USRE31371E - Developing system - Google Patents

Developing system Download PDF

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Publication number
USRE31371E
USRE31371E US06/297,931 US29793181A USRE31371E US RE31371 E USRE31371 E US RE31371E US 29793181 A US29793181 A US 29793181A US RE31371 E USRE31371 E US RE31371E
Authority
US
United States
Prior art keywords
electrode
developing
latent image
potential
travel
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
US06/297,931
Other languages
English (en)
Inventor
Shoji Kuroishi
Tsuguo Kimura
Masami Emoto
Shiro Yamamoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
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 JP1003373A external-priority patent/JPS5520580B2/ja
Priority claimed from JP5100773A external-priority patent/JPS5432574B2/ja
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
Application granted granted Critical
Publication of USRE31371E publication Critical patent/USRE31371E/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
    • G03G15/065—Arrangements for controlling the potential of the developing electrode

Definitions

  • the invention relates to a developing system for use in a copying process such as an electrophotographic copying process, and more particularly to such a system for developing an electrostatic latent image on a member capable of retaining an electric charge.
  • an electrostatic latent image is formed on a member such as a copying sheet which is capable of retaining an electric charge, and this latent image is subsequently developed.
  • the prior practice has been to charge a photosensitive material, which is subsequently exposed to an image of an article to be copied to have an electrostatic latent image thereof formed thereon.
  • the latent image is then developed and transferred onto a transfer sheet, followed by the fixing thereof.
  • the developing step comprises supplying a developer to the surface of the photosensitive material to develop the electrostatic latent image.
  • a self-bias developing technique has been proposed in which a developer is supplied onto a member on which an electrostatic latent image is formed and which is opposed to an electrically floating, conductive plate (hereinafter referred to as developing electrode).
  • developing electrode is maintained electrically floating so that a potential is induced on the developing electrode by the charge on the image portion of the member in order to attract the toner on the non-image portion of the member to the developing electrode, thereby preventing the background smearing and improving the contrast of the image.
  • the present inventors have previously proposed a developing system for the electrophotographic copying process in which the potential of the developing electrode is induced by the potential of a part of a photosensitive material which is maintained free from image formation and which is maintained at a constant potential when charged during the charging step.
  • the induced potential may happen to be too high and that where a plurality of developing electroes are provided, the potential may vary from electrode to electrode, thus precluding a uniform image characteristic over the entire surface of the photosensitive material.
  • FIG. 1 is a schematic elevation of one exemplary electrophotographic copying apparatus to which the invention can be applied;
  • FIGS. 2 to 7 are schematic sections of several embodiments of the liquid developing system according to the invention.
  • FIG. 8 is an elevation of one exemplary photosensitive material used in the apparatus of FIG. 1;
  • FIGS. 9(a) and 9(b) are perspective views showing examples of the developing electrode shown in FIG. 1.
  • the apparatus comprises a body, having a peripheral surface of photosensitive material 11, in the form of a drum which is driven by a suitable drive means, not shown, for rotation in the direction indicated by an arrow with a constant speed.
  • the body's surface 11 is adapted to be entirely charged by a charger 12, and then exposed to the image of an article to be copied by an exposure unit 13 to form an electrostatic latent image thereon, which latent image is developed with a developing solution in a liquid developing system 14.
  • the electrostatic latent images are formed by a negative high voltage.
  • the polarity of the electrostatic latent image is determined generally in connection with the specific character of the photosensitive material.
  • a transfer sheet 15 is supplied from a paper feeder, not shown, into the space between the drum surface 11 and a transfer unit 16 in synchronism with the movement of the drum surface 11 in order to transfer a toner image from the drum surface 11 onto the transfer sheet 15. While the transfer unit 16 is shown as comprising a transfer roller, it will be understood that it may be replaced by an electrostatic transfer unit. Subsequent to the transfer of the toner image thereto at the transfer unit 16, the transfer sheet 15 has its toner image fixed in a fixing unit, not shown, thereby providing a copy sheet, which is discharged externally of the apparatus. Subsequent to the transfer step, the drum surface 11 is cleaned by a cleaning unit 17.
  • the developing step is effected by the liquid developing system 14.
  • the system 14 comprises a vessel of developing solution 18 located below the drum surface 11, and a counter-electrode 19 disposed within the vessel 18 so as to be opposed to the drum surface 11 with a given space, preferably a spacing between 0.5 to 2 mm.
  • the counter-electrode 19 constitutes an electrically conductive developing electrode, and is formed therein with a liquid inlet 20 and a liquid outlet 21 at positions advanced and retracted with respect to the direction of rotation of the drum surface 11.
  • a developing solution within the vessel 18 is pumped by a pump 22 through the liquid inlet 20 into the space between the drum surface 11 and the counter-electrode 19 for contact with a latent image on the drum surface 11, end is subsequently returned into the vessel 18 through the liquid outlet 21.
  • the counter-electrode 19 is connected to the ground through a constant voltage element, for example, a bidirectional constant voltage element 23, thus allowing a potential to be induced on the electrode by the charge on the drum surface 11. It will be appreciated that the constant voltage element 23 may be a unidirectional constant voltage diode.
  • the potential of the counter-electrode 19 is lower than the potential of the image portion in the latent image on the drum surface 11 and is higher than that of the non-image portion thereof, and is maintained below the threshold value of the constant voltage element 23.
  • the electrostatic latent image on the drum surface 11 is developed by the developing solution supplied, and the toner on the non-image portion is electrically attracted to the counter-electrode 19 to prevent the background smearing and improve the contrast in the image, thus producing the so-called electrode effect.
  • the potential of the counter-electrode 19 varies depending upon the electrostatic latent image on the drum surface 11, so that even with an image of lower density, the background smearing is eliminated and the contrast in the image is improved, and further that the potential of the counter-electrode 19 can not increase beyond the threshold value of the constant voltage element 23, thereby preventing the loss of an image area of reduced density.
  • FIG. 3 Another embodiment of the liquid developing system according to the invention is shown in FIG. 3 wherein the counter-electrode 19 is divided into a plurality of segments 19-1, 19-2 . . . 19-8 which are disposed along the direction of rotation of the drum 11 with a given spacing therebetween and which are carried on an insulating member 24 having a liquid inlet 20' and a liquid outlet 21' formed therein.
  • a constant voltage element 23 is electrically connected between the segment 19-1 and the ground.
  • a plurality of diodes 25-1, 25-2, . . . 25-7 have their anodes connected with the segments 19-1 to 19-7, respectively, and have their cathodes connected with the segments 19-2 to 19-8, respectively.
  • the division of the counter-electrode into a plurality of segments 19-1 to 19-8 reduces the capacitance of the respective segments, thereby improving the leading edge of the induced potential and hence the electrode effect.
  • the segment 19-8 constitutes an auxiliary counter-electrode which is disposed at a position advanced in the direction of travel of the drum with respect to the location where the developing solution is supplied to the image on the drum 11.
  • the segment 19-8 of FIG. 3 is replaced by a roller 26, which serves to remove residual developing solution after the electrostatic latent image on the drum surface 11 has been developed.
  • the developing solution which has been taken off by the roller 26 is scraped by a developing solution removal member 27 to fall into the vessel 18.
  • Both the roller 26 and the member 27 are formed of an insulating material and are held in abutment against each other.
  • the roller 26 is driven by suitable drive means, not shown, to rotate in the direction indicated by an arrow and is charged to the same polarity as the drum surface 11 by friction with the member 27.
  • a conductive finger 28 contacts the roller 26 and is connected with the cathode of the diode 25-7.
  • the segment 19-7 has its potential increased by the charged potential of the roller 26 as transmitted through the finger 28 and the diode 25-7, thereby assuring a satisfactory electrode effect.
  • FIG. 5 shows a modification of the embodiment shown in FIG. 4 in that a constant voltage element contained in the charger serves also as the constant voltage element in the liquid developing system.
  • the charger 12 comprises an electrode 29 which is disposed in opposition to the drum 11 with a grid 30 interposed therebetween and which is mounted within a shielding frame 31.
  • a d.c. source 32 is connected between the electrode 29 and the ground, and the shielding frame 31 is connected to the ground through a chain of constant voltage elements 33 to 36, with the grid 30 connected to the junction between the constant voltage elements 34 and 35.
  • the electrode 29 serves to charge the drum 11 by corona discharge through the grid 30.
  • the junction between the constant voltage elements 35 and 36 is connected with the junction between the diode 25-7 and the finger 28, whereby the potential of the segments 19-1 to 19-7 and the roller 26 is maintained .[.below.]. .Iadd.above .Iaddend.a given value.
  • FIG. 6 there is shown a vessel 37 of developing solution within which a guide member 38 is disposed, and a counter-electrode 39 is disposed above the guide member 38 with a given spacing therebetween.
  • a photosensitive paper 40 having an electrostatic latent image formed thereon is passed between a pair of rollers 41 and 42 and is guided by the guide member 38 to advance through the developing solution within the vessel 37 in order to have its latent image developed. Subsequently the photosensitive paper is delivered to a fixing unit.
  • the counter-electrode 39 is connected to the ground through a constant voltage element 43, and produces the similar electrode effect as mentioned above.
  • the invention can also be applied to an electrophotographic process using a powder developer rather than a developing solution, for example, a cascade developing process. Furthermore, the invention can equally be applied to an electrophotographic process in which the developing takes place by means of a magnetic brush, as shown in FIG. 7.
  • a plurality of magnets 44 to 47 are fixed to an arbor 48 which is driven by suitable means, not shown, for rotation within a hollow cylinder 49.
  • the hollow cylinder 49 is disposed at a position opposite to the drum 11 and is received within a container 50.
  • a developer 51 comprising a mixture of carrier and toner is received within the container 50, and forms a magnetic brush 52 as a result of the attraction acting between the carrier and the magnets 44 to 47.
  • the magnetic brush 52 also rotates around the cylinder 49 to carry the toner toward the surface of the drum 11 for the purpose of developing.
  • a plurality of counter-electrode segments 53-1, 53-2 . . . 53-n are secured on the inner surface of the cylinder 50 and function in the same manner as mentioned previously to provide an electrode effect.
  • the container 50 is provided with a brush length adjusting member 54 and a scraper 55 which scrapes off the magnetic brush 52.
  • the constant voltage element for maintaining the potential of the counter-electrode below a given value may comprise a plurality of such elements connected in series to provide any desired threshold value.
  • FIG. 8 shows a modified body with a surface of photosensitive material 11-2 having an area 11-1 which remains unexposed by the exposure unit 13. Such area may be provided at one end or both ends of the body and may be in the form of a band having a width in the range from 5 to 50 mm, for example.
  • a potential of a given magnitude is induced on the developing electrode 19 by the charged potential on the area 11-1, and is maintained below the threshold value of the constant voltage element 23.
  • the supply of a developing solution to the modified surface 11-2 produces a developing of the electrostatic latent image thereon in the usual manner, and the toner on the non-image portion is electrically attracted by the developing electrode 19 to prevent the background smearing and to improve the contrast in the image, thus producing the electrode effect.
  • the potential of the developing electrode 19 is effectively induced by the potential of the blank area 11-1 to assure a high contrast in the image, and is held below the threshold value of the constant voltage element 23, so that the loss of an image area of reduced density is avoided.
  • Such area 11-1 may comprise an insulating material such as an insulating film or the like.
  • the area 11-1 is kept clear of contact with the transfer sheet, and this may result in overloading the cleaning unit 17.
  • Such an overload can be avoided by providing the developing electrode 19 with a protective member 126 which comprises sponge or felt and is aligned with the area 11-1, as shown in FIG. 9(a), or by providing the developing electrode 19 with a blade 127 comprising an elastomer such as polyurethane rubber, as shown in FIG. 9(b), the member 126 or blade 127 cleaning the area 11-1 of the modified body.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Developing For Electrophotography (AREA)
  • Wet Developing In Electrophotography (AREA)
US06/297,931 1973-01-24 1981-08-31 Developing system Expired - Lifetime USRE31371E (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP1003373A JPS5520580B2 (de) 1973-01-24 1973-01-24
JP48-10033 1973-01-24
JP48-51007 1973-05-07
JP5100773A JPS5432574B2 (de) 1973-05-07 1973-05-07

Related Parent Applications (2)

Application Number Title Priority Date Filing Date
US43527074A Continuation 1973-01-24 1974-01-21
US05/593,293 Reissue US4052127A (en) 1973-01-24 1975-07-07 Developing system

Publications (1)

Publication Number Publication Date
USRE31371E true USRE31371E (en) 1983-09-06

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Family Applications (1)

Application Number Title Priority Date Filing Date
US06/297,931 Expired - Lifetime USRE31371E (en) 1973-01-24 1981-08-31 Developing system

Country Status (3)

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US (1) USRE31371E (de)
DE (1) DE2403186C3 (de)
GB (1) GB1452149A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6308033B1 (en) * 1999-06-02 2001-10-23 Fuji Photo Film Co., Ltd. Image forming method and apparatus using charged particles
US20160259065A1 (en) * 2015-03-02 2016-09-08 Beamocular Ab Ionizing radiation detecting device

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5148341A (de) * 1974-10-24 1976-04-26 Ricoh Kk
DE2550846C2 (de) * 1974-11-12 1983-11-17 Ricoh Co., Ltd., Tokyo Entwicklungseinrichtung für ein elektrophotographisches Kopiergerät
JPS5833551B2 (ja) * 1975-10-01 1983-07-20 株式会社リコー デンシシヤシンフクシヤキニオケル オ−トバイアスゲンゾウホウホウ
JPS5293340A (en) * 1976-02-02 1977-08-05 Ricoh Co Ltd Electronic photographic picture adjustment
DE2715904C3 (de) * 1977-04-09 1981-05-27 Agfa-Gevaert Ag, 5090 Leverkusen Kaskadenentwicklungsvorrichtung für ein elektrostatisches Kopiergerät
GB2041790B (en) * 1979-02-23 1983-07-27 Savin Corp Liquid development of electrostatic images
KR100359109B1 (ko) * 2000-02-25 2002-11-04 삼성전자 주식회사 시트 코팅 장치

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2756676A (en) * 1953-05-04 1956-07-31 Haloid Co Method for the production of electrophotographic prints
US3599605A (en) * 1969-03-20 1971-08-17 Ibm Self-biasing development electrode for electrophotography
US3638610A (en) * 1969-07-03 1972-02-01 Xerox Corp Development apparatus
US3674532A (en) * 1970-07-23 1972-07-04 Eastman Kodak Co Control for bias of magnetic brush and method
US3707943A (en) * 1970-01-09 1973-01-02 Fuji Photo Film Co Ltd Electrophotographic device
US3749059A (en) * 1969-08-27 1973-07-31 Fuji Photo Film Co Ltd Apparatus for developing electrostatic latent image
US3782818A (en) * 1972-11-17 1974-01-01 Savin Business Machines Corp System for reducing background developer deposition in an electrostatic copier
US3818864A (en) * 1971-09-14 1974-06-25 Xerox Corp Image developing apparatus
US3822670A (en) * 1970-12-28 1974-07-09 Fuji Photo Film Co Ltd Liquid development apparatus for electrophotography

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3219014A (en) * 1962-12-04 1965-11-23 Xerox Corp Mechanical shield to protect magnetic core in xerographic developing apparatus
US3249088A (en) * 1963-04-03 1966-05-03 Scm Corp Developing tank unit for electrostatic printing
US3670700A (en) * 1969-07-03 1972-06-20 Xerox Corp Development electrode
GB1360224A (en) * 1970-07-23 1974-07-17 Eastman Kodak Co Bias control of electrographic development electrode
US3719169A (en) * 1971-05-07 1973-03-06 Xerox Corp Plural electrode development apparatus

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2756676A (en) * 1953-05-04 1956-07-31 Haloid Co Method for the production of electrophotographic prints
US3599605A (en) * 1969-03-20 1971-08-17 Ibm Self-biasing development electrode for electrophotography
US3638610A (en) * 1969-07-03 1972-02-01 Xerox Corp Development apparatus
US3749059A (en) * 1969-08-27 1973-07-31 Fuji Photo Film Co Ltd Apparatus for developing electrostatic latent image
US3707943A (en) * 1970-01-09 1973-01-02 Fuji Photo Film Co Ltd Electrophotographic device
US3674532A (en) * 1970-07-23 1972-07-04 Eastman Kodak Co Control for bias of magnetic brush and method
US3822670A (en) * 1970-12-28 1974-07-09 Fuji Photo Film Co Ltd Liquid development apparatus for electrophotography
US3818864A (en) * 1971-09-14 1974-06-25 Xerox Corp Image developing apparatus
US3782818A (en) * 1972-11-17 1974-01-01 Savin Business Machines Corp System for reducing background developer deposition in an electrostatic copier

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6308033B1 (en) * 1999-06-02 2001-10-23 Fuji Photo Film Co., Ltd. Image forming method and apparatus using charged particles
US20160259065A1 (en) * 2015-03-02 2016-09-08 Beamocular Ab Ionizing radiation detecting device
US9880291B2 (en) * 2015-03-02 2018-01-30 Beamocular Ab Ionizing radiation detecting device
US20180231670A1 (en) * 2015-03-02 2018-08-16 Beamocular Ab Ionizing radiation detecting device
US10605929B2 (en) * 2015-03-02 2020-03-31 Beamocular Ab Ionizing radiation detecting device
US11029420B2 (en) 2015-03-02 2021-06-08 Beamocular Ab Ionizing radiation detecting device

Also Published As

Publication number Publication date
DE2403186C3 (de) 1985-11-21
DE2403186B2 (de) 1979-11-29
GB1452149A (en) 1976-10-13
DE2403186A1 (de) 1974-08-01

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