US3792494A - Electrostatic stylus recording with self-cleaning drum - Google Patents

Electrostatic stylus recording with self-cleaning drum Download PDF

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Publication number
US3792494A
US3792494A US00136325A US3792494DA US3792494A US 3792494 A US3792494 A US 3792494A US 00136325 A US00136325 A US 00136325A US 3792494D A US3792494D A US 3792494DA US 3792494 A US3792494 A US 3792494A
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United States
Prior art keywords
electrostatic
recording
recording member
photoconductor
photoconductive layer
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Expired - Lifetime
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US00136325A
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English (en)
Inventor
J Matkan
D Oconnor
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Canon Inc
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Canon Inc
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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
    • G03G5/02—Charge-receiving layers
    • 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
    • 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
    • G03G21/06—Eliminating residual charges from a reusable imaging member

Definitions

  • ABSTRACT A method of electrostatic recording using signal energised styli adjacently disposed across the surface of a photoconductive recording member so that such surface receives atrecording potential to form a latent electrostatic image thereon, then rendering the latent image visible by applying electroscopic marking particles, then transferring the image so formed onto another surface, and cleaning the recording member for further recording by removing residual markingparticles and by removing residual electrostatic charges by lowering the electrical resistivity of the photoconduc-,
  • This invention relates to signal recording and in particular relates to a method whereby the final visual record of such signals may be obtained on any desired surface.
  • Signal recording methods are known in which transmitted information in bit or character form is fed into a receiving station and recorded on a receiving member v in the form of a latent electrostatic image, such image impression being produced by the'application of electrical energy pulses to selected styli, which styli may be in contact with the recording member in those instances where relatively low voltage pulses are used, or alternatively may be placed apart from the recording member in which instances it is usual to use relatively high voltage pulses.
  • the recording member used in conjunction with such prior art means consists of a paper or other conductive backing member having one side thereof a thin continuous layer of insulating material, such as synthetic resin orthe like, which insulating layer is capable of supporting the impressed pattern of electrostatic charge corresponding to the transmitted information for at least suffieient'time to allow development of such latent image.
  • the latent image is subsequently rendered visible by development with a dry or liquid dispersed toner material such as those well known in the art of electrophoqg aphy- Y
  • a dry or liquid dispersed toner material such as those well known in the art of electrophoqg aphy- Y
  • a further form of signal recording apparatus utilises an electrophotographicrecording member such as a Selenium plate or resin bound particulate photoconductor, in which instance the transmitted information is converted to light and selectively transmitted to the electrophotographic recording member by the use of a cathode ray tube flying spot scanner ora fibre optics array or the like, the photoconductor surface having been given a uniform electrostatic charge on its sensitive surface prior to this selective exposure.
  • the thus produced latent image is developed with a dry or liquid dispersed toner material as previously described. In some instances the thus developed image is transferred to a sheet of plain paper or the like, and thus the photoconductor surface is rendered available for further imaging.
  • the prior art processes exhibit certain disadvantages which it is the prime object of this invention to overcome.
  • the image is produced on a specially treated paper, which paper is relatively expensive in comparison with plain paper. It would be advantageous in such equipments to use a permanent recording member and transfer the developed image to a sheet of plain paper, however, it is dif ficult to erase images produced on insulator surfaces to a sufficient extent to allow subsequent re-imaging without also redeveloping the previous image.
  • the second mentioned prior art process can produce copies on plain paper, but the electrophotographic imaging methods are relatively slow in operation and require high intensity light sources severely confined in area to produce images of reasonable definition. In addition cathode ray tubes and fibre optic arrays are each relatively expensive and fragile.
  • electrostatic imaging techniques such as those of the first mentioned prior art processes can be used in conjunction with certain photoconductor recording members in a manner not previously known whereby the high speed and high definition latent image forming capabilities of such stylus impression methods may be used to image a photoconductive recording member, following which the latent image may be developed as previously described and transferred to a sheet of plain paper or the like.
  • the photoconductor properties of the recording member may then be used to remove residual electrostatic patterns on the surface thereof prior to the receipt of further information to be recorded.
  • the recording member in accordance with one embodiment of this instant invention comprises a conductive or relatively conductive base containing on one side thereof a photoconductive layer or coating and said photoconductive layer containing on its surface remote from said conductive base a further layer or coating of a relatively thin insulating material.
  • Such recording member is capable of accepting imagewise electrostatic charges corresponding to signals impressed from styli in presence or in absence of light in view of the aforesaid insulating layer contained over said photoconductive layer.
  • the recording member may have rectifying properties and in case the photoconductor is of the n-type the applied signals can be of positive polarity whereas in case the photoconductor is of the p-type the applied signals can be of negative polarity. In each case imagewise corresponding electrostatic charges having a polarity opposite to the polarity of the charges contained on the surface of the insulating layer will be induced at the interface between the insulating layer and the photoconductive layer.
  • the image-wise charges contained on the surface of the insulating layer can be developed or rendered visible by the application thereto of electroscopic marking particles which can be of the dry or liquid type as commonly known in the art of electrophotography and in common use in office copying machines and the like.
  • the developed image can be transferred to plain paper or other image receiving copy material and such transfer operation can be carried out in the presence of an assisting electrostatic field.
  • Such multiple copies can be obtained in one instance by the successive transfer of partially developed images wherein such partial development allows for redevelopment of residual charges to be carried out and in such instances it is necessary to adjust the transfer conditions and in particular the transfer assisting potential to prevent distortion or destruction of the residual charge.
  • multiple copies can be obtained by the successive transfer of parts only of the developed image and in this case it is also necessary to adjust the transfer conditions and in particular the transfer assisting potential to regulate the quantity of toner transferred in order to obtain more than one transfer copy.
  • the residual charges of the preceding image can be erased by subjecting the recording member to a corona discharge or the like and simultaneously illuminating said recording member surface in order to render the photoconductive layer conductive.
  • the polarity of the corona discharge potential should be opposite to that employed for imaging or at least contain a component of such opposite polarity. Alternating current corona discharge can be used if desired.
  • the recording member in accordance with another embodiment of this invention comprises a conductive or relatively conductive base containing on one side thereof a layer of a photoinsulator upon which the image-wise charges can be impressed as in the first embodiment but in the absence of light.
  • a photoinsulator is a photoconductor with sufficiently high dark resistivity to hold an electric charge on its surface in the dark.
  • the charge images can be developed and transferred, if desired, as described in connection with the first embodiment above, provided such steps for multiple transfer are carried out in the absence of light.
  • the residual charges may be removed by overall exposure to light.
  • the photoconductive layer may consist of a selenium, cadmium sulfide, cadmium selenide, zinc oxide and the like, and may be in powder form incorporated with a film forming resinous binder. Alternatively certain photoconductors may be formed into continuous films by vacuum evaporation, sintering, sublimation and the like. In addition organic photoconductors may be used if desired.
  • the speed of response of the photoconductors may be enhanced by the inclusion of sensitizing agents as is well known in prior art relating to photoconductive films or layers, the sensitising agents being for instance such materials as certain organic dyes or impurity additions within the crystal lattice, such as the metal radicles included as impurities for the purpose of sensitising, or doping as it is commonly referred to, as is well known in relation to cadmium sulfide photoconductive layers.
  • sensitizing agents being for instance such materials as certain organic dyes or impurity additions within the crystal lattice, such as the metal radicles included as impurities for the purpose of sensitising, or doping as it is commonly referred to, as is well known in relation to cadmium sulfide photoconductive layers.
  • the insulating layer of the first embodiment which is maintained in intimate contact with the photoconductive layer is a material of sufficiently high resistivity to support electrostatic charges on its surface and in addition is at least translucent to the light used to erase the residual charge images.
  • Suitable materials are polyester resins, fluorocarbon resins, cellulose acetate, vinyl resins and the like, with surface resistivities generally in excess of lO ohm/sq. centimeter.
  • the thickness of such insulating film is such that it forms a continuous film over the photoconductive layer and no breakdown occurs when the signal charges are applied, and is typically within the range 50 microns, it having been found that films of a thickness of less than 10 microns often contain discontinuities such as pinholes and the like, whereas films greater than 50 microns in thickness may not be completely discharged by the combined action of light and corona due to capacitance effects.
  • FIG. 1 illustrates the first embodiment of this invention in the form of a continuous machine, and it will be realised that certain features are illustrated'by way of example only, and should not be read in the limiting sense;
  • FIG. 2 is a plan of the multiple stylus assembly and switch means
  • FIG. 3 is a view similar to FIG. 1 but showing a modified form.
  • a conductive drum 1 is rotatably mounted on an axle, 2, to rotate in a clockwise direction as shown.
  • a photoconductive layer, 3, is contained on the outer surface of the drum 1, and is in turn overlain with a continuous insulating layer 4.
  • a linear array of writing styli 5, see particularly FIG. 2 are positioned to be in nominal contact with the cylindrical outersurface of insulating layer 4, and each stylus is independently connected to a DC power supply 7, through independent switching means 6, such switching means being controlled by an input signal, the other terminal of the DC power supply 7, being connected to the conducting drum 1, and grounded.
  • the insulating layer 4 is moved in relation tothe various components of the system, and thus each section of the said insulator 4 passes the writing styli 5, at which position an electrostatic latent image corresponding to the input signal is produced on the surface of the insulator 4.
  • the electrostatic latent image is developed on the insulating surface by the attraction of electroscopic powder thereto, which may be brought about by contacting said insulator surface with a roller 9, which roller is partially immersed in a bath 10, containing a suspension of electroscopic marking particles in an insulating carrier liquid 11, such as is well known in the art of electrophotography, and is in common use in electrophotographic office copying machines and the like.
  • apaper web 12 which may be in the form ofa continuous web, or in sheets as desired, contact between the paper web 12, and the developed surface of insulator 4, being maintained by roller 13.
  • roller 13 is connected to a transfer DC power supply 14, whereby an electrostatic field may be applied at the transfer nip to cause the transfer of the developed image from the insulator surface 4, to the paper web 12.
  • the plain paper copy of the information is delivered to outlet tray 15.
  • cleaning means 16 may be in the form of a revolving brush, or a scraper blade, as desired.
  • the insulating surface 4 Before being reimaged the insulating surface 4 passes an electrostatic cleaning means, consisting of an exposure lamp l7 and a corona wire or series of corona points 18, positioned to influence the recording member simultaneously.
  • the corona generating means 18 is connected to a high voltage power supply 19, and the combined influence of corona generating means 18 and light 17 discharges the residual electrostatic charges existing on the insulating surface 4 under the influence of the photoconductor layer 3.
  • FIG. 3 illustrates the second embodiment of this invention, in which the photoconductor layer 103 on the conducting drum 101 is of sufficiently high electrical resistivity to retain the electrostatic latent image withoutthe use of an overlying insulating film.
  • the photoconductor layer 103 will be shielded from light during charging, developing, and transferring of the image. It will be seen that in this embodiment electrostatic cleaning of the photoconductor surface 103 prior to reimaging is carried out by the use of an exposing light only, as the neutralising corona discharge of the first embodiment is not required in the absence of the overlying insulator film of the first embodiment.
  • FIG. 3 also illustrates an alternative developing system, in which the liquid dispersed toner 111 is contained within tank 120, from which it is pumped using the pump 121, to pass through the inlet pipe 122 to pass over the curved plate 123, which plate is in close proximity to the surface of photoconductor layer 103. Unused toner suspension returns to tank 120 through the overflow pipe 124.
  • EXAMPLE 1 This example refers to the first embodiment of this invention.
  • a recording member was prepared by coating a metal drum with a layer of photoconductive cadmium sulfide in a polyester resin binder, the thickness of this layer being 100 microns.
  • a micron polyester film was bonded to the outer surface of said photoconductor layer, to provide a continuous insulating layer thereon.
  • a linear array of writing styli was positioned so that the end of each stylus was in nominal contact with the insulating layer.
  • the styli were 0.007 inch diameter at 0.010 inch centre spacings, and each stylus was connected to a power supply through independent switching means capable of actuation by an input signal.
  • the voltage applied to the styli was of positive polarity, adjustable within the range 0 500- volts.
  • the drum was rotated and a signal used to select and activate individual styli to produce an electrostatic latent image on the insulator surface.
  • the latent image was developed by application of a liquid dispersed toner in which the electroscopic marking particles were of negative polarity in suspension. Such toners are well known.
  • the developed image deposit was transferred to a plain paper web by contacting said paper web with the wet developed image under the influence of a transfer voltage of 100 volts.
  • Residual toner deposit was subsequently removed from the insulating surface using a rotating brush, and residual electrostatic charges were removed from the surface of the recording member prior to reimaging by the combined action of an AC corona potential of 7kV and light.
  • Example 2 The method of Example 1 was repeated using a negative DC corona of 5kV in combination with light to erase residual electrostatic charges on the recording member surface.
  • EXAMPLES 3 and 4 The photoconductor of Examples 1 and 2 was replaced with a 50 micron layer of vitreous selenium, and in these instances the polarity of the writing voltage was reversed, as also was the polarity of the erasing voltage in that instance when DC was used for erasing purposes.
  • EXAMPLES 5 and 6 The photoconductor of Examples 1 and 2 was replaced with a polyvinyl carbazole organic photoconductor.
  • EXAMPLES 7 and 8 The photoconductor of Examples 1 and 2 was replaced with photoconductive zincoxide in an insulating resin binder.
  • EXAMPLE 9 This example refers to the second embodiment of this invention.
  • the photoconductor used was vitreous selenium, which was imaged using a positive polarity ap' plied to the selected styli in the absence of light.
  • the writing voltage used was within the range 5 500 volts.
  • the processing steps were substantially as used in Example l, with the exception that residual electrostatic charges on the recording member surface were removed before reimaging by the application of light only.
  • EXAMPLE 10 The photoconductor of Example 9 was replaced with a layer of photoconductive zinc oxide in an insulating resin binder, and the writing voltage was of negative polarity.
  • the recordingmember of either embodiment can be in the form of a flat plate or a rotatable cylinder or the like over which the signal charges are impressed and the developing, transferring and discharging stations can be arranged conveniently to suit any desired configuration.
  • a signal recording system may be used in which a stylus may contact the surface of the recording member.
  • Individual styli may be within the range of 0.075 mm to 0.2 mm, centre spacing 0.25 mm, and the signal voltage. may be within the range 5V to 1,000V, applied typically for periods within the range 1 microsecond to 5 milliseconds, the higher voltages being used advantageously in conjunction with the smaller diameter styli.
  • a method of electrostatic recording comprising the steps of energizing styli adjacently disposed across the surface of a recording member containing a photoconductive layer by input data signals to selectively charge electrostatically with a recording potential said surface of said recording member to form a latent electrostatic image thereon, rendering visible said electrostatic latent image by applying thereto electroscopic marking particles, transferring such image formed by said marking particles onto another surface, cleaning said surface of said recording member to remove residual marking particles therefrom and removing residual electrostatic charges from said surface of said recording member by lowering the electrical resistivity of said photoconductive layer contained in said recording member by exposure to activating radiation, characterized by a continuous layer of a substantially transparent insulating material forming said surface of said recording member wherein said insulating layer is contained over said photoconductive layer and wherein the electrical resistivity of such insulating material is sufficiently high to permit said surface to retain said electrostatic image formed thereon, further characterised in that the residual electrostatic charges are removed from said surface of said recording member by the combined action of exposure of said photoconductive layer to activ
  • a method of electrostatic recording according to claim 1 characterised in that the photoconductor of said photoconductive layer is cadmium sulfide and has over it a continuous layer ofa substantially transparent insulating material forming said surface of said recording member, the electrical resistivity of such insulating material being sufficiently high to permit said surface to retain said electrostatic latent image formed thereon.
  • a method of electrostatic recording according to claim 1 characterised in that the photoconductor of said photoconductive layer is cadmium sulfide and has over it a continous layer of polyester resin which forms the surface of said recording member, and has an electrical resistivity sufficiently high to permit said surface to retain said electrostatic latent image formed thereon.
  • a method of electrostatic recording according to claim 1 wherein the insulator applied over the photoconductor has a resistivity in excess of lO ohmlsquare centimeter and a thickness of 10 to 50 microns and is taken from the group: polyester resins, fluorocarbon resins, cellulose acetate, and vinyl resins.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
  • Fax Reproducing Arrangements (AREA)
  • Photoreceptors In Electrophotography (AREA)
US00136325A 1970-05-01 1971-04-22 Electrostatic stylus recording with self-cleaning drum Expired - Lifetime US3792494A (en)

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AU107570 1970-05-01

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US (1) US3792494A (enrdf_load_stackoverflow)
JP (1) JPS5433134B1 (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5404972A (en) * 1993-04-30 1995-04-11 Fichtel & Sachs Industries, Inc. Self-blocking gas spring with temperature-responsive bypass valve
US5631727A (en) * 1991-04-30 1997-05-20 Canon Kabushiki Kaisha Image forming apparatus having discharging means using light source actuated prior to latent image formation
US5911175A (en) * 1996-02-24 1999-06-15 Man Roland Druckmaschinen Ag Method and device for cleaning a printing machine cylinder surface
US6473107B2 (en) * 2000-10-02 2002-10-29 Seiko Epson Corporation Image forming apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3343142A (en) * 1963-01-02 1967-09-19 Xerox Corp Xerographic coding and information storage on a specular business machine card
US3355289A (en) * 1962-05-02 1967-11-28 Xerox Corp Cyclical xerographic process utilizing a selenium-tellurium xerographic plate
US3536483A (en) * 1964-10-20 1970-10-27 Katsuragawa Denki Kk Method of making electrographs wherein the resultant electrostatic image is not effected by further light exposure

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3154414A (en) * 1960-04-18 1964-10-27 Minnesota Mining & Mfg Image removal
JPS448870Y1 (enrdf_load_stackoverflow) * 1966-03-15 1969-04-10

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3355289A (en) * 1962-05-02 1967-11-28 Xerox Corp Cyclical xerographic process utilizing a selenium-tellurium xerographic plate
US3343142A (en) * 1963-01-02 1967-09-19 Xerox Corp Xerographic coding and information storage on a specular business machine card
US3536483A (en) * 1964-10-20 1970-10-27 Katsuragawa Denki Kk Method of making electrographs wherein the resultant electrostatic image is not effected by further light exposure

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5631727A (en) * 1991-04-30 1997-05-20 Canon Kabushiki Kaisha Image forming apparatus having discharging means using light source actuated prior to latent image formation
US5404972A (en) * 1993-04-30 1995-04-11 Fichtel & Sachs Industries, Inc. Self-blocking gas spring with temperature-responsive bypass valve
US5911175A (en) * 1996-02-24 1999-06-15 Man Roland Druckmaschinen Ag Method and device for cleaning a printing machine cylinder surface
US6473107B2 (en) * 2000-10-02 2002-10-29 Seiko Epson Corporation Image forming apparatus

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JPS5433134B1 (enrdf_load_stackoverflow) 1979-10-18

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