Patent Application
20090304419
The present disclosure pertains to fusers and methods for stripping printed paper or media or media sheets from a fusing member.
Typically, in an electro-photographic reproduction machine, toner is permanently fixed to the substrate via means of a fusing subsystem. This subsystem can have many different architecture types. Pressure fixing involves applying pressure and heat for sufficient time to melt and flow the toner into the substrate. The pressure can be formed by roll pairs, belts, and many combinations thereof. Traditionally silicone or Viton with a layer of silicone oil on the surface as a release layer are materials of choice for high speed pressure fusing on cut sheet equipment.
In recent years, there has been more and more usage of silicone members with a Teflon overcoat as the release surface. Once the paper has the material effectively fused, the paper must be removed from the fuse member. This is typically done either by direct mechanical means, such as stripping fingers, or by indirect methods such as creep (strain based) stripping or air stripping. In recent studies it was determined that when stripping with an air knife, the optimal conditions for stripping uncoated paper were different than those for coated paper. Furthermore, it was found that optimal conditions for acquiring a lead edge were different than the optimal conditions for effectively stripping the body of a sheet. When referring to optimal conditions, the primary parameters of interest are referred to as phi which defines an angle made between an orifice at the air knife and a tangent to the roll at an impingement point; theta defining an angle from the nip exit to the impingement point about the fuse member radius; d defining distance from the orifice exit to the impingement point along an orifice axis; and air pressure in the plenum prior to exiting the orifice at the air knife.
According to aspects of the embodiments, there is provided a method of optimizing an electro-photographic reproduction machine having a fusing subsystem and an air knife. The methods acquire at least one electro-photographic reproduction machine objective and media characteristic; and the acquired objective and characteristic are used to determine values for the pressurized air emitted from the air knife, the position of the air knife, and the rotation of the air knife relative to a fuse roll in the fusing subsystem. The methods further disclose acquiring the leading edge of the media being stripped and then using the beam strength of the media to assist in stripping the body of the sheet. The air knife can be controlled by a controller or a processor based on determined optimization parameter values that relate to objectives and media characteristics.
Aspects of the disclosed embodiments relate to methods for optimizing an electro-photographic reproduction machine, and corresponding apparatus and systems. The disclosed embodiment proposes the optimization of parameters of an air knife between jobs and within sheets. Specifically, theta and phi are parameters that would be desired to change for coated vs. uncoated media and for body stripping vs. lead edge acquisition. Due to geometry concerns, the distance (d) of the air knife from a fuse roll may also be adjusted as theta and phi are adjusted. Due to down stream handoffs and to other geometry considerations, theta, phi, and “d” would also need to be adjusted to not only optimize for the different conditions, but also maintain integrity of paper path handoffs.
The disclosed embodiments include methods for optimizing an electro-photographic reproduction machine that has a fusing subsystem comprising a fuse roll and a pressure roll to form a nip through which media passes and an air knife having an orifice directing a stream of pressurized air at an impingement point on the fuse roll. After acquiring the electro-photographic machine objectives, e.g. body stripping vs. lead edge acquisition, and media characteristics, e.g. coated vs. uncoated paper, a set of optimization parameters determined. The determined optimization parameters can include rotation of theta, phi, and adjustment of “d” as needed for optimal performance of a particular media being stripped for a given pressure.
The disclosed embodiments further include an apparatus or system for acquiring the electro-photographic machine objectives and media characteristics to determine a set of optimization parameters. The determined optimization parameters can be employed by a controller or processor to rotate, position, and regulate the stream of pressurized air being emitted by the air knife.
The term “electro-photographic printing machine,” “reproduction apparatus,” or “printer” as used herein broadly encompasses various printers, copiers or multifunction machines or systems, xerographic or otherwise, unless otherwise defined in a claim. The term “media” herein refers to a physical sheet of paper, plastic, or other suitable physical substrate for images, whether precut or web fed. Also media refers to different types of print media with different media characteristics, such as thickness, roughness, moisture content, etc. A “copy sheet” may be abbreviated as a “copy” or called a “hardcopy.”
A second exposure/imaging is performed by imaging device 38 that comprises a laser based output structure and is utilized for selectively discharging the photoreceptor on toned areas and/or bare areas, pursuant to the image to be developed with the second color toner. At this point, the photoreceptor contains toned and untoned areas at relatively high voltage levels and toned and untoned areas at relatively low voltage levels. These low voltage areas represent image areas which are developed using discharged area development (DAD). To this end, a negatively charged, developer material 40 comprising color toner is employed. The toner, which by way of example may be yellow, is contained in a developer housing structure 42 disposed at a second developer station D and is presented to the latent images on the photoreceptor by way of a second HJD system. A power supply (not shown) serves to electrically bias the developer structure to a level effective to develop the discharged image areas with negatively charged yellow toner particles 40.
Subsequent to image development a sheet of support material 52 is moved into contact with the toner images at transfer station G. The sheet of support material is advanced to transfer station G by a sheet feeding apparatus to the pretransfer device which directs the advancing sheet of support material into contact with photoconductive surface of belt 10 in a timed sequence so that the toner powder image developed thereon contacts the advancing sheet of support material at transfer station G. Transfer station G includes a transfer dicorotron 54 which sprays positive ions onto the backside of sheet 52. This attracts the negatively charged toner powder images from the belt 10 to sheet 52. A detack dicorotron 56 is provided for facilitating stripping of the sheets from the belt 10.
After transfer, the sheet continues to move, in the direction of arrow 58, onto a conveyor (not shown) which advances the sheet to fusing station H or fusing subsystem. Fusing subsystem includes a fuser assembly, indicated generally by the reference numeral 60, which permanently affixes the transferred powder image to sheet 52. The fuser assembly 60 comprises a heated fuser roller 62 and a backup or pressure roller 64. Sheet 52 passes between fuser roller 62 and backup roller 64 with the toner powder image contacting fuser roller 62. In this manner, the toner powder images are permanently affixed to sheet 52 after it is allowed to cool. After fusing, the sheet is separated from the fuser roll by an air knife, described in more detail below, to a chute which guides the advancing sheets 52 to a catch tray for subsequent removal from the printing machine by the operator. An air knife 250 provides a stream of air to assist in separating the fused sheet from the heated fuser roll. With lighter weight sheets with a heavy toner image near the lead edge 152 of the sheet, the sheet sometimes might either not separate from the fuser or, due to the lack of beam strength of the sheet, might retack to the fuser roll and cause a jam. Air knife 250 can be controlled by controller data acquisition (CDA) 110. CDA 110 controls air knife 250 by rotation, displacement, and by regulating the stream of pressurized air being emitted from the nozzle.
After the sheet of support material is separated from photoconductive surface of belt 10, the residual toner particles carried by the non-image areas on the photoconductive surface are removed therefrom. These particles are removed at cleaning station I using a cleaning brush structure contained in a housing 66.
The air knife 250 includes a nozzle or orifice for emitting a stream 260 of pressurized air. The orifice of the air knife forms a coordinate with the impingement point that is tangent to the circumference of fuse roll 220. The impingement point and the stream of pressurized air from the air knife form a first angle, “phi” (φ). The nip and the impingement point form a second angle, “theta” (θ). The nozzle or orifice of the air knife 250 is positioned at a given distance, “d”, from the impingement point. It should be noted that a pneumatic means (not shown) with air stream regulating means can be employed to regulate aspects such as volume, pressure, direction of the pressurized air 270. It should be noted that the air knife 250 could be rotated around its own axis and can be displaced away or towards the impingement point on the circumference of the fuse roll.
In action 630, optimization parameters are determined for the desired situation or job being performed by electro-photographic reproduction machine 100. In action 630, a response value is calculated to determine the rotation, distance, or pressure to set air knife 250 where the response value would be maximized. Once the parameters have been determined control passes to action 640 for further processing.
In action 640, the optimized parameters are implemented to position the air knife 250 at the desired rotation, at the desired distance, and the desired pressure to operate the air knife at optimal performance. The rotation, distance, and pressure could be set manually by an operator or by the use of a controller such as CDA 110.
In action 740, the optimization parameter are determined from the acquired objectives 710, acquired leading edge 730 data, and acquired media characteristics. Once the parameters have been determined control passes to action 750 for further processing.
In action 750 the air knife 250 is controlled based on the determined optimization parameters. With the acquisition of leading edge 730 the knife pressure can be shut off or reduced so the beam strength of the paper 230 could be used to assist in stripping the body of the sheet. Using the strength of the paper for stripping reduces power losses and potential gloss defects.
When considering changes to air knife parameters in some cases it may be desirable to have only one parameter change such as theta (θ), but more likely multiple ones have to be changed simultaneously. This may necessitate multiple actuators or more complex linkages/camming mechanisms, but the design of these actuators will be specific to the architecture of the fuser subsystem 300 and is routine engineering. It should be noted that some architectures if manually actuated, i.e. for paper type will likely have discrete positions, whereas architectures that change are automatically actuated could be continuous.
Embodiments within the scope of the present invention may also include computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or combination thereof) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of the computer-readable media.
Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, objects, components, and data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps.
Although the above description may contain specific details, they should not be construed as limiting the claims in any way. Other configurations of the described embodiments of the invention are part of the scope of this invention. For example, the principles of the invention may be applied to each individual user where each user may individually deploy such a system. This enables each user to utilize the benefits of the invention even if any one of the large number of possible applications do not need the functionality described herein. In other words, there may be multiple instances of the devices in
