EP0888579B1 - Process and arrangement for optimising charge pattern formation on a photoconductor - Google Patents

Process and arrangement for optimising charge pattern formation on a photoconductor Download PDF

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Publication number
EP0888579B1
EP0888579B1 EP97920571A EP97920571A EP0888579B1 EP 0888579 B1 EP0888579 B1 EP 0888579B1 EP 97920571 A EP97920571 A EP 97920571A EP 97920571 A EP97920571 A EP 97920571A EP 0888579 B1 EP0888579 B1 EP 0888579B1
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EP
European Patent Office
Prior art keywords
potential
exposure energy
determined
photoconductor
discharge potential
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
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EP97920571A
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German (de)
French (fr)
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EP0888579A1 (en
Inventor
Volkhard Maess
Martin Schleusener
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Canon Production Printing Germany GmbH and Co KG
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Oce Printing Systems GmbH and Co KG
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Publication of EP0888579A1 publication Critical patent/EP0888579A1/en
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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
    • G03G15/5045—Detecting the temperature
    • 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
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices
    • G03G15/0266—Arrangements for controlling the amount of charge
    • 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
    • G03G15/5037—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 the characteristics being an electrical parameter, e.g. voltage
    • 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
    • G03G2215/00071—Machine control, e.g. regulating different parts of the machine by measuring the photoconductor or its environmental characteristics
    • G03G2215/00084—Machine control, e.g. regulating different parts of the machine by measuring the photoconductor or its environmental characteristics the characteristic being the temperature

Definitions

  • the invention relates to a method for optimizing a Charge imaging on an electrophotographic photoconductor Printing and copying equipment.
  • electrophotographic printing devices are mostly in Connection with computer systems can be used and the possibilities of influence the operator on the print quality in this respect are low, exist in electrophotographic printing devices extremely high quality requirements. To this high To meet requirements, it is necessary to permissible tolerance ranges for electrophotographic processes to reduce.
  • electrophotographic printing devices print Cut sheets or continuous paper by placing on a photoconductor, which is preferably in the form of a drum latent image is generated.
  • the photoconductor is on a defined charging potential is charged.
  • the photoconductor selectively supplies energy, a latent image on the photoconductor generated by the charge in the areas of the photoconductor by exposure is reduced so far that this Areas in the subsequent printout with the so-called “charged area development "(CAD) remain white or the so-called” “Discharged area development” (DAD) colored with toner become.
  • CAD charged area development
  • DAD discharged area development
  • Following the exposure is on the photoconductor with the help of a developing device toner applied, the at the loaded areas (CAD process) or at the areas (DAD process) of the photoconductor stay.
  • the toner image on the photoconductor is then, for example transferred to paper or another record carrier and in a downstream fuser by heating melted into or with the record carrier due to adhesive forces arising when the toner image melts connected. After transferring the toner image to the The photoconductor is completely unloaded from the recording medium and cleaned of residual toner for subsequent preparation the next exposure fully on again set potential to be charged.
  • the discharge characteristic K1, K2 and thus the level of the potential of exposed areas on the photoconductor for example also due to production-related fluctuations, the quality of the photoconductor, its age, its temperature and the current process status, such as the beginning of a printing process, longer pauses between individual printing processes or different environmental influences affected.
  • US-A-4,855,766 describes a method for determining a optimal charging potential and an optimal exposure energy explained, in which the charging potential or Exposure energy gradually by a predetermined amount is increased until a setpoint is reached.
  • This procedure usually involves a large number of iteration steps perform until the setpoint for the difference from the discharge potential and the charging potential or the Setpoint for the rise in the discharge curve of the photoconductor at an optimal exposure energy is reached.
  • DE-OS 27 41 713 is a method for stabilization a charge image is known in the case of a given exposure energy the optimal charging potential with one or two iteration steps can be determined beforehand but coefficients of functions are to be determined from were derived from a model of the photoconductor and accordingly take into account a large number of influencing factors. Thereby the formulas become very complex and the computing time for the calculation of the coefficients increases. Ultimately, must six value groups of the charging potential and the discharging potential be measured until then by solving a system of equations the coefficients sought are determined can. However, the coefficients can still have large errors to have. Alternatively, one of the coefficients is used for the determination the recording of a large number of measured values is proposed, from which then with that from linear optimization known methods the searched coefficients with the required accuracy can be determined.
  • US-A-4,502,777 discloses a variety of physical Connections in a copying process and builds on it a comparatively complex procedure for correction the charging voltage or that of the charging unit flowing current without measuring the charging potential or the discharge potential is carried out.
  • the physical relationships When explaining the physical relationships also become an iteration process to determine the charging potential or by the charging device flowing current at constant exposure energy specified.
  • this iteration method has iteration steps Disadvantage that there is an approximately linear relationship between Discharge potential and exposure energy assumed.
  • the object of the invention is a simple method for Optimize charge image generation on a photoconductor of electrophotographic printing and copying equipment specify where the quality of printed images is independent of fluctuations in the quality and temperature of the photoconductor as well as independent of process state changes and one of them resulting change in the characteristic curve of the photoconductor.
  • the specified target value defined tolerance range lies, for example, a charging potential, which the Is potential to which the photoconductor is charged before exposure and / or one for exposing the photoconductor used exposure energy adjusted.
  • a charging potential which the Is potential to which the photoconductor is charged before exposure and / or one for exposing the photoconductor used exposure energy adjusted.
  • the charging potential and / or the exposure energy can, for example, use assignment tables can be achieved.
  • the assignment tables include, for example depending on various parameters Values to which the charging potential and / or the exposure energy can be set.
  • the parameters used are, for example, the temperature of the photoconductor that remains after a test exposure Discharge potential and a calculated or determined sensitivity factor the photoconductor layer.
  • the one to use to get the best print results Charging potential and / or the exposure energy to be used are thus calculated or preferably with the help one or more specific parameters from the assignment tables taken.
  • the tables include values determined empirically or calculated using formulas.
  • a photoconductor in electrophotographic printing and copying facilities will the photoconductor to a standard charging potential charged. Then one after exposure generated with standard exposure energy on the photoconductor Discharge potential and the temperature of the photoconductor measured. Following this, for example, using a microprocessor one sensitivity factor and one based exposure energy adapted to the sensitivity factor determined.
  • the photoconductor will open again the predetermined charging potential is charged with the determined adjusted exposure energy and then exposed generated discharge potential measured or determined. Is that generated discharge potential in the range of the predetermined setpoint, the charge pattern will be at that with the standard charging potential charged photoconductor generated by this is exposed with the adjusted exposure energy.
  • the temperature of the photoconductor is again determined a new sensitivity factor and a new one adjusted exposure energy calculated and the subsequent Checking process regarding the generated discharge potential repeated.
  • An iteration loop formed in this way becomes cycle through until the on the photoconductor after exposure generated discharge potential in the specified tolerance range, i.e. is in the range of the specified setpoint a charge image can be generated.
  • Difference value can be set, the difference value from the charging potential and the generated discharging potential calculated. This keeps the distance between charged and unloaded areas, of slight fluctuations aside, constant.
  • the predetermined maximum limit which in general is determined by the structure of the printer, so preferably the method steps specified in claim 6 carried out.
  • a charging potential is generated and measured.
  • the measured discharge potential then becomes one adapted charging potential determined with which of the photoconductor is charged, provided the adjusted charging potential is within a specified work area also generally determined by the technology used is.
  • the charge potential determined is determined charged photoconductor again with the maximum exposure energy exposed and the newly generated discharge potential determined. If this is within the specified tolerance range, so the charge pattern by means of the adjusted charging potential and the maximum exposure energy on the photoconductor generated.
  • the adjusted charging potential are redetermined and in an iteration loop Repeat the above steps until the Value of the discharge potential generated in the specified tolerance range lies.
  • the invention generates a charge pattern in that a photoconductor charged with minimal charging potential maximum exposure energy is exposed.
  • the photoconductor is charged with the specified potential charged and then with minimal exposure energy exposed. With the help of the generated and subsequently measured Discharge potential becomes an adapted charge potential calculated.
  • the adjusted charging potential is within of the given work area, the photoconductor charged to the adjusted charging potential, with minimal Exposure energy exposed and then the so generated Discharge potential determined again.
  • the generated discharge potential is not within the specified one Tolerance range, the adjusted charging potential newly determined and the steps explained above performed again.
  • This iteration loop is long repeated until the generated discharge potential within of the specified tolerance range and the charge pattern with the adjusted charging potential and the minimal exposure energy can be generated, or until the beginning of the Iteration loop calculated charging potential not within of the work area. In the latter case it will Charge pattern using the maximum charging potential and the generated minimal exposure energy.
  • the influence of all influencing factors which the Influence the characteristic of the photoconductor is taken into account. It is also advantageous in the method according to the invention that the temperature of the photoconductor is not kept constant and the operating costs of electrophotographic Printing device are lower.
  • Another advantage of the method according to the invention is in that grid or fine lines even with different Characteristic curves of photoconductors reproduced with constant quality become. This also extends the useful life of photoconductors, since these are also less favorable due to aging Characteristic curves still used and still used can be.
  • the invention also relates to an arrangement for optimization charge image generation and in particular for performing the inventive method.
  • the above technical Effects also apply to the arrangement, which is preferred built into a printer or copier.
  • FIG. 1 shows a potential-time diagram of different characteristic curves K1, K2 of a photoconductor, the potential V of the photoconductor being plotted on an ordinate and the process time t on the abscissa.
  • a time t 0 indicates the start of charging a photoconductor to a potential V 1 , which is reached at a time t 1 .
  • the charge on the photoconductor can decrease to a potential V 2 due to environmental influences. From time t 2 , the photoconductor is exposed.
  • the potential present on the photoconductor decreases to a potential V D1 or V D2 along a characteristic curve K1 or K2 in a time period from t2 to t3.
  • the charge image begins to develop using toner in the developer station.
  • V D1 or V D2 discharge potentials V D1 or V D2 are present on the photoconductor depending on the characteristic curves K1 or K2 for the start of development.
  • the characteristic curves K1 and K2 are exemplary characteristic curves, that is to say, after an exposure, at time t 3 , areas with other potentials that deviate from V D1 or V D2 can also be present.
  • the different course of the characteristic curves K1 and K2 or more photoconductors depends on environmental conditions, like the temperature, of manufacturing-related Variations in the quality of the photoconductor and its Age or from the current process status, such as the start of printing or the pause of a pause between individual printing processes.
  • the Characteristic curve K1 for example, a photoconductor that is relative is insensitive and / or cold.
  • the characteristic describes K2 a photoconductor that is more sensitive and / or warmer than the photoconductor described by the characteristic curve K1.
  • FIGS. 2a to 2c are flow diagrams of a preferred implementation of the method according to the invention.
  • the photoconductor is charged to the standard charging potential V C s in V (volts) (step 1a), which is kept constant by means of a known charging control.
  • the exposure is then set to a standard exposure energy H S in ⁇ Ws / cm 2 and the photoconductor H S is exposed (step 1b). If the exposure process is completed before or at the latest at time t 3 (see FIG. 1), the residual or discharge potential V D is measured at time t 3 (step 1c).
  • the discharge potential V D in V at time t 3 corresponds, for example, to one of the values V D1 or V D2 of a discharge potential which, depending on the characteristic curve K1 or K2 of a photoconductor, remains as a residual potential on the photoconductor after exposure (see FIG. 1).
  • the temperature T of the photoconductor in step 2 measured.
  • the temperature can also be increased to a later one or earlier.
  • a sensitivity factor K and, based on the sensitivity factor K, an adapted exposure energy H a in ⁇ Ws / cm 2 are calculated (step 3).
  • the sensitivity factor K can be calculated, for example, as a function of the instantaneous charging potential V C , the temperature T, the instantaneous exposure energy H, the measured discharging potential V D and a lowest achievable discharging potential V lim as:
  • An adapted exposure energy H a is then preferably calculated using equation (2) on the basis of the sensitivity factor K as: where V D is the target value for the discharge potential V D.
  • step 4 it is checked whether the exposure energy H a adjusted in step 3 is less than the maximum or greater than the minimum exposure energy H max or H min that can be set with the used or available exposure unit or is equal to one of these limit values. Is H a outside this range, then the later with reference to figures 2b and 2c performed steps.
  • the photoconductor is recharged to the standard charging potential V C s in a step 5a analogous to step 1a. After completion of the charging of the photoconductor is matched with the calculated exposure energy H a exposed (step 5b '). Then the discharge potential V D generated on the photoconductor is measured.
  • step 6 the measured in step 5c discharge potential V D with the desired potential V D to compare (see Figure 1).
  • step 7 Is the discharge potential generated V D within a predetermined tolerance range, that is the discharge potential generated V D differs only slightly from the desired potential V D to off, a charge image is subsequently thereto (step 7) by the photoconductor to the standard Charging potential V C s is loaded and then exposed with the adapted exposure energy H a .
  • step 5c If the discharge potential V D generated in step 5c is not within the predetermined tolerance range, then an iteration cycle with the discharge potential V D measured in step 5c and the adjusted exposure energy H a calculated in step 3 is required, in which steps 2 to 6 are carried out again become.
  • step 7 a charge image is generated by charging the photoconductor to the standard charging potential V C S and exposing it with the appropriately adapted exposure energy H a .
  • Step 4 "no" are those based on FIGS. 2b and 2c steps described below.
  • a step 4 ' will decide whether the adjusted exposure energy H a calculated in step 3 (see FIG. 2 a) is greater than a maximum permissible exposure energy H max . If the decision made in step 4 'is "no", ie if the adjusted exposure energy is less than a minimum permissible exposure energy H min , the part of the flowchart described later with reference to FIG. 2c is carried out.
  • step 8a If the adjusted exposure energy H a is greater than the maximum exposure energy H max , the decision is "yes" and the photoconductor is charged in step 8a according to step 1a to the standard charging potential V C s and in contrast to steps 1b and 5b 'then exposed with maximum exposure energy H max (step 8b'').
  • the discharge potential V D generated on the photoconductor is then determined (step 8c).
  • step 9 an adapted charging potential V C a is then determined, which, for example, either according to equation (3) or according to equation (4) can be calculated.
  • the instantaneous sensitivity factor K calculated using equation (1) is used in equations (3) or (4).
  • step 10 a decision is made as to whether the adjusted charging potential V C a is within a working range or not.
  • step 10 If the decision in step 10 is "yes", the photoconductor is charged with the adapted charging potential V C a calculated in step 9 (step 11a '), then exposed with maximum exposure energy H max (step 11b') and in step 11c the discharge potential V D determined.
  • step 12 analogously to step 6, it is examined whether the discharge potential V D is within a predetermined tolerance range. If this is the case, the charge image is generated with the adapted charging potential V C a and by exposure with maximum exposure energy H max (step 13).
  • step 10 If, however, the decision in step 10 is "no" already on the first pass or after passing through one or more iteration loops (steps 9 to 12), the photoconductor is charged with a minimal charging potential V C min and then exposed with maximum exposure energy H max (step 14).
  • step 4 '(FIG. 2b) is "no"
  • step 3 the minimum exposure energy H min .
  • step 8b ''' in contrast to step 8b''in FIG. 2b, the photoconductor is not exposed with maximum, but with minimum exposure energy H min . If the result of the decision in step 10 is "no", step 14 'is carried out in the part of the flowchart shown in FIG. 2c, in which a charge image is generated on the photoconductor charged to maximum charging potential V C max by means of minimal exposure energy H min ,

Description

Die Erfindung betrifft ein Verfahren zum Optimieren einer Ladungsbilderzeugung auf einem Fotoleiter von elektrofotografischen Druck- und Kopiereinrichtungen.The invention relates to a method for optimizing a Charge imaging on an electrophotographic photoconductor Printing and copying equipment.

An die mittels elektrofotografischen Druckeinrichtungen erzielbaren Druckergebnisse werden, verglichen mit den mittels elektrofotografischen Kopiergeräten erzielbaren Kopierergebnissen, vom Benutzer erheblich höhere Qualitätsanforderungen gestellt. Von Benutzern der Kopiergeräte werden daher auch Kopierergebnisse akzeptiert, die verglichen mit der Kopiervorlage etwas schlechter sind.To those that can be achieved by means of electrophotographic printing devices Print results are compared with the means copy results achievable with electrophotographic copiers, significantly higher quality requirements from the user posed. So users of the copiers will also Copy results accepted compared to the copy template are a little worse.

Da elektrofotografische Druckeinrichtungen jedoch zumeist in Verbindung mit EDV-Anlagen verwendet werden und die Einflußmöglichkeiten des Bedieners auf die Druckqualität insofern gering sind, bestehen bei elektrofotografischen Druckeinrichtungen äußerst hohe Qualitätsanforderungen. Um diesen hohen Anforderungen gerecht zu werden, ist es erforderlich, die zulässigen Toleranzbereiche bei elektrofotografischen Prozessen zu verringern.However, since electrophotographic printing devices are mostly in Connection with computer systems can be used and the possibilities of influence the operator on the print quality in this respect are low, exist in electrophotographic printing devices extremely high quality requirements. To this high To meet requirements, it is necessary to permissible tolerance ranges for electrophotographic processes to reduce.

Elektrofotografische Druckeinrichtungen bedrucken beispielsweise Einzelblätter oder Endlospapier, indem auf einem Fotoleiter, der vorzugsweise die Form einer Trommel hat, ein latentes Bild erzeugt wird. Hierzu wird der Fotoleiter auf ein definiertes Aufladepotential aufgeladen. Anschließend wird mittels einer Belichtungseinrichtung, die dem Fotoleiter punktuell Energie zuführt, ein latentes Bilda auf dem Fotoleiter erzeugt, indem die Ladung in den Bereichen des Fotoleiters durch Belichten soweit verringert wird, daß diese Bereiche im anschließenden Ausdruck beim sogenannten "charged area development" (CAD) weiß bleiben bzw. beim sogenannten "discharged area development" (DAD) mit Toner eingefärbt werden. Im Anschluß an das Belichten wird auf den Fotoleiter mit Hilfe einer Entwicklungseinrichtung Toner aufgebracht, der an den geladenen Bereichen (CAD-Verfahren) bzw. an den entladenen Bereichen (DAD-Verfahren) des Fotoleiters haften bleiben.For example, electrophotographic printing devices print Cut sheets or continuous paper by placing on a photoconductor, which is preferably in the form of a drum latent image is generated. For this, the photoconductor is on a defined charging potential is charged. Subsequently is by means of an exposure device that the photoconductor selectively supplies energy, a latent image on the photoconductor generated by the charge in the areas of the photoconductor by exposure is reduced so far that this Areas in the subsequent printout with the so-called "charged area development "(CAD) remain white or the so-called" "Discharged area development" (DAD) colored with toner become. Following the exposure is on the photoconductor with the help of a developing device toner applied, the at the loaded areas (CAD process) or at the areas (DAD process) of the photoconductor stay.

Das Tonerbild auf dem Fotoleiter wird anschließend beispielsweise auf Papier oder einen anderen Aufzeichnungsträger übertragen und in einer nachgeordneten Fixierstation durch Erwärmen in den Aufzeichnungsträger eingeschmolzen oder mit diesem durch beim Schmelzen des Tonerbildes entstehende Adhäsionskräfte verbunden. Nach Übertragen des Tonerbildes auf den Aufzeichnungsträger wird der Fotoleiter vollständig entladen und von restlichem Toner gereinigt, um anschließend zur Vorbereitung der nächsten Belichtung wieder vollständig auf ein festgelegtes Potential aufgeladen zu werden.The toner image on the photoconductor is then, for example transferred to paper or another record carrier and in a downstream fuser by heating melted into or with the record carrier due to adhesive forces arising when the toner image melts connected. After transferring the toner image to the The photoconductor is completely unloaded from the recording medium and cleaned of residual toner for subsequent preparation the next exposure fully on again set potential to be charged.

Wie Figur 1 veranschaulicht, nimmt beim Belichten des Fotoleiters dessen Potential von einem Aufladepotential V2, auf das der Fotoleiter vor dem Belichten geladen wurde und das mittels einer Aufladungsregelung konstant gehalten werden kann, entlang einer Kennlinie K1 bzw. K2 bis auf ein erheblich niedrigeres Potential VD1 bzw. VD2 ab. Das Potential belichteter Bereiche hängt einerseits von der Höhe der Belichtungsenergie, der Belichtungsdauer und der Höhe des Aufladepotentials V2 ab.As illustrated in Figure 1, takes on exposure of the photoconductor its potential from a charging potential V2 that the photoconductor was loaded before exposure and that be kept constant by means of a charge control can, along a characteristic curve K1 or K2 to a considerable extent lower potential VD1 or VD2. The potential exposed areas depends on the one hand on the amount of exposure energy, the exposure time and the level of the charging potential V2 from.

Andererseits wird die Entladungskennlinie K1, K2 und damit die Höhe des Potentials belichteter Bereiche auf dem Fotoleiter beispielsweise auch durch fertigungsbedingte Schwankungen, die Qualität des Fotoleiters, dessen Alter, dessen Temperatur sowie durch den aktuellen Prozeßzustand, wie beispielsweise den Anfang eines Druckvorgangs, längere Pausen zwischen einzelnen Druckvorgängen oder unterschiedliche Umgebungseinflüsse beeinflußt. Hieraus ergeben sich Potential-Schwankungen VD1, VD2 der belichteten Bereiche des Fotoleiters, die aufgrund der dadurch bedingten unterschiedlichen Toneraufnahme in der Entwicklungseinheit zu Qualitätsschwankungen eines herzustellenden Druckbildes führen.On the other hand, the discharge characteristic K1, K2 and thus the level of the potential of exposed areas on the photoconductor for example also due to production-related fluctuations, the quality of the photoconductor, its age, its temperature and the current process status, such as the beginning of a printing process, longer pauses between individual printing processes or different environmental influences affected. This results in fluctuations in potential VD1, VD2 of the exposed areas of the photoconductor, the different due to the resulting Toner absorption in the development unit due to quality fluctuations of a print image to be produced.

Zum Ausgleich von Temperaturschwankungen ist es bekannt, den Fotoleiter während des gesamten Betriebs auf konstanter Temperatur zu halten. Teilweise wird der Fotoleiter sogar ununterbrochen auf konstanter Temperatur gehalten. Nachteilig ist hierbei, daß eine entsprechende Heizung vorgesehen sein muß, durch die erhöhte Energiekosten entstehen. Außerdem wird durch die Heizung nur einer der vorstehend genannten Einflußfaktoren beeinflußt.It is known to compensate for temperature fluctuations Photoconductor at constant temperature throughout the operation to keep. Sometimes the photoconductor is even continuously kept at constant temperature. The disadvantage is here that an appropriate heating must be provided, caused by the increased energy costs. Besides, will by heating only one of the factors mentioned above affected.

Es ist weiterhin bekannt, zum Ausgleich von Qualitätsschwankungen des Druckbildes in Abhängigkeit von bestimmten Parameter die Tonerkonzentration zu variieren. Hiermit können allerdings nicht sämtliche Qualitätsschwankungen ausgeglichen werden. Insbesondere können durch ein Verändern der Tonerkonzentration Raster- oder Feinlinien-Wiedergaben nicht in gleicher Weise konstant gehalten werden.It is also known to compensate for quality fluctuations of the printed image depending on certain parameters to vary the toner concentration. Hereby, however not all quality fluctuations compensated become. In particular, by changing the toner concentration Raster or fine line renditions not in the same Way to be kept constant.

Aus dem japanischen Dokument JP 6-230642 (A) bzw. der zugehörigen japanischen Patentanmeldung HEI sei 5-15327 ist ein Verfahren bekannt, bei dem zum Optimieren der Ladungsbilderzeugung die Entladekennlinie des Fotoleiters abhängig von der Belichtungsenergie durch mehrmaliges Messen des Entladepotentials bei unterschiedlichen Belichtungsenergien und eine anschließende Approximation zwischen den Meßwerten bestimmt wird. Nachteilig ist, daß sowohl mehrere Messungen benötigt werden, und außerdem anschließend approximiert werden muß, um den optimalen Wert für die Belichtungsenergie zu ermitteln.From Japanese document JP 6-230642 (A) or the associated Japanese patent application HEI is 5-15327 is a Known method in which to optimize charge image generation the discharge characteristic of the photoconductor depends on the Exposure energy by measuring the discharge potential several times at different exposure energies and one subsequent approximation between the measured values is determined becomes. The disadvantage is that both measurements are required , and must also be approximated subsequently in order to to determine the optimal value for the exposure energy.

In der US-A-4,855,766 wird ein Verfahren zum Ermitteln eines optimalen Aufladepotentials und einer optimalen Belichtungsenergie erläutert, bei dem das Aufladepotential bzw. die Belichtungsenergie schrittweise um einen vorgegebenen Betrag erhöht wird, bis ein Sollwert erreicht ist. Somit sind bei diesem Verfahren in der Regel eine Vielzahl von Iterationsschritten durchzuführen, bis der Sollwert für die Differenz aus dem Entladepotential und dem Aufladepotential bzw. der Sollwert für den Anstieg der Entladekurve des Fotoleiters bei einer optimalen Belichtungsenergie erreicht ist.US-A-4,855,766 describes a method for determining a optimal charging potential and an optimal exposure energy explained, in which the charging potential or Exposure energy gradually by a predetermined amount is increased until a setpoint is reached. Thus at This procedure usually involves a large number of iteration steps perform until the setpoint for the difference from the discharge potential and the charging potential or the Setpoint for the rise in the discharge curve of the photoconductor at an optimal exposure energy is reached.

Aus DE-OS 27 41 713 ist ein Verfahren zur Stabilisierung eines Ladungsbildes bekannt, bei dem bei vorgegebener Belichtungsenergie das optimale Aufladepotential zwar mit einem oder zwei Iterationsschritten ermittelt werden kann, zuvor aber Koeffizienten von Funktionen zu bestimmen sind, die aus einem Modell des Fotoleiters abgeleitet wurden und demzufolge eine Vielzahl von Einflußgrößen berücksichtigen. Dadurch werden die Formeln aber sehr komplex und die Rechenzeit für die Berechnung der Koeffizienten steigt. Letztlich müssen sechs Wertegruppen des Aufladepotentials und des Entladepotentials gemessen werden, bis dann durch Auflösen eines Gleichungssystems die gesuchten Koeffizienten ermittelt werden können. Die Koeffizienten können dann aber noch große Fehler haben. Alternativ wird für die Bestimmung eines der Koeffizienten jeweils die Aufnahme einer Vielzahl von Meßwerten vorgeschlagen, aus denen dann mit den aus der linearen Optimierung bekannten Verfahren die gesuchten Koeffizienten mit der erforderlichen Genauigkeit ermittelt werden.DE-OS 27 41 713 is a method for stabilization a charge image is known in the case of a given exposure energy the optimal charging potential with one or two iteration steps can be determined beforehand but coefficients of functions are to be determined from were derived from a model of the photoconductor and accordingly take into account a large number of influencing factors. Thereby the formulas become very complex and the computing time for the calculation of the coefficients increases. Ultimately, must six value groups of the charging potential and the discharging potential be measured until then by solving a system of equations the coefficients sought are determined can. However, the coefficients can still have large errors to have. Alternatively, one of the coefficients is used for the determination the recording of a large number of measured values is proposed, from which then with that from linear optimization known methods the searched coefficients with the required accuracy can be determined.

Die US-A-4,502,777 offenbart eine Vielzahl von physikalischen Zusammenhängen bei einem Kopiervorgang und gibt darauf aufbauend ein vergleichsweise aufwendiges Verfahren zur Korrektur der Aufladespannung bzw. des durch die Aufladeeinheit fließenden Stromes an, das ohne Messung des Aufladepotentials oder des Entladepotentials durchgeführt wird. Beim Erläutern der physikalischen Zusammenhänge wird auch ein Iterationsverfahren zur Bestimmung des Aufladepotentials bzw. des durch die Aufladevorrichtung fließenden Stroms bei konstanter Belichtungsenergie angegeben. Neben den mehrfach auszuführenden Iterationsschritten hat dieses Iterationsverfahren jedoch den Nachteil, daß es einen etwa linearen Zusammenhang zwischen Entladepotential und Belichtungsenergie unterstellt.US-A-4,502,777 discloses a variety of physical Connections in a copying process and builds on it a comparatively complex procedure for correction the charging voltage or that of the charging unit flowing current without measuring the charging potential or the discharge potential is carried out. When explaining the physical relationships also become an iteration process to determine the charging potential or by the charging device flowing current at constant exposure energy specified. In addition to the multiple executions However, this iteration method has iteration steps Disadvantage that there is an approximately linear relationship between Discharge potential and exposure energy assumed.

Es ist Aufgabe der Erfindung ein einfaches Verfahren zum Optimieren einer Ladungsbilderzeugung auf einem Fotoleiter von elektrofotografischen Druck- und Kopiereinrichtungen anzugeben, bei dem die Qualität von Druckbildern unabhängig von Qualitäts- und Temperaturschwankungen des Fotoleiters sowie unabhängig von Prozeßzustandsänderungen und einer daraus resultierenden Kennlinienveränderung des Fotoleiters ist.The object of the invention is a simple method for Optimize charge image generation on a photoconductor of electrophotographic printing and copying equipment specify where the quality of printed images is independent of fluctuations in the quality and temperature of the photoconductor as well as independent of process state changes and one of them resulting change in the characteristic curve of the photoconductor.

Gemäß der Erfindung ist dies bei einem Verfahren zum Optimieren einer Ladungsbilderzeugung auf einem Fotoleiter von elektrofotografischen Druck- und Kopiereinrichtungen durch die Merkmale in Anspruch 1 oder 6 erreicht. Vorteilhafte Weiterbildungen sind Gegenstand der auf den Anspruch 1 oder 6 unmittelbar oder mittelbar rückbezogenen abhängigen Ansprüche.According to the invention, this is in a method for optimization charge image generation on a photoconductor of electrophotographic Printing and copying equipment by the Features achieved in claim 1 or 6. Advantageous further training are the subject of claims 1 or 6 directly or indirectly related dependent claims.

Gemäß dem erfindungsgemäßen Verfahren wird ein nach einem Belichten eines Fotoleiters auf diesem vorhandenes Rest- bzw. Entladepotential auf einen vorgegebenen Sollwert eingestellt, von dem nur in engen Grenzen geringe Abweichungen zulässig sind.According to the method of the invention, one after one Exposing a photoconductor to any remaining or Discharge potential set to a predetermined setpoint, from which slight deviations are only permitted within narrow limits are.

Um ein Entladepotential zu erreichen, das innerhalb des um den vorgegebenen Sollwert definiereten Toleranzbereichs liegt, wird beispielsweise ein Aufladepotential, welches das Potential ist, auf das der Fotoleiter vor dem Belichten aufgeladen wird, und/oder eine zum Belichten des Fotoleiters verwendete Belichtungsenergie angepaßt. Eine derartige Anpassung des Aufladepotentials und/oder der Belichtungsenergie kann beispielsweise unter Verwenden von Zuweisungstabellen erreicht werden. die Zuweisungstabellen enthalten beispielsweise in Abhängigkeit verschiedener Parameter entsprechende Werte, auf welche das Aufladepotential und/oder die Belichtungsenergie eingestellt werden. In order to achieve a discharge potential within the order the specified target value defined tolerance range lies, for example, a charging potential, which the Is potential to which the photoconductor is charged before exposure and / or one for exposing the photoconductor used exposure energy adjusted. Such an adjustment the charging potential and / or the exposure energy can, for example, use assignment tables can be achieved. the assignment tables include, for example depending on various parameters Values to which the charging potential and / or the exposure energy can be set.

Die verwendeten Parameter sind beispielsweise die Temperatur des Fotoleiters, das nach einer Testbelichtung verbleibende Entladepotential und ein berechneter oder bestimmter Empfindlichkeitsfaktor der Fotoleiterschicht.The parameters used are, for example, the temperature of the photoconductor that remains after a test exposure Discharge potential and a calculated or determined sensitivity factor the photoconductor layer.

Das zur Erzielung optimaler Druckergebnisse zu verwendende Aufladepotential und/oder die zu verwendende Belichtungsenergie werden somit berechnet oder vorzugsweise unter Zuhilfenahme einer oder mehrerer bestimmter Parameter aus den Zuweisungstabellen entnommen. Die Tabellen enthalten beispielsweise empirisch bestimmte oder mittels Formeln berechnete Werte.The one to use to get the best print results Charging potential and / or the exposure energy to be used are thus calculated or preferably with the help one or more specific parameters from the assignment tables taken. For example, the tables include values determined empirically or calculated using formulas.

Beim Verfahren zum Optimieren einer Ladungsbilderzeugung auf einem Fotoleiter in elektrofotografischen Druck- und Kopiereinrichtungen wird der Fotoleiter auf ein Standard-Aufladepotential aufgeladen. Anschließend wird ein nach dem Belichten mit Standard-Belichtungsenergie auf dem Fotoleiter erzeugtes Entladepotential und die Temperatur des Fotoleiters gemessen. Im Anschluß hieran werden beispielsweise mittels eines Mikroprozessors ein Empfindlichkeitsfaktor und eine auf der Basis des Empfindlichkeitsfaktors angepaßte Belichtungsenergie ermittelt.In the process of optimizing charge imaging a photoconductor in electrophotographic printing and copying facilities will the photoconductor to a standard charging potential charged. Then one after exposure generated with standard exposure energy on the photoconductor Discharge potential and the temperature of the photoconductor measured. Following this, for example, using a microprocessor one sensitivity factor and one based exposure energy adapted to the sensitivity factor determined.

Bei einer Weiterbildung des Verfahrens gemäß der Erfindung wird geprüft, ob die ermittelte Belichtungsenergie zwischen einer maximal und einer minimal zulässigen Belichtungsenergie liegt. Ist dies der Fall, so wird der Fotoleiter erneut auf das vorgegebene Aufladepotential geladen, mit der ermittelten angepaßten Belichtungsenergie belichtet und anschließend das erzeugte Entladepotential gemessen bzw. bestimmt. Liegt das erzeugte Entladepotential im Bereich des vorgegebenen Sollwerts, wird das Ladungsbild auf dem mit dem Standard-Aufladepotential geladenen Fotoleiter dadurch erzeugt, daß dieser mit der angepaßten Belichtungsenergie belichtet wird.In a further development of the method according to the invention it is checked whether the determined exposure energy between a maximum and a minimum allowable exposure energy lies. If this is the case, the photoconductor will open again the predetermined charging potential is charged with the determined adjusted exposure energy and then exposed generated discharge potential measured or determined. Is that generated discharge potential in the range of the predetermined setpoint, the charge pattern will be at that with the standard charging potential charged photoconductor generated by this is exposed with the adjusted exposure energy.

Weicht das erzeugte Entladepotential zu weit von dem vorgegebenen Sollwert ab, wird erneut die Temperatur des Fotoleiters bestimmt, ein neuer Empfindlichkeitsfaktor und eine neue angepaßte Belichtungsenergie berechnet und der anschließende Überprüfungsprozeß bezüglich des erzeugten Entladepotentials wiederholt. Eine hierdurch gebildete Iterationsschleife wird so oft durchlaufen, bis das auf dem Fotoleiter nach dem Belichten erzeugte Entladepotential im vorgegebenen Toleranzbereich, d.h. im Bereich des vorgegebenen Sollwerts, liegt und ein Ladungsbild erzeugt werden kann.If the discharge potential generated deviates too far from the specified one Desired value, the temperature of the photoconductor is again determined a new sensitivity factor and a new one adjusted exposure energy calculated and the subsequent Checking process regarding the generated discharge potential repeated. An iteration loop formed in this way becomes cycle through until the on the photoconductor after exposure generated discharge potential in the specified tolerance range, i.e. is in the range of the specified setpoint a charge image can be generated.

Statt einen Toleranzbereich mit Hilfe eines vorgegebenen Sollwerts festzulegen, kann dieser auch durch einen vorgegebenen Differenzwert festgelegt werden, wobei sich der Differenzwert aus dem Aufladepotential und dem erzeugten Entladepotential berechnet. Somit bleibt der Abstand zwischen aufgeladenen und entladenen Bereichen, von geringen Schwankungen abgesehen, konstant.Instead of a tolerance range using a given one To set the target value, this can also be specified by a predetermined value Difference value can be set, the difference value from the charging potential and the generated discharging potential calculated. This keeps the distance between charged and unloaded areas, of slight fluctuations aside, constant.

Überschreitet jedoch die berechnete, angepaßte Belichtungsenergie den vorgegebenen maximalen Grenzwert, der im allgemeinen durch den Aufbau des Druckers festgelegt ist, so werden vorzugsweise die im Patentanspruch 6 angegebenen Verfahrensschritte durchgeführt.However, exceeds the calculated, adjusted exposure energy the predetermined maximum limit, which in general is determined by the structure of the printer, so preferably the method steps specified in claim 6 carried out.

Mit einer maximalen Belichtungsenergie und dem vorgegebenen Aufladepotential wird ein Entladepotential erzeugt und gemessen. Aus dem gemessenen Entladepotential wird danach ein angepaßtes Aufladepotential ermittelt, mit welchem der Fotoleiter aufgeladen wird, sofern das angepaßte Aufladepotential innerhalb eines vorgegebenen Arbeitsbereiches liegt, der ebenfalls im allgemeinen durch die eingesetzte Technik vorgegeben ist.With a maximum exposure energy and the specified one A charging potential is generated and measured. The measured discharge potential then becomes one adapted charging potential determined with which of the photoconductor is charged, provided the adjusted charging potential is within a specified work area also generally determined by the technology used is.

Bei einer Weiterbildung wird der auf das ermittelte Aufladepotential geladene Fotoleiter wieder mit der maximalen Belichtungsenergie belichtet und das neu erzeugte Entladepotential ermittelt. Liegt dieses im vorgegebenen Toleranzbereich, so wird das Ladungsbild mittels des angepaßten Aufladepotentials und der maximalen Belichtungsenergie auf dem Fotoleiter erzeugt.In the case of further training, the charge potential determined is determined charged photoconductor again with the maximum exposure energy exposed and the newly generated discharge potential determined. If this is within the specified tolerance range, so the charge pattern by means of the adjusted charging potential and the maximum exposure energy on the photoconductor generated.

Wenn das erzeugte Entladepotential jedoch nicht im vorgegebenen Toleranzbereich liegt, wird das angepaßte Aufladepotential neu bestimmt und in einer Iterationsschleife werden die vorstehend erläuterten Schritte so oft wiederholt, bis der Wert des erzeugten Entladepotentials im vorgegebenen Toleranzbereich liegt.However, if the generated discharge potential is not within the specified range Tolerance range, the adjusted charging potential are redetermined and in an iteration loop Repeat the above steps until the Value of the discharge potential generated in the specified tolerance range lies.

Sollte das berechnete angepaßte Aufladepotential nach einer vorgegebenen Anzahl Iterationen dennoch außerhalb des festgelegten Arbeitsbereiches liegen, wird bei einer anderen Weiterbildung der Erfindung ein Ladungsbild dadurch erzeugt, daß ein mit minimalem Aufladepotential geladener Fotoleiter mit maximaler Belichtungsenergie belichtet wird.Should the calculated adjusted charging potential after a specified number of iterations outside the specified number Work area, is with another training the invention generates a charge pattern in that a photoconductor charged with minimal charging potential maximum exposure energy is exposed.

Unterschreitet hingegen die gemäß dem Verfahren nach der Erfindung berechnete, angepaßte Belichtungsenergie den vorgegebenen minimalen Grenzwert, so werden vorzugsweise ebenfalls die in Patentanspruch 6 angegebenen Schritte durchgeführt, wobei jedoch anstelle der minimalen Belichtungsenergie die maximale Belichtungsenergie verwendet wird.However, falls below that according to the procedure according to Invention calculated, adjusted exposure energy to the given minimum limit, so are also preferred performed the steps specified in claim 6, however, instead of the minimum exposure energy the maximum exposure energy is used.

Der Fotoleiter wird mit dem vorgegebenen Aufladepotential aufgeladen und anschließend mit minimaler Belichtungsenergie belichtet. Mithilfe des somit erzeugten und nachfolgend gemessenen Entladepotentials wird ein angepaßtes Aufladepotential berechnet. Liegt das angepaßte Aufladepotential innerhalb des vorgegebenen Arbeitsbereichs, wird der Fotoleiter auf das angepaßte Aufladepotential aufgeladen, mit minimaler Belichtungsenergie belichtet und anschließend das so erzeugte Entladepotential erneut bestimmt.The photoconductor is charged with the specified potential charged and then with minimal exposure energy exposed. With the help of the generated and subsequently measured Discharge potential becomes an adapted charge potential calculated. The adjusted charging potential is within of the given work area, the photoconductor charged to the adjusted charging potential, with minimal Exposure energy exposed and then the so generated Discharge potential determined again.

Liegt das neu bestimmte Entladepotential innerhalb eines vorgegebenen Toleranzbereichs, so wird das Ladungsbild mithilfe des angepaßten Aufladepotentials und der minimalen Belichtungsenergie erzeugt.If the newly determined discharge potential lies within a specified tolerance range, so the charge pattern using the adjusted charging potential and the minimum Exposure energy generated.

Liegt das erzeugte Entladepotential jedoch nicht in dem vorgegebenen Toleranzbereich, wird das angepaßte Aufladepotential neu bestimmt und die vorstehend erläuterten Schritte werden erneut durchgeführt. Diese Iterationsschleife wird solange wiederholt, bis das erzeugte Entladepotential innerhalb des vorgegebenen Toleranzbereichs liegt und das Ladungsbild mit dem angepaßten Aufladepotential und der minimalen Belichtungsenergie erzeugt werden kann, oder bis das zu Beginn der Iterationsschleife berechnete Aufladepotential nicht innerhalb des Arbeitsbereichs liegt. Im letzteren Fall wird das Ladungsbild mithilfe des maximalen Aufladepotentials und der minimalen Belichtungsenergie erzeugt.However, the generated discharge potential is not within the specified one Tolerance range, the adjusted charging potential newly determined and the steps explained above performed again. This iteration loop is long repeated until the generated discharge potential within of the specified tolerance range and the charge pattern with the adjusted charging potential and the minimal exposure energy can be generated, or until the beginning of the Iteration loop calculated charging potential not within of the work area. In the latter case it will Charge pattern using the maximum charging potential and the generated minimal exposure energy.

Bei dem erfindungsgemäßen Verfahren ist insbesondere vorteilhaft, daß der Einfluß sämtlicher Einflußfaktoren, welche die Kennlinie des Fotoleiters beeinflussen, berücksichtigt ist. Außerdem ist bei dem erfindungsgemäßen Verfahren vorteilhaft, daß die Temperatur des Fotoleiters nicht konstant gehalten werden muß und insofern die Betriebskosten der elektrofotografischen Druckeinrichtung niedriger sind.In the method according to the invention, it is particularly advantageous that the influence of all influencing factors which the Influence the characteristic of the photoconductor is taken into account. It is also advantageous in the method according to the invention that the temperature of the photoconductor is not kept constant and the operating costs of electrophotographic Printing device are lower.

Ein weiterer Vorteil des erfindungsgemäßen Verfahrens besteht darin, daß Raster- oder Feinlinien auch bei unterschiedlichen Kennlinien von Fotoleitern mit konstanter Qualtität wiedergegeben werden. Dadurch verlängert sich auch die Nutzungsdauer von Fotoleitern, da diese auch bei alterungsbedingten ungünstigeren Kennlinienverläufen noch verwendet und weiter benutzt werden können.Another advantage of the method according to the invention is in that grid or fine lines even with different Characteristic curves of photoconductors reproduced with constant quality become. This also extends the useful life of photoconductors, since these are also less favorable due to aging Characteristic curves still used and still used can be.

Des weiteren findet ein Erfassen von Daten und die Durchführung des erfindungsgemäßen Verfahrens automatisch statt. Da das erfindungsgemäße Verfahren sehr schnell abläuft, kann ein Überprüfen der kritischen Parameter, vorzugsweise nicht nur nach Einschalten eines Druckers, nach Druckpausen oder nach Auswechseln eines Fotoleiters, sondern auch während des Druckbetriebs in geeigneten Zeitabständen durchgeführt werden.Furthermore, data is recorded and carried out of the method according to the invention take place automatically. There the method according to the invention can run very quickly Checking the critical parameters, preferably not only after switching on a printer, after printing pauses or after Replacing a photoconductor, but also during the Printing operations are carried out at suitable intervals.

Die Erfindung betrifft außerdem eine Anordnung zum Optimieren einer Ladungsbilderzeugung und insbesondere zum Durchführen der erfindungsgemäßen Verfahren. Die oben genannten technischen Wirkungen gelten auch für die Anordnung, die vorzugsweise in einen Drucker oder Kopierer eingebaut ist.The invention also relates to an arrangement for optimization charge image generation and in particular for performing the inventive method. The above technical Effects also apply to the arrangement, which is preferred built into a printer or copier.

Nachfolgend wird die Erfindung unter Bezugnahme auf die anliegenden Zeichnungen erläutert. Darin zeigen:

Figur 1
ein Potential-Zeit-Diagramm unterschiedlicher Kennlinien eines Fotoleiters, und
Figuren 2a, 2b und 2c
jeweils ein Ablaufdiagramm einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens.
The invention is explained below with reference to the accompanying drawings. In it show:
Figure 1
a potential-time diagram of different characteristics of a photoconductor, and
Figures 2a, 2b and 2c
each a flow chart of a preferred embodiment of the method according to the invention.

Figur 1 zeigt ein Potential-Zeit-Diagramm unterschiedlicher Kennlinien K1, K2 eines Fotoleiters, wobei auf einer Ordinate das Potential V des Fotoleiters und auf der Abszisse die Prozeßzeit t aufgetragen sind. Hierbei zeigt ein Zeitpunkt t0 den Beginn des Aufladens eines Fotoleiters auf ein Potential V1 an, das zu einem Zeitpunkt t1 erreicht ist. Zu einem Zeitpunkt t2 kann die Ladung auf dem Fotoleiter aufgrund von Umgebungseinflüssen auf ein Potential V2 abnehmen. Ab dem Zeitpunkt t2 wird der Fotoleiter belichtet. Durch die Belichtung nimmt das auf dem Fotoleiter vorhandene Potential entlang einer Kennlinie K1 oder K2 in einer Zeitspanne von t2 bis t3 auf ein Potential VD1 bzw. VD2 ab. Zum Zeitpunkt t3 beginnt die Entwicklung des Ladungsbildes mittels Toner in der Entwicklerstation. FIG. 1 shows a potential-time diagram of different characteristic curves K1, K2 of a photoconductor, the potential V of the photoconductor being plotted on an ordinate and the process time t on the abscissa. Here, a time t 0 indicates the start of charging a photoconductor to a potential V 1 , which is reached at a time t 1 . At a time t 2 , the charge on the photoconductor can decrease to a potential V 2 due to environmental influences. From time t 2 , the photoconductor is exposed. As a result of the exposure, the potential present on the photoconductor decreases to a potential V D1 or V D2 along a characteristic curve K1 or K2 in a time period from t2 to t3. At time t 3 , the charge image begins to develop using toner in the developer station.

Somit sind auf dem Fotoleiter nach dem Belichten zum Zeitpunkt t3 in Abhängigkeit von Kennlinien K1 oder K2 unterschiedliche Entladepotentiale VD1 bzw. VD2 für den Entwicklungsbeginn vorhanden. Bei den Kennlinien K1 und K2 handelt es sich um beispielhafte Kennlinien, d.h. nach einem Belichten können zum Zeitpunkt t3 auch Bereiche mit anderen, von VD1 oder VD2 abweichenden Potentialen vorhanden sein.Thus, after the exposure at time t 3, different discharge potentials V D1 or V D2 are present on the photoconductor depending on the characteristic curves K1 or K2 for the start of development. The characteristic curves K1 and K2 are exemplary characteristic curves, that is to say, after an exposure, at time t 3 , areas with other potentials that deviate from V D1 or V D2 can also be present.

Der unterschiedliche Verlauf der Kennlinien K1 und K2 eines oder mehrerer Fotleiter hängt beispielsweise von Umgebungsbedingungen, wie der Temperatur, von fertigungsbedingten Schwankungen, von der Qualität des Fotoleiters, von dessen Alter oder von dem aktuellen Prozeßzustand, wie beispielsweise dem Beginn des Druckvorgangs oder der Läge einer Pause zwischen einzelnen Druckvorgängen ab. Hierbei beschreibt die Kennlinie K1 beispielsweise einen Fotoleiter, der relativ unempfindlich und/oder kalt ist. Dagegen beschreibt die Kennlinie K2 einen Fotoleiter, der empfindlicher und/oder wärmer als der durch die Kennlinie K1 beschriebene Fotoleiter ist.The different course of the characteristic curves K1 and K2 or more photoconductors depends on environmental conditions, like the temperature, of manufacturing-related Variations in the quality of the photoconductor and its Age or from the current process status, such as the start of printing or the pause of a pause between individual printing processes. Here describes the Characteristic curve K1, for example, a photoconductor that is relative is insensitive and / or cold. In contrast, the characteristic describes K2 a photoconductor that is more sensitive and / or warmer than the photoconductor described by the characteristic curve K1.

Aus Figur 1 ist ersichtlich, daß in Abhängigkeit von den Kennlinien K1 oder K2 nach dem Belichten unterschiedliche Rest- oder Entladepotentiale VD1 oder VD2 auf dem Fotoleiter verbleiben. Aufgrund dieser Potentialunterschiede zwischen belichteten Bereichen treten Qualtitätsschwankungen im Druckbild auf. Im Idealfall befindet sich dagegen das Potential nach dem Belichten bzw. zum Zeitpunkt t3 auf einem Wert VD soll. Eine Strichlinie zeigt das tiefste erreichbare Entladepotential Vlim.It can be seen from FIG. 1 that, depending on the characteristic curves K1 or K2, different residual or discharge potentials V D1 or V D2 remain on the photoconductor after exposure. Due to these potential differences between exposed areas, quality fluctuations occur in the printed image. In the ideal case, however, the potential is located after the exposure and at the time t 3 to a value V D to. A dashed line shows the lowest achievable discharge potential V lim .

Die Figuren 2a bis 2c sind Ablaufdiagramme einer bevorzugten Durchführung des erfindungsgemaßen Verfahrens. Gemäß Figur 2a wird nach Einschalten einer Druckeinrichtung, nach längeren Pausen oder Störungen der Fotoleiter auf das Standard-Aufladepotential VC s in V (Volt) aufgeladen (Schritt 1a), das mittels einer bekannten Aufladungsregelung konstant gehalten wird. FIGS. 2a to 2c are flow diagrams of a preferred implementation of the method according to the invention. According to FIG. 2a, after switching on a printing device, after longer pauses or faults, the photoconductor is charged to the standard charging potential V C s in V (volts) (step 1a), which is kept constant by means of a known charging control.

Danach wird die Belichtung auf eine Standard-Belichtungsenergie HS in µWs/cm2 eingestellt und der Fotoleiter HS belichtet (Schritt 1b). Ist der Belichtungsvorgang vor oder spätestens zum Zeitpunkt t3 (siehe Figur 1) abgeschlossen, wird das Rest- bzw. Entladepotential VD zum Zeitpunkt t3 gemessen (Schritt 1c). Das Entladepotential VD in V zum Zeitpunkt t3 entspricht beispielsweise einem der Werte VD1 oder VD2 eines Entladepotentials, das in Abhängigkeit von der Kennlinie K1 bzw. K2 eines Fotoleiters als Restpotential auf dem Fotoleiter nach dem Belichten verbleibt (siehe Figur 1).The exposure is then set to a standard exposure energy H S in μWs / cm 2 and the photoconductor H S is exposed (step 1b). If the exposure process is completed before or at the latest at time t 3 (see FIG. 1), the residual or discharge potential V D is measured at time t 3 (step 1c). The discharge potential V D in V at time t 3 corresponds, for example, to one of the values V D1 or V D2 of a discharge potential which, depending on the characteristic curve K1 or K2 of a photoconductor, remains as a residual potential on the photoconductor after exposure (see FIG. 1).

Anschließend wird die Temperatur T des Fotoleiters in Schritt 2 gemessen. Die Temperatur kann jedoch auch zu einem späteren oder früheren Zeitpunkt gemessen werden.Then the temperature T of the photoconductor in step 2 measured. However, the temperature can also be increased to a later one or earlier.

Anschließend werden zuerst ein Empfindlichkeitsfaktor K und auf der Basis des Empfindlichkeitsfaktors K eine angepaßte Belichtungsenergie Ha in µWs/cm2 berechnet (Schritt 3). Der Empfindlichkeitsfaktor K kann beispielsweise in Abhängigkeit von dem momentanen Aufladepotential VC, der Temperatur T, der momentanen Belichtungsenergie H, dem gemessenen Entladepotential VD und einem tiefsten erreichbaren Entladepotential Vlim mithilfe der Gleichung (1) berechnet werden als:

Figure 00120001
Subsequently, a sensitivity factor K and, based on the sensitivity factor K, an adapted exposure energy H a in μWs / cm 2 are calculated (step 3). The sensitivity factor K can be calculated, for example, as a function of the instantaneous charging potential V C , the temperature T, the instantaneous exposure energy H, the measured discharging potential V D and a lowest achievable discharging potential V lim as:
Figure 00120001

Dabei kann anstelle der Temperatur T auch ein aus dieser ermittelter Temperaturfaktor TF verwendet werden, der den Einfluß der Temperatur auf den Empfindlichkeitsfaktor K genauer angibt.Instead of the temperature T, this can also be used determined temperature factor TF can be used, the Influence of temperature on sensitivity factor K more precisely indicates.

Eine angepaßte Belichtungsenergie Ha wird dann vorzugsweise mithilfe von Gleichung (2) auf der Basis des Empfindlichkeitsfaktors K berechnet als:

Figure 00130001
wobei VD soll der Zielwert für das Entladepotential VD ist.An adapted exposure energy H a is then preferably calculated using equation (2) on the basis of the sensitivity factor K as:
Figure 00130001
where V D is the target value for the discharge potential V D.

In dem anschließenden Schritt 4 wird geprüft, ob die in Schritt 3 angepaßte Belichtungsenergie Ha kleiner als die maximale oder größer als die minimale, mit der verwendeten bzw. vorhandenen Belichtungseinheit einstellbare Belichtungsenergie Hmax bzw Hmin oder gleich einem dieser Grenzwerte ist. Liegt Ha außerhalb dieses Bereichs, so werden die später anhand von Figuren 2b und 2c beschriebenen Schritte durchgeführt.In the subsequent step 4, it is checked whether the exposure energy H a adjusted in step 3 is less than the maximum or greater than the minimum exposure energy H max or H min that can be set with the used or available exposure unit or is equal to one of these limit values. Is H a outside this range, then the later with reference to figures 2b and 2c performed steps.

Liegt die angepaßte Belichtungsenergie Ha im Intervall Hmin ≤ Ha ≤ Hmax, so wird in einem Schritt 5a analog dem Schritt 1a der Fotoleiter erneut auf das Standard-Aufladepotential VC s aufgeladen. Nach Abschluß des Aufladevorgangs wird der Fotoleiter mit der berechneten angepaßten Belichtungsenergie Ha belichtet (Schritt 5b'). Danach wird das auf dem Fotoleiter erzeugte Entladepotential VD gemessen.If the adjusted exposure energy H a lies in the interval H min H H a H H max , the photoconductor is recharged to the standard charging potential V C s in a step 5a analogous to step 1a. After completion of the charging of the photoconductor is matched with the calculated exposure energy H a exposed (step 5b '). Then the discharge potential V D generated on the photoconductor is measured.

Hierauf wird in Schritt 6 das in Schritt 5c gemessene Entladepotential VD mit dem Soll-Potential VD soll vergleichen (siehe Figur 1).Then, in step 6, the measured in step 5c discharge potential V D with the desired potential V D to compare (see Figure 1).

Liegt das erzeugte Entladepotential VD innerhalb eines vorgegebenen Toleranzbereichs, d.h. weicht das erzeugte Entladepotential VD nur geringfügig von dem Soll-Potential VD soll ab, so wird im Anschluß hieran ein Ladungsbild erzeugt (Schritt 7), indem der Fotoleiter auf das Standard-Aufladepotential VC s geladen und anschließend mit der angepaßten Belichtungsenergie Ha belichtet wird.Is the discharge potential generated V D within a predetermined tolerance range, that is the discharge potential generated V D differs only slightly from the desired potential V D to off, a charge image is subsequently thereto (step 7) by the photoconductor to the standard Charging potential V C s is loaded and then exposed with the adapted exposure energy H a .

Liegt das beim Schritt 5c erzeugte Entladepotential VD nicht innerhalb des vorgegebenen Toleranzbereichs, so ist ein Iterationszyklus mit dem in Schritt 5c gemessenen Entladepotential VD und der in Schritt 3 berechneten, angepaßten Belichtungsenergie Ha erforderlich, bei welchem die Schritte 2 bis 6 erneut durchgeführt werden.If the discharge potential V D generated in step 5c is not within the predetermined tolerance range, then an iteration cycle with the discharge potential V D measured in step 5c and the adjusted exposure energy H a calculated in step 3 is required, in which steps 2 to 6 are carried out again become.

Die vorstehend beschriebene Iterationsschleife, in der die Schritte 2 bis 6 durchgeführt werden, wird so oft wiederholt, bis das erzeugte Entladepotential VD innerhalb des Toleranzbereichs liegt und der Schritt 7 durchgeführt werden kann; d.h. ein Ladungsbild durch Aufladen des Fotoleiters auf das Standard-Auflade-Potential VC S und Belichten mit der entsprechend angepaßten Belichtungsenergie Ha erzeugt wird.The iteration loop described above, in which steps 2 to 6 are carried out, is repeated until the generated discharge potential V D is within the tolerance range and step 7 can be carried out; ie a charge image is generated by charging the photoconductor to the standard charging potential V C S and exposing it with the appropriately adapted exposure energy H a .

Ist jedoch bei einer der Iterationen die Entscheidung in Schritt 4 "nein", werden die anhand der Figuren 2b und 2c nachstehend beschriebenen Schritte durchgeführt.However, in one of the iterations, the decision is in Step 4 "no" are those based on FIGS. 2b and 2c steps described below.

Gemäß des in Figur 2b dargestellten Teils des Ablaufdiagramms des erfindungsgemäßen Verfahrens wird in einem Schritt 4' entscheiden, ob die - in Schritt 3 (siehe Figur 2a) berechnete - angepaßte Belichtungsenergie Ha größer als eine maximal zulässige Belichtungsenergie Hmax ist. Ist die in Schritt 4' getroffene Entscheidung "nein", d.h. ist die angepaßte Belichtungsenergie kleiner als eine minimal zulässige Belichtungsenergie Hmin, so wird der später anhand von Figur 2c beschriebene Teil des Ablaufdiagramms durchgeführt.According to the part of the flowchart of the method according to the invention shown in FIG. 2b, a step 4 'will decide whether the adjusted exposure energy H a calculated in step 3 (see FIG. 2 a) is greater than a maximum permissible exposure energy H max . If the decision made in step 4 'is "no", ie if the adjusted exposure energy is less than a minimum permissible exposure energy H min , the part of the flowchart described later with reference to FIG. 2c is carried out.

Ist die angepaßte Belichtungsenergie Ha größer als die maximale Belichtungsenergie Hmax, so lautet die Entscheidung "ja" und der Fotoleiter wird in Schritt 8a entsprechend dem Schritt 1a auf das Standard-Aufladepotential VC s aufgeladen und im Unterschied zu den Schritten 1b und 5b' anschließend mit maximaler Belichtungsenergie Hmax belichtet (Schritt 8b''). Danach wird das auf dem Fotoleiter erzeugte Entladepotential VD bestimmt (Schritt 8c). If the adjusted exposure energy H a is greater than the maximum exposure energy H max , the decision is "yes" and the photoconductor is charged in step 8a according to step 1a to the standard charging potential V C s and in contrast to steps 1b and 5b 'then exposed with maximum exposure energy H max (step 8b''). The discharge potential V D generated on the photoconductor is then determined (step 8c).

Hierauf wird beim Schritt 9 ein angepaßtes Aufladepotential VC a ermittelt, das beispielsweise entweder gemäß Gleichung (3)

Figure 00150001
oder gemäß Gleichung (4)
Figure 00150002
berechnet werden kann. In den Gleichungen (3) oder (4) wird der anhand der Gleichung (1) berechnete momentane Empfindlichkeitsfaktor K verwendet.In step 9, an adapted charging potential V C a is then determined, which, for example, either according to equation (3)
Figure 00150001
or according to equation (4)
Figure 00150002
can be calculated. The instantaneous sensitivity factor K calculated using equation (1) is used in equations (3) or (4).

In Schritt 10 wird entschieden, ob das angepaßte Aufladepotential VC a innerhalb eines Arbeitsbereiches liegt oder nicht.In step 10, a decision is made as to whether the adjusted charging potential V C a is within a working range or not.

Ist die Entscheidung in Schritt 10 "ja", wird der Fotoleiter mit dem in Schritt 9 berechneten, angepaßten Aufladepotential VC a aufgeladen (Schritt 11a'), anschließend mit maximaler Belichtungsenergie Hmax belichtet (Schritt 11b') und in Schritt 11c das Entladepotential VD bestimmt.If the decision in step 10 is "yes", the photoconductor is charged with the adapted charging potential V C a calculated in step 9 (step 11a '), then exposed with maximum exposure energy H max (step 11b') and in step 11c the discharge potential V D determined.

Anschließend wird in Schritt 12 analog zu Schritt 6 untersucht, ob das Entladepotential VD innerhalb eines vorgegebenen Toleranzbereichs liegt. Ist dies der Fall, so wird das Ladungsbild mit dem angepaßten Aufladepotential VC a und durch ein Belichten mit maximaler Belichtungsenergie Hmax erzeugt (Schritt 13).Then, in step 12, analogously to step 6, it is examined whether the discharge potential V D is within a predetermined tolerance range. If this is the case, the charge image is generated with the adapted charging potential V C a and by exposure with maximum exposure energy H max (step 13).

Ist jedoch bereits beim ersten Durchgang oder nach Durchlaufen einer oder mehrerer Iterationsschleifen (Schritte 9 bis 12) die Entscheidung beim Schritt 10 "nein", so wird der Fotoleiter mit einem minimalen Aufladepotential VC min aufgeladen und anschließend mit maximaler Belichtungsenergie Hmax belichtet (Schritt 14).If, however, the decision in step 10 is "no" already on the first pass or after passing through one or more iteration loops (steps 9 to 12), the photoconductor is charged with a minimal charging potential V C min and then exposed with maximum exposure energy H max (step 14).

Das in Figur 2c dargestellte Ablaufdiagramm wird durchge-führt, wenn die in Schritt 4' (Figur 2b) getroffene Entscheidung "nein" ist, d.h. die in Schritt 3 (Figur 2a) berechnete angepaßte Belichtungsenergie Ha kleiner als die minimale Belichtungsenergie Hmin ist.The flow chart shown in FIG. 2c is carried out when the decision made in step 4 '(FIG. 2b) is "no", ie the adjusted exposure energy H a calculated in step 3 (FIG. 2a) is less than the minimum exposure energy H min ,

Wie aus Figur 2c ersichtlich ist, werden mit Ausnahme der Schritte 8b''', 9', 11b'', 13' und 14' die bereits in Figur 2b dargestellten Schritte 8a bis 13 durchgeführt. In Schritt 8b''' wird der Fotoleiter im Unterschied zu Schritt 8b'' in Figur 2b nicht mit maximaler, sondern mit minimaler Belichtungsenergie Hmin belichtet. Lautet das Ergebnis der Entscheidung in Schritt 10 "nein", so wird in dem in Figur 2c dargestellten Teil des Ablaufdiagramms der Schritt 14' durchgeführt, in welchem ein Ladungsbild auf dem auf maximales Aufladepotential VC max aufgeladenen Fotoleiter mittels minimaler Belichtungsenergie Hmin erzeugt wird.As can be seen from FIG. 2c, with the exception of steps 8b ''',9', 11b '', 13 'and 14', steps 8a to 13 already shown in FIG. 2b are carried out. In step 8b ''', in contrast to step 8b''in FIG. 2b, the photoconductor is not exposed with maximum, but with minimum exposure energy H min . If the result of the decision in step 10 is "no", step 14 'is carried out in the part of the flowchart shown in FIG. 2c, in which a charge image is generated on the photoconductor charged to maximum charging potential V C max by means of minimal exposure energy H min ,

Ein weiterer Unterschied zwischen dem in Figur 2b ab dem Schritt 8a dargestellten Teil und dem in Figur 2c dargestellten Teil besteht in der in Schritt 9' verwendeten Gleichung (3). Analog zu dem vorstehend beschriebenen Unterschied der beiden Teile in den Schritten 8b''', 11b'', 13' und 14', in denen anstelle der maximalen eine minimale Belichtungsenergie Hmin verwendet wird, muß anstelle der beim Schritt 9 zur Berechnung des angepaßten Aufladepotentials VC a verwendeten Gleichung (3) die Gleichung (3') verwendet werden, in welcher Hmax durch Hmin ersetzt ist, Gleichung (3') lautet daher folgendermaßen:

Figure 00160001
Another difference between the part shown in FIG. 2b from step 8a and the part shown in FIG. 2c is the equation (3) used in step 9 '. Analogous to the above-described difference between the two parts in steps 8b ''',11b'',13' and 14 ', in which a minimum exposure energy H min is used instead of the maximum, instead of that in step 9, the adjusted must be calculated '(equation 3) is used, max in which H replaced by H min, equation charging potential V C a used (3) equation (3)', therefore, is as follows:
Figure 00160001

Das es sich hierbei um eine Bilderzeugung mit fest vorgegebenen und nicht mittels des erfindungsgemäßen Optimierungsverfahrens bestimmten Werten handelt, kann eine entsprechend Anzeige aktiviert werden, um den Benutzer darauf hinzuweisen, daß die Kopier- oder Druckeinrichtung nicht unter optimalen Betriebsbedingungen arbeitet.That this is an image generation with fixed default and not by means of the optimization method according to the invention certain values can be dealt with accordingly Be activated to notify the user that the copying or printing device is not under optimal Operating conditions works.

Claims (20)

  1. Method for optimizing a charge image generation on a photoconductor of an electrophotographic printer or copier device, wherein
    a) the photoconductor is charged to a predetermined charging potential (VC) (step 1a),
    b) the charged photoconductor is exposed with a predetermined exposure energy (H) and is thereby discharged (step 1b),
    c) the discharge potential (VD) of the exposed photoconductor is determined (step 1c),
    d) and wherein the temperature (T) of the photoconductor is determined (step 2)
    characterized in that
    e) a sensitivity factor (K) is determined from the charging potential (VC), the exposure energy (H), the discharge potential (VD) and the temperature (T), said sensitivity factor (K) defining the relationship between the discharge potential (VD) and the exposure energy (H) in a predetermined relationship between the discharge potential (VD) and the exposure energy (H) given a fixed temperature (T) (step 3),
    f) a new exposure energy (H) that is employed instead of the previous exposure energy is determined from the charging potential (VC), the temperature (T), the identified sensitivity factor (K) and a predetermined desired value (VD soll) for the discharge potential (VD) according to the given relationship converted to the exposure energy (H) (step 3),
    g) and in that a charge image is generated with the determined exposure energy (H) and the predetermined charging potential (VC) (step 7).
  2. Method according to claim 1, characterized in that the sensitivity factor (K) is determined according to the equation:
    Figure 00280001
    wherein
    K
    is the sensitivity factor,
    TF
    is a temperature factor determined from the temperature T,
    H
    is the exposure energy in µWs/cm2
    VC
    is the charging potential in V,
    VD
    is the discharge potential in V, and
    Vlim
    is the lowest obtainable discharge potential in V.
  3. Method according to claim 1 or 2, characterized in that the new exposure energy (H) is determined according to the equation:
    Figure 00280002
    wherein
    H
    is the exposure energy,
    TF
    is a temperature factor determined from the temperature,
    K
    is the sensitivity factor,
    VC
    is the charging potential in V
    VD soll
    is the desired value of the discharge potential in V, and
    Vlim
    is the lowest obtainable discharge potential in V.
  4. Method according to one of the preceding claims, characterized in that the following steps are implemented following the step f) according to claim 1:
    f1) after the renewed exposure of the photoconductor charged with the predetermined charging potential (VC) with the most recently determined exposure energy (H), the discharge potential (VD) on the photoconductor is identified anew and employed instead of the previous discharge potential (VD) (steps 5a, 5b', 5c),
    f2) when the discharge potential (VD) lies within a predetermined tolerance range, the step g) according to claim 1 is implemented (step 6),
    f3) when the discharge potential (VD) does not lie within the tolerance range, the steps d) to f3) or e) to f3) are repeated until the discharge potential (VD) lies within the tolerance range (step 6).
  5. Method according to one of the preceding claims, characterized in that a desired value for the difference of the charging potential (VC) and the discharge potential (VD) is employed instead of the desired value (VD soll) for the discharge potential (VD).
  6. Method for optimising a charge image generation on a photoconductor of an electrophotographic printer or copier device, wherein
    A) the photoconductor is charged to a predetermined charging potential (VC) (step 8a),
    B) the charged photoconductor is exposed with a predetermined exposure energy (H) and is thereby discharged (step 8b"; 8b"'),
    C) the discharge potential (VD) of the exposed photoconductor is determined (step 8c),
    D) and wherein the temperature (T) of the photoconductor is determined (step 2),
    characterized in that
    E) a sensitivity factor (K) is determined from the charging potential (VC), the exposure energy (H), the discharge potential (VD) and the temperature (T), said sensitivity factor (K) defining the relationship between the discharge potential (VD) and the exposure energy (H) in a predetermined relationship between the discharge potential (VD) and the exposure energy (H) given a fixed temperature (T) (step 9; 9'),
    F) a new charging potential (VC) that is employed instead of the previous charging potential (VC) is determined from the exposure energy (H), the temperature (T), the identified sensitivity factor (K) and a predetermined desired value (VD soll) for the discharge potential (VD) according to the given relationship converted to the charging potential (VC) (step 9; 9'),
    G) and in that a charge image is generated with the determined charging potential (VC) and the predetermined exposure energy (H) (step 13; 13').
  7. Method according to claim 6, characterized in that the sensitivity factor (K) is determined according to the equation:
    Figure 00300001
    wherein
    K
    is the sensitivity factor,
    TF
    is a temperature factor determined from the temperature T,
    H
    is the exposure energy in µWs/cm2
    VC
    is the charging potential in V,
    VD
    is the discharge potential in V, and
    Vlim
    is the lowest obtainable discharge potential in V.
  8. Method according to claim 6 or 7, characterized in that the new charging potential (VC) is determined according to the equation: VC = (VD soll - Vlim) · exp(K·TF·H) + Vlim wherein
    VC
    is the charging potential,
    VD soll
    is the discharge potential in V,
    Vlim
    is the lowest obtainable discharge potential in V,
    TF
    is a temperature factor determined from the temperature T,
    K
    is the sensitivity factor and
    H
    is the exposure energy in µWs/cm2.
  9. Method according to one of the claims 6 to 8, characterized in that a desired value for the difference of the charging potential (VC) and the discharge potential (VD) is employed instead of the desired value (VD soll) for the discharge potential (VD).
  10. Method according to one of the claims 6 to 9, characterized in that the following steps are implemented following the step F):
    F1) after the renewed exposure of the photoconductor charged with the predetermined charging potential (VC) with the predetermined exposure energy (H), the discharge potential (VD) on the photoconductor is identified anew and employed instead of the previous discharge potential (VD) (steps 11a, 11b', 11c; 11a', 11b", 11c),
    F2) when the discharge potential (VD) lies within a predetermined tolerance range, the step G) according to claim 6 is implemented (step 12),
    F3) when the discharge potential (VD) does not lie within the tolerance range, the steps D) to F3) or E) to F3) are repeated until the discharge potential (VD) lies within the tolerance range (step 12).
  11. Method according to claim 10, characterized in that, before the implementation of the step F1), a check is carried out to see whether the determined charging potential (VC) lies in a predetermined working range (step 10),
    the step F1) is only implemented when the determined charging potential (VC) lies within the working range,
    and in that, instead of the steps F1) to F3) a charge image is generated with the predetermined exposure energy (H) and with a predetermined charging potential (VC) that preferably lies at a limit of the working range when the identified charging potential (VC) lies outside the working range (step 14; 14').
  12. Method according to one of the claims 6 to 10, characterized in that, before the implementation of said steps, a determination is made that an exposure energy (H) determined for a predetermined charging potential (VC) lies above a maximum exposure energy (Hmax) (steps 4; 4'),
    and in that the predetermined exposure energy (H) has the value of the maximum exposure energy (Hmax).
  13. Method according to one of the claims 6 to 11, characterized in that, before the implementation of said steps, a determination is made that an exposure energy (H) determined for a predetermined charging potential (VC) lies below a minimum exposure energy (Hmin) (steps 4, 4'),
    and in that the predetermined exposure energy (H) has the value of the minimum exposure energy (Hmin).
  14. Method according to one of the preceding claims, characterized in that the charging potential (VC) is determined according to the equation:
    Figure 00320001
    wherein
    VC
    is the charging potential,
    VD
    is the discharge potential in V,
    K
    is the sensitivity factor,
    TF
    is a temperature factor determined from the temperature T,
    H
    is the exposure energy in µWs/cm2, and
    Vlim
    is the lowest obtainable discharge potential in V.
  15. Method according to one of the preceding claims, characterized in that a temperature factor (TF) is determined from the temperature (T) according to the following equation: TF = a+b · T +c ·T2, wherein T is the temperature in degrees Celsius, and wherein a, b and c are fixed coefficients.
  16. Method according to one of the preceding claims, characterized in that, for accelerating the implementation of the method, ailocafion tables are produced proceeding from the predetermined relationship and/or the converted relationship.
  17. Method according to one of the preceding claims, characterized in that, for accelerating the implementation of the method, allocation tables are empirically produced printer-specific.
  18. Method according to one of the preceding claims, characterized in that it is implemented after turn-on, after printing pauses, after replacement of the photoconductor and/or at predetermined time intervals during printing operation.
  19. Arrangement for optimizing a charge image generation and, in particular, for the implementation of the method according to one of the preceding claims,
    comprising a light-sensitive layer system,
    a charging device for generating a charging potential (VC) on the light-sensitive layer system,
    an exposure means for the exposure of the charged layer system with an exposure energy (H),
    a temperature sensor for acquiring the temperature (T) of the layer system,
    a potential sensor for acquiring the discharge potential (VD) on the light-sensitive layer system after the exposure,
    and comprising a control unit for the predetermination of the charging potential (VC) and the exposure energy (H),
    characterized in that, in the prescription of the charging potential (VC) and/or of the exposure energy (H), the control unit determines a sensitivity factor (K) that defines the relationship between the discharge potential (VD) and the exposure energy (H) in a predetermined relationship between the discharge potential (VD) and the exposure energy (H) given a fixed temperature (T).
  20. Printer, characterized in that it contains the arrangement according to claim 19.
EP97920571A 1996-03-29 1997-03-27 Process and arrangement for optimising charge pattern formation on a photoconductor Expired - Lifetime EP0888579B1 (en)

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DE59710268D1 (en) 2003-07-17
WO1997037285A1 (en) 1997-10-09
EP0888579A1 (en) 1999-01-07
US6167210A (en) 2000-12-26

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