US3911861A - Programmable toner concentration control - Google Patents

Programmable toner concentration control Download PDF

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Publication number
US3911861A
US3911861A US421226A US42122673A US3911861A US 3911861 A US3911861 A US 3911861A US 421226 A US421226 A US 421226A US 42122673 A US42122673 A US 42122673A US 3911861 A US3911861 A US 3911861A
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Prior art keywords
toner
area
developer
sensing
potential
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Expired - Lifetime
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US421226A
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English (en)
Inventor
Jerome John Griesmer
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AB Dick Co
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Multigraphics Inc
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Application filed by Multigraphics Inc filed Critical Multigraphics Inc
Priority to US421226A priority Critical patent/US3911861A/en
Priority to CA212,596A priority patent/CA1034184A/fr
Priority to GB48048/74A priority patent/GB1483471A/en
Priority to GB3244/77A priority patent/GB1483472A/en
Priority to DE19742456936 priority patent/DE2456936A1/de
Priority to FR7439536A priority patent/FR2253233B1/fr
Application granted granted Critical
Publication of US3911861A publication Critical patent/US3911861A/en
Anticipated expiration legal-status Critical
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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
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
    • G03G15/0848—Arrangements for testing or measuring developer properties or quality, e.g. charge, size, flowability
    • G03G15/0849—Detection or control means for the developer concentration
    • G03G15/0855—Detection or control means for the developer concentration the concentration being measured by optical means

Definitions

  • a toner concentration control including a programmable toner pickup with surface areas at se- 52 us. c1. 118/7- 11s/11- 118/637 acted electrical Potentials Simulate background 51 Int. Cl. BO SC 11/00 and image areas a predetermined image BY 52 Field 01 Search 118/7, 9, 10, 11, 637; Changing the POtemial applied to each of the Pickup 1 17/175 surface areas, the simulated conditions and copy density may be adjusted.
  • This invention relates to electrostatic copying and, more particularly, to an improvement in automatically controlling the concentration of the toner component in a developer mix applied to elcctrostatically imaged copies.
  • Electrostatic copying comprises the steps of charging a photoconductive surface, exposing the charged photoconductive surface to a pattern of light and shadow representative of the graphic information to be copied, developing the resultant charge pattern which corresponds to the graphic information by applying a charge attractable toner powder to the photoconductors surface; and causing the toner powder to be fixed to the photoconductive surface in the areas where the image is desired.
  • developer mixes are made up of toner particles and larger carrier particles and the materials selected are such that the rubbing contact between the dissimilar particles will generate the necessary and appropriate triboelectric charge. Under the influence of the triboelectric forces the toner particles cling to the carrier particles until separated therefrom by a greater attractive force.
  • the developer mix can be flowed, brushed or cascaded over the differentially charged surface which provides the attractive force to separate the toner from the carrier and to attract the toner to the areas which are to be rendered visible.
  • the charge level on the surface to be developed Since the toners are electroscopic materials, they respond to differences in potentials in a given charge pattern.
  • the image and nonimage areas correspond to the pattern of light and shadow generated from the graphic subject matter to be reproduced and compete with each other to attract the toner particles. Small differences between image and non-image areas will produce less attraction to the image areas, while greater differences provide greater attraction of the electroscopic materials toward the image areas.
  • the nature of the charge pattern on the photoconductive materials is important.
  • the amount of toner attracted to the latent image is dependent upon the degree of darkness at any particular point of the image and the ratio of that darkness to the lightness throughout the entire image. More toner will be deposited in an area where the image is extremely dark than in an equal area which is only moderately dark.
  • a number of control systems have been proposed to automatically sense and regulate the concentration of toner powder at a developing station.
  • One such device utilizing an electrical resistance measurement to con trol toner concentration is further described in U.S. Pat. No. 3,527,651.
  • Another such device using an induetivc probe is described in U.S. Pat. No. 3,707,134.
  • Still other devices use optical sensing of light reflected from a probe or capacitive change ofa probe in the developer mix to control the concentration.
  • these devices met with only marginal success and were ineffective in maintaining acceptable copy density. This was particularly true when the mix aged considerably. Ageing often causes changes in the characteristics of the mix, such that the signals provided by these devices are not truly representative of the toner concentration.
  • U.S. Pat. No. 3,348,521 discloses a device which uses a photoconductive surface of extended length on a drum with a permanent electrostatic image thereon located outside the area necessary to develop copies, but still within the operating zone of the developing apparatus.
  • the photoconductive surface is periodically developed and cleaned along with the image area and a photosensor is provided which detects the optical density of the deposited toner.
  • This arrangement generally provides only marginally satisfactory results and has a number of deficiencies.
  • the photoconductive surface is provided with a permanent electrostatic image which is not readily changeable to compensate for different image and background conditions.
  • toner is removed from the system, thereby increasing the amount of toner which has to be added to the mix to maintain a satisfactory concentration.
  • this type of system cannot be adjusted to simulate different image pattern conditions and its operation continually depleats toner from the developer mix.
  • the system is not capable of adjusting for changed signal strength due to contaminants on the image surface.
  • Another object of the present invention is to provide a versatile toner concentration sensing system including a sensing member having separate surface areas with different electrical potentials applied thereto, corresponding to image and background areas, respectively, to accurately simulate a latent image pattern.
  • Still a further object of the present invention is to provide a toner concentration sensing system including a sensing member which is periodically developed and cleaned independently of the latent image pattern and without depleating the toner from the developer mix.
  • It is still another object of the present invention to provide a versatile toner concentration sensing system including a sensing member which is in operative engagement with the developer toner applicator, whereby the sensor member is developed in the same manner as the latent image pattern on the photoconductor, but is subsequently cleaned independently of the photoconductor in a manner which returns the toner directly to the mix.
  • Yet a further object of the present invention is to provide a unique toner concentration sensing system which automatically adjusts for changes in signal strength due to contaminants on the sensing member or changes in reflectivity thereof over a period of time.
  • FIG. 1 is a diagrammatic illustration of the sensor of the present invention utilized with a magnetic brush type developer.
  • FIG. 2 is a partial plan view of the sensor member in operative engagement with a magnetic brush and mounted adjacent to a photosensor unit.
  • FIG. 3 is a diagrammatic illustration and flow diagram of the circuitry associated with the present invention.
  • FIG. 4 is a graphical illustration of the relationship of the electrical potential applied to the sensing Wheel they vary with time.
  • FIG. 5a is a developed view of the sensing wheel showing the toned and cleaned areas defined by applying potential in a preferred arrangement as a function of time.
  • FIG. 5b is a developed view of the sensing wheel as showing a toned and cleaned area defined by applying potential in a second manner as a function of time.
  • a recording member 10 such as a photoconductor in the form ofa cylinder, is shown in contact with developer mix 12 carried by a magnetic brush 14.
  • the magnetic brush 14 applies toner from developer mix 12 onto the charged latent image pattern on the recording member in a well-known manner.
  • U.S. Pat. Nos. 3,003,462 and 3,145,122 describe more fully the operation of the magnetic brush 14.
  • brush 14 is brought into engagement with mix stored in a trough or container 13, whereby the developer mix is replenished on each revolution.
  • both the LII recording member 10 and the magnetic brush 14 are of generally cylindrical configuration.
  • a sensing wheel, or toner pickup, 18 is provided which makes operative contact with the mix carried by magnetic brush 14, but is spaced from the recording member 10.
  • An optical read head 20 is positioned to detect changes in concentration of toner deposited on the sensing wheel 18.
  • an electrostatic image of the copy to be made is produced on the recording member 10 according to techniuqes known in the prior art.
  • Developer mix as previously described, is picked up by the magnetic brush 14 by an appropriate method well-known in the art.
  • the recording member 10 rotates about its axis 11, it makes contact with mix carried by brush 14, such that toner powder is attracted to the image areas on the recording member 10. In this manner, the image of the copy to be made is completely developed by the toner transferred from magnetic brush 14.
  • Transfer of toner is caused by the attraction of charged toner particles to imaged or non-imaged areas of a photosensitive surface.
  • the photosensitive surface must be charged uniformly and then selectively discharged in the desired non-image areas.
  • the toner developer powder which consists of carrier particles, i.e., iron fillings or glass beads, and toner particles is applied to the photoconductive surface.
  • the actual polarity of the charges presented by the toner developer powder and the photosensitive surface is not extremely important. However, the polarity of the toner powder charge must be opposite to the polarity of the charged surface in the area where toner is desired to be deposited. Along these lines, positive and reversal images may be obtained depending upon the polarities chosen for the toner developer and the image.
  • Toner response is a term which may be used to express the relative quantity of toner particles which actually become attracted to the charged image. More particularly, this may be expressed in terms of the mass of toner per unit area. If the image and potential thereof are held constant, the amount of toner attracted to the image area depends upon the concentration of toner in the developer mix.
  • the system of the present invention detects the amountof toner deposited on an image area at a selected potential and causes toner to be added to the mix when the detected toner concentration reaches a predetermined minimum level. Thus, the system is responsive to the mass of toner deposited per unit area.
  • the sensing wheel 18 will be subjected to the developer mix on the surface of the magnetic brush 14. If a charge pattern, analogous to that of an image, is present on the sensing wheel I8, toner powder will be attracted to the sensing wheel. However, when no charge pattern is present on the sensing wheel 18, no toner powder will be attracted.
  • a charge pattern analogous to a particular image may be synthesized.
  • voltages are applied to the sensing wheel 18 to establish potential differences representative of a selected image pattern.
  • These potential differences result in charge patterns which attract toner particles and develop selected image depending upon the polarity of the charge patterns and the toner.
  • the selected potential established on the sensing wheel 18 represent variations of possible image densities. That is, the sensing wheel l8 is capable of simulating varying degrees of image lightness or darkness in addition to a range of background conditions. Potential differences applied to the sensing wheel 18 are arranged to span the range of image densities to be expected.
  • the subject of positive and reversal image development should be discussed.
  • the development of the image simulated on the sensing wheel I8 does not depend upon either a positive or reversal image.
  • the read head 20 in this embodiment performs an optical reading function, the systems should be arranged so that proper control of the toner particles is effective regardless of whether positive or reversal images are being used. Additional toner should he added to the mix when the concentration of toner on the developed portion of the wheel as sensed by the read head 20 falls below a predetermined minimum.
  • the simulated image on the sensing wheel, or toner pickup, 18 were to be established once and continually developed, toner particles would have an accumulative effect on the optical sensing. Therefore, in the case of the present invention, the simulated image (potential) is removed and re-established for each development. Regardless of the charge potentials established on the sensing wheel surfaces. the present invention periodically cycles the establishment and cancellation of the change pattern with rotation of the sensing wheel. This cycling of the charge pattern is effected, for example, by an electromechanical cam structure causing the simulated image to be altered, say three times for each revolution of the sensing wheel 18. In this way, the magnetic brush 14 appears to be developing a completely new image for each revolution of the sensing wheel 18.
  • the image potentials actually programed onto the sensing wheel 18 may be selectively changed in magnitude to provide a new toner concentration level.
  • the circuitry looks at the sensing wheel when it is clean as well as when toner is deposited. In this way,
  • the circuit corrects for slight changes in the strength of the signal from the optical read head due to contaminants or changes in the reflectivity of the wheel surfaces.
  • Sensing wheel 18 is driven by a motor, not illustrated, in a direction indicated by the arrow in FIG. 1.
  • the sensing wheel 18 is relatively short in axial length and, as such, makes contact with only a small axial portion of magnetic brush 14.
  • the sensing wheel 18 is constructed of a number of cylindrical discs 22, 23 and 24 of a material electrically conductive in nature. Insulating discs 26 are positioned at the common abutments of the conductive discs 22, 23 and 24.
  • the two outer electrically conductive discs 22 and 24 are electrically connected to a brush and slip ring 25 by internal wires, not illustrated.
  • inside disc 23 is connected to a second brush and slip ring indicated by the numeral 27.
  • one electrical potential is connected to the outside two conductive discs 22 and 24 and another electrical potential is connected to the inside conductive disc 23, causing a potential difference to exist across sensing wheel 18.
  • the sensing wheel is coated with semiconductor material in order to prevent direct shorting at the magnetic brush interface. Also, this effectively divides each of the discs into separate surface areas which substantially retains the charge impressed thereon while in contact with the magnetic brush. Thus, it is possible for a portion of sensor disc to have toner while another portion does not, to provide a series of toned and untoned areas around the disc which are seen by optical sensor 20, as hereinafter explained.
  • this electrical potential difference is used to simulate a charged image.
  • the potential difference established on the sensing wheel 18 simulates the conditions of the image and background area.
  • the values of the electrical potentials applied to the sensing wheel 18 correspond to specific image or background potentials.
  • the values of the voltages applied to the sensing wheel are arranged to cause the simulated image to appear initially on the center conductive disc 23. At the same time, the simulated background appears on the outside conductive discs 22 and 24.
  • Optical read head 20 is positioned to read only the center conductive disc 23 to perform its intended function.
  • a light source 30 is provided which directs light onto the surface area of center disc 23.
  • a light dispersing member 32 is included in the light path from light source 30, to assure that no light reflected from the walls of the path of light on the way to the sensing wheel 18 affects the sensing.
  • the light which is reflected from the surface of center disc 23, which may or may not have toner powder on it, is directed to a conventional photoresponsive device 36 through a dispersing member 34.
  • the purpose of the dispersing member 34 is to assure that the optical density is not affected by reflections from parts of the read head 20 itself.
  • any scheme which does not allow light to be reflected from the walls of the passage through which the light passes to and from the sensing wheel 18 serves the purpose intended.
  • the scheme used involves producing ordinary helical thread along the walls of the passage. The effect is to not allow any light impinging upon the inside surfaces of the passage to re-cnter the directed beam of light.
  • surfaces of the read head are dark in color in order that toner deposits upon the head not affect the reflectivity of light. It is also desirable to provide air currents in the vicinity of the read head which prevent toner powder from being deposited on read head 20.
  • the image is developed by toner deposited from the magnetic brush 14 as the sensing wheel rotates with the conductive disc 22, 23 and 24 surfaces in contact with the magnetic brush 14.
  • the read head 20 detects the optical density of the simulated image on conductive disc 23 by sensing the intensity of light reflected from the surface area of conductive disc 23. The larger the concentration of toner on this surface area, the lesser is the reflected light intensity.
  • the specular reflection of light, measured in density units, off of the deposited toner is inversely proportional to the mass of toner per unit are. This relationship may be expressed by the equation:
  • FIG. 3 is a block diagram of a typical electrical circuit used to detect and compare the developed simulated image.
  • the light responsive device in this case is a photo transistor 36 which is connected to a conventional logarithmic amplifier 38.
  • the logarithmic amplifier is used since the density unit change is directly proportional to the log of the ratio, current untoned to current toned as set forth in the above equation.
  • the output of this logarithmic amplifier 38 is then connected directly to an appropriate peak-to-peak detector 40, as are well known to those skilled in the electrical arts.
  • the function of the peak-to-peak detector 40 is to provide an output signal representative of the total change in optical density between the toned and untoned sensed on disc 23.
  • the output of the peak-to-peak detector 40 is fed to a conventional comparator 42, which compares the total change in optical density with the optical density of an ideal image. Finally, the output signal from the comparator 42 is connected to an appropriate control circuit 44 which activates a conventional dispenser when required.
  • a conventional dispenser Such toner dispensers are well known and it is not intended that such constitute a part of the present invention.
  • the image is programed onto the sensing wheel 18 by selectively adjusting a potentiometer associated with the power supply and program control 54.
  • This adjustment determines to a greater or lesser extent the attraction of toner to the sensing wheel and the amount which will be deposited per unit area if the toner concentration in the mix is ample.
  • the toner concentration falls below a minimum level, the amount of toner picked up by the wheel will likewise diminish to provide an appropriate signal from comparator 22 which causes toner to be added to the mix.
  • the sensing wheel since the potentials correspond to image and background areas, the sensing wheel accurately simulates the conditions of developing an actual copy.
  • the potential on center disc 23 is periodically reversed in polarity relative to the magnetic brush core. This reverses the direction of the net electrostatic field at the interface between the brush and the sensing wheel, whereby toner powder previously deposited on the sensing wheel is returned to the brush. In the preferred embodiment, this occurs three times for each revolution of the sensing wheel. Of course, a greater or lesser number of revolutions may be utilized, if desirable, to do so.
  • FIG. 4 a graph of the potential applied to the center disc 23 as a function of time and wheel position is illustrated in solid line.
  • the potential of the magnetic brush core is indicated by V,. and is maintained constant, as indicated by line 48.
  • V;,,, represents the image area potential, while V,,,, corresponds to the background potential.
  • the potential applied to center disc 23 is reversed three times per revolution of the sensing wheel. With V,-,,, impressed on center disc 23, as indicated at 50, toner is attracted from magnetic brush 14. After the sensing wheel has rotated one-third of a revolution, V is applied to sensor disc 23, as indicated at 52. This causes the positive toner particles to return to the magnetic brush in the area of the interface.
  • This potential remains on the center disc for the second third of the revolution, after which V is again applied to cause toner to be attracted to the wheel in the area of the interface with magnetic brush 14.
  • the time during which this potential is applied is indicated by the numeral 54 and continues until one wheel revolution has been completed as indicated at 7rD.
  • the center disc may be toned and cleaned more effectively if the potential applied to outer discs 22 and 24 are also changed as the potential on center disc 23 is cycled.
  • FIG. 5b provides alternate toning and cleaning of the outer discs out of phase with the cycling of center disc 23. It has been found that this aids migration of the toner particles away from the center disc during the cleaning operation.
  • a V potential is applied to the outer discs at the same time the cleaning potential (in this case V,,,,.) is applied to center disc 23.
  • the cleaning potential in this case V,,,,.
  • the outer electrodes, 22 and 24 may not be required and only electrode 23 would be used.
  • control 46 reverses the V,,,,- and V,-,,, potentials applied to the center and outer discs.
  • control 46 reverses the V,,,,,- and V,-,,, potentials applied to the center and outer discs.
  • the present invention provide a versatile toner concentration control including a sensing member which is programmable to simulate an actual latent image pattern. By adjusting the electrical potential applied to the sensing member, the background and image conditions may be selected. Furthermore, the sensing system automatically ajusts for changes in signal strength due to contaminants on the sensing member or changes in reflectivity over a period of time.
  • the background voltage V,,,,. is in the range of 25-50 volts above the brush core potential V,
  • the image potential V,-,, is approximately 150 volts below the brush core voltage.
  • the present invention be limited to the potential as such may be very dependent upon the paramaters of the overall system.
  • the invention be limited to the specific circuitry illustrated in FIG. 3, or to the specifically described sensing head illustrated in FIG. 2.
  • Various modifications of the circuitry may be made as will be obvious to those skilled in the art.
  • other types of sensing heads may be found to be appropriate for providing input signals to the system of the present invention.
  • a system for sensing the effective concentration of toner in the mix comprising:
  • toner pickup means for attracting the toner paticles from the developer mix handled by the developer unit and including a rotatably mounted pickup member separate from the latent image pattern and divided into at least first and second surface areas substantially insulated from each other,
  • program circuit means for applying a first electrical potential to said first area and a second electrical potential different than said first electrical potential to said second area, said first electric potential being of a polarity to attract the toner particles to said first area and corresponding to the imaged areas of the image pattern to be developed, said second electric potential corresponding to the background areas of the image pattern to be developed,
  • a system for sensing the effective concentration of toner in the mix comprising:
  • the member includes a third surface area electrically insulated from and axially adjacent to said first surface area, said first surface area being disposed intermediate said second and third surface areas, said program circuit means applying said second electrical potential corresponding to the background of the image pattern to said third toning area.
  • gram circuit means alternately applies said first and second potentials to said second area and to said third area.
  • tion apparatus having a developer unit for depositing toner onto a latent image pattern from a developer mix containing toner particles and carrier particles, a system for sensing the effective concentration of toner in the mix, said system comprising:
  • toner pickup means for attracting the toner particles from the developer mix handled by the developer unit and including a pickup member separate from the latent image pattern and divided into at least first and second surface areas substantially insu- 5 lated from each other,
  • program circuit means for applying a first electrical potential to said first area and a second electrical potential different than said first electrical potential to said second area, said first electric potential being of a polarity to attract the toner particles to said first area and corresponding to the imaged areas of the image pattern to be developed, said second electric potential corresponding to the background areas of the image pattern to be devell5 oped,
  • said pickup member comprising a rotatably mounted member associated with the developer unit, said first and second areas being axially disposed of each other.
  • program circuit means for applying a first electrical potential to said first area and a second electrical potential different than said first electrical potential to said second area, said first electric potential being of a polarity to attract the toner particles to said first area and corresponding to the imaged areas of the image pattern to be developed, said second electric potential corresponding to the background areas of the image pattern to be developed, a source of light, means for sensing the light reflected from said first area to provide a signal representative of the light intensity, and I control circuit means connected to said sensing means for providing a toner concentration signal representative of the effective difference between said clean and tone signals compared to a reference signal corresponding to an ideally developed image.
  • control circuit means includes logarithmic amplifier means receiving said tone and clean signals and peakto-peak detector means coupled to the output of said amplifier means for providing said toner concentration signal.
  • an electrophotographic reproduction apparatus having an insulation member for carrying a latent image pattern and a developer unit with means for applying toner to the image pattern from a mix of toner and carrier particles, a system for sensing the ability of the developer mix to supply sufficient toner for developing the image pattern at a satisfactory optical density level, said system comprising:
  • toner pickup means for attracting toner particles from said developer application means, said pickup means including a toner pickup member with a surface in operative engagement with said application means and independent of said insulation member for receiving said toner from said application means,
  • circuit means for alternately applying a toning electrical potential and a cleaning electrical potential to said pickup member surface area to attract and remove said toner, respectively,
  • sensing means for sensing the intensity of light reflected from said pickup member area both when said toning and cleaning electrical potentials are applied providing output signals which together are representative of concentration of deposited toner.
  • said pickup member surface comprises first and second areas substantially insulated from each other, said circuit means applying said toning and cleaning potentials to said first area and associated toning and second potentials corresponding to the image and background areas respectively of the latent image pattern.
  • said pickup member comprises a rotatably mounted member in operative engagement with said developer applicator means for receiving toner therefrom.
  • a system for sensing the concentration of toner in the mix comprising:
  • toner pickup means associated with the developer unit for attracting toner particles from the developer mix and including a rotatable pickup member having an outer surface area adapted to receive toner particles from the developer mix, program circuit means for successively applying tone and clean potentials to said pickup member, said tone potential causing attraction of toner onto said outer surface area and said clean potential causing repulsion of said toner from said outer surface area, a source of light irradiating said outer surface area, means for sensing the light reflected from said outer surface area with and without toner deposited thereon to provide tone and clean signals, respectively.
  • control circuit means connected to said sensing means for providing a toner concentration signal representative of the effective difference between said clean and tone signals compared to a reference signal corresponding to an ideally developed image.
  • control circuit means includes logarithmic amplifier means receiving said toner and clean signals and peakto-peak detector means coupled to the output of said amplifier means for providing said toner concentration signal.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Control Or Security For Electrophotography (AREA)
US421226A 1973-12-03 1973-12-03 Programmable toner concentration control Expired - Lifetime US3911861A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US421226A US3911861A (en) 1973-12-03 1973-12-03 Programmable toner concentration control
CA212,596A CA1034184A (fr) 1973-12-03 1974-10-29 Commande programmable de concentration en toner
GB48048/74A GB1483471A (en) 1973-12-03 1974-11-06 Electrostatic copying
GB3244/77A GB1483472A (en) 1973-12-03 1974-11-06 Electrostatic copying
DE19742456936 DE2456936A1 (de) 1973-12-03 1974-12-02 Vorrichtung zum feststellen der in einem entwicklergemisch wirksamen tonerkonzentration
FR7439536A FR2253233B1 (fr) 1973-12-03 1974-12-03

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US421226A US3911861A (en) 1973-12-03 1973-12-03 Programmable toner concentration control

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US3911861A true US3911861A (en) 1975-10-14

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CA (1) CA1034184A (fr)
DE (1) DE2456936A1 (fr)
FR (1) FR2253233B1 (fr)
GB (2) GB1483472A (fr)

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US4082445A (en) * 1975-11-21 1978-04-04 Xerox Corporation Toner control system for an electrostatic reproduction machine
US4178095A (en) * 1978-04-10 1979-12-11 International Business Machines Corporation Abnormally low reflectance photoconductor sensing system
US4179213A (en) * 1978-04-10 1979-12-18 International Business Machines Corporation Vector pinning in an electrophotographic machine
US4183657A (en) * 1978-04-10 1980-01-15 International Business Machines Corporation Dynamic reference for an image quality control system
US4236486A (en) * 1978-03-27 1980-12-02 Tokyo Shibaura Denki Kabushiki Kaisha Toner concentration control device
US4357901A (en) * 1981-09-03 1982-11-09 Bunnington Corporation Method and system for magnetically sensing and controlling toner concentration and optical density of copies in electrostatic reproduction
US4372672A (en) * 1980-12-22 1983-02-08 International Business Machines Corporation Self-triggering quality control sensor
WO1992011585A1 (fr) * 1990-12-24 1992-07-09 Eastman Kodak Company Dispositif de controle du melange de developpateur destine a des unites de developpement couleur
US5148217A (en) * 1991-06-24 1992-09-15 Eastman Kodak Company Electrostatographic copier/printer densitometer insensitive to power supply variations
US20200026218A1 (en) * 2018-07-19 2020-01-23 Canon Kabushiki Kaisha Sensor unit and image forming apparatus

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Publication number Priority date Publication date Assignee Title
JPS5842073A (ja) * 1981-09-08 1983-03-11 Fuji Xerox Co Ltd 現像剤の濃度制御装置

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US3682132A (en) * 1969-03-03 1972-08-08 Xerox Corp Automatic developer controller
US3756192A (en) * 1971-12-17 1973-09-04 Ibm Automatic toner concentration control system
US3791744A (en) * 1972-02-22 1974-02-12 Dyk Res Corp Van Xerographic toner concentration measuring apparatus and method
US3801196A (en) * 1973-04-20 1974-04-02 Xerox Corp Toner concentration regulating apparatus
US3818864A (en) * 1971-09-14 1974-06-25 Xerox Corp Image developing apparatus

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US3580673A (en) * 1968-08-26 1971-05-25 Xerox Corp Cleaning apparatus
US3682132A (en) * 1969-03-03 1972-08-08 Xerox Corp Automatic developer controller
US3818864A (en) * 1971-09-14 1974-06-25 Xerox Corp Image developing apparatus
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US4236486A (en) * 1978-03-27 1980-12-02 Tokyo Shibaura Denki Kabushiki Kaisha Toner concentration control device
US4178095A (en) * 1978-04-10 1979-12-11 International Business Machines Corporation Abnormally low reflectance photoconductor sensing system
US4179213A (en) * 1978-04-10 1979-12-18 International Business Machines Corporation Vector pinning in an electrophotographic machine
US4183657A (en) * 1978-04-10 1980-01-15 International Business Machines Corporation Dynamic reference for an image quality control system
US4372672A (en) * 1980-12-22 1983-02-08 International Business Machines Corporation Self-triggering quality control sensor
US4357901A (en) * 1981-09-03 1982-11-09 Bunnington Corporation Method and system for magnetically sensing and controlling toner concentration and optical density of copies in electrostatic reproduction
WO1992011585A1 (fr) * 1990-12-24 1992-07-09 Eastman Kodak Company Dispositif de controle du melange de developpateur destine a des unites de developpement couleur
US5148217A (en) * 1991-06-24 1992-09-15 Eastman Kodak Company Electrostatographic copier/printer densitometer insensitive to power supply variations
US20200026218A1 (en) * 2018-07-19 2020-01-23 Canon Kabushiki Kaisha Sensor unit and image forming apparatus
US10890860B2 (en) * 2018-07-19 2021-01-12 Canon Kabushiki Kaisha Sensor unit and image forming apparatus

Also Published As

Publication number Publication date
GB1483472A (en) 1977-08-17
FR2253233A1 (fr) 1975-06-27
GB1483471A (en) 1977-08-17
CA1034184A (fr) 1978-07-04
FR2253233B1 (fr) 1978-09-15
DE2456936A1 (de) 1975-06-05

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