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WO1997022039A1 - Dispositif et procede electrophotographique - Google Patents

Dispositif et procede electrophotographique Download PDF

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Publication number
WO1997022039A1
WO1997022039A1 PCT/GB1996/003045 GB9603045W WO9722039A1 WO 1997022039 A1 WO1997022039 A1 WO 1997022039A1 GB 9603045 W GB9603045 W GB 9603045W WO 9722039 A1 WO9722039 A1 WO 9722039A1
Authority
WO
WIPO (PCT)
Prior art keywords
colour
image
printing
consumption
electrophotographic apparatus
Prior art date
Application number
PCT/GB1996/003045
Other languages
English (en)
Inventor
Geoffrey Fermor-Dunman
Original Assignee
Gestetner Management Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gestetner Management Limited filed Critical Gestetner Management Limited
Priority to AU11038/97A priority Critical patent/AU1103897A/en
Publication of WO1997022039A1 publication Critical patent/WO1997022039A1/fr

Links

Classifications

    • 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
    • G03G15/0126—Details of unit using a solid developer
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/23—Reproducing arrangements
    • H04N1/29—Reproducing arrangements involving production of an electrostatic intermediate picture
    • H04N1/295—Circuits or arrangements for the control thereof, e.g. using a programmed control device, according to a measured quantity
    • 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
    • G03G15/55—Self-diagnostics; Malfunction or lifetime display
    • G03G15/553—Monitoring or warning means for exhaustion or lifetime end of consumables, e.g. indication of insufficient copy sheet quantity for a job
    • G03G15/556—Monitoring or warning means for exhaustion or lifetime end of consumables, e.g. indication of insufficient copy sheet quantity for a job for toner consumption, e.g. pixel counting, toner coverage detection or toner density measurement

Definitions

  • the present invention relates to an electrophotographic apparatus and to an electrophotographic method in which the copy cost can be more accurately determined than with conventional machines.
  • the copy cost of an electrophotographic apparatus has been estimated on the basis of an average image density on the sheet (usually less than 15%) , bearing in mind that the typical sheet being copied is a sheet of text which has generous margin areas and which in any case consists of relatively small dark areas on an extensive white background where no toner will be needed.
  • the copy cost is usually a composite of the material costs (toner and other consumables such as the photoconductive member of the copier) , and a second part which i ⁇ a function of the maintenance costs and other overhead charges.
  • the component of the charge to cover the toner usage is normally pitched at a high enough level so that the toner consumption will never outstrip the allowance made for it in the copy cost calculation. This may result in the user of electrophotographic apparatus paying a lot more for the copies than would otherwise be necessary on the basis of material costs.
  • US-A-4969011, TJS-A-4974024, US-A-5075726 and US- A-5124751 disclose such machines. It is also known to provide such apparatus with means to warn the operator that toner needs to be added in order to maintain copy quality. US-A-5202769 and GB-A-2259583 disclose such machines.
  • one aspect of the present invention provides electrophotographic apparatus comprising means for scanning an original image; printing means effective to apply onto a carrier a pattern of toner, said printing means being controlled in response to said scanning means; means for evaluating the consumption of colouring medium used by said printing means; and means for delivering to the exterior of said electrophotographic apparatus a measure, relevant to a given period, of the consumption of said colouring medium.
  • the copy cost calculating means are located at a station remote from the consumption evaluating means so that the individual electrophotographic apparatus only needs additional means to generate a signal of toner consumption.
  • the calculating means can then be common to various electro ⁇ photographic apparatus units in the field. More preferably the signals are representative of the consumption of all three, or optionally four, toners in a colour copying process.
  • a second aspect of the present invention provides an electrophotographic process comprising scanning a multi ⁇ colour image on an original; applying a plurality of process colour images to a carrier in response to said scanning means to build up a multi-colour image on said carrier; measuring the consumption of the colouring medium of the respective process colours; and assessing the material costs of said electrophotographic process.
  • Fig. ZI shows a first embodiment of an analog color photocopier in accordance with the present invention
  • Fig. 2 shows a modification of the photocopier of Fig. 1;
  • Fig. 3 hows a digital colour copier in accordance with the invention.
  • Figure 1 shows a first embodiment of analog photocopier in which light pas ⁇ es along an optical path between a lamp on a moving scanning sledge and a moving photoconductor, by way of a lens, to expose the photoconductor image-wise to an image similar to that on the original sheet on a stationary transparent platen 1 above the path of the scanning sledge.
  • the scanning sledge carries a first mirror 2 which deflects light from the scanning lamp 3 on to an upper compensating mirror 4 which then reflects it on to a lower compensating mirror 5 from which the light passes back across the machine, below the platen 1, through a lens 6 which ensures that the beam, after having been reflected by a stationary mirror 7, i ⁇ focused on the surface of the photoconductor drum 8.
  • the upper and lower compensating mirrors 4 and 5 are carried on a sledge which traverses at one half of the traverse speed of the scanning sledge (and hence along a path only half as long as that of the scanning sledge) , thereby ensuring that the light path from the scanned point on the surface of the original 10 on the platen to the stationary line of incidence on the photoconductor drum 8 (which is itself rotating so that the image effectively traverses along the surface of the drum in a circumferential direction) remains constant.
  • the fixed focus lens 6 will be repositioned so that the scanned line of image will be in a given magnification or reduction ratio a relative to the original image line and the ratio of the linear speed of the surface of photoconductor drum 8 relative to that of the scanning ⁇ ledge will be reduced or increased accordingly from 1:1 to equal the value of ratio a .
  • Copy sheets 11 from a copy sheet feed tray 12 are fed one at a time into contact with the surface of a copy carrier drum 13 to which the copy sheet 11 becomes attracted by suction applied within the copy carrier drum 13. This ensure ⁇ that the registration of the sheet 11 remains constant on the surface of the copy carrier drum 13 but more importantly there is also a sheet stop to en ⁇ ure that the registration i ⁇ accurate in relation to the position of the scanning ⁇ ledge.
  • the copy sheet has acquired its multi-colour image it is released from the surface of the copy carrier drum 13 and passes onwardly to a pressure fuser 14 by way of a feed conveyor belt 15, and the finished copy sheet together with its fused multi-colour image thereon is then delivered to a collecting tray 16.
  • a pre-clean corona 19 a cleaning brush 20, a charging corona 21, a black toner developer unit 22, and the three process colour developer units 23, 24 and 25 for the three process colours (cyan, magenta, and yellow) .
  • process colour is intended to denote the appropriate one of the colours cyan, magenta and yellow, whereas the black toner is always referred to as such.
  • the four developer units 22 to 25 have respective output lines 22a, 23a, 24a and 25a, applying signals to a processing unit 26 which then delivers four outputs to toner counters 22b, 23b, 24b and 25b.
  • the signal ⁇ for the toner counters may be derived from the respective developer unit, to record the quantity of toner delivered to that developer or from the developer control unit which determines how long each developer unit remains active during a particular copy cycle, or any other convenient parameter.
  • the proces ⁇ or 26 may also have inputs to respond to the pre-exposure charging voltage at charging corona 21, or inputs from ⁇ ensor ⁇ responsive to ambient conditions which will control the efficiency of toner transfer.
  • a rotating cruciform cross-section optical filter 17 is positioned in the light path between the final mirror 7 and the surface of the photoconductor drum 8 and can be indexed to bring an appropriate one of its four filter paddles into that light path.
  • a first filter paddle for example the red filter
  • a first filter paddle is positioned in the light path BO that only red light will be able to pass through the filter and to form on the photoconductor drum a negative image corresponding to the cyan process colour needed in the first developer cycle.
  • the first cycle of the photoconductor drum 8 passes its surface successive ⁇ ively past the pre-clean corona 19, the cleaning brush 20 and the charging corona 21 so that the surface arriving at the line of incidence with the scanned beam is uniformly non-conduc ⁇ tive and thereby still charged with the charge imparted by the charging corona 21.
  • those parts which are exposed to light will become conductive and will allow the surface charge to dissipate through the photoconductor to an electroconductive metal carrier drum on which the photoconductive material is deposited, whereas those parts which are not expo ⁇ ed to the scanned light beam will remain non-conductive and therefore still charged with the charge imposed by the charging corona 21.
  • the thus image-wise exposed photoconductor surface passes onwardly past the four developer units 22 to 25, of which only the cyan developer unit 23 will be active and will develop the image.
  • the surface of the photoconductor drum 8 then continues past the pre-clean corona 19, the cleaning brush 20, and the charging corona 21.
  • the filter 17 will have indexed to bring the green filter paddle into the path of the scanning beam and hence the latent electrostatic image formed on the surface of the photoconductor drum 8 will be different and will correspond to the magenta copy image which will now be developed by activation of the developer unit 24 with the other developer units 22, 23 and 25 inactive.
  • This cycle proceeds as for the cyan development and the third and subsequent cycle then proceeds with the blue filter paddle in the path of the scanning beam and the yellow developer unit 25 operative with the other three developer unite 22, 23 and 24 inoperative.
  • the fourth paddle of the filter 17 i ⁇ clear and will allow a white scanning beam to pass unfiltered to the line of incidence on the photoconductor drum 8, at which time the elements 19 to 21 will be operating as before but this time the black developer unit 22 will be operating while the cyan, magenta and yellow developer units 23, 24 and 25 are inoperative. Again the appropriate signal is sent down the line 22a to the processor 26 which generates a toner consumed signal for the counter 22b.
  • FIG 2 shows an alternative form of the photocopier of Figure 1, where the differences reside in the processing of the toner consumption signal.
  • the various optical and electrostatic elements, as well as the paper handling elements, need not be described again.
  • the monitoring can be either continuous or by periodic interrogation of the respective photocopiers from the central remote processor 30.
  • Figure 3 illustrates in schematic form one embodiment of a digital photocopier.
  • the original 50 on a transparent platen 51 i ⁇ scanned by a ⁇ canning ⁇ ledge comprising a light source 52 and a first mirror 53 which deflects the scanned beam horizontally towards an upper compensating mirror 54 which then passes the beam downwardly to a lower compensating mirror 55.
  • the upper and lower compensating mirrors are themselves traversed at a constant speed which is half the constant ⁇ canning speed of the scanning sledge carrying the light source 52 and first mirror 53.
  • the optical path again includes a lens 56 but the focused beam from the lens is received on a CCD (charge coupled device) 57 from which the electrical output indica- tive of the scanned beam passes along line 58 to a processor
  • CCD charge coupled device
  • the CCD 57 includes pixels responsive to each of the three primary colours and effectively scans a complete line of the original simultaneously.
  • the traversing of the scanning sledge ensures that the entire original area on the platen is scanned line by line.
  • the processor 59 receives electrical signals corresponding to the complete image.
  • magnification and reduction the ratio of scanning sledge linear speed to the linear speed common to the photoconductor drum 62 and the carrier belt 67 will be variable but magnification or reduction of the scanned line will be effected electronically by expansion or compression of the image line.
  • the outputs from the processor 59 comprise a first output 60 which drives the print head 61 to expose the photoconductor drum 62 with images of the respective colours.
  • the black toner developer unit 63 is energised by output line 63a from the processor 59, and likewise the cyan, magenta and yellow developer units 64, 65 and 66 are energised by lines 64a, 65a and 66a, respectively.
  • the sequence of cleaning, charging, exposure and developing of the surface of the photoconductor drum 62 is the same as for the Figure 1 embodiment, but in this case each of the images is immediately transferred to an endless carrier belt 67 which cycles freely for four (or optionally only three) revolutions of the photoconductor drum 62 to acquire the three separate process colour image components and the optional black component to combine to provide the final colour image. Then only after acquisition of the last (usually the fourth) image component, the yellow image component, does the transfer station 68 operate to transfer the multi-colour i age from the carrier belt 67 to a copy sheet 69 being fed from a copy sheet supply tray 70 to a copy sheet collection tray 71 by way of the image transfer station 68, a copy sheet conveyor belt 72, and a fuser station 73.
  • the black toner developer unit 63 can be used, if desired, for mono ⁇ chrome copying.
  • the sequence of printing the process colours is cyan-magenta-yellow (after the optional black first toner) .
  • Such four component operation allows the four developer units 63, 64, 65 and 66 to build up the required image, but with an overall economy of toner used.
  • Such four component operation is normal in digital copiers. Where only a proportion of the common image component is substituted by black toner, the proportion may be adjustable by the user of the copier.
  • the processor 59 delivers further "toner consumption” outputs on lines 63b, 64b, 65b and 66b, equivalent to the consumption of toner for each of the four developer units 63, 64, 65 and 66, respectively.
  • Those ⁇ ignal ⁇ are passed by telemetry lines 63b to 66b on to a remote toner consumption monitoring station 74, equivalent to the remote monitoring station 30 of Figure 2.
  • the multi-colour image can be built-up directly on the copy sheet, much in the manner described above with reference to Figures 1 and 2, rather than being transferred from the photoconductor drum first to the carrier belt 67 and then to the copy ⁇ heet.
  • a multi-colour photocopier is usually reserved for pictorial images with solid outline where the consumption of toner i ⁇ much higher, and furthermore the toner itself may be more costly.
  • the optional black toner and the individual toners used for the three process colour developers may differ in cost and thus the total material cost of running such a multi-colour photocopier may depend greatly upon the nature of the work of a particular user.
  • the image area of a colour photocopy may be in excess of 80% of the total sheet area (compared with a typical figure of the order 15% for a monochrome photocopier copying typescript) ; also this image is made up of three or four separate toners which in many parts of the image all of the printed components will be ⁇ uperimposed on one another with the result that the total quantity of toner used for a multi ⁇ colour image may be equivalent to a lot more than 100% of the sheet area.
  • Becau ⁇ e of this higher actual toner consumption it i ⁇ u ⁇ eful to know the consumption of toner rather than simply assuming an average consumption becau ⁇ e it will vary so much between one user and another, and it is also useful to know the make up of that total in terms of the three process colour toners (Cyan, Magenta and Yellow) , and optionally the black fourth toner, used in the copy.
  • the three process colour toner counters 23b, 24b and 25b and the optional black toner counter 22b Fig.
  • the counters 22b, 23b, 24b and 25b therefore have a display which can be read by the user, and checked by the engineer on any service calls.
  • the lines to the toner counters 22b, 23b, 24b and 25b may be replaced by a single line by which the signals to the toner counters can be multiplexed.
  • the term electrophotographic process has been used to denote a process which uses an electric drive means to generate the image.
  • the electric drive means may comprise an electrostatic charge device for charging a photoconductor while in its non-conductive state so a ⁇ to allow select discharging of the photoconductor when it becomes selectively photoeonductive in an image-wise manner after exposure to an optical scanning system.
  • the electric driver may comprise an electric print head respon ⁇ sive to input signals derived from an electric image scanning array.
  • Other electrophotographic mechanisms may be used in conjunction with the toner consumption-measuring concept of the present invention.
  • the toner consumption signal may be taken from any convenient part of the apparatus.
  • the signal may be derived from the scanning signal (for example the output of the CCD 57 in Figure 3) .
  • the toner consumption output may be taken from the processor unit 59 or equivalent in a digital photocopier.
  • the toner consump ⁇ tion signal may be derived from the control line to the developer units. As indicated above this may involve taking the developer unit "on" time a ⁇ a measure of the toner consumption. Otherwise it is possible for the toner density of the image to be analysed optically, for example by printing a calibration patch on the photoconductor, or on the carrier 67 of Figure 3 and observing the quantities of the toners (the three proce ⁇ B colour ⁇ and the optional black) used to make up that image.
  • the important requirement is that there should be a measure of the toners used, and that this should be inte ⁇ grated over an extensive number of copies to indicate the average content of toner consumed.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Color Electrophotography (AREA)

Abstract

Un photocopieur comporte des organes de lecture optique (2-8; 12) réagissant aux couleurs primaires d'une plaque porte feuille (1) et des organes d'impression (23-25) permettant de traiter les couleurs complémentaires des couleurs primaires correspondants desdits organes de lecture optique et permettant d'appliquer sur un support (8) de façon à y définir une image polychrome, une matière colorante telle que de la poudre d'impression pour chacune des couleurs de traitement considérées. Un processeur (26) génère à chacun des compteurs (23a, 24a et 25a) des signaux caractéristiques de la consommation des différentes matières colorantes de traitement ou des différentes poudres d'impression. Ce procédé ainsi que ce dispositif conviennent aussi bien à un photocopieur numérique qu'à un photocopieur analogique.
PCT/GB1996/003045 1995-12-11 1996-12-10 Dispositif et procede electrophotographique WO1997022039A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU11038/97A AU1103897A (en) 1995-12-11 1996-12-10 Electrophotographic apparatus and method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9525294.6 1995-12-11
GB9525294A GB2308096A (en) 1995-12-11 1995-12-11 Electrophotographic apparatus

Publications (1)

Publication Number Publication Date
WO1997022039A1 true WO1997022039A1 (fr) 1997-06-19

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ID=10785244

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/003045 WO1997022039A1 (fr) 1995-12-11 1996-12-10 Dispositif et procede electrophotographique

Country Status (3)

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AU (1) AU1103897A (fr)
GB (1) GB2308096A (fr)
WO (1) WO1997022039A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62280961A (ja) * 1986-05-30 1987-12-05 Canon Inc 管理システム
US4897697A (en) * 1987-07-03 1990-01-30 Minolta Camera Kabushiki Kaisha Counting system for use in a copying machine
US5202769A (en) * 1990-12-10 1993-04-13 Fuji Xerox Co., Ltd. Digital electrostatic printing apparatus using a counted number of pixels of various densities to determine and control an amount of toner used during image development
US5305199A (en) * 1992-10-28 1994-04-19 Xerox Corporation Consumable supplies monitoring/ordering system for reprographic equipment
US5383129A (en) * 1993-08-31 1995-01-17 Xerox Corporation Method of estimating cost of printing materials used to print a job on a printing apparatus
DE19548907A1 (de) * 1994-12-27 1996-07-11 Toshiba Kawasaki Kk Bilderzeugungsgerät

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4969011A (en) * 1989-04-27 1990-11-06 Xerox Corporation Toner control system for xerographic reproduction machine
US4974024A (en) * 1989-07-03 1990-11-27 Xerox Corporation Predictive toner dispenser controller
US5075726A (en) * 1989-07-28 1991-12-24 Konica Corporation Toner density control device with adjustable reference values for multiple developer copier
JP3018395B2 (ja) * 1990-05-15 2000-03-13 ミノルタ株式会社 画像形成装置のトナー濃度制御装置
GB2259583B (en) * 1991-09-11 1995-08-16 Xerox Corp Toner monitoring in an electrostatographic printing/digital copying machine

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62280961A (ja) * 1986-05-30 1987-12-05 Canon Inc 管理システム
US4897697A (en) * 1987-07-03 1990-01-30 Minolta Camera Kabushiki Kaisha Counting system for use in a copying machine
US5202769A (en) * 1990-12-10 1993-04-13 Fuji Xerox Co., Ltd. Digital electrostatic printing apparatus using a counted number of pixels of various densities to determine and control an amount of toner used during image development
US5305199A (en) * 1992-10-28 1994-04-19 Xerox Corporation Consumable supplies monitoring/ordering system for reprographic equipment
US5383129A (en) * 1993-08-31 1995-01-17 Xerox Corporation Method of estimating cost of printing materials used to print a job on a printing apparatus
DE19548907A1 (de) * 1994-12-27 1996-07-11 Toshiba Kawasaki Kk Bilderzeugungsgerät

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ANONYMOUS: "Reproduction Facility Having a Number of Reproduction Devices", IBM TECHNICAL DISCLOSURE BULLETIN, vol. 31, no. 5, October 1988 (1988-10-01), NEW YORK, US, pages 211 - 213, XP002027635 *
PATENT ABSTRACTS OF JAPAN vol. 012, no. 170 (P - 705) 20 May 1988 (1988-05-20) *

Also Published As

Publication number Publication date
AU1103897A (en) 1997-07-03
GB9525294D0 (en) 1996-02-07
GB2308096A (en) 1997-06-18

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