US3815988A - Image density control apparatus - Google Patents

Image density control apparatus Download PDF

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Publication number
US3815988A
US3815988A US00361112A US36111273A US3815988A US 3815988 A US3815988 A US 3815988A US 00361112 A US00361112 A US 00361112A US 36111273 A US36111273 A US 36111273A US 3815988 A US3815988 A US 3815988A
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United States
Prior art keywords
electrostatic latent
latent image
sample
potential
photoconductive surface
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
US00361112A
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English (en)
Inventor
Veigh J Mc
G Tsilibes
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Xerox Corp
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Xerox Corp
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Filing date
Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
Priority to US00361112A priority Critical patent/US3815988A/en
Priority to AR253772A priority patent/AR205710A1/es
Priority to CA193,290A priority patent/CA1036654A/en
Priority to DE2411855A priority patent/DE2411855C3/de
Priority to NL7405155.A priority patent/NL166805C/nl
Priority to JP5216374A priority patent/JPS5536144B2/ja
Priority to FR7416693A priority patent/FR2230003B1/fr
Priority to IT22689/74A priority patent/IT1012346B/it
Priority to BR3928/74A priority patent/BR7403928D0/pt
Priority to GB2177074A priority patent/GB1458707A/en
Priority to ZA00743132A priority patent/ZA743132B/xx
Priority to BE144468A priority patent/BE815209A/xx
Application granted granted Critical
Publication of US3815988A publication Critical patent/US3815988A/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
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0105—Details of unit
    • G03G15/0121—Details of unit for developing
    • 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

  • This invention relates generally to a multi-color electrophotographic printing machine, and more particularly concerns an apparatus for controlling the density of toner particles deposited on a single color electrostatic latent image recorded on a charged photoconductive surface.
  • a photoconductive surface is uniformly charged and exposed to a light image of an original document. Exposure of the photoconductive surface records thereon an electrostatic latent image corresponding to the original document. The electrostatic latent image is then rendered visible by depositing thereon toner particles which adhere electrostatically, in image configuration, thereto. Thereafter, the toner powder image may be transferred to a sheet of support material. The toner powder image is, then, permanently affixed to the support material to provide a copy of the original document.
  • the foregoing process was originally disclosed in U.S. Pat. No. 2,297,691 issued to Carlson in 1942.
  • Multi-color electrophotographic printing is similar to the heretofore discussed process with the following exceptions. Rather than forming a total light image of the original document, the light image is filtered producing a single color light image which is a partial light image of the original.
  • the foregoing single color light image exposes the charged photoconductive surface to record thereon a single color electrostatic latent image.
  • This single color electrostatic latent image is developed with toner particles of a color complementary to the single color light image.
  • the single color toner powder image is transferred to the sheet of support material.
  • the foregoing process is repeated a plurality of cycles with differently colored light images and the respective complementary colored toner particles.
  • Each single color toner powder image is transferred to the support material superimposed in registration with the prior toner powder image to form a composite multilayer powder image thereon.
  • This multi-layered toner powder image is coalesced and permanently affixed to the support material forming a composite image corresponding in color to the original document.
  • the characteristics of the photoconductive surface are critical.
  • the electrical characteristics of the photoconductive surface should remain substantially constant.
  • the electrical characteristics of the photoconductive surfaces will vary with temperature changes or with continuous usage thereof. Hence, it is extremely difficult to maintain substantially the same potential on the photoconductive surface for light images projected thereon having substantially identical intensities.
  • electrophotographic printing machines frequently utilize magnetic brushes to produce viewable toner'powder images on the electrostatic latent image recorded on the photoconductive surface. Toner particles are attracted from the magnetic brush to the charged photoconductive surface.
  • the apparatus includes at least one neutral density sample, illuminating means, toner particle depositing means, and sensing and electrical biasing means.
  • the neutral density sample has a pre-sele cted density corresponding to substantially about a predetermined cut-off density for the single color electrostatic latent image recorded on the photoconductive surface.
  • the illuminating means irradiates the neutral density sample and projects the light image formed thereof onto the charged photoconductive surface. In this way, a sample electrostatic latent image is recorded on the photoconductive surface.
  • the sample electrostatic latent image has a potential intermediate that of the single color electrostatic latent image and the non-image regions of the charged photoconductive surface.
  • the potential of the sample electrostatic latent image recorded on the charged photoconductive surface is detected by the sensing and electrical biasing means.
  • the sensing and electrical biasing means electrically bias the toner particle depositing means to a potential corresponding to that of the sample electrostatic latent image recorded on the charged photoconductive surface.
  • toner particles are deposited on regions of the photoconductive surface having a potential greater than'the potential of the sample electrostatic latent image.
  • FIG. 4 is a schematic circuit diagram for periodically sampling the sensed sample electrostatic latent image potential.
  • FIG. 1 schematically illustrates a multi-color electrophotographic printing machine employing the present invention.
  • the multi-color electrophotographic printing machine shown schematically in FIG. 1 illustrates the various components used to produce multi-color copies from a colored original.
  • the apparatus of the present invention is particularly well adapted for use in an electrophotographic printing machine, it will become evident from the following description that it is equally well suited for use in a wide variety of electrophotographic printing machines, and is not necessarily limited to the particular embodiment shown therein.
  • the printing machine employs a drum 10 having a photoconductive surface 12 secured thereto and entrained about the exterior circumferential surface thereof.
  • Drum 10 is mounted rotatably within the machine frame (not shown).
  • a series of processing stations are positioned such that as drum I rotates in the direction of arrow 14, photoconductive surface 12 passes sequentially therethrough.
  • Drum is driven at a predetermined speed relative to the other machine operating mechanisms by a common drive motor (not shown).
  • One type of suitable photoconductive material is disclosed in US. Pat. No. 3,655,377, issued to Sechak in 1972.
  • a timing wheel is mounted in the region of one end of drum 10 and adapted to trigger the logic circuitry of the printing machine. This coordinates the various machine operations with one another to produce the proper sequence of the events at the appropriate processing stations.
  • drum 10 moves photoconductive surface 12 through charging station A.
  • Charging station A has positioned thereat a corona generating device, indicated generally at 1 6.
  • Corona generating device 16 extends in a generally longitudinal direction transversely across photoconductive surface 12. This readily enables corona generating device 16 to charge photoconductive surface 12 to a relatively high substantially uniform potential.
  • corona generating device 16 is of the type described in US. Pat. No. 2,778,946 issued to Mayo in 1957.
  • Exposure station B includes thereat a moving lens system, generally designated by the reference number 18, and a color filter mechanism shown generally at 20.
  • a suitable moving lens system is disclosed in U.S. Pat. No. 3,062,108 issued to Mayo in 1962, and a suitable color filter mechanism is described in co-pending application Ser. No. 830,282 filed in 1969.
  • Disc 22 has a plurality of neutral density samples (in this case 3) disposed thereon.
  • Disc 22 is mounted rotatably in the printing machine and is disposed beneath transparent platen 24 within the half angle of the optical system. Before the light source lamps indicated generally by the reference numeral 26, begin to scan, they will be actuated to illuminate one of the neutral density samples. In this way,
  • a sample electrostatic latent image is recorded, on photoconductive surface 12 as drum 10 rotates. Lamps 26 are stationary and the appropriate filter is positioned in filter 20 forming a sample electrostatic latent image on photoconductive surface I2 which is a strip discharged to the desired potential.
  • the potential of the sample electrostatic latent image recorded on photoconductive surface 12 is detected by probe 28, i.e. a suitable electrometer disposed adjacent to photoconductive surface 12 intermediate exposure station 8 and development station C.
  • the electrical output signal from probe 28 is processed by circuit elements 30 which regulate voltage source or power supply 84 adjusting the bias voltage of the respective developer unit having toner particles complementary in color to the filter of filter mechanism 20.
  • disc 22 includes three equally spaced neutral density samples located about the periphery thereof.
  • Sample 32 is a neutral density sample for green separation
  • sample 34 is a neutral density sample for red separation
  • sample 36 is a neutral sample for blue separation.
  • the green separation sample has a density of 0.32
  • the blue separation sample a density of 0.35
  • the red separation sample a density of 0.15.
  • the appropriate neutral density sample is illuminated by light source 26 to produce a sample electrostatic image corresponding to a predetermined development density for the filter being used, i.e. a green filter will have neutral density sample 32 illuminated forming a sample electrostatic latent image corresponding to the predetermined development density for the green separation.
  • a single color light image exposes the charged photoconductive surface.
  • the potential on the charged photoconductive surface in the area irradiated by the single color light image is reduced.
  • the potential of the charged photoconductive surface in the non-irradiated areas remain substantially unchanged.
  • toner particles complementary in color to the single color light image, are deposited on the photoconductive surface.
  • the irradiated areas remain substantially devoid of toner particles.
  • the development system is biased such that the potential thereof is intermediate the irradiated and non-irradiated areas.
  • toner particles are attracted to the non-irradiated areas from the development system since the potential of the nonirradiated areas is greater than the potential of the development system, whereas toner particles are not attracted to the irradiated areas inasmuch as the charge thereof is less thin than that of the development system.
  • Each of the neutral density samples form a sample electrostatic latent image.
  • the charge of the sample electrostatic latent image is greater than that of the irradiated areas and less than that of the non-irradiated areas.
  • the developer unit is adjusted to the potential of the sample electrostatic latent image.
  • toner particles are attracted to all regions of the charged photoconductive surface having a potential greater than that of the sample electrostatic latent image.
  • the potential of the sample electrostatic latent image corresponds to the washout density of the single color toner powder image, i.e. the potential beneath which development of the single color electrostatic latent image does not occur. However, if the potential of the single color electrostatic latent image is greater than that of the sample electrostatic latent image development will occur.
  • an original document 25 such as a book, sheet of paper, or the like, disposed upon transparent viewing platen 24 is scanned.
  • Lamps 26 and lens 18 move in a timed relation with drum to scan successive incremental areas of original document 25 disposed upon platen 24. This creates a flowing light image of original document 25 which is projected onto charged photoconductive surface 12.
  • Filter mechanism 20 is adapted to interpose selected color filters into the optical light path. The appropriate color filter operates on the light rays passing through lens 18 to record an electrostatic latent image on photoconductive surface 12 corresponding to a preselected spectral region of the electromagnetic wave spectrum, heretofore referred to as a single color electrostatic latent image.
  • drum 10 rotates the single color electrostatic latent image recorded on photoconductive surface 12 to development station C.
  • Development station C includes thereat three individual developer units, generally indicated by the reference numerals 38, 40, and 42.
  • a suitable development system employing a plurality of developer units is disclosed in co-pending application Ser. No. 255,259, filed in 1970.
  • the developer units are all of a type generally referred to as magnetic brush developer units.
  • a typical magnetic brush developer unit utilizes a magnetizable developer mix having carrier granules and toner particles. The developer mix is continually brought through a directional flux field to form a brush thereof.
  • Each developer unit includes a developer roll 86, 88 and 90 (FIG.
  • the potential applied to the developer roll is substantially equal to that of the sample electrostatic latent image recorded on photoconductive surface 12 and detected by probe 28.
  • the single'color electrostatic latent image recorded on photoconductive surface 12 is developed by bringing the brush of developer mix into contact therewith.
  • Each of the respective developer units contain discretely colored toner particles corresponding to the complement of the spectral region of the wavelength of light transmitted through filter 21, e.g. a green filtered electrostatic latent image is rendered visible by depositing green absorbing magenta toner particles therein, blue and red latent images are developed with yellow and cyan toner particles, respectively.
  • Drum 10 is, next, rotated to transfer station D where the toner powder image adhering electrostatically to photoconductive surface 12 is transferred to a sheet of final support material 44.
  • Support material 44 may be plain paper, or a sheet of transparent, thermoplastic material.
  • a transfer roll shown generally at 46, rotates support material 44 in the direction of arrow 48.
  • Transfer roll 46 is electrically biased to a potential of sufficient magnitude and polarity to electrostatically attract toner particles from photoconductive surface 12 to support material 44.
  • U.S. Pat. No. 3,612,677 issued to Langdon et al. in 1972, discloses a suitable electrically biased transfer roll. Transfer roll 46 is arranged to rotate in synchronism with drum 10, Le.
  • transfer roll 46 and drum l0 rotate at substantially the same angular velocity and have substantially the same outer diameter.
  • support material 44 is secured to transfer roll 46 for movement therewith in a recirculating path, successive toner powder images may be transferred from photoconductive surface 12 to support material 44, in superimposed registration with one another.
  • a multi-color toner powder image corresponding in color to the original document is formed on support material 44.
  • a stack 50 of support material 44 is supported on tray 52.
  • Feed roll 54 operatively associated with retard roll 56, separates and advances the uppermost sheet from stack 50.
  • the advancing sheet moves into chute 58 and is directed into the nip of register rolls 60.
  • gripper fingers 62 mounted on transfer roll 46, releasably secure thereto support material 44 for movement therewith in a recirculating path.
  • gripper fingers 62 space support material 44 from transfer roll 46. This enables stripper bar 64 to be interposed between support material 44 and transfer roll 46 separating support material 44 therefrom. After support material 44 is stripped from transfer roll 46, it is moved on endless belt conveyor 66 to fixing station E.
  • a suitable fuser indicated generally at 68, coalesces and permanently affixes the toner powder image to support material 44.
  • a typical fuser is described in U.S. Pat. No. 3,498,592 issued to Moser et al. in 1970.
  • endless belt conveyors 68 and 70 advance support material 44 to catch tray 72.
  • Catch tray 72 is readily accessible so that an operator may remove the final multi-color copy from the printing machine.
  • residual toner particles remain on photoconductive surface 12 after the transfer of the toner powder image therefrom to support material 44. These residual toner particles are removed from photoconductive surface 12 as it passes through cleaning station F. At cleaning station'F, residual toner particles are initially brought under the influence of a cleaning corona generating device (not shown) adapted to neutralize the electrostatic charge remaining on the residual toner particles and photoconductive surface. The neutralized toner particles are then removed from photoconductive surface 12 by rotatably mounted brush 76.
  • a suitable brush cleaning device is described in U.S. Pat. No. 3,590,412 issued to Gerbasi in 1971. Brush 76 is positioned at cleaning station F and maintained in contact with photoconductive surface 12. Thus, the residual toner particles remaining on photoconductive surface 12, after each successive transfer operation, are readily removed therefrom.
  • lamp carriage 78 supporting a pair of light sources or lamps 26 thereon.
  • Lamp carriage 78 is arranged to traverse platen 24 illuminating incremental widths of original document 25 disposed therein.
  • a suitable belt drive system advances lamp carriage 78 in the direction of arrow 80 to scan successive incremental areas of the original document 25 and returns lamp carriage 78 in the direction of arrow 82 to the initial position.
  • Disc 22 is mounted rotatably on the printing machine frame and is interposed between lamp carriage 78 and platen 24.
  • disc 22 is indexed so that light source 26 illuminates one of the neutral density samples disposed thereon. For example,
  • neutral density sample 32 is shown in position to be illuminated.
  • Light source 26 remains stationary as drum 10 rotates so that a sample electrostatic Iatent image corresponding in density to the neutral density sample is recorded on photoconductive surface 12.
  • Probe 28 is secured in the machine frame and positioned between exposure station B and development station C. Probe 28 is seated within the machines support housing and arranged to detect the sample electrostatic latent image recorded on photoconductive surface 12. A light image of the neutral density sample is projected onto the charged photoconductive surface recording a sample electrostatic latent image thereon. The sample electrostatic latent image is detected by probe 28.
  • the machine logic is arranged to generate a signal during each print cycle initiating the formation of the sample electrostatic latent image. In practice, the signal is generated when light source 26 is in the initial position prior to scanning of original document 25.
  • a voltage indicative of the sample electrostatic latent image is sensed by probe 28 and processed by electrical circuitry 30 to produce an electrical output signal regulating voltage source or variable power supply 84.
  • Power supply 84 is operatively connected to developer rolls 86, 88 and 90, respectively, of the corresponding developer units 38, 40, and 42.
  • Power supply 84 regulates the electrical potential applied to the respective developer rolls 86, 88 and 90.
  • each of the developer rolls is selectively biased to a potential substantially identical to that of the appropriate sample electrostatic latent image potential recorded on photoconductive surface 12.
  • the developer roll potential is intermediate photoconductive the potential of the irradiated and non-irradiated areas in photoconductive surface 12.
  • the signal generated by the machine logic has a pulse of sufficient duration to de-energize the drive of lamp carriage 78 when light source 26 is in the initial position. This enables disc 22 to index such that a neutral density sample is illuminated by light source 26. The resulting light image thereof is projected onto the moving photoconductive surface forming the sample electrostatic latent image thereon.
  • a second pulse of sufficient duration is generated by the machine logic actuating the drive system of lamp carriage 78 so that light source 26 illuminates incremental portions of original document 25 as it moves thereacross. This creates a single color electrostatic latent image on photoconductive surface 12 after the corresponding sample electrostatic latent image is recorded thereon.
  • Probe 28 senses the potential of the sample electrostatic latent image and develops a voltage signal indicative thereof.
  • the voltage signal from probe 28 is processed by unity gain amplifier 92.
  • a suitable amplifier having a high impedance can be utilized in conjunction with the probe of the present invention.
  • the electrical output from amplifier 92 is transmitted through two successive amplifier stages 94 and 96, and then applied to a hold circuit including a high impedance unity gain amplifier 98 and a capacitor 100.
  • the signal is initially prevented from passing to the hold circuit by normally open contact 102.
  • probe 28 includes a sensing element 104 surrounded by an insulator 106.
  • Insulator 106 is preferably fabricated from a material which is electrically insensitive to humidity changes and functions to maintain a high probe-to-ground resistance.
  • Conductive shield 108 is disposed around insulator 106 and the output from amplifier 92 is fed back to shield 108. This maintains shield 108 at the same potential as amplifier 92 reducing current leakage from sensing element 104 to the surrounding electrical ground.
  • the machine logic preferably, includes suitable circuitry adapted to close contact at the appropriate time. Thus, the sample voltage is applied across the high impedance unity gain amplifier 98. Closing contact 102 causes two discrete conditions to occur.
  • the sensed sample electrostatic latent image potential is applied across the high impedance amplifier 98 and secondarily, capacitor 100, in the hold circuitry, is charged to the sample electrostatic latent image potential. Termination of the signal from the machine logic after thesample electrostatic latent image has passed probe 28 permits contact v102 to return to its normally open position. However, the sample electrostatic latent image potential is stored on capacitor 100 and continues to be impressed across amplifier 98. Because of the high impedance of amplifier 98, a relatively constant output is maintained during the hold periods until the subsequent reclosing of contacts 102 provides a new sample electrostatic latent image potential. This output voltage is applied to power supply 84 (FIG. 3) holding the output voltage therefrom substantially constant until the next sample signal is received thereby.
  • capacitor 100 is allowed to recharge to the new potential through contact 102 and through the circuitry of amplifier 96.
  • the new sample electrostatic latent image potential is impressed across the high-impedance hold amplifier 98 and capacitor 100 is recharged to this new voltage.
  • the output voltage is supplied to power supply high-voltage operational amplifier which holds the voltage output from power supply 84 substantially constant until the next signal is received.
  • contact 102 is again open and the hold circuit waits for the next sample.
  • this type of arrangement permits the present apparatus to detect both increases and decreases in the potential of the sample electrostatic latent image recorded on photoconductive surface 12 while, substantially simultaneously therewith, generating a continuous control signal for regulating the potential applied to developer rolls 86, 88 and 90 of developer units 38, 40 and 42, respectively.
  • the apparatus of the present invention controls the cut-off density of toner particles deposited on a single color electrostatic latent image recorded on a charged photoconductive surface. This is achieved by exposing the charged photoconductive surface to a neutral density sample having a pre-selected density corresponding to substantially about the predetermined cut-off density of the single color electrostatic latent image. In this way, a sample electrostatic latent image is recorded on the photoconductive surface.
  • the potential of the sample electrostatic latent image is employed to electrically bias the developer roll of the corresponding magnetic brush developer unit to substantially the same potential.
  • toner particles are attracted to those regions of the photoconductive surface having a potential greater than that of the sample electrostatic latent image. Inasmuch as the potential of the non-image region is substantially less than that of the image region, toner particles are not attracted thereto and the image region of photoconductive surface 12 has toner particles deposited thereon.
  • An apparatus for controlling the cut-off density of toner particles deposited on a single color electrostatic latent image recorded on a charged photoconductive surface including:
  • At least one neutral density sample having a preselected density corresponding to substantially about the predetermined cut-off density of the single color electrostatic latent image
  • toner particle depositing means for sensing the potential of the sample electrostatic latent image recorded on the charged photoconductive surface and electrically biasing said toner particle depositing means to a potential corresponding to the sample electrostatic latent image potential so that toner particles are deposited on regions of the photoconductive surface having a potential substantially greater than the potential of the sample electrostatic latent image.
  • sensing and biasing means includes;
  • a probe positioned adjacent to the photoconductive surface and arranged to detect the potential of the sample electrostatic latent image recorded thereon prior to toner particles being deposited on the photoconductive surface;
  • means in electrical communication with said probe and said voltage source, for generating an electrical output signal indicative of the sample electrostatic latent image potential detected by said probe to regulate the output voltage of said voltage source.
  • circuit means for analyzing the periodically detected sample electrostatic latent image potential and forming a continuous electrical output signal indicative thereof
  • An electrophotographic printing machine of the type having a photoconductive surface including:
  • At least one neutral density sample having a preselected density corresponding to substantially about the predetermined cut-off density of the single color electrostatic latent image
  • exposing means for exposing the charged photoconductive surface to a single color light image of an original document to record thereon a single color electrostatic latent image said exposing means being arranged to illuminate said neutral density sample and project a light image thereof onto the charged photoconductive surface to record thereon a sample electrostatic latent image having a potential intermediate the single color electrostatic latent image and the non-image regions of the charged photoconductive surface;
  • toner particle depositing means for sensing the potential of the sample electrostatic latent image recorded on the charged photoconductive surface and electrically biasing said toner particle depositing means to a potential corresponding to the sample electrostatic latent image potential so that toner particles are deposited on regions of the photoconductive surface having a potential substantially greater than the potential of the sample electrostatic latent image.
  • sensing and biasing means includes:
  • a probe positioned adjacent to the photoconductive surface and arranged to detect the potential of the sample electrostatic latent image recorded thereon prior to toner particles being deposited on the photoconductive surface;
  • means in electrical communication with said probe and said voltage source, for generating an electrical output signal indicative of the sample electrostatic latent image potential detected by said probe to regulate the output voltage of said voltage source.
  • said electrical signal generating means includes means for periodically sampling the sample electrostatic image potential detected by said probe;

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Color Electrophotography (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
  • Developing For Electrophotography (AREA)
  • Dry Development In Electrophotography (AREA)
US00361112A 1973-05-17 1973-05-17 Image density control apparatus Expired - Lifetime US3815988A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US00361112A US3815988A (en) 1973-05-17 1973-05-17 Image density control apparatus
AR253772A AR205710A1 (es) 1973-05-17 1974-01-01 Aparato para controlar la densidad de corte de particulas viradoras
CA193,290A CA1036654A (en) 1973-05-17 1974-02-22 Image density control apparatus
DE2411855A DE2411855C3 (de) 1973-05-17 1974-03-12 Einrichtung zum Steuern des Potentials der Entwicklerelektrode
NL7405155.A NL166805C (nl) 1973-05-17 1974-04-16 Beelddichtheidsbesturingsinrichting.
JP5216374A JPS5536144B2 (nl) 1973-05-17 1974-05-10
FR7416693A FR2230003B1 (nl) 1973-05-17 1974-05-14
IT22689/74A IT1012346B (it) 1973-05-17 1974-05-14 Apparecchiatura per il controllo della densita di immagine e macchi na da stampa elettrofotografica che la comprend
BR3928/74A BR7403928D0 (pt) 1973-05-17 1974-05-15 Aparelho para controle da densidade de imagem e maquina de copia eletrografica que engloba e mesmo
GB2177074A GB1458707A (en) 1973-05-17 1974-05-16 Image density control apparatus
ZA00743132A ZA743132B (en) 1973-05-17 1974-05-16 Image density control apparatus
BE144468A BE815209A (fr) 1973-05-17 1974-05-17 Appareil de commande de la densite de seuil d'une image et machine utilisant cet appareil

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00361112A US3815988A (en) 1973-05-17 1973-05-17 Image density control apparatus

Publications (1)

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US3815988A true US3815988A (en) 1974-06-11

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US00361112A Expired - Lifetime US3815988A (en) 1973-05-17 1973-05-17 Image density control apparatus

Country Status (12)

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US (1) US3815988A (nl)
JP (1) JPS5536144B2 (nl)
AR (1) AR205710A1 (nl)
BE (1) BE815209A (nl)
BR (1) BR7403928D0 (nl)
CA (1) CA1036654A (nl)
DE (1) DE2411855C3 (nl)
FR (1) FR2230003B1 (nl)
GB (1) GB1458707A (nl)
IT (1) IT1012346B (nl)
NL (1) NL166805C (nl)
ZA (1) ZA743132B (nl)

Cited By (27)

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US3892481A (en) * 1974-06-17 1975-07-01 Savin Business Machines Corp Automatic development electrode bias control system
US3936182A (en) * 1974-08-12 1976-02-03 Xerox Corporation Control arrangement for an electrostatographic reproduction apparatus
US3960444A (en) * 1974-08-14 1976-06-01 Xerox Corporation Electrophotographic printing machine
US4045218A (en) * 1974-03-29 1977-08-30 Xerox Corporation Method for electrostatically producing a color accented photocopy
US4093457A (en) * 1976-06-10 1978-06-06 Xerox Corporation Method of transfer
DE2756291A1 (de) * 1976-12-31 1978-07-13 Xerox Corp Steuereinrichtung fuer ein elektrostatographisches kopiergeraet
US4106870A (en) * 1973-12-28 1978-08-15 Canon Kabushiki Kaisha Color electrophotographic method and apparatus
US4128329A (en) * 1975-10-03 1978-12-05 Ricoh Company, Ltd. Apparatus for producing bias voltage for use in electrophotographic copying machines
US4248527A (en) * 1978-01-17 1981-02-03 Konishiroku Photo Industry Co., Ltd. Apparatus for controlling toner concentration in electrophotographic copying machines
EP0037711A2 (en) * 1980-04-07 1981-10-14 Xerox Corporation Method and apparatus for controlling a reproduction machine
US4403848A (en) * 1982-02-17 1983-09-13 Xerox Corporation Electronic color printing system
DE3412268A1 (de) * 1983-04-01 1984-10-04 Canon K.K., Tokio/Tokyo Bilderzeugungseinrichtung
US4505572A (en) * 1981-10-30 1985-03-19 Konishiroku Photo Industry Co., Ltd. Electrostatic reproducing apparatus
USRE31964E (en) * 1974-06-17 1985-08-06 Savin Corporation Automatic development electrode bias control system
US4607944A (en) * 1985-06-07 1986-08-26 Eastman Kodak Company Apparatus for controlling toner replenishment in electrographic copier
USRE32330E (en) * 1977-02-23 1987-01-13 Ricoh Co., Ltd. Method of maintaining the correct conditions of an electrophotographically duplicated image
DE3628853A1 (de) * 1985-08-31 1987-03-19 Ricoh Kk Bildaufzeichnungsgeraet
DE3644355A1 (de) * 1985-12-24 1987-07-30 Toshiba Kawasaki Kk Bilderzeugungsvorrichtung
US4736223A (en) * 1980-12-16 1988-04-05 Canon Kabushiki Kaisha Color copying machine
WO1988003670A1 (en) * 1986-11-06 1988-05-19 Eastman Kodak Company Dynamic feedforward process control for electrographic machines
US4780744A (en) * 1987-02-18 1988-10-25 Eastman Kodak Company System for quality monitoring and control in an electrophotographic process
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US4106870A (en) * 1973-12-28 1978-08-15 Canon Kabushiki Kaisha Color electrophotographic method and apparatus
US4045218A (en) * 1974-03-29 1977-08-30 Xerox Corporation Method for electrostatically producing a color accented photocopy
USRE31964E (en) * 1974-06-17 1985-08-06 Savin Corporation Automatic development electrode bias control system
US3892481A (en) * 1974-06-17 1975-07-01 Savin Business Machines Corp Automatic development electrode bias control system
US3936182A (en) * 1974-08-12 1976-02-03 Xerox Corporation Control arrangement for an electrostatographic reproduction apparatus
US3960444A (en) * 1974-08-14 1976-06-01 Xerox Corporation Electrophotographic printing machine
US4128329A (en) * 1975-10-03 1978-12-05 Ricoh Company, Ltd. Apparatus for producing bias voltage for use in electrophotographic copying machines
US4093457A (en) * 1976-06-10 1978-06-06 Xerox Corporation Method of transfer
DE2756291A1 (de) * 1976-12-31 1978-07-13 Xerox Corp Steuereinrichtung fuer ein elektrostatographisches kopiergeraet
USRE32330E (en) * 1977-02-23 1987-01-13 Ricoh Co., Ltd. Method of maintaining the correct conditions of an electrophotographically duplicated image
US4248527A (en) * 1978-01-17 1981-02-03 Konishiroku Photo Industry Co., Ltd. Apparatus for controlling toner concentration in electrophotographic copying machines
EP0037711A3 (en) * 1980-04-07 1982-07-21 Xerox Corporation Method and apparatus for controlling a reproduction machine
EP0037711A2 (en) * 1980-04-07 1981-10-14 Xerox Corporation Method and apparatus for controlling a reproduction machine
US4736223A (en) * 1980-12-16 1988-04-05 Canon Kabushiki Kaisha Color copying machine
US4505572A (en) * 1981-10-30 1985-03-19 Konishiroku Photo Industry Co., Ltd. Electrostatic reproducing apparatus
US4403848A (en) * 1982-02-17 1983-09-13 Xerox Corporation Electronic color printing system
DE3412268A1 (de) * 1983-04-01 1984-10-04 Canon K.K., Tokio/Tokyo Bilderzeugungseinrichtung
US4970536A (en) * 1984-07-27 1990-11-13 Konishiroku Photo Industry Co., Ltd. Apparatus for multicolor image forming wherein image forming conditions are adjusted based on reference images
US4803514A (en) * 1984-10-22 1989-02-07 Konishiroku Photo Industry Co., Ltd. Multi-color image forming method and apparatus
US4607944A (en) * 1985-06-07 1986-08-26 Eastman Kodak Company Apparatus for controlling toner replenishment in electrographic copier
DE3628853A1 (de) * 1985-08-31 1987-03-19 Ricoh Kk Bildaufzeichnungsgeraet
US4737821A (en) * 1985-08-31 1988-04-12 Ricoh Corporation Colored image recording device
DE3644355A1 (de) * 1985-12-24 1987-07-30 Toshiba Kawasaki Kk Bilderzeugungsvorrichtung
WO1988003670A1 (en) * 1986-11-06 1988-05-19 Eastman Kodak Company Dynamic feedforward process control for electrographic machines
US4806980A (en) * 1986-11-06 1989-02-21 Eastman Kodak Company Dynamic feedforward process control for electrographic machines
US4780744A (en) * 1987-02-18 1988-10-25 Eastman Kodak Company System for quality monitoring and control in an electrophotographic process
US5124750A (en) * 1989-09-05 1992-06-23 Minolta Camera Kabushiki Kaisha Toner density detecting method, and image forming method and apparatus employing the toner density detecting method
US5153658A (en) * 1991-08-09 1992-10-06 Xerox Corporation Mac cleaner brush film control
US5329339A (en) * 1991-08-29 1994-07-12 Minolta Camera Kabushiki Kaisha Laser beam printer capable of forming line images having stable image width
US5328787A (en) * 1993-05-24 1994-07-12 Eastman Kodak Company Method for assessing and controlling the sensitometric characteristics of photographic products

Also Published As

Publication number Publication date
JPS5020730A (nl) 1975-03-05
BE815209A (fr) 1974-09-16
AR205710A1 (es) 1976-05-31
FR2230003A1 (nl) 1974-12-13
JPS5536144B2 (nl) 1980-09-18
NL166805C (nl) 1981-09-15
DE2411855A1 (de) 1974-12-05
CA1036654A (en) 1978-08-15
DE2411855B2 (de) 1978-10-12
NL7405155A (nl) 1974-11-19
ZA743132B (en) 1975-05-28
NL166805B (nl) 1981-04-15
DE2411855C3 (de) 1979-06-21
GB1458707A (en) 1976-12-15
IT1012346B (it) 1977-03-10
FR2230003B1 (nl) 1976-12-24
BR7403928D0 (pt) 1975-01-21

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