Patent Application
20050158069
This disclosure relates to a developer housing, and more particularly, to a seal for a magnetic developer housing.
In the process of electrophotographic printing, a photoconductive member is uniformly charged and exposed to a light image of an original document. Exposure of the photoconductive member records an electrostatic latent image corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles attracted from the carrier granules to form a toner powder image on the photoconductive member that corresponds to the informational areas contained within the original document. This toner powder image is subsequently transferred to a copy sheet and permanently affixed thereto in image configuration.
In electrophotographic printing machines, magnetic rolls are frequently employed in the developing station and the cleaning station. Typically, the magnetic roll includes a stationary magnet having a rotating tube positioned concentrically thereabout. At the developer station, a developer material of magnetic carrier granules having toner particles adhering triboelectrically thereto is attracted to the tube by the magnetic field generated by the magnetic roll. The tube surface is usually roughened so that the frictional force between the developer material and the tube causes the developer material to rotate with the tube. The developer material is advanced by the tube to a position closely adjacent the electrostatic latent image recorded on the photoconductive member. At the cleaning station, a layer of carrier granules adheres to the tube and moves therewith. As the layer of carrier granules pass closely adjacent to the photoconductive member, residual toner particles are attracted to the layer of carrier granules and move therewith away from the photoconductive member. In this way, residual toner particles are cleaned from the photoconductive member. A copier employing a magnetic roll is shown in U.S. Pat. No. 4,823,102 issued Apr. 18, 1989 to Abraham Cherian et al.
It is critical for performance of the printer that the developer housing in which the magnetic roll is supported is sealed with respect to the magnetic roll in order to prevent toner from escaping into the insides of the printer. This has been accomplished in the past, but with excessive cost. For example, rare earth magnetic seals have been used successfully, but they are too expensive. Felt seals have been used to seal the magnetic roll to the developer housing, however, they present installation, adhesive shelf life, component contamination from adhesives, ineffective adhesives and ineffective adhesive problems which allow the magnetic roll to spin in the seal out of position with respect to the photoconductive member.
Obviously, there is still a need, in magnetic developer housings for an inexpensive magnetic roll seal.
Accordingly, a device for sealing a magnetic roll to a developer housing is disclosed that answers the above-mentioned problem by including a plastic retainer having side walls that are spring loaded with a felt seal positioned within the said walls. The spring loaded side walls of the plastic retainer hold the felt seals in place to facilitate installation onto the magnetic rolls.
The foregoing and other features of this disclosure will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which like reference numerals refer to like elements and wherein:
While this disclosure will be described hereinafter in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
For a general understanding of the features of the present disclosure, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements.
Referring to
Initially, a portion of the photoconductive surface passes through charging station A. At charging station A, a corona generating device indicated generally by the reference numeral 22 charges the photoconductive belt 10 to a relatively high, substantially uniform potential.
At an exposure station, B, a controller or electronic subsystem (ESS), indicated generally by reference numeral 29, receives the image signals representing the desired output image and processes these signals to convert them to a continuous tone or grayscale rendition of the image which is transmitted to a modulated output generator, for example the raster output scanner (ROS), indicated generally by reference numeral 30. Preferably, ESS 29 is a self-contained, dedicated minicomputer. The image signals transmitted to ESS 29 may originate from a RIS as described above or from a computer, thereby enabling the electrophotographic printing machine to serve as a remotely located printer for one or more computers. Alternatively, the printer may serve as a dedicated printer for a high-speed computer. The signals from ESS 29, corresponding to the continuous tone image desired to be reproduced by the printing machine, are transmitted to ROS 30. ROS 30 includes a laser with rotating polygon mirror blocks. The ROS will expose the photoconductive belt to record an electrostatic latent image thereon corresponding to the continuous tone image received from ESS 29. As an alternative, ROS 30 may employ a linear array of light emitting diodes (LEDs) arranged to illuminate the charged portion of photoconductive belt 10 on a raster-by-raster basis.
After the electrostatic latent image has been recorded on photoconductive surface 12, belt 10 advances the latent image to a magnetic development unit 38 that includes a housing 40 at station C, where toner is electrostatically attracted to the latent image using commonly known techniques. The latent image attracts toner particles from the carrier granules forming a toner powder image thereon.
With continued reference to
Fusing station F includes a fuser assembly indicated generally by the reference numeral 70 which permanently affixes the transferred toner powder image to the copy sheet. Preferably, fuser assembly 70 includes a heated fuser roller 72 and a pressure roller 74 with the powder image on the copy sheet contacting fuser roller 72. The pressure roller is cammed against the fuser roller to provide the necessary pressure to fix the toner powder image to the copy sheet. The fuser roll is internally heated by a quartz lamp (not shown). Release agent, stored in a reservoir (not shown), is pumped to a metering roll (not shown). A trim blade (not shown) trims off the excess release agent. The release agent transfers to a donor roll (not shown) and then to the fuser roll 72.
The sheet then passes through fuser 70 where the image is permanently fixed or fused to the sheet. After passing through fuser 70, a gate 80 either allows the sheet to move directly via output 84 to a finisher of stacker, or deflects the sheet into the duplex path 100, specifically, first into single sheet inverter 82 here. That is, if the sheet is either a simplex sheet or a completed duplex sheet having both side one and side two images formed thereon, the sheet will be conveyed via gate 80 directly to output 84. However, if the sheet is being duplexed and is then only printed with a side one image, the gate 80 will be positioned to deflect that sheet into the inverter 82 and into the duplex loop path 100, where that sheet will be inverted and then fed to acceleration nip 102 and belt transport 110, for recirculation back through transport station D and fuser 70 for receiving and permanently fixing the side two image to the backside of that duplex sheet, before it exits via exit path 84.
After the print sheet is separated from photoconductive surface 12 of belt 10, the residual toner/developer and paper fiber particles adhering to photoconductive surface 12 are removed therefrom at cleaning station E. Cleaning station E includes a rotatably mounted fibrous brush in contact with photoconductive surface 12 to disturb and remove paper fibers and a cleaning blade to remove the non-transferred toner particles. The blade may be configured in either a wiper or doctor position depending on the application. Subsequent to cleaning, a discharge lamp (not shown) floods photoconductive surface 12 with light to dissipate any residual electrostatic charge remaining thereon prior to the charging thereof for the next successive imaging cycle.
Plastic toner retainer seal 90 that is used to prevent toner from escaping through the ends of magnetic roll 45 and to minimize installation of magnetic roll onto the toner retainer seal, as shown in
It should now be understood that an improved, less expensive, spring loaded plastic toner seal retainer has been disclosed that prevents toner from escaping through the ends of magnetic rolls positioned to receive toner from a magnetic developer housing. A felt seal is retained within the plastic retainer by spring action that is provided by the plastic retainer.
While the invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined herein.
