US3715762A - Method and apparatus for generating electrostatic images using ionized fluid stream - Google Patents

Method and apparatus for generating electrostatic images using ionized fluid stream Download PDF

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Publication number
US3715762A
US3715762A US00069647A US3715762DA US3715762A US 3715762 A US3715762 A US 3715762A US 00069647 A US00069647 A US 00069647A US 3715762D A US3715762D A US 3715762DA US 3715762 A US3715762 A US 3715762A
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United States
Prior art keywords
stream
ion
dielectric
ions
selectively
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Expired - Lifetime
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US00069647A
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English (en)
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P Magill
R Mccurry
C Speicher
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International Business Machines Corp
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International Business Machines Corp
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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
    • G03G15/22—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S101/00—Printing
    • Y10S101/37—Printing employing electrostatic force

Definitions

  • An ionized stream is selectively channeled through a printing head to cause image formation on a precharged dielectric coated sheet or to a drain when it is desired to interrupt image formation.
  • the ionized stream in one embodiment, is channeled directly to the dielectric sheet to cause image formation and is-interrupted by a control stream that diverts the ionized stream to the drain.
  • An alternative embodiment provides for a reversal in the functions of the control stream and the ionized stream so that image formation is obtained only when the ionized stream is diverted.
  • Optical methods such as those employed .in xerography and electrofax utilize photoconductive (pc) insulators. These techniques utilize an electrically precharged pc insulating layer coated on a conductive backing (or relatively conductive paper). The charge pattern is generally produced by exposing the uniformly charged pc surface to a pattern of light, i.e.,
  • the charge decay rate is increased as the light intensity is increased.
  • the pc layer contains a charge pattern; the surfaces areas receiving less light are at a larger electrical potential than those areas which have received more light. (The exposure or amount of light being defined as the-product of light intensity and time.)
  • Electrostatic images may also be produced by electrographic methods in which electrical potentials are I applied to styli and/or shaped characters.
  • the applied potential produces an electrical breakdown resulting in electrical charge flow to the dielectric surface layer coated on a conductive base layer.
  • Control of the charge pattern is obtained by switching high voltage (the electrical potential) on and off, either directly by connection of the write electrode to a high voltage pulser or indirectly by, for example, charging conductive pins located in the face of a "cathode ray tube.
  • This fluidic ion method has advantages over electrographic printers in that it obviates high voltage switching and the critical writing head to surface gap control.
  • Another object is to provide a novel printing method in which an electrostatic image is formed by selectively directing a fluid stream of charged ions upon a surface so as to avoid the necessity of switching high voltages as required by the prior art.
  • Yet another object is to provide a novel method of printing which is highly reliable and less costly than prior art non-impact printing schemes.
  • FIG. 1 is a detail of a single writing head used in the formation of an electrostatic image.
  • FIG. 2 is a writing head assembly having a plurality of corona discharge wires housed in a single chamber for forming a plurality of electrostatic images.
  • FIG. 3 is a schematic arrangement of a printing apparatus utilizing the writing heads constituting the present invention.
  • FIG. 4 is a detail drawing of the corona discharge wire. 1
  • a writing head assembly which is essentially an ion generating chamber 1 is comprised of front 1 f, back lb and side walls 1s, lsa covered by a top plate 2 and a grounded base plate 3. Except for the grounded base plate which consists of metal, all walls including the top plate are comprised of an electrical insulating material all held together by suitable means, not shown.
  • the upper plate 2 has a centrally located threaded opening 4 for receiving a corona wire assembly 5 comprised essentially of a long thin wire 5a to which is secured a threaded screw portion 5b that engages with threaded opening 4 by virtue of which the lower end portion 50 of the corona wire can be adjusted relative to a central orifice 6 in the grounded base plate 3.
  • An insulating spacer 7 snugly fitted against the interior wall surfaces of the chamber is positioned to provide rigidity to and maintain the lo cation of the corona wire relative to the center of the orifice 6 in the base plate 3.
  • Pressurized gas for example air
  • a source of high voltage 10 is interconnected in the manner shown by means of lines 11 and 12 to the corona wire and to the grounded base plate.
  • the electrical potential and physical position of the point of the corona wire are adjusted so as to provide a corona discharge.
  • the generated ions emerge from the chamber by way of orifice 6 in the base plate.
  • a lower head portion 13 is secured by means of screws 14a to the grounded base plate 3.
  • This lower head portion is comprised of a configured block 15.
  • a control channel 17 is arranged to intersect the vertical channel 16 through which control channel a gas under pressure is admitted when it is desired to divert the ion stream from the vertical channel 16 to the horizontal control channel 17.
  • the control channel in this instance, discharges into a drain 18 by way of line 18a.
  • the angle of intersection of these two channels 16, 17 may be other than that shown.
  • the ratio of the diameters of these channels l6, 17 may be chosen to provide different conditions of printing.
  • Theparticular embodiment shown enables printing to be accomplished by way of the vertical channel 16'under control of the horizontal control channel 17.
  • the channel 17 is interconnected via a line 17a to a source 17b of pressurized gas.
  • a fluidic control valve 19 Interposed in the line 17a is a fluidic control valve 19 interconnected to and controlled by a suitable valve control means 19b.
  • This means 19b may be any electromechanical structure responsive to control signals related to printing functions. With the valve 19 closed, the ion stream passes unhindered through the vertical channel 16 to impinge and thus cause discharge of a discrete portion of the precharged sheet.
  • Opening of the valve 19 interrupts this action by allowing the pressurized gas in the line 17a to pass through channel 17 and divert the ion stream into the drain 18 by way of line 18a.
  • Beneath the printing head 15, means, not shown, are provided to move the precharged sheet, such as the sheet 20 shown in FIG. 2.
  • the impinging ions exiting from the vertical channel 16 cause a reduction in surface potential of the opposite polarity precharged sheet portions to form an electrostatic image, for example the dotted pattern E, which upon subsequent processing by prior art means produces a visible print of the electrostatic image.
  • the invention by selectively discharging discrete portions of precharged surface by means of a controlled ion stream, provides for the generation of an electrostatic image.
  • the single head arrangement in FIG. 1 can be utilized to print a series of dots or lines, a plurality of these individual heads 1 can be suitably arranged in a single line -(or any other desired arrangement) and held together to provide a multiple recording head assembly to print a plurality of dots, lines or characters.
  • FIG. 2 shows a plurality of corona wires supported in parallel fashion in a single chamber 21 formed of insulating front and back walls 21f, 21b, side walls 21s, 21sa, a top plate 22 and a conducting base plate 23, all held together by suitable means not shown.
  • the corona wire structure is the same as that used in the single head configuration in FIG. 1.
  • These corona wires are positioned in a line and are maintained in position relative to orifices 24 in the base plate 23 by means of the top plate 22 in conjunction with a perforated insulating separator 25 provided with appropriate openings to receive the corona wires.
  • the orifices 24 lead to vertical channels each similar to the channel 16 shown in FIG. 1.
  • these vertical channels are contained in a lower head assembly 26 further containing a plurality of horizontal control channels 27, one of which is shown entering the back wall 21b, each control channel 27 intersecting a vertical channel.
  • Valve means are employed to control the introduction of pressurized gas into the horizontal channels to cause diversion of the ion streams from the vertical channels to and through the horizontal channels.
  • a suitable source of high potential is connected between the corona wires 5' and the base plate 23 which is held at ground potential.
  • Each vertical channel exits at the bottom adjacent to which is located a sheet upon which the exiting ion stream impinges upon the precharged sheet 20 to form an electrostatic image, pressurized gas in this arrangement being admitted by way of line 40.
  • Each vertical channel is controlled by a horizontal channel which is similar to the horizontal channel 17 employed in the head configuration of FIG. 1.
  • the arrangement of FIG. 2 is similar to the multiple head arrangement previously described hereinabove except that the latter uses a single compartment for each corona wire, whereas the arrangement of FIG. 2 utilizes a single compartment to house the plurality of corona wires.
  • Another embodiment of the invention provides for a reversal in the function of the channels 16, 17 to control the formation of the electrostatic image. This is achieved by disconnecting the control lines 27' from the drain and by relocating the precharged sheet 20 to that of 20', partially shown in FIG. 2, adjacent to the output ends 27 of the horizontal control channels from which the diverted ions emerge;.the vertical channel 17 in this instance being connected to a drain.
  • the formation of the electrostatic image by this embodiment is achieved by somewhat diluted ion streams because of the mixture of the control stream with the ion stream.
  • FIG. 3 A printing structure employing the device of a present invention is shown in FIG. 3.
  • This structure employs a rotating grounded conductive cylinder 30 having a dielectric surface coating 31 which is precharged to a uniform surface potential by way of a precharge station 32.
  • the precharged surface then passes under a station 33 comprised of a write heads corresponding to the write heads of the present invention and by means of which desired electrostatic images are formed on the drum surface.
  • the drum surface bearing the images passes under a developer which can be of any type well known in the art.
  • the image bearing surface passes through a transfer station 34 whereat the electrostatic image is transferred to a web of paper 36 issuing from a supply roll 35.
  • the web 36 passes through a fixing station 37 which fixes the transfer image.
  • a drum cleaning station 38 and an erase station 39 are provided to clean the drum surface and discharge the previously formed images in preparation for a new image formation cycle.
  • V is the electrical potential across the dielectric surface layer
  • C is the electrical capacitance per unit area of the dielectric
  • Q is the electrical charge density per unit area
  • the voltage contrast AV produced by fluidic ion deposition of surface charge density Q is directly proportional to AQ, and inversely proportional to the capacitance per unit area.
  • ⁇ N is unipolar ion concentration at the surface per unit volume of fluid
  • q is the charge per ion
  • V is the fluid velocity
  • t is the pulse length or on-time
  • f is the deposition efficiency in percent.
  • the output ion concentration should be i n lo l o +ql -l lo
  • K is the permitivity of free space
  • N is the ion concentration at the entrance
  • a is the ion mobility in an electrical field
  • L is the tube length
  • K is the dielectric constant andd, thickness of the insulator and K, is the permitivity of free space.
  • Typical values of dielectric constants for many dielectric materials are in the range of 2 to 4.
  • MKS meter, kilogram, second
  • a number of methods may be used to generate ions in a moving gas stream, triboelectricity, radiation (at, B, y, X, U, V), corona discharge, microwave breakdown, etc
  • a high speed printer operating in air and near atmospheric pressure one is limited to techniques which will yield high ion concentrations 5 l0 or l0 ions/cm -or higher at the drum or coated paper surface.
  • the most desirable source of corona discharge appears to be that obtained from a discharge point to an orifice at the entrance to the head-set control occurring immediately at the downstream side of the orifice.
  • Typical operating conditions are E 3KV at the point producing 5 6X10 A corona current at the tip and E 10' to 10" A ion current depending on air pressure in the range from 1 to 15 psi above atmospheric pressure through a 0.030 inch inside dia. head.
  • Such currents although low, produce adequate voltage contrast with 2ms pulses so that a toned dot can be obtained with cascade development.
  • the charge involved in this case is E 2X10" coul. distributed on an area of 5 2X10 cm, hence surface charge density is E 10 coul/cm.
  • either uni-polar or bipolar ions may be used. In this instance, however, the
  • resulting electrostatic image may not have the resolution obtainable by utilizing a precharged dielectric surface.
  • the method of forming an electrostatic image on the surface of a dielectric comprising the steps of generating a stream of ions from the pressurized gas, and
  • the method of claim 1 further including the step of precharging the surface of said dielectric prior to directing thereon said stream of ions.
  • the method of claim 1 further including the step of electrically neutralizing the surface of said dielectric prior to directing thereon said stream of ions.
  • Apparatus for generating an ion stream comprising:
  • an ion generating chamber enclosed by electrically non-conducting walls, a top plate and a conducting bottom base plate containing a central opening from which said ion stream emerges,
  • corona discharge wire means supported by said top plate and having an end portion thereof disposed in axial alignment with and in close proximity to said central opening
  • a source of high potential connected across said corona wire and said conducting base plate to cause the generation of said ion stream in the region around said central opening and end portion of said corona wire
  • a lower head assembly secured to said bottom base plate, having a vertical channel communicating with said central opening through which said ion stream emerges, and a horizontal channel intersecting said vertical chanthereby dischar inghsaid portions, said assembly furt er avmg a horizontal channel Intersecting said vertical channel, and
  • Apparatus for forming an electrostatic image on a precharged dielectric surface comprising:
  • an ion generating means for issuing an ion stream
  • a head assembly secured to said ion generating means and having a vertical channel through which said ion stream passes and emerges,
  • said assembly further having a horizontal channel intersecting said vertical channel
  • Apparatus for forming an electrostatic image on a precharged dielectric surface comprising:
  • an ion generator for issuing a plurality of individually controlled ion streams
  • a head assembly secured to said generator and having a plurality of vertical channels through which said ion streams pass and emerge, said assembly further including a plurality of horizontal channels each intersecting a different one of said vertical channels;

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Fax Reproducing Arrangements (AREA)
  • Dot-Matrix Printers And Others (AREA)
US00069647A 1970-09-04 1970-09-04 Method and apparatus for generating electrostatic images using ionized fluid stream Expired - Lifetime US3715762A (en)

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US6964770A 1970-09-04 1970-09-04

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JP (1) JPS5017853B1 (enExample)
BE (1) BE772171A (enExample)
CA (1) CA944009A (enExample)
CH (1) CH527449A (enExample)
DE (1) DE2140563C2 (enExample)
FR (1) FR2107073A5 (enExample)
GB (1) GB1357965A (enExample)
SE (1) SE381755B (enExample)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3815145A (en) * 1972-07-19 1974-06-04 Electroprint Inc Electrostatic printing system and method using a moving shutter area for selective mechanical and electrical control of charged particles
US3834301A (en) * 1971-11-17 1974-09-10 Battelle Memorial Institute Process and device for non-impact printing with liquid ink
US3968499A (en) * 1975-02-19 1976-07-06 Honeywell Inc. Apparatus for producing continuous graphic displays from intermittantly sampled data
US4095233A (en) * 1976-06-30 1978-06-13 Xerox Corporation Method for forming a charge pattern
US4155093A (en) * 1977-08-12 1979-05-15 Dennison Manufacturing Company Method and apparatus for generating charged particles
US4160257A (en) * 1978-07-17 1979-07-03 Dennison Manufacturing Company Three electrode system in the generation of electrostatic images
EP0013709A1 (de) * 1979-01-18 1980-08-06 Robert Bosch Gmbh Verfahren zum Aufzeichnen einer aus einer Vielzahl alphanumerischer Zeichen bestehenden Information
US4338614A (en) * 1979-10-22 1982-07-06 Markem Corporation Electrostatic print head
EP0099243A1 (en) * 1982-07-06 1984-01-25 Xerox Corporation Fluid jet assisted electrographic marking apparatus
EP0120621A1 (en) * 1983-03-02 1984-10-03 Xerox Corporation Electrographic marking apparatus and method
EP0122003A1 (en) * 1983-04-01 1984-10-17 Xerox Corporation Electrographic marking apparatus
US4734721A (en) * 1985-10-04 1988-03-29 Markem Corporation Electrostatic printer utilizing dehumidified air
US4762997A (en) * 1983-11-30 1988-08-09 Xerox Corporation Fluid jet assisted ion projection charging method
US4772901A (en) * 1986-07-29 1988-09-20 Markem Corporation Electrostatic printing utilizing dehumidified air
US4809027A (en) * 1986-07-29 1989-02-28 Markem Corporation Offset electrostatic printing utilizing a heated air flow
US4809026A (en) * 1986-07-29 1989-02-28 Markem Corporation Electrostatic printing utilizing a heated air flow
US5394176A (en) * 1992-03-24 1995-02-28 Nippon Steel Corporation Electrostatic printing apparatus
US6578474B1 (en) * 1998-11-25 2003-06-17 Surfcoat Co., Ltd. Printing or coating method and printing or coating device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH187229A (de) * 1934-03-22 1936-10-31 Ver Gluehlampen & Elec Ag Verfahren und Einrichtung zur Erzeugung von Bildern mittels elektrischer Ladungen.

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3834301A (en) * 1971-11-17 1974-09-10 Battelle Memorial Institute Process and device for non-impact printing with liquid ink
US3815145A (en) * 1972-07-19 1974-06-04 Electroprint Inc Electrostatic printing system and method using a moving shutter area for selective mechanical and electrical control of charged particles
US3968499A (en) * 1975-02-19 1976-07-06 Honeywell Inc. Apparatus for producing continuous graphic displays from intermittantly sampled data
US4095233A (en) * 1976-06-30 1978-06-13 Xerox Corporation Method for forming a charge pattern
US4155093A (en) * 1977-08-12 1979-05-15 Dennison Manufacturing Company Method and apparatus for generating charged particles
US4160257A (en) * 1978-07-17 1979-07-03 Dennison Manufacturing Company Three electrode system in the generation of electrostatic images
EP0013709A1 (de) * 1979-01-18 1980-08-06 Robert Bosch Gmbh Verfahren zum Aufzeichnen einer aus einer Vielzahl alphanumerischer Zeichen bestehenden Information
US4338614A (en) * 1979-10-22 1982-07-06 Markem Corporation Electrostatic print head
EP0099243A1 (en) * 1982-07-06 1984-01-25 Xerox Corporation Fluid jet assisted electrographic marking apparatus
US4463363A (en) * 1982-07-06 1984-07-31 Xerox Corporation Fluid assisted ion projection printing
EP0120621A1 (en) * 1983-03-02 1984-10-03 Xerox Corporation Electrographic marking apparatus and method
EP0122003A1 (en) * 1983-04-01 1984-10-17 Xerox Corporation Electrographic marking apparatus
US4524371A (en) * 1983-04-01 1985-06-18 Xerox Corporation Modulation structure for fluid jet assisted ion projection printing apparatus
US4762997A (en) * 1983-11-30 1988-08-09 Xerox Corporation Fluid jet assisted ion projection charging method
US4734721A (en) * 1985-10-04 1988-03-29 Markem Corporation Electrostatic printer utilizing dehumidified air
US4772901A (en) * 1986-07-29 1988-09-20 Markem Corporation Electrostatic printing utilizing dehumidified air
US4809027A (en) * 1986-07-29 1989-02-28 Markem Corporation Offset electrostatic printing utilizing a heated air flow
US4809026A (en) * 1986-07-29 1989-02-28 Markem Corporation Electrostatic printing utilizing a heated air flow
US5394176A (en) * 1992-03-24 1995-02-28 Nippon Steel Corporation Electrostatic printing apparatus
US6578474B1 (en) * 1998-11-25 2003-06-17 Surfcoat Co., Ltd. Printing or coating method and printing or coating device

Also Published As

Publication number Publication date
DE2140563C2 (de) 1982-02-18
FR2107073A5 (enExample) 1972-05-05
CH527449A (de) 1972-08-31
JPS5017853B1 (enExample) 1975-06-24
GB1357965A (en) 1974-06-26
BE772171A (fr) 1972-01-17
DE2140563A1 (de) 1972-03-09
SE381755B (sv) 1975-12-15
CA944009A (en) 1974-03-19

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