EP0004573B1 - Xerographisches Kopiergerät - Google Patents

Xerographisches Kopiergerät Download PDF

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Publication number
EP0004573B1
EP0004573B1 EP19790100715 EP79100715A EP0004573B1 EP 0004573 B1 EP0004573 B1 EP 0004573B1 EP 19790100715 EP19790100715 EP 19790100715 EP 79100715 A EP79100715 A EP 79100715A EP 0004573 B1 EP0004573 B1 EP 0004573B1
Authority
EP
European Patent Office
Prior art keywords
toner
xerographic copier
area
test
photoconductor
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
Application number
EP19790100715
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English (en)
French (fr)
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EP0004573A1 (de
Inventor
Clement Card Wilson
George William Van Cleave
Larry Mason Ernst
Steven David Seigal
James Robert Champion
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
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International Business Machines Corp
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Publication date
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Priority claimed from US05/894,955 external-priority patent/US4183657A/en
Priority claimed from US05/894,957 external-priority patent/US4178095A/en
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0004573A1 publication Critical patent/EP0004573A1/de
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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
    • G03G15/50—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control
    • G03G15/5033—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control by measuring the photoconductor characteristics, e.g. temperature, or the characteristics of an image on the photoconductor
    • G03G15/5041—Detecting a toner image, e.g. density, toner coverage, using a test patch
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00025—Machine control, e.g. regulating different parts of the machine
    • G03G2215/00029—Image density detection
    • G03G2215/00033—Image density detection on recording member
    • G03G2215/00037—Toner image detection
    • G03G2215/00042—Optical detection

Definitions

  • This invention relates to xerographic machines.
  • a common type of developer mix currently in use in such machines is comprised of a carrier material, such as a magnetic bead, coated with a coloured powdery substance called toner. It is the toner which is attracted to the charged, latent image to develop that image and it is the toner which is then transferred from the latent image to the copy paper (where the copy paper is separate from the photoreceptive material). Finally, it is the toner which is then fused to the copy paper to produce the finished copy.
  • toner is a supply item which must be periodically replenished in the developer mix since the toner is carried out of the machine on the copy paper as a reproduced image. It is also apparent that the concentration of toner particles in the developer mix is significant to good development of the latent image since too light a toner concentration will result in too light a developed image and too heavy a toner concentration will result in too dark a developed image.
  • U.S. Patents 2,956,487 and 3,348,522 disclose the prior art.
  • U.S. Patent 2,956,487 provides a toner concentration control system where the reflectivity of the document image to be reproduced is used as a measure of toner density. This system appears subject to difficulty since reflectivity readings will change dependent upon the quality of the original.
  • U.S. Patent 3,348,522 discloses a toner concentration control scheme in which a special test image is developed outside the image area used for reproducing document copies.
  • U.S. Patent 3,926,338 discloses a circuit for use in a toner concentration control scheme.
  • thermally insensitive photodetectors must be used since the large amount of heat generated during machine operation affects the accuracy of toner concentration control readings.
  • this patent says that a stable amplifying circuit, stable referring to temperature stability, must be used in order to avoid destruction of the validity of the sensed signal.
  • U.S. Patent 4,082,445 shows another toner concentration control system in a copier machine.
  • a test stripe is produced adjacent each developed image of an original.
  • This stripe is produced by momentarily extinguishing an inter-image erase lamp which normally discharges the photoconductor between image areas thereon.
  • the density of the stripe is sensed and compared with that of the adjacent fully exposed areas to determine whether or not toner replenishment in the developer system is required.
  • each stripe is produced in an area of the photoconductor outside that normally occupied by an image .of an original. It has now been found that advantages accrue from providing a test area on the photoconductor within the area normally occupied by an image of an original.
  • the present invention provides a xerographic copier including means for producing on a re-usable photoconductive imaging surface a substantially uniformly toned test area bordered by a substantially untoned area, sensing means for sensing the optical density of said areas to produce first and second sensor signals representing respectively the density of said untoned and toned areas, and control means responsive to said first and second sensor signals to provide output signals whenever said first and second sensor signals differ by more than a predetermined amount, characterised in that said test area and bordering untoned area are positioned within a portion of the imaging surface upon which images of original documents are formed.
  • published European Patent Application No. 0 004 572 relates to a xerographic copier similar to the one described herein but employing a different control arrangement.
  • an image of a document to be copied is transferred to the photoconductive surface 26 through an optics module 25 producing that image on the photoconductive surface 26 at exposure station 27.
  • developer 23 develops the image which is then transferred to the copy paper.
  • preclean corona 22 and erase lamp 24 which discharge all of the remaining charged areas on the photoconductor.
  • the photoconductor continues to pass around and through the developing station 23 (which is also a cleaning station in this embodiment) until it reaches the charge corona 21 where the photoconductor 26 is again charged prior to receiving another image at exposure station 27.
  • FIGURE 2 is a perspective view of the optics system showing the document glass 50 upon which a document to be copied is placed.
  • An illumination lamp 40 is housed in a reflector 41.
  • Sample light rays 42 and 43 emanate from lamp 40 and are directed from dichroic mirror 44 to the document glass 50 whereat a line of light 45 is produced.
  • Sample light rays 42 and 43 are reflected from the document placed on the document glass to reflective surface 46; from there to reflective surface 47 to reflective surface 48 and thence through lens 9 to another reflective surface 49. From mirror 49 the light rays are finally reflected through opening 51 in wall 52 to reach photoconductor 26 whereat a line of light 45' is produced.
  • FIGURE 3 shows the various elements in the paper path in perspective.
  • a copy sheet 31 is shown with its trailing edge 31 A in the paper path at guides 12.
  • the copy paper is receiving an image at transfer station 13A and is in the process of having that image fused to itself by fuser rolls 1 5 and 16.
  • the leading edge 31 B of the copy paper is about to leave the document copier and proceed into the collator 19 which is represented in simplified form.
  • the photoconductor 26 continues to rotate until it comes under the influence of preclean corona 22 which applies a charge to the photoconductive surface to neutralize the remaining charge thereon.
  • Photoconductor 26 continues to rotate until the photoconductor comes under the influence of an erase light 24' in housing 24.
  • the erase light produces illumination across the entirety of the photoconductor 26 in order to complete the discharge of any remaining areas on the photoconductive surface which have not been neutralized by the preclean corona 22.
  • the photoconductor continues through the cleaning station of developer/cleaner 23, wherein any remaining toner powder not transferred to copy paper is cleaned from the photoconductor prior to the beginning of the next copy cycle.
  • the charge corona 21 lays down a uniform charge across photoconductor 26 which charge is variably removed when the image of the document is placed on the photoconductor at the exposure station 27 shown in FIGURE 1.
  • Preclean corona 32 and erase lamp 24' are off during this cycle.
  • replenisher 35 When the toner concentration control cycle is run, and if the result indicates a need to add toner to the developer, a signal is sent to replenisher 35 which holds a supply of toner and operates to dump a measured amount into the developer. In that manner, the toner density of the developer mix is replenished.
  • Any suitable replenisher mechanism may be used including the replenisher described in IBM Technical Disclosure Bulletin, Vol. 17, No. 12, pp. 3516, 3517.
  • FIGURE 3 shows a housing 32 containing the toner concentration control sensing system shown in FIGURES 4 and 6.
  • the photoconductor When it is desired to sense for the concentration of toner in the developer mix the photoconductor is charged as usual at the charge corona 21, but no image is placed on the charged photoconductor at exposure station 27. Instead, on this cycle, the erase lamp 24' remains on, discharging all of the charge which has been laid down by charge corona 21 in order to provide bare photoconductor for a reference test area. However, the erase lamp 24' is momentarily interrupted to produce a charged stripe toned sample for a test area.
  • the lamp 24' is comprised of an array of light-emitting diodes, the array can be segmented such that only a few of the LEDs are momentarily turned off and therefore only a small "patch” of charge remains on the photoconductor at the conclusion of this part of the cycle. If a fluorescent tube is used as the erase lamp 24', momentarily reducing its energization to a low level will produce a "stripe" of charge remaining on the photoconductor at the conclusion of this part of the cycle.
  • the charged test area continues to rotate in the direction A until it reaches the developer 23 where toner is placed onto the charged area to produce a toned sample test area.
  • a light-emitting diode (LED) or other suitable light source 33 is energized to produce light rays which reflect off the toned sample test area 35 and are reflected to a photosensor 34.
  • LED light-emitting diode
  • FIGURE 5 shows the layout of the photoconductor 26 with an image area 28 outlined therein.
  • a developed patch 30 has been produced within the image area 28.
  • FIGURE 2 shows apparatus for producing patch 30.
  • erase lamp 24' (see FIGURE 3) is momentarily interrupted to produce a stripe of charge.
  • 45' as a line of light producing an image on photoconductor 26
  • the line or stripe 45' is used to designate a stripe of charge produced by momentarily interrupting lamp 24'.
  • document lamp 40 is turned on during the test cycle so that light from lamp 40 will erase the stripe of charge 45' unless it is interrupted.
  • shutter 36 which is shown in FIGURE 2 as dropping across the slot 51 in wall 52.
  • Shutter 36 is actuated by solenoid 38.
  • light from lamp 40 is blocked away from photoconductor 26 by shutter 36, thus producing a stripe of charge 37.
  • erase lamp 24' will erase all of stripe 37 except for patch 30. In that manner, a patch instead of a stripe can be produced.
  • slot 51 should be positioned close to the photoconductive surface 26.
  • FIGURE 7 shows the layout of photoconductor 26 illustrating a technique for avoiding the need for skipping copies even when operating a long, multi-copy run. If the machine has the capability of producing two different size copies, for example, 216 x 280 mm. and 216 x 355 mm. The 45 mm part of the image area 28 can be used for the density test without skipping a copy.
  • FIGURE 7 shows the timing considerations needed for the erase lamp, the document lamp, and the shutter 36 of FIGURE 2.
  • the production of the test area is obtained by turning off the document lamp at the conclusion of viewing the 280 mm document and momentarily interrupting the erase lamp as shown on FIGURE 7. Of course, no shutter is used in that case.
  • the logic control of the machine provides a signal to trigger the viewing of a reference sample. This is accomplished by energizing LED 33 in the following manner.
  • the logic signal results in triggering a transistor switch (not shown) which connects the reference sample input line 60 to ground.
  • a transistor switch (not shown) which connects the reference sample input line 60 to ground.
  • the voltage on the negative input of OP AMP 61 is dropped from approximately 8 volts to about ground potential. This causes the negative input of OP AMP 61 to switch from a value higher than the positive input to one that is lower resulting in an inversion of OP AMP output from low to high on line 62.
  • That output is then fed back to the positive input to lock the OP AMP 61 in a high output condition avoiding oscillations.
  • the output voltage on line 62 is applied to transistor Q2 to turn that transistor on, thus closing a circuit from the 24-volt source through the light-emitting diode 33 and transistor Q2 to ground. The result is to provide light from the LED 33 to the photocell 34 at the precise time in the machine cycle to reflect light rays from the bare photoconductor to photocell 34.
  • a logic signal is provided to turn on a transistor switch, not shown, to connect the toned sample input line to ground. This results in lowering the negative input on OP AMP 63 from approximately 8 volts to ground potential and causes the output on line 64 to go high.
  • the signal on line 64 turns on the transistor Q1, causing the light-emitting diode to conduct through the transistor Q1 to ground.
  • the resistance levels connected with the transistor 01 are significantly lower than the resistances associated with transistor Q2.
  • the current level through transistor Q1 is significantly higher than the current level through Q2, thus creating a more intense light from LED 33 when the toned sample is viewed.
  • the bare photoconductor will reflect a higher light level than the toned photoconductor. It was recognized that the reflected light intensities exciting the photocell must be kept at a nearly equal level whether viewing a bare sample or a toned sample. The reason for this is to avoid the non-linearities which occur in photocell excitations from reception of different light levels to avoid the non-linearities in circuit response and to guarantee high signal levels whether viewing the bright reference sample or the dark toned sample in order to improve noise immunity. In a system which is designed to be relatively free from variations in component sensitivities, this is an important feature.
  • OP AMP 65 is connected as a transconductance amplifier. With photocell 34 off only a small dark current flow exists between the output of OP AMP 65 and the negative input. However, when the photocell is excited, the current flow is substantially increased causing a significant voltage drop across resistors R16 and R17 creating a voltage level at line 66 of perhaps 1 or 2 volts. Zener diode 67 limits the voltage level which can occur at line 66 to 8.5 volts, i.e., a swing of 8.5 volts from the photocell unexcited value.
  • the 14 volts present on capacitor 73 that is, the reference voltage
  • the toned sample input present on line 71 is connected directly to the negative input of OP AMP 74, and is connected through a voltage divider network to the negative input of OP AMP 75. If, for example, resistance levels R21 and R22 were equal, the potential at the negative input of OP AMP 75 would be the difference of 14 volts on line 71 and the 16 volts input, that is, 15 volts.
  • the 14-volt reference signal is placed on the positive input while the 14-volt toned sample signal is placed on the negative input. Since there is no differential, the output of OP AMP 74 indicates that the toner concentration condition is correct and the toner low signal remains off. Similarly, at OP AMP 75, the bare sample input is 14 volts, the toned sample input is 15 volts, and therefore the toner extra low signal remains.
  • the toned sample signal of 12 volts on line 71 is divided against 16 volts and if the resistances R21 and R22 were equal, would cause 14 volts to appear at the negative input of OP AMP 75. Since both inputs are 14 volts, the toner extra low signal remains off.
  • transistor Q8 is turned on by a high output from OP AMP 76.
  • a high output from OP AMP 76 is present whenever the output of OP AMP 77 is high (neglecting the RC time delay).
  • OP AMP 77 is high when the negative input is lower than the input on the positive side. Note that since line 66 is at 0 volts during regular operation, the voltage at the negative input of OP AMP 77 is lower than the positive side under normal conditions. Note, however, that when a bare or toned sample is taken, voltage on line 66 rises, thus turning off the high output from OP AMP 77, turning off the high output from OP AMP 76 and thus opening the circuit of transistor 08.
  • the toner replenisher 35 (FIGURE 3) operates to dump a quantity of toner into developer 23. If both the toner low and the toner extra low signals are activated, a variety of possibilities for further action are present, depending on machine design. For example, the first subsequent action would probably be to check a "cartridge empty" signal from the toner replenisher 35. If it is empty, a call for the key operator of the machine is in order. However, if the replenisher has an adequate toner supply, the next action might be to shut the machine down. Alternatively, there might be repeated toner density checks after a few more copies until the toner extra low signal is no longer active. At some point, if the extra low signal remains activated, the machine would be shut down.
  • a test cycle can be run on the shut-down cycle when only small numbers of reproductions are called for during a reproduction run.
  • Special test cycles with reproductions skipped may be used only during long, multi-copy runs.
  • Providing the specific control circuitry for interrupting machine operation to provide special test cycles at the proper time is dependent upon the requirements of a particular machine. Such circuit design is well within the skill of the art and does not comprise a part of the instant invention.
  • control apparatus for receiving the toner low and toner extra low signals to actuate the replenisher are well within the skill of the art and not a part of the invention herein.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Or Security For Electrophotography (AREA)

Claims (8)

1. Xerographischer Kopierer mit Einrichtungen (22, 23, 24, 25, 36) zur Erzeugung eines einheitlich mit Toner versehenen Testbereiches (30) und eines angrenzenden, im wesentlichen tonerfreien Bereiches auf einer wiederholt benutzbaren photoleitenden Abbildungsoberfläche (26), mit einer Abtasteinrichtung für die Abtastung der optischen Dichte der besagten Bereiche zur Erzeugung erster und zweiter Abtastsignale, welche die Dichte der besagten tonerfreien und mit Toner versehenen Bereiche darstellen, und mit einer auf die ersten und die zweiten Abtastsignale ansprechenden Steuereinrichtung (Figur 6), die ein Ausgangssignal abgibt, wenn die ersten und zweiten Abtastsignale um mehr als einen vorgegebenen Betrag voneinander abweichen, gekennzeichnet dadurch, daß der besagte Testbereich und der angrenzende tonerfreie Bereich innerhalb eines Teils (28) der Abbildungsoberfläche angeordnet sind, auf der Bilder der Originaldokumente erzeugt werden.
2. Xerographischer Kopierer nach Anspruch 1, dadurch gekennzeichnet, daß die Steuereinrichtung auf das besagte erste Abtastsignal anspricht, das eine optische Dichte im besagten tonerfreien Bereich anzeigt, die größer ist als ein vorbestimmter Wert, und ein Ausgangssignal liefert, das eine Verunreinigung der Abbildungsoberfläche anzeigt.
3. Xerographischer Kopierer nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die besagten Bereiche durch die Operation einer Vorsäuberungskorona (22) und die selektive Operation einer Löschlampe (24) erzeugt werden.
4. Xerographischer Kopierer nach Anspruch 3, gekennzeichnet durch einen Verschluß (36), der mit der Löschlampe verbunden ist und zur Festlegung des Testbereichs dient.
5. Xerographischer Kopierer nach einem der vorausgehenden Ansprüche, dadurch gekennzeichnet, daß der besagte Testbereich während eines Testzyklus gebildet wird, während dem keine Kopie erzeugt wird.
6. Xerographischer Kopierer nach Anspruch 5, dadurch gekennzeichnet, daß der Testzyklus nach Beendigung eines Kopienerzeugungslaufes von weniger als einer vorgegebenen Anzahl von Kopien ausgeführt wird.
7. Xerographischer Kopierer nach Anspruch 5, dadurch gekennzeichnet, daß der Testzyklus nach Unterbrechung der Erzeugung von Kopien in einem Kopienerzeugungslauf von mehr als einer vorgegebenen Anzahl von Kopien ausgeführt wird.
8. Xerographischer Kopierer nach einem der vorausgehenden Ansprüche, mit einer Entwicklungsstation (23), durch die eine Entwicklermischung aus Trägerpartikeln und Toner auf die Abbildungsoberfläche gebracht wird und mit einer Tonernachfülleinrichtung (35) zur Auffüllung der besagten Tonermischung, dadurch gekennzeichnet, daß die Tonernachfülleinrichtung auf die besagten Ausgangssignale anspricht.
EP19790100715 1978-04-10 1979-03-09 Xerographisches Kopiergerät Expired EP0004573B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US89495678A 1978-04-10 1978-04-10
US894957 1978-04-10
US05/894,955 US4183657A (en) 1978-04-10 1978-04-10 Dynamic reference for an image quality control system
US894955 1978-04-10
US05/894,957 US4178095A (en) 1978-04-10 1978-04-10 Abnormally low reflectance photoconductor sensing system
US894956 1978-04-10

Publications (2)

Publication Number Publication Date
EP0004573A1 EP0004573A1 (de) 1979-10-17
EP0004573B1 true EP0004573B1 (de) 1981-10-14

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Application Number Title Priority Date Filing Date
EP19790100715 Expired EP0004573B1 (de) 1978-04-10 1979-03-09 Xerographisches Kopiergerät

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DE (1) DE2960963D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4312589A (en) * 1979-11-19 1982-01-26 International Business Machines Corporation Charge density control for an electrostatic copier

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348522A (en) * 1962-08-28 1967-10-24 Xerox Corp Automatic toner control system
US3348523A (en) * 1965-04-07 1967-10-24 Xerox Corp Automatic toner control system
US3969114A (en) * 1973-07-26 1976-07-13 Xerox Corporation Method for monitoring copy quality
US4082445A (en) * 1975-11-21 1978-04-04 Xerox Corporation Toner control system for an electrostatic reproduction machine
GB1561923A (en) * 1976-12-31 1980-03-05 Xerox Corp Control system for an electrostatogrophic copying machine

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EP0004573A1 (de) 1979-10-17
DE2960963D1 (en) 1981-12-24

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RIN2 Information on inventor provided after grant (corrected)

Inventor name: CHAMPION, JAMES ROBERT

Inventor name: SEIGAL, STEVEN DAVID

Inventor name: ERNST, LARRY MASON

Inventor name: VAN CLEAVE, GEORGE WILLIAM

Inventor name: WILSON, CLEMENT CARD