DE2822220A1 - COPY DEVICE AND ELECTROSTATOGRAPHIC COPYING PROCEDURE - Google Patents

Description

PATENT LAWYERS

^ 622220

XEROX CORPORATION

Xerox Square, Rochester, New York

, USA ^:

A. GRÜNECKER

DlPU »β

H. KlNKELDEY

DR. ING

W. STOCKMAIR

CR-Ma-AaE (CALTEOt

K. SCHUMANN

οκ her ναι: om_-Fws

P. H. JAKOB

DlPL-Ma

G. BEZOLD

OH HERΠΜΓ.- E

8 MUNICH 22

MAXIMILIANSTRASSE 43

May 22, 1978

P 12 501 D / 77191

Copier and electrostatographisohes
Copying process

The invention is directed to an electrostatographic copier and an electrostatographic copying method. She wants to improve a copier so that the uniformity of copies becomes better, with the aid of one automatic system for illuminating the photoreceptor of the copier prior to exposing the image.

In electrophotography, such as conventional xerography,

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TELEPHONE (OSfJ TELEX OB-9S3BO TELEQRAMS MONTH TELECOPER

"in which a photoreceptor is charged evenly and then (partially or completely) by an image exposure pattern from the visible Light is discharged to form a latent electrostatic image on the photoreceptor surface, which is then with With the help of visible electroscopic markings, such as toner, can be developed into a visible copy is that Stability or repeatability of the photoelectric Properties of the photoreceptor are essential for a good copy quality.

Several factors are known to be involved in photoreceptor instability. Variations in the characteristics of the photoreceptor known as ⁿ dark discharge ^H are of particular concern. In short, the dark discharge is the discharge of the photoreceptor surface charge, that is, the decrease in voltage measured on the photoreceptor surface that occurs within a certain period of time after the photoreceptor is initially charged. In an automatic copier, the particularly important dark discharge period is the time it takes for the photoreceptor to travel from the charging station to the development station where the electrostatic latent image is developed. The potential remaining on the photoreceptor surface in the unexposed areas (image areas) at the development station is known as "dark development potential ^11. The surface potential remaining in the areas discharged from the iodine is known as" background potential ¹¹ .

In the case of photoreceptors made of a high arsenic selenium alloy in particular, the dark discharge speed becomes influenced by the previous temporal lighting event of the photoreceptor. If the photoreceptor during remains unexposed for a considerable period of time, both the background potential and the dark development potential will vary from one image exposure or copy to another, i.e. between successive images that appear on the

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the same photoreceptor surface can be produced even if the level of charge of the photoreceptor and the amount of exposure for imagewise discharge and the temperature of the photoreceptor are kept constant. Usually achieved the photoreceptor only after several copy images in faster Sequence have been exposed, a temporary stable state of the dark discharge speed in its image area, which is referred to as his state of fatigue. The fre-speed the dark discharge is caused by the image exposure gen increased, apparently due to the generation of increased charge carriers in the photoreceptor. After the exposure is over, i.e. after the copy pass, the dark discharge speed starts rising again over time and temperature, obviously due to the gradual release trapped charge carrier in the photoreceptor

The difference in photoreceptor potential between copies is known as cycle down. It is particularly pronounced between the first copy of a copy run and all subsequent copies of the same run if a noticeable period of time, for example several minutes, has passed since the last previous copy run. (Sin copy run can consist of several copies of a single original, or of several individual copies of individual originals, which are entered one after the other γοη manually, ie in "chain filtering ¹¹ , or from copies that are introduced one after the other from a semi-automatic or fully automatic feed device or a circulation device Typically, all copies of a pass are automatically made in a copier in rapid and even succession.

It has also been found that these stability problems when the copier has been switched off for a long period of time, typically when shut down overnight, worsen and cause copy quality problems when starting the machine.

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carry, collectively referred to as "morning sickness" · This is due to the fact that over such long periods of time between the exposures of the photoreceptor a greater recovery (decrease) of the daily dark discharge speed takes place

The invention aims to reduce or eliminate the copy quality problems described above by a automatic pretreatment of the photoreceptor with a strong Lighting to which it is sensitive, before making the first copy in a copy run, and especially before making copies after starting the copier for the first time. The invention automatically reduces the "cycle down "problems for those photoreceptors that work for this solution are accessible »

The embodiment of the invention disclosed herein is used in an otherwise commonly used automatic copier, similar to the Xerox Corporation "4000" and "4500" copiers, used and built in. Such copiers are known and are described in various related patents. Therefore a detailed description of their components is neither necessary nor desirable here. A useful example of a special one Control circuit for a copier, in which the control system according to the invention described herein can be included, is described in U.S. Patent 3,936,182, published February 3, 1976.

It is known in copiers, and particularly in the Xerox Corporation 4000 and 4500 copiers, after the first Starting the machine, i.e. activating the main relay, for a few seconds, e.g. eight seconds, a pre-copying run with several cycles (dead pass) before copies are made. Are in this dead pass most of the copier's components are switched on, including the charging station and the pre-erase lamp to make the to produce the desired temperature level, to stop the developer

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load, etc. It is also known in the 4000 and 4500 copiers each time the S t art push button is pressed, a single pre-copy run of the machine is carried out, if also for other reasons, before in each of the start pushbutton initiated copy run the first copy is drawn. During these pre-copy passes, the normal Punctures of the charge and the electroluminescent and copy lamp take place, except that the erase lamp is continuously switched on remains to clear the charge on the photoreceptor during the entire Yorkopier run, and not just between the image areas to prevent toner from developing in the image areas.

Examples of common photoreceptors made of a selenium-arsenic alloy, doped with halogen, and their preparation are described in US Pat. No. 3,312,548 and need not be used here to be explained in more detail. The invention does not relate to the manufacture or assembly of photoreceptors. she is applicable to various photoreceptors currently in use or future, but particularly to those of the U.S. Patent 3,312,548. These photoreceptors are known to be sensitive to fatigue caused by red light.

The use of electroluminescent panels that can be switched on in a controlled manner is ready for use for discharging certain areas of a photoreceptor for other purposes and results. Some such light sources are used in the various stations of known xerographic copiers, such as, for example as described herein. An example of such xerographic applications is in U.S. Patent 3,792,913, published February 19, 1974.

Typically, such lamps are commercially available thin "sandwich ^tt" strips of plastic with printed conductors, one of which is a layer of an electroluminescent substance which is electrically energized to be immediately applied by the

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Electric current to produce visible light. These electroluminescent plate strips are attached, for example, in copiers in elongated fastening slots very close to the photoreceptor surface, as disclosed herein, so that they extend uniformly over the entire photoreceptor surface in the axial direction thereof, i.e. transverse to the running direction of the photoreceptor surface past the relevant electroluminescent plates . The Xamps of this type used in xerography typically emit green light. It has also been proposed to manufacture and use red-phosphorescent electroluminescent panels of the construction described herein for other, non-xerographic purposes, for example for illuminating the instrument panel in aircraft. From. Of interest in photoreceptor exposure is U.S. Patent 3,709,683, published 9/9/1973. This describes a uniform exposure of a uniformly charged selenium photoreceptor plate, which contains thallium (and may also contain a small amount of arsenic), since it develops a permanent conductivity, with a source of visible radiation in the range of about 400 to 550 nm to discharge all of the charge on the photoreceptor surface. The plate is then exposed to infrared radiation in the desired image pattern in the range of about 750 nm to 2.75 / 1 ° to form an electrostatic latent image slightly below the photoreceptor surface in the unexposed image areas which can be repeatedly developed with toner so that several copies can be made from a single exposure of the image. The plate is uniformly exposed to infrared radiation to erase the first image before a second image is formed. In column 3, lines 10-15 it is stated that this photoreceptor is practically insensitive to the visible part of the spectrum.

Mention should also be made of US Pat. No. 3,939,436, published February 17. 1976. In it iat the infrared exposure of a photocurrent amplifier device which has a photoconductive layer,

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which may be a selenium alloy for the purpose of eliminating signs of fatigue.

A preferred inventive idea. lies in an automatic System for a copier in which a high intensity visible red light source is automatically turned on, before making any copies at the first press of the copy start switch after the first Einachalten of the copier to illuminate the entire photoreceptor during two complete passes of the same. In addition, will

the photoreceptor on each subsequent press of the copy start switch after the machine has been switched on, automatically this high-intensity light for a single full Cycle suspended before the first in each copy pass Copy is made. The illumination with red light takes place simultaneously with the charging of the photoreceptor but much before the charging area for the photoreceptor and with a higher illuminance, al3 the photoreceptor is otherwise exposed during copying. This pretreatment of the photoreceptor prior to its normal exposure to the image by visible light Reduced fluctuations in the relevant background charges of the photoreceptor between copies, especially for photo- receptors made from a selenium-arsenic alloy.

Further features, details and advantages of the invention emerge from the following description of an exemplary embodiment on the basis of the attached single pig .. This shows: A sonic view of a xerographic copier in an embodiment of the invention,

The Pig illustrates an embodiment of the invention, built into an otherwise essentially common xerographic copier and system. According to the invention However, the system can also work with many different xerographic and other copier systems in different orientations.

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stanchions and constructions are used.

In the pig. a copier 10 is shown which essentially is similar to a Xerox Corporation 4000 copier except for the new features to be described. This includes a lamp control system 12, which operates a red / green lamp 14 controls to illuminate photoreceptor 16 of the copier in a controlled automatic handling cycle. the Lamp 14 has two parts or sections, namely an otherwise conventional green lamp part 18 for pre-extinguishing and one for this new red lamp part 20 of high intensity for tor exhausting, which will be described. Both ropes of the lamp 14 are from the Switched lamp control system 12, which is only shown schematically and contains an Ijampe control circuit 22. How on will be described below, the lamp control system 12 in the present! 'all by the copy start switch 24 and a main switch 26 is controlled.

The system 12 is preferably in the existing machine shop. integrated gik and control system, shown in an example in US Pat. No. 3,936,182, and is primarily never implemented by software programming of digital programmable switching elements and logic circuits, as described there. For a better understanding, this machine logic is embodied herein by the schematic control system 12. A cam controlled Bank counter 28 for the machine logic (as in a copier 4000 or 4500) is here replaced by a crouch 30 operated with two projections, via a sprocket 32 and a chain 34 from the usual rotary drive of the photorecep- Gate drum 16 is driven so that the switch 28 is operated in synchronism with the rotation of the image areas on the photoreceptor 16 will. The switch 28 is with the lamp control circuit 22 connected

As for the basic puncture of copier 10, so is for this purpose the photoreceptor 16 in the form of a cylindrical drum

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with the usual selenium-arsenic alloy along with its xerographic Machiningatationeii shown. In the direction of drum rotation, which is indicated by the arrow, the Surface of photoreceptor 16 first using a suction brush cleaning system 35 cleaned of any residual toner. Any residual charges on the surface of the photoreceptor left after cleaning are erased using a conventional electroluminescent panel erase lamp 36. Then the surface of the photoreceptor is charged uniformly with the aid of a conventional Laäekorotron 38. ! After that, will the photoreceptor in exposure station 40 from a flieas end unevenly discharged light image from light and dark surfaces according to the image. This is done in the usual way using a lamp to illuminate the original, etc. on the photoreceptor, form a latent electrostatic image in Form of a pattern created from charged and uncharged surfaces.

The uncharged interimage areas 62 and 66 on the photoreceptor can then be discharged using a conventional intermediate image electroluminescent panel 42 to prevent that they are developed with toner. (As mentioned above, a pre-copy zero cycle is automatically performed before copying begins carried out in which the interframe lamp 42 is constantly on to prevent development ·)

The photoreceptor surface then goes next to a development station 44 where the remaining ones during copying charged areas of the photoreceptor in usual Way can be developed by applying toner particles. This can be done, for example, with the aid of a magnetic burate development system with four roles, as shown, happen

The developed toner image on the photoreceptor surface is then during prior to its entry into the transfer station

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a copy cycle in a known manner to a pre-transfer corona generator 46 exposed. In the transfer station this image comes with a copy sheet on which the toner image is placed is to be transferred and which was delivered by a copy transport and alignment system 48, for cover. the Transfer of the toner image from the photoreceptor to the copy sheet happens in the usual way with the help of the transfer corotron 50. Then the copy sheet is transferred with the transfer Toner image is stripped from photoreceptor 16 in a conventional manner by means of a stripping corotron 52 and a squeegee 53 and directed to a paper guide 54 with suction box. The peeled copy sheet is then fed into the Gap of a fuser 56 passed in which the toner image is fused in a conventional manner on the copy sheet.

The photoreceptor 16, the now remaining, untransferred one. Toner carries first passes under the red / green lamp unit 14, which will be described later. In normal In copy mode, the photoreceptor 1.6 is only exposed to the light of the green electroluminescent lamp part 18 for pre-extinguishing, which discharges most of the remaining surface charge on the photoreceptor. Then the photoreceptor discharged further in the usual way by the pre-cleaning corotron 58 before it comes into contact with the cleaning brush 35 is brought, which ends the cycle. Before copying, however, the lamp unit 14 has a completely different function, namely as a red light source to illuminate the photoreceptor to serve the purpose of pre-exhaustion

As can be seen, the red / green lamp unit 14 is in the example shown regarding the location of the other usual components of the copier in the normal place for a conventional, exclusively green pre-extinguishing lamp. This particular position is favorable because of the compactness, but not essential to the invention. However, it is beneficial if the lamp

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unit 14 well above the charging station 38 in Direction of travel of the photoreceptor is arranged as this Mer the case is. On the photoreceptor, which is designed as a cylindrical drum, this point is about 90 degrees ladekorotron 38, When choosing this position, the aim is to that no throughput is lost, i.e. no additional {drum turn or half turn before copying is necessary id.rd, to achieve a full goal fatigue cycle. This would be the Pail if the lamp unit 14 were to be attached in place of the lampef42, for example.

As for the construction of the red / green lamp unit 14 in As far as detail is concerned, in the example shown this is a single lamp with two parts or sections, which is preferable is. It should be noted, however, that two separate lamps can be used instead. The two parts of the larape, namely the green section 18 for pre-extinguishing and the red section 20 of this lamp, have in the direction of the Photoreceptor has a uniform width} but the widths of the two parts are different from each other. And stretch the parts unimpeded across the entire photoreceptor · The entire lamp 14 has a uniform small distance from the photoreceptor. This distance in the example is approximately 4 mm above the surface of the photoreceptor, which is a is the usual distance of a strip or plate lamp. The illuminance or radiation is uniform over the length of the two lamp parts. When the lamp parts are turned on are, they illuminate the entire surface of the photoreceptor drum 16 evenly «They are not intended or suitable for it, to expose the photoreceptor to an image. The three wires that connect the lamp 14 to the lamp control and power supply circuit 22 connect, make it possible that the circuit 22, the two separate lamp parts on controlled Selectively operated manner, as will be described in more detail.

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The entire lamp 14 can be constructed from a commercially available, commercially available green phosphor-based electroluminescent panel in the form of a plastic strip, similar to the panels used in the Xerox Corporation 4000 and 4500 copiers, except for the modifications described below. The lamp 14 is modified in such a way that it is divided into two unequal pieces of rope with separate electrical connections. The larger section of the lamp, since it is approximately 2.5 cm wide, has a continuous covering (transparent piIm or layer) 21 made of a red fluorescent vinyl plastic, for example a commercially available polyvinyl chloride layer doped with a commercially available red phosphorescent material. This red plastic layer 21 is not just a pilter, and in fact it may even absorb 90% of the green light from the lamp section below. Their main light emission is the red phosphorescence, which is generated by the absorbed light, in a fluorescence conversion. This red layer 21, its surface, and the separate electrical power supply to its underlying lamp part provide the desired emission strength of the red lamp part 20. The approximately 1 cm wide, film-free separate part of the lamp 14 provides the green lamp section 18 used for pre-extinguishing.

The red lamp part 20 for goal fatigue emits light in the spectral range in which the photoreceptor is particularly sensitive to lighting pre-fatigue, i.e., a rapid change in the dark discharge rate due to lighting with this special light source, without the need for a particularly high-energy light source. In the present In this case, the spectrum of the pre-exhaustion lamp is a visible red light that has its maximum at 620 nm. This lies within the visible Eot range of 600 - 700 nm, and not in the infrared. With a phosphorescent lamp, as in this one If necessary, the light emissions can be as desired visible spectral range are concentrated and compared

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to a thermal! luminescent lamp more evenly over the Photoreceptor are distributed.

Both parts or sections of the lamp 14 can be of a conventional one Energy source can be fed with frequency converter, but with separately adjustable currents · The two. Sections 18 and 20 are given separately in this pail adjustable supply voltages from a power source with 790 Hz 170V and square wave form. The 790 Hz frequency is a lot higher than the typical operating frequency for these electroluminescent panels in a copier of 60 or 400 Hz. It is used here to provide a higher lighting intensity, since the brightness of such lamps is a puncture of both frequency and voltage, but especially frequency. the Increasing the frequency to over 700 Hz generates a multiple of the light output compared to an energy source with 60 Hz line frequency.

In the present case, the power supply to the red lamp part 20 is set to a high luminosity, measured on the lamp surface, of between 4 and 20 microwatts per square centimeter set for the specific lamp and photoreceptor. This luminosity and / or the emitting lamp surface and / or the color used may vary depending on the particular Photoreceptor vary. This example of the emitted light intensity and the lamp area is the same as that mentioned above Spectral range sufficient to achieve the desired pre-exhaustion discharge of the photoreceptor in this example. The lamp 14 described above is particularly useful, however, other suitable light sources of high luminosity can also be used. The following is the function of the lamp control system 12 described in more detail. The control system 12 operates in two different modes of operation, two different ones Functions and operations of the red lamp portion of lamp 14 to provide. In the first operating mode this is the case Turn on power to the copier, i.e. to be there-

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turn on the machine, along with the initiation of the first Copy pass (here by the copy start switch 24) the way over the Laapensteuerungs- and Hetz circuit 22 that the Eotlampa 20 is switched on and two full machine cycles long, i.e. The drum remains on for two full revolutions along with the other xerographic Components that work on the drum. All of this happens automatically before the first copy is made, i.e. before the first copy sheet is advanced through the copy transport and racking system 48 into the transfer station will. In other words, this mode of operation takes place every time the copier 10 is used for the first time is turned on in the morning, a pre-fatigue treatment of the Photoreceptor during two cycles by the high-intensity red light from the lamp part 20 instead. This happens automatically immediately prior to making the first copy (and all other copies made in the same first copy pass, there the cycle is started by the same actuation of the copy start switch 24). Copying will then start automatically immediately after the end of the two pre-fatigue cycles without stopping the drum. The lamp control circuit 22 automatically switches off the Eotampe 20 and to extinguish it serving 6-green lamp 18 for their normal and usual operation as soon as copying starts.

The second and additional automatic mode of operation of the lamp control system 12 runs after the first operating mode has ended, i.e. when the copier is in a waiting state and is energized. Each subsequent actuation of the copy start switch 24 automatically switches the Rotlaapa 20 for a single pre-exhaustion cycle, i.e. in the present Pail one revolution of the drum to pre-light the photoreceptor once before copying. Then it will be As in the other operating mode, the red lamp part 20 is automatically switched off and the green lamp part 18 is switched on, in order to immediately afterwards all copies in the same run,

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i.e. by the same operation of the copy start button 24 to manufacture.

In both operating modes takes place continuously during the geeaaten Pre-copy pre-fatigue cycle or cycles a regular charge of the photoreceptor by the charge corotron 38 a little behind the red laap part 20 instead.

These two different types of yore fatigue with an automatic Pre-fatigue lighting of photoreceptor 16 during two periods of time of different length (a longer lighting at the first start and a shorter lighting at the start each subsequent copy pass) provide two target different pre-fatigue levels of the drum for two different ones Photoreceptor states caused by two different machine states.

For both operating modes, the result is a reduced one "Difference between the background charging of the photo- receptors for the first copy and those for the "long copy and the subsequent copies compared to the difference that would arise without such pre-exhaustion" So can, for example, without the system according to the invention, the image background voltage άβ3 latent electrostatic image dea photoreceptor, measured just before development, between the first copy and subsequent copies of the same run drop by 100 V from the same initial charge. At the In the present system, it was observed that this drop was correctable to only about 30 volts. This represents a significant improvement in the persistence of the background voltage between the Copies are. Ss allows an easier adjustment of operating parameters of the machine, for example the developer preload and charging and thereby improved stability and quality of the copy over a wide range of operating conditions and times of the machine. No changes in the copier system (illumination of the original) are required.

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This means that any desired light source can be used will·

The high intensity pre-exhaustion lamp 20 achieves pre-exhaustion of the photoreceptor by generating additional charge carriers in the photoreceptor material, so that the surface charge of the photoreceptor dissipates faster with the first few copies than it would otherwise. the dark discharge speed is increased by the pre-exhaustion to a speed that is otherwise usual.

se would only achieve after some Copies are made one after the other. In other words, as As a result of pre-exhaustion, the surface potential of the photoreceptor falls much faster than it would otherwise with the first few copies. Consequently, both the intensity as well as the spectrum used will vary provided their interrelated effect on the photoreceptor achieves the desired change in dark discharge rate within the available time »The pre-exhaustion luminosity on the photoreceptor within the real spectrum, in which the photoreceptor effectively releases internal charge carriers to rapidly change the dark discharge rate, is greater than the illuminance within the spectrum of the copy lamp (illumination of the original) or any other light source that acts on the photoreceptor during copying.

However, the pre-fatigue cycle must be practically immediate (a.B. less than a minute) before making the first copy. Otherwise the dark discharge speed increases after pre-fatigue quickly returns to its previous value without fatigue before the copy run begins. In a copier 4000 or 4500 can be used in the pall of the first pass after switching on, i.e. in the first mode, the two Pre-fatigue cycles at the beginning of the allotted eight seconds take place in the continuous build cycle period before copying

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and yet be effective. However, it is preferable especially for all other copies that the pre-fatigue cycle occurs immediately before the first copy cycle is performed with no delay therebetween.

Seibat in the first operating mode has proven to be useful no more than two complete pre-fatigue cycles to provide with red light illumination of the photoreceptor before the first copy, even after a long rest. Significant pre-exhaustion, for example from longer or more intensive lighting of the photoreceptor, can actually cause an inverted or upward dispensing condition of the photoreceptor, i.e. the background voltage can be for the second and subsequent copies relative to the first copy by one increase in value. In this example, the pre-exhaustion lamp is switched off completely before the first one Copy image is made on the photoreceptor. Increasing the number of pre-fatigue cycles is also beneficial from the standpoint of Copy throughput is undesirable because it increases the copy-free time and the loss of time between passes gets bigger. The two different types of pre-erasing those described above are particularly favorable because of the fact that the problem of falling is all the more serious is the longer the photoreceptor 16 has been idle, i. e. not exposed and not used for copying »It is therefore very beneficial to automatically add an additional pre-fatigue cycle only when the copier is started for the first time, how this is done according to the invention

It should be noted that in the synchronous type copier 10 shown herein, the photoreceptor 16 is placed on each revolution of the photoreceptor drum is exposed in two separate, in their position unchangeable image areas 60 and 64, which by two always unexposed dead bands 62 and 66 are separated from each other two copies can be made. Many copiers are not

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synchronously, with the number of image areas and copies per drum revolution depending on the drum circumference, the sheet length the image areas and the distance between them on the perimeter can change. Thus, when the term "pre-fatigue cycle" is used herein is used, it refers to a single full exposure of all that is used for subsequent copying Image areas. Depending on the initial position of the drum, the location the image areas and the arrangement of the pre-exhaustion lamp A pre-fatigue cycle can sometimes be completed in less than a full drum turn, or it can be completed in others Cases require a little more than a full drum revolution. In the system described here, one cycle in one Drum revolution is carried out and the plate 60 is exposed before it ends.

In many common copier machines, the machine is first switched on with a conventional main switch. This is usually connected to a strobe relay inside, which supplies the machine components with power. Ordinary is a delay period for "heating up" is necessary before the Machine runs, especially if the copier contains elements such as a fuser roll that require a longer heating time require.

Usually this is used to actually initiate the copying process In most copiers, a separate copier start switch is operated by the user of the machine after the The machine has been switched on beforehand and has had time to heat up. This is typically a switch that the operator manually after placing an original to be copied in the copier. However, it is mentions that the copy start switch for the first or all copies can be a switch of that instead leading edge of an original is operated, which is in a Document feeder of the copier is introduced. This copy start switch sets the machine for the copying process

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drove, i.e. sets the photoreceptor in motion, as well as that Exposure system, copy sheet transport, etc. · The operation the start copy button can cause the machine to make only one copy. Mostly it does however the one-time actuation of the copy start switch that the machine continues copying through several copy cycles »where the number is determined by the presetting of copy selection switches by the operator. I.e. the machine is running continue until the set total number of copies has been made for this copy run. Then the machine switches to typical case to a waiting state in which the machine is still energized, but the photoreceptor and other components have stopped and ready for the next actuation wait for the start copy switch, which can be seconds or hours later. Typically, the machine remains in this waiting state during office hours while the machine is being used. At the end of office hours, the power supply is switched on switched off to the machine, for example by means of a separate off switch, which is separated from the copy start switch is.

For example, in the Xerox Corporation 4000 and 4500 copiers, the power supply is switched off with this main switch 26, but not switched on with this switch 26. Rather, in these special machines, the power supply is switched on by pressing the start copier holder 24 for the first time. After a pre-set heating-up time and a pre-set zero continuous running time, as already the machine is ready for copying, which is then done by depressing the same copy start switch a second time 24 is initiated. The power supply remains switched on after starting sohaltera 24 with the first actuation of the copy connected to the machine until the main switch 26 is pressed to cut off the power to the copier

In the specific system the copier 4000 and 4500 switches

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thus the main senior member 26 only surrenders the electricity; however, the system of the invention is not limited to this arrangement. Rather, the puncture and the state of the machine are important in the system according to the invention, which is the difference between the state of the machine when the power supply is switched off versus the waiting state between the passes, regardless of the switch used. This is because after switching off the machine Photoreaeptor typically is for a much longer period of time, such as on _(night, unlit So the Photoreaeptor has a ι longer period for recovery of Dunkelentladungsgesohwin- |. Had speed, because it is time-dependent. As a result, treatment with lighting for pre-fatigue is more necessary to bring the dark discharge rate back to the value that normally occurs during a copy run. It is therefore advisable to have two pre-fatigue cycles immediately before making the first copies after switching on the power , on the other hand, only one preheat cycle immediately before the first copy in all subsequent runs after the machine has already been switched on. This system has the additional advantage that no significant additional logic or circuitry is required and the existing electrical signals of the machine are shared can.

As an alternative embodiment of the system described above, an alternative system can be used in which a conventional electrical timer measures the time that has elapsed since the immediately preceding copy run, among other things automatically select the pre-exhaustion mode. When the elapsed The time that the timer that can be started by the copy start switch has measured a predetermined one Exceeds a period of time, for example more than an hour, then the machine is automatically operated for two pre-fatigue cycles, as already described, immediately before the first copy in the next copy run. This can be done automatically

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by pressing the copy start switch for the first time after the elapsed time. This system can be sent to the Step in place of the initiation of the first operating mode described above or in addition to it, with the power supply to the machine is switched off between the copy runs · If, on the other hand, the next activation of the copy start button there is a shorter time after the previous copy run than corresponds to the set time period, 2.B. after less than an hour, then the second operating mode described above occurs with only one pre-fatigue cycle before the first copy of the copy run. This system can do that have the same appearance as previously described, as this timer is simply integrated into the lamp control and power supply. circuit 22 can be incorporated. Every time the copier Start switch 24 is operated, this internal timer is automatically reset to Hull so that it starts running again and continues to run until the start copy switch is next Is pressed once, whereupon the timer is reset to zero and makes the selection of the operating mode by comparing it with the set time period

As a second alternative, instead of being switched off by the first exposure of an image in the image area, the pre-exhaustion lamp can continue to operate, but its intensity is automatically reduced for the first few copies in one copy run. For example, the Id.chtau8beu.te the Vorermüdungslampe, after the first copy does 50 i »reduced after the second copy by another 50 i" and then switched off after the third copy, "Torermüdung would start but preferably also at its highest Iatensität for an exposure cycle before the first copy (first exposure) of the image area of the photoreceptor. It would also be reduced to a low level or completely terminated during the first few copies of a copy run

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in the preferred embodiment, the control of the preheat lamp automatically their emitted luminous intensity when starting a copy run ♦

To sum it up briefly: The above describes an improved device and system »to latent persistence of electrostatic images on the photoreceptor of a copier »in order to improve the quality of the Increase copy and improve machine maintenance. Device and. System according to the invention are characterized by simplicity, low cost and fully automatic puncture and require no operator effort.

Compared to the exemplary embodiments described herein, which are considered expedient, various modifications are possible within the scope of the invention, which is given by the claims.

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Claims (16)

"ATEivTANWÄLTE A. GRÜNECKER URL-ING H. KINKELDEY W. STOCKMAIR DR-INQ '/ WE (CAUEOI K. SCHUMANN OR HER NAT. · DIPL-PHYS P. H. JAKOB DlPL-INa G. BEZOLD ORRERNAr DlPL-CHEM. 8 MUNICH 22 MAXtMlLlANSTRASSE 43 Patent claims ) Electrostatographic copier using a photoreceptor repeatedly charged uniformly and in an image area by means of an exposure device with visible Light is imagewise exposed with a predetermined maximum illuminance in order to during the copy passes create a developable electrostatic latent image on the photoreceptor having a dark discharge rate normally between the first copy and subsequent copies of a copy run can vary considerably due to photoreceptor fatigue, characterized by an automatic pre-fatigue system for the photoreceptor, accelerated light fatigue of the photoreceptor prior to making the first copy in one copy pass provides and the one pre-fatigue lighting device (20) for uniformly illuminating the photoreceptor on its image area with pre-exhaustion lighting, the intensity of which is considerable is greater than the exposure intensity of the exposure device when exposing the image within a spectrum of light in which the photoreceptor is effective 809848/0930 TELEPHONE (OSO) Q2 2Sea TELEX OB-SB38O TELEGRAMS MONAPAT ΤΚίΕΚΟΡΙΕΒΒΒ nÄlkJAl ~ 2B22220 internal charge carriers are released, so that the dark discharge rate changes rapidly, and also a control (22) for the pre-exhaustion lighting containing the pre-fatigue lighting device (20) only for a certain limited yore lighting of the image area actuated, controlled by a previously selected state of the copier, wherein the controller (22) is for the pre-exhaustion lighting automatically initiates the pre-avoidance illumination of the photoreceptor before the photoreceptor uses to copy and automatically the photoreceptor's fatigue lighting reduced by the previous lighting device (20) when initiating a copy run. 2. copier according to claim 1, characterized in that the exhaust lighting device (20) emits mainly visible hot light onto the photoreceptor. 3 · copier according to claim 1, characterized in that the pre-roughening lighting device (20) is a red-phosphorescent light source that shines light on the photoreceptor emits in a spectrum that has its maximum at 620 nm. 4 · copier according to claim 1, characterized in that the fatigue lighting device (20) is a sheet metal luminescent panel which extends closely across the photoreceptor and as red phosphorescent Light source bat a hot light emitting surface 5. copier according to claim 1, characterized in that the control for the pre-exhaustion lighting is designed in such a way is that they have a longer pre-exhaustion lighting of the Photoreceptor provides before the first copy after the first power-up of the copier than before the subsequent ones Copies made after the copier is loaded 809848/0930 is already switched on 6. copier according to claim 1, characterized in that the copying process by actuating a copy start switch (24) is initiated and that the control of the pre-fatigue lighting is automatically initiated from the copy start switch he is operated. 7. Copier according to Claim 1, characterized in that the control for the pre-exhaustion lighting has two operating modes which has two different lengths of pre-exhaustion illumination of the photoreceptor by the pre-exhaustion illumination device (20) provide, and that the pre-selected state of the copier, which automatically selects between the two operating modes, the first application of Power to the copier is » 8. copier according to claim 1, characterized in that the control for the pre-exhaustion lighting two operating modes which has two pre-exhaustion illuminations of the photoreceptor of different lengths by the pre-exhaustion illuminating device (20) provide, and that the pre-selected state of the copier, which is automatically between selects the two modes of operation, actuating the controller in response to a predetermined maximum elapsed time between the initiation of successive copying runs is 9 · Copier according to claim 8, characterized in that the copying runs are activated by a copy start switch (24) in (rank and that the controller (22) has a resettable timer for measuring the between actuations the copy start stop holder has passed the time 10. Electrostatographic copier, in which during the 809848/0930 Copying a photoreceptor with a selenium-arsenic alloy is charged evenly and given by some exposure devices working with visible light maximum illuminance is exposed to on the photoreceptor for each copy in rapid uniform succession during pre-beating copy duration runs a developable, forming latent electrostatic image, the photoreceptor has a dark discharge rate normally between the first copy and subsequent ones Copies of a copy run due to the idling of the Photoreceptor increases significantly, characterized duroh an automatic fatigue system for the photoreceptor, the one accelerated photoreceptor fatigue immediately gate the making of the first copy in each Provides for a copy run, and the one goal fatigue lighting device (20) for evenly illuminating the photoreceptor with an intense light in the visible red spectral range with an illuminance in this spectral range that is essential is greater than the lighting intensity of any other lighting device, about the dark discharge speed greatly reduce and furthermore a controller (22) for the exterior fatigue lighting which the pre-roughening lighting device (20) only for a predetermined limited lighting of the Turns on the imaging surface, the exposure time of which is controlled by a preselected state of the copier, depending on the previous period of non-use of the photoreceptor and starting with the activation of the copier for a copy pass, the controller (22) the lighting by the pre-erasing lighting device (20) automatically practically terminated when the predetermined pre-fatigue exposure time has elapsed and before the copy run in the copier has been completed 809848/0930 11. copier according to claim. 10, characterized in that the pre-fatigue lighting device (20) is a red phosphorescent light source, which on the photoreceptor light in one. Spectral range with a maximum emitted at 620 nm. 12. copier according to claim 10, characterized in that daduroh the control (22) for the pre-fatigue lighting is constructed in such a way that it has at least two lights of the Photoreceptor immediately before the first copy run after switching on the copier for the first time, on the other hand only initiates a single illumination of the photoreceptor, immediately before each subsequent copy run, after the copier has already started, this illumination being terminated before the copy run concerned begins. 13. copier according to claim 10, characterized in that the copying by the operation of a copy start switch (24) is started and that the control (22) for the pre-exhaustion lighting automatically by this copy start switch is operated. 14 · Blektrostatographisohes copying process in which a photoreceptor of a copier repeatedly charged uniformly and into an imaging area by exposure to visible light is imagewise exposed with a predetermined maximum illuminance to on the photoreceptor to form a developable electrostatic latent image during the copying runs, as well as being evenly illuminated by other lighting sources during the copying process with the photoreceptor having a dark discharge rate which normally varies significantly between the first copy and subsequent copies of a copy run due to light fatigue of the photoreceptor, 809848/0930 characterized in that the photoreceptor across the imaging area prior to copying in an intense Pre-fatigue lighting in a spectral range in which the photoreceptor effectively releases internal charge carriers, in order to rapidly increase the dark discharge speed, is automatically and evenly illuminated, with the illuminance in this spectral range is much greater than the intensity of any other source of illumination, since the photoreceptor is exposed during copying, that the pre-fatigue lighting of the photoreceptor only for a predetermined limited exposure time is made by a preselected state of the copier is controlled, and that the pre-exhaustion lighting when starting the copying process automatically terminated or at least significantly reduced. 15 · copying process according to claim 14, characterized in that the pre-exhaustion illumination is mainly visible red light is. 16. copying method according to claim 15, characterized in that the pre-fatigue lighting in a spectral range with the maximum at 620 mn 17 · Copying method according to claim 14, characterized in that the pre-exhaustion lighting before the first copy run after the first start-up of the copier is automatically made longer than for all subsequent ones Copy runs after the copier has started up. 18 · Copying method according to claim 14, characterized in that copying is effected by actuating a copy start switch is initiated and that the pre-fatigue lighting 809848/0930 automatically switched on before this start copy switch, 19 · copying method according to claim 14 »characterized in that the pre-exhaustion lighting is on the ehotoreceptor in a considerable distance from the uniform charge is brought into action. 809848/0930