US3927409A - Multistage thin film toning system for developing charged images - Google Patents

Multistage thin film toning system for developing charged images Download PDF

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Publication number
US3927409A
US3927409A US249258A US24925872A US3927409A US 3927409 A US3927409 A US 3927409A US 249258 A US249258 A US 249258A US 24925872 A US24925872 A US 24925872A US 3927409 A US3927409 A US 3927409A
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US
United States
Prior art keywords
toner
recording medium
squeegee
toning
applying means
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 - Lifetime
Application number
US249258A
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English (en)
Inventor
Heino Kase
Edward W Marshall
Survrat Kirtikar
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Varian Medical Systems Inc
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Varian Associates Inc
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
Application filed by Varian Associates Inc filed Critical Varian Associates Inc
Priority to US249258A priority Critical patent/US3927409A/en
Priority to FR7314942A priority patent/FR2183017B1/fr
Priority to DE2321192A priority patent/DE2321192A1/de
Priority to GB2023173A priority patent/GB1425404A/en
Priority to CA169,833A priority patent/CA981014A/en
Priority to JP48048982A priority patent/JPS4949637A/ja
Application granted granted Critical
Publication of US3927409A publication Critical patent/US3927409A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • 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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/11—Removing excess liquid developer, e.g. by heat

Definitions

  • This invention relates to multistage toning and more particularly to thin film liquid toning.
  • the toning process is initiated by exposing the charge image to charged toner particles dispersed as a colloid in an insulating liquid diluent or carrier liquid.
  • Mutual electrostatic attraction causes the toner particles to deposit on the charge image. This attraction force is directly proportional to the square of the distance between the charge image and the charge toner particle.
  • the toner particles deposited on the charge image adhere thereto to form a permanentvisible image.
  • the toner density of the final image and development time required are a function of the charge intensity on the paper, the magnitude of the charge on the toner particles, the viscosity and temperature of the diluent, and the concentration of toner particles in the diluent.
  • the toning process is initially vigorous and gradually decays because the net charge on the paper decreases due to the neutralizing effect of the deposited charged toner particles.
  • the force of attraction between the toner particles and the paper is correspondingly reduced.
  • a further decrease in the toning activity is caused by depletion of the toner in the boundary layer formed immediately adjacent to the paper.
  • the toner particles more remote from the paper are attracted with less force and have a greater distance to travel.
  • FIG. 1 shows an exponential curve of toning completed plotted against time representing the above mathematical relationship. The first derivative of this curve the rate of toner activity or toner particle transfer is initially very great, and progressively decreases approaching zero as the toning approaches 100%. Under the toning conditions of the preferred embodiment, 3% seconds are required to form an 80% toned image.
  • the decrease in toner rate is caused by a gradual decrease in electrostatic forces of attraction due to the neutralization of the charge image, and to gradual depletion of the toner in the thin film or boundary layer proximate the moving web. This laminar flow caused by relative motion between the paper and the toner, prevents fresh toner from approaching the paper.
  • FIG. 1 is a curve of percent toning versus exposure time of a single stage prior art toning system showing the effects of toner depletion and laminar flow;
  • FIG. 2 is a schematic view of the present multistage toning apparatus
  • FIG. 3 is a pictorial view of the toning station of FIG. 1 broken away to show the flow equalizing structure therein;
  • FIG. 4 is a curve of percent toning versus time of a two stage toning device of FIG. 2 showing the increase of toning rate brought about by squeegeeing of the boundary layer and applying fresh toner.
  • FIG. 2 shows an electrostatic recorder 10 which forms a charge image on web 12 by electrical interaction between a recording head 14 containing styli l6 and a backplate l8 spaced therefrom to permit passage of the web 12.
  • Drive roller 20 moves web 12 with the charge image formed thereon along a path of motion past a toning station 22 which includes a first toning slot 24, a squeegee bar 26 and a second toning slot 28.
  • a toning pump 30 pumps toner from toner supply 32 through toner filter 34 and into a station reservoir 36 in toning station 22.
  • the incoming toner passes through a flow equalizing perforated baffle 38 described in more detail in FIG. 3.
  • the toner moves upward in planar columns 40 and 42 and onto web 12 through first toning slot 24 and second toning slot 28 respectively,
  • the toner is supplied to the moving web 12 in a thin film 41 which initially develops the charge image very actively.
  • the toning activity decreases as thin film 41 approaches toner depletion.
  • Depleted toner film 41 is removed from web 12 by squeegee bar 26.
  • Fresh toner is applied to the squeegeed partially toned charge image by second toning slot 28 forming thin toner film 43.
  • This second toner film 43 is removed from web 12 by the pressing action of a squeegee roller 44 mounted proximate drive roller 20.
  • the twice toned paper web 12 is then directed out of recorder 10 for visible inspection (not shown). Toning is permitted in each stage only during the initial period when the toning rate is high. After the charge image exposed to each toning stage reaches about 50% toned, the toning rate has slowed down greatly and continued toning is inefficient. After about 50% toning in any stage, the toner film should be squeegeed off and fresh toner applied.
  • Toner film 41 removed from web 12 by squeegee bar 26 flows down squeegee bar 26 into a toner collection trough 46.
  • Toner film 43 removed from web 12 by squeegee roller 44 flows downward into a toner pan 48 which also collects toner from collection trough 46.
  • the toner in pan 48 drains through a toner return line 3 50 back to toner supply 32.
  • a guide roller 52 is provided to contour web 12 around the curved surface of writing head 14 and to seal web 12 against a lip 54 which forms the leading edge of first toning slot 24.
  • the sealing between web 12 and lip 54 prevents toner from flowing down the outside of toning station 22, and establishes the toner flow parallel to and in the same direction as web 12 motion to promote the formation of thin film 41.
  • Thin film 41 is limited to less than mils in thickness due to the viscosity and surface tension of the toner, and is equivalent to a 5 mil drag free boundary layer moving along with the web.
  • the boundary layers of the prior art were much thinner due to fluid drag between the moving boundary layer and the remaining stationary toner.
  • the differential velocities thus established between the web and the toner inhibited toner particle migration to the web.
  • the present drag free boundary layer moves in unison with the web and the differential velocity problem is avoided.
  • the only limitation on drag free boundary layers 41 and 43 is toner depletion which occurs in a much thinner thickness than 5 mils
  • FIG. 3 shows in greater detail the internal structure of station reservoir 36 which establishes a uniform toner flow along the length of toning slots 24 and 28.
  • the toner enters reservoir 36 at entrance ports 60 into a lower reservoir chamber 62.
  • Perforated baffle 38 separates lower chamber 62 from an upper chamber 64 and uniformly distributes the incoming toner flow along the entire length of toning station 22.
  • Upper reservoir chamber 64 forms planar toner columns 40 and 42 which flow out toning slots 24 and 28.
  • the uniform flow is established by breaking up the flow pattern issuing from ports 60.
  • the flow pattern is disrupted by the multiple changes in direction caused by baffle 38 and the space apertures therein.
  • Prior art toner spraying devices did not uniformly spray the toner which caused light and dark areas in the resulting toned image. These prior art devices are analogous to lawn sprinklers it is difficult to obtain uniform watering.
  • web 12 is moved at a rate of 1.67 inches per second.
  • First toning slot 24 is spaced about 0.9 inches from squeegee bar 26 and second toning slot 28 is spaced about 1.6 inches from the contact point between squeegee roller 44 and drive roller 20.
  • the toning stations have a toning exposure time of about 0.54 and 0.96 seconds respectively.
  • FIG. 4 shows a curve of percent toning versus time of a two stage toning station. At time zero web 12 is initially toned at toning slot 24. At .54 the partially depleted toner is removed from web 12 by squeegee bar 26. At this point web 12 is about 35% toned.
  • Fresh toner is immediately applied to web 12 through second toning slot 28.
  • the toning is 80% complete.
  • the total time elapsed for 80% toning by the present multistage toning system is only 1.50 seconds.
  • FIG. 1 shows 3.25 seconds required to accomplish 80% toning with a single stage toner of the prior art.
  • the toning slots are about 60 mils wide and about 14.25 inches long.
  • the uniform flow rate is established by 7 apertures 0.125 inches in diameter provided on baffle 38 spaced about 2 inches apart.
  • the preferred toner flow rate is about 90 cubic inches per minute.
  • a 3 mil toner film on a l4 inch web traveling l.67 inches per second requires 7 cubic inches of toner per minute, and it is essential that pump 30 supply at least this flow quantity to maintain a uniform film.
  • the toning rate of thin films 41 and 43 are independent of the toner flow rate because the thickness of films 41 and 43 are determined by the viscosity and surface tension of the toner. Variations in toner flow may change the amount of excess toner which flows down the outside walls of toning station 22; but flow variations will not affect the thickness of toner films 41 and 43 so long as a critical minimum flow rate is maintained.
  • a recording device for forming a charge image on the charge retentive surface of a recording medium and toning the charge image with toner particles dispersed in a carrier liquid, comprising the combination:
  • each of said toner applying means arranged to apply a thin film of toner to the charge image on the recording medium;
  • liquid toner squeegee means positioned between each of the spaced toner applying means to remove the thin film of toner from the charge retentive surface before the toner becomes substantially depleted of toner particles;
  • final liquid toner squeegee means positioned subsequent to the last toner applying means along the path of motion to remove the thin film of toner applied by the last toner applying means.
  • the plurality of toner applying means are formed by a slot opening at the top of an upwardly directed channel extending across the recording medium generally transverse of the direction of web motion, the leading edge of the slot opening extending slightly higher than the trailing edge of the slot opening to form a bar type squeegee which removes the thin film of toner from the recording medium immediately prior to applying toner thereto from the slot opening.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Wet Developing In Electrophotography (AREA)
US249258A 1972-05-01 1972-05-01 Multistage thin film toning system for developing charged images Expired - Lifetime US3927409A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US249258A US3927409A (en) 1972-05-01 1972-05-01 Multistage thin film toning system for developing charged images
FR7314942A FR2183017B1 (OSRAM) 1972-05-01 1973-04-25
DE2321192A DE2321192A1 (de) 1972-05-01 1973-04-26 Aufzeichnungsgeraet
GB2023173A GB1425404A (en) 1972-05-01 1973-04-27 Liquid development of electrostatic charge images
CA169,833A CA981014A (en) 1972-05-01 1973-04-30 Multistate thin film toning system for developing charged images
JP48048982A JPS4949637A (OSRAM) 1972-05-01 1973-05-01

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US249258A US3927409A (en) 1972-05-01 1972-05-01 Multistage thin film toning system for developing charged images

Publications (1)

Publication Number Publication Date
US3927409A true US3927409A (en) 1975-12-16

Family

ID=22942682

Family Applications (1)

Application Number Title Priority Date Filing Date
US249258A Expired - Lifetime US3927409A (en) 1972-05-01 1972-05-01 Multistage thin film toning system for developing charged images

Country Status (6)

Country Link
US (1) US3927409A (OSRAM)
JP (1) JPS4949637A (OSRAM)
CA (1) CA981014A (OSRAM)
DE (1) DE2321192A1 (OSRAM)
FR (1) FR2183017B1 (OSRAM)
GB (1) GB1425404A (OSRAM)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3991709A (en) * 1971-02-09 1976-11-16 Canon Kabushiki Kaisha Regenerating device for developing liquid
US4151314A (en) * 1973-05-01 1979-04-24 The Broken Hill Proprietary Company, Limited Method of lining container closures
US4300476A (en) * 1979-05-25 1981-11-17 Herbert Kannegiesser Gmbh & Co. Apparatus for the stiffening of textile sheets by coating with plastic
US5109794A (en) * 1990-09-27 1992-05-05 Nippon Steel Corporation Pump device for electrostatic plotter
US5236505A (en) * 1991-07-29 1993-08-17 Nylok Fastener Corporation Apparatus and method for applying liquid material to a fastener
EP0510180A4 (en) * 1990-11-14 1993-12-15 Colorep, Inc. Multicolor development system having detachable liquid cartridges
US5649271A (en) * 1996-06-27 1997-07-15 Xerox Corporation Air handling system for a development housing
US5701561A (en) * 1995-09-26 1997-12-23 Minnesota Mining And Manufacturing Company Method and apparatus for applying liquid toner to a print medium using multiple toner applicators for each liquid toner
WO1999036187A1 (en) * 1998-01-19 1999-07-22 First Light Technology, Inc. Process and device for coating disks

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2956494A (en) * 1956-01-13 1960-10-18 Kelvin & Hughes Ltd Application of liquid to surfaces
US3094914A (en) * 1959-04-06 1963-06-25 Cons Electrodynamics Corp Photographic development equipment
US3196832A (en) * 1963-02-20 1965-07-27 Rca Corp Fluid applicator apparatus
US3344729A (en) * 1964-06-22 1967-10-03 Itek Corp Photographic sheet material processing apparatus
US3345927A (en) * 1964-06-26 1967-10-10 Gen Aniline & Film Corp Apparatus for rapid development of photographic film
US3371651A (en) * 1966-11-10 1968-03-05 Rca Corp Fluid applicator apparatus
US3470848A (en) * 1965-10-24 1969-10-07 Donald F Dreher Web coating apparatus
US3474757A (en) * 1965-10-24 1969-10-28 Donald F Dreher Multiple coating apparatus
US3664298A (en) * 1970-03-26 1972-05-23 Rca Corp Manifold for fountain-type liquid dispenser
US3690297A (en) * 1969-07-22 1972-09-12 Blandin Paper Co Non-aqueous coating of webs
US3788844A (en) * 1971-10-05 1974-01-29 Fuji Photo Film Co Ltd Charging method for electrophotography

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2956494A (en) * 1956-01-13 1960-10-18 Kelvin & Hughes Ltd Application of liquid to surfaces
US3094914A (en) * 1959-04-06 1963-06-25 Cons Electrodynamics Corp Photographic development equipment
US3196832A (en) * 1963-02-20 1965-07-27 Rca Corp Fluid applicator apparatus
US3344729A (en) * 1964-06-22 1967-10-03 Itek Corp Photographic sheet material processing apparatus
US3345927A (en) * 1964-06-26 1967-10-10 Gen Aniline & Film Corp Apparatus for rapid development of photographic film
US3470848A (en) * 1965-10-24 1969-10-07 Donald F Dreher Web coating apparatus
US3474757A (en) * 1965-10-24 1969-10-28 Donald F Dreher Multiple coating apparatus
US3371651A (en) * 1966-11-10 1968-03-05 Rca Corp Fluid applicator apparatus
US3690297A (en) * 1969-07-22 1972-09-12 Blandin Paper Co Non-aqueous coating of webs
US3664298A (en) * 1970-03-26 1972-05-23 Rca Corp Manifold for fountain-type liquid dispenser
US3788844A (en) * 1971-10-05 1974-01-29 Fuji Photo Film Co Ltd Charging method for electrophotography

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3991709A (en) * 1971-02-09 1976-11-16 Canon Kabushiki Kaisha Regenerating device for developing liquid
US4151314A (en) * 1973-05-01 1979-04-24 The Broken Hill Proprietary Company, Limited Method of lining container closures
US4300476A (en) * 1979-05-25 1981-11-17 Herbert Kannegiesser Gmbh & Co. Apparatus for the stiffening of textile sheets by coating with plastic
US5109794A (en) * 1990-09-27 1992-05-05 Nippon Steel Corporation Pump device for electrostatic plotter
EP0510180A4 (en) * 1990-11-14 1993-12-15 Colorep, Inc. Multicolor development system having detachable liquid cartridges
US5236505A (en) * 1991-07-29 1993-08-17 Nylok Fastener Corporation Apparatus and method for applying liquid material to a fastener
US5701561A (en) * 1995-09-26 1997-12-23 Minnesota Mining And Manufacturing Company Method and apparatus for applying liquid toner to a print medium using multiple toner applicators for each liquid toner
US5649271A (en) * 1996-06-27 1997-07-15 Xerox Corporation Air handling system for a development housing
WO1999036187A1 (en) * 1998-01-19 1999-07-22 First Light Technology, Inc. Process and device for coating disks

Also Published As

Publication number Publication date
FR2183017A1 (OSRAM) 1973-12-14
FR2183017B1 (OSRAM) 1979-01-12
CA981014A (en) 1976-01-06
GB1425404A (en) 1976-02-18
DE2321192A1 (de) 1973-11-22
JPS4949637A (OSRAM) 1974-05-14

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