Patent Grant
8081914
Disclosed herein is an apparatus and method that detaches media from a fuser in a printer.
Presently, fusers are used in image generation devices, such as printers, to fuse a latent image on media, such as a document, by applying pressure and heat to the image on the document. When the fused document exits the fuser, the document may stick to the fuser roll. Some devices use stripper fingers to strip the document from the fuser roll. Unfortunately, the stripper fingers can cause a mottle look on the document where the fingers contact the document when stripping it from the fuser roll.
Other devices use air knives to strip the document from the fuser roll. An air knife or a plurality of air knives strip a document from a fuser roll by blowing pressurized gas between the document and the fuser roll to strip the document at or close to a fuser roll nip. This can result in a smooth looking fused image on the document. This can also result in the document bouncing around in the air knife baffle, creating slag with the document waving or flopping around in the air knife baffle chamber.
After initially stripping the lead edge of the document off the fuser roll, the air knife system shuts off and the document self strips off the fuser roll in the air knife baffle. At this point, the striping function relies on the document stiffness to continue the self stripping. This change in stripping function changes the strip point location of the document relative to the fuser roll because part of the document re-tacks to the fuser roll. Different document strip points create image quality defects showing a visible transition in solids resulting from the air turning off. Furthermore, the document sheet may take a curved trajectory after being stripped before the lead edge is in a decurler exit nip causing the document sheet to buckle. If there is a buckle after the air knife is turned off, the sheet strip point moves away from the fuser nip, further causing image quality defects.
As mentioned, the image quality defects are evidenced by a difference between a smooth image appearance and a mottle image appearance on the document. For example, if the document is stripped closer to the fuser nip, the resulting image is smoother. If the document is stripped at a location after the nip, the resulting image has a mottle look. In documents that use coated media, the transition from smooth to mottle is especially noticeable to customers, which is evidenced by maintenance requests precipitated by image quality defect.
One approach to eliminate or limit the image quality defect is to leave the air knife on while the whole document sheet passes through the fuser. This requires a higher air knife pressure capacity, which requires a bigger compressor. Unfortunately, a bigger compressor is more costly, requires more power, requires major hardware changes, and results in higher noise levels. Furthermore, excessive use of air knives excessively cools the fuser roll. Also, excessive use of air knives cause streaks created by the air jets on some coated documents. Additionally, air knives can cause air streaks due to an interaction of air temperature and document corrugation. For example, multiple air knives blow air under the document at certain points creating ridges, but the document still sticks a bit to fuser at other points creating grooves, thus wrinkling the document.
Thus, there is a need for an improved apparatus and method that detaches media from a fuser in a printer.
An apparatus and method that detaches media from a fuser in a printer is disclosed. The method can include feeding a media sheet through a fuser member and applying gas from an air knife to the media sheet on the fuser member to detach the media sheet at a detach point from the fuser member. The method can also include asserting tension on the media sheet using a set of rotational members and continuing to apply gas from the air knife to the media sheet until the set of rotational members asserts tension on the media sheet.
In order to describe the manner in which advantages and features of the disclosure can be obtained, a more particular description of the disclosure briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the disclosure and are not therefore to be considered to be limiting of its scope, the disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
The embodiments include a method in a printing apparatus including a fuser member, an air knife, and a set of rotational members. The method can include feeding a media sheet through the fuser member. The method can also include applying gas from the air knife to the media sheet on the fuser member to detach the media sheet at a detach point from the fuser member. The method can also include asserting tension on the media sheet using the set of rotational members. The method can also include continuing to apply gas from the air knife to the media sheet until the set of rotational members asserts tension on the media sheet.
The embodiments further include apparatus useful for printing. The apparatus can include a fuser member configured to contact a media sheet to fuse marking material on the media sheet. The apparatus can also include an air knife configured to apply gas to the media sheet to detach the media sheet from the fuser member at a fuser member detach point. The apparatus can also include a set of rotational members configured to assert tension on the media sheet prior to ceasing applying gas from the air knife to the media sheet.
The embodiments further include a method in a printing apparatus including a fuser member, an air knife, and a decurler. The method can include feeding a media sheet through the fuser member. The method can also include applying gas from the air knife to the media sheet on the fuser member to detach the media sheet at a detach point from the fuser member. The method can also include receiving the media sheet at the decurler. The method can also include accelerating a rotational speed of the decurler to assert tension on the media sheet while a portion of the media sheet is still in the fuser member. The method can also include continuing to apply gas from the air knife to the media sheet until the decurler asserts tension on the media sheet. The method can also include ceasing applying gas from the air knife to the media sheet after the decurler asserts tension on the media sheet. The method can also include decelerating the rotational speed of the decurler after asserting tension on the media sheet while the media sheet is still in the fuser member.
The apparatus 100 can include an air knife 120 configured to apply gas 122 to the media sheet 140 to detach the media sheet 140 from the fuser member 110 at a fuser member detach point 146. The air knife 120 may include a fluid pathway which connects an associated source of pressurized gas. The air knife can also include at least one orifice adjacent to the fuser member 110, where the orifice can be configured to expel the pressurized gas 122 from the source of pressurized gas.
The apparatus 100 can include a set of rotational members 130 configured to assert tension on the media sheet 140 prior to ceasing applying gas 122 from the air knife 120 to the media sheet 140. The set of rotational members 130 can be a decurler 130 that can include a first decurler member 132 rotationally supported in the apparatus 100 and a second decurler member 134 rotationally supported in the apparatus 100, where the first decurler member 132 can be coupled to the second decurler member 134 at a decurler nip 136. For illustrative purposes, the embodiments will be described with respect to a decurler, but it is understood that the embodiments can use any set of rotational members, such as rotational members for an inverter, rotational members for a document stacker, rotational members dedicated to applying embodiments of this disclosure, or any other set of rotational members that can assert tension on a media sheet. For example, the decurler 130 or other rotational members can perform double duty of operating according to their traditional operation while also applying tension on the media sheet according to the disclosed embodiments. The first decurler member 132 and/or the second decurler member 134 can be a roll, a belt, or any other member that can be rotationally supported in an apparatus. The decurler 130 can be configured to assert tension on the media sheet 140 to ensure that the media sheet 140 detaches at substantially the same detach point on the fuser member 110 using the decurler 130 as the fuser member detach point 146 using the air knife 120. The air knife 120 can be configured to cease applying gas 122 to the media sheet 140 after the decurler 130 asserts tension on the media sheet 140.
The decurler 130 can be configured to assert tension by accelerating a rotational speed of the decurler 130 to assert tension on the media sheet 140 after receiving the media sheet 140 at the decurler 130 while a portion of the media sheet 140 is still in the fuser member 110. For example, the decurler rotational speed can be increased to assert media sheet tension 142 and reduce media sheet slag 144 as fast as possible. The air knife 120 can be left on until the slag 144 is reduced to make sure the media sheet 140 does not retack or restick onto the fuser member 110. The air knife 120 can shut off after the decurler 130 asserts tension on the media sheet 140. The decurler 130 can be configured to decelerate its rotational speed after asserting tension on the media sheet 140. For example, the decurler 130 can be decelerated after reducing slag to reduce wear on a decurler roll, such as the first or second decurler members 132 and 134, and/or to avoid smears or scratches on an image on the media sheet 140. The rotational speed of the decurler 130 can be reduced to a point that is slightly faster than a speed of the fuser member 110 to keep tension on and reduce slag of the media sheet 140 in an area, such as in an air knife baffle, 148 between the fuser member 110 and the decurler 130. The actual relative speeds of the fuser member 110, the decurler 130, an inverter (not shown), and other elements can be based on ratios based on geometry and operational relationships between elements of the apparatus 100 according to desired operation.
The decurler 130 can be configured to decelerate its rotational speed after asserting tension on the media sheet 140 to reduce trail edge curl of the media sheet 140. For example, if the rotational speed of the decurler 130 provides too much tension on the media sheet 140 while the media sheet 140 is still in the fuser member 110, the extra tension can cause a trail edge of the media sheet 140 to curl. Thus, the decurler 130 can maintain an appropriate tension on the media sheet 140 to maintain tension on the media sheet 140 while avoiding trail edge curl of the media sheet 140.
The decurler 130 can also be configured to accelerate its rotational after the media sheet 140 exits the fuser member 110. For example, the rotational speed of the decurler 130 can accelerate after a trail edge of the media sheet 140 exits the fuser member 110 to transfer the media sheet 140 to a next station in the apparatus 100. The decurler 130 can maintain this speed until the media sheet 140 leaves the decurler 130. The decurler 130 can also maintain this speed or reduce the speed until the lead edge of a next media sheet 140 reaches the decurler 130. The decurler 130 may operate at one accelerated speed and one decelerated speed for all operations or may operate at different accelerated and/or decelerated speeds depending on desired operation.
Gas can be applied from the air knife 120 to the media sheet 140 and tension can be asserted by the decurler 130 on the media sheet 140 while the media sheet 140 is still in the fuser member 110 to maintain constant image quality of the media sheet 140. For example, the timing of different speeds of the decurler 130 and the timing of application of gas by the air knife 120 can be set to avoid image quality defects on the media sheet 140. Thus, an image on the media sheet 140 can look better and more consistent because the media sheet 140 is detached at a consistent location 146 on the fuser member 110 relative to the fuser member nip 116.
The apparatus 110 can determine a media sheet type is subject to differential image quality defects that result from detaching the media sheet 140 from the fuser member 110 in different manners and/or at different points on the fuser member 110. Tension may be asserted on the media sheet 140 using the decurler 130 prior to ceasing applying gas 122 from the air knife 120 to the media sheet 140 only if the media sheet type is subject to differential image quality defects. For example, a decurler acceleration and deceleration profile can be run only when a user selects media that could have the defects. After selecting the media, software can control air knife solenoid pressure in order to keep the pressure on long enough until the decurler 130 eliminates the document slack. This can ensure that the document will strip at the same point on the fuser member 110. Alternately, the apparatus 100 can operate according to some embodiments without determining whether a media sheet type is subject to differential image quality defects.
Thus, a media sheet, such as a document, can be accelerated in the decurler 130 to maintain the document in tension right before the air knife 120 is turned off. By maintaining the document in tension, the document can maintain substantially the same strip point position 146 on the whole fuser member 110 and the document does not retack to the fuser member 110, which can eliminate gloss and mottle differential defects. Once the document is off the fuser member 110, the decurler 130 can reduce its speed in order to avoid any unwanted dysfunction, such as curl, on the document. For example, document trail edge curl can be a function of decurler speed. Trial edge curl can increase if decurler speed increases. Ideally, the decurler speed may be kept as slow as possible to avoid trail edge curl. Embodiments can increase decurler speed at some times to avoid image quality defects, while decreasing decurler speed at other times to avoid trail edge curl.
For example, the decurler rotational speed can be increased to reduce media sheet slag as fast as possible. The air knife can be left on until the slag is reduced to make sure the media sheet does not retack onto the fuser member. The air knife can be shut off after the decurler asserts tension on the media sheet.
At 260, the rotational speed of the decurler can be decelerated after asserting tension on the media sheet. The rotational speed of the decurler can be decelerated after asserting tension on the media sheet to reduce trail edge curl of the media sheet. For example, if the rotational speed of the decurler provides too much tension on the media sheet while the media sheet is still in the fuser member, the extra tension can cause the trail edge of the media sheet to curl. The decurler can be decelerated after reducing slag on the media sheet, to reduce wear on the decurler roll, and/or to avoid smears or scratches on an image on the media sheet. The rotational speed of the decurler can be reduced to a point that is slightly faster than the fuser member to keep tension on and to reduce slag of the media sheet. The rotational speed of the decurler can be accelerated after the media sheet exits the fuser member. For example, the rotational speed of the decurler can be accelerated after a trail edge of the media sheet exits the fuser member to transfer the media sheet to the next station or to match the speed of an inverter. The decurler can maintain this speed until the media sheet leaves the decurler. The decurler can also maintain this speed or reduce the speed until the lead edge of the next media sheet reaches the decurler. The decurler may operate at one accelerated speed and one decelerated speed for all operations or may operate at different accelerated and/or decelerated speeds depending on desired operation. The actual relative speeds of the fuser member, the decurler, an inverter, and other elements can be based on ratios based on geometry and operational relationships between elements according to desired operation.
Gas can applied from the air knife to the media sheet and tension can be asserted by the decurler on the media sheet while the media sheet is still in the fuser member to maintain constant image quality of the media sheet. For example, the timing of different speeds of the decurler and the timing of application of gas by the air knife can be set to avoid image quality defects on the media sheet. Thus, an image on the media sheet can look better and more consistent because the media sheet is detached at a consistent location on the fuser member relative to the fuser member nip point. At 270, the method ends.
The image production device 500 can include a marking engine 512, which can include hardware by which image signals are used to create a desired image. The image production device 500 can include a feeder module 514, which can store and dispense sheets on which images are to be printed. The image production device 500 can include a finisher 516, which may include hardware for stacking, folding, stapling, binding, and/or otherwise finishing prints which are output from the marking engine 512. If the image production device 500 is also operable as a copier or multifunction device, the image production device 500 can include a document feeder 518, which can operate to convert signals from light reflected from original hard-copy image into digital signals, which can be processed to create copies with the marking engine 512. The image production device 500 may also include a local user interface 520 for controlling its operations, although another source of image data and instructions may include any number of computers connected to the image production device 500 via a network.
The feeder module 514 can include any number of trays 530, each of which can store media sheets of a selected stock or type, such as size, weight, color, coating, and/or transparency. Sheets drawn from a selected tray 530 are moved to the marking engine 512 to receive one or more images thereon.
The marking engine 512 can be any marking engine, such as monochrome xerographic, color xerographic, ionographic, inkjet, or other marking engine. The marking engine 512 can include a photoreceptor 540, here in the form of a rotatable belt. The photoreceptor 540 is an example of what can be called a rotatable image receptor, meaning any rotatable structure such as a drum or belt which can temporarily retain one or more images for printing. Such an image receptor can comprise, by way of example and not limitation, a photoreceptor, or an intermediate member for retaining one or more ink, toner, or other marking material layers for subsequent transfer to a media sheet. The photoreceptor 540 can be entrained on a number of rollers, and a number of stations can be placed suitably around the photoreceptor 540. Such stations can include a charging station 542, an imaging station 544, a development station 546, and a transfer station 548. In an example embodiment, the imaging station 544 can be a laser-based raster output scanner in which a narrow laser beam scans successive scan lines oriented perpendicular to the process direction of the rotating photoreceptor 540. The laser can be turned on and off to selectively discharge small areas on the moving photoreceptor 540 according to image data to yield an electrostatic latent image, which can be developed with toner or other marking material at the development station 546 and transferred to a sheet at transfer station 548.
A sheet having received an image in this way can be subsequently moved through a fuser 550, such as the fuser member 110, and the heat and/or pressure from the fuser 550 can cause the toner image to become substantially permanent on the media sheet. For duplex or two-sided printing, the printed sheet can then be inverted and re-fed through the transfer station 548 to receive a second-side image. The finally-printed sheet can then be moved to finisher module 516, where it may be collated, stapled, folded, and/or otherwise finished with other media sheets.
Although the above description is directed toward a fuser member, such as a fuser used in xerographic printing, it will be understood that the teachings and claims herein can be applied to any treatment of marking material on a medium. For example, the marking material may comprise liquid or gel ink, and/or heat- or radiation-curable ink; and/or the medium itself may have certain requirements, such as temperature, for successful printing. The heat, pressure and other conditions required for treatment of the ink on the medium in a given embodiment may be different from those suitable for xerographic fusing.
Embodiments can provide for smoother image appearance and better image resolution. Embodiments can also reduce or eliminate distortion, such as mottle finish, on an image on media. For example, a more mottle appearance can occur the longer an image on media stays on a fuser during stripping. According to some embodiments, the document is stripped right at the fuser nip, which results in less time of the document on the fuser, which results in better image quality. Some embodiments eliminate a need for special hardware otherwise required to improve image quality. Some embodiments also eliminate a need for continuous use of an air knife. This can eliminate the need for a large compressor and can help to avoid overheating an air knife solenoid, which can improve duty cycles. Embodiments can also provide for an additional velocity of a decurler, which can reduce potential curl effect on a document. The additional velocity of the decurler can also reduce potential wear on the decurler.
For example, embodiments address the image quality defect problem by first running a decurler exit nip at a higher velocity than normal to remove document buckle and then slowing down to a normal exit speed in conjunction with turning off the air knife. This can keep a document strip point constant over the length of the media sheet and can eliminate the image quality defect. A velocity profile can be used on the exit nip along with air knife control to keep the strip point constant. This can provide for a lower cost compressor and can avoid streaks caused by fuser roll cooling from the air knife.
Some embodiments can be implemented on a programmed processor. However, the embodiments may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit such as a discrete element circuit, a programmable logic device, or the like. In general, any device on which resides a finite state machine capable of implementing the embodiments may be used to implement the processor functions of this disclosure.
While this disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for operation of the embodiments. For example, one of ordinary skill in the art of the embodiments would be enabled to make and use the teachings of the disclosure by simply employing the elements of the independent claims. Accordingly, the preferred embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure.
In this document, relational terms such as “first,” “second,” and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, relational terms, such as “top,” “bottom,” “front,” “back,” “horizontal,” “vertical,” and the like may be used solely to distinguish a spatial orientation of elements relative to each other and without necessarily implying a spatial orientation relative to any other physical coordinate system. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a,” “an,” or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term “another” is defined as at least a second or more. The terms “including,” “having,” and the like, as used herein, are defined as “comprising.”
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