CA1092639A - Photoconductor charging technique - Google Patents
Photoconductor charging techniqueInfo
- Publication number
- CA1092639A CA1092639A CA250,130A CA250130A CA1092639A CA 1092639 A CA1092639 A CA 1092639A CA 250130 A CA250130 A CA 250130A CA 1092639 A CA1092639 A CA 1092639A
- Authority
- CA
- Canada
- Prior art keywords
- photoconductor
- charge
- station
- voltage source
- generator
- 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
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
- G03G15/28—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning
- G03G15/30—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning in which projection is formed on a drum
- G03G15/307—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning in which projection is formed on a drum with more than one photoconductor revolution for each copying cycle
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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
- G03G15/02—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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Control Or Security For Electrophotography (AREA)
- Discharging, Photosensitive Material Shape In Electrophotography (AREA)
- Combination Of More Than One Step In Electrophotography (AREA)
Abstract
PHOTOCONDUCTOR CHARGING TECHNIQUE
Abstract In an electrophotographic copying device having charging, imaging, developing, transferring, precleaning and cleaning facilities, the arrangement being in the conventional sense, but incorporates a combined charging and precleaning unit that is operable to perform either the charging function or the precleaning function at the proper time during the copying/cleaning cycle. A combined precharging/transferring unit is also incorporated to facilitate precharging or transferring at a predetermined time during the copying process.
Abstract In an electrophotographic copying device having charging, imaging, developing, transferring, precleaning and cleaning facilities, the arrangement being in the conventional sense, but incorporates a combined charging and precleaning unit that is operable to perform either the charging function or the precleaning function at the proper time during the copying/cleaning cycle. A combined precharging/transferring unit is also incorporated to facilitate precharging or transferring at a predetermined time during the copying process.
Description
16 Background o~ t]~e Invention 17 1. Field of the In~ention 18 The invention xelates to an electrophoto-19 graphic copylng device and more specifically, to an improvement over the charging and 21 cleaning of the support surface on which 22 the latent image of an original is developed.
23 2. Prior Art 24 The following U. S. Patents are representative of the prior a'~t: V. S. Patents -26 3,647,293; 3,637,306; and 3,736,055.
27 Numerous prior art teachings in the field of electrophotographic or xerographic .....
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1 copying teaches various methods and devices
23 2. Prior Art 24 The following U. S. Patents are representative of the prior a'~t: V. S. Patents -26 3,647,293; 3,637,306; and 3,736,055.
27 Numerous prior art teachings in the field of electrophotographic or xerographic .....
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1 copying teaches various methods and devices
2 for prep~ring the surface of a photoconductor
3 so as to obtain a latent image from an original
4 copy. Prints are then transferred from the latent image on the surface of the photo-6 conductor, to a transferring media.
7 To enable the development of the 8 latent image on the photoconductor and the g transferring of said latent image to a trans-ferring media, several stations are arranged 11 in proximity to and to cooperate with the 12 photoconductor to perform certain functions.
13 At the charging station, the photoconductor - 14 is charged negatively. rrhe photoconductor then moves to the exposing or imaging station 16 where a latent image-is copied from an original.
17 Next, the electrostatic :Latent image is 18 developed at a developer s~ation to form 19 a t~ner image on the photoconductor. The ; 20 toner image is then transferred from the photoconductor to another media at ~he transferring 22 station. To complete the cycle~ the photoconductor - 23 is erased, precleaned, and cleaned and is 24 then ready for another cycle.
Although the prior art electrophotographic 26 devices function adequately for the intended 27 purpose, several problems plague the systems.
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1 Probably one of the pressing problems is the Fact that the charging, transferring and precleaning functions are all performed by separate corona units at separate stations. With this type of prior art design, the cost of the electrophotographic device is relatively high, due to the individual cost of each corona unit. Since the general trend is to minimize the cost of electrophotographic devices without sacrificing efficiency, any reduction in the number of component counts in the prior art devices will be welcome.
Another problem relating to the separate processing station is the fact that each of the separate corona units require a separate power supply. The aggregate cost of these power supplies further augments the overall cost of the unit. As such, any reduction in the number of power supplies will result in cost reduction oF the unit.
It is common knowledge, that conventional electrophotographic devices may be either a single cycle process or a two-cycle process. In the typi-cal two-cycle process, the photoconductor is charged, imaged and developed during the first cyclei while the image is transferred and the photo-conductor is cleaned in the .
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1 second cycle. For satisfactory op~rations, 2 some of the stations which render necessary 3 functions during the copying process are 4 active during the first cycle, while others are inactive and vice versa. On account 6 of the rapid speed at which the photoconductor 7 would access each of the stations, it is 8 therefore necessary for high speed switching 9 to occur at these stations. The conventional 60 cycle power supply which is used for 11 supplying power to these stations cannot 12 withstand high speed switching, With these 13 drawbacks, it is clear that a more efficie~t 14 device is needed.
Several attempts have been made 16 to improve the prior art electrophotographi¢
17 devices by solving some of the above-identified `~
18 problems. For example, attempts have been 19 made to combine the charge and the transfer corona station. At first blush, this combination 21 seems to be workable and logical; since i 22 the function of both stations is to supply 23 negative charges. However, the combination 24 instead of solving the above described problems creates additional problems.
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26 One of the additional problems 27 stem from the fact that the combined charge 28 transfer station is designed with a grid . . ..
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1 structure to enhance the charge operation. However, transferring media which is fed into the machine at the charge/transfer station for trans-ferring the latent image from the photoconductor jams into the grid wires. This jam results in machine breakdown.
For proper operation, a negative charge has to be deposited onto the transferring media so that the positively charged toner particles will be attracted. With the presence of the grid assembly in the com-bined charge/transfer station, the negative charge cannot be uniformly distributed onto the transfer media. With an uneven distribution of charges, the quality of the final copy is less than satisfactory.
Objects of the Invention It is, therefore, the object of the invention to design a more efficient, low cost electrophotographic device than has heretoFor been possible.
It is another object of the present invention to build an electro-photographic device with fewer corona units than has heretofor been possible.
It is a Further object of this invention to combine the preclean and charge corona units into a single unit.
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1 It is still a further object of the present invention to use the transfer corona station to render the precharging and the transferring functions.
~ummary of the Invention The present invention overcomes the aforementioned drawbacks in the prior art by means of a unique structural combination of processing stations within the copying process. More specifically, the invention discloses a unique two-cycle process for an electrophotographic copying device. In one feature of the invention during the first cycle, the photoconductor is overcharged to a first polarity by the combined pre- -charge transfer corona unit (Corotron), the overcharge is then reduced by an opposite polarity combined chargejpreclean corona unit (Scorotron).
Imaging and developing also occurs during this first cycle.
During the second cycle, the toned image is transferred to the transferring media using the same precharge transfer corona unit (Corotron).
Following transfer, the drum is charged by the charge/preclean corona unit to a second potential for cleaning. In order to place the second charge level or potential on the photoconductor drum, ,. .
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1 the grid of the charge/preclean corona unit is switched to a different voltage (either the same or opposite polarity or ground as required to obtain best cleaning). The drum is then (optionally) erased by the erase lamp, and cleaned by the developer.
In another feature of the invention, the photoconductor is over-charged by a first or auxilliary corona unit at a precharged station.
The charge is then reduced to a uniform value by a second corona unit of opposite polarity at a final charge station. The photoconductor is then ready for imaging and developing.
In another feature of the invention, the photoconductor is charged to a very uniform negative value by means of a positive final charge corona unit which yields more uniform emission than a negative corona -unit.
Another feature of the invention is the use of a gridded corona unit (Scorotron~. to perform the preclean function. The increased control of the preclean photoconductor voltage because of the grid structure may eliminate the need for the preclean erase lamp function.
The improved cleaning action has reduced the hole and electron carrier intensities in the photoconductor which also reduces the fatigue effects of the photoconductor.
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The foregoing and other objects, features and advantages of the invention will be apparent From the following more particular descrip-tion of the preferred embodiment of the invention, as illustrated in the accompanying drawings.
Brief Description of the Drawings FIGURES 1 and 3 are a schematic diagram of a two-cycle process electrophotographic machine showing a plurality of processing stations which incorporates the present invention.
FIGURE 2 is a schematic diagram showing the control circuit which changes the voltage of the control grid in the combined charge/preclean station.
Detailed Description ` The term corotron as used in this application means a type of corona unit having either limited or no grid structure. In effect the corotron may be cons;dered analogous to a current source.
The term scorotron as used in this application means a type of corona unit having a grid structure. The scorotron may be considered as a voltage source.
For explanation purposes, the photoconductor in the preferred embodiment B09-74-050 _ 8 _ ..
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1 of the present invention will be described 2 as a rota~ing drum. Elowever, this should 3 not be cons-trued as a limitation on the 4 scope of the invention; since it is well known in the art to design a pho-toconductor having a different shape, size and mechanical 7 configuration. For example, the photo-8 conductor may be a continuous belt or a plate 9 rather than a rotating drum structure.
Although the preferred embodiment 11 of the invention is described in association 12 with a two-cycle copying process, this should 13 be interpreted as only illustrative rather 14 than restrictive, since it would be obvious for one skilled in the art to modify the 16 inventive feature as disclosed hereinafter 17 to malse said concept operable in a one-cycle 18 copying process.
19 Referring now to FIGURE lf a pictorial view of an electrophotographic copying system 21 10 which embodies the present invention 22 is shown. A cylindrical drum 12 herein-23 after called a photoconductor is mounted 24 for rotation on shaft 14 and having on its ouker periphery a photoconductive insulating 26 layer which contains an organic ox inorganic 27 photoconductor material. The drum 12 is i Z8 ro~ated to bring the photoconductive layer ,, '. ~.
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1 -to various stations associa-ted with the 2 electrophot'ographic process; each of said 3 stations being positioned in proximity to 4 the rotating drum.
A negative corotron 18 is positioned 6 within the orbit of cylindrical drum 12 7 to define the so-called precharge/transfer 8 station 32. Negative corotron 18 of the 9 precharge/transfer station serves two functions, namely: to deposit an excess of negative 11 ions on the surface of the photoconductor 12 (for example, -1300 volts) and to deposit 13 negative ions-on a transferring media, for 14 example, paper so as to transEer a latent - 15 toner image from the surEace ofl the photoconductor.
16 As will be explained subsequently, the negative 17 charge which is deposited on the photoconductor ' 18 by nega~ive corotron 18 is rough; i.e., 19 the charge is unevenly distxibuted on the ' surface of the photoconductor.
21 After precharge/transfer station 22 32, the next sta-tion in'order is the combined 23 final charge/preclean station 20. Finally, 24 charge/preclean station 20 is the facility which supplies the final charge to the surface 26 of the photoconductor'and renders the preclean 27 function. This final charge is referred 28 to as smooth due to the fact that the charge ` ' .
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1 is evenly distributed over the surface of the photoconductor because of the cut-off characteristic produced by the control grid. As will be explained subsequently5 the polarity of the emission wires in the final charge/preclean corona is opposite to the voltage applied to the precharge/transfer corona unit. In the preferred embodiment, a posi-tive emission voltage is used so that positive ions are generated.
Final charge/preclean station 20 comprises a positive scorotron 22.
Scorotron 22 supplies positive ions at station 20. The positive ions reduce the rough charge on the photoconductor surface to a smooth charge.
Grid structure 24 is positioned between scorotron 22 and the photocon-ductor 12. The function of grid structure 24 is to control the flow of positive ions which are deposited on photoconductor 12 and hence, the resulting photoconductor voltage.
As will be expl~ined subsequently, and as shown in FIGURE 2, a switching circuit is connected to grid 24 to control the voltage on the grid. For example, in one instance the voltage on the gris is very negative (approximately -700 volts), while in another instance the grid is slightly positive ';' ' :
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l~D~63~ 1 1 (approximately +50 volts). Still in another 2 ins-tance, the voltage may be slightly negative 3 (approximately -50 volts) or ground.
4 The other station in order is the so-called interimage 26. The interimage 6 stati~n comprises high intensity lamp 28 7 and the function is to erase images on the 8 sides of the photoconductor depending on 9 the size of the document to be copied. During the second cycle, this lamp can be option-11 ally turned on to erase the photoconductor 12 to aid in the cleaning process.
13 The next station in order is the 14 image station 30. Imàge station 30 COmpriSQS
a conventional optical system Ihich functions 16 to transfer a latent image of a document 17 onto the photoconductor. With the latent 18 image on the photoconductor, the next station 19 in line is the developer cleaner station 60.
; 20 Developer cleaner sta~ion 60 is conventional.
21- For example, the developer cleaner station 22 is analogous to the developer cleaner station 23 as disclosed in ~he above-identified U. S. Patent 24 3,637,306, entitled "Copying System Featuring Alternate Developing and Cleaning of Successive 26 Image Areas for Photoconductor" and assigned 27 to the same assignee o~ the present invention.
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-, 3~ 1 1 Referring now -to FIGURE 2, the 2 controlled means which controls the negative 3 corotron 18 of precharged station 32 is 4 disclosed. Also the control means for switching the polarity of grid structure 24 from a first potential to a second potential is 7 disclosed.
8 As was mentioned previously, negative 9 corotron 18 of precharge/transfer station 32 supplies negative ions to the photoconductor 11 in one cycle and in another cycle supplies 12 negative ions to a transfer medium (not . 13 shown). In order to supply negative ions, 14 a negative high voltage power supply 34 . 15 is connected to corotron 18. Il 16 In one embodiment of precharge/transfer . 17 station 32 the same amount of negative ions ~ 18 (negative charge) was applied to the photoconductor : 19 and the.transfer media. With this design ~ there is no need for a switching mechanism.
- 21 In an alternative embodiment, the negative 22 charge which is applied to the photoconductor `
23 and the trans-Eer media was different. This : 24 design requires a switching means analogous to he one which will be subsequently described.
26 Still re~erring to FIG~RE 2, grid 27 structure 24 functions as a limiting means .. . . .
; 28 for controlling the positive ion (positive ' ; :
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1 charge) which is deposite~ on the surface 2 of photoconductor 12 from scorotron 22. Tne 3 resultlng photoconductor voltage is a strong 4 function of the grid voltage. In order S to effectuate this limiting or controlling 6 function, a switching means is operably 7 connected to the grid for switching its 8 voltage between two (or more) levels.
9 Switching means 36 comprises a diode 38 hereinaf~er called unidirectional 11 device 38. One terminal of the unidirectional 12 device is connected to grid 24 while the 13 other terminal is connected to positive 14 terminal 40 hereinafter called third reference voltage source 40. Third reference voltage 16 source 40 may be any positive value, negative 17 value or ground. For example, in ~he prQferred 18 embodiment of this inven~ion the value was 19 ground.
' ResistQr 42 hereinafter called 21 third resistor means 42 connects third reference 22 voltage source 40 to a lower or equal potential.
23 In the preferred embodiment of this invention, 24 the low potential is ground. Likewise, another resistor 44 herainafter called second 26 resistor means 44 connects third referenae 27 vol~age mean~ 40 to a higher potential.
28 In the preferred embodiment o~ the invention, , .
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1 the higher potential was chosen to be 120 2 volts.
3 In an alternate embodiment of 4 the invention, third reference voltage source 40 was connected to a switchable preclean level 6 suppl~. The preclean level supply can be 7 adjusted to one of a plurality of voltage 8 potentials. For example, typical voltage 9 levels would be ~100 volts to -100 volts or ground.
11 Reference voltage source 46 hereinaftar 12 called first reference voltage source 46 13 is positioned in parallel with third reference 14 voltage source 40. The potential of first reference voltage source 46 is negative.
16 In the preferred embodiment of this invention, 17 a 1000 volts negative potential was chosen.
18 First reference voltage source 46 was established 19 by a conventional bank of neon tubes 48.
Of course, it would be obvious to one skilled 21 in the art to substitute conventional devices 22 to establish first reference voltage source 46 23 without departing from the scope of this 24 invention.
Resistor 50 hereinafter called 26 first resistor means 50 is connected in 27 series with first reference volta~e source 46 ` 28 ~so as to establish second voltage source 52.
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1 In -the preferred embodiment of this invention, 2 source 52 is chosen to be 1500 volts negative.
3 In an alternate embodiment, second voltage 4 source 52 was connected to a negative grid supply means. The negative grid supply means has a typical value of approximately 7 -1500 volts. Switching means 54 interconnects 8 unidirectional device 38 and first reference 9 voltage source 46. The connection is such that by activating switching means 54 either 11 the voltage at third reference voltage source 40 12 or the voltage at first reference voltage 13 means 46 is rendered operative. Of course, 14 several conventional switching devices may be used for switching means 54 ! However, 16 in the preferred embodiment of this invention, 17 switching means 54 was a high voltage read 18 relay switch. Positive high vol-tage supply 58 19 supplies power to scorotron 22 via terminal 56.
This completes the detailed description 21 of the preferred embodiment of -the invention.
- 22 In the preferred embodiment, high 23 voltage corona supplies 34 and 54 are current 24 regulated so that they deliver a constant total current to the corona emission wires.
~l 26 Operation 27 In describing the operation of 28 the two-cycle process, the position of the , , .
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1 processing station in relation with rotating cylindrical drum 12 will be equated with positions on the face of a clock (see FIGURES 1 and 3).
In operation, cylindrical drum 12 rotates in the direction shown by arrow 16. During the first cycle of the two-cycle process, step lA
occurs at 6:00. At 6:00, the precharge/transfer constant current nega-tive corona unit 18 of precharge/transfer station 32 will precharge the photoconductor of cylindrical drum 12 to a rough negative voltage.
For example, the overcharge voltage is -1300 volts.
The second step lB occurs at 11:00 where the final charge/preclean scorotron 22 of final charge/preclean station 20 reduces the photocon- `
ductor charge to approximately -800 volts as controlled by grid 24. At 2:00 step 2 occurs; lamp 28 of interimage station 26 performs the inter-image erase. At 3:00, step 3 occurs; the photoconductor is imaged at image station 30, such that the photoconductor charge i~ a black image is approximately -720 volts, the photoconductor charge in a gray image is approximately -400 volts, and the erase background and white charge is from -170 to -200 volts.
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1 At approximately ~:00 step 4 occurs;
2 the latent image is developed by magnetic 3 brush 58 of developer/cleaner station 60.
4 The bias of magnetic brush 58 is approximately -300 volts. Thus, magnetic brush 58 is 6 positive relative to the latent image and 7 negative relative to the erased background.
8 This completes the first drum cycle.
9 - At 6:00 during the second drum cycle step 5 occurs; transfer media 62 is 11 gated so that it moves between the corona 12 and the drum. Negative corotron 18 of precharge/
13 transfer station 3? provides the electrostatic 14 force causing the toned image on cyclindrical drum 12 to be transferxecl to transfer media 62.
- 16 The transfer media for example, paper, is 17 held against drum 12 by electrostatic force ; 18 only. In one embodiment of the invention, 19 the same corotron current setting was used for both precharge and transfer functions 21 so that switching the current level was 22 not necessary except at the end of a multi-23 copy run when the unit must be turned oEf .!
~ 24 for the final clean cycle. Of course, one.
- 25 alternative embodiment would be to switch 26 the current setting depending on whether 27 the precharge function or the transfer function 28 was being performed.
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1 ~t approximately 11:00 during the second drum cycle step 6 occurs;
switching means 36 switches grid 2~ so that the voltage from third re-ference source 40 appears on the photoconductor surface of rotating drum 12 so that the charge on said drum is reduced to a voltage near ground.
This change in voltage accomplishes the preclean function.
At approximately 1:00 step 7 occurs, lamp 28 of interimage station 26 is energized to illuminate the entire photoconductor surface of rota-ting drum 12 which changes the voltage to approximately O volts. This is an optional step and may be eliminated because of the improved con- -trol of the preclean photoconductor voltage achieved with the gridded preclean corona unit. At 3:00 during the second cycle, imaging station 30 may be on or off. The photoconductor then rotates to developer/
cleaner station 60 where`magnetic brush 58 removes residual toner from the photoconductor surface. This completes the two-cycle process. ~-This unique configuration as described above has distinct advantages ~ -over prior art configurations, in that the requirement of high voltage ferro switching in short time intervals is eliminated. In addition, the combination of the two corona units ... .... -B09-74-OSO _ 19 _ : ~ .
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2e~39 1 requires one less power supply and one less corona unit for a sizable cost reduction.
Another advantage of this configuration is the fact that the trans-fer corona unit can be made smaller than would have been possible if the combined charge and transfer corona units had been used. This is important in that significant reduction in the overall machine dimension is achieved.
While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the in-vention.
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7 To enable the development of the 8 latent image on the photoconductor and the g transferring of said latent image to a trans-ferring media, several stations are arranged 11 in proximity to and to cooperate with the 12 photoconductor to perform certain functions.
13 At the charging station, the photoconductor - 14 is charged negatively. rrhe photoconductor then moves to the exposing or imaging station 16 where a latent image-is copied from an original.
17 Next, the electrostatic :Latent image is 18 developed at a developer s~ation to form 19 a t~ner image on the photoconductor. The ; 20 toner image is then transferred from the photoconductor to another media at ~he transferring 22 station. To complete the cycle~ the photoconductor - 23 is erased, precleaned, and cleaned and is 24 then ready for another cycle.
Although the prior art electrophotographic 26 devices function adequately for the intended 27 purpose, several problems plague the systems.
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1 Probably one of the pressing problems is the Fact that the charging, transferring and precleaning functions are all performed by separate corona units at separate stations. With this type of prior art design, the cost of the electrophotographic device is relatively high, due to the individual cost of each corona unit. Since the general trend is to minimize the cost of electrophotographic devices without sacrificing efficiency, any reduction in the number of component counts in the prior art devices will be welcome.
Another problem relating to the separate processing station is the fact that each of the separate corona units require a separate power supply. The aggregate cost of these power supplies further augments the overall cost of the unit. As such, any reduction in the number of power supplies will result in cost reduction oF the unit.
It is common knowledge, that conventional electrophotographic devices may be either a single cycle process or a two-cycle process. In the typi-cal two-cycle process, the photoconductor is charged, imaged and developed during the first cyclei while the image is transferred and the photo-conductor is cleaned in the .
B09-74-050 _ 3 _ 3 ~
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1 second cycle. For satisfactory op~rations, 2 some of the stations which render necessary 3 functions during the copying process are 4 active during the first cycle, while others are inactive and vice versa. On account 6 of the rapid speed at which the photoconductor 7 would access each of the stations, it is 8 therefore necessary for high speed switching 9 to occur at these stations. The conventional 60 cycle power supply which is used for 11 supplying power to these stations cannot 12 withstand high speed switching, With these 13 drawbacks, it is clear that a more efficie~t 14 device is needed.
Several attempts have been made 16 to improve the prior art electrophotographi¢
17 devices by solving some of the above-identified `~
18 problems. For example, attempts have been 19 made to combine the charge and the transfer corona station. At first blush, this combination 21 seems to be workable and logical; since i 22 the function of both stations is to supply 23 negative charges. However, the combination 24 instead of solving the above described problems creates additional problems.
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26 One of the additional problems 27 stem from the fact that the combined charge 28 transfer station is designed with a grid . . ..
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1 structure to enhance the charge operation. However, transferring media which is fed into the machine at the charge/transfer station for trans-ferring the latent image from the photoconductor jams into the grid wires. This jam results in machine breakdown.
For proper operation, a negative charge has to be deposited onto the transferring media so that the positively charged toner particles will be attracted. With the presence of the grid assembly in the com-bined charge/transfer station, the negative charge cannot be uniformly distributed onto the transfer media. With an uneven distribution of charges, the quality of the final copy is less than satisfactory.
Objects of the Invention It is, therefore, the object of the invention to design a more efficient, low cost electrophotographic device than has heretoFor been possible.
It is another object of the present invention to build an electro-photographic device with fewer corona units than has heretofor been possible.
It is a Further object of this invention to combine the preclean and charge corona units into a single unit.
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1 It is still a further object of the present invention to use the transfer corona station to render the precharging and the transferring functions.
~ummary of the Invention The present invention overcomes the aforementioned drawbacks in the prior art by means of a unique structural combination of processing stations within the copying process. More specifically, the invention discloses a unique two-cycle process for an electrophotographic copying device. In one feature of the invention during the first cycle, the photoconductor is overcharged to a first polarity by the combined pre- -charge transfer corona unit (Corotron), the overcharge is then reduced by an opposite polarity combined chargejpreclean corona unit (Scorotron).
Imaging and developing also occurs during this first cycle.
During the second cycle, the toned image is transferred to the transferring media using the same precharge transfer corona unit (Corotron).
Following transfer, the drum is charged by the charge/preclean corona unit to a second potential for cleaning. In order to place the second charge level or potential on the photoconductor drum, ,. .
B09-74-~50 - 6 -1~1J19Z63~
1 the grid of the charge/preclean corona unit is switched to a different voltage (either the same or opposite polarity or ground as required to obtain best cleaning). The drum is then (optionally) erased by the erase lamp, and cleaned by the developer.
In another feature of the invention, the photoconductor is over-charged by a first or auxilliary corona unit at a precharged station.
The charge is then reduced to a uniform value by a second corona unit of opposite polarity at a final charge station. The photoconductor is then ready for imaging and developing.
In another feature of the invention, the photoconductor is charged to a very uniform negative value by means of a positive final charge corona unit which yields more uniform emission than a negative corona -unit.
Another feature of the invention is the use of a gridded corona unit (Scorotron~. to perform the preclean function. The increased control of the preclean photoconductor voltage because of the grid structure may eliminate the need for the preclean erase lamp function.
The improved cleaning action has reduced the hole and electron carrier intensities in the photoconductor which also reduces the fatigue effects of the photoconductor.
~:
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The foregoing and other objects, features and advantages of the invention will be apparent From the following more particular descrip-tion of the preferred embodiment of the invention, as illustrated in the accompanying drawings.
Brief Description of the Drawings FIGURES 1 and 3 are a schematic diagram of a two-cycle process electrophotographic machine showing a plurality of processing stations which incorporates the present invention.
FIGURE 2 is a schematic diagram showing the control circuit which changes the voltage of the control grid in the combined charge/preclean station.
Detailed Description ` The term corotron as used in this application means a type of corona unit having either limited or no grid structure. In effect the corotron may be cons;dered analogous to a current source.
The term scorotron as used in this application means a type of corona unit having a grid structure. The scorotron may be considered as a voltage source.
For explanation purposes, the photoconductor in the preferred embodiment B09-74-050 _ 8 _ ..
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1 of the present invention will be described 2 as a rota~ing drum. Elowever, this should 3 not be cons-trued as a limitation on the 4 scope of the invention; since it is well known in the art to design a pho-toconductor having a different shape, size and mechanical 7 configuration. For example, the photo-8 conductor may be a continuous belt or a plate 9 rather than a rotating drum structure.
Although the preferred embodiment 11 of the invention is described in association 12 with a two-cycle copying process, this should 13 be interpreted as only illustrative rather 14 than restrictive, since it would be obvious for one skilled in the art to modify the 16 inventive feature as disclosed hereinafter 17 to malse said concept operable in a one-cycle 18 copying process.
19 Referring now to FIGURE lf a pictorial view of an electrophotographic copying system 21 10 which embodies the present invention 22 is shown. A cylindrical drum 12 herein-23 after called a photoconductor is mounted 24 for rotation on shaft 14 and having on its ouker periphery a photoconductive insulating 26 layer which contains an organic ox inorganic 27 photoconductor material. The drum 12 is i Z8 ro~ated to bring the photoconductive layer ,, '. ~.
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1 -to various stations associa-ted with the 2 electrophot'ographic process; each of said 3 stations being positioned in proximity to 4 the rotating drum.
A negative corotron 18 is positioned 6 within the orbit of cylindrical drum 12 7 to define the so-called precharge/transfer 8 station 32. Negative corotron 18 of the 9 precharge/transfer station serves two functions, namely: to deposit an excess of negative 11 ions on the surface of the photoconductor 12 (for example, -1300 volts) and to deposit 13 negative ions-on a transferring media, for 14 example, paper so as to transEer a latent - 15 toner image from the surEace ofl the photoconductor.
16 As will be explained subsequently, the negative 17 charge which is deposited on the photoconductor ' 18 by nega~ive corotron 18 is rough; i.e., 19 the charge is unevenly distxibuted on the ' surface of the photoconductor.
21 After precharge/transfer station 22 32, the next sta-tion in'order is the combined 23 final charge/preclean station 20. Finally, 24 charge/preclean station 20 is the facility which supplies the final charge to the surface 26 of the photoconductor'and renders the preclean 27 function. This final charge is referred 28 to as smooth due to the fact that the charge ` ' .
: . .
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1 is evenly distributed over the surface of the photoconductor because of the cut-off characteristic produced by the control grid. As will be explained subsequently5 the polarity of the emission wires in the final charge/preclean corona is opposite to the voltage applied to the precharge/transfer corona unit. In the preferred embodiment, a posi-tive emission voltage is used so that positive ions are generated.
Final charge/preclean station 20 comprises a positive scorotron 22.
Scorotron 22 supplies positive ions at station 20. The positive ions reduce the rough charge on the photoconductor surface to a smooth charge.
Grid structure 24 is positioned between scorotron 22 and the photocon-ductor 12. The function of grid structure 24 is to control the flow of positive ions which are deposited on photoconductor 12 and hence, the resulting photoconductor voltage.
As will be expl~ined subsequently, and as shown in FIGURE 2, a switching circuit is connected to grid 24 to control the voltage on the grid. For example, in one instance the voltage on the gris is very negative (approximately -700 volts), while in another instance the grid is slightly positive ';' ' :
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l~D~63~ 1 1 (approximately +50 volts). Still in another 2 ins-tance, the voltage may be slightly negative 3 (approximately -50 volts) or ground.
4 The other station in order is the so-called interimage 26. The interimage 6 stati~n comprises high intensity lamp 28 7 and the function is to erase images on the 8 sides of the photoconductor depending on 9 the size of the document to be copied. During the second cycle, this lamp can be option-11 ally turned on to erase the photoconductor 12 to aid in the cleaning process.
13 The next station in order is the 14 image station 30. Imàge station 30 COmpriSQS
a conventional optical system Ihich functions 16 to transfer a latent image of a document 17 onto the photoconductor. With the latent 18 image on the photoconductor, the next station 19 in line is the developer cleaner station 60.
; 20 Developer cleaner sta~ion 60 is conventional.
21- For example, the developer cleaner station 22 is analogous to the developer cleaner station 23 as disclosed in ~he above-identified U. S. Patent 24 3,637,306, entitled "Copying System Featuring Alternate Developing and Cleaning of Successive 26 Image Areas for Photoconductor" and assigned 27 to the same assignee o~ the present invention.
. ,. ,' ' ' . ~:
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-, 3~ 1 1 Referring now -to FIGURE 2, the 2 controlled means which controls the negative 3 corotron 18 of precharged station 32 is 4 disclosed. Also the control means for switching the polarity of grid structure 24 from a first potential to a second potential is 7 disclosed.
8 As was mentioned previously, negative 9 corotron 18 of precharge/transfer station 32 supplies negative ions to the photoconductor 11 in one cycle and in another cycle supplies 12 negative ions to a transfer medium (not . 13 shown). In order to supply negative ions, 14 a negative high voltage power supply 34 . 15 is connected to corotron 18. Il 16 In one embodiment of precharge/transfer . 17 station 32 the same amount of negative ions ~ 18 (negative charge) was applied to the photoconductor : 19 and the.transfer media. With this design ~ there is no need for a switching mechanism.
- 21 In an alternative embodiment, the negative 22 charge which is applied to the photoconductor `
23 and the trans-Eer media was different. This : 24 design requires a switching means analogous to he one which will be subsequently described.
26 Still re~erring to FIG~RE 2, grid 27 structure 24 functions as a limiting means .. . . .
; 28 for controlling the positive ion (positive ' ; :
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1 charge) which is deposite~ on the surface 2 of photoconductor 12 from scorotron 22. Tne 3 resultlng photoconductor voltage is a strong 4 function of the grid voltage. In order S to effectuate this limiting or controlling 6 function, a switching means is operably 7 connected to the grid for switching its 8 voltage between two (or more) levels.
9 Switching means 36 comprises a diode 38 hereinaf~er called unidirectional 11 device 38. One terminal of the unidirectional 12 device is connected to grid 24 while the 13 other terminal is connected to positive 14 terminal 40 hereinafter called third reference voltage source 40. Third reference voltage 16 source 40 may be any positive value, negative 17 value or ground. For example, in ~he prQferred 18 embodiment of this inven~ion the value was 19 ground.
' ResistQr 42 hereinafter called 21 third resistor means 42 connects third reference 22 voltage source 40 to a lower or equal potential.
23 In the preferred embodiment of this invention, 24 the low potential is ground. Likewise, another resistor 44 herainafter called second 26 resistor means 44 connects third referenae 27 vol~age mean~ 40 to a higher potential.
28 In the preferred embodiment o~ the invention, , .
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1 the higher potential was chosen to be 120 2 volts.
3 In an alternate embodiment of 4 the invention, third reference voltage source 40 was connected to a switchable preclean level 6 suppl~. The preclean level supply can be 7 adjusted to one of a plurality of voltage 8 potentials. For example, typical voltage 9 levels would be ~100 volts to -100 volts or ground.
11 Reference voltage source 46 hereinaftar 12 called first reference voltage source 46 13 is positioned in parallel with third reference 14 voltage source 40. The potential of first reference voltage source 46 is negative.
16 In the preferred embodiment of this invention, 17 a 1000 volts negative potential was chosen.
18 First reference voltage source 46 was established 19 by a conventional bank of neon tubes 48.
Of course, it would be obvious to one skilled 21 in the art to substitute conventional devices 22 to establish first reference voltage source 46 23 without departing from the scope of this 24 invention.
Resistor 50 hereinafter called 26 first resistor means 50 is connected in 27 series with first reference volta~e source 46 ` 28 ~so as to establish second voltage source 52.
, . ~' _ , '` ' 10 ~ Z6 3 ~ !
1 In -the preferred embodiment of this invention, 2 source 52 is chosen to be 1500 volts negative.
3 In an alternate embodiment, second voltage 4 source 52 was connected to a negative grid supply means. The negative grid supply means has a typical value of approximately 7 -1500 volts. Switching means 54 interconnects 8 unidirectional device 38 and first reference 9 voltage source 46. The connection is such that by activating switching means 54 either 11 the voltage at third reference voltage source 40 12 or the voltage at first reference voltage 13 means 46 is rendered operative. Of course, 14 several conventional switching devices may be used for switching means 54 ! However, 16 in the preferred embodiment of this invention, 17 switching means 54 was a high voltage read 18 relay switch. Positive high vol-tage supply 58 19 supplies power to scorotron 22 via terminal 56.
This completes the detailed description 21 of the preferred embodiment of -the invention.
- 22 In the preferred embodiment, high 23 voltage corona supplies 34 and 54 are current 24 regulated so that they deliver a constant total current to the corona emission wires.
~l 26 Operation 27 In describing the operation of 28 the two-cycle process, the position of the , , .
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1 processing station in relation with rotating cylindrical drum 12 will be equated with positions on the face of a clock (see FIGURES 1 and 3).
In operation, cylindrical drum 12 rotates in the direction shown by arrow 16. During the first cycle of the two-cycle process, step lA
occurs at 6:00. At 6:00, the precharge/transfer constant current nega-tive corona unit 18 of precharge/transfer station 32 will precharge the photoconductor of cylindrical drum 12 to a rough negative voltage.
For example, the overcharge voltage is -1300 volts.
The second step lB occurs at 11:00 where the final charge/preclean scorotron 22 of final charge/preclean station 20 reduces the photocon- `
ductor charge to approximately -800 volts as controlled by grid 24. At 2:00 step 2 occurs; lamp 28 of interimage station 26 performs the inter-image erase. At 3:00, step 3 occurs; the photoconductor is imaged at image station 30, such that the photoconductor charge i~ a black image is approximately -720 volts, the photoconductor charge in a gray image is approximately -400 volts, and the erase background and white charge is from -170 to -200 volts.
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1 At approximately ~:00 step 4 occurs;
2 the latent image is developed by magnetic 3 brush 58 of developer/cleaner station 60.
4 The bias of magnetic brush 58 is approximately -300 volts. Thus, magnetic brush 58 is 6 positive relative to the latent image and 7 negative relative to the erased background.
8 This completes the first drum cycle.
9 - At 6:00 during the second drum cycle step 5 occurs; transfer media 62 is 11 gated so that it moves between the corona 12 and the drum. Negative corotron 18 of precharge/
13 transfer station 3? provides the electrostatic 14 force causing the toned image on cyclindrical drum 12 to be transferxecl to transfer media 62.
- 16 The transfer media for example, paper, is 17 held against drum 12 by electrostatic force ; 18 only. In one embodiment of the invention, 19 the same corotron current setting was used for both precharge and transfer functions 21 so that switching the current level was 22 not necessary except at the end of a multi-23 copy run when the unit must be turned oEf .!
~ 24 for the final clean cycle. Of course, one.
- 25 alternative embodiment would be to switch 26 the current setting depending on whether 27 the precharge function or the transfer function 28 was being performed.
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1 ~t approximately 11:00 during the second drum cycle step 6 occurs;
switching means 36 switches grid 2~ so that the voltage from third re-ference source 40 appears on the photoconductor surface of rotating drum 12 so that the charge on said drum is reduced to a voltage near ground.
This change in voltage accomplishes the preclean function.
At approximately 1:00 step 7 occurs, lamp 28 of interimage station 26 is energized to illuminate the entire photoconductor surface of rota-ting drum 12 which changes the voltage to approximately O volts. This is an optional step and may be eliminated because of the improved con- -trol of the preclean photoconductor voltage achieved with the gridded preclean corona unit. At 3:00 during the second cycle, imaging station 30 may be on or off. The photoconductor then rotates to developer/
cleaner station 60 where`magnetic brush 58 removes residual toner from the photoconductor surface. This completes the two-cycle process. ~-This unique configuration as described above has distinct advantages ~ -over prior art configurations, in that the requirement of high voltage ferro switching in short time intervals is eliminated. In addition, the combination of the two corona units ... .... -B09-74-OSO _ 19 _ : ~ .
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2e~39 1 requires one less power supply and one less corona unit for a sizable cost reduction.
Another advantage of this configuration is the fact that the trans-fer corona unit can be made smaller than would have been possible if the combined charge and transfer corona units had been used. This is important in that significant reduction in the overall machine dimension is achieved.
While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the in-vention.
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Claims (16)
1. In an electrophotographic apparatus having a photoconductor with the customary electrophotographic facilities for charging, imaging, developing, transferring and cleaning, the improvement comprising:
a first generator means with a first polarity being positioned in proximity with the photoconductor defining a precharge/transfer station;
second generator means with an opposite polarity being positioned in proximity with the photoconductor and downstream from the first generator means for defining a final charge/preclean station, switching means operably associated with said second generator means for switching the second generator means to different voltage levels so as to preclean or final charge the photoconductor.
a first generator means with a first polarity being positioned in proximity with the photoconductor defining a precharge/transfer station;
second generator means with an opposite polarity being positioned in proximity with the photoconductor and downstream from the first generator means for defining a final charge/preclean station, switching means operably associated with said second generator means for switching the second generator means to different voltage levels so as to preclean or final charge the photoconductor.
2. The device as claimed in Claim 1 further including a first power source for supplying power of negative polarity to the first generator means.
3. The device as claimed in Claim 1 further including a second power source for supplying positive power to the second generator means.
4. The apparatus as claimed in Claim 2 wherein the first generator means is a negative corona unit generating negative charges for pre-charging the surface of the photoconductor during a first cycle of the copying process.
5. The apparatus as claimed in Claim 4 wherein the negative corona unit generates charges for charging a transfer media during a second cycle to transfer latent image from the photoconductor to the said transfer media.
6. The device as claimed in Claim 1 wherein the second generator means comprises:
a positive corona unit;
a control grid structure being positioned between the positive corona unit and the photoconductor, the combined corona unit and grid structure being operable to charge the photoconductor to a final charge during the first cycle of the copying process.
a positive corona unit;
a control grid structure being positioned between the positive corona unit and the photoconductor, the combined corona unit and grid structure being operable to charge the photoconductor to a final charge during the first cycle of the copying process.
7. The device as claimed in Claim 6 wherein the combined corona unit and grid structure charges the photoconductor to a charge different from said final charge during the second cycle, said voltage being of opposite polarity or of the same polarity to the polarity which was placed on the photoconductor during the first cycle.
8. The device as claimed in Claim 1 wherein the switching means comprises:
a first reference voltage source;
a first resistor means being connected in series with the first voltage source to establish a second voltage source;
a third reference voltage source, positioned in parallel with the first reference source, having a polarity opposite to that of the first reference source;
a second resistor means interconnected to said third reference voltage source so as to create a voltage drop between the third re-ference voltage source and a higher voltage supply source;
a third resistor means interconnected to said third reference source and a lower potential source;
a unidirectional device connected to said third reference voltage source;
and a switching means interconnecting the unidirectional device and the first reference voltage source so that by activating said switching means either the third reference voltage source or the first reference voltage means is rendered functional.
a first reference voltage source;
a first resistor means being connected in series with the first voltage source to establish a second voltage source;
a third reference voltage source, positioned in parallel with the first reference source, having a polarity opposite to that of the first reference source;
a second resistor means interconnected to said third reference voltage source so as to create a voltage drop between the third re-ference voltage source and a higher voltage supply source;
a third resistor means interconnected to said third reference source and a lower potential source;
a unidirectional device connected to said third reference voltage source;
and a switching means interconnecting the unidirectional device and the first reference voltage source so that by activating said switching means either the third reference voltage source or the first reference voltage means is rendered functional.
9. The device as claimed in Claim 8 wherein the unidirectional device is a diode.
10. The device as claimed in Claim 8 wherein the switching means is a high voltage read relay.
11. In a recycling electrophotographic copying apparatus device for controlling the voltage on the combined charge/preclean station comprising:
a first reference voltage source;
a first resistor means being connected in series with the first voltage source to establish a second voltage source;
a third reference voltage source positioned in parallel with the first reference source having a polarity opposite to that of the first reference source;
a second resistor means interconnected to said third reference voltage source so as to create a voltage drop between the third reference voltage source and a higher voltage supply source;
a third resistor means interconnected to said third reference source and a lower potential source;
a unidirectional device connected to said third reference voltage source;
and a switching means interconnecting the unidirectional device and the first reference voltage source so that by activating said switching means either the third reference voltage source or the first reference voltage source is rendered operative.
a first reference voltage source;
a first resistor means being connected in series with the first voltage source to establish a second voltage source;
a third reference voltage source positioned in parallel with the first reference source having a polarity opposite to that of the first reference source;
a second resistor means interconnected to said third reference voltage source so as to create a voltage drop between the third reference voltage source and a higher voltage supply source;
a third resistor means interconnected to said third reference source and a lower potential source;
a unidirectional device connected to said third reference voltage source;
and a switching means interconnecting the unidirectional device and the first reference voltage source so that by activating said switching means either the third reference voltage source or the first reference voltage source is rendered operative.
12. In a recycling electrophotographic copying apparatus device for controlling the voltage on the combined charge/preclean station comprising:
first reference voltage source for supplying a reference voltage;
negative grid supply means for supplying a negative voltage resistive means interconnecting said first reference voltage source and the supply means;
preclean level supply means having a plurality of switchable voltage levels;
unidirectional means operably connected to said preclean supply means;
and a switching means interconnecting the unidirectional device and the first reference voltage source so that by activating said switching means either the preclean level supply means or the first reference voltage source is rendered operative.
first reference voltage source for supplying a reference voltage;
negative grid supply means for supplying a negative voltage resistive means interconnecting said first reference voltage source and the supply means;
preclean level supply means having a plurality of switchable voltage levels;
unidirectional means operably connected to said preclean supply means;
and a switching means interconnecting the unidirectional device and the first reference voltage source so that by activating said switching means either the preclean level supply means or the first reference voltage source is rendered operative.
13. In an electrophotographic copying apparatus wherein a photoconductor is charged, imaged, developed, transferred and cleaned, the improvement comprising:
a combined precharge/transfer generator for supplying a first charge to the photoconductor;
first voltage means operably connected to said precharge/transfer generator;
a combined final charge/preclean generator for supplying a second charge to the photoconductor;
second voltage means operably connected to the final charge/preclean generator for supplying a predetermined charge; and means operably connected for controlling the voltage on the final charge/precharge generator.
a combined precharge/transfer generator for supplying a first charge to the photoconductor;
first voltage means operably connected to said precharge/transfer generator;
a combined final charge/preclean generator for supplying a second charge to the photoconductor;
second voltage means operably connected to the final charge/preclean generator for supplying a predetermined charge; and means operably connected for controlling the voltage on the final charge/precharge generator.
14. The electrophotographic device as claimed in Claim 13 further including a photoconductor positioned in proximity with the combined precharge/transfer generator and the combined final charge/preclean generator.
15. In an electrophotographic copying apparatus wherein a photoconductor is charged, imaged, developed, transferred and cleaned, the improvement comprising:
a first electrostatic generator of a first polarity cooperating with said photoconductor to define a precharge/transfer station;
a second electrostatic generator of an opposite polarity cooperating with said photoconductor to define a final-charge/
preclean-charge station at a position downstream from said precharge/transfer station;
imaging means cooperating with said photoconductor to define an imaging station at a position downstream from said final-charge/preclean-charge station;
a (magnetic brush) developer providing toner (of said opposite polarity and) cooperating with said photoconductor to define a developing/
cleaning station at a position downstream from said imaging station;
control means operable during a first cycle of said photoconductor to deposit a charge of said first polarity on said photoconductor as it passes said precharge/transfer station, to thereafter reduce the charge of said first polarity to a lower magnitude as said photoconductor passes said final-charge/preclean-charge station, to thereafter image said photoconductor to form a latent electrostatic image (of said first polarity) as said photoconductor passes said imaging station, and to thereafter deposit toner (of said opposite polarity) upon said latent image as said photoconductor passes said developing/cleaning station;
and control means operable during a second cycle of said photoconductor to supply a transfer medium to said transfer station and to charge the same to said first polarity to effect transfer of said toner thereto as said photoconductor passes said precharge/transfer station, to thereafter subject said photoconductor and residual toner to a charge of said opposite polarity as said photoconductor passes said final-charge/preclean-charge station, and to thereafter clean the residual toner from said photoconductor as said photoconductor passes said developing/
cleaning station during said second cycle.
a first electrostatic generator of a first polarity cooperating with said photoconductor to define a precharge/transfer station;
a second electrostatic generator of an opposite polarity cooperating with said photoconductor to define a final-charge/
preclean-charge station at a position downstream from said precharge/transfer station;
imaging means cooperating with said photoconductor to define an imaging station at a position downstream from said final-charge/preclean-charge station;
a (magnetic brush) developer providing toner (of said opposite polarity and) cooperating with said photoconductor to define a developing/
cleaning station at a position downstream from said imaging station;
control means operable during a first cycle of said photoconductor to deposit a charge of said first polarity on said photoconductor as it passes said precharge/transfer station, to thereafter reduce the charge of said first polarity to a lower magnitude as said photoconductor passes said final-charge/preclean-charge station, to thereafter image said photoconductor to form a latent electrostatic image (of said first polarity) as said photoconductor passes said imaging station, and to thereafter deposit toner (of said opposite polarity) upon said latent image as said photoconductor passes said developing/cleaning station;
and control means operable during a second cycle of said photoconductor to supply a transfer medium to said transfer station and to charge the same to said first polarity to effect transfer of said toner thereto as said photoconductor passes said precharge/transfer station, to thereafter subject said photoconductor and residual toner to a charge of said opposite polarity as said photoconductor passes said final-charge/preclean-charge station, and to thereafter clean the residual toner from said photoconductor as said photoconductor passes said developing/
cleaning station during said second cycle.
16. An electrophotographic apparatus having a photoconductor which is charged, imaged, developed, transferred and cleaned, the improvement comprising:
a first generator means positioned in proximity with the photoconductor;
said first generator means having a first polarity to deposit excess ions on the surface of said photoconductor;
a second generator means operably associated with said photoconductor;
said second generator means having a second polarity opposite to that of the first to smooth or reduce the excess ions on the surface of the photoconductor;
image means operably associated with the photoconductor to image a latent print of a document onto said photoconductor;
developer means operably associated with said photoconductor for developing the latent print;
transfer means operably associated with the photoconductor to transfer the latent print to a suitable media; and cleaning means for cleaning the surface of said photoconductor.
a first generator means positioned in proximity with the photoconductor;
said first generator means having a first polarity to deposit excess ions on the surface of said photoconductor;
a second generator means operably associated with said photoconductor;
said second generator means having a second polarity opposite to that of the first to smooth or reduce the excess ions on the surface of the photoconductor;
image means operably associated with the photoconductor to image a latent print of a document onto said photoconductor;
developer means operably associated with said photoconductor for developing the latent print;
transfer means operably associated with the photoconductor to transfer the latent print to a suitable media; and cleaning means for cleaning the surface of said photoconductor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58064375A | 1975-05-27 | 1975-05-27 | |
| US580,643 | 1975-05-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1092639A true CA1092639A (en) | 1980-12-30 |
Family
ID=24321916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250,130A Expired CA1092639A (en) | 1975-05-27 | 1976-04-13 | Photoconductor charging technique |
Country Status (14)
| Country | Link |
|---|---|
| JP (2) | JPS51144631A (en) |
| AU (1) | AU500168B2 (en) |
| BE (1) | BE840962A (en) |
| BR (1) | BR7603386A (en) |
| CA (1) | CA1092639A (en) |
| CH (1) | CH591715A5 (en) |
| DE (1) | DE2611499C3 (en) |
| ES (1) | ES448216A1 (en) |
| FR (1) | FR2312805A1 (en) |
| GB (1) | GB1496473A (en) |
| IT (1) | IT1064166B (en) |
| NL (1) | NL7604315A (en) |
| SE (1) | SE418540B (en) |
| SU (1) | SU619124A3 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1535398A (en) * | 1975-06-13 | 1978-12-13 | Tokyo Shibaura Electric Co | Electrostatic copying apparatus |
| US4133610A (en) * | 1977-12-30 | 1979-01-09 | International Business Machines Corporation | Optimum preclean corona current for eliminating the accumulation of contaminants from developers |
| JPS58193571A (en) * | 1982-05-07 | 1983-11-11 | Fuji Xerox Co Ltd | Destaticizer of copying machine |
| JPH0642115B2 (en) * | 1984-06-18 | 1994-06-01 | 富士ゼロックス株式会社 | Cleaning device for electrophotographic copying machine |
-
1976
- 1976-03-18 DE DE2611499A patent/DE2611499C3/en not_active Expired
- 1976-03-23 IT IT21447/76A patent/IT1064166B/en active
- 1976-04-01 FR FR7610160A patent/FR2312805A1/en active Granted
- 1976-04-09 GB GB14642/76A patent/GB1496473A/en not_active Expired
- 1976-04-13 CA CA250,130A patent/CA1092639A/en not_active Expired
- 1976-04-21 BE BE166335A patent/BE840962A/en not_active IP Right Cessation
- 1976-04-23 NL NL7604315A patent/NL7604315A/en not_active Application Discontinuation
- 1976-04-28 CH CH532176A patent/CH591715A5/xx not_active IP Right Cessation
- 1976-04-30 JP JP51048715A patent/JPS51144631A/en active Granted
- 1976-05-05 SE SE7605133A patent/SE418540B/en unknown
- 1976-05-18 SU SU762359443A patent/SU619124A3/en active
- 1976-05-25 ES ES448216A patent/ES448216A1/en not_active Expired
- 1976-05-27 BR BR3386/76A patent/BR7603386A/en unknown
- 1976-05-27 AU AU14379/76A patent/AU500168B2/en not_active Expired
-
1979
- 1979-06-22 JP JP7828679A patent/JPS5522788A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FR2312805A1 (en) | 1976-12-24 |
| AU1437976A (en) | 1977-12-01 |
| DE2611499C3 (en) | 1980-06-04 |
| CH591715A5 (en) | 1977-09-30 |
| IT1064166B (en) | 1985-02-18 |
| JPS5522788A (en) | 1980-02-18 |
| SE7605133L (en) | 1976-11-28 |
| SU619124A3 (en) | 1978-08-05 |
| GB1496473A (en) | 1977-12-30 |
| SE418540B (en) | 1981-06-09 |
| FR2312805B1 (en) | 1978-11-17 |
| JPS556230B2 (en) | 1980-02-14 |
| ES448216A1 (en) | 1977-07-01 |
| JPS51144631A (en) | 1976-12-11 |
| AU500168B2 (en) | 1979-05-10 |
| BR7603386A (en) | 1976-12-21 |
| DE2611499A1 (en) | 1976-12-16 |
| NL7604315A (en) | 1976-11-30 |
| BE840962A (en) | 1976-08-16 |
| DE2611499B2 (en) | 1979-09-20 |
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