Patent Application
20050214026
This invention generally relates to image-forming systems having a corona charger. More particularly, this invention relates to electrophotographic reproduction systems with a corona charger for electrostatically charging a photoconductor.
An electrophotographic reproduction system is used to transfer images onto paper or other medium. The electrophotographic reproduction system may be a copier, duplicator, printer, or the like. The images may be analog or digital. The electrophotographic reproduction system typically has a photoconductor, which may have a drum, belt, or other configuration. A belt-type photoconductor usually forms a continuous loop and is mounted on rollers for movement through the electrophotographic reproduction system. A drum-type photoconductor usually forms a cylindrical shape that is mounted on one or more rollers or another device to rotate on its axis in the electrophotographic reproduction system. A photoconductor typically has a photosensitive film layer covering an electrically conductive layer. There may be intermediate layers between the film and conductive layers. The photoconductor usually moves past or through a charging device, an exposure machine, a development station, a transfer mechanism, and a cleaning station. The electrophotographic reproduction system also may have a logic control unit (LCU) or other microprocessor, a graphic user interface, and other components.
As the photoconductor moves through the electrophotographic reproduction system, the charging device electrostatically charges a frame or portion of the photoconductor surface. The exposure machine optically exposes or projects an image onto the frame with the charged surface to form an electrostatic latent image on the photoconductor. The photoconductor moves the electrostatic latent image through the development station, which deposits toner onto the photoconductor. The toner is also is electrostatically charged and thus adheres to the oppositely-charged portions of the electrostatic latent image on the photoconductor. The photoconductor moves the resulting toner image through the transfer mechanism, where the toner image is transferred onto a sheet of paper or other medium. The paper subsequently passes through a fuser device prior to exiting the electrophotographic reproduction system. The fuser device affixes the toner to the sheet using elevated temperature and pressure. The photoconductor is refreshed at the cleaning station in preparation for the next image transfer. The cleaning station removes residual toner and electrostatic charges from the photoconductor.
Many electrophotographic reproduction systems use a corona charger to electrostatically charge the surface of the photoconductor. A corona charger usually has one or more wires positioned in a housing adjacent to the photoconductor. Each wire is held under tension by support members. Multiple wires usually are positioned parallel to each other on separate support members. When a high voltage potential is applied to the wires, a corona or ion field is generated around the wires. The corona causes current to flow to the photoconductor, thus depositing an electrostatic charge on the surface of the photoconductor. The wires may be configured and positioned to deposit a substantially uniform charge on the photoconductor.
The corona charger typically is integrated within a charger assembly for the electrophotographic reproduction system. The charger assembly usually includes other components for operation of the corona charger such as electrical circuitry, controls, and the like. The corona charger also may have a shield, a ground plane, and a grid electrode. The shield partially surrounds the wires without obstructing the area between the wires and the photoconductor. The shield usually is made of an electrically insulative material. The ground plane typically is positioned on the side of the wires that is opposite the photoconductor. The ground plane usually is made of an electrically conductive material. The ground plane may have an applied electrical bias or may be grounded. The grid electrode is positioned between the wires and the photoconductor. The grid electrode may be a conductive plate or sheet with slits or holes such as a mesh, a screen, or the like. The grid electrode also may be a plurality or network of wires. A bias voltage usually is applied to the grid electrode. The bias voltage creates an electric field to control the current flow between the wires and the photo conductor.
With repeated operation of the electrophotographic reproduction system, the wires in the corona charger may deteriorate and may become contaminated. The deterioration and contamination may increase the non-uniformity of the electrostatic charge on the photoconductor beyond acceptable levels for image quality. The deterioration and contamination also may affect the voltage applied to the wires. In addition, the deterioration and contamination may cause corona discharges.
The wires in a corona charger usually are replaced on a frequent basis to avoid or address the affects of deterioration and/or contamination. For some electrophotographic reproduction systems, the charger assembly is discarded and a new charger assembly installed when the wires become or are near to becoming deteriorated or contaminated. The installation of a new charger assembly may increase operating costs, especially in larger or more sophisticated electrophotographic reproduction systems. Operators also may delay the installation of the new charger assembly to avoid the expense. This delay may cause additional maintenance, reduce system durability, and affect image quality.
For other electrophotographic reproduction systems, the individual wires in the corona charger are replaced when the wires become or are near to becoming deteriorated or contaminated. Wire replacement typically is time consuming and results in longer downtime for the electrophotographic reproduction system. Wire replacement usually is done better by a service technician or someone with like experience and/or training. Each wire is physically handled. The old wires are removed from the support members. The new wires are attached to the support members. The new wires may attract contaminants from an installer's hands. In addition, the tension in each wire must be accurately set. The tension controls the vibration frequency of the wires. A change in the vibration frequency may affect image quality and may cause electrical discharges form the corona charger. If there is insufficient tension, the wire may sag and come close enough to cause an electrical discharge to the photoconductor or other components in the electrophotographic reproduction system. If there is too much tension, the wire may break when installed or during later operation of the electrophotographic reproduction system. After the new wires are installed on the support members, the corona charger may need to be installed and aligned properly with the photoconductor. The charger assembly may require additional adjustments.
This invention provides a charging mechanism for an electrophotographic reproduction system. The charging mechanism has multiple facets, each with a corona charger. The charging mechanism may be repositioned to expose the corona chargers of multiple facets to a photoconductor.
An electrophotographic reproduction system may have a charging mechanism and a photoconductor. The charging mechanism may have a charger sleeve and a charger cartridge. The charger sleeve forms a channel with an aperture positioned adjacent to the photoconductor. The charger cartridge has a first facet and a second facet. The first facet has a first corona charger disposed thereon. The second facet has a second corona charger disposed thereon. The charger cartridge is positioned within the channel of the charger sleeve. The first facet faces the aperture. The charger cartridge may be repositioned in the channel to have the second facet face the aperture.
A charging mechanism for an electrophotographic reproduction system may have a charger sleeve and a charger cartridge. The charger sleeve forms a channel with an aperture. The charger cartridge has at least two facets. Each facet has a corona charger disposed thereon. The charger cartridge is positioned within the channel of the charger sleeve. One facet faces the aperture. The charger cartridge may be repositioned in the channel to have another facet face the aperture.
In a method for electrophotographically reproducing images, a first electrostatic charge is generated on a photoconductor by a first corona charger on a first facet of a charger cartridge in a multifaceted charging mechanism. An image is projected onto the photoconductor. Toner is deposited onto the photoconductor. The toner image is transferred onto a medium. The charger cartridge is repositioned in a charger sleeve of the multifaceted charging mechanism. A second electrostatic charge is generated on a photoconductor by a second corona charger on the second facet of the charger cartridge in the multifaceted charging mechanism.
Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims.
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.
The charger cartridge 116 has multiple facets that have a corona charger. There may be two facets arranged in a rectangular configuration. There may be three facets arranged in a triangular configuration. There may be four facets arranged in a square configuration. The charger cartridge 116 may have other multiples of facets and other configurations. The charger cartridge 116 may have other facets or sides that do not have a corona charger. Each corona charger is electrically isolated from the other corona chargers on the charger cartridge 116. When the charger cartridge 116 is inserted in the charger sleeve 118, the facet facing the photoconductor 104 may be physically isolated from the other facets to reduce or eliminate dust and other contaminants from reaching the other corona chargers. The physical isolation may be formed by a substantially air-tight seal, a substantially dust-free seal, a mechanical interface, or the like between the facets. The physical isolation also may be formed or enhanced by maintaining a higher air pressure next to the facets that are not facing the photoconductor.
In operation, the photoconductor 104 moves through the electrophotographic reproduction system 100 on rollers 106. The multifaceted charger mechanism 102 electrostatically charges a frame or portion on the surface of the photoconductor 104. The exposure machine 108 optically exposes or projects an image onto the photoconductor 104, causing an electrostatic latent image to form on the frame with the charged surface. The photoconductor 104 moves the electrostatic latent image through the development station 110, which deposits toner onto the electrostatic image. The toner is electrostatically charged and thus adheres to the oppositely-charged portions of the electrostatic latent image. The photoconductor 104 then moves the resulting toner image through the transfer mechanism 111, where a transfer roller 112 transfers the toner image onto a sheet of paper or other medium S from a supply tray 129. In the transfer mechanism 111, the paper passes through a fuser device 113 prior to exiting the electrophotographic reproduction system 100. The fuser device affixes the toner to the paper using elevated temperature and pressure. The photoconductor 104 then is refreshed at the cleaning station 114 in preparation for the next image transfer. The cleaning station 114 removes residual toner and electrostatic charges from the photoconductor 104.
Initially, the multifaceted charger mechanism 102 has a first facet of the charger cartridge 116 facing the photoconductor 104. The first facet has a first corona charger that electrostatically charges the surface of the photoconductor 104 during the reproduction of a first set of images. Subsequently, the charger cartridge 116 is repositioned in the charger sleeve 118 so that a second facet faces the photoconductor 104. The second facet has a second corona charger that electrostatically charges the surface of the photoconductor 104 during the reproduction of a second set of images. If the charger cartridge 116 has additional facets with corona chargers, the charger cartridge 116 is repositioned for the additional corona chargers to electrostatically charge the surface of the photoconductor in similar fashion during the reproduction of additional sets of images. Unless the charger cartridge 116 is replaced sooner or reused, the repositioning of the charger cartridge 116 in the charger sleeve 118 continues until all the corona chargers are used.
After one or more of the corona chargers are used, the charger cartridge 116 is removed from the charger sleeve 118. A new or reconditioned charger cartridge is installed in the charger sleeve 118. The used charger cartridge is reconditioned or discarded. The used charger cartridge may be reconditioned by a service technician or similarly trained person at a customer site, at a manufacturing or service facility for the electrophotographic system, or like places. A reconditioned charger cartridge includes charger cartridges where one or more of the wires or other components have been replaced.
To reposition or change from one facet to another facet, the charger cartridge 116 may be removed from the charger sleeve 118. The charger cartridge 116 then is rotated and reinserted into the charger sleeve 118 such that the other facet with the other corona charger is in position to electrostatically charge the photoconductor 104. The charger sleeve 118 also may be configured to rotate the charger cartridge without removing it. The change from one facet to another facet in the charger cartridge 116 may be done by other manual or mechanical devices. The change may happen in response to a signal from a logic control unit. The change may occur when the wires in a corona charger become deteriorated or contaminated. The change may occur as part of a regular or preventive maintenance program. The change may occur at any time.
The multifaceted charging mechanism 102 has an alignment mechanism 122 connected between the charger bracket 120 and the charger sleeve 118. The alignment mechanism 122 moves or places the charger sleeve 118 into essentially the same position adjacent to the photoconductor 104. The alignment mechanism 122 has a biasing latch 124, a pin 126, and bolts 128. The pin 126 connects the biasing latch 124 to the charger bracket 120. The bolts 128 slidably connect the charger sleeve 118 to the charger bracket 120. Slidably connected includes axial movement or sliding along the bolts 128. Each of the bolts 128 may have a spring device 131 mounted between the charger sleeve 118 and the charger bracket 120.
The biasing latch 124 moves the charger sleeve 118 along the bolts 128, either away from or toward the charger bracket 120. The biasing latch 124 has a lever element 123 connected to a cam element 125. The lever element 123 rotates the cam element 125 around the pin 126. The cam element 125 engages the charger sleeve 118. The cam element 125 has an irregular-shaped circumference that translates the rotational motion of the lever element 123 into a reciprocating motion of the charger sleeve 118 along the bolts 128. When the lever element 123 closes, the cam element 125 moves the charger sleeve 118 away from the charger bracket 120 thus pushing one or more guides or stops 140 against a stop bracket 127. There may be other guides or stops on the charging mechanism 122 and the electrophotographic reproduction system 100. The stop bracket 127 is mounted at a location to position the charger sleeve 118 adjacent to the photoconductor 104. The lever element 123 may be positioned to hold the charger cartridge 116 in the charger sleeve 118 when the biasing latch 124 is closed. When the lever element 123 opens, the cam element 125 releases the charger sleeve 118 from the stops and permits movement of the charger sleeve 118 along the bolts 128 toward the charger bracket 120. The biasing latch 124 may have other configurations and components including those using a spring.
When the lever element 123 is closed, the biasing latch 124 holds the charger sleeve 118 away from the charger bracket 120 and holds the stops 140 against the stop bracket 127. The location of the charger bracket 120 in the electrophotographic reproduction system 100 may be selected such that the charger sleeve 118 is adjacent to the photoconductor 104 when the lever element 123 is closed. The charger bracket 120 may maintain an essentially fixed position once the electrophotographic reproduction system 100 is assembled. The position of the charger bracket 120 may be adjusted when removed for maintenance or replacement. The position of the charger bracket 120 also may be adjusted to maintain the alignment of the charging mechanism 122 with other components in the electrophotographic reproduction system 100.
When the biasing latch 124 is closed, the charger sleeve 118 is positioned adjacent to the photoconductor 104. The charger sleeve 118 holds the charger cartridge 116 in a position where the corona charger on one facet can apply a substantially uniform electrostatic charge across the surface of the photoconductor 104. When the biasing latch 124 is opened, the charger sleeve 118 may be moved away from the photoconductor 104 to change the facet of charger cartridge 116. After the facet is changed, the biasing latch 124 is closed. The charger sleeve 118 returns to essentially the same position as prior to the change. The new facet and corona charger are in essentially the same positions as the old facet and corona charger before the change. Similarly, the new corona charger can apply a substantially uniform electrostatic charge across the surface of a photoconductor 104.
The charger sleeve 118 may have one or more alignment posts 146 and a contact post 147 on the inside of the channel 130. The alignment posts 146 interface with notches on the charger cartridge 116. The alignment posts 146 align and hold the charger cartridge 116 within the channel 130. The alignment posts may be made of an insulative material. The contact post 147 is positioned inside the channel 130 along the side of the cartridge sleeve 118 facing the photoconductor. The contact post 147 has a post electrical contact that interfaces with a notch on the facet of the charger cartridge 116 facing the photoconductor. This interface completes the electrical connection for applying a voltage potential to the wires in the corona charger on the facet facing the photoconductor 104.
The first corona charger 152 has first wires 154, first support members 156, and a first base electrode or ground plane 158. There may be one or more first wires 154. Each of the first wires 154 is held in tension between a pair of the first support members 156. The tension in the first wires 154 may be provided by machine winding of the wires on the first support members 156. The tension in the first wires 154 may be provided by one or more springs connected to the first wires 152 on the first support members 156. The first wires 154 may be formed by a continuous wire or by individual wires spanning the first support members 156. The first wires 154 may be electrically connected through the first support members to electrical contacts in a notch on the facet holding the corona charger. The first wires 154 are suspended above the first base electrode 158. The first wires 154 and the first base electrode 156 may be connected to electrical and control circuitry and controls (not shown) located in the charger bracket 120.
The second corona charger 162 has second wires 164, second support members 166, and a second base electrode or ground plane 168. There may be one or more second wires 164. Each of the second wires 164 is held in tension between a pair of the second support members 166. The tension in the second wires 164 may be provided by machine winding of the wires on the second support members 166. The tension in the second wires 164 may be provided by one or more springs connected to the second wires 162 on the second support members 166. The second wires 164 may be formed by a continuous wire or by individual wires spanning the second support members 166. The second wires 164 may be electrically connected through the second support members to electrical contacts in a notch on the facet holding the corona charger. The second wires 164 are suspended above the second base electrode 168. The second wires 164 and the second base electrode 166 may be connected to electrical and control circuitry and controls (not shown) located in the charger bracket 120.
The charger cartridge 116 has a front section 170, a back section 172, and a base 175. The front section 170 is connected to a handle 176. The back section 172 and base 175 may form one or more notches 174 for each facet with a corona charger.
The notches 174 receive the alignment posts 146 and the contact post 147 when the charger cartridge 116 is inserted into the charger sleeve 118. Each notch 174 has a notch electrical contact that can interface with the post electrical contact on the contact post 147. The notch electrical contacts may be connected to a power or voltage supply and electrical circuitry and controls. The post electrical contact interfaces with the notch electrical contact on the facet facing the photoconductor 104 when the charger cartridge 116 is inserted into the charger sleeve 118. This interface provides an electrical connection for applying a high voltage potential to the wires of the corona charger on the facet facing the photoconductor 104. The other notches 174 interface with the alignment posts 146, which may prevent electrical connections to the corona chargers on facets not facing the photoconductor 104. When the charger cartridge 116 is repositioned, the notch 174 that was connected to the contact post 147 now connects to an alignment post 146. Similarly, the notch 174 of the new facet now facing the photoconductor 104 now connects with the contact post 147. A high voltage potential may be applied to the wires of the corona charger on the new facet facing the photoconductor 104.
The first support members 156 and the first base electrode 158 are disposed on one side of the base 175. The second support members 166 and the second base electrode 168 are disposed on the other side of the base 175. The base 175 may be made of an electrically insulative material. The base 175 may have an electrically insulating layer between the first base electrode 158 and the second base electrode 168. The base 175 may have a plurality of holes 178 to assist airflow in the charger sleeve 118. The charger cartridge 116 may have a cartridge grid electrode, which may be in addition to or instead of the grid electrode 144 in the charger sleeve 118.
When assembled, the front section 170 of the charger cartridge 116 may be disposed within the opening 136 in the front side 138 of the charger sleeve 118. The front section 170 of the charger cartridge 116 may be disposed adjacent or against the front side 138 of the charger sleeve 118. The front section 170 and the front side 138 may form a substantially air tight seal. The front section 170 and the front side 138 may form a substantially dust-free seal where air may pass, but where dust and other particles do not pass. The front section 170 and front side 138 may be connected, but not form any seal. The sleeve charger 118 may have a positive pressure from an air supply, fan, or the like.
When the charger cartridge 116 is removed from the charger sleeve 118, the charger sleeve 118 may remain adjacent to the photoconductor 104 and may remain connected to the charger bracket 120 in the electrophotographic reproduction system. The charger cartridge 116 may be repositioned to expose another facet and corresponding corona charger through the aperture 132 to the photoconductor 104. The repositioning may include removing, rotating, and reinserting the charger cartridge. The repositioning may include rotating the charger cartridge in place. The charger cartridge 116 may be replaced by a new charger cartridge. The old charger cartridge may be reconditioned by a service technician, at the factory, or the like. Reconditioning would include the replacement of the wires and other components as needed.
While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that other embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.
This is a 111A application of U.S. Provisional Application Ser. No. 60/553,741, filed Mar. 17, 2004, entitled “ELECTROPHOTOGRAPHIC REPRODUCTION SYSTEM WITH A MULTIFACETED CHARGING MECHANISM” by Daniel R. Palmer, et al.
| Number | Date | Country | |
|---|---|---|---|
| 60553741 | Mar 2004 | US |
