US3817748A - Contrast control in electrostatic copying utilizing liquid development - Google Patents

Contrast control in electrostatic copying utilizing liquid development Download PDF

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Publication number
US3817748A
US3817748A US00221669A US22166972A US3817748A US 3817748 A US3817748 A US 3817748A US 00221669 A US00221669 A US 00221669A US 22166972 A US22166972 A US 22166972A US 3817748 A US3817748 A US 3817748A
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United States
Prior art keywords
image
areas
area
contrast
halftone
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Expired - Lifetime
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US00221669A
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English (en)
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G Whittaker
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Xerox Corp
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Xerox Corp
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Priority to US00221669A priority Critical patent/US3817748A/en
Priority to CA155,146A priority patent/CA991246A/en
Priority to NL7300584A priority patent/NL7300584A/xx
Priority to GB379073A priority patent/GB1406794A/en
Priority to JP48011802A priority patent/JPS4885142A/ja
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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
    • G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material
    • G03G15/102—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material for differentially wetting the recording material
    • 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

Definitions

  • This invention relates to electrostatic copying.
  • the invention relates more particularly to improvements in electrostatic copying employing liquid development techniques.
  • a latent image is established electrostatically on an image retention surface and is developed by contacting the surface with a liquid developing material.
  • the development material ad heres to the surface and conforms to the image.
  • the image is then transferred to a record medium for recording.
  • polar liquid development In one image development process sometimes termed polar liquid development, the liquid developer or ink is delivered to the image retention surface by a dispensing member. The ink transfers from the dispensing member in image configuration to the retention surface by virtue of electrostatic forces established by charged areas on the image retention surface.
  • This polar liquid development process is described in detail in U.S. Pat. 3,084,043 which is assigned to the assignee of this invention.
  • a halftone printing format utilizes information elements such as dots or the like. Contrast between different subjects in an image is established in halftone format by the difference in density or relative size of dots in one area with respect to those in another.
  • the density, D, of a halftone image can be expressed as:
  • Another object of this invention is to provide an improved electrostatic copying process employing liquid development.
  • Another object of the invention is to provide contrast control in an electrostatic copying process employing liquid development.
  • Another object of the invention is to provide an electrostatic copying process for halftone originals wherein a halftone informational element is varied in size.
  • a further object of the invention is to provide a process for the production of a halftone copy from a continuous tone original.
  • the contrast density between a halftone original and a halftone image is approximately equal to the ratio between the dot area in the image to the dot area in the halftone original.
  • contrast control in an electrostatic copying process employing polar liquid development is effected by controlling the exposure of an image retention surface in order to establish charged information areas having a total area A',, which has a proportional relationship R, to surrounding buffer areas A'
  • This ratio R differs from a proportional relationship R existing between information element areas A and butfer area A of the object.
  • an electrostatic copying process for increasing contrast comprises the steps of forming a uniform electrostatic charge on an image retention surface; altering the charge on the image retention surface in order to provide a large plurality of highly charged information elemental areas Ag, surrounded by buffer areas A' bearing a relatively high residual charge to which ink will be laterally drawn and arranged in an image configuration corresponding to a halftone original; delivering a developing liquid to the retention surface for developing said image; and transferring the developed liquid image to a record medium.
  • FIG. 1 is a schematic view of an electrostatic copying apparatus employing liquid development and operating in accordance with the method of this invention
  • FIG. 2 is a side view of a liquid developing material transfer member of FIG. 1;
  • FIG. 3 is a sectional view of an image retention surface and liquid developing material transfer member illustrating transfer of a liquid developing material to the image retention surface;
  • FIG. 4 is a diagram illustrating the lateral flow of liquid developing material and the associated surface charge on an image retention surface for one value of residual charge retention;
  • FIG. 5 is a diagram illustrating the lateral flow of liquid developer material and the associated surface charge on an image retention surface for a second value of residual charge retention:
  • FIG. 6 is a chart illustrating the variation in Gamma for different exposure times.
  • FIG. 7 is a characteristic curve of image density versus logarithm of exposure for a halftone reproduction.
  • an electrostatic copying apparatus employing liquid development includes a rotatably mounted drum 8 having an image retention surface comprising, for example, a layer 10 of vitreous or amorphous selenium positioned on an outer surface 11 of the drum.
  • the drum continuously rotates in a counterclockwise direction past a charging electrode 12 which establishes a uniform electrostatic charge on the image retention surface.
  • the charging electrode 12 comprises, for example, a high voltage corona discharge electrode adapted to supply ions or electric charges to the image retention surface.
  • the uniformly charged image retention surface is rotated to an imaging station 13. There is positioned at the imaging station a means for projecting an image on the charged surface for forming a latent electrostatic image conforming to the original image.
  • This means includes a projection system including a lamp 14, a photographic transparency 15 hearing an image which is to be reproduced, and a lens 16 for focussing the image on the uniformly charge surface 10.
  • the latent electrostatic image which is thus formed is rotated by the drum to a development station referenced generally as 11.
  • the latent electrostatic image is developed and is then transported by the drum to an image transfer station 1 8 at which location the image is transferred from the drum to a suitable transfer web 20.
  • the web 20 comprises, for example, a web of liquid developer receptive paper or the like which is fed from a supply roll 22 to a take-up roll 24 and passes between the drum 8 and a transfer roller 26.
  • the image retention surface is rotated past a cleaning station designated generally as g; where residual developer material, if any, is removed by a rotating brush from the drum surface in order to prepare the drum for recycling through the above described operational stations.
  • a developer means is positioned at the development station E for providing liquid development of the latent electrostatic image on the image retention surface 10.
  • the developer means includes a liquid developer dispensing member comprising a rotating drum 30, an inking roller 32 and a reservoir 34 containing developer ink 36.
  • the drum which is described in greater detail hereinafter has deposited on its surface at the inking station a film of ink for transport to the rotating drum 8 and for application to the image retention surface 10.
  • the development ink 36 is withdrawn from the reservoir 34 by the inking roller 32 which is partially submerged in the ink and is conveyed to the drum 30.
  • a doctor blade 38 is mounted on a support 40 and is positioned for bearing against the developer dispensing drum 30 in order to remove excess ink from the dispensing drum 30 after loading and prior to application to the image retention surface.
  • the surface of the developer dispensing drum 30 of FIG. 1 is shown in greater detail in FIGS. 2 and 3.
  • the drum 30 is shown to comprise a metal base having formed on a surface thereof a raised pattern 52 formed, for example, by a plurality of fine raised lines, dots or other geometric configuration.
  • a triangular-helix-patterned gravure applicator drum has been found particularly advantageous in that a two walled structure of a gravure cell of this configuration will yield less overall image background with respect to other wall to wall gravure cell configurations and any tendency for air entrapment in the individual gravure cells is substantially diminished during the inking operation.
  • a particular surface which has been found to be advantageous includes to 200 cells or grooves per linear inch.
  • the pitch is on the order of 5.5 mils and the cell depth is on the order of about 4 mils.
  • the surface of drum 30 is characterized by being wettable by the liquid developer in the depressions or valleys formed between the raised peaks of the raised pattern but substantially non-wettable along the upper surface of the raised lines or peaks. This is accomplished, for example, by the use of a support base 50 having a relatively uniform surface and comprising material that is usually wettable by the liquid developer material employed.
  • FIG. 3 illustrates the developing drum in contact With the image retention surface 10.
  • the image retention surface 10 comprises, for example, a vitreous or amorphous selenium coating 10 which is photosensitive and which is fixed on a metallic drum surface 11.
  • the image retention surface 10 Prior to contact with the developer member 30 the image retention surface 10 bears a latent electrostatic image characterized by a variation in the charge along its surface. This charge pattern, for example, is indicated by the plus signs along its outer surface as viewed in FIG. 3.
  • the surface 10 is brought into contact with the developer dispensing member 30 and the varied lines or dots on the developing dispenser member bear against the surface.
  • Circuit means including a battery 60 and a shunting potentiometer 62 are provided for establishing a developer transfer potential between the image retention surface 10 and the developer member 30.
  • One electrode of the battery 60 is connected to the drum surface 11 while a voltage adjusting arm of the potentiometer is connected to the base 50 of the ink transport member.
  • a voltage adjusting arm of the potentiometer is connected to the base 50 of the ink transport member.
  • an object in halftone format comprises a large number of information elements, while preferably formed as circular dots, can be formed in other suitable configurations. Contrast is established between different subjects in an object by providing variations in the size of information elements in the image.
  • Each of the information elements in a positive halftone object for example, is colored uniformly gray or uniformly black in a monochromatic reproduction system and is separated and distinguishable from adjacent elements by a surrounding buffer area of contrasting white or gray.
  • the buffer areas may alternatively be considered a background field upon which the information elements are formed.
  • a latent electrostatic image is formed on an image retention surface.
  • the latent electrostatic image comprises a corresponding plurality of information elements which are uniformly charged and which conform in number and arrangement to the information elements of the object.
  • the electrostatographic imaging process provides non-imaged areas of relatively high uniform charge on the photoreceptive surface 10 which correspond to the information element areas of the object and have a total area A',,, while the imagead areas which have been partially or fully discharged correspond to the buffer areas of the object.
  • the latent electrostatic information elements and the buffer areas will occupy the same areas as they occupy in the object or will be proportionally enlarged or reduced in size. In any case, the relative areas of the information elements and the surrounding buffer areas in the image are ordinarily proportional to their respective areas in the object.
  • development of the image by transfer of ink to the image retention surface results in the formation of a large number of inked information elements.
  • the development ink initially deposits on charged information elements and will then spread laterally and substantially uniformly along the surface from the information element into a portion of the surrounding buffer area. This lateral flow of ink occurs when a charge, termed the residual charge, having an intensity below a development threshold intensity remains in the incompletely exposed and partially charged buffer area.
  • development threshold is meant a uniform surface charge density or potential of an information element at or above which potential the ink is transferred directly from the development drum 30 to a charged surface.
  • the ink is not transferred directly to the buffer area from the drum 30 but will subsequently transfer laterally into this area A' in accordance with the magnitude of the residual charge in this area after having first been attracted to the highly charged information element area.
  • This lateral transfer characteristic is represented in FIGS. 4 and 5 wherein the threshold voltage, the residual charge level, and the potential for a halftone information element on the image retention surface are indicated.
  • a method for varying the contrast of an image with respect to an object which is presented in halftone format in an electrostatographic copying apparatus is provided by controlling the exposure of the photoreceptive surface during the imaging step.
  • a method for increasing the contrast of an image with respect to an object which is presented in halftone format in an electrostatographic copying apparatus utilizing polar ink developer is provided by controlling the residual charge level on an image retention surface. The control of the residual charge level establishes the extent of lateral movement of the polar developer ink from the information element area into the surrounding buffer areas.
  • the ratio of the total area A; occupied by the information elements in the object to the area A occupied by the buffer area in the object has a value of R
  • the ratio of the total area A in the image to which ink is drawn to the total area to which ink is not drawn A in the image has a value of R
  • a proportionality exists between the total areas occupied by the information elements and the buffer area in the object as well as between the information element areas and the buffer areas in the image. While the area occupied by the information and buffer areas in the image may be larger or smaller than the corresponding areas occupied by the information element and buffer areas in the object, the value of the ratios R and R have heretofore been substantially equal.
  • the ratio R is made different than the ratio R during the imaging process.
  • the contrast between the image and the object is accordingly altered.
  • the relatively highly charged information elements are created by uniformly charging the image retention surface and by exposing and discharging charge in the buffer areas.
  • the exposure of the image retention surface will provide an image having a substantially same contrast as the object.
  • the charge in the buffer areas surrounding the information element areas on the image retention surface will be raised to a level causing the lateral flow of ink from the information element areas into the surrounding areas.
  • the information areas A on the photoreceptive surface will then include the area occupied by the information element A' as well as the inked portion of the bufier area indicated as A
  • the amount of ink flowing into the buffer areas will depend upon the residual charge remaining on the photoconductor surface and can include the entire buffer area associated with an information element when the charge in this area is not materially altered from the level of the charge initially established on a surface to the absence of the flow of ink from the information element area into the buffer area at relatively low levels of residual charge or when the buffer area is fully discharged.
  • the contrast of the image relative to the object can be decreased by providing for the scattering of light into the proportionally imaged information element area at the photoreceptive surface. This can be accomplished by defocusing of the image at the photoreceptive surface.
  • the defocusing will result in the scattering of light into the information element area and will decrease the ratio R
  • FIG. 1 there is illustrated alternative means for varying the exposure of the image reception surface to the object.
  • the lamp 14 which is shown to be an incandescent lamp is energized by current derived from a source of potential shown to be a battery 70. Current from this battery flows to the lamp 14 through a switch 72 and through a current adjusting rheostat 74.
  • the exposure of the surface 10 to the object by closing switch 72 for a predetermined interval of time T will provide a repoduction having a contrast equal to that of the object and the ratios of R and R will be substantially equal.
  • An increase in contrast in the reproduced image with respect to the object is provided by exposing the photoconductor surface for a period of time T which is less than the period of time T
  • the exposure can thus be varied by closing the switch 72 for the interval time T
  • the contrast can be varied by adjusting the illumination of the photoconductive surface for this period of time.
  • the illumination can be altered by adjusting the lamp current through adjustment of the rheostat 74.
  • Rheostat 74 is initially adjusted to provide a lamp current I which in the predetermined interval of time T will provide a reproduction having a contrast equal to the contrast of the object.
  • the rheostat is then adjusted to provide a current I which is generally less in amplitude than the current I and by closing the switch 72 for the predetermined period of time T the image contrast is increased.
  • contrast can be decreased in the reproduced image by non-proportionally reducing the size of the information elements in the image.
  • This can be accomplished by controlling the light whichis ordinarily projected at the surface for forming a proportionally sized image information element.
  • the location lens 16 of FIG. 1 is altered with respect to the transparency 15 and the photoconductive surface 10 in order to cause scattering of light into the area which would be occupied by a proportionally related information element.
  • the scattering is accomplished in a substantially symmetrical manner by the lens with the result that the latent information elements thus formed are non-proportionally related in area to the information element areas in the object.
  • the various methods for altering the location of the lens 16 with respect to the object 15 and the photoreceptive surface 10 are not illustrated. However, the mechanism for preparing lens adjustment are known in the art.
  • a desired variation in contrast between the reproduced image and the object can be effected by a machine operator who controls the exposure of the photoreceptive surface.
  • the operator can vary the exposure from that exposure which will provide a reproduction of equal contrast to the exposure which provides a copy of desired contrast. This can be accomplished manually for example, with the apparatus of FIG. 1 by altering the time of exposure or by altering the amplitude of lamp current.
  • the location of the lens 16 can be also altered in order to effect a change in contrast.
  • an automatic contrast control having a means for sensing the contrast of the object and for causing a variation in the illumination, time of exposure or location of the lens 16 can be provided.
  • Characteristic curves for imaging a halftone original in accordance with the invention are illustrated in FIG. 6. These curves were generated through the use of a halftone original having a 120 screen count, an image retention surface comprising a 15 4 selenium photoreceptor, and employing carbon pigmented mineral oil based ink.
  • An apparatus of the type illustrated in FIG. 3 was employed for exposure and development wherein the development speed was 5 inches per second and a recording sheet comprised Xerox 4024 type paper. The parameters for these characteristic curves is exposure time in seconds.
  • FIG. 6 illustrates a number of gamma curves for exposure of 0.2 through 4 seconds under the recited conditions.
  • the method of this invention is also advantageously employed for the production of halftone images from continuous tone originals. This is accomplished by placing a uniform screen transparency having the desired configuration for projecting circular or other types of information elements in contact with the continuous tone original. The continuous tone original will then be reproduced as a halftone image.
  • a characteristic curve for a halftone production is derived from the curves of FIG. 6. With a screen of 0.6 density and operating characteristics otherwise the same as described with respect to those employed for generating the curves of FIG. 6, then the print density values can be predicted from the curves corresponding to the respective exposures at 0.6 density units on the original density axis. This curve is illustrated in FIG. 7. Since exposure is the product of intensity and time, the exposure axis can be considered as varying light intensity from the original.
  • the method of the present invention is also advantageously used in the reproduction of halftone originals where a desired increase or decrease in print contrast over that of the original is desirable.
  • the production of halftone images from continuous tone originals is advantageously employed in producing lithographic printing masters, for example.
  • a method for providing a halftone reproduction having a contrast dilfering from the contrast of the object comprising the steps of:
  • each of said charged information areas of area A includes an information element area of relatively high uniform charge intensity having an area A' which is proportionally related to the area of the information elements of said original and to which area a polar ink will be electrostatically attracted when disposed near said surface, and, a surrounding area A' having an electrostatic charge of less intensity than said element area, but of a magnitude for establishing force on said polar ink for causing the lateral flow of said polar ink into said area A' from said information element area A' 5.
  • said charged information areas A are established on said image retention surface by subjecting the surface to activating electromagnetic radiation thereby discharging portions of the uniformly charged surface in image configuration.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Wet Developing In Electrophotography (AREA)
US00221669A 1972-01-28 1972-01-28 Contrast control in electrostatic copying utilizing liquid development Expired - Lifetime US3817748A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US00221669A US3817748A (en) 1972-01-28 1972-01-28 Contrast control in electrostatic copying utilizing liquid development
CA155,146A CA991246A (en) 1972-01-28 1972-10-30 Contrast control in electrostatic copying utilizing liquid development
NL7300584A NL7300584A (ja) 1972-01-28 1973-01-15
GB379073A GB1406794A (en) 1972-01-28 1973-01-25 Contrast control in electrostatic copying utilizing liquid development
JP48011802A JPS4885142A (ja) 1972-01-28 1973-01-29

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US00221669A US3817748A (en) 1972-01-28 1972-01-28 Contrast control in electrostatic copying utilizing liquid development

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JP (1) JPS4885142A (ja)
CA (1) CA991246A (ja)
GB (1) GB1406794A (ja)
NL (1) NL7300584A (ja)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921580A (en) * 1974-06-12 1975-11-25 Varian Associates Liquid development of electrostatic images
US3924945A (en) * 1974-12-03 1975-12-09 Xerox Corp Apparatus for inductive imaging with simultaneous polar ink development
DE2531089A1 (de) * 1974-07-12 1976-01-29 Ricoh Kk Elektrophotographisches verfahren und elektrophotographische einrichtung
DE2547137A1 (de) * 1974-10-21 1976-04-22 Ricoh Kk Elektrophotographisches verfahren und einrichtung zu dessen durchfuehrung
US3973954A (en) * 1973-12-28 1976-08-10 Xerox Corporation Imaging method including exposure of photoconductive imaging member through lenticular lens element
US3973953A (en) * 1973-12-28 1976-08-10 Xerox Corporation Imaging method including exposure of photoconductive imaging member through lenticular lens element
US3973955A (en) * 1971-03-29 1976-08-10 Genji Ohno Electrostatic developing method
US3980404A (en) * 1974-07-26 1976-09-14 Xerox Corporation Xerographic apparatus having improved fluid dispensing member
US3991711A (en) * 1972-10-11 1976-11-16 Fuji Xerox Co., Ltd. Electrostatic duplicating method and apparatus utilizing wet-developing
US4023900A (en) * 1972-03-22 1977-05-17 Xerox Corporation Variable speed liquid development electrostatographics apparatus
US4023898A (en) * 1972-03-10 1977-05-17 Research And Development Laboratories Of Ohno Co., Ltd. Electrostatic developing apparatus
US4029826A (en) * 1973-10-09 1977-06-14 Fuji Xerox Co., Ltd. Electrostatic printing method
US4093460A (en) * 1973-09-10 1978-06-06 Weinstein Leonard M Contrast enhancement and small detail blending of photographic images
US4132548A (en) * 1976-08-20 1979-01-02 Minolta Camera Kabushiki Kaisha Process for reproducing images of fine lines or characters of low density
US4202620A (en) * 1976-04-13 1980-05-13 Philip A. Hunt Chemical Corp. Apparatus for liquid development of latent electrostatic images
US4202913A (en) * 1976-04-13 1980-05-13 Philip A. Hunt Chemical Corp. Method for liquid development of latent electrostatic images
FR2454647A1 (fr) * 1979-04-16 1980-11-14 Hunt Chem Corp Philip A Procede, appareil et compositions liquides pour developpement ou formation d'images electrostatiques
US4763370A (en) * 1986-05-30 1988-08-16 Darko Mance Apparatus and method for dyeing sheet articles
US4982692A (en) * 1988-02-16 1991-01-08 Nec Corporation Apparatus for liquid development of electrostatic latent images
US20050063736A1 (en) * 2003-08-20 2005-03-24 Seiko Epson Corporation Liquid development device, image forming apparatus, and image forming system

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973955A (en) * 1971-03-29 1976-08-10 Genji Ohno Electrostatic developing method
US4023898A (en) * 1972-03-10 1977-05-17 Research And Development Laboratories Of Ohno Co., Ltd. Electrostatic developing apparatus
US4023900A (en) * 1972-03-22 1977-05-17 Xerox Corporation Variable speed liquid development electrostatographics apparatus
US3991711A (en) * 1972-10-11 1976-11-16 Fuji Xerox Co., Ltd. Electrostatic duplicating method and apparatus utilizing wet-developing
US4093460A (en) * 1973-09-10 1978-06-06 Weinstein Leonard M Contrast enhancement and small detail blending of photographic images
US4029826A (en) * 1973-10-09 1977-06-14 Fuji Xerox Co., Ltd. Electrostatic printing method
US3973953A (en) * 1973-12-28 1976-08-10 Xerox Corporation Imaging method including exposure of photoconductive imaging member through lenticular lens element
US3973954A (en) * 1973-12-28 1976-08-10 Xerox Corporation Imaging method including exposure of photoconductive imaging member through lenticular lens element
US3921580A (en) * 1974-06-12 1975-11-25 Varian Associates Liquid development of electrostatic images
DE2531089A1 (de) * 1974-07-12 1976-01-29 Ricoh Kk Elektrophotographisches verfahren und elektrophotographische einrichtung
US3980404A (en) * 1974-07-26 1976-09-14 Xerox Corporation Xerographic apparatus having improved fluid dispensing member
DE2547137A1 (de) * 1974-10-21 1976-04-22 Ricoh Kk Elektrophotographisches verfahren und einrichtung zu dessen durchfuehrung
US3924945A (en) * 1974-12-03 1975-12-09 Xerox Corp Apparatus for inductive imaging with simultaneous polar ink development
US4202913A (en) * 1976-04-13 1980-05-13 Philip A. Hunt Chemical Corp. Method for liquid development of latent electrostatic images
US4202620A (en) * 1976-04-13 1980-05-13 Philip A. Hunt Chemical Corp. Apparatus for liquid development of latent electrostatic images
US4132548A (en) * 1976-08-20 1979-01-02 Minolta Camera Kabushiki Kaisha Process for reproducing images of fine lines or characters of low density
FR2454647A1 (fr) * 1979-04-16 1980-11-14 Hunt Chem Corp Philip A Procede, appareil et compositions liquides pour developpement ou formation d'images electrostatiques
US4763370A (en) * 1986-05-30 1988-08-16 Darko Mance Apparatus and method for dyeing sheet articles
US4982692A (en) * 1988-02-16 1991-01-08 Nec Corporation Apparatus for liquid development of electrostatic latent images
US20050063736A1 (en) * 2003-08-20 2005-03-24 Seiko Epson Corporation Liquid development device, image forming apparatus, and image forming system
US7167666B2 (en) * 2003-08-20 2007-01-23 Seiko Epson Corporation Liquid development device, image forming apparatus, and image forming system

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NL7300584A (ja) 1973-07-31
JPS4885142A (ja) 1973-11-12
CA991246A (en) 1976-06-15
GB1406794A (en) 1975-09-17

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