US3849905A - Fusing apparatus - Google Patents

Fusing apparatus Download PDF

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Publication number
US3849905A
US3849905A US00421710A US42171073A US3849905A US 3849905 A US3849905 A US 3849905A US 00421710 A US00421710 A US 00421710A US 42171073 A US42171073 A US 42171073A US 3849905 A US3849905 A US 3849905A
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US
United States
Prior art keywords
sheet
fuser
fusing
curl
transport means
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00421710A
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English (en)
Inventor
D Bierworth
F Hynes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xerox Corp
Original Assignee
Xerox Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
Priority to US00421710A priority Critical patent/US3849905A/en
Priority to CA211,160A priority patent/CA1045671A/fr
Application granted granted Critical
Publication of US3849905A publication Critical patent/US3849905A/en
Priority to JP49136611A priority patent/JPS5757704B2/ja
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2007—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using radiant heat, e.g. infrared lamps, microwave heaters

Definitions

  • a fusing apparatus for heat fusing a toner image to a sheet of final support material.
  • the apparatus includes a source of heat radiation for application to the sheet.
  • a fusing zone is defined wherein the heat source is effective to fuse the image to the sheet and a flow of air is present at the zone.
  • Means are provided cooperating with the fuser for reducing curl of the sheet during fusing.
  • the curl reducing means comprise at least one seal adjacent the fusing zone for limiting air flow at the zone to an amount at which curl of the sheet is substantially reduced.
  • This invention relates to a fusing apparatus for heat fusing a toner image to a sheet of final support material including means for reducing curl of the sheet during fusing.
  • each apparatus the transfer of heat energy to the record card by conduction and convection is kept negligible by a suitable means, and thereby, since the record card per se is made from paper stock and does not readily absorb radiant energy, the temperature of the record card is kept at a lower value than the boiling point of water.
  • Transfer of heat energy by conduction and convection is reduced either by heat extraction or so called fixing station cooling, or by the use of a heat transfer barrier for preventing heat transfer by conduction and convection such as a water filled glass jacket, or in accordance with the third embodiment, by focusing and concentrating the radiant energy on the toner image.
  • a fusing apparatus has been developed wherein curl of the sheet during fusing is substantially reduced or eliminated.
  • the fuser includes a source of heat radiation.
  • a fusing zone is defined wherein the heat source is effective to fuse a toner image to a sheet of final support material.
  • a flow of air is present at the zone due to influences which are internal and/or external of the fuser.
  • the curl reducing means comprises at least one seal adjacent to the fusing zone which limits the air flow at the zone to an amount at which curl of the sheet is reduced or eliminated.
  • the air flow has to be limited severely in order to reduce moisture gradients and to prevent the moisture driven off from the sheet from being completely withdrawn from the fusing zone.
  • transport means are provided at the exit and/or entrance regions of the fuser to transport the sheet.
  • One or more of these transports may include suction means for holding the sheet to the transport.
  • the seals preferably extend between the transports and the fuser.
  • the curl reducing means includes means for reducing the air flow through the fusing zone.
  • FIG. 1 shows schematically an exemplary reproducing machine including the fusing apparatus of this invention.
  • FIG. 2 is a perspective view of a sheet of final support material after fusing by a prior art radiant fuser.
  • FIG. 3 is a cross-sectional side view of the fusing apparatus of this invention including the curl reducing means.
  • a fusing apparatus 1 for heat fusing a toner image to a sheet 2 of final support material.
  • the fusing apparatus 1 includes a fuser 3 having a source of heat radiation 4 for application to the sheet.
  • the fuser 3 defines a fusing zone 5 wherein the heat source 4 is effective to fuse the image to the :sheet 2.
  • a flow of air is present at the zone 5 due to influences which may be internal and/or external of the fuser 3.
  • An essential part of this invention comprises means which cooperate with the fuser 3 for reducing curl of the sheet 2 during fusing.
  • the curl reducing means 6 preferably comprise at least one seal adjacent to the fusing zone 5 which is adapted to limit air flow through the zone to a volume at which curl of the sheet is substantially reduced.
  • paper curl in the final support sheet after fusing by means of a radiant fuser is the result of plastic deformation of the paper sheet.
  • the deformation is made up of two components which may be summed algebraically.
  • One component is related to the type of paper and to the bulk paper changesthat occur during fusing. It is possible to think of these as resulting from one or both of the following: I. a locked in asymmetric residual stress distribution which relaxes or yields under a bulk temperature or moisture level excursion. 2. variations in paper properties across the thickness of the sheet, as for example, the coefficient or expansion with mois' ture. This can result in non-uniform elongation of the sheet and curl in the absence of any assymetry or gradients.
  • the other component is believed to relate to the asymmetrical conditions or gradients imposed on the paper by the fuser and adjacent machine components or other external influences. The curl from this component is always in the direction of the source of radiant energy.
  • the primary source of the stresses is the moisture gradient which causes the top surface of the sheet to shrink more than the bottom surface.
  • the moisture gradient is determined by the temperature gradient, the initial moisture content and the moisture mass transfer effects. In many cases the moisture mass transfer is significant.
  • the air moving device may aggrevate curl by increasing the rate of moisture mass transfer due to increased air flow in the fusing zone.
  • the rate of moisture mass transfer is substantially increased in the top surface of the sheet thus causing a larger moisture gradient which results in higher stresses and greater deformation of the sheet.
  • Other aspects of the mechanism causing curl in the sheets are described in US. Pat. No. 2,807,703.
  • FIG. 2 a sheet 2 of final support material is shown after fusing by an apparatus not including the curl preventing means 6 in accordance with this invention.
  • the sheet 2 shown therein has a substantial curl 7 of about 1.5 inches at the trailing edge portion 8 thereof.
  • This type of curl 7 in a sheet 2 is formed by an apparatus 10 as will be described in more detail with reference to FIG. 1 when the curl preventing means 6 are not employed. In other apparatuses the curl 7 may be more or less pronounced.
  • FIG. 1 there is shown by way of example an automatic xerographic reproducing machine 10 which incorporates the improved fusing apparatus 1 of the present invention.
  • the reproducing machine 10 depicted in FIG. 1 illustrates the various components utilized therein for producing copies from an original.
  • the fusing apparatus 1 of the present invention is particularly well adapted for use in an automatic xerographic reproducing machine 10, it should become evident from the following description that it is equally well suited for use in a wide variety of machines where an image is fused to a sheet of final support material and it is not necessarily limited in its application to the particular embodiment shown herein.
  • the reproducing machine 10 illustrated in FIG. I employs an image recording drum-like member 11 the outer periphery of which is coated with a suitable photoconductive material 12.
  • a suitable photoconductive material is disclosed in US. Pat. No. 2,970,906 issued to Bixby in 1961.
  • the drum 1] is suitably journaled for rotation within a machine frame (not shown) by means of a shaft 13 and rotates in the direction indicated by arrow 13, to bring the image retaining surface thereon past a plurality of xerographic processing stations.
  • Suitable drive means (not shown) are provided to power and coordinate the motion of the various cooperating machine components whereby a faithful reproduction of the original input scene information is recorded upon a sheet 2 of final support material.
  • FIG. 1 The various processing stations for producing a copy of an original are herein represented in FIG. 1 as blocks A to E.
  • the drum 11 moves photoconductive surface 12 through charging station A.
  • charging station A an electrostatic charge is placed uniformly over the photoconductive surface 12 of the drum 11 preparatory to imaging.
  • the charging may be provided by a corona generating device of a type described in US. Pat. No. 2,836,725 issued to Vyverberg in 1958.
  • the drum 11 is rotated to exposure sta tion B where the charged photoconductive surface 12 is exposed to a light image of the original input scene information, whereby the charge is selectively dissipated in the light exposed regions to record the original input scene in the form of a latent electrostatic image.
  • a suitable exposure system may be of the type described in US. Pat. application, Ser. No. 259,181 filed June 2, 1972.
  • drum 11 rotates the electrostatic latent image recorded on the photoconductive surface 12 to development station C wherein a conventional developer mix is applied to the photoconductive surface 12 rendering the latent image visible.
  • a suitable development station is disclosed in US. Pat. application, Ser. No. 199,481 filed Nov. 17, 1971.
  • the application describes a magnetic brush development system utilizing a magnetizable developer mix having carrier granules and a toner colorant.
  • the developer mix is continuously brought through a directional flux field to form a brush thereof.
  • the electrostatic latent image recorded on photoconductive surface 12 is developed by bringing the brush of developer mix into contact therewith.
  • the developed image on the photoconductive surface 12 is then brought into contact with a sheet 2 of final support material within a transfer station D and the toner image is transferred from the photoconductive surface 12 to the contacting side of the final support sheet 2.
  • the final support material may be paper, plastic, etc., as desired.
  • the sheet with the image thereon is advanced to a suitable fuser 3, which coalesces the transferred powdered image thereto.
  • suitable fuser is described in 11.8. Pat. No. 2,701,765, issued to Codichini et al in 1955.
  • the sheet 2 is advanced by snuffing rolls 14 and then by rolls 15 to a catch tray 16 for subsequent removal therefrom by the machine operator.
  • the residual toner particles remaining on the photoconductive surface 12 after the transfer operation are removed therefrom as it moves through cleaning station E.
  • the residual toner particles are first brought under the influence of a cleaning corona generating device (not shown) adapted to neutralize the electrostatic charge remaining on the toner particles.
  • the neutralized toner parti cles are then mechanically cleaned from the photoconductive surface 12 by conventional means as, for example, the use of a resiliently biased knife blade as set forth in US. Pat. No. 3,660,863 issued to Gerbasi in 1972.
  • the sheets 2 of final support material processed in the automatic xerographic reproducing machine can be stored in the machine within a removable paper cassette 17.
  • a suitable paper cassette is set forth in US. Pat. application, Ser. No. 208,183 filed Dec. 15,1971, now US. Pat. No. 3,767,187.
  • the reproducing apparatus in accordance with this invention can also have the capability of accepting and processing copy sheets 2 of varying lengths.
  • the length of the copy sheet 2 of course, being dictated by the size of the original input scene or information recorded on the photo-conductive surface 12.
  • the paper cassette 17 is preferably provided with an adjustable feature whereby sheets of varying length and width can be conveniently accommodated.
  • the eassette 17 is filled with a stack of final support material 2 of pre-selected size and the cassette is inserted into the machine by sliding along a base plate (not shown) which guides the cassette into operable relationship with a pair of feed rollers 18.
  • the top sheet of the stack is separated and forwarded from the stack into the transfer station D by means of registration rolls 19.
  • FIG. 3 that portion of the reproducing machine 10 of P16. 1 embodying the fusing apparatus 1 of this invention is shown in greater detail.
  • the view shown is aside view and it should be readily evident that the fusing apparatus extends across the entire sheet in a direction normal to the plane of the Figure.
  • the image bearing sheet 2 after passing through the transfer station D of FIG. 1 upon separation from the photoconductive surface 12, is allowed to fall into Contact with a vacuum belt transport system 20 which conveys the sheet directly to the fusing apparatus 1.
  • the fusing apparatus 1 shown includes a radiant type fuser- 3.
  • the fuser 3 includes a heated platen 30 mounted to engage the non-image bearing side of the copy sheet 2 which moves in sliding contact therewith as it is transported through the fusing zone.
  • the heated platen 30 is designed so that an eflcient heat flow is established between the platen and the copy sheet 2 to raise the temperature of the sheet rapidly to a level somewhat below the sheets scorch temperature.
  • the radiant energy source for fusing is provided by an infrared quartz lamp 31 which is mounted in a reflector assembly 32 in opposing relationship to the heated platen 30 and in a position to thermally communicate with the newly imaged side of the copy sheet 2.
  • the spectral output of the lamp 31 is within a range at which the imaging material which may be toner for a xerographic machine 10 is highly absorptive and at which the support material 2 which may be paper is relatively non-absorptive.
  • a forced air cooling chamber 33 is provided about the backside of the reflector assembly 32 to cool the fuser 3 in opera tion.
  • a heating element 34 is provided in the platen 30 to maintain it at the desired temperature during standby periods.
  • the preheat element is disconnected and the platen 31) receives its heat input directly from the quartz lamp.
  • the snuffing rolls 40 and 41 forward the sheet along a guide plate 42 into the nip of a pair of advancing rolls 43 which deposit the sheet within a collecting tray 16.
  • the collecting tray 16 includes a base plate 44 inclined upwards and an upwardly turned margin stop 45.
  • the transport comprises a vacuum transport having a suction means 21 which draws air in through or between the belts 22.
  • the suction means is connected to any conventional source of suction (not shown).
  • the suction means 21 cooperates with the belts 22 to firmly hold a sheet 2 of final support material in contact with the transport.
  • the suction means 21 comprises, however, only one of many possible external influences in the machine 10 which can cause an air flow through the fusing zone 5.
  • the suction means 21 draws air in from an external port (not shown). Air flows through various passageways defined by the machine components and sub-stations.
  • the paper path provides one of the key flow channels for the air which flows to the suction means 21.
  • the internal means comprises a series of orifices 38 in the platen 30 which communicate with a suction means comprising the chamber 37.
  • the purpose of these orifices 38 is to provide a vacuum holddown for holding the sheet 2 in contact with the platen 30 as it passes through the fuser 3.
  • a substantial air flow is produced.
  • the direction of this air flow will vary depending on whether the sheet is entering or leaving the fuser.
  • Another internal cause of air flow comprises the conductive air currents associated with the fuser 3.
  • an air flow through the fusing zone is created both by external influences and by in ternal influences. It is believed. however, that either of these influences alone would be sufficient to provide an air flow through the fusing zone which would result in a substantially curled copy sheet.
  • curl preventing means 6 comprise in the embodiment shown one or more seals 61, 62, 63 and 64 adjacent to the fusing zone 5 which are adapted to limit the air flow at the zone to an amount at which curl of the sheet is substantially reduced or eliminated.
  • the provision of the seal 61 between the top portion 65 of the fuser 3 and the upper transport roll 40 at the exit side of the fuser provides a substantial reduction in curl as compared to the same apparatus without the seal 61.
  • the reduction in curl due to this seal 61 has been shown to be as much as about percent or more.
  • the fusing apparatus illustrated in FIG. 3 requires seals between the downstream sheet transport 40 and 41 and the fusing apparatus 3 in order to substantially reduce or eliminate curl 7. It should also be apparent that had the vacuum transport 20 or other external source of substantial air flow through the fuser 3 been downstream of the fuser rather than upstream thereof, then the effective seals for reducing air flow through the fuser would have been the upstream seals 63 and 64, rather than the downstream seals 61 and 62. In this case the seal 63 between the upper portion 65 of the fuser 3 and the adjacent housing E would have had to be impervious, whereas the seals 61 and 62 on the downstream side of the fuser could have been pervious as desired.
  • the internal suction means 37 and 38 does not exert a controlling influence on the amount of curl which is formed. Regulation of the suction force here, in cooperation with the seals 61 64 could help reduce air flow through the fusing zone 5. Conversely increasing the suction force would restrain deformation caused by the moisture gradient, however, it would also increase the retardation forces on the sheet 2 which could cause the sheet to stall in the fuser 3 which is undesirable.
  • seals 61 64 The location of the seals 61 64 has to be determined based on the air flow conditions in the apparatus in which the fuser 3 is employed and seals 61 64 may be employed at one or all of the locations shown in order to provide the reduced air flow through the fuser.
  • the most significant seals will be those adjacent the image containing side of the sheet 2, for an apparatus where the sheet is passed over a platen 30, since it is on this side of the sheet that the greatest air flow occurs.
  • the seals 61, 62 and 63 shown comprise elongated strip-type members formed of a resilient material which is biased against the transports 20 or 40 and 41, and extend over the gaps between the transports or other housings (E) and the fuser.
  • the seals 61 64 are at least coextensive with the fusing zone 5 in the transverse direction, (e.g., the direction normal to the plane of FIG. 3).
  • the seals may be secured to the fuser by any desired means as, for example, adhesively.
  • the resilient material comprises a polymeric material such as polytetrafloroethylene sold under the trademark Tetlon, or polyethyleneterephthalate sold under the trademark Mylar which have been found to be us able materials as seals in accordance with this invention.
  • Holes 67 or other perforations can be employed as in seal 63 to provide means for adjusting the degree to which the seal reduces the air flow through the fusing zone 5 as by providing an alternate air channel as shown.
  • the seals should be
  • the toner images of this invention may be formed ,from toner of the types described in U.S. Pat. Nos.
  • a fusing apparatus for heat fusing a toner image to a sheet of final support material including:
  • a fuser having a source of heat radiation for applica' tion to said sheet, said fuser defining a fusing zone wherein said heat source is effective to fuse said image to said sheet, and a flow of air at said Zone; the improvement wherein said apparatus further includes;
  • first transport means for transporting said sheet, said transport means being located adjacent said fuser, an air channel being defined between said transport means and said fuser;
  • said curl reducing means comprising at least one seal extending over a gap between said fuser and said transport means for limiting air flow at said zone to an amount at which curl of said sheet is substantially reduced.
  • first transport means is located at a first side of said fuser and wherein a second transport means is provided at the opposing side of said fuser and wherein at least one of said first and second transport means includes suction means cooperating therewith to hold said sheet to said one of said transport means.
  • An apparatus as in claim 1 including a plurality of said seals.
  • said first transport means comprises a pair of pinch rolls and wherein said second transport means comprises a vacuum transport having said suction means and wherein said first transport is located downstream of said fuser and wherein said second transport is located upstream of said fuser.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fixing For Electrophotography (AREA)
  • Separation, Sorting, Adjustment, Or Bending Of Sheets To Be Conveyed (AREA)
US00421710A 1973-12-04 1973-12-04 Fusing apparatus Expired - Lifetime US3849905A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US00421710A US3849905A (en) 1973-12-04 1973-12-04 Fusing apparatus
CA211,160A CA1045671A (fr) 1973-12-04 1974-10-10 Appareil de fusion
JP49136611A JPS5757704B2 (fr) 1973-12-04 1974-11-27

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US00421710A US3849905A (en) 1973-12-04 1973-12-04 Fusing apparatus

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JP (1) JPS5757704B2 (fr)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914097A (en) * 1974-02-01 1975-10-21 Eastman Kodak Co Sheet guide and cooling apparatus
US3987757A (en) * 1974-11-18 1976-10-26 Xerox Corporation Paper handling improvements in radiant fuser via corrugation of paper
US20150029280A1 (en) * 2013-07-29 2015-01-29 Seiko Epson Corporation Recording apparatus

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040702A (en) * 1958-06-19 1962-06-26 Nat Res Corp Vacuum coating apparatus having sealing means formed of membranes and fibers
US3071866A (en) * 1959-09-14 1963-01-08 Miami Herald Publishing Compan High speed photographic print drying machine
US3090134A (en) * 1960-06-01 1963-05-21 Liquefreeze Company Inc Gas locks
US3207129A (en) * 1962-04-17 1965-09-21 Limberger Walter Copying device
US3291468A (en) * 1965-05-05 1966-12-13 Electric Furnace Co Furnace seal means
US3505497A (en) * 1966-04-28 1970-04-07 Arlside Ltd Reprographic apparatus heater unit control

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040702A (en) * 1958-06-19 1962-06-26 Nat Res Corp Vacuum coating apparatus having sealing means formed of membranes and fibers
US3071866A (en) * 1959-09-14 1963-01-08 Miami Herald Publishing Compan High speed photographic print drying machine
US3090134A (en) * 1960-06-01 1963-05-21 Liquefreeze Company Inc Gas locks
US3207129A (en) * 1962-04-17 1965-09-21 Limberger Walter Copying device
US3291468A (en) * 1965-05-05 1966-12-13 Electric Furnace Co Furnace seal means
US3505497A (en) * 1966-04-28 1970-04-07 Arlside Ltd Reprographic apparatus heater unit control

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914097A (en) * 1974-02-01 1975-10-21 Eastman Kodak Co Sheet guide and cooling apparatus
US3987757A (en) * 1974-11-18 1976-10-26 Xerox Corporation Paper handling improvements in radiant fuser via corrugation of paper
US20150029280A1 (en) * 2013-07-29 2015-01-29 Seiko Epson Corporation Recording apparatus
US9446605B2 (en) * 2013-07-29 2016-09-20 Seiko Epson Corporation Recording apparatus

Also Published As

Publication number Publication date
CA1045671A (fr) 1979-01-02
JPS5091330A (fr) 1975-07-22
JPS5757704B2 (fr) 1982-12-06

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