Patent Application
20080061499
Various of the above-mentioned and further features and advantages will be apparent to those skilled in the art from the specific apparatus and its operation or methods described in the example(s) below, and the claims. Thus, they will be better understood from this description of these specific embodiment(s), including the drawing figures (which are approximately to scale) wherein:
While the present disclosure will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the disclosure 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 disclosure 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.
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, a 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 development station C, where toner, in the form of liquid or dry particles, is electrostatically attracted the latent image using commonly known techniques. The latent image attracts toner particles from the carrier granules forming a toner powder image thereon. As successive electrostatic latent images are developed, toner particles are depleted from the developer material. A toner particle dispenser, indicated generally by the reference numeral 39, dispenses toner particles into developer housing 40 of developer unit 38.
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 roll 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 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 or 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 transports 110, for recirculation back through transfer 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.
The various machine functions are regulated by controller 29. The controller is preferably a programmable microprocessor, which controls all of the machine functions hereinbefore described. The controller provides a comparison count of the copy sheets, the number of documents being recirculated, the number of copy sheets selected by the operator, time delays, jam corrections, etc. The control of all of the exemplary systems heretofore described may be accomplished by conventional control switch inputs from the printing machine consoles selected by the operator. Conventional sheet path sensors or switches may be utilized to keep track of the position of the document and the copy sheets.
In accordance with an aspect of the present disclosure as shown in
Carriage 200 in
In
In
outer nip idlers 163 and 165 make contact because actuator arm is now positioned between upstanding arms 220 and 222 of carriage 200. Continued movement of actuator 190 as shown in
A diagram of the correction of skew with devices that allow a sheet to pivot and translate, pivot only and translate only is shown in
In operation, the pre-registration idlers are engaged and the translating carriage assembly including the drive roll and center nip idler assembly is locked in a central fixed location in the lateral direction for initial sheet transport up to the stalled roll registration nip(s). This is done by use of a solenoid that positions and locks the carriage through a V groove and provides nip loading to the outer drive nips. This maintains accurate position control of the sheet for delivery to registration. After the sheet arrives at the stalled roll registration roll and starts to form a buckle for deskew, the solenoid is released thereby releasing the outer pre-registration idlers and freeing the carriage. The body of the sheet is then free to pivot about the narrow sole center drive nip and translate in the lateral direction to self align itself with the registration roll (allowing the tail to wag). The buckle formation is maintained by the center pre-registration drive nip to provide sufficient lead edge force at the registration nip prior to roll engagement and then provides drive isolation through transfer with nearly all differential buckle and associated sheet stress eliminated, thus resulting in greatly increased media deskew latitude and improved sheet motion quality through transfer across all media sizes and weights.
It should now be understood that a method and apparatus for relieving the differential buckle strain in a sheet once the lead edge of the sheet has arrived at a stalled roll registration nip and buckle formation and the deskew process has begun and includes a segmented pre-registration drive roll assembly with nip release for outer nips mounted on a releasable low friction lateral translation carriage.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
