EP1156380A2 - Electrophotographic process control and diagnostic system - Google Patents

Abstract

Method has the following steps: determination of the charging efficiency between a first charging station (28) and a photo-conducting element (18), generation of a reference voltage on the photo-conducting element corresponding to the charging efficiency, non-printing operation of a first sub-system to generate a first resulting voltage on the photo-conducting element and movement of the element to a fixed sensor (50) to measure the resultant voltage. An Independent claim is made for a an electro-graphic marking apparatus with a voltage meter (50) and a logical control unit (24).

Description

The present invention relates to electrophotographic marking apparatus, in particular testing subsystems of the electrophotographic process and creating Setting operations for certain subsystems in relation to predetermined ones Parameters.

The electrophotographic marking process is relatively complicated and involves one Variety of subsystems, each of which must work properly. This one Subsystems are interconnected, however, it is often difficult to function as one diagnose and isolate specific subsystem. This is especially true for electrophotographic imaging and image development processes as an investigation in the case of room lighting with the naked eye is mostly impossible.

Therefore, there is a need for analysis and diagnostic testing of one electrophotographic process in which certain subsystems with satisfactory Operating parameters can be compared and suitable remedial measures can be taken. The object of the present invention is therefore an analysis and diagnostic To create test method with which certain subsystems with satisfactory Operating parameters can be compared and suitable remedial measures can be taken.

This is according to the invention with a method having the features of claims 1 and a device with the features of claim 13 solved. Other characteristics result itself from the subclaims.

The present invention provides optional electrophotographic control Marking apparatus that enables a functional test of the subsystems. In a Another embodiment, the invention provides an automatic Subsystem function test ready and thus complements subsystem-specific diagnostics and review programs.

The present invention provides a reference voltage on a photoconductor element, such as. a ribbon, the ribbon being at a predetermined in non-printing operation Subsystem is passed, the resulting voltage measured and with predetermined acceptable limits are compared. Then there is one Regeneration cycle provided so that the electrophotographic marker is on Printing operation can be made.

The invention is more preferred below with reference to the drawings Embodiments described.

Fig. 1

eine schematische Seitenansicht eines typischen elektrofotografischen Markierungsapparats, auf den die vorliegende Erfindung anwendbar ist.

Fig. 2

ein Blockdiagramm einer Logik- und Steuereinheit von Fig. 1.

Fig. 3

ein Flussdiagramm eines Teils der Vorgänge, die von der Logik- und Steuereinheit ausgeführt werden.

The drawings show:

Fig. 1

is a schematic side view of a typical electrophotographic marking apparatus to which the present invention is applicable.

Fig. 2

2 shows a block diagram of a logic and control unit from FIG. 1.

Fig. 3

a flowchart of part of the operations performed by the logic and control unit.

An electrographic marking apparatus 10 is shown in FIG. 1. The present Invention is based on a special electrographic marking apparatus 10, such as e.g. a copier or printer. Still, it should be noted that, though the invention is suitable for use in such apparatus, but also with other types can be used by electrophotographic copiers and printers.

Since electrophotographic markers of the type described herein are known this description focuses in particular on the elements that are part of the present invention or are directly related to it.

V₀ = Haupt/Primärspannung (relativ zur Erdung) auf dem Fotoleiter, wie sie direkt nach der ersten Ladeeinrichtung gemessen wird. Sie wird manchmal auch als "Anfangsspannung" bezeichnet.

V_0(m) = Mittelwert der einzelnen V₀ Werte.

V_B = Elektrodenvorspannung der Entwicklereinheit.

To facilitate understanding, the following definitions are established:

V ₀ = main / primary voltage (relative to ground) on the photoconductor as measured directly after the first charging device. It is sometimes referred to as the "initial tension".

V _{0 (m)} = mean value of the individual V ₀ values.

V _B = electrode bias of the developer unit.

In the electrophotographic marking apparatus 10 shown in FIG. 1 there is a movable image bearing element, e.g. a photoconductive tape 18 around a variety of Tensioned rollers, one of which is driven by a motor, pass the belt at a number of processing stations of the printer. The image carrier element can also be designed as a drum. The logic and control unit (LCU) 24 which can include a digital computer, assigns a stored program successive actuation of the different processing stations or subordinate systems of the apparatus 10.

A charging station makes the belt 18 photosensitive by applying a uniform electrostatic charge of a predetermined primary voltage V ₀ to the surface of the belt. The power of the first charging station is regulated by a programmable controlled power supply 30, which in turn is controlled by the LCU 24 in order to set the primary voltage V _0, for example by controlling the electrical potential (V _Grid ) on a grid electrode 28b, which controls the movement of the charged ions that is caused by the operation of the charging wires 28a on the surface of the support member. In the present example, a negative electrical bias is present at the grid electrodes 28b, for example between -350 and -750 volts; a target bias can be -500 volts.

At an exposure station, the projected light from a write head 34 modulates the electrical charge on the photoconductive belt 18 to form a latent electrostatic image to generate a document to be copied or printed. The print head points preferably a series of light emitting diodes (LEDs) or another Light source, e.g. a laser or other exposure source to expose the photoconductive tape. The exposure takes place picture element (pixel) for picture element with a regulated in accordance with the signals from the LCU to the write head interface 32 Intensity, the write head interface being a programmable control unit includes. Alternatively, the exposure can be carried out by optical projection of an image of a Document made on the photoconductor 18.

If an LED or other electro-optical exposure source is used, the image data to be recorded from a data source 36 for generating electrical Image signals, e.g. from a computer, a document scanner, a memory or a data network. Signals from the data source and / or LCU can also output control signals to a writer network, etc.

The movement of the belt 18 in the direction of the arrow A leads the areas that carry the latent electrostatographic charge images past a developer station 38. The toner or developer unit has one or more (several with different colors) magnetic brushes next to, but at a distance from the belt.
Magnetic brush developer units are known from US 4,473,029 and 4,546,060.

The LCU 24 optionally operates the developer unit in relation to the areas of the image gliding past that carry the latent images. The Magnetic brush either in contact with or at a short distance from belt 18 brought. The charged toner particles of the contacted magnetic brush are called Image is drawn onto the latent image pattern to develop the pattern. In doing so also developed the calibration marks used for process control.

As is known from the prior art, the conductive parts of the developer unit, such as conductive application cylinders, act as electrodes. The electrodes are connected to a variable supply of DC potential V _B , which is regulated by a programmable controller 40. The details regarding the developer units are set out using an example, but are not essential to the invention.

In this example, the development corresponds to a DAD process (DAD = development of the discharged area), in which negatively charged toner particles alternatively in relative Develop discharged areas of the light guide element. Other types of Developer units are known and can also be used.

A transmission unit 46, as is also known, is provided to transmit one Recording sheet S in register with the image in contact with the light-guiding element bring. In this way the image is placed on a recording sheet, e.g. made of paper, or transfer a plastic sheet. Alternatively, the image can first be on an intermediate element and then transferred to the recording sheet. In the embodiment in FIG. 1 the transmission unit comprises a transmission corona charger 47.

The toner image is transferred electrostatically with a suitable voltage, which is applied to the transfer charger 47 to supply a constant current generate as described below. The back of the receiver sheet is in this Example charged with a positive charge by the transfer charging device, contacts the toner image on the photoconductor element during the recording sheet in order to Drag the toner image onto the recording sheet.

After the transfer, the recording sheet can be made using a known (not )) non-stick corona charger can be released from the belt 18. A Cleaning brush 48 or a knife is also arranged downstream of the transmission unit provided to remove the toner from the belt 18 so as to be reusable the surface for forming additional images is made possible. To remove Lightening the toner residue and other particles from the brush 48 is common a charging device 43 is provided, in this case positive charge on the Neutralize light guide element or the electrostatic adhesion of the remaining particles to reduce the volume 18. The tension of cleaning and Preparation charger is controlled by a power supply 42. While separate power supplies for each charger can be shown, one Power supply with several supply lines instead of several Power supply devices are used.

After transferring the unfixed toner images to a recording sheet, the Receiving sheet transported to a melting unit 49, on which the image is fixed.

A densitometer 76 is between the developer unit 38 and the transfer unit 46 arranged. The densitometer 76 monitors the development of the areas of the light-conductive tape 18, as is known from the prior art.

A second sensor, which is also preferably provided for process control, is an electrostatic voltage meter 50. A voltage meter is preferably located downstream of the first charging station 28 in order to provide readings of measured V ₀ s or V _{0 (m)} s. The voltmeter is preferably fixed in relation to the band 18, thus reducing problems with the alignment and settings associated with the portable voltmeter, particularly with respect to the band 18. The voltmeter (electrometer) 18 can handle both polarities of the voltage measure and is therefore used to determine all voltage tests.

The output V _{0 (m)} s and densities, which the densitometer 76 determines, are fed to the LCU 24, which generates new setpoints for E ₀ , V ₀ , V ₀ and the actuation of the toner replenishment in accordance with a process control program. In addition, the process controller can be used to adjust the transmission current generated by the transfer charger 46 by changing the programmable power supply 51. A preferred electrometer is described in US 5,956,544.

The apparatus 24 can be defined as a variety of subsystems including but not limited to, the general descriptions of a cargo system, one Exposure unit, a developer subsystem, a transmission subsystem, one Post-treatment subsystem, a meltdown subsystem, these subsystems the components described above, e.g. the photoconductor, the first charging station, the bias shift, the post-treatment charging station and the transfer rollers include.

In addition, the LCU 24 provides overall control of the device and its different child systems. Programming commercially available Microprocessors are familiar to the person skilled in the art. The following revelation aims to enable a programmer to create a suitable control program for to write such a microprocessor.

The logical links described in this document can be left out of microprocessors also from or in cooperation with non-programmable (hardware) or programmable logic devices can be created. To the precisely control the timing of the various processing facilities, are usually encoders in conjunction with indicators on the photoconductor used to provide timely signals indicating the frame areas and their position show in relation to the different units. Other types of control for timing of operations can also be used.

2 shows a block diagram of a typical LCU 24. The typical LCU 24 includes a temporary data memory 152, the central processing unit 154, the process and event check module 155, timing and cycle control unit 156 and the stored program control 158. The data input and output takes place sequentially based on or under the supervision of the program control.

Input data is either stored in one by the input signal latch 160 Input data processor 162 fed or by an interrupt signal processor 164. The input signals are from various switches, sensors and analog-to-digital Transducers that are part of the apparatus 10 derived or from external sources passed it on. The output data and control signals are immediately or fed into suitable output drivers 168 by a catch register 166. The Output drivers are connected to the appropriate subordinate systems.

The LCU 24 is set up to perform a series of subsystem tests performs. By performing these tests, the LCU 24 ensures the normal Printing operation of the apparatus 10. In addition, the LCU 24 is set so that the Operates apparatus in test mode, whereby the entire photoelectric process is carried out becomes.

In the present test (non-printing) operation, the LCU 24 is generally like this set to generate a predetermined tension on the belt 18 and subsequently selects a specific subsystem, the subsystem selecting one corresponding deviation in the belt tension generated. The LCU 24 causes one Rotation of the belt 18 to the voltmeter 50, where the resulting belt tension is measured. The measured voltage is determined by the LCU 24 with a predetermined one Compare a range of allowable values. In addition, the deviation is reported to the engineer passed on site when the measured voltage is outside the predetermined Frame.

The LCU 24 is also set so that the non-tested subsystems are isolated to reduce the risk of damage to certain subsystems.

The LCU 24 also includes regeneration operations that each of the Subsystem check operations correspond. The regeneration processes can the apparatus 10 return to normal printing. Optionally, the Regeneration operations the apparatus 10 for testing additional subsystems to prepare. 3 is a flowchart of the process and process check program of FIG LCU 24 shown.

More specifically, the LCU 24 measures a voltage of the first charging station and stores one resulting voltage on the photoconductor element, as at the electrometer 50 was measured. The voltage of the photoconductor element is measured with the voltage compared to determine charge efficiency. As from the state of the art is known, an increase in charge efficiency shows an increased contamination in the first charging station. The exit test / first test thus enables one On-site engineer to check the functionality of the first charging station.

wobei

die anhand der bei der Prüfung der ersten Ladestation erhaltenen Werte bestimmte Ladungseffizienz ist. Die LCU sorgt somit dafür, dass jede Prüfung auf eine bekannte und bestimmte Referenzspannung standardisiert ist.Since the performance of some subsystems is measured by their effect on the photoconductor _voltage , it is desirable to _apply a film reference _voltage V _0ref to the photoconductor before testing the subsystems. The reference voltage is achieved by setting the grid voltage of the first charging station as follows:

in which

is the charge efficiency determined from the values obtained when testing the first charging station. The LCU thus ensures that every test is standardized to a known and specific reference voltage.

The electrophotographic marking apparatus 10 is not in the printing mode and the reference voltage V ₀ is transferred to the tape 18. A particular subassembly is then switched which creates a voltage on the photoconductive belt 18 or transmits it to the belt 18. The LCU 24 then sets the tape 18 in rotation along its path so that the resulting tension on the tape is measured on the electrometer 50. That is, the LCU 24 ensures that the resulting voltage is brought to the electrometer 50 instead of moving the electrometer to the resulting voltage.

The resulting voltage of the photoconductive element 18 is then measured with a predetermined set of acceptable voltages compared to establish criteria who decide on the further process.

In addition, the operator is aware of the deviation of the measured voltage from the certain subsystem made accessible so that predictions about its lifespan can be employed.

A. Haupantriebsprüfung - Diese Prüfung überprüft Hauptzeitgebung, Übergangsstellendetektion und die Filmspur für den Markierungsapparat.

B. Automatische Set-Up Phase I- In der ersten Phase der automatischen Set-up Prüfung werden das Densitometer und das Fotoleitelement überprüft. Dann erfolgt eine Analyse des Verunreinigungsgrades.

C. Automatische Set-Up Phase II - In der zweiten Phase der automatischen Set-Up Prüfung werden das Laden und die Kalibrierung des Elektrometers sowie der Vorspannungsoffset überprüft.

D. Automatische Set-Up Phase III - In der dritten Phase der automatischen Set-Up Prüfung werden die Prozesssteuerung und die Sollwerte des Elektrofotografen überprüft.

E. Automatische Set-Up Phase IV - In der vierten Phase der automatischen Set-Up Prüfung werden der Belichtungsgrad und die Spannung des fotoleitenden Elements überprüft.

F. Erste Ladestation - Die erste Ladestation überprüft den Verunreinigungsgrad der ersten Ladestation und sorgt für eine Übereinstimmung mit den vorbestimmten Sollwerten.

G. Vor-Reinigungsladestation - Diese Prüfung überprüft den Film für das Reinigen nach der Übertragung und vor der Reinigung.

H. Nachbehandlungsladestation - Das Nachbehandlungsladestationsprogramm sorgt für die Prüfung der Nachbehandlungsladestation sowie für die Überprüfung deren Verschmutzungs- und Leistungsgrad.

I. Übertragungswalze - Die Übertragungswalzenprüfung überprüft die Übertragungsladestation und die Walzenpunkte.

J. Nach-Entwicklungslöschung -Das Nachentwicklungslöschungsprogramm überprüft die Löschungsspannung auf dem fotoleitfähigen Band.

K. Interne Trägerpartikelentfernungsvorrichtung - die interne Trägerpartikelentfernungsvorrichtung liefert bei der Prüfung keine dazugehörige Spannung, da bei dem Untersuchen von falschen Entladungen nicht solche Spannungen auftreten.

L. Externe Trägerpartikelentfernungsvorrichtung - die externe Trägerpartikelentfernungsvorrichtung liefert ebenfalls keine dazugehörige Spannung, da bei dem Untersuchen von falschen Entladungen nicht solche Spannungen auftreten

The LCU can therefore carry out the following test procedures:

A. Main Drive Check - This check checks main timing, transition point detection and the film track for the marker.

B. Automatic set-up phase I- In the first phase of the automatic set-up test, the densitometer and the photoconductor are checked. Then the degree of contamination is analyzed.

C. Automatic Set-Up Phase II - In the second phase of the automatic set-up test, the charging and calibration of the electrometer and the bias offset are checked.

D. Automatic Set-Up Phase III - In the third phase of the automatic set-up test, the process control and the setpoints of the electrophotographer are checked.

E. Automatic Set-Up Phase IV - In the fourth phase of the automatic set-up test, the degree of exposure and the voltage of the photoconductive element are checked.

F. First charging station - The first charging station checks the degree of contamination of the first charging station and ensures that it matches the predetermined target values.

G. Pre-cleaning charging station - This test checks the film for cleaning after transfer and before cleaning.

H. Aftertreatment Charging Station - The aftertreatment charging station program checks the aftertreatment charging station and checks its level of contamination and performance.

I. Transfer roller - The transfer roller check checks the transfer loading station and roller points.

J. Post-Development Erase - The post-development erase program checks the erase voltage on the photoconductive belt.

K. Internal Carrier Particle Removal Device - The internal carrier particle removal device does not provide any associated voltage during testing because such voltages do not occur when investigating false discharges.

L. External Carrier Particle Removal Device - The external carrier particle removal device also does not provide an associated voltage because such voltages do not occur when investigating false discharges

In one embodiment, all of exams A through J are consecutive carried out. Alternatively, the exams can be isolated from each other in order to Optimize the diagnosis of the apparatus 10.

The subsystem tests G-J are evaluated by the electrometer 50, which on End of the exposure process is arranged. The sequencing of the machine is like this selected these charges for only one photoconductor rotation without the first charging station treated to prevent the photoconductive properties of the photoconductor Damage is inflicted. This process is initiated by the timing of the LCU 24, which the check routines of the operation are determined. In the preferred embodiment, the Tests G through J advance test F to measure current cargo efficiency.

In addition, the subsystems can be located at certain points on the photoconductor path activated and reactivated. Furthermore, the electrometer measurements be synchronized so that the collected data of the particular Subsystem check conform.

Photoconductor turns to normal electrophotographic conditions go the Measurement revolution of the photoconductive element ahead and follow it, so that a Regeneration cycle arises.

The LCU 24 is set to perform extensive self-tests of the subsystems that are involved in the generation of an output image. The The LCU 24 process check program ensures that the subsystems responsible for the Imaging are necessary (such as the first charging station, the bias offset and the exposure) are functional. In addition, you will find the program exams that go with it serve to determine whether the subsystems that do not directly contribute to image generation (such as post-treatment charging station, pre-cleaning charging station, post-development deletion and carrier particle removal bias), in the normal Operating tolerances or conditions are.

The data obtained in each subsystem check are with the normal Operating values and applicable error limits compared to a status passed or Fail to determine for each exam. This way a service technician can quickly determine which subsystems are within acceptable limits move, and determine the relative life of other subsystems.

The LCU 24 places the electrophotographic marking apparatus 10 in a normal one Printing plant in which a user uses the apparatus for his task of generating can use electrophotographically produced copies or prints. Additionally poses the LCU 24 the apparatus 10 in a non-printing operation, which is optionally by the LCU is controlled to enable subsystem analysis.

List of reference numbers

10th

Marker

18th

photoconductive tape

24th

Logic and control unit (LCU)

28

first charging station

28a

Charging wires

28b

Grid electrodes

30th

Power supply

32

interface

34

Printhead

36

Data Source

38

Developer unit

40

programmable control

42

Power supply

43

Loading device

46

Transmission unit

47

Corona charger

48

brush

49

Melting unit

50

sensor

51

Power supply

76

Densitometer

152

temporary data storage

154

central processing unit

155

Process and process test module

156

Timing and cycle control unit

158

saved program control

160

Input signal buffer

162

Input data processor

164

Interrupt signal processor

166

Catch register

168

Output driver

S

arc

Claims (13)

Method for operating an electrophotographic marking apparatus (10), which comprises the following method steps: (a) determining a charge efficiency between a first charging station (28) and a photoconductive element (18), (b) generating a reference voltage on the photoconductive element (18), the reference voltage corresponding to the charge efficiency, (c) operating a first subsystem (28, 28a, 28b, 30) in a non-printing operation to generate a first resultant voltage on the photoconductive element (18), and (d) transporting the photoconductive element (18) to a fixed sensor (50) for measuring the first resulting voltage. Method according to claim 1,
characterized in that in a further method step the electrophotographic marking apparatus (10) is set to print operation. Method according to one of claims 1 to 2,
characterized in that the reference voltage on the photoconductive element (18) is restored and a second subsystem (46, 47, 51) is operated independently of the first subsystem (28, 28a, 28b, 30) to apply a second resulting voltage on the photoconductive element Generate element (18). Method for evaluating an electrophotographic marking apparatus (10), which comprises the following method steps: (a) setting the electrophotographic marking apparatus (10) to normal printing operation, (b) selecting a non-pressure setting of the electrophotographic marking apparatus (10), (c) measuring a voltage on a photoconductive element (18) in response to the non-pressure adjustment, and (d) resetting the electrophotographic marker (10) to normal printing. Method according to claim 4,
characterized in that selecting a non-pressure setting of the electrophotographic marking apparatus (10) comprises generating a predetermined voltage on a photoconductive element (18) in the apparatus (10). Method according to one of claims 4 to 5,
characterized in that the voltage on the photoconductive element (18) is measured in response to a predetermined fixed reference voltage. Method according to one of claims 4 to 6,
characterized in that a subsystem (46, 47, 51) of the apparatus (10) is activated which changes a voltage on the photoconductive element. Method according to one of claims 4 to 7,
characterized in that a reference voltage is generated on the photoconductive element (18) before a voltage is measured on a photoconductive element (18) in response to the non-pressure adjustment. Method for analyzing an electrophotographic marking apparatus (10), which has the following method step:
(a) measuring a resultant voltage on a photoconductive element (18) in response to a reference voltage on the photoconductive element (18), the reference voltage corresponding to a charge efficiency of a first charging station (28). Method according to one of claims 1 to 9,
characterized by
that at least one measured voltage is compared with a predetermined value. Method according to one of claims 9 to 10,
characterized in that comparing the measured voltage to a predetermined value comprises comparing the measured value to a series of acceptable values. Electrophotographic marking apparatus (10) with a first charging station (28), a photoconductive element (18) and a large number of subsystems (24, 28, 30, 34, 38, 40, 42, 43, 46, 47, 48, 49, 50 , 51, 76), which has the following elements: (a) a voltmeter (50) at a predetermined location, and (b) a logic control unit (LCU) (24) which is set to create a reference voltage on the photoconductive element (18), the reference voltage corresponding to a charging efficiency of the first charging station (28), and the LCU (24) is further set to selectively switch a subsystem (28, 30, 46, 47, 51) to create a resultant voltage on the photoconductive element (18) and to transport the photoconductive element (18) so that it the voltage meter (50) indicates the resulting voltage. Electrophotographic marking apparatus (10) according to claim 12,
characterized in that the LCU (24) is selected to indicate a current charging efficiency of the first charging station (28).

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