Patent Grant
11604424
The following references, the disclosures of which are incorporated herein in their entireties by reference, are mentioned:
US Pat. No. 8,005,410 B2, issued Aug. 2, 2011, entitled POLYIMIDE INTERMEDIATE TRANSFER COMPONENTS, by Wu, describes an intermediate transfer belt that includes a thermosetting polyimide.
US Pub. No. 20200356029A1, published Nov. 12, 2020, entitled BELT, INTERMEDIATE TRANSFER BELT, AND IMAGE FORMING APPARATUS, by Takei, et al., describes a belt which includes a polyimide-based resin with carbon black particles in an outer layer.
US Pub. No. 20040114969A1, published Jun. 17, 2004, entitled DEVELOPMENT SYSTEM, by Manno, describes a development system including a magnetic developer roll including a rotatable sleeve having located therein a rotatable magnetic core, and a developer material delivery system for providing a metered supply of developer material to the rotatable sleeve.
The exemplary embodiment relates to electrophotographic printing and finds particular application in connection with a development system with developer belts of variable length.
The process of electrophotographic printing generally includes charging a surface of a photoconductive member, such as a belt or drum, to a substantially uniform potential to sensitize the surface thereof. The charged portion of the photoconductive surface is exposed to a light image from either a scanning laser beam, an LED source, or an original document being reproduced. This records an electrostatic latent image on the photoconductive surface. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed. Two-component and single-component developer materials are commonly used for development. A typical two-component developer comprises magnetic carrier granules having toner particles tribo-electrically charged and adhering thereto. A single-component developer material typically comprises toner particles. Toner particles are attracted to the latent image, forming a toner powder image on the photoconductive surface. The toner powder image is subsequently transferred to a sheet of print media, either directly, or via an intermediate transfer member. Finally, the toner powder image is heated to fuse it more permanently to the print media sheet in image configuration.
In many development systems, a magnetic roller (“mag roll”) is used to transfer toner particles from a developer housing to the photoconductive surface. To allow a number of development systems to be positioned around the photoconductive member or intermediate transfer member, each development system is configured slightly differently so that the mag roll can contact the photoconductive member. The development systems are thus not interchangeable. Additionally, replacing the toner containers is not always easy since they are not in alignment with each other. These factors tend to increase downtime of the printing device and add cost to the printing device.
There remains a need for an interchangeable development system which is capable of use in more than one position relative to a photoconductive surface.
In accordance with one aspect of the exemplary embodiment, a development system includes a housing configured for accommodating a developer material which includes toner particles. At least one magnetic roller within the housing attracts the developer material to a surface thereof. A continuous developer belt attracts the toner particles from the at least one magnetic roller to a surface of the developer belt. A plurality of developer rollers carry the developer belt around them. One of the rollers is positioned adjacent to an associated image transfer member, whereby some of the toner particles are transferred to a latent image formed on the image transfer member.
In accordance with another aspect of the exemplary embodiment, a marking device includes a plurality of the development systems as described above.
In accordance with another aspect of the exemplary embodiment, a printer includes the marking device as described above and a sheet transport system which conveys associated sheets of print media through the marking device to receive toner image layers from the image transfer member.
In accordance with another aspect of the exemplary embodiment, a method of printing includes providing a first developer material in a first housing, the first developer material including first toner particles, transferring some of the first toner particles to a first continuous developer belt, developing a first latent image on a first image transfer member with some of the transferred toner particles to form a first toner image layer, and transferring the first toner image layer to a sheet of print media.
In accordance with another aspect of the exemplary embodiment, a printer includes a print media source, a marking device, which receives print media from the print media source and applies toner images to the print media, The marking device includes an image transport member, at least one charging station, which charges a photoconductive surface of the image transport member, an exposure station, which forms a latent image on the charged photoconductive surface, at least one development system, and a sheet transport system which conveys a sheet of the print media from the print media source to the marking device to receive a toner image layer from the image transfer member. Each development system includes a housing configured for accommodating a developer material which includes toner particles, a continuous developer belt which carries the toner particles from the housing to the surface of the image transfer member to develop the latent image on the image transfer member to form the toner image.
Aspects of the exemplary embodiment relate to a development system incorporating a developer belt, to a marking device incorporating the development system, and to a method of printing which can be performed with the system.
As explained in further detail below, the exemplary system helps to optimize space usage, part commonality, and development latitude in an electrophotographic printer.
In one embodiment, the marking device includes two or more development systems.
In one embodiment, two or more development systems incorporate developer belts of different lengths.
In one embodiment, each developer belt receives toner particles from (at least) two magnetic rollers in contact with the developer belt or sufficiently closely positioned to allow toner particles to pass therebetween.
In one embodiment, each developer belt transfers toner to a latent image formed on a surface of an image transfer member at a single transfer nip. This can provide flexibility in the positioning of the development system.
In one embodiment, the marking device includes at least two identical (universal, interchangeable) development systems.
In one embodiment, the marking device includes at least two development systems which are mirror images of each other.
In one embodiment, the marking device includes at least two vertically-stacked development systems.
In one embodiment, the marking device includes at least two horizontally-aligned development systems.
In one embodiment, the marking device includes at least eight or at least ten development systems.
In one embodiment, the marking device is used in a method of printing.
As used herein, a “printing device” or “printer” can include any device for rendering an image on print media, such as a copier, laser printer, bookmaking machine, or a multifunction device (which includes one or more additional functions such as scanning, archiving, emailing, and/or faxing).
“Print media” can be a usually flimsy physical sheet of paper, plastic, or other suitable physical print media substrate for images. A “print job” or “document” is normally a set of related sheets, usually one or more collated copy sets copied from a set of original print job sheets or electronic document page images, from a particular user, or otherwise related.
A “digital image” generally may include information in electronic form which is to be rendered on the print media by the printing device and may include text, graphics, pictures, and the like. The operation of applying toner images to print media, for example, graphics, text, photographs, etc., is generally referred to herein as printing or marking.
With reference to
With reference also to
The developer belt 14A may have a length, in the continuous direction, of at least 4 cm, or at least 6 cm, or at least 8 cm, or up to 100 cm, or up to 50 cm. A width of the developer belt 14A, perpendicular to the length, may be a function of the width (in the cross process direction) of the image transport member 16, e.g., equal to or slightly less than the width of the image transport member 16. The thickness (smallest dimension) of the developer belt 14A may be at least 0.5 mm, or at least 1 mm, or up to 1 cm. Other developer belts 14B, etc. in the marking device 10 generally have the same thickness and width, although the length(s) may be different.
The developer rollers 18, 20, 22 may be of the same diameter or of different diameters. For example, the roller 22 which contacts the transfer member 16 may be larger in diameter than the other developer rollers 18, 20, e.g., at least 10% larger, or at least 20% larger, or at least 40% larger, or up to 100% larger. For example, developer rollers 18, 20 may each have a diameter of 4 to 12 mm, and developer roller 22 a diameter of 7 to 20 mm.
The development system 12A includes a developer housing 30, which holds a supply of a dry developer material, such as magnetic carrier granules having toner particles tribo-electrically charged and adhering thereto. The developer belt 14A is partially enclosed within the housing 30. One or more magnetic rollers (“mag rolls”) 32, 34 (two mag rolls in the illustrated embodiment) is/are mounted in the housing 30. The mag rolls may be larger, in diameter, than the developer rollers 18, 20, 22. Respective development nips 36, 38 are defined between each mag roll and the developer belt 14A. In one embodiment, each mag roll 32, 34 includes a cylindrical shell or sleeve 40, 42, which is rotatable around a magnetic core 44, 46 containing a set of magnets. Alternatively, the shell 40, 42 is stationary while the core 44, 46 rotates. The shell may be formed of an electrically conductive, non-ferrous material, such as aluminum or stainless steel. In other embodiments, a magnetizable brush (not shown) takes the place of each cylindrical shell. The developer material (including the toner particles and magnetic carrier) is attracted to the mag rolls 32, 34 by magnetic forces. The toner particles are then attracted from the mag rolls to the developer belt 14A by a potential difference between the mag roll and the developer belt 14A. In particular, the toner particles are transferred from the mag roll 32, 34 to first portion 24 of the developer belt 14A at the development nip 36, 38, leaving the carrier granules behind in the developer housing 30. The developer belt 14A and the image transfer member 16 define a single transfer nip 50 between them.
The toner particles are attracted to the image transfer member 16 by a potential difference between the developer belt 14A and a surface 52 of the image transfer member 16. In the illustrated embodiment, the surface 52 is photoconductive and the toner particles are used to develop a latent image formed on the photoconductive surface 52. In particular, each development system 12 has an associated charging station 54, such as a charging corotron, which charges the photoconductive surface 52, and an exposure station 56, which forms the latent image on the photoconductive surface. The toner particles are electrostatically attracted to the latent image to form a toner image layer on the surface 52. Residual toner particles, which are not needed to form the toner image layer, may return on the developer belt 14A to the developer housing 30 to be reused.
In contrast to the image transfer member 16, the developer belt 14A carries toner particles (a relatively continuous layer of toner particles) but does not carry toner image layers (areas of toner particles spaced by areas of no toner particles where the image transfer member has been exposed/not exposed, respectively), since there is no associated charging station or exposure station 56 for the developer belt 14A.
The toner particles may be supplied to the housing 30 from a replaceable toner container 58A. Augers 60, 62, within the housing 30, mix the toner particles with the magnetic carrier granules. While two augurs are shown, separate augurs may be provided for mixing and for aiding pickup of developer on to the mag rolls. In some embodiments, intermediate mag rolls (not shown) may be positioned between the augers 60, 62 and mag rolls 32, 34 such that the toner concentration is higher on the mag rolls 32, 34.
The developer belt 14A exits the housing 30 through a narrow slot 64. Suction may be applied in the area of the slot to minimize the escape of developer particles. Seals may also be used to limit the escape of developer particles.
The augers 60, 62, mag rolls 32, 34, and developer rollers 18, 20, 22 may all be driven by a common drive system 24, such as a motor with suitable gears and/or belts. Alternatively, separate drive systems may be employed. The drive system 24 controls the speed of the developer rollers 18, 20, 22, such that the developer belt 14A matches or approximates the speed of the surface of the driven image transfer member 16. In other embodiments, the speeds of the developer belt and of the surface of the driven image transfer member need not closely match and, for example, may have a speed ratio of up to 1.2:1.
One advantage of the development system of
Another advantage is that the two small mag rolls 32, 34 provide two development nips 36, 38, which can provide a greater development latitude in a limited design space.
Another advantage is that the single nip 50 between the developer belt 14A and the image transfer member 16 provides flexibility in the final positioning of the developer housing 30, which allows for a universal or semi-universal (interchangeable) development system 12A. The single nip 50 also reduces or eliminates the need to align a mag roll development nip frequently. This allows various interfaces in the developer housing to be maintained in a constant relationship when moving the development housing 30 to new positions in the marking device. These interfaces may include the mag roll to auger relationships, the mix auger to pickup auger relationship (where present), and dispenser to mix auger relationship.
Another advantage is that a greater number of development systems 12A, 12B, etc., can be accommodated around a single image transfer member 16 than in a conventional marking device. For example, eight or ten development systems 12A, 12B, etc., can be installed around a drum transfer member 16 of about 84 mm in size. While in
With reference now to
The second set of interchangeable development systems 12F, 12G, 12H, 121, and 12H may each be configured as mirror images to the development systems on the first side (with Y defining the axis of symmetry of the marking device). The only difference between the five right-side development systems being the length of the developer belt 14F, 14G, etc., position of the roller 22 relative to rollers 18, 20, and possibly an adjustment to a position of the slot 64, through which the belt enters and exits the housing The belt length is selected based on the distance to the image transfer member 16.
Using different lengths of the developer belt 14A, 14B, etc. allows the development systems on each side to be stacked vertically, which can make them more accessible from adjacent sides 70, 72 of the marking device, e.g., for replacement of the toner containers 58A-J, which can also be vertically stacked.
The marking device 10 of embodiment of
While eight development systems 12A, 12B, etc., are illustrated in
While not shown, the developer housing 30 may include suitable manifolds, endcaps, electrical connections, and the like, which may be adapted to have the ability to be used in right and left side housings to provide a universal housing or substantially universal housing.
In the embodiment of
In addition to the advantages previously noted, the embodiment of
Another advantage is that the developer housings 30A-30J can be closer to the respective toner bottles 58A-58J, avoiding complex dispensing lines. This facilitates making the development system and toner container an integrated interchangeable unit.
Another advantage is that the size of the marking device enclosure 13 can be significantly reduced, as compared to existing marking devices. A 30-50% reduction in the footprint of the marking device is to be expected.
In this embodiment, each of the development systems 12A-F may be configured identically, and be horizontally aligned, allowing respective toner containers 58A-F to be accessible from an upper end 91 of the marking device enclosure.
In another embodiment, the upper, horizontal portion, of the belt 89 serves as the transport member 82 (not illustrated) 76 and corotron 80G is omitted.
While
Another advantage of various embodiments described herein is that versatility of the placement of developer housings around a drum or belt image transfer member can provide an increased color gamut and/or additional colors/coatings etc.
Returning to
Also shown in
With reference now to
In another embodiment, gear mechanisms 132, 134, 136 carried by a telescoping drive shaft may be employed, as illustrated in
The image transfer belt 16 illustrated in
In the case of a drum-shaped image transfer member 16, 16A, 16B, etc., as illustrated in
The developer belt 14A, B, C, etc. of
The image transfer member (belt or drum) may be coated with a ceramic or ceramer type coating. Ceramers are sinterable high performance polymers based on polyphenylene sulfone (PPSO2). The coating may be 0.01-5 mm thick, such as at least 0.05 mm or up to 0.3 mm in thickness. Ceramic coatings, for example, can provide 10 Megaohms/cm3 for a 0.13 mm thick ceramic coating, measured at 200 V, and a volume resistivity of 6×107 at a field of 1.5 V/micron.
With reference now to
At S102, a first developer material is provided in a first developer housing 30A of a first development system 12A, the first developer material including first toner particles.
At S104, S102 may be repeated for one or more additional development system 12B, 12C, etc.
At S106, some of the first toner particles are transferred to a first continuous developer belt 14A of the first development system 12A, e.g., by at least one magnetic roller 32, 34.
At S108, S106 may be repeated for each additional developer system.
At S110, a first latent image is formed on a first image transfer member 16, 16A.
At S112, S110 may be repeated for each additional developer system, wherein the latent image is formed on the first image transfer member 16, 16A or on an additional image transfer member 16B, 16C, etc.
At S114, the first latent image is developed on the first image transfer member with some of the toner particles transferred from the first developer belt 14A to form a first toner image layer.
At S116, S114 may be repeated for each additional developer system wherein the latent image is developed on the first image transfer member 16 or on the additional image transfer member 16B, 16C, etc., to form an additional toner image layer, on top of or spaced from the first toner image layer.
At S118, the first toner image layer is transferred from the first image transfer member to a sheet 76 of print media.
At S120, additional toner image layer(s) may be transferred from the first image transfer member 16 (or from the additional image transfer member 16B, 16C, etc., where present) to the sheet 76 of print media.
At S122, the sheet, with the toner image(s) thereon may be fused, optionally post-processed, and output.
In some embodiments, the printed sheet may be inverted and returned to the marking device for printing on a second side of the sheet, as described for S106-S122, prior to optionally being post-processed and output.
The method ends at S124.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8005410 | Wu | Aug 2011 | B2 |
| 20040114969 | Manno | Jun 2004 | A1 |
| 20200356029 | Takei et al. | Nov 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 5134869 | Jan 2013 | JP |
| Entry |
|---|
| English machine translation of Fujishima et al. (JP 5134869 B2) (Year: 2013). |
