum member of desired form.
  • the member consists of a cylinder of aluminum or aluminum alloy, machined to a desired length and outside diameter. The surface is smoothed preparatory to the second step of hardcoat anodization.
  • the machined aluminum member is hardcoat anodized preferably according to the teachings of Wernick and Pinner; see The Surface Treatment and Finishing of Aluminum and its Alloys by S. Wernick and R. Pinner, fourth edition, 1972, published by Rober Draper Ltd., Paddington, England.
  • the anodization is carried out to a desired surface thickness, typically 25.4-50.8 ⁇ m (1-2 mils). This results in a relatively thick porous surface layer of aluminum oxide characterized by the presence of a barrier layer isolating the porous oxide from the conductive substrate.
  • the member's surface is thoroughly rinsed in de-ionized water in order to remove all anodizing bath and other residual substances from the surface and the pores. The rinsed surface may be wiped dry to minimize surface moisture.
  • the method of the invention requires a thorough dehydration of the porous surface layer. For best results, the dehydration is accomplished immediately after anodization. If there is a long delay between these two steps, however, it is advisable to maintain the member in a moisture-free environment in order to avoid a reaction with ambient moisture which leads to the formation of boehmite [AIO(OH) 21 at pore mouths, effectively partially sealing the porous oxide so that subsequent impregnation is incomplete and dielectric properties degraded. This partial sealing can occur at room temperature in normal ambient humidity in a period of several days.
  • Removal of absorbed water from the oxide layer of an anodized aluminum structure may be realized by using either heat, vacuum, or storage of the article in a desiccator.
  • the dehydration step requires thorough removal of water from the pores.
  • heating in a vacuum oven is especially preferred where the member has been stored in a moist environment for a period after anodization. Heating of the member in air, as compared with vacuum heating, results in only a slightly lower level of change acceptance.
  • any thermal treatment of the oxide prior to impregnation be carried out at a temperature in the range from about 80°C to about 300°C, with the preferred temperature being about 150°C.
  • the dehydration step may be accomplished in conjunction with the impregnation step, as explained below.
  • the impregnant material consists essentially of a compound of a Group II or III metal with a long chain fatty acid. It has been discovered that a particularly advantageous class of materials includes the compounds of Group II metals with fatty acids containing between 8 and 32 carbon atoms saturated or unsaturated.
  • the impregnant materials may comprise either a single compound or a mixture of compounds. Due to the water repellant nature of these alkaline earth derivatives, the product of the invention has superior dielectric properties at high humidities.
  • the member In order to avoid introduction of moisture into the dehydrated porous surface layer, the member should be maintained in a substantially moisture-free state during impregnation. This will occur as a natural consequent of the preferred method of applying the impregnant materials of the invention. At room temperature these materials take the form of powders, crystalline solids, or other solid forms. In the preferred embodiment of the invention, the member is maintained at an elevated temperature (above the melting point of the impregnant material) during the impregnation step in order to melt the material or to avoid solidifying premelted material. These materials have sufficiently low viscosity after melting to readily impregnate the pores of the oxide surface layer.
  • the period of heating the member from room temperature to the impregnating temperature may provide the preliminary dehydration which is required to avoid trapped moisture in the pores, often without a prior separate dehydrating step.
  • This preheating stage may take minutes or hours depending on the mass and volume of the aluminum member. See Examples 1, 2.
  • the impregnant material may be applied to the oxide surface under moist ambient conditions because the heating of the aluminum member will tend to drive off any absorbed moisture from the oxide surface.
  • a vacuum may be employed in order to provide an extra precaution against reintroduction of moisture. Special measures may be required, however, in the alternative embodiment in which the impregnant material is dissolved prior to application to the anodized member.
  • the impregnant material is applied to the surface of the aluminum member after heating the member to a temperature above the melting point of the material.
  • the material is applied to the surface in solid form (as by dusting or blowing it onto the surface), whereupon the material will melt.
  • the material is premelted and applied to the oxide surface in liquid form (as by brushing the material onto the member or immersing the member in melted material).
  • the material should then be allowed to spread over the oxide surface layer. This may be done by permitting a flow of the melted material, or by manually spreading the material over the surface using a clean implement.
  • the member should be maintained at this elevated temperature for a period of time sufficient to allow the melted material to completely impregnate the pores of the oxide surface layer. This period will be shorter when using a vacuum to assist impregnation.
  • the material will tend to solidify leaving undesirable air pockets in the pores. It is a particularly advantageous aspect of this method that this problem may be remedied simply by reheating the aluminum member and allowing a more complete filling of the pores.
  • the member may be reheated for a subsequent impregnation step at any time subsequent to the initial impregnation, as the impregnant material of the invention is not permanently cured.
  • the impregnant material is dissolved prior to application of the oxide surface layer.
  • Materials of the invention susceptible to application in this manner include the compounds of Group III metals with fatty acids, as well as the compounds of Group II metals with some of the longer chain fatty acids (those having around 32 carbon atoms). Solvents which are suitable for this purpose include, for example, benzene, and butyl acetate. After the material is dissolved, it may be applied to the member by spraying or brushing it onto the oxide surface layer. The solution is allowed to penetrate the pores. Any excess impregnant is removed by wiping the member's surface.
  • the member may be impregnated in a vacuum oven or in air at a temperature in the range from about 40°C to 55°C.
  • the member may be impregnated in a desiccant dry box.
  • this method would reflect that employed in the prior dehydration step.
  • the member may be reheated as in the preferred embodiment in order to prove a more complete impregnation.
  • the aluminum is allowed to cool.
  • the member is then treated (as by wiping or scraping) to remove any excess material from the surface.
  • a series of panels 38.1 mmx38.1 mmxl.7018 mm (1.5 insx1.5 insx.067 ins) fabricated of aluminium alloy 7075-T6 were hard-coat anodized in sulphuric acid by the Sanford "Plus” process * to a depth of 38.1 pm (1.5 mil). The panels were rinsed with deionized water and wiped free of surface moisture. They were then wrapped in moisture absorbent paper and stored for about one day.
  • the anodized panels were unwrapped and heated to a temperature above the melting point of the material to be applied (see Table I) and maintained at this temperature for one minute prior to application of the impregnant material.
  • the material was dusted onto the heated panel where it melted rapidly and was allowed to flow over the oxide surface layer.
  • the coated member was maintained at the elevated temperature for another minute, and then allowed to cool to room temperature. This process was repeated with a number of different impregnant materials including in one case a mixture of two different compounds-see Table I.
  • the samples were ground with 240 grit sandpaper and water to a thickness of between 40 and 45 microns. They were then heated on a hot plate at 150°C for approximately 30 seconds in order to rapidly evaporate the surface moisture, and then allowed to cool.
  • the plates were placed over a negative ion discharge and charged to a maximum voltage. This voltage was measured by a Monroe Electronics electrostatic voltmeter.
  • a hollow aluminum cylinder of extruded 7075-T651 alloy was machined to an outer diameter of 101.6 mm (4 inches) and 228.6 mm (9 inch) length, with 19.05 mm (0.75 inch) wall thickness.
  • the cylinder was machined to a 7.62x10 -7 m (30 microinch) finish, then polished to a 5.715x10 -8 m (2.25 microinch) finish.
  • the cylinder was hardcoat anodized by the Sanford "Plus" process to a thickness between 42 and 52 microns, then rinsed in deionized water and packed in plastic bags.
  • the cylinder was unpacked and placed in a vacuum oven at 101.5917 kPa (30 inches mercury). After half an hour, the oven temperature was set at 150°C., which temperature was achieved in a further forty minutes. The cylinder was maintained at this temperature and pressure for four hours prior to impregnation.
  • a beaker of zinc stearate was preheated to melt the compound.
  • the heated cylinder was removed from the oven, and coated with the melted zinc stearate using a paint brush.
  • the cylinder was then placed back in the vacuum oven for a few minutes at 150°C, 101.5917 kPa (30 inches mercury). The cylinder was removed from the oven and allowed to cool.
  • the member was polished with successively fine SiC abrasive papers and oil. Finally, the member was lapped to a 11.43 ⁇ 10 -8 m (4.5 microinch) finish by application of a lapping compound and oil with a cloth lap.
  • Example IV-1 Using the testing method of Example IV-1, the cylinder's charge acceptance was measured at 980 volts.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Fixing For Electrophotography (AREA)
  • Printing Methods (AREA)
  • Counters In Electrophotography And Two-Sided Copying (AREA)
EP84201142A 1980-08-21 1981-08-17 Electrostatic printing and copying Expired EP0140399B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AT84201142T ATE39392T1 (de) 1980-08-21 1981-08-17 Elektrostatisches druck- und kopierverfahren.
DE8484201142T DE3176957D1 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
US18021880A 1980-08-21 1980-08-21
US180218 1980-08-21
US06/194,649 US4381327A (en) 1980-10-06 1980-10-06 Mica-foil laminations
US194649 1980-10-06
US06/222,830 US4409604A (en) 1981-01-05 1981-01-05 Electrostatic imaging device
US06/222,829 US4365549A (en) 1978-12-14 1981-01-05 Electrostatic transfer printing
US222829 1981-01-05
US222830 1981-01-05

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
EP81902352.4 Division 1981-08-17

Related Child Applications (4)

Application Number Title Priority Date Filing Date
EP87201989A Division EP0266823A3 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying
EP87201990A Division EP0265994A3 (en) 1980-08-21 1981-08-17 Duplex electrostatic printing and copying
EP87201989.8 Division-Into 1987-10-16
EP87201990.6 Division-Into 1987-10-16

Publications (2)

Publication Number Publication Date
EP0140399A1 EP0140399A1 (en) 1985-05-08
EP0140399B1 true EP0140399B1 (en) 1988-12-21

Family

ID=27497395

Family Applications (5)

Application Number Title Priority Date Filing Date
EP84201142A Expired EP0140399B1 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying
EP85201056A Expired - Lifetime EP0166494B1 (en) 1980-08-21 1981-08-17 Dielectric-electrode laminate
EP87201990A Withdrawn EP0265994A3 (en) 1980-08-21 1981-08-17 Duplex electrostatic printing and copying
EP87201989A Ceased EP0266823A3 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying
EP81902352A Expired EP0058182B1 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying

Family Applications After (4)

Application Number Title Priority Date Filing Date
EP85201056A Expired - Lifetime EP0166494B1 (en) 1980-08-21 1981-08-17 Dielectric-electrode laminate
EP87201990A Withdrawn EP0265994A3 (en) 1980-08-21 1981-08-17 Duplex electrostatic printing and copying
EP87201989A Ceased EP0266823A3 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying
EP81902352A Expired EP0058182B1 (en) 1980-08-21 1981-08-17 Electrostatic printing and copying

Country Status (13)

Country Link
EP (5) EP0140399B1 (enrdf_load_stackoverflow)
JP (1) JPH0415953B2 (enrdf_load_stackoverflow)
AU (3) AU554695B2 (enrdf_load_stackoverflow)
BR (1) BR8108750A (enrdf_load_stackoverflow)
CA (1) CA1170117A (enrdf_load_stackoverflow)
DE (1) DE3177224D1 (enrdf_load_stackoverflow)
ES (1) ES8301037A1 (enrdf_load_stackoverflow)
IL (1) IL63583A0 (enrdf_load_stackoverflow)
IT (1) IT1139412B (enrdf_load_stackoverflow)
MX (2) MX151040A (enrdf_load_stackoverflow)
NZ (1) NZ198031A (enrdf_load_stackoverflow)
PT (1) PT73549B (enrdf_load_stackoverflow)
WO (1) WO1982000723A1 (enrdf_load_stackoverflow)

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GB2156598B (en) * 1984-03-26 1988-03-02 Canon Kk Device and method for charging or discharging
DE3422401A1 (de) * 1984-03-26 1985-09-26 Canon K.K., Tokio/Tokyo Verfahren und vorrichtung zur ladung oder entladung eines bauteils
JPH0630907B2 (ja) * 1985-02-13 1994-04-27 キヤノン株式会社 静電記録方法
GB8922602D0 (en) * 1989-10-06 1989-11-22 British Aerospace A surface discharge plasma cathode electron beam generating assembly
US5017416A (en) * 1989-10-17 1991-05-21 International Paper Company Paper for use in ion deposition printing
US5420662A (en) * 1991-10-15 1995-05-30 Siemens Nixdorf Informationssysteme Aktiengesellschaft Printer or copier with an arrangement for printing both sides of a recording medium
US5601684A (en) * 1992-09-03 1997-02-11 Olympus Optical Co., Ltd. Method for manufacturing an ion flow electrostatic recording head
JPH06175393A (ja) * 1992-12-04 1994-06-24 Fuji Xerox Co Ltd 導電性トナー、その製造法および画像形成法
DE19545113A1 (de) * 1995-12-04 1997-06-05 Heidelberger Druckmasch Ag Digitale Druckmaschine und Verfahren zum Bogentransport dafür
KR100200620B1 (ko) * 1996-09-13 1999-06-15 윤종용 양면인쇄가 가능한 전자사진방식 프린터
US9315021B2 (en) * 2014-02-27 2016-04-19 Xerox Corporation Multiple thin film piezoelectric elements driving single jet ejection system
KR102265168B1 (ko) * 2019-12-30 2021-06-14 백석대학교산학협력단 스트라이프 구조를 이용한 자외선 차단용 자동차 썬팅 필름 및 썬팅 장치

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Also Published As

Publication number Publication date
JPH0415953B2 (enrdf_load_stackoverflow) 1992-03-19
IL63583A0 (en) 1981-11-30
EP0166494B1 (en) 1990-10-17
JPS57501348A (enrdf_load_stackoverflow) 1982-07-29
AU6017186A (en) 1986-12-11
ES504840A0 (es) 1982-12-01
ES8301037A1 (es) 1982-12-01
EP0140399A1 (en) 1985-05-08
PT73549A (en) 1981-09-01
EP0265994A2 (en) 1988-05-04
EP0166494A1 (en) 1986-01-02
AU4092589A (en) 1989-12-07
EP0266823A3 (en) 1988-11-23
NZ198031A (en) 1988-11-29
EP0265994A3 (en) 1988-11-23
PT73549B (en) 1982-11-05
CA1170117A (en) 1984-07-03
AU590297B2 (en) 1989-11-02
MX159260A (es) 1989-05-09
EP0058182A4 (en) 1983-04-06
AU7580481A (en) 1982-03-17
IT8123593A0 (it) 1981-08-21
AU554695B2 (en) 1986-08-28
EP0058182A1 (en) 1982-08-25
MX151040A (es) 1984-09-17
DE3177224D1 (de) 1990-11-22
EP0266823A2 (en) 1988-05-11
EP0058182B1 (en) 1987-03-04
WO1982000723A1 (en) 1982-03-04
BR8108750A (pt) 1982-07-06
IT1139412B (it) 1986-09-24

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