Envelope transport structure

Abstract: A media transport unit (18) includes an envelope transport structure that utilizes support fingers (17) directly under the envelope (28). The support fingers are canted toward the center line of the paper path. The envelope flap (29) passes over the support fingers at an angle that prevents the envelope flap from catching a support finger and potentially causing envelope wrinkling or a jam. The support fingers on either side of the area over which the envelope passes are canted away from the center line of the paper path to prevent the edges of full width media from catching the surface of a support finger.

Description: This invention relates generally to imaging of envelopes and, more specifically, to an envelope transport structure that minimizes wrinkling of envelopes during an imaging process. In electrostatic or electrophotographic image forming apparatus, such as monochrome and color laser printers and photocopiers, it is common to fuse a loose toner image by passing the imaged media through a fusing nip. The fusing nip is typically formed from a first fusing roller urged against a second fusing roller to create a pressurized nip through which the media passes. One or both of the fusing rollers are typically heated to increase the temperature within the nip. In those imaging systems utilizing a fusing nip as described above, wrinkling of envelopes within the fusing nip has been a continuing problem. Previous attempts to reduce envelope wrinkling have involved relieving the pressure on the envelopes at various points in the fusing operation. An example of this approach is found in U.S. Patent No. 5,268,726 to Oleksa et al. It is also known to utilize individual support ribs or fingers within a paper path to reduce friction between the moving media and the surfaces of the paper path. The support fingers also serve to lessen pre-heating of the media due to heat transfer from the support surfaces of the paper path. Additionally, to prevent any one point on the image from being in extended continuous contact with a single support finger, the fingers may be angled with respect to the direction of travel of the media. This helps to avoid uneven heating of the media and image that can cause print defects and variations in the gloss of the printed image. It is also known to angle the support fingers away from the center line of the paper path to prevent the leading corners of a media sheet from catching the sides of the fingers and pushing the media laterally to either side of the paper path. Should the media be pushed laterally prior to the fusing nip, wrinkling can occur and, in a worst case scenario, a paper jam may be created. An example of utilising support fingers that are canted away from the center line of the paper path is found in co-pending application number EP 99300929.9 entitled APPARATUS AND METHOD FOR CONTROLLING MEDIA TEMPERATURE IN AN IMAGING APPARATUS and assigned to the assignee of the present application (EP-A-0955570). It has been found that support fingers that are canted away from the center line of the paper path have a disadvantage when printing envelopes. When the addressee side of an envelope is printed and the envelope travels along the paper path, the flap of the envelope on the opposite side hangs down at an angle that is canted away from the center line of the paper path, similar to the angle of the canted support fingers. As the envelope travels over the support fingers, the flap may catch the side of a finger and cause the envelope to be pushed laterally to the side or opened while moving through the fuser. This can cause severe wrinkling, print defects, and/or a media jam. JP-A-04223936 describes an envelope feeder of the prior art forming the preamble of claims 1, 8 and 16. It is the object of the present invention to improve an envelope transport structure with regard to providing higher reliability. This object is achieved by providing an envelope support structure according to claim 1, an imaging apparatus according to claim 8, and a media transport unit according to claim 16. Embodiments of the invention are set forth in the dependent claims. It is an advantage of the present invention that the envelope transport structure comprises a simple and compact design that utilizes low-cost components. Still other aspects, features, and advantages of the present invention will become apparent to those skilled in this art from the following description, wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modifications in various, obvious aspects, all without departing from the invention as claimed. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. And now for a brief description of the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of an electrophotographic printing apparatus showing the media path through the printer. Fig. 2 is a schematic perspective view of a pair of fusing rollers forming a fusing nip and an envelope traveling along the media path and approaching an envelope transport structure upstream from the fusing nip. Fig. 3 is a schematic top view of the envelope transport structure showing the positioning and orientation of the individual media supports and an envelope approaching the supports. Fig. 4 is an enlarged schematic top view of the envelope traveling over the media supports. Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Fig. 1 is a schematic illustration of the media path 12 in an electrostatic or electrophotographic image forming apparatus 10 that utilizes the envelope transport structure of the present invention. The following description of a preferred embodiment of the invention refers to its use in an electrostatic printing apparatus. It will be appreciated, however, that the apparatus of the present invention may be used with other types of electrostatic imaging apparatus, such as photocopiers, and with other types of imaging apparatus, such as aqueous ink jet printers. Accordingly, the following description will be regarded as merely illustrative of one embodiment of the present invention. With continued reference to Fig. 1 a receiving substrate 11, such as a sheet of paper or an envelope, is picked from a media tray 14 by a conventional pick roller mechanism (not shown). The receiving substrate 11 travels along the media path 12 and through an imaging station 16 which deposits a toner image on the receiving substrate. An example of an electrostatic imaging station is found in U.S. Patent 5,576,824 (the '824 patent) entitled FIVE CYCLE IMAGE ON IMAGE PRINTING ARCHITECTURE. After passing through the imaging station 16, the receiving substrate 11 travels over a media transport unit 18 that includes an envelope transport structure, described in more detail below. The media transport unit 18 is positioned in a pre-nip portion of the media path 12 upstream from the fusing nip 20. The fusing nip 20 is created by urging together fusing rollers 22 and 24. In the fusing nip 20, the toner image is permanently affixed to the receiving substrate 11. After passing through the fusing nip 20, the receiving substrate is transported out of the printer 10 for retrieval by a user. With reference now to Fig. 3, the arrangement and operation of the media transport unit 18 and envelope transport structure 19 of the present invention will now be described in more detail. The media transport unit 18 includes a plurality of media supports for supporting a sheet of media or an envelope as the sheet or envelope approaches the fusing nip 20. In the preferred embodiment, the media supports comprise elongated, spaced apart support fingers indicated by the even numbered reference numerals 30-52, with each finger including a first end and a second end indicated by a prime and double prime, respectively, of the corresponding reference numeral. For example, finger 30 includes a first end 30' and a second end 30". The support fingers are arranged in a first lateral portion 60 comprising support fingers 30, 32, 34, and 36, and a second lateral portion 62 comprising support fingers 46, 48, 50, and 52. Between the first lateral portion 60 and the second lateral portion 62 is a center portion 64 comprising support fingers 38, 40, 42, and 44. As explained below, the center portion 64 of support fingers corresponds to the envelope transport structure 19. It will be appreciated that any suitable number of support fingers may be utilized in any of the first lateral, second lateral and center portions. With continued reference to Fig. 3, the media path 12 includes a center line indicated by the dotted line 15. Sheets of media and envelopes travel in the direction of action arrow A along the media path 12 and are generally centered over the center line 15. As shown in Fig. 3, the support fingers in the first and second lateral portions 60, 62 are canted away from the media path center line 15. Preferably, each of the support fingers in the first and second lateral portions 60, 62 form an angle with the center line 15 of between about 3 degrees and about 45 degrees, and more preferably between about 10 degrees and about 20 degrees. As explained above, this ensures that the edges of a media sheet (not shown) do not contact the side of a support finger, which can urge the media sheet laterally out of alignment as it travels through the fusing nip 20 and potentially cause media wrinkling and/or a media jam. In an important aspect of the present invention, the support fingers 38-44 in the center portion 64/envelope transport structure 19 are each canted toward the media path center line 15. Preferably, each of the support fingers 38-44 form an angle with the center line 15 of between about 3 degrees and about 45 degrees, and more preferably between about 10 degrees and about 20 degrees. With reference now to Fig. 4, as an envelope 28 travels over the envelope transport structure 19 with the envelope flap 29 on the underside of the envelope, the flap rides over the top of the support fingers 38 and 40. The flap 29 and support finger 38 initially create an acute angle 41 that allows the flap to ride over the top of the support finger. With reference now to Fig. 3, the long edges 31, 32 of the envelope 28 travel between the first lateral portion 60 and the center portion 64 of support fingers, and between the second lateral portion 62 and center portion 64 of support fingers, respectively. In the preferred embodiment, the distance between the first end 38' of support finger 38 and the first end 44' of support finger 44 is less than the length of the short edge 35 of the envelope 28. Additionally, the distance between the first end 36' of support finger 36 and the first end 46' of support finger 46 is greater than the length of the short edge 35 of the envelope 28. It will be appreciated that standard letter envelopes have a long edge length of between about 9.5 inches (241 mm.) and 9.8 inches (250 mm.), and a short edge length of about 4.0 inches (102 mm). In the preferred embodiment, the support fingers 38 and 40 on a first side of the center line 15 are substantially parallel. Similarly, the support fingers 42 and 44 on the opposite side of the center line 15 are substantially parallel. While the invention has been described above with references to specific embodiments thereof, it is apparent that many changes, modifications and variations in the materials, arrangements of parts and steps can be made without departing from the scope of the claims. Accordingly, the scope of the appended claims is intended to embrace the use of these other inks and all other changes, modifications and variations that may occur to one of skill in the art upon a reading of the disclosure.

Claims: An envelope transport structure (19) for supporting an envelope (28) having a flap (29) as the envelope travels in a travel direction along a media path (12) in an imaging apparatus, the media path including a center line (15), the envelope transport structure comprising: a plurality of media supports (38, 40, 42, 44) for supporting the envelope as the envelope travels along the media path, the plurality of media supports being canted in travel direction toward the center line (15) of the media path, whereby the envelope flap (29) travels over and is in contact with at least one of the media supports, characterized in that an envelope travel path is substantially centered over said center line (15). The envelope transport structure of claim 1, wherein the plurality of media supports comprise a plurality of elongated, spaced apart fingers. The envelope transport structure of claim 2, wherein the envelope transport structure is suitable to transport the envelope (28) including a short edge (35) and a long edge (31), each of the elongated fingers includes a first end (38', 40', 42', 44') disposed upstream relative to the travel direction and a second end (38", 40", 42", 44") disposed downstream relative to the travel direction, the plurality of fingers includes a first outermost finger (38) and a second outermost finger (44), and a distance between the first end (38') of the first outermost finger (38) and the first end (44') of the second outermost finger (44) is less than a length of the short edge (35) of the envelope. The envelope transport structure of claim 3, wherein the elongated fingers on a first side of the center line (15) are substantially parallel. The envelope transport structure of claim 3 or 4, wherein the elongated fingers on a second side of the center line (15) are substantially parallel. The envelope transport structure of any of claims 2 to 5, wherein the elongated fingers are canted toward the center line (15) of the media path at an angle of between about 3 degrees and about 45 degrees with respect to the center line. The envelope transport structure of any of claims 3 to 6, wherein the envelope transport structure is suitable to transport envelopes having a length of the short edge of about 102 mm (four inches). An imaging apparatus (10) capable of imaging on an envelope (28) having a flap (29), the imaging apparatus comprising: an imaging station (16) for applying imaging material to the envelope to create an image; a fusing station for fusing the imaging material into the envelope; a media path (12) having a center line (15) and extending between the imaging station (16) and the fusing station; and an envelope transport structure (19) for supporting the envelope (28) as the envelope travels in a travel direction along the media path (12), the envelope transport structure being disposed upstream from the fusing station, and comprising: a plurality of media supports (38, 40, 42, 44) for supporting the envelope (28) as the envelope travels along the media path (12), the plurality of media supports being canted in travel direction toward the center line (15) of the media path, whereby the envelope flap (29) travels over and is in contact with a least one of the media supports, characterized in that an envelope travel path is substantially centered over said center line (15). The imaging apparatus of claim 8, wherein the plurality of media supports comprise a plurality of elongated, spaced apart fingers. The imaging apparatus of claim 9, wherein the envelope transport structure is suitable to transport envelopes having a short edge (35) and a long edge (31), each of the elongated fingers includes a first end (38', 40', 42', 44') disposed upstream relative to the travel direction and a second end (38", 40", 42", 44") disposed downstream relative to the travel direction, the plurality of fingers is bounded by a first outermost finger (38) and a second outermost finger (44), and a distance between the first end (38') of the first outermost finger (38) and the first end (44') of the second outermost finger (44) is less than a length of the short edge (35) of the envelope. The imaging apparatus of claims 9 or 10, wherein the elongated fingers on a first side of the center line (15) are substantially parallel. The imaging apparatus of claim 11, wherein the elongated fingers on a second side of the center line (15) are substantially parallel. The imaging apparatus of any of claims 9 to 12, wherein the elongated fingers are canted toward the center line (15) of the media path at an angle of between about 3 degrees and about 45 degrees with respect to the center line. The imaging apparatus of any of claims 10 to 13, wherein the elongated fingers are positioned in a pre-nip portion of the media path (12) that is upstream from a fusing nip (20) in the imaging apparatus, and wherein the second end of each of the elongated fingers is closer to the fusing nip than the first end of each of the elongated fingers. The imaging apparatus of any of claims 10 to 14, wherein the envelope transport structure is suitable to transport envelopes having a length of the short edge of about 102 mm (four inches). A media transport unit for supporting a receiving substrate as the receiving substrate travels in a travel direction along a media path (12) in an imaging apparatus (10), the media path including a center line (15), the receiving substrate being a copy sheet substrate or an envelope, the media transport unit comprising: a plurality of media supports (30, 36, 38, 44, 46, 52) for supporting the receiving substrate as the receiving substrate travels along the media path (12), the plurality of media supports including a first lateral portion (60), a second lateral portion (62) and a center portion (64) between the first lateral portion and the second lateral portion; the media supports (30, 36, 46, 52) in the first lateral portion (60) and in the second lateral portion (62) being canted in travel direction away from the center line (15) of the media path; and the media supports (38, 44) in the center portion (64) for supporting the envelope as the envelope travels along the media path over the center portion (64), whereby the envelope flap (29) travels over and is in contact with at least one of the media supports of the center portion (64), characterized in that the media supports in the center portion (64) being canted in travel direction toward the center line (15) of the media path, and an envelope travel path is substantially centered over the center line (15). The media transport unit of claim 16, wherein the plurality of media supports comprise a plurality of elongated, spaced apart fingers. The media transport unit of claim 17, wherein the media transport unit is suitable to transport envelopes having a short edge (35) and a long edge (31), each of the elongated fingers includes a first end (38', 40', 42', 44') disposed upstream relative to the travel direction and a second end (38", 40", 42", 44") disposed downstream relative to the travel direction, the center portion (64) of fingers includes a first outermost finger (38) and a second outermost finger (44), and a distance between the first end (38') of the first outermost finger (38) and the first end (44') of the second outermost finger (44) in the center portion (64) is less than a length of the short edge of the envelope.

Inventors: TIDRICK ROBERT C, TIDRICK, ROBERT C.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1999
Main classification: G03G15
IPC codes: B65H5, G03G15