Patent Application
20090067907
The present application relates generally to the field of image forming apparatus, and in particular, to sensors to detect the width of a media sheet as it moves along a media path within the image forming apparatus.
Image forming apparatus move a media sheet through an extended media path. The media sheet undergoes numerous image forming operations along the path such as initial input into the media path from an input tray or exterior input, image transfer area, and adhering the image to the media sheet. Problems can occur during these operations, especially if the device cannot anticipate and make adjustments to accommodate for different widths of media sheets.
In image forming apparatus with a fusing area, narrow media sheets moving through the fusing area may cause uneven heating of the fusing members. The uneven heating occurs between a first section of the fusing members that are contacted by the media sheets, and a second section that is not contacted by the media sheets. The first section maintains a first temperature range, while the second section maintains a second, higher temperature range. This uneven heating of the fusing members may result in inadequate fusing of the toner to the media sheets. The unequal heating may also decrease the life and reliability of the fusing members.
Another area affected by the width of the media sheets is the image transfer area. This area should be configured to prevent transfer of the image at a point off of the media sheet. Further, media sheets of differing widths may be moved along the media path in a different manner. This is especially evident when the media sheets are aligned to a particular reference location along the media path. Mishandling of the media sheets may result in media jams that can cause frustration, time, and money. Thus, there is a need for an effective manner to detect the width of a media sheet.
The present application is directed to sensors and methods of use to determine a width of a media sheet moving along a media path. In one embodiment, the sensor includes a shaft that extends at least partially across the media path. First and second paddles may extend outward from the shaft and into the media path. The paddles may be axially spaced apart along a length of the shaft, and the first paddle may be positioned upstream along the media path from the second paddle. A flag may extend outward from the shaft. A detector may be positioned in proximity to the shaft. In use, the shaft may rotate during contact between the media sheets and the paddles to move the flag. The detector may be able to differentiate between a first amount of rotation due to contact with a wide media sheet and a second amount of rotation with a narrow media sheet to determine a width of the media sheets.
The present application is directed to a media width sensor 10 for use in an image forming apparatus 100.
The apparatus 100 of
An intermediate transfer mechanism (ITM) 130 is disposed adjacent to each of the imaging units 121. In this embodiment, the ITM 130 is formed as an endless belt trained about support roller 131, tension roller 132 and back-up roller 133. During image forming operations, the ITM 130 moves past the imaging units 121 in a clockwise direction as viewed in
The ITM 130 rotates and collects the one or more toner images from the imaging units 121 and then conveys the toner images to a media sheet at a second transfer area. The second transfer area includes a second transfer nip 140 formed between the back-up roller 133 and a second transfer roller 141.
A media path 90 extends through the apparatus 100 for moving the media sheets through the imaging process. The media sheets are initially stored in an input tray 119 or introduced through a manual feed 148. The sheets in the input tray 119 are contacted by a pick mechanism and moved into the media path 90. For sheets entering through the manual feed 148, one or more rollers are positioned to move the sheet into the second transfer nip 140.
The media sheets receive the toner image from the ITM 130 as it moves through the second transfer nip 140. The media sheets with toner images are then moved along the media path 90 and into a fuser area 150. Fuser area 150 includes fusing members 151 such as rollers or belts that form a nip to adhere the toner image to the media sheet. The fused media sheets then pass through exit rollers 145 that are located downstream from the fuser area 150. Exit rollers 145 may be rotated in either forward or reverse directions. In a forward direction, the exit rollers 145 move the media sheet from the media path 90 to an output area 147. In a reverse direction, the exit rollers 145 move the media sheet into a duplex path 146 for image formation on a second side of the media sheet.
The sensor 10 may be positioned at various locations along the media path 90 to detect a width of the media sheets.
The terms “upstream” and “downstream” describe the position of elements relative to the direction of media sheet movement along the media path 90. A media sheet moving along the media path 90 will pass an upstream element prior to passing a downstream element. By way of example and using the embodiment of
Media sheets are aligned along a reference location 91 as they move along the media path 90 in the direction of arrow B. The media sheet strike one of the paddles 21, 22 depending upon the media sheet width. A wide sheet will contact paddle 21, and a narrow sheet will contact paddle 22. Contact with the media sheet causes the arm 20 to rotate and the flag 50 to move through the detector 30. Contact of the different paddles 21, 22 causes different degrees of rotation of the arm 20 that differentiated by the detector 30.
The paddles 21, 22 are axially spaced apart along the shaft 24 and positioned across the media path 90. The paddles 21, 22 are positioned a distance away from the reference location 91 that aligns the media sheets while they move along the media path 90. As illustrated in
Flag 25 extends outward from the shaft 24 at a different angular position than the paddles 21, 22. Flag 25 is positioned to move through the detector 30 during rotation of the arm 20. A pair of windows 50, 51 extends through the flag 25 and are positioned to move through the detector 30 during rotation of the arm 20. In the embodiment of
Detector 30 includes a transmitter 31 and a receiver 32. The transmitter 31 emits a signal that is detectable by receiver 32. In one embodiment, the signal is electromagnetic energy. In one embodiment, sensor 30 is an optical sensor. Thus, transmitter 31 emits optical energy with a frequency spectrum that is detectable by receiver 32. The transmitter 31 may be embodied as an LED, laser, bulb or other source. Receiver 32 changes operating characteristics based on the presence and quantity of optical energy received. The receiver 32 may be a phototransistor, photodarlington, or other detector. The optical energy may consist of visible light or near-visible energy (e.g., infrared or ultraviolet). Further, flag 25 is positioned within the transmission path between the transmitter 31 and receiver 32. Where an optical sensor 30 is used, the flag 25 is positioned within the optical path between the transmitter 31 and receiver 32 and operates as an interrupter of sorts.
Controller 70 determines the width of the media sheets based on signals received from the detector 30. In one embodiment, controller 70 includes a microcontroller with associated memory. Controller 70 may oversee movement of the media sheet along the entire media path 90, or may just determine the width of the media sheet as it moves through the sensor 10.
In one method of use with the embodiment illustrated in
A second, narrower media sheet moving along the media path 90 contacts paddle 22. Because of the narrow width, the media sheet will not contact paddle 21. Contact with paddle 22 causes the arm 20 to rotate a second amount causing only window 51 to move within the transmission path between the transmitter 31 and receiver 32. Contact with the second paddle 22 causes the arm 20 to rotate a lesser degree because of the downstream position of the paddle 22 along the shaft 20. This movement of the flag 25 within the detector 30 causes a second disturbance pattern that is signaled to the controller 70 which associates the signal with a media sheet of a second, narrower width.
In this embodiment, upstream paddle 21 is positioned a greater distance from the reference location 91 than downstream paddle 22. This ensures each media sheet will only contact a single paddle. A wide media sheet will only contact the upstream paddle 21, and will be spaced away from the downstream paddle 22. Likewise, a narrow media sheet will only contact the downstream paddle 22 and not the upstream paddle 21. In another embodiment, the media sheet contacts each of the paddles 21, 22 with the sheet initially contacting one of the paddles and then subsequently contacting the other paddle as the media sheet moves further along the media path 90.
In the described method, signals are caused by either one or both windows 50, 51 moving through the detector 30. In other embodiments, disturbance patterns may be caused by more than two windows moving within the transmission path. Also, windows 50, 51 may include different shapes and sizes that cause different detectable patterns. In another embodiment, a first width media sheet moves the arm 20 such that no windows pass through the detector 30, while a second width media sheet causes at least one window to move within the detector 30.
In the embodiment of
The embodiment of
In the embodiment of
The embodiment illustrated in
Co-pending U.S. patent application Ser. No. ______ (Attorney Reference No. 2006-0475.03) discloses a method of determining a width of a media sheet moving along a media path and is herein incorporated by reference.
Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc and are also not intended to be limiting. Like terms refer to like elements throughout the description.
As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. In one embodiment, the flag 25 is positioned away from the media path 90. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
